A Numerical Investigation of Bio-inspired Scaffolds and Surface Textures

Synthetic scaffolds are widely used as implants to repair bone fracture. Without a proper design, scaffolds could pose significant health risks to the patient and fail to heal the bone properly. A good synthetic scaffold needs to have high porosity and large pore size to allow new bone cells to form on it. However, a scaffold with higher porosity and larger pore size tends to have reduced mechanical strength. Thus, it is important to find a structural design which allows the implant to have a high porosity and large pore size while retaining high strength. In this research, a 3D-printable bio-inspired structure based on the unit cell of hydroxyapatite (HAp), along with several other common scaffold structures, were designed and tested using a multiscale approach. Those structures are tested under different loading conditions to find the stress levels. HAp material properties are extracted from the density functional theory calculations, and the effect of porosity on the material properties are modeled based on empirical relations by utilizing the density as the scaling factor. The results show that the HAp-inspired scaffold could have up to 70% lower stress level when compared to other common scaffold designs，such as round or square pores scaffolds, under the same loading condition. Due to substitutions during aging, the scaffolds made of apatite can be significantly different from stoichiometric HAp. Hence, this study is also extended to test the HAp-inspired scaffold with varying anionic and cationic substitutions, including Mg2+, Zn2+, and CO32-. Furthermore, the surface texture of synthetic scaffolds has also become an important research subject in the last decade. Studies have found that surface texture can alter surface properties, such as cell adhesion, protein adsorption, and coefficient of friction, of a biomaterial. In this study, two of very promising 3D-printable bio-inspired surface textures are studied for their stress reaction under a loading condition. Some advice that could lead to a structurally stronger surface texture design is concluded. This study will provide an insight into a better scaffold design based on bio-inspired structures and the effects of substitutions on HAp scaffolds

a solution framework on fundamentals in model transformation

IEEE Computer Society; Int. Association for Computer and Information Science (ACIS)With the great achievements and successes in model transformations (MT), we propose to study MTs from an open and general cognitive background which differs from most current practice. Issues under study cover the broad scope of openness, incompleteness

Design and Performance Analysis of Probabilistically Shaped QAM Signals for Coherent FSO Systems with Gamma-Gamma Turbulence Channels

Probabilistic shaping (PS) is a promising technique to approach the Shannon limit. In this paper, we design a practical coded modulation scheme based on PS to improve the capacity of coherent free-space optical (FSO) links with quadrature amplitude modulation (QAM), where the fading channel follows the Gamma-Gamma distribution. The aim of this paper is to optimize the probability mass function (PMF) of the QAM signal points to achieve the maximum channel capacity. Due to the complexity of the objective function, the heuristic algorithm was employed to solve the optimization problem. To the best of the authors’ knowledge, the closed-form pairwise error probability (PEP) is first derived with the non-uniform signals under the turbulence channel. In addition, we measure the average symbol error rate (SER) and post-FEC bit error rate (BER) by the Monte Carlo simulation method. The numerical simulation results of both capacity and BER show that the proposed PS scheme is better than the uniform distribution. The post-FEC BER results show that the proposed PS scheme provides significant gains compared with the uniform scheme

Presentation1_Effect of curcumin nanoparticles on proliferation and migration of mouse airway smooth muscle cells and airway inflammatory infiltration.PPTX

Curcumin (CUR) possesses the capability to inhibit various inflammatory factors, exert anti-inflammatory effects, and alleviate asthma attacks; however, its hydrophobicity and instability significantly impede its clinical application. In this study, we synthesized CUR-loaded nanoparticles (CUR-NPs) and evaluated their impact on the proliferation, migration, and inflammatory infiltration of mouse airway smooth muscle cells (ASMCs), while investigating their underlying mechanisms. To achieve this objective, ASMCs were isolated from BALB/c mice and subjected to TGF-β1-induced cell proliferation and migration. Our findings demonstrate that CUR-NPs effectively regulate the release of CUR within cells with superior intracellular uptake compared to free CUR. The CCK-8 assay results indicate that the blank carrier does not exhibit any cytotoxic effects on cells, thus rendering the impact of the carrier itself negligible. The TGF-β1 group exhibited a significant increase in cell proliferation, whereas treatment with CUR-NPs significantly suppressed TGF-β1-induced cell proliferation. The findings from both the cell scratch assay and transwell assay demonstrated that TGF-β1 substantially enhanced cell migration, while CUR-NPs treatment effectively attenuated TGF-β1-induced cell migration. The Western blot analysis demonstrated a substantial increase in the expression levels of TGF-β1, p-STAT3, and CTGF in ASMCs following treatment with TGF-β1 when compared to the control group. Nevertheless, this effect was effectively counteracted upon administration of CUR-NPs. Furthermore, an asthma mouse model was successfully established and CUR-NPs were administered through tail vein injection. The serum levels of TGF-β1 and the expression levels of TGF-β1, p-STAT3, and CTGF proteins in the lung tissue of mice in the model group exhibited significant increases compared to those in the control group. However, CUR-NPs treatment effectively attenuated this change. Our research findings suggest that CUR-NPs possess inhibitory effects on ASMC proliferation, migration, and inflammatory infiltration by suppressing activation of the TGF-β1/p-STAT3/CTGF signaling pathway, thereby facilitating inhibition of airway remodeling.</p

