Loss Of Mechanical Strength Research Articles

The microstructure and strength of a tantalum alloy: Influence of temperature

Tantalum-tungsten alloys are considered as potential materials used in high temperature applications due to their exceptional mechanical properties. To evaluate the mechanical properties of tantalum-tungsten alloys at elevated temperatures, a binary tantalum alloy containing 4 wt% tungsten (Ta–4%W) was chosen and their mechanical properties were tested at 1400–2000 °C, respectively, with the aid of a homemade coupled thermal-mechanical material testing system. The results show that the ultimate tensile stress, the yield stress and the uniform elongation gradually decrease, while the total tensile elongation keeps constant as the test temperature increases. Ta–4%W alloy have continuous work hardening capability at ultrahigh temperature even up to 2000 °C. The microstructural observations show that grain size increase and dislocation density decrease rapidly when the test temperature was increased to 1800 °C and 2000 °C. Furthermore, the dislocation substructure and dislocation types at elevated temperatures were analyzed and found to be distinctly different from that at room temperature. Base on the model between quantitative microstructural parameters and strength, the flow stress was calculated utilizing additive law from the microstructures with the structural morphology and related quantitative parameters. Mechanical strength loss of Ta–4%W at elevated temperature was evaluated after comparing the calculated and experimentally measured values.

Mechanical characterization and corrosive impacts of natural fiber reinforced composites: An experimental and numerical approach

The long-term durability and environmental degradation of the mechanical properties of natural fiber composites are very important in corrosive or humid environments. Therefore, the change in mechanical properties between the normal and corrosive environments was the key parameter for this study. The natural reinforcements were mainly unidirectional jute and banana fiber here. Glass fiber mats and aluminum foil were also used in one case each. Various types of composites were fabricated using different combinations. Multiple studies have examined the mechanical properties. Among those, the tensile and flexural strengths were examined both pre-post immersion in seawater for sixty days until saturation. The matrix began to erode, and micro cracks formed, resulting in a loss of mechanical strength. In addition, a water absorption characteristics curve with a coefficient of diffusion was determined. The tensile and flexural results were verified by finite element analysis. SEM micrographs enabled the identification of the weakening of the fiber/matrix interface induced by water ageing.

Strength and ductility loss of Magnesium-Gadolinium due to corrosion in physiological environment: Experiments and modeling

We propose a computational framework to study the effect of corrosion on the mechanical strength of magnesium (Mg) samples. Our work is motivated by the need to predict the residual strength of biomedical Mg implants after a given period of degradation in a physiological environment. To model corrosion, a mass-diffusion type model is used that accounts for localised corrosion using Weibull statistics. The overall mass loss is prescribed (e.g., based on experimental data). The mechanical behaviour of the Mg samples is modeled by a state-of-the-art Cazacu–Plunkett–Barlat plasticity model with a coupled damage model. This allowed us to study how Mg degradation in immersed samples reduces the mechanical strength over time. We performed a large number of in vitro corrosion experiments and mechanical tests to validate our computational framework. Our framework could predict both the experimentally observed loss of mechanical strength and the ductility due to corrosion for both tension and compression tests.

Non-destructive evaluation of GTAWA, GTAWF and LBWA welded Ti6Al4V alloy

Ti6Al4V is the most commonly used titanium alloy which features high strength with low density, high fracture toughness, excellent resistance against corrosion and good weldability. Ti6Al4V finds wide application in variety of sectors such as aircraft structure, jet engines, gas turbines, defence armour and IC engine components. The quality of the titanium weldments is significant in producing titanium structures and components. This requires critical Non-Destructive Testing (NDT) procedures to be followed. There is very scarce literature reported on NDT of titanium weldments. In this investigation the Non-Destructive Testing of Ti6Al4V weldments welded using Gas Tungsten Arc Welding – Autogenous (GTAWA), Gas Tungsten Arc Welding – with filler (GTAWF) and Laser Beam Welding – Autogenous (LBWA). The weldments were subjected NDT procedures such as visual and X-ray radiography. The uniqueness of this study is that the Image Quality Indicator (IQI) of aluminium was used as the IQI for titanium is not available in the industries. Generally, the titanium gets contaminated by gases in the atmosphere, leading to loss of mechanical strength and corrosion resistance of the weldment. Hence in this investigation a novel approach for ruling out the contamination of the weld pool and the Heat Affected Zone (HAZ) has been proposed viz. Weld Quality Indicator (WQI), i.e. the discolouration on the surface of the weldment is taken as an indicator of the contamination.

