120 research outputs found
Developing Decentralised Resilience to Malicious Influence in Collective Perception Problem
In collective decision-making, designing algorithms that use only local
information to effect swarm-level behaviour is a non-trivial problem. We used
machine learning techniques to teach swarm members to map their local
perceptions of the environment to an optimal action. A curriculum inspired by
Machine Education approaches was designed to facilitate this learning process
and teach the members the skills required for optimal performance in the
collective perception problem. We extended upon previous approaches by creating
a curriculum that taught agents resilience to malicious influence. The
experimental results show that well-designed rules-based algorithms can produce
effective agents. When performing opinion fusion, we implemented decentralised
resilience by having agents dynamically weight received opinion. We found a
non-significant difference between constant and dynamic weights, suggesting
that momentum-based opinion fusion is perhaps already a resilience mechanism.Comment: 14 Pages, 14 Figure
A mini review focused on the proangiogenic role of silicate ions released from silicon-containing biomaterials
Angiogenesis is considered an important issue in the development of biomaterials for the successful regeneration of tissues including bone. While growth factors are commonly used with biomaterials to promote angiogenesis, some ions released from biomaterials can also contribute to angiogenic events. Many silica-based biomaterials have been widely used for the repair and regeneration of tissues, mainly hard tissues such as bone and tooth structure. They have shown excellent performance in bone formation by stimulating angiogenesis. The release of silicate and others (Co and Cu ions) has therefore been implicated to play critical roles in the angiogenesis process. In this short review, we highlight the in vitro and in vivo findings of angiogenesis (and the related bone formation) stimulated by the various types of silicon-containing biomaterials where silicate ions released might play essential roles. We discuss further the possible molecular mechanisms underlying in the ion-induced angiogenic events
SIS/aligned fibre scaffold designed to meet layered oesophageal tissue complexity and properties
With donor organs not readily available, the need for a tissue-engineered oesophagus remains high, particularly for congenital childhood conditions such as atresia. Previous attempts have not been successful, and challenges remain. Small intestine submucosa (SIS) is an acellular matrix material with good biological properties; however, as is common with these types of materials, they demonstrate poor mechanical properties. In this work, electrospinning was performed to mechanically reinforce tubular SIS with polylactic-co-glycolic acid (PLGA) nanofibres. It was hypothesised that if attachment could be achieved between the two materials, then this would (i) improve the SIS mechanical properties, (ii) facilitate smooth muscle cell alignment to support directional growth of muscle cells and (iii) allow for the delivery of bioactive molecules (VEGF in this instance). Through a relatively simple multistage process, adhesion between the layers was achieved without chemically altering the SIS. It was also found that altering mandrel rotation speed affected the alignment of the PLGA nanofibres. SIS-PLGA scaffolds performed mechanically better than SIS alone; yield stress improvement was 200% and 400% along the longitudinal and circumferential directions, respectively. Smooth muscle cells cultured on the aligned fibres showed resultant unidirectional alignment. In vivo the SIS-PLGA scaffolds demonstrated limited foreign body reaction judged by the type and proportion of immune cells present and lack of fibrous encapsulation. The scaffolds remained intact at 4 weeks in vivo, and good cellular infiltration was observed. The incorporation of VEGF within SIS-PLGA scaffolds increased the blood vessel density of the surrounding tissues, highlighting the possible stimulation of endothelialisation by angiogenic factor delivery. Overall, the designed SIS-PLGA-VEGF hybrid scaffolds might be used as a potential matrix platform for oesophageal tissue engineering. In addition to this, achieving improved attachment between layers of acellular matrix materials and electrospun fibre layers offers the potential utility in other applications. STATEMENT OF SIGNIFICANCE: Because of its multi-layered nature and complex structure, the oesophagus tissue poses several challenges for successful clinical grafting. Therefore, it is promising to utilise tissue engineering strategies to mimic and form structural compartments for its recovery. In this context, we investigated the use of tubular small intestine submucosa (SIS) reinforced with polylactic-co-glycolic acid (PLGA) nanofibres by using electrospinning and also, amongst other parameters, the integrity of the bilayered structure created. This was carried out to facilitate smooth muscle cell alignment, support directional growth of muscle cells and allow the delivery of bioactive molecules (VEGF in this study). We evaluated this approach by using in vitro and in vivo models to determine the efficacy of this new system
Nano-graphene oxide/polyurethane nanofibers: mechanically flexible and myogenic stimulating matrix for skeletal tissue engineering
