Opening up new and unlimited avenues in the biomedical field, tissue engineering and regenerative medicine, the electrospinning process is considered as a versatile and the most preferred technique for the fabrication of nanofibers. These tailor-designed nanofibers provide a desirable and bio-inspired physiological niche to cells for better attachment and subsequent proliferation. In this review, an attempt is made to explain the importance of various topological and morphological parameters of nanofibrous scaffolds for efficient bio-mimicking. Some novel approaches (e.g., appropriate functionalization and extracellular matrix derived from decellularization) util-ized for better mimicking and exponential growth of regenerating tissues are also discussed. Furthermore, this review highlights the important parameters necessary for the attachment, proliferation and differentiation of the mesenchymal stem cells for tissue regeneration. The importance of growth factors and their role after introducing the electrospinning techniques for efficient delivery and their role in the proliferation of mesenchymal stem cells in the different specific lineage (e.g., tenogenic, chondrogenic, neurogenic and osteogenic dif-ferentiation) are discussed.

As more and more social robots are applied in human-populated environments, they need an affective model to communicate with human beings naturally and believably. In addition, the model should be flexible to be applied in different areas, such as entertainment and education, and can be easily understood and operated by robot designers. To meet these requirements, we propose an affective model including emotions, moods and personality traits for social robots to mimic the affect changes of human beings. Inspired by the Plutchik’s Wheel of Emotions, we first construct an affective space which can simultaneously represent the affective concepts. According to the affective space, the model can be visualized vividly and easily understood. We then describe the interaction among these concepts to change the robot states to make the robot interact with human beings naturally and believably. By tuning the parameters of the model, it can be flexibly applied in different areas. We evaluate the proposed model in simulation and human-robot interaction experiments and the experimental results show that the model is effective.

The current study emphasizes inadequacies of earlier research findings on multi-robot navigation and offers a robust approach to guide the robots in an unknown dynamic workspace. To attain the objective, the Intelligent Water Drop (IWD) algorithm is combined with Differential Evolution (DE) in a new conceptual fashion to optimize the navigation path of multiple mobile robots. The hybrid IWD-DE, basic IWD and DE algorithms are then explored for multi-robot navigation in a dynamic workspace through simulation. The simulation outcomes demonstrate the competency of the proposed method to guide the robot in predicting the nature of the obstacle and to generate an optimal and safe trajectory in a dynamic workspace. The potency of the proposed algorithm is further validated through experimentation with fire bird robot in a real platform. The outcomes of the simulation and experimentation, by employing IWD-DE algorithm are com-pared with those of basic IWD and DE algorithm. The error estimated for Average Navigation Path Travelled (ANPT), Aggregate Navi-gation Path Deviation (ANPD) and number of turns between simulation and experimental results by employing IWD-DE is 8.96, 9.09, and 11.13, respectively while reaching 16.43, 28.61, 29.15 for IWD, and 6.66, 10.20, 14.28 for DE. The efficiency of the proposed approach is further verified with the state-of-the-art in a dynamic workspace. The outcomes reveal the efficiency and flexibility of the proposed approach in resolving the multi-robot navigation problem as compared to the state-of-the-art in a dynamic workspace.

Motion control based on biologically inspired methods, such as Central Pattern Generator (CPG) models, offers a promising technique for robot control. However, for a quadruped robot which needs to maintain balance while performing flexible movements, this technique often requires a complicated nonlinear oscillator to build a controller, and it is difficult to achieve agility by merely modifying the prede-fined limit cycle in real time. In this study, we tried to solve this problem by constructing a multi-module controller based on CPG. The different parallel modules will ensure the dynamic stability and agility of walking. In the proposed controller, a specific control task is accomplished by adding basic and superposed motions. The basic motions decide the basic foot end trajectories, which are generated by the predefined limit cycle of the CPG model. According to conventional kinematics-based design, the superposed motions are generated through different modules alter the basic foot end trajectories to maintain balance and increase agility. As a considerable stability margin can be achieved, different modules are designed separately. The proposed CPG-based controller is capable of stabilizing a walking quadruped robot and performing start and stop movements, turning, lateral movement and reversal in real time. Experiments and simula-tions demonstrate the effectiveness of the method.

The purpose of this research is to understand the aerodynamics of Flapping wing Micro Aerial Vehicles (FMAVs) flying in V-formation and how V-formation can improve the endurance of FMAVs. We tested FMAVs with two types of flapping kinematics: (1) idealized sinusoidal flapping/pitching motion, (2) actual FMAV wing deformation capture. Using the design of experiment methodology, together with an immersed boundary method numerical solver, we investigate the effects of phase angle and x, y, z separation between the wings on the FMAVs’ performance. Results show that it is possible to obtain an overall thrust and lift improvement of up to 25% and 14% respectively, or a reduction of both 19%, compared to the single wing configuration. Lastly, for certain cases, we extend another row, leading to a total of five wings. Results show that in general, the additional thrust or lift experienced by the second row of wings is also experienced by the third row of wings. Hence, this may apply to subsequent rows too.