Influence of glass wool fiber reinforcement and heat resistant coating on behavior of self-compacting mortar at elevated temperatures

In present study, the influence of glass wool fiber (GWF) reinforcements and the application of heat resistant paint has been studied on the performance of self-compacting mortar (SCM) at ambient condition and at elevated temperatures of 200 °C, 400 °C, 600 °C, and 800 °C. Sixteen mix designs were prepared for SCM (with 25% fly ash) using GWF reinforcement of 0%, 0.5%, 1%, 1.5%, and varying the effective water to cement (w/c) ratio as; 0.43, 0.49, 0.55, and 0.70. The intrusion of GWF resulted into decrease in slump flow and v-funnel flow speed, increase in yield stress and plastic viscosity, whereas, the influence of effective w/c ratio on rheology of fresh SCM mix was opposite to glass wool fiber (GWF). For all variation of effective w/c ratio and GWF reinforcements, the values of slump flow and v-funnel flow were within the EFNARC limits. Increasing GWF reinforcement and the effective w/c ratio, compressive strength of SCM were decreased, but GWF yielded positive impact on flexural strength. SCM with 1% GWF reinforcements showed best result at effective w/c of 0.43, imparting highest flexural strength of 8.7 MPa. The application of heat resistant coating has shown a significant protection to SCM samples up to the maximum heating temperature of 800 °C by limiting the loss of mechanical strength within small percentage, whereas, the loss of mechanical strength was severe (about 45% to 65%) for uncoated samples. Thermogravimetric (TG) analysis of SCM powder revealed the thermal stability of SCM mix up to 1000 °C and the mass loss occurred correspond to the heating at temperature of 400 °C and 800 °C was 0.3%, and 7.5%, respectively.

Modeling and Optimization of Date Palm Fiber Reinforced Concrete Modified with Powdered Activated Carbon under Elevated Temperature

Date palm fiber (DPF) is one of the abundant solid waste materials in the agriculture sector in Saudi Arabia, and it is gaining great attraction due to its advantages compared to synthetic and other natural fibers. For proper utilization of DPF in cementitious composites, its performance under high temperatures needs to be understood. This is because DPF is a cellulose-based agricultural fiber material and is expected to degrade when subjected to high temperatures. This will cause a significant loss in strength and structural integrity of the composites. The use of Pozzolanic materials has been reported to reduce the loss in mechanical properties of cementitious composites under high temperatures. With powdered activated carbon (PAC) being a low-cost material compared to other Pozzolanic materials, this study utilized PAC as an additive to the DPF-reinforced concrete to mitigate its loss in mechanical strength when exposed to elevated temperature. The experiment was designed using response surface methodology (RSM), which was used to construct mathematical models for estimating the strengths of the concrete exposed to high temperatures. The DPF was added at proportions of 1%, 2%, and 3% by weight of cement. Similarly, the PAC was added at 1%, 2%, and 3% by weight of cement to the concrete. The concrete was subjected to elevated temperatures of 300 °C, 600 °C, and 900 °C for a 2 h exposure period. The degradation of the concrete in terms of mass loss and the compressive strength of the concrete after heating were measured. DPF in the concrete led to an escalation in weight loss and reduction in strength, which was more pronounced at a temperature of 600 °C and above. The addition of PAC resulted in an enhancement in the strengths of the concrete containing up to 2% DPF at 300 °C, while at 600 °C the improvement was minimal. The models developed for predicting the mass loss and strengths of the DPF-reinforced concrete under high temperatures were statistically significant with a high correlation degree. Based on the optimization results, DPF-reinforced concrete produced with 1% DPF, and 2.27% PAC as additives and subjected to a temperature of 300 °C for 2 h yielded the lowest mass loss of 2.05%, highest residual compressive strength and relative strength of 45.85 MPa and 106.7% respectively.

