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Hydroxyapatite (HAp) is a popular ceramic biomaterial, which has extensively been employed in numerous biomedical applications. It has drawn the attention of scientists primarily owing to its properties similar to the bones and teeth of human beings. Due to its organic similarity, HAp has exceptional biocompatibility and can activate osteoconduction and osteoinduction occurrence. Hence, HAp has been used in a broad collection of healing applications extending from common dental implant, and bioactive coatings on grafts to purposefully premeditated drug delivery methods, and even for tissue engineering (TE) applications. The production method is essential in controlling the physicochemical properties of HAp, which in turn affects its mechanical and biological properties. The anticipated physiognomies of HAp can be accomplished using a suitable technique of production and sources. This in-depth review discussed the various natural sources of HAp, and synthesis techniques for producing HAp, alongside their advantages and disadvantages, applications, and essentials of HAp for therapeutic applications. From the review, it was found that the sol–gel route is preferred over other routes because of its even molecular mixing, high purity of products, low production temperature, and ability to synthesize nanosized particles of HAp. As a result, it is provisional that upon the cautious blend of key considerations such as sources, synthesis technique, and production parameters for the manufacture of natural HAp (NHAp), mechanical properties can be improved and the product can be employed as a drug delivery system. These are important extents for the prospect of the research.

Quadcopter unmanned aerial vehicle is a multivariable, coupled, unstable, and underactuated system with inherent nonlinearity. It is gaining popularity in various applications and has been the subject of numerous research studies. However, modelling and controlling a quadcopter to follow a trajectory is a challenging issue for which there is no unique solution. This study proposes an optimal hybrid quadcopter control with MPC-based backstepping control for following a reference trajectory. The outer-loop controller (backstepping controller) regulates the quadcopter’s position, whereas the inner-loop controller (Model Predictive Control) regulates its attitude. The translational and rotational dynamics of the quadcopter are analyzed utilizing the Newton-Euler method. After that, the backstepping controller (BC) is created, which is a recurrent control method according to Lyapunov’s theory that utilizes a genetic algorithm (GA) to choose the controller parameters automatically. In order to apply a linear control technique in the presence of nonlinearities in the quadcopter dynamics, Linear Parameter Varying (LPV) Model Predictive Control (MPC) structure is developed. Simulation validated the dynamic performance of the proposed optimal hybrid MPC-based backstepping controller of the quadcopter in following a given reference trajectory. The simulations demonstrate the fact that using a command control input in trajectory tracking, the proposed control algorithm offers suitable tracking over the assigned position references with maximum appropriate tracking errors of 0.1 m for the �� and �� positions and 0.15 m for the �� position.

As global demand for sustainable biomass and need to mitigate global warming begin to rise, cultivation of seaweed has gained significant attention in recent years due to its potential for carbon recycling. However, limited availability of suitable coastal areas for large-scale seaweed cultivation has led to exploration of offshore environments as a viable alternative. The nature of many offshore environments often exposes seaweed farming systems to harsh environmental conditions, including strong waves, currents, and wind. These factors can lead to structural failures, kelp losses, and significant financial losses for seaweed farmers. The main objective of this study is to present a robust design and numerical analysis of an economically viable floating offshore kelp farm facility, and evaluate its stability and mooring system performance. A numerical method of preliminary designs of the offshore aquaculture systems were developed using the OrcaFlex software. The models were subjected to a series of dynamic environmental loading scenarios representing extreme events. These simulations aimed to forecast the overall dynamic response of an offshore kelp farm at a depth of 50m and to determine the best possible farm design with structural integrity for a selected offshore environment. Furthermore, to assess the economic feasibility of establishing offshore seaweed farms, a comprehensive capital expenses analysis was conducted. The results revealed that, in terms of the kelp farms with the same number of the kelp cultivating lines, the cost of building kelp farms will be strongly affected by the cost of mooring lines. The present study may help to understand the dynamic response and economic feasibility of offshore kelp farms.

