Fluid dynamics and thermodynamics numerical modelling of self-healing fibre reinforced laminated composites

Inspired by the bleeding mechanism in living organisms to heal injury for survival, such capability has been integrated into a damaged laminate composite for autonomous internal repairing to extend its service life. The main healing mechanisms include infiltration of healing liquid into the crack plane, resulted from the breaching of pre-embedded vessels, which is triggered by a damage event. The later polymerization of the healant serves to restore the strength of the crack plane and hence inhibits further crack growth. The best healing performance is generally governed by both infiltration and polymerization rates of healing liquid at the crack tip. In ensuring assessment of these rates without excessive computational burden but free from the companion numerical stability-consistency-accuracy issues, in-house hydrodynamic and thermodynamic models based on the weak form Galerkin finite element (FE) method have been developed in this study. To simulate the micro-scale isothermal hydrodynamics of the Newtonian liquid, one-dimensional (1D) incompressible Stokes equations have been solved using the penalty function method. Computational matters, such as the feasible penalty parameter (γp) for multiple flow geometries of single straight micro-channel, are discussed and numerically addressed. Meanwhile, the polymerization mechanics of healing liquid in a straight crack channel is obtained by solving the heat conduction formulation coupled with the phenomenological Arrhenius’s rate equation and Crank-Nicolson time scheme. It is observed that the iterative Uzawa’s technique, which employs forcing term correction in terms of the previous velocity solution, coupled with another forcing term correction in terms of the previous divergence of velocity solution is capable of eliminating the instability of axial pressure distribution and inconsistency of the conventional penalty model setting. Additionally, implementing termination criterion by equalizing the order of both maximum elemental divergence of velocity (EDVmax) and penalty parameter ensures stability, consistency, and accuracy of solution for 1 x 101 ≤ γp ≤ 1 x 1011. Adopting similar termination technique for the Crank-Nicolson predictor-corrector time integration scheme with the penalty formulation, the proposed model is capable of capturing the flow front motion in micro-channel by electing the temporal mesh size (Δt) from a function of hydraulic diameter (Dh) and spatial mesh size (Δx). Parametric study for temperature and cure degree evolution by varying pre-exponential factor ( ˜ A), activation energy (˜E ), ˜n-th order of reaction, and ultimate enthalpy of cure ( ˜H ) has been performed thoroughly where an optimal coupling between ˜ A and ˜E is identified as the dominating factor in achieving the most favored repairing behavior. While the order of reaction imparts less significance in the evaluation, it is observed that polymeric healant with a higher numerical value of ˜H is not beneficial either. The principal contribution of the present study includes the construction of a series of FE Eulerian frameworks that are reliable, without excessive computational burden, in assessing key diffusive mechanistic variables of extrinsic self-healing mechanisms in achieving optimal strength recovery of straight crack geometry in polymeric materials

Towards sustainable polymeric materials: zero waste, green and self-healing

Although polymeric materials are widely adopted in various applications, the sustainability of the materials is often controversial, particularly on the current handling of polymeric wastes and the use of non-renewable resources as raw materials. A brief review is hence given to outline recent efforts that promote sustainable value of the materials. The discussion starts with the recycling activities of polymeric wastes. Next, the concept of ecofriendly composites, which include bio-based and biodegradable, is discussed. Then, a note on inclusion of self-healing functionality in polymeric composite that is seen as another promising methodology in meriting the sustainability of polymeric materials is offered. Furthermore, the feasibility and possible improvement of the aforementioned methodologies (i.e. zero waste and green concept) are highlighted and discussed. In conclusion, more research works on the individual or combination of the improved methodologies and a concise evaluator are needed to extend further the sustainable potential of polymeric materials

Bending response of cross-ply laminated composite plates with diagonally perturbed localized interfacial degeneration

A laminated composite plate element with an interface description is developed using the finite element approach to investigate the bending performance of two-layer cross-ply laminated composite plates in presence of a diagonally perturbed localized interfacial degeneration between laminae. The stiffness of the laminate is expressed through the assembly of the stiffnesses of lamina sub-elements and interface element, the latter of which is formulated adopting the well-defined virtually zero-thickness concept. To account for the extent of both shear and axial weak bonding, a degeneration ratio is introduced in the interface formulation. The model has the advantage of simulating a localized weak bonding at arbitrary locations, with various degeneration areas and intensities, under the influence of numerous boundary conditions since the interfacial description is expressed discretely. Numerical results show that the bending behavior of laminate is significantly affected by the aforementioned parameters, the greatest effect of which is experienced by those with a localized total interface degeneration, representing the case of local delaminatio