Regulation of Wnt Signaling Pathway by Costic Acid Derivative, An Efficient Strategy for Treatment of Glucocorticoid‐Induced Osteoporosis in Rat Model

AbstractOsteoporosis leads to a decrease in bone mass, loss of mechanical strength, increase in fracture susceptibility and is a serious medical problem worldwide. The present study investigated the effect of costic acid derivative (CA) on dexamethasone (DXM)‐induced osteoporosis in vitro in osteoblasts and in vivo in rat a model. The results demonstrated that DXM‐mediated reduction in osteoblast viability was effectively prevented by CA treatment in dose‐dependent manner. The DXM‐induced loss of osteoblast viability was completely reversed by CA treatment at 4 μM dose. Treatment of the primary osteoblasts with 0. 5 and 4 μM CD for 72 h reversed DXM‐mediated reduction in ALP activity. The CA treatment significantly (P>0.05) reversed DXM‐mediated lowering of osteoclacin, collagen type‐1 and osteonectin mRNA expression. The CA treatment at 1.5, 3 and 6 mg/kg doses significantly (P>0.05) reversed DXM‐mediated decrease in BMD in rat femurs. Treatment of the rats with CA reversed DXM‐mediated changes in osteocalcin and CTX levels in serum samples. Administration of CA to the rats reversed DXM‐mediated decrease in Wnt, β‐catenin expression and increase in SOST and Dickkopf‐1 level. Docking studies showed that CA interacts with mammalian Wnt‐frizzled complex (6AHY) through conventional H‐bonding. Thus, CA inhibits DXM‐induced dysfunction of osteoblast differentiation in vitro and inhibits osteoporosis development in vivo in rat model. Therefore, CA may be developed as a potential therapeutic agent for treatment of bone damage induced by glucocorticoid (GC)‐mediated osteoporosis.

Kinin B2 and B1 Receptors Activation Sensitize the TRPA1 Channel Contributing to Anastrozole-Induced Pain Symptoms.

Aromatase inhibitors (AIs) cause symptoms of musculoskeletal pain, and some mechanisms have been proposed to explain them. However, signaling pathways downstream from kinin B2 (B2R) and B1 (B1R) receptor activation and their possible sensitizing of the Transient Receptor Potential Ankyrin 1 (TRPA1) remain unknown. The interaction between the kinin receptor and the TRPA1 channel in male C57BL/6 mice treated with anastrozole (an AI) was evaluated. PLC/PKC and PKA inhibitors were used to evaluate the signaling pathways downstream from B2R and B1R activation and their effect on TRPA1 sensitization. Anastrozole caused mechanical allodynia and muscle strength loss in mice. B2R (Bradykinin), B1R (DABk), or TRPA1 (AITC) agonists induced overt nociceptive behavior and enhanced and prolonged the painful parameters in anastrozole-treated mice. All painful symptoms were reduced by B2R (Icatibant), B1R (DALBk), or TRPA1 (A967079) antagonists. We observed the interaction between B2R, B1R, and the TRPA1 channel in anastrozole-induced musculoskeletal pain, which was dependent on the activation of the PLC/PKC and PKA signaling pathways. TRPA1 seems to be sensitized by mechanisms dependent on the activation of PLC/PKC, and PKA due to kinin receptors stimulation in anastrozole-treated animals. Thus, regulating this signaling pathway could contribute to alleviating AIs-related pain symptoms, patients' adherence to therapy, and disease control.

Composite alkali-activated materials with waste tire rubber designed for additive manufacturing: an eco-sustainable and energy saving approach

