An Overview of PRP-Delivering Scaffolds for Bone and Cartilage Tissue Engineering

Tissue engineering is nowadays an emerging approach that aims to replace or regenerate diseased or damaged organs with engineered constructs. Considering the key role of growth factors (GFs) in the tissue regeneration process, these biomolecules are considered an important part of the tissue engineering process, so the presence of growth factors in engineered scaffolds can accelerate tissue regeneration by influencing the behavior of cells. Platelet-rich plasma (PRP), as an autologous source of a variety of growth factors, is considered a therapeutic agent for the treatment of degenerative diseases. Regarding its ability to promote the healing process and tissue regeneration, PRP therapy has attracted great attention in bone and cartilage tissue engineering. Incorporating PRP and its derivatives into engineered scaffolds not only bioactivates the scaffold, but the scaffold matrix also acts as a sustained and localized growth factor release system. In addition, the presence of a scaffold can promote the bioactivity of GFs by providing an environment that facilitates their interaction, leading to enhanced effects compared to their free form. This review presents a brief overview of PRP's role in bone and cartilage tissue regeneration with the main focus on scaffold-mediated PRP delivery. In addition, the classification of platelet-rich products, current extraction techniques, terminology, and scaffold bioactivation methods are presented to provide a better understanding of the basics and the key aspects that may affect the effectiveness of therapy in bone and cartilage tissue engineering.

Renal Pathology Images Segmentation Based on Improved Cuckoo Search with Diffusion Mechanism and Adaptive Beta-Hill Climbing

Lupus Nephritis(LN)is a significant risk factor for morbidity and mortality in systemic lupus erythematosus,and nephropathology is still the gold standard for diagnosing LN.To assist pathologists in evaluating histopathological images of LN,a 2D Rényi entropy multi-threshold image segmentation method is proposed in this research to apply to LN images.This method is based on an improved Cuckoo Search(CS)algorithm that introduces a Diffusion Mechanism(DM)and an Adaptiveβ-Hill Climbing(AβHC)strategy called the DMCS algorithm.The DMCS algorithm is tested on 30 benchmark functions of the IEEE CEC2017 dataset.In addition,the DMCS-based multi-threshold image segmentation method is also used to segment renal pathological images.Experimental results show that adding these two strategies improves the DMCS algorithm's ability to find the optimal solution.According to the three image quality evaluation metrics:PSNR,FSIM,and SSIM,the proposed image segmentation method performs well in image segmentation experiments.Our research shows that the DMCS algorithm is a helpful image segmentation method for renal pathological images.

Jumbo Bionic Trabecular Metal Acetabular Cups Improve Cup Stability During Acetabular Bone Defect Reconstruction:A Finite Element Analysis Study

The biomechanical effects of acetabular revision with jumbo cups are unclear.This study aimed to compare the biomechanical effects of bionic trabecular metal vs.titanium jumbo cups for the revision of acetabular bone defects.We designed and reconstructed American Academy of Orthopaedic Surgeons(AAOS)type I–III acetabular bone defect models using computed tomography scans of a man without acetabular bone defects.The implantation of titanium and trabecular metal jumbo cups was simulated.Stress distribution and relative micromotion between the cup and host bone were assessed using finite element analysis.Contact stress on the screws fixing the cups was also analyzed.The contact stress analysis showed that the peak contact stress between the titanium jumbo cup and the host bone was 21.7,20.1,and 23.8 MPa in the AAOS I–III models,respectively;the corresponding values for bionic tantalum jumbo cups decreased to 4.7,6.7,and 11.1 MPa.Analysis of the relative micromotion showed that the peak relative micromotion between the host bone and the titanium metal cup was 10.2,9.1,and 11.5μm in the AAOS I–III models,respectively;the corresponding values for bionic trabecular metal cups were 17.2,18.2,and 31.3μm.The peak contact stress on the screws was similar for the 2 cup types,and was concentrated on the screw rods.Hence,acetabular reconstruction with jumbo cups is biomechanically feasible.We recommend trabecular metal cups due to their superior stress distribution and higher relative micromotion,which is within the threshold for adequate bone ingrowth.

