Scaffolds are of great importance in tissue engineering applications as they provide a mechanically supportive environment for cellular activity, which is particularly necessary for hard tissues such ...as bone. Notably, the mechanical properties of a scaffold vary with differing design parameters such as those related to scaffold height and internal structure. Thus, the present study aimed to explore the relationship between design parameters and mechanical properties of composite polycaprolactone (PCL) and nano-hydroxyapatite (nHAp) scaffolds fabricated by three-dimensional (3D) printing.
We designed and printed scaffolds with different internal structures (lattice and staggered) and varying heights (4, 6, 8 and 10 layers), and consistent porosity (50%) for the purpose of comparison. Then, we examined the scaffold microstructure (pore size and penetration between layers) using scanning electron microscopy (SEM) and mechanical properties (elastic modulus and yield strength) using compressive testing.
Our results illustrated that the microstructural parameters were related to scaffold design. At higher heights, pore size increased while penetration between layers decreased; thus, mechanical properties were affected. Results of mechanical testing demonstrated that for lattice scaffolds, elastic modulus was similar for 6 vs 4, and 8 vs 4 layers but ~33% lower for 10 layers vs 4 layers. Similarly, yield strength was comparable for 6 vs 4, and 8 vs 4 layers but ~27% lower for 10 layers vs 4 layers. With staggered scaffolds, when compared to 4-layer results, elastic modulus was similar for 6 layers but was ~43% lower for 8 layers and ~38% lower for 10 layers. Staggered scaffolds had ~38%, ~51%, and ~76% lower yield strength when the number of layers were increased from 4 to 6, 8, and 10 layers, respectively. When comparing lattice and staggered scaffolds with the same layer number, elastic modulus was similar, apart from 8-layer scaffolds where the staggered design was ~42% lower than lattice. Yield strength was similar between 4-layer staggered and lattice scaffolds, while staggered scaffolds with 6, 8, and 10 number of layers showed ~43%, ~45%, ~68% lower strength, respectively, than those found in lattice scaffolds with the same layer numbers.
Mechanical properties of 3D printed scaffolds depended on scaffold height for both lattice and staggered internal structures. Staggered scaffolds had lower mechanical properties than the lattice scaffolds with the same height and were more sensitive to the change in scaffold height. Taken together, lattice scaffolds demonstrated the advantages of more stable mechanical properties over staggered scaffolds. Also, scaffolds with lower height were more promising in terms of mechanical properties compared to scaffolds with greater height.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Path planning algorithms are used by mobile robots, unmanned aerial vehicles, and autonomous cars in order to identify safe, efficient, collision-free, and least-cost travel paths from an origin to a ...destination. Choosing an appropriate path planning algorithm helps to ensure safe and effective point-to-point navigation, and the optimal algorithm depends on the robot geometry as well as the computing constraints, including static/holonomic and dynamic/non-holonomically-constrained systems, and requires a comprehensive understanding of contemporary solutions. The goal of this paper is to help novice practitioners gain an awareness of the classes of path planning algorithms used today and to understand their potential use cases—particularly within automated or unmanned systems. To that end, we provide broad, rather than deep, coverage of key and foundational algorithms, with popular algorithms and variants considered in the context of different robotic systems. The definitions, summaries, and comparisons are relevant to novice robotics engineers and embedded system developers seeking a primer of available algorithms.
Researchers are drawn to Wireless Sensor Networks (WSNs) due to its versatility and possible use cases in a variety of fields, including target tracking and identification environmental sensing, ...industrial process tracking, and tactical systems. Recently, there has been a lot of focus on the particular issues that arise from implementing routing in sensor networks as opposed to the more conventional data routing in wireless connections. Due to the importance of energy conservation in the design of WSNs, numerous protocols for routing, power management, and data transmission have been developed for these networks. When it comes to environmental monitoring, traffic monitoring, etc., routing in WSNs is crucial. The primary objective of this study is to analyse routing issues and to analyse routing-related optimization issues. Features pertaining to routing issues like energy consumption, security, speed, and dependability are explored later. Attention has been paid to the routing protocols, which might vary by use case and network design. In this study, a comprehensive review is performed on the cutting-edge approaches to routing in WSNs. A brief introduction to WSNs and a discussion of the obstacles that routing protocols must overcome throughout their creation before moving on to a thorough examination of the various routing approaches now in use is considered. The comparative analysis is performed different routing techniques like Energy-Aware Routing for Software-Defined Multihop Wireless Sensor Networks (EAR-SDMWSN), DORA: A Destination-Oriented Routing Algorithm for Energy-Balanced Wireless Sensor Networks (DORA) and Energy Proficient Load Balancing Routing Scheme for Wireless Sensor Networks (EP-LBR). The benefits and drawbacks of each routing method, with an emphasis on performance is also performed.