There is an increasing trend in research projects and case studies to demonstrate the potential of Additive Manufacturing (AM) with concrete, better known as 3D concrete printing. Like ordinary construction, the latest upgrades on this topic are strongly focused towards improving eco-sustainability in terms of low-carbon materials. Low-carbon binders’ alternative to Portland cement and the utilisation of selected waste materials in place to virgin aggregates has high potential in fulfilling the sustainable development goals. In this paper, an experimental study was performed by incorporating ground waste tire rubber aggregates of different size gradation (0–1 mm and 1–3 mm) and replacement levels (50 v/v% and 100 v/v%) in a “greener” alkali-activated mix designed for 3D printing applications. First, the experimental program involved the optimization of mix design rheology and printing parameters to successfully integrate rubber aggregates into the printable alkali-activated mixtures. Then, a comprehensive characterization, including static mechanical testing, dynamic thermo-mechanical analysis, thermal conductivity testing, and acoustic insulation measurements was conducted. Comparison with identical Portland-based rubberized formulations designed for AM revealed better mechanical isotropy, flexural strength, thermo-mechanical behaviour, heat insulation, and high-frequency acoustic insulation for alkali-activated composites. The influence of rubber aggregate size on the fresh and hardened state behaviour of the mixes was also studied and discussed. Keeping the losses in mechanical strength restrained, the rubberized composites designed in this study have demonstrated significant thermal and acoustic insulation properties that are desired for energy-saving applications in buildings. The research verified the practicability of using waste aggregates in low-carbon binders for sustainable lightweight and thermo-acoustically effective applications, establishing an attractive starting point to address future research on material optimization for practical purposes.

Incorporating Tantalum Oxide Nanoparticles into Implantable Polymeric Biomedical Devices for Radiological Monitoring.

Longitudinal radiological monitoring of biomedical devices is increasingly important, driven by the risk of device failure following implantation. Polymeric devices are poorly visualized with clinical imaging, hampering efforts to use diagnostic imaging to predict failure and enable intervention. Introducing nanoparticle contrast agents into polymers is a potential method for creating radiopaque materials that can be monitored via computed tomography. However, the properties of composites may be altered with nanoparticle addition, jeopardizing device functionality. Thus, the material and biomechanical responses of model nanoparticle-doped biomedical devices (phantoms), created from 0-40 wt% tantalum oxide (TaOx ) nanoparticles in polycaprolactone and poly(lactide-co-glycolide) 85:15 and 50:50, representing non, slow, and fast degrading systems, respectively, are investigated. Phantoms degrade over 20 weeks in vitro in simulated physiological environments: healthy tissue (pH 7.4), inflammation (pH 6.5), and lysosomal conditions (pH 5.5), while radiopacity, structural stability, mechanical strength, and mass loss are monitored. The polymer matrix determines overall degradation kinetics, which increases with lower pH and higher TaOx content. Importantly, all radiopaque phantoms could be monitored for a full 20 weeks. Phantoms implanted in vivo and serially imaged demonstrate similar results. An optimal range of 5-20 wt% TaOx nanoparticles balances radiopacity requirements with implant properties, facilitating next-generation biomedical devices.

The Influence of Assembly Unit of Fibers on the Mechanical and Long-Term Properties of Reactive Powder Concrete

The corrosion of concrete structures by chloride salt is very significant in coastal environments. In order to improve the durability of marine concrete structures, cement-based materials with high durability need to be developed. In this investigation, the influence of NaCl freeze–thaw cycles (FT-C) and NaCl dry-wet alternations (DW-A) on the flexural and compressive strengths of reactive powder concrete (RPC) with an assembly unit of basalt fibers and steel fibers is studied. Additionally, the mass loss rate, the relative dynamic modulus of elasticity (RDEM), the chloride ion migration coefficient (CMC) and the impact toughness are measured after the NaCl FT-C and DW-A action. Our findings show that the RDEM, mass loss, and mechanical strength loss of RPC are increased by the ascending NaCl FT-C and DW-A. Meanwhile, the RDEM and the impact toughness are decreased by the NaCl FT-C and DW-A. The RPC with 0.5% basalt fibers and 1.5% steel fibers by volume of RPC shows the optimum mechanical performance and resistance to NaCl FT-C and DW-A. However, RPC with 3% steel fibers shows the worst resistance to NaCl erosion. The maximum mass loss rates, RDEM, flexural strength loss rate, compressive strength loss rate, CMC and impact toughness of all specimens after 300 NaCl FT-C and 30 NaCl DW-A are 4.5%, 91.7%, 28.1%, 29.3%, 3.2 × 10−12 (m2/s) and 2471 J. Meanwhile, the corresponding minimum values are 1.62%, 83.2%, 20.4%, 15.7%, 1.1 × 10−12 (m2/s) and 625 J. The researching findings will provide an optimum mix ratio of RPC with an assembly unit of basalt fibers and steel fibers, which can be applied in the marine engineering environment.