For skeletal muscle engineering, scaffolds that can stimulate myogenic differentiation of cells while possessing suitable mechanical properties (e.g. flexibility) are required. In particular, the elastic property of scaffolds is of importance which helps to resist and support the dynamic conditions of muscle tissue environment. Here, we developed highly flexible nanocomposite nanofibrous scaffolds made of polycarbonate diol and isosorbide-based polyurethane and hydrophilic nano-graphene oxide added at concentrations up to 8%. The nano-graphene oxide incorporation increased the hydrophilicity, elasticity, and stress relaxation capacity of the polyurethane-derived nanofibrous scaffolds. When cultured with C2C12 cells, the polyurethane–nano-graphene oxide nanofibers enhanced the initial adhesion and spreading of cells and further the proliferation. Furthermore, the polyurethane–nano-graphene oxide scaffolds significantly up-regulated the myogenic mRNA levels and myosin heavy chain expression. Of note, the cells on the flexible polyurethane–nano-graphene oxide nanofibrous scaffolds could be mechanically stretched to experience dynamic tensional force. Under the dynamic force condition, the cells expressed significantly higher myogenic differentiation markers at both gene and protein levels and exhibited more aligned myotubular formation. The currently developed polyurethane–nano-graphene oxide nanofibrous scaffolds, due to their nanofibrous morphology and high mechanical flexibility, along with the stimulating capacity for myogenic differentiation, are considered to be a potential matrix for future skeletal muscle engineering
Gelatin-apatite bone mimetic co-precipitates incorporated within biopolymer matrix to improve mechanical and biological properties useful for hard tissue repair
Synthetic biopolymers are commonly used for the repair and regeneration of damaged tissues. Specifically targeting bone, the composite approach of utilizing inorganic components is considered promising in terms of improving mechanical and biological properties. We developed gelatin-apatite co-precipitates which mimic the native bone matrix composition within poly(lactide-co-caprolactone) (PLCL). Ionic reaction of calcium and phosphate with gelatin molecules enabled the co-precipitate formation of gelatin-apatite nanocrystals at varying ratios. The gelatin-apatite precipitates formed were carbonated apatite in nature, and were homogeneously distributed within the gelatin matrix. The incorporation of gelatin-apatite significantly improved the mechanical properties, including tensile strength, elastic modulus and elongation at break, and the improvement was more pronounced as the apatite content increased. Of note, the tensile strength increased to as high as 45 MPa (a four-fold increase vs. PLCL), the elastic modulus was increased up to 1500 MPa (a five-fold increase vs. PLCL), and the elongation rate was ∼240% (twice vs. PLCL). These results support the strengthening role of the gelatin-apatite precipitates within PLCL. The gelatin-apatite addition considerably enhanced the water affinity and the acellular mineral-forming ability in vitro in simulated body fluid; moreover, it stimulated cell proliferation and osteogenic differentiation. Taken together, the GAp-PLCL nanocomposite composition is considered to have excellent mechanical and biological properties, which hold great potential for use as bone regenerative matrices
Delivery of dexamethasone from bioactive nanofiber matrices stimulates odontogenesis of human dental pulp cells through integrin/BMP/mTOR signaling pathways
Biomedical applications of natural-based polymers combined with bioactive glass nanoparticles
In recent years, the combination of natural polymers with nanoparticles has permitted the development
of sophisticated and efficient bioinspired constructs. In this regard, the incorporation of bioactive glass
nanoparticles (BGNPs) confers a bioactive nature to these constructs, which can then induce the
formation of a bone-like apatite layer upon immersion in a physiological environment. Moreover, the
incorporation of bioactive glass nanoparticles has been found to be beneficial; the constructs proved to
be biocompatible, promote cell adhesion and spreading, and regulate osteogenic commitment. This
review provides a summary and discussion of the composition, design, and applications of bioinspired
nanocomposite constructs based on BGNPs. Examples of nanocomposite systems will be highlighted
with relevance to biomedical applications. It is expected that understanding the principles and the stateof-the-art
of natural nanocomposites may lead to breakthroughs in many research areas, including tissue
engineering and orthopaedic devices. The challenges regarding the future translation of these nanostructured
composites into clinical use are also summarized.A´lvaro J. Leite acknowledges the Portuguese Foundation for Science
and Technology (FCT) for his doctoral grant (SFRH/BD/73174/2010).info:eu-repo/semantics/publishedVersio
Nano/micro-structured poly(ϵ-caprolactone)/gelatin nanofibers with biomimetically-grown hydroxyapatite spherules: High protein adsorption, controlled protein delivery and sustained bioactive ions release designed as a multifunctional bone regenerative membrane
A computational linguistic approach for the identification of translator stylometry using Arabic-English text
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