Boosting Kernel Search Optimizer with Slime Mould Foraging Behavior for Combined Economic Emission Dispatch Problems

Reducing pollutant emissions from electricity production in the power system positively impacts the control of greenhouse gas emissions.Boosting kernel search optimizer(BKSO)is introduced in this research to solve the combined economic emission dispatch(CEED)problem.Inspired by the foraging behavior in the slime mould algorithm(SMA),the kernel matrix of the kernel search optimizer(KSO)is intensified.The proposed BKSO is superior to the standard KSO in terms of exploitation ability,robustness,and convergence rate.The CEC2013 test function is used to assess the improved KSO's performance and compared to 11 well-known optimization algorithms.BKSO performs better in statistical results and convergence curves.At the same time,BKSO achieves better fuel costs and fewer pollution emissions by testing with four real CEED cases,and the Pareto solution obtained is also better than other MAs.Based on the experimental results,BKSO has better performance than other comparable MAs and can provide more economical,robust,and cleaner solutions to CEED problems.

The Development of a Venus Flytrap Inspired Soft Robot Driven by IPMC

In recent years,more and more creatures in nature have become the source of inspiration for people to study bionic soft robots.Many such robots appear in the public’s vision.In this paper,a Venus flytrap robot similar to the biological Venus flytrap in appearance was designed and prepared.It was mainly cast by Polydimethylsiloxane(PDMs)and driven by the flexible material of Ionic Polymer Metal Composites(IPMCs).Combining with ANSYS and related experiments,the appropriate voltage and the size of IPMC were determined.The results showed that the performance of the Venus flytrap robot was the closest to the biological Venus flytrap when the size of IPMC length,width and driving voltage reach to 3 cm,1 cm and 5.5 V,respectively.Moreover,the closing speed and angle reached 8.22°/s and 37°,respectively.Finally,the fly traps also could be opened and closed repeatedly and captured a small ball with a mass of 0.3 g firmly in its middle and tip.

Shock-Resistant and Energy-Absorbing Properties of Bionic NiTi Lattice Structure Manufactured by SLM

Each specific structure of organisms is the best choice under specific circumstances.The excellent characteristic structures of these organisms have great application potential in the design and multi-functional optimization of energy-absorbing structures such as vehicle collisions,satellite landings,and military equipment.In this paper,using the principle of structural bionics,using the advantages of the honeycomb structure and the light weight and high strength of beetle elytra,four bionic lattice structures are studied:CH,ZPRH,SCH and IBE.Using NiTi shape memory alloy,a unique material as the base material,samples are prepared using selective laser melting(SLM)technology.By comparing the test results of the quasi-static compression test with the results of the numerical simulation,it is found that compared with the other three bionic lattice structures,the SCH structure has the best energy absorption effect in the effective stroke in the test,and the specific energy absorption can reach 6.32 J/g.ZPRH,SCH,and IBE structures not only have good and stable deformation behavior,but also have excellent impact resistance and shape memory properties.The design of these structures provides a reference for the design of anti-shock cushioning structures with self-recovery functions in the future.

Construction and Properties of Simvastatin and Calcium Phosphate Dual-Loaded Coaxial Fibrous Membranes with Osteogenic and Angiogenic Functions

The ideal Guided Bone Regeneration(GBR)membrane is required to have good biocompatibility,space maintenance ability,appropriate degradation rate,and preferably can guide the regeneration of vascularized bone tissue.In this study,Simvastatin(SIM)and calcium Phosphate(CaP)were encapsulated in a Polycaprolactone(PCL)/Chitosan(CS)core-shell structural fibrous membranes via coaxial electrospinning technology.The results showed that loaded SIM in the core of the core-shell structure fibrous membranes could sustainably release the drug for more than two months and upregulate the angiogenic marker of Bone Mesenchymal Stem Cells(BMSCs).Adding a certain amount of CaP to the shell layer provided more sites for the mineralization and synergistic with SIM to promote osteogenic differentiation of BMSCs in vitro.The intramuscular implantation experiments in rabbits suggested a normal early inflammation and enhanced vascularization induced by the SIM-loaded fibrous membranes.This study proposed an effective strategy to prepare a dual-loaded core-shell fibrous membrane for guided vascularized bone tissue regeneration.