Sugarcane Bagasse as Aggregate in Composites for Building Blocks

Each year, hundreds of millions of tons of processed sugarcane generate, by weight, 25 to 30% of bagasse as waste, whose destination is combustion for energy cogeneration. This research proposes an alternative and more sustainable use for this waste. The use of sugarcane bagasse (SCB) as the single aggregate in composites for building blocks was studied. The raw bagasse was used without any treatment. As the binder, aerial lime and/or soil were used. Both provided enough mechanical strength for non-load-bearing walls. The composite of SCB with soil achieved the best performance in terms of mechanical resistance: 2.6 MPa in compressive strength and 2.1 MPa in bending strength, while the composite of SCB with lime achieved 1.76 MPa and 1.7 MPa, respectively. The higher number of fibers in the SCB/lime mixture provides better thermal insulation than clay brick or conventional concrete, such as “hempcrete”. The lime composites obtained greater water resistance and less loss of mechanical strength when saturated. However, the higher water absorption coefficient makes it necessary to apply a waterproof mortar on surfaces exposed to the weather. The replacement of supplied blocks by SCB blocks can offer a better and more economical solution that improves the quality of the built environment and is more ecofriendly.

Preliminary Studies on Conversion of Sugarcane Bagasse into Sustainable Fibers for Apparel Textiles

Owing to increased environmental awareness and the implementation of stringent governmental regulations, the demand for the valorization of natural fibers has increased in recent years. Sugarcane bagasse after juice extraction could be a potential source of natural fibers to be used in textile applications. In this paper, sugarcane bagasse is converted to textile fibers. Sugarcane fibers are extracted through alkali and H2O2 treatment with varying concentrations (6, 10, 14) g/L and (8, 12, 16) g/L, respectively. To soften the fibers for textile use, extracted fibers were post-treated with a constant ratio of silicone softener (50 g/L). Treatment of sugarcane fibers with varying concentrations of alkali–H2O2 significantly influenced the fiber surface morphology. Furthermore, an increase in the crystallinity of extracted fibers was observed, whereas a reduction in fiber linear density from 54.82 tex to 45.13 tex as well as moisture regain (6.1% to 5.1%) was observed as the ratio of alkali–H2O2 treatment was increased. A notable improvement in overall mechanical strength was achieved upon alkali–H2O2 treatment, but at a higher concentration (conc.) there was a loss of mechanical strength, and the torsional and flexural rigidity also increased significantly. Based on the results, sugarcane fibers treated with 10 g/L NaOH, 12 g/L H2O2 and 50 g/L silicone softener showed the most optimum results. These sustainable fibers have the potential to be used in textile applications due to their enhanced softness, optimum moisture regain, and better mechanical properties.

Engineering behavior of cement-treated stiff clay subjected to freezing/thawing cycles

Deep soil mixing (DSM) with cement has been adopted to enhance soft ground and stabilize problematic soils worldwide. The literature is limited to DSM-treated soft soils with low cement contents, temperate curing conditions, short-term stability, and compressive properties. Due to the increased applications of DSM in cold regions, the study on the mechanical behavior of cemented soils (soilcrete) with high cement content under freezing/thawing (F/T) conditions has become important. In the present study, cylindrical specimens formed by mixing Edmonton stiff clay with high ordinary Portland cement contents (over 20%) were prepared in the lab to examine the mechanical behavior of soilcrete under unexposed and F/T exposed conditions. Unconfined compression and tensile tests were performed to assess changes in the mechanical properties of specimens cured for 1 to 300 days after 1 to 20 F/T cycles at freezing temperatures from −2 to −20 °C. Test results showed that the compressive and tensile strength of soilcrete increased with curing age and decreased significantly with more F/T cycles. Additionally, the mechanical strength loss in the −5 to −10 °C range was more significant than in the −2 to −5 °C range, indicating that the lower temperature caused more severe damage to the samples. Although the mass loss was <5% for most samples, it increased with more F/T cycles and the declining temperature, indicating that the mass loss was able to reflect the impact of F/T cycles.