Background: SARS-CoV-2, the coronavirus strain responsible for the COVID-19 pandemic, can lead to respiratory diseases ranging in severity. In the early stages, each U.S. state implemented a transition or “phasing” policy that included varying degrees of safety protocols. This allowed the states to slowly reopen while controlling transmission. The initial lockdown was observed to help suppress the pandemic, and our study aimed to determine if there was a correlation between fatality rates and the phase transitions across the states. Methods: Six states from regions with different caseloads were chosen for this study: Florida, California, New York, Washington, Kansas, and Texas. Incidence and mortality rate of COVID-19 were obtained from their respective government websites, allowing case fatality rates to be calculated and compared using Bayesian logistic mixed models. Results: When examining the fatality rates across phases grouped by state, there was a downward trend with each transition except in Texas. However, when the states were combined the overall downward trend was clear, with a median fatality rate of 0.039 in phase 0 dropping to 0.010 by phase 4. Conclusion: Implemented safety protocols and phase transitions were shown to assist in controlling the spread of COVID-19 as the states re-opened. Differences in fatality rates throughout the U.S. can likely be explained by how disciplined each state was with quarantine requirements and social distancing policies. This allowed certain states to control the infectious spread more efficiently than others, thus allowing the states to progress through the phase transitions at different rates.

The influence of mooring systems with lines of different material on the dynamic response of a floating wind turbine is studied using a 5 MW OC4-DeepCwind semi-submersible wind turbine as a representative prototype in this study. Two types of mooring systems were designed using the MoorDyn module in OpenFAST software (v3.1.0): one uses chains, and the other uses a hybrid mooring line composed of chains and high-strength polyethylene (HMPE) ropes. A wind turbine with two types of mooring systems was simulated using the OpenFAST software. The results show that the floating wind turbine moored with the hybrid lines exhibited a larger heave and pitch motion than that moored using chains alone. At the same time, the surge displacement was smaller than that of the wind turbine using chains alone. In terms of mooring line tension, the mean and amplitude values of the hybrid mooring system at the location examined were smaller than those of the chain mooring system. Thus, using HMPE ropes in the mooring system can significantly reduce line loads. In addition, the HMPE ropes used in the floating wind turbine mooring system did not affect the power generation of the wind turbine. This study provides promising support data and observations for applying high-strength polyethylene (HMPE) ropes in mooring systems for floating wind turbines.

Background SARS-CoV-2, the coronavirus strain responsible for the COVID-19 pandemic, can lead to severe respiratory disease and death. Worldwide, government officials tried to protect its citizens by mandating various lockdowns and social distancing policies to curb the spread. In the United States, each state initially implemented a transition or “phasing” policy that included varying degrees of safety protocols. This allowed them to re-open gradually, the goal being to reduce transmission rates while simultaneously allowing for higher degrees of public gatherings and events. The initial lockdown was observed to help suppress the pandemic, and the states–with guidance from the CDC–were left to their own agenda on how to best re-open their economy. This strategy was seen as optimal during the early stages of the pandemic. Our study aimed to determine if there was a correlation between fatality rates and phase transitions across the states. Methods The states selected for this study allowed for evaluation of different management styles throughout the phase transitions. COVID-19 case rates varied across the U.S.; some states observed higher infection rates than others. Thus, six states, each from regions with different caseloads and safety protocol compliance, were selected for this study: Florida, California, New York, Washington, Kansas, and Texas. Metrics such as incidence and mortality rate of COVID-19 infection were obtained from their respective government websites, allowing fatality rates to be calculated and compared using Bayesian logistic mixed models. Results There are significant outcomes when analyzing the data individually and as part of a meta-analysis. When examining the fatality rates across phases grouped by individual state, there was a downward trend with each transition except in Texas. New York was found to have the lowest median fatality rate (median [IQR]; 0.011 [0.007, 0.017]), followed by Washington (0.014 [0.011, 0.020]), Kansas (0.014 [0.009, 0.021], Texas (0.018 [0.013, 0.028]), California (0.021 [0.011, 0.037]), and Florida (0.022 [0.011, 0.034]). However, when the states’ data was pooled an overall downward trend was demonstrated, with a median fatality rate of 0.039 [0.019, 0.067] in phase 0, dropping to 0.010 [0.007, 0.013] by phase 4. A decrease in fatality rate odds by about 33.4% through each phase transition was observed when combining all the states. Conclusion Based on our results, implemented safety protocols and phase transitions were shown to assist in controlling the spread of COVID-19 as the states re-opened during the first year of the pandemic. Differences in fatality rates throughout the U.S. can likely be explained by how disciplined each state was with quarantine requirements and social distancing policies. This allowed certain states to control the infectious spread more efficiently than others, thus allowing them to progress through the phase transitions at different rates as they returned to normal. Future studies are warranted and can incorporate additional states for a more robust sample size. Further accounting for confounding variables, such as patient comorbidities and the introduction of COVID-19 vaccines at the end of 2020, would also allow insight into how fatality rates have been affected across the U.S.