3D Biocompatible Polyester Blend Scaffolds Containing Degradable Calcium Citrate for Bone Tissue Engineering

In this study,a novel porous 3D composite scaffold based on the biodegradable Poly(ε-caprolactone)(PCL),Polylactide Acid(PLA)and Calcium Citrate(CC)was developed via polymer blends and thermal-induced phase separation.The chemical structure,crystalline structure and micromorphology as well as mechanical strength of the scaffolds were characterized by Fourier Transform Infrared Spectroscopy(FTIR),X-ray Diffraction(XRD),Scanning Electron Microscope(SEM)and tensile tests.The results show that the obtained composite scaffold present a suitable bone-like porous structure and sufficient mechanical strength.Furthermore,the release of calcium ions in Simulated Body Fluid(SBF)indicates that the composite material can provide a stable calcium-ion environment and maintain a constant pH value during the soaking process.The cell proliferation results from CCK-8 and light microscopy show that MG63 cells exhibit excellent adhesion and proliferation on the stent.At the same time,animal implantation histology confirms that the composite scaffolds have good biocompatibility in vivo.The scaffold material has greatly potential application value in the field of bone tissue engineering.

Enhanced Butterfly Optimization Algorithm for Large-Scale Optimization Problems

To solve large-scale optimization problems,Fragrance coefficient and variant Particle Swarm local search Butterfly Optimization Algorithm(FPSBOA)is proposed.In the position update stage of Butterfly Optimization Algorithm(BOA),the fragrance coefficient is designed to balance the exploration and exploitation of BOA.The variant particle swarm local search strategy is proposed to improve the local search ability of the current optimal butterfly and prevent the algorithm from falling into local optimality.192000-dimensional functions and 201000-dimensional CEC 2010 large-scale functions are used to verify FPSBOA for complex large-scale optimization problems.The experimental results are statistically analyzed by Friedman test and Wilcoxon rank-sum test.All attained results demonstrated that FPSBOA can better solve more challenging scientific and industrial real-world problems with thousands of variables.Finally,four mechanical engineering problems and one ten-dimensional process synthesis and design problem are applied to FPSBOA,which shows FPSBOA has the feasibility and effectiveness in real-world application problems.

Novel Anti-fouling Strategies of Live and Dead Soft Corals(Sarcophyton trocheliophorum):Combined Physical and Chemical Mechanisms

At present,biomimetic antifouling research objects are mostly concentrated on the fast-moving marine organism,but the anti-fouling effect of the low-speed or static marine equipment is not obvious.This paper describes the anti-fouling mechanism of soft coral(Sarcophyton trocheliophorum),including the physical defense mechanism and the bactericidal ability of mucus and coral powder.As a sessile organisms,soft coral lacks escape mechanism.Therefore,the study on its antibacterial strategy is significant because it can provide theoretical guidance for static antifouling.Results showed that the live soft coral would molt in unfriendly environment,and the secreted mucus could defend themselves against fouling microorganism.Then,Liquid Chromatography-Mass Spectrometry(LC-MS)analysis was conducted to identify the bioactive compounds of the coral powder and mucus.Results revealed that both powder and mucus contained a wide variety of toxic components,which had bactericidal effects.Moreover,at the same concentration,the inhibitory effect of the main components on Gram-negative bacteria was stronger than that on positive bacteria.These findings enhance the understanding about the antifouling mechanism of soft coral and provide new ideas for design and prepare novel antifouling strategy to combat biofouling under static condition.

Wear Behavior of a Bio-inspired Bearing for off-center Loads

Misalignment is one of the most common causes of wear in bush bearings.Design improvements have been proposed by many researchers.Unfortunately,it did not efficiently reduce the misalignment.Classic geometrical designs sometimes reach their limits.For this reason,a bio-inspired design is proposed to solve the impediment.In this article,a bio-inspired bearing suited to misalignment was tested and compared to a classical bush bearing.The contact pressures of both bearings were compared with static Finite Element(FE)simulations for off-center load.Due to the complex shape of the involved contact,the performances of both bearings were also studied over time.Their wear behaviors were predicted with a numerical method.The methodologies emplaced to simulate the wear were described in this paper.Particularly,the wear coefficient determination obtained by experimental testing was detailed.The pressure value,the contact zone and the wear depth were compared and discussed.The wear results for the classical bearing are in accordance with the literature.The simulations show a deeper wear on the classical bush bearing than on the bio-inspired bearing.This leads to a longer period of service life for the bio-inspired bearing.