Recycling of Concrete Demolition Waste Powder as a Sustainable Material in Portland Cement Pastes Modified with Nano-silica

In recent years, researchers dedicated themselves to explore the possibility of introducingconcrete waste powder (CWP) into Portland cement as a sustainable material for Portland cement to reduce as possible the environmental pollution with this concrete demolition wastes. To optimize the effect of CWP on cement-based materials, this paper usesnano-silica (NS) to improve the hydration and mechanical properties of cement-based materials with CWP. Results indicated that after adding NS into CWP cement pastes, the setting time of cement pastes was significantly reduced, while the early rate of hydration and hydration heat increased. Besides, the mechanical strengths of the cement pastes increased as CWP replaced at the expense of the cement only up till 15 weights %, and then decreased. The addition of nanosilica (NS) can compensate the mechanical strength loss caused by CWP as supplementary cementing materials. The higher ratios of CWP than 15 weight % increased the pore volume or porosity. In contrast, NS in CWP blended cement significantly decreased the porosity, and increased the proportion of harmless pores. Hence, NS reduced the porosity, which in turn improved and enhanced the bulk density and mechanical properties. The optimum amount of NS is 2.5 weight % which resulted in the best results. The heat of hydration of the different cement batches in the two groups adversely affected with the incorporation of CWP, but little improved with NS. The obtained results were confirmed by the ultrasonic pulse velocity (USPV) test, where the cement batch PP15 (Group I) and PS2.5 (Group II) achieved the highest conformance.

Quantitative evaluation of deep-shallow compound defects using frequency-band-selecting pulsed eddy current testing

Deep-shallow compound defects (DSCD) may occur in both single-layer and multi-layer structures and commit great loss of structural mechanical strength. Their quantification, especially in depth, is hence imperatively required for guaranteeing the integrity and safety of engineering structures. In this paper, the defect parameters of DSCD are identified by frequency-band-selecting pulsed eddy current testing (FSPECT), and a strategy of component separation is proposed. The high-frequency component is separated from the FSPECT responses for the quantification of shallow defects so that the parameters of deep defects in DSCD can be reconstructed, which is the ultimate objective of FSPECT method. Finite element analysis (FEA) was conducted on the single-layer structure to preview the feasibility of the proposed method and to highlight the signal feature of better sensitivity. Subsequently, validation experiments were implemented on the double-layer structure and identified the features suitable for the shallow and deep defects. Besides, error propagation of the proposed method was also discussed. Results from FEA simulations and experiments show that (a) the strategy of component separation enables the quantitative evaluation of DSCD, (b) peak value (PV) should be chosen for the quantification of shallow defects while for the identification of deep defects time to zero-cross (TZC) is suggested, and (c) the deep defect can still be characterized despite the little error in the estimation of shallow defects.

Mechanical and thermophysical properties of cement mortars including bio-based microencapsulated phase change materials

This study investigates the mechanical and thermophysical performance of cement mortars incorporating microencapsulated phase change materials (mPCMs), which consist of an aqueous dispersion of 100% bio-based fine core–shell particles. A specific protocol was used to manufacture the mortar samples, which ensures a homogeneous particle distribution and prevents microcapsule leakage. The addition of mPCMs to the mortar causes both a decrease in density, an increase in porosity, and a substantial loss of mechanical strength. Conversely, hot-disk characterization revealed a large improvement in the thermal performance. The system containing 8 wt% mPCMs exhibits a good balance between its mechanical and thermal properties.

Poly(arylene ether nitrile)/lamellar MXene nanosheet composite films fabricated via bio-inspired dopamine surface chemistry