Modulation Format Identification in a Satellite to Ground Optical Wireless Communication Systems Using a Convolution Neural Network

The satellite-to-ground communication system is a significant part of future space communication networks. The free-space optical (FSO) communication technique is a prospective solution for satellite-to-ground communication. However, atmospheric optical turbulence is a major impairment in FSO communication systems. In this paper, to improve the performance and flexibility of a satellite-to-ground laser communication system, we put forward a novel modulation format identification (MFI) technique for an FSO communication system based on a convolution neural network (CNN). The results indicate that our CNN model can blindly and accurately identify the modulation format with classification accuracy up to 99.98% for random channel condition, including the strength of turbulence and signal-to-noise ratio (SNR) of additive Gaussian white noise (AWGN) ranging from 10dB to 30dB. Moreover, the CNN demonstrated robustness against atmospheric optical turbulence and suggested immunity to additive noise. Therefore, the proposed methodology proved to be a viable solution in the application of an FSO communication simulation channel, which can easily deal with the scene of fast modulation format switching and accurate identification to satisfy system requirements. Therefore, we hope this scheme can find a practical implementation in satellite-to-ground optical wireless systems

Processing induced nanoscale heterogeneity impact on the mechanical and electrical behavior of Cu–Zr thin film metallic glasses

The variation of structural heterogeneity at the nanoscale can significantly impact the mechanical and electrical properties of thin film metallic glasses (TFMGs). Such nanoscale heterogeneity is closely related to the diverse atomic configurations in the amorphous structure, which are influenced by TFMGs processing history. In this study, we investigate the impact of processing-induced local nanoscale heterogeneity of TFMGs on the mechanical and electrical properties by tuning the sputtering targets, e.g., single CuZr target vs. co-sputtering of Cu and Zr target to tune the nanoscale heterogeneity. Specifically, Cu50Zr50 TFMGs are synthesized by sputtering a single CuZr target (single-CuZr) and co-sputtering Cu and Zr target (co-CuZr), respectively. The varying nanoscale heterogeneity was determined via a dynamic atomic force microscopy measurement. The single-CuZr, possessing nanoscale heterogeneity with ∼25.9% less correlation length, are found to have ∼28.5% higher modulus, and ∼6.1% higher hardness than those of co-CuZr TFMGs. Under the heat treatment at the same temperature (573 K), the difference in nanoscale heterogeneity makes the two films exhibit opposite manner, with the relaxation of single-CuZr and rejuvenation of co-CuZr, leading to a variation in the electrical and mechanical behaviors of TFMGs. Our work implies the significance of the processing-dependent structural heterogeneity at the nanoscale of TFMGs, which could be used to tailor the TFMGs for multifunctional applications

distinguishing between automatic and manual aspects of model driven development

IEEE Comp Soc, Univ Potsdam, Hasso Plattner Inst Software Syst EngnManual portion and automatable aspects are often not explicitly differentiated and defined in most model driven software development (AdDSD). This may hinder the advancement of the automation level of AMSD with problems such as defining the b

The Polarization States of Microglia in TBI: A New Paradigm for Pharmacological Intervention

Traumatic brain injury (TBI) is a serious medical and social problem worldwide. Because of the complex pathophysiological mechanisms of TBI, effective pharmacotherapy is still lacking. The microglial cells are resident tissue macrophages located in the brain and have two major polarization states, M1 phenotype and M2 phenotype, when activated. The M1 phenotype is related to the release of proinflammatory cytokines and secondary brain injury, while the M2 phenotype has been proved to be responsible for the release of anti-inflammation cytokines and for central nervous system (CNS) repair. In animal models, pharmacological strategies inhibiting the M1 phenotype and promoting the M2 phenotype of microglial cells could alleviate cerebral damage and improve neurological function recovery after TBI. In this review, we aimed to summarize the current knowledge about the pathological significance of microglial M1/M2 polarization in the pathophysiology of TBI. In addition, we reviewed several drugs that have provided neuroprotective effects against brain injury following TBI by altering the polarization states of the microglia. We emphasized that future investigation of the regulation mechanisms of microglial M1/M2 polarization in TBI is anticipated, which could contribute to the development of new targets of pharmacological intervention in TBI