Monkeypox (MPX) is a viral zoonosis with lesions like smallpox. Though rare in Nigeria, sporadic outbreaks have been reported in 17 states since September 2017. Unfortunately, the COVID-19 pandemic has further reduced surveillance and reporting of MPX disease. This study seeks to assess the effect of an enhanced surveillance approach to detect MPX cases and measure the cumulative incidence of MPX in priority states in Nigeria. We identified three priority states (Rivers, Delta and Bayelsa) and their Local Government Areas (LGAs) based on previous disease incidence. We also identified, trained, and incentivized community volunteers to conduct active case searches over three months (January to March 2021). We supported case investigation of suspected cases and followed up on cases in addition to routine active surveillance for MPX in health facilities and communities. Weekly and monthly follow-up was carried out during the same period. Out of the three states, 30 hotspots LGAs out of the 56 LGAs (54%) were engaged for enhanced surveillance. We trained three state supervisors, 30 LGA surveillance facilitators and 600 Community informants across the three priority states. Overall, twenty-five (25) suspected cases of MPX were identified. Out of these, three (12%) were confirmed as positive. Enhanced surveillance improved reporting of MPX diseases in hotspots LGAs across the priority states. Extension of this surveillance approach alongside tailored technical support is critical intra and post-pandemic.

Methods for carbon sequestration are warranted to tackle climate change caused by greenhouse gases released from anthropogenic activities. Seaweed is a type of marine plant that utilizes carbon dioxide for photosynthesis and has a substantial capacity to sequestrate carbon. Despite the huge potential, the long-lasting carbon sequestration (LLCS) of seaweed has never been calculated throughout its whole life cycle (nursery, temporary rearing, maturation, harvesting, and processing). In this paper, we use a life cycle assessment (LCA) approach to calculate the LLCS of seaweed, which can be understood as the difference between carbon fixation and released carbon throughout the life cycle of seaweed. Using kelp ( Laminaria japonica ) as an example of seaweed, the present study validates the procedure of calculating the LLCS of seaweed throughout its whole life cycle in Ailian Bay from nursery to processing into biochar (fertilizer) as the final product. The results showed that the carbon sequestration (full life cycle) of kelp in Ailian Bay was 97.73 g C m ^−2 year. Biomass carbon accounts for approximately 86% of the total value (982.53 g C m ^−2 year) of carbon absorption source of kelp in Ailian Bay, with the remaining 14% consisting of recalcitrant dissolved organic carbon and sedimentary carbon. Moreover, we calculated the amount of biomass carbon that was sequestrated by seaweed production in China from 2010 to 2020. Thus, the present study demonstrates that the mass production of seaweed can be utilized as an efficient method to sequestrate carbon and a feasible method for evaluating the effect of kelp farms on climate change.