2D lamellar MXene nanosheets have shown the promising candidate for preparing dielectric polymer composites due to their excellent electrical and mechanical properties. However, the high dielectric loss and low temperature resistance restrict their further application, which are still big challenges. In this work, MXene nanosheets were modified by dopamine mediated chemical crosslinking with polyethylenimine, which was further incorporated into the temperature-resistant poly (arylene ether nitrile) (PEN) matrix via a simple solution-casting method to prepare the dielectric MXene/PEN composite film. Specially, the insulating layer originated from polyethylenimine and polydopamine not only enhanced the interface polarization and the uniform dispersion of MXene in the polymer matrix, but also prevented the formation of conductive network. As a result, the MXene/PEN composite film achieved the high dielectric constant of 13.3 (1 kHz) when filling content was 7 wt%, and the dielectric loss was suppressed to 0.042. As the filling content reached 5 wt%, the MXene/PEN composite film had the maximum tensile strength and tensile modulus of 70.9 MPa and 3042.6 MPa, respectively, while maintaining a high elongation at break larger than 6.5%. In addition, the composite film retained the thermal decomposition temperature (T10%) of 460–521°C and the glass transition temperature higher than 149°C. Therefore, this work provides an alternative way to prepare thermally stable and dielectric polymer composite film with high mechanical strength and low dielectric loss, which is essential to the modern electronic applications.

Fabrication and Evaluation of Electrospun Silk Fibroin/Halloysite Nanotube Biomaterials for Soft Tissue Regeneration.

The production of nanofibrous materials for soft tissue repair that resemble extracellular matrices (ECMs) is challenging. Electrospinning uniquely produces scaffolds resembling the ultrastructure of natural ECMs. Herein, electrospinning was used to fabricate Bombyx mori silk fibroin (SF) and SF/halloysite nanotube (HNT) composite scaffolds. Different HNT loadings were examined, but 1 wt% HNTs enhanced scaffold hydrophilicity and water uptake capacity without loss of mechanical strength. The inclusion of 1 wt% HNTs in SF scaffolds also increased the scaffold’s thermal stability without altering the molecular structure of the SF, as revealed by thermogravimetric analyses and Fourier transform infrared spectroscopy (FTIR), respectively. SF/HNT 1 wt% composite scaffolds better supported the viability and spreading of 3T3 fibroblasts and the differentiation of C2C12 myoblasts into aligned myotubes. These scaffolds coated with decellularised ECM from 3T3 cells or primary human dermal fibroblasts (HDFs) supported the growth of primary human keratinocytes. However, SF/HNT 1 wt% composite scaffolds with HDF-derived ECM provided the best microenvironment, as on these, keratinocytes formed intact monolayers with an undifferentiated, basal cell phenotype. Our data indicate the merits of SF/HNT 1 wt% composite scaffolds for applications in soft tissue repair and the expansion of primary human keratinocytes for skin regeneration.

Exercise-Linked Skeletal Irisin Ameliorates Diabetes-Associated Osteoporosis by Inhibiting the Oxidative Damage-Dependent miR-150-FNDC5/Pyroptosis Axis.

Recent evidence suggests that physical exercise (EX) promotes skeletal development. However, the impact of EX on the progression of bone loss and deterioration of mechanical strength in mice with type 2 diabetic mellitus (T2DM) remains unexplored. In the current study, we investigated the effect of EX on bone mass and mechanical quality using a diabetic mouse model. The T2DM mouse model was established with a high-fat diet with two streptozotocin injections (50 mg/kg/body wt) in C57BL/6 female mice. The diabetic mice underwent treadmill exercises (5 days/week at 7-11 m/min for 60 min/day) for 8 weeks. The data showed that diabetes upregulated miR-150 expression through oxidative stress and suppressed FNDC5/Irisin by binding to its 3'-untranslated region. The decreased level of irisin further triggers the pyroptosis response in diabetic bone tissue. EX or N-acetyl cysteine or anti-miRNA-150 transfection in T2DM mice restored FNDC5/Irisin expression and bone formation. Furthermore, EX or recombinant irisin administration prevented T2DM-Induced hyperglycemia and improved glucose intolerance in diabetic mice. Furthermore, osteoblastic knockdown of Nlrp3 silencing (si-Nlrp3) or pyroptosis inhibitor (Ac-YVADCMK [AYC]) treatment restores bone mineralization in diabetic mice. Micro-computed tomography scans and mechanical testing revealed that trabecular bone microarchitecture and bone mechanical properties were improved after EX in diabetic mice. Irisin, either induced by skeleton or daily EX or directly administered, prevents bone loss by mitigating inflammasome-associated pyroptosis signaling in diabetic mice. This study demonstrates that EX-induced skeletal irisin ameliorates diabetes-associated glucose intolerance and bone loss and possibly provides a mechanism of its effects on metabolic osteoporosis.