Wireless Sensor Networks (WSNs) are networks of low-power, low-cost devices that may gather data for many applications. These networks rely heavily on Medium Access Control (MAC) features for ...administration due to the critical roles of energy and security. Due to the low resources of the nodes, traditional security methods are unsuitable for WSNs, hence lightweight cryptographic algorithms are required to ensure adequate security. Nodes, which are communication devices in WSNs, are used. Data trust, data availability, authentication, and data integrity are just some of the security concerns raised by the deployment of such nodes. To address these concerns and ensure secure data transmission, cryptographic methods should be utilized. Keeping information transmitted over a wireless sensor network secure is complicated by the technology's increasing popularity. The problem arises because of the constraints imposed by finite supplies of energy, data storage, and processing power. This research offers a method for node validations in WSN for secure data transmission, taking into account the characteristics of wireless sensor nodes where the energy consumption for transferring data is substantially larger than that for calculation. Cryptography keys will be used for node authentication and for secure data transmission. Messages sent between nodes in a WSN must be encrypted, and the network must keep a key for encryption and decryption. As a result, Key management plays a crucial role in ensuring WSN safety. Each node will be allocated with a key set which is used for node validation, encryption and decryption. Secure and efficient data transmission in WSN relies on obtaining such a key arrangement in a constrained resource setting. Plaintext assaults, attacks using brute force, attacks via side channels, and computational complexity are just a few of the security problems that plague today's algorithms. This research presents a scheme for protecting sensor data during transmission and after it has been received by nodes. This research proposes a Exceptional Key based Node Validation for Secure Data Transmission using Asymmetric Cryptography (EKbNV-SDT-AC) model. This research performs node validation, encryption and decryption of data in the WSN to securely transmit the data from source to destination. The proposed model when compared with the traditional model performs better in data node validation and secure data transmission.
Approximately eight decades ago, during World War II, the concept of intelligent robots capable of independent arm movement began to emerge as computer science and electronics merged with ...advancements in mechanical engineering. This marked the starting point of a thriving industry focused on research and development in mobile robotics. In recent years, there has been a growing association between robotics and artificial intelligence, aiming to enable robots to make autonomous decisions akin to human cognition. To achieve this objective, researchers are actively exploring the integration of artificial neural networks with mechatronic robots. These intelligent and self-decision-making robots possess the potential to revolutionize human capabilities and elevate our intelligence to unprecedented levels. In various physical service sectors such as cleaning, security, and other tasks that don't require creative or analytical thinking, these robots can efficiently carry out the assigned responsibilities. Moreover, robots have the potential to play a significant role in military operations, eliminating the need for human lives to be sacrificed in warfare. This review article aims to explore the advancements in mobile robotics since their inception nearly 80 years ago. It will delve into the detailed applications of these robots across different sectors and discuss their profound effects on contemporary human lives and industrial landscapes.
Functional electrical stimulation (FES) is a potential neurorehabilitative intervention to enable functional movements in persons with neurological conditions that cause mobility impairments. ...However, the quick onset of muscle fatigue during FES is a significant challenge for sustaining the desired functional movements for more extended periods. Therefore, a considerable interest still exists in the development of sensing techniques that reliably measure FES-induced muscle fatigue. This study proposes to use ultrasound (US) imaging-derived echogenicity signal as an indicator of FES-induced muscle fatigue. We hypothesized that the US-derived echogenicity signal is sensitive to FES-induced muscle fatigue under isometric and dynamic muscle contraction conditions. Eight non-disabled participants participated in the experiments, where FES electrodes were applied on their tibialis anterior (TA) muscles. During a fatigue protocol under either isometric and dynamic ankle dorsiflexion conditions, we synchronously collected the isometric dorsiflexion torque or dynamic dorsiflexion angle on the ankle joint, US echogenicity signals from TA muscle, and the applied stimulation intensity. The experimental results showed an exponential reduction in the US echogenicity relative change (ERC) as the fatigue progressed under the isometric (R2=0.891±0.081) and dynamic (R2=0.858±0.065) conditions. The experimental results also implied a strong linear relationship between US ERC and TA muscle fatigue benchmark (dorsiflexion torque or angle amplitude), with R2 values of 0.840±0.054 and 0.794±0.065 under isometric and dynamic conditions, respectively. The findings in this study indicate that the US echogenicity signal is a computationally efficient signal that strongly represents FES-induced muscle fatigue. Its potential real-time implementation to detect fatigue can facilitate an FES closed-loop controller design that considers the FES-induced muscle fatigue.