Shepherd's model is considered as an improved and simple to-apply battery dynamic model. The experimental nominal parameters of five different capacities of Lithium-ion Polymer battery samples are established from the manufacturer's datasheets. The discharge and charge dynamics of the battery sample with the highest capacity, 3100 mAh are examined and validated. The clarity to derive the dynamic model parameters from the battery datasheet is a fascinating attribute of this model. The experimental database is utilized to study its dynamic feature and subsequently the dynamic battery model, which describes the relationship between the state of charge, the open circuit voltage and ambient temperature. The model is implemented and simulated by using MATLAB/Simulink tools. The current charge-discharge equations describe the optimized electrochemical activities with sustainable long cycle duration. The temperature model brings under control the aging effect, which plays down on the energy capacity of the battery. A steady load of 5 A is linked to the battery and used in a detail simulation of a direct current machine in determination of load effect. The compatibility of these equations and simulations implies that Shepherd's model is promising to provide guidelines for the analysis of discharge and charge in rechargeable polymer based lithium-ion batteries. The results show that the model can precisely illustrate the dynamic behavior of the batteries. [ABSTRACT FROM AUTHOR]

High-performance electrical insulation material can be manufactured using biomass plastic composite (BPC), which is a new type of composite material that is either made up of one or a combination of natural plant fibers/particulates, such as bamboo, cellulose fiber, rice husks, or hemp, and thermoplastic granules. In this study, the BPC composite material that was developed comprised polyethylene (PE), rice husk, and oyster shell. The results of the study showed a significant optimal improvement in the morphological, thermodynamic, and mechanical properties during the addition of 20% to 30% biomass particulates (i.e., rice husk and oyster shell). The thermogravimetric analysis, storage modulus, loss modulus, and damping factor (also known as the tangent of delta [tand]) values showed that compositions of the BPC material exhibited an increasing optimal thermomechanical stability when the composition of the BPC material was made with an increasing mixture of oyster shell, rice husk, and PE compared with that when only rice husk was added to PE. Similarly, the mechanical property of BPC was enhanced with 30% biomass material (i.e., rice husk and oyster shell) and 70% low-density PE plastics. This result indicated that BPC materials can be highly durable and long-lasting, as they are less prone to cracking or breaking. [ABSTRACT FROM AUTHOR]

An approach to develop a spaceframe vehicle structure that shows improved structural crashworthiness in frontal impacts is presented in this paper. A baseline model of the vehicle impact system was formulated through preconception of the vehicle size, shape, components' dimension and material. Preliminary evaluation of crash performance of the vehicle structure using the baseline model revealed some avenues to improve on crashworthiness. Wall thicknesses of the crash boxes, the lower fore rails, and the upper fore rails, were identified as design variables. Structural crashworthiness was evaluated at the design steps using appropriate metrics including; global absorbable energy index (GAEI), local absorbable energy index (LAEI) and acceleration severity index (ASI). A multi-objective optimisation problem was solved to maximise LAEI while ASI was minimised subject to the physical constraints of the system. Pareto optimal solutions showing 30–35% improvement on ASI were achieved with a reasonable 3.56–7.14% trade-off on the LAEI. [ABSTRACT FROM AUTHOR]

This study evaluated a multi-catenary spread mooring system design of a mobile ocean test berth for wave energy converters (WECs), the Ocean Sentinel (OS) instrumentation buoy, through dynamic simulation, numerical analysis, and comparison with measured field motion data of the OS off the OR coast. First, the accuracy of the numerical employed model based on a fully-coupled method of the OS and its mooring lines was validated by comparing predicted mooring tensions to the field measurements. Then, the anchor movability, fatigue damage, and extreme mooring tension of the OS mooring system were analyzed to assess survivability. Field test results show that the numerical model provided accurate predictions of mooring tensions even under environmental conditions of strong wind, current, and waves. Factors affecting the accuracy are discussed. One mooring anchor was shown to have moved significantly during the ocean field test. Mooring fatigue damage was calculated for different levels of sea states. Design strengths of the mooring lines were calculated and analyzed. [ABSTRACT FROM AUTHOR]

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