Functional properties of biological surfaces have gained increasing interest in the last two decades, especially with regard to wetting and self-cleaning. Here, biological surfaces of arthropods (Collembola) and plants (sacred Lotus) served as models for the principle design of high temperature resistant surfaces used in blast furnaces to prevent tuyeres from melting. Tuyeres are double-walled, watercooled pipes supplying the blast furnace with hot air to keep the reduction and melting process running. Tuyere failure is mainly caused by melting of the wall after direct contact with liquid iron, resulting in the partial shut down of the blast furnace and huge energy losses. As a new approach to avoid tuyere failure we developed a new type of tuyere surface with (i) defined cone shaped indentations and (ii) a heat resistant zirconium/corundum coating with “ferrophobic” properties i.e. it forms with liquid iron of 1500 ?C a contact angle exceeding 130?. Theoretical considerations indicate that liquid iron infiltrates these indentations only partially if this contact angle and the aperture angle of the cone satisfy an inequality condition. Since heat conductivity of the remaining gas trapped inside the cones is by five orders of magnitude lower than in copper, the overall heat flow into the tuyere is substantially reduced and the outer walls are much less prone to melting. 

Inspired by nepenthes pitcher plants, Lubricant-Impregnated Surfaces (LISs) are surfaces with lubricant infused in the textures which form slippery interfaces. In this paper, we investigated slippery properties and the robustness of LISs with different micro-texture to-pologies (i.e., no textures, micro-pillar textures and micro hole textures), including original LISs and LISs rinsed by water. We measured the static contact angle, sliding angle and droplet motions on the LISs, using a contact angle instrument and a Particle Image Velocimetry (PIV) system. Similar contact angles and small sliding angles were observed on all original LISs, which indicated that an oil-layer existed on each LIS’s interface. After rinsed by water, the sliding angle increased obviously and the slip velocity decreased, which meant that the LISs slippery properties deteriorated in different degrees. Among all the LISs in our experiments, LIS with micro pillar textures has the best slippery performance and robustness before and after rinsed. We found that the LISs’ slippery properties were closely related to the states of the oil-layer on the interface, which were changed after rinsed. For the LIS with micro pillar textures, a thin layer of lubricant can sustain on the interface even after rinse, which made the droplet slide smoothly on the surface, with a lower sliding angle and a larger sliding velocity. This indicates that the proper micro-texture will enhance the slippery property and make it last longer.

Silk fibroin/xanthan scaffolds were prepared by blending silk fibroin and xanthan in the ratios 80SF:20Xa (SFX82), 60SF:40Xa (SFX64), and 50SF:50Xa (SFX55) using freeze drying method. In-vitro degradation behavior of the prepared scaffolds was studied for 37 days in phosphate buffer saline. The degradation rate was the function of silk fibroin, xanthan and β-crystallite contents in the silk fib-roin/xanthan composites. SFX82 degraded extremely slowly whereas SFX55 showed faster degradation rate. Hydrophilic xanthan was the main contributor of weight loss. SFX82 and SFX64 exhibited surface degradation whereas SFX55 showed bulk degradation which in-dicated that higher silk fibroin ratios favor surface degradation. Due to bulk degradation, SFX55 showed maximum surface roughness among the composite scaffolds. The FTIR spectrum revealed total loss of xanthan from the composites after degradation. The broad and low-intensity peaks in the FTIR spectrum of composite scaffolds confirmed reduction in β-sheet crystallite content during degradation. XRD analysis also confirmed reduction in β-sheet crystals and revealed that degraded composite scaffold had predominantly amorphous structure. The degraded scaffold showed higher porous structure than the non-degraded scaffold. The in vitro degradability testing gives a good approximation of degradation of scaffold in vivo and helps in designing a robust biopolymeric composite scaffold for tissue engi-neering.

Nano-sized hydroxyapatite (HA) particles were synthesized by sol-gel through water and ethanol based mediums of phosphoric acid (H3PO4) and calcium hydroxide (Ca(OH)2) at pH = 11 for different calcination time (1 h, 2 h, 4 h). The effects of calcination time and solution on the crystallinity, morphology and impurity phases of the HA nanoparticles were examined via Fourier Transform Infrared (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and X-ray Diffraction (XRD). It was found that crystallite size and the fraction crystallinity of the synthesized samples increased with calcination time. According to solution medium, only CaO as impurity was appeared in the water-based solvent, CaO and Ca(OH)2 impurities were appeared in the ethanol-based solvent. The lowest crystallinity was 0.92 and the highest crystallinity was 1.73 respectively, depending on the process parameters. The Ca/P atomic ratio closest to the bone was found as 1.5178. As a result, the employed water-based sol-gel processes for 1 h calcination time was de-termined as the optimum for the formation of nano-sized HA powders using calcium hydroxide and phosphoric acid.''