Antiinflammatory Therapy with Canakinumab for Atherosclerotic Disease

Background: Experimental and clinical data suggest that reducing inflammation without affecting lipid levels may reduce the risk of cardiovascular disease. Yet, the inflammatory hypothesis of atherothrombosis has remained unproved. Methods: We conducted a randomized, double-blind trial of canakinumab, a therapeutic monoclonal antibody targeting interleukin-1β, involving 10,061 patients with previous myocardial infarction and a high-sensitivity C-reactive protein level of 2 mg or more per liter. The trial compared three doses of canakinumab (50 mg, 150 mg, and 300 mg, administered subcutaneously every 3 months) with placebo. The primary efficacy end point was nonfatal myocardial infarction, nonfatal stroke, or cardiovascular death. RESULTS: At 48 months, the median reduction from baseline in the high-sensitivity C-reactive protein level was 26 percentage points greater in the group that received the 50-mg dose of canakinumab, 37 percentage points greater in the 150-mg group, and 41 percentage points greater in the 300-mg group than in the placebo group. Canakinumab did not reduce lipid levels from baseline. At a median follow-up of 3.7 years, the incidence rate for the primary end point was 4.50 events per 100 person-years in the placebo group, 4.11 events per 100 person-years in the 50-mg group, 3.86 events per 100 person-years in the 150-mg group, and 3.90 events per 100 person-years in the 300-mg group. The hazard ratios as compared with placebo were as follows: in the 50-mg group, 0.93 (95% confidence interval [CI], 0.80 to 1.07; P = 0.30); in the 150-mg group, 0.85 (95% CI, 0.74 to 0.98; P = 0.021); and in the 300-mg group, 0.86 (95% CI, 0.75 to 0.99; P = 0.031). The 150-mg dose, but not the other doses, met the prespecified multiplicity-adjusted threshold for statistical significance for the primary end point and the secondary end point that additionally included hospitalization for unstable angina that led to urgent revascularization (hazard ratio vs. placebo, 0.83; 95% CI, 0.73 to 0.95; P = 0.005). Canakinumab was associated with a higher incidence of fatal infection than was placebo. There was no significant difference in all-cause mortality (hazard ratio for all canakinumab doses vs. placebo, 0.94; 95% CI, 0.83 to 1.06; P = 0.31). Conclusions: Antiinflammatory therapy targeting the interleukin-1β innate immunity pathway with canakinumab at a dose of 150 mg every 3 months led to a significantly lower rate of recurrent cardiovascular events than placebo, independent of lipid-level lowering. (Funded by Novartis; CANTOS ClinicalTrials.gov number, NCT01327846.

Flexural performance of laminated composite plates with diagonally perturbed localized delamination

This paper investigates flexural performance of laminated composite plates in the presence of imperfect bonding in terms of localized delamination, commonly observed in manufacturing process, using finite element method incorporating virtually zero thickness interface element. The structural response in terms of maximum deflection of two-layer, built-in, and square composite laminates under the influence of transverse load is considered. For the discretization, each finite element is formulated such that it is consisting of three sub-elements representing the top and bottom composite laminae as well as the interface in between. Perturbation of localized interface rigidity is carried out diagonally with imperfection ratio, R, for numerous fiber orientations and damage intensities indicated by delamination area. In addition, location effect is examined by placing these damages at various sites characterized by the distance ratio measured from the laminated composite plate's center. A polar plot describing relative rigidity change for various damage intensities and locations as well as fiber angles has been produced to generalize the findings. Normalized rigidity is, in general, demonstrated to have a direct correlation with distance ratio for plates with high damage intensities. For similar degree of damage intensity, increase in orientation mismatch of top and bottom layers reduces the rigidity ratio, relative to that of matching fiber angles, corresponding to an increase in distance ratio. Flexural behavior of laminates with small delamination area is insensitive to position of imperfection although a drop in rigidity is shown in comparison to that with perfect bonding

PRL3-zumab as an immunotherapy to inhibit tumors expressing PRL3 oncoprotein

Tumor-specific antibody drugs can serve as cancer therapy with minimal side effects. A humanized antibody, PRL3-zumab, specifically binds to an intracellular oncogenic phosphatase PRL3, which is frequently expressed in several cancers. Here we show that PRL3-zumab specifically inhibits PRL3+ cancer cells in vivo, but not in vitro. PRL3 antigens are detected on the cell surface and outer exosomal membranes, implying an ‘inside-out’ externalization of PRL3. PRL3-zumab binds to surface PRL3 in a manner consistent with that in classical antibody-dependent cell-mediated cytotoxicity or antibody-dependent cellular phagocytosis tumor elimination pathways, as PRL3-zumab requires an intact Fc region and host FcγII/III receptor engagement to recruit B cells, NK cells and macrophages to PRL3+ tumor microenvironments. PRL3 is overexpressed in 80.6% of 151 fresh-frozen tumor samples across 11 common cancers examined, but not in patient-matched normal tissues, thereby implicating PRL3 as a tumor-associated antigen. Targeting externalized PRL3 antigens with PRL3-zumab may represent a feasible approach for anti-tumor immunotherapy.ASTAR (Agency for Sci., Tech. and Research, S’pore)Published versio

PRL3-zumab as an immunotherapy to inhibit tumors expressing PRL3 oncoprotein (vol 10, 2484, 2019)

10.1038/s41467-021-26548-6NATURE COMMUNICATIONS12