Ulcerative colitis is a colonic disease characterized by the disruption of the mucosal epithelial layer and inflammation. For the treatment of this disease, various chemotherapeutic agents are ...available. However, the toxicities associated with chemotherapeutics greatly hamper treatment. Polysaccharide from natural resources is emerging as a potentially therapeutic substance with comparative minimum adverse effects. In this article, we are discussing polysaccharide from diverse sources (plants, edible mushrooms, and algae) which are being used in the treatment of ulcerative colitis. These polysaccharides exert their therapeutic action on ulcerative colitis through several mechanisms, including suppression of inflammatory cascades NF-ĸB, MAPK, IL-6/JAK2/STAT3, preventing the release of certain inflammatory mediators, modulating the intestinal microbiome, maintaining the integrity of intestinal barriers, and regulating the certain inflammatory markers. The present review compiles the role of different polysaccharides being used successfully in the management/treatment of ulcerative colitis. Special emphasis was given to explaining the biomolecular pathway.
Abstract Background: Management of open neural tube defects is challenging and the outcome is demanding. Aims: The aim of this study was to analyze the outcomes in open neural tube defects. Material ...and Methods: The data between June 2017 and December 2022 were analyzed. Those with incomplete data, not giving consent, or lost to follow-up were excluded. All underwent closure using primary closure, Z plasty, or rhomboid flap. Dura closure was achieved with native dura augmented with thoracolumbar fascia. The outcome was analyzed with respect to the duration of surgery, blood loss, requirement of Z plasty/rhomboid flaps for closure, wound infection, flap blackening, CSF leak, and features of sepsis. Result: In total, 164 of 243 cases formed the study group. The mean age at presentation was 4 days (range 0–28 days). The mean duration of surgery after presentation was 2 days (range 1–3 days). Mean operating time was 1.15 hours (range 0.45–3.15 h). Hydrocephalous was present in 146 cases and all required VP shunt. Lower limb paraplegia and spasticity were present in 63 and 23 cases. Skin closure was achieved by primary closure in 23, double Z plasty in 76, and rhomboid flap in 65 cases. Wound infection and blackening of flap were seen in 13 and 1 case in double Z pasty and 6 and 7 cases in the rhomboid flap group, respectively ( P = 0.7). CSF leak was seen in 8 cases. Wound dehiscence and sepsis were seen in 10 and 28 cases, respectively. Conclusion: Management of open neural tube defects requires adequate planning. CSF shunting and flap/Z plasty is often required.
The concept of protein intrinsic disorder has taken the driving seat to understand regulatory proteins in general. Reports suggest that in mammals nearly 75% of signalling proteins contain long ...disordered regions with greater than 30 amino acid residues. Therefore, intrinsically disordered proteins (IDPs) have been implicated in several human diseases and should be considered as potential novel drug targets. Moreover, intrinsic disorder provides a huge multifunctional capability to hub proteins such as c-Myc and p53. c-Myc is the hot spot for understanding and developing therapeutics against cancers and cancer stem cells. Our past understanding is mainly based on in vitro and in vivo experiments conducted using c-Myc as whole protein. Using the reductionist approach, c-Myc oncoprotein has been divided into structured and disordered domains. A wealth of data is available dealing with the structured perspectives of c-Myc, but understanding c-Myc in terms of disordered domains has just begun. Disorderness provides enormous flexibility to proteins in general for binding to numerous partners. Here, we have reviewed the current progress on understanding c-Myc using the emerging concept of IDPs.
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