Mole crickets, Gryllotalpa orientalis, have a pair of fully specialized forelegs for burrowing and employ an efficient underground excavating pattern, which provides excellent biological example for design of bionic underground excavation equipment. In this study, the excavating pattern and kinematic features of mole crickets were obtained by using high-speed motion capture system and employing a transparent hydrogel as the analogue for soil. The two-dimensional motion characteristics of the forelegs of mole crickets during bur-rowing were captured and analyzed. The results show that the forelegs of the mole cricket employ a unique excavating pattern, which consists of foreword digging and horizontal expansion. We label this pattern a digging-expanding mode. An excavating cycle includes the digging and expanding motion of the forelegs, rotation caused by the midlegs and hindlegs, and forward thrust by the hindlegs. The ex-cavating motion of the left and right forelegs is alternately carried out. This study can inspire the design of bionic tunnelling mechanisms and underground excavation equipment.

The mechanical properties and structures of fish scales have generated considerable research interest, however, comparative studies for different fish scales from different water regions have not been reported. In this paper, the surface morphologies, hierarchical structures and mechanical properties of four kinds of fish scales collected from freshwater, shallow sea, and deep sea in New Zealand are investigated. The results indicate that the surface morphologies of those fish scales are similar at ventro-lateral, dorso-lateral and anterior locations, and the hierarchical structures of those fish scales all consist of two layers: a bone layer and a collagen layer composed of collagen fibrils. However, the spiral angles of the collagen lamellaes of different scales are different. The largest are Mugil cephalus scales, while the smallest are Cyprinus carpio scales. Comparing the mechanical behaviors of those fish scales, the tensile strength of Carassius auratus scales is the largest, but the ductility is the lowest. Pristipomoides sieboldii scales have the best ductility. Further, the relationship between hierarchical structures and mechanical properties of fish scales is discussed. It is found that the spiral angles of the collagen lamellaes and bond/collagen thickness ratio both have a great influence on the mechanical properties of fish scales. 

Utilization of biochar in plastic based blends offers a sustainable way to renewable materials as well as value-added use of wood waste. To investigate the interfacial compatibility and weatherability properties of biochar composites, four types of Wood-Plastic Composites (WPC) were prepared by an extrusion process. The mechanical properties, water absorptions, thermal and viscoelastic properties, and rheological behavior of the composites were also evaluated. The decolorizing carbon (NA) composite melts showed the higher modulus and viscosity, indicating better melt strength. The NA composites performed the best in tensile properties (strength of 
28.6 MPa and modulus of 3.4 GPa) and had strong interfacial interaction between particles and the matrix. The degree of HDPE crystal-linity in the biochar and carbon composites decreased relative to Douglas-fir (DF) composites, while the thermal properties of the com-posites improved compared with DF composites. For the water resistance, the DF composites displayed the highest water absorption (3.7%) and thickness swell (2.9%). During accelerated weathering tests, longer exposure time increased the color change and lightness, especially for DF composite. NA and biochar composites resulted in improved photostability. This study opens up a pathway to utilize effectively the renewable biochar as reinforcing filler in WPC in outdoor applications.

Cloud computing has attracted significant interest due to the increasing service demands from organizations offloading computa-tionally intensive tasks to datacenters. Meanwhile, datacenter infrastructure comprises hardware resources that consume high amount of energy and give out carbon emissions at hazardous levels. In cloud datacenter, Virtual Machines (VMs) need to be allocated on various Physical Machines (PMs) in order to minimize resource wastage and increase energy efficiency. Resource allocation problem is NP-hard. Hence finding an exact solution is complicated especially for large-scale datacenters. In this context, this paper proposes an En-ergy-oriented Flower Pollination Algorithm (E-FPA) for VM allocation in cloud datacenter environments. A system framework for the scheme was developed to enable energy-oriented allocation of various VMs on a PM. The allocation uses a strategy called Dynamic Switching Probability (DSP). The framework finds a near optimal solution quickly and balances the exploration of the global search and exploitation of the local search. It considers a processor, storage, and memory constraints of a PM while prioritizing energy-oriented allocation for a set of VMs. Simulations performed on MultiRecCloudSim utilizing planet workload show that the E-FPA outperforms the Genetic Algorithm for Power-Aware (GAPA) by 21.8%, Order of Exchange Migration (OEM) ant colony system by 21.5%, and First Fit Decreasing (FFD) by 24.9%. Therefore, E-FPA significantly improves datacenter performance and thus, enhances environmental sus-tainability.