Bio-inspired Design and Evaluation of Porous Fences for Mitigating Fugitive Dust

Fugitive dust has been recognized as an important contributor to air pollution,and artificial porous fence is one of the most effective management strategies to reduce fugitive dust in open areas.To improve the shelter effects and efficiency of Particulate Matter(PM)reduction of traditional fences,this study proposed five bionic fences and their capability was evaluated through wind tunnel tests.The results indicated that all of bionic fences presented better efficiency in reducing wind speed and PM concentrations compared with traditional fences,and they were more efficient in capturing PM10.Among the bionic fences,the non-woven cloth material with four-leave opening presented the best capability both in wind speed and PM reduction.The proposed bionic fences may be further developed and studied for future application in capturing fine PM and adapting to the wind.

Wetting Transition from Hydrophilic to Superhydrophobic over Dendrite Copper Leaves Grown on Steel Meshes

With the development of water purification technologies,the usage of superhydrophobic meshes is increased but the fabrication of durable and cost effective superhydrophobic meshes is still challenging.Here,the formation of hierarchical copper fractals on stainless steel meshes and their superhydrophobicity without any physical or chemical modification were studied.In addition,the improvement of superhydrophobicity of surfaces during storing in a glass bottle for a long time(>one year)is reported.The structures were prepared using electrodeposition method applying cyclic voltammetry and square pulse deposition approaches on stainless steel meshes with 50μm,100μm and 200μm pore sizes.The prepared layers are a composition of copper with varying amounts of cuprite(Cu20)depending on deposition method and mesh pore size.As-prepared cyclic voltammetry layer on 100μm mesh showed the parahydrophobicity with the contact angle of 154°but a large sliding angle.The one-year stored samples in the glass bottle showed superhydrophobicity with the contact angles larger than 150°and sliding angles in the range of 4°-20°.The observed improvement of superhydrophobicity is a great success in the realm of industrial water purification,while most other proposed samples by the others have problems related to the durability of superhydrophobicity.

Propulsion Principles of Water Striders in Sculling Forward through Shadow Method

Semi-aquatic arthropods skate on water surfaces with synergetic actions of their legs. The sculling forward locomotion of water striders was observed and analyzed in situ to understand and reproduce the abovementioned feature. The bright-edged elliptical shadows of the six legs of a water strider were recorded to derive the supporting force distributions on legs. The propulsion principles of water striders were quantitatively disclosed. A typical sculling forward process was accomplished within approximately 0.15 s. Water striders lifted their heads slightly and supported their weight mainly by the two driving legs to increase the propulsion force and reduce the water resistance during the process. The normalized thrust-area ratio （defined as the ratio of the propulsion force to the projected area） was usually lower than 0.4 after sculling for approximately 0.08 s. The entire normal supporting force remained nearly constant during a stroke to reduce the mass center fluctuation in the normal direction. In addition, water striders could easily control the locomotion direction and speed through the light swinging of the two hind legs as rudders. These sculling principles might inspire sophisticated biomimetic wa- ter-walking robots with high propulsion efficiency in the future.

Flow Confinement Effects on the Wake Structure behind a Pitching Airfoil： A Numerical Study Using an Immersed Boundary Method

The flow patterns and wake structures behind a pitching airfoil in an un-bounded domain have been studied extensively. In contrast, the flow phenomena associated with a pitching airfoil near a solid boundary have not been adequately studied or reported. This paper aims at filling this research gap by considering the flow confinement effects on the flow pattern around a pitching airfoil. To achieve this goal, the flow fields around a flapping airfoil in un-bounded, bounded and semi-bounded domains are studied and compared. Numerical simulations are carried out at a fixed Reynolds number, Re = 255, and at a fixed oscillation frequency corresponding to St = 0.22. An accurate immersed boundary method is employed to calculate the unsteady flow fields around the airfoil at various flapping amplitudes. It is argued that two flow mechanisms, here called ＂the interaction effect＂ and ＂the induced reverse flow effect＂ are responsible for the variations of the flow field due to the presence of a nearby solid boundary.

Automated Kinematics Measurement and Aerodynamics of a Bioinspired Flapping Rotary Wing

A physical model for a micro air vehicle with Flapping Rotary Wings （FRW） is investigated by measuring the wing kine- matics in trim conditions and computing the corresponding aerodynamic force using computational fluid dynamics. In order to capture the motion image and reconstruct the positions and orientations of the wing, the photogrammetric method is adopted and a method for automated recognition of the marked points is developed. The characteristics of the realistic wing kinematics are presented. The results show that the non-dimensional rotating speed is a linear function of non-dimensional flapping frequency regardless of the initial angles of attack. Moreover, the effects of wing kinematics on aerodynamic force production and the underlying mechanism are analyzed. The results show that the wing passive pitching caused by elastic deformation can sig- nificantly enhance lift production. The Strouhal number of the FRW is much higher than that of general flapping wings, indi- cating the stronger unsteadiness of flows in FRW.

Fabrication and Testing of Self Cleaning Dry Adhesives Utilizing Hydrophobicity Gradient

In this paper we present a method to create a hydrophobicity gradient on the surface of a Polydimethylsiloxane （PDMS） dry adhesive. The method consists of the partial silanization of the surface of the dry adhesive by Chemical Vapour Deposition （CVD） of octadecyltrichlorosilane （OTS）. The partial silanization of the surface of the sample results in a hydrophobic to hy- drophilic gradient across the surface of the dry adhesive. The resulting change in hydrophobicity across the surface of the dry adhesive results in the uphill motion of a droplet of water, which appears to be directly proportional to the area of contact between the droplet and the adhesive. Normal adhesion testing is performed to quantify the effect of the hydrophobic gradient across the surface of the sample. While a variation in adhesion are only minimally affected by the silanization, and the motion strength across the sample is measured, the adhesive properties of the droplet of water doesn＇t cause any loss of adhesion.

The Gift from Nature： Bio-Inspired Strategy for Developing Innovative Bridges

Biology has been a brilliant teacher and a precious textbook to man-made construction for thousands of years, because it allows one to learn and be inspired by nature＇s remarkable and efficient structural systems. However, the emerging biomimetic studies have been of increasing interest for civil engineering design only in the past two decades. Bridge design is one of aspects on structural engineering of biomimeties that offers an enormous potential for inspiration in various aspects, such as the ge- ometry, structure, mechanism, energy use and the intelligence. Recently built bridges and design proposals in which biological systems have produced a range of inspiration are reviewed in this paper. Multidisciplinary cooperation is discussed for the implementation of bio-inspired methods in future design. A case study about using bio-inspired strategy is trying to present a problem-solving approach, yet further cooperation is still needed to utilize biomimetie studies for design inspiration. This paper aims to call a close multidisciplinary collaboration that promotes engineers to build more sustainable and smart structural systems for bridges in the 21 st century.

A Femur-Implant Model for the Prediction of Bone Remodeling Behavior Induced by Cementless Stem

Bone remodeling simulation is an effective tool for the prediction of long-term effect of implant on the bone tissue, as well as the selection of an appropriate implant in terms of architecture and material. In this paper, a finite element model of proximal femur was developed to simulate the structures of internal trabecular and cortical bones by incorporating quantitative bone functional adaptation theory with finite element analysis. Cementless stems made of titanium, two types of Functionally Graded Material （FGM） and flexible ＇iso-elastic＇ material as comparison were implanted in the structure of proximal femur respectively to simulate the bone remodeling behaviors of host bone. The distributions of bone density, von Mises stress, and interface shear stress were obtained. All the prosthetic stems had effects on the bone remodeling behaviors of proximal femur, but the degrees of stress shielding were different. The amount of bone loss caused by titanium implant was in agreement with the clinical obser- vation. The FGM stems caused less bone loss than that of the titanium stem, in which FGM I stem （titanium richer at the top to more HAP/Col towards the bottom） could relieve stress shielding effectively, and the interface shear stresses were more evenly distributed in the model with FGM 1 stem in comparison with those in the models with FGM II （titanium and bioglass） and titanium stems. The numerical simulations in the present study provided theoretical basis for FGM as an appropriate material of femoral implant from a biomechanical point of view. The next steps are to fabricate FGM stern and to conduct animal experiments to investigate the effects of FGM stem on the remodeling behaviors using animal model.

Sounds Synthesis with Slime Mould of Physarum Polycephalum

This paper introduces a novel application of bionic engineering： a bionic musical instrument using Physarum polycephalum. Physarum polycephalum is a huge single cell with thousands of nuclei, which behaves like a giant amoeba. During its foraging behavior this plasmodium produces electrical activity corresponding to different physiological states. We developed a method to render sounds from such electrical activity and thus represent spatio-temporal behavior of slime mould in a form apprehended auditorily. The electrical activity is captured by various electrodes placed on a Petri dish containing the cultured slime mold. Sounds are synthesized by a bank of parallel sinusoidal oscillators connected to the electrodes. Each electrode is responsible for one partial of the spectrum of the resulting sound. The behavior of the slime mould can be controlled to produce different timbres.