Fabrication and Characterization of Nanostructured AACVD Thin Films on 316L SS as Surface Protective Layers in Simulated Body Fluid

Metallurgical and Materials Transactions A - The surface of implant materials is one of the most significant factors for controlling the interaction between biomaterials and bone tissues. Hence,...     

Rapid Biofabrication of Printable Dense Collagen Bioinks of Tunable Properties

Recent convergence of the 3D printing of tissue‐like bioinks and regenerative medicine offers promise in the high‐throughput engineering of in vitro tissue models and organoids for drug screening and discovery research, and of potentially implantable neo‐tissues with tailored structural, biological, and mechanical properties. However, the current printing approaches are not compatible with collagen, the native scaffolding material. Herein, a unique biofabrication approach that uses automated gel aspiration‐ejection (GAE) is reported to potentially overcome these challenges. Automated‐GAE generates highly defined, aligned, dense collagen gel bioinks of various geometries (i.e., cylindrical, quadrangular, and tubular), dimensions, as well as tunable microstructural and mechanical properties that modulate seeded cellular responses. By densifying initial naturally derived reconstituted collagen hydrogels incorporating cells, automated‐GAE generates mini‐tissue building blocks with tailored protein fibril density and alignment, as well as cell loading, density and orientation according to the intended use. Surprisingly, a simple mathematical relationship defining the bioink compaction factor is found to be highly effective in predicting the initial and temporal properties of the bioinks in culture. Therefore, automated‐GAE will potentially also enable a fourth dimension to biofabrication, where cell–cell communications and cell‐extracellular matrix interactions as a function of time in culture can be predicted and modeled.     

Hydrogen from solar energy,a clean energy carrier from a sustainable source of energy

Solar energy is going to play a crucial role in the future energy scenario of the world that conducts interests to solar-to-hydrogen as a means of achieving a clean energy carrier. Hydrogen is a sustainable energy carrier, capable of substituting fossil fuels and decreasing carbon dioxide (CO₂) emission to save the world from global warming. Hydrogen production from ubiquitous sustainable solar energy and an abundantly available water is an environmentally friendly solution for globally increasing energy demands and ensures long-term energy security. Among various solar hydrogen production routes, this study concentrates on solar thermolysis, solar thermal hydrogen via electrolysis, thermochemical water splitting, fossil fuels decarbonization, and photovoltaic-based hydrogen production with special focus on the concentrated photovoltaic (CPV) system. Energy management and thermodynamic analysis of CPV-based hydrogen production as the near-term sustainable option are developed. The capability of three electrolysis systems including alkaline water electrolysis (AWE), polymer electrolyte membrane electrolysis, and solid oxide electrolysis for coupling to solar systems for H₂ production is discussed. Since the cost of solar hydrogen has a very large range because of the various employed technologies, the challenges, pros and cons of the different methods, and the commercialization processes are also noticed. Among three electrolysis technologies considered for postulated solar hydrogen economy, AWE is found the most mature to integrate with the CPV system. Although substantial progresses have been made in solar hydrogen production technologies, the review indicates that these systems require further maturation to emulate the produced grid-based hydrogen.     

A zero-current switching switched-capacitor DC-DC converter with reduction in cost,complexity, and size

This paper presents a new step-up switched-capacitor (SC) DC-DC converter which has many advantages such as reduction in investment cost, control complexity, number of components, voltage stress on components, and size over traditional topologies. In the proposed structure, power switches are reduced in number which in turn leads to the merits mentioned earlier and makes the converter more suitable for industrial applications. Furthermore, a previously introduced zero-current switching (ZCS) method is used here which provides soft switching for the devices. There is also a reduction in the number of required inductors to achieve ZCS due to the decreased number of switches in the proposed converter. The proposed converter is validated by comprehensive simulation results in MATLAB Simulink environment and also precise experimental results which show the acceptable performance of the proposed topology.     

Metal‐Based Nanomaterials in Biomedical Applications: Antimicrobial Activity and Cytotoxicity Aspects

Microbial colonization on material surfaces is ubiquitous. Biofilms derived from surface‐colonized microbes pose serious problems to the society from both an economical perspective and a health concern. Incorporation of antimicrobial nanocompounds within or on the surface of materials, or by coatings, to prevent microbial adhesion or kill the microorganisms after their attachment to biofilms, represents an important strategy in an increasingly challenging field. Over the last decade, many studies have been devoted to preparing meta‐based nanomaterials that possess antibacterial, antiviral, and antifungal activities to combat pathogen‐related diseases. Herein, an overview on the state‐of‐the‐art antimicrobial nanosized metal‐based compounds is provided, including metal and metal oxide nanoparticles as well as transition metal nanosheets. The antimicrobial mechanism of these nanostructures and their biomedical applications such as catheters, implants, medical delivery systems, tissue engineering, and dentistry are discussed. Their properties as well as potential caveats such as cytotoxicity, diminishing efficacy, and induction of antimicrobial resistance of materials incorporating these nanostructures are reviewed to provide a backdrop for future research.     

A machine learning approach to detect changes in gait parameters following a fatiguing occupational task

The purpose of this study is to provide a method for classifying non-fatigued vs. fatigued states following manual material handling. A method of template matching pattern recognition for feature extraction ($1 Recognizer) along with the support vector machine model for classification were applied on the kinematics of gait cycles segmented by our stepwise search-based segmentation algorithm. A single inertial measurement unit on the ankle was used, providing a minimally intrusive and inexpensive tool for monitoring. The classifier distinguished between states using distance-based scores from the recogniser and the step duration. The results of fatigue detection showed an accuracy of 90% across data from 20 recruited subjects. This method utilises the minimum amount of data and features from only one low-cost sensor to reliably classify the state of fatigue induced by a realistic manufacturing task using a simple machine learning algorithm that can be extended to real-time fatigue monitoring as a future technology to be employed in the manufacturing facilities.

Practitioner Summary: We examined the use of a wearable sensor for the detection of fatigue-related changes in gait based on a simulated manual material handling task. Classification based on foot acceleration and position trajectories resulted in 90% accuracy. This method provides a practical framework for predicting realistic levels of fatigue.     

A new method to determine the synergistic effects of area ratio and microstructure on the galvanic corrosion of LAS A508/309 L/308 L SS dissimilar metals weld

The synergistic effects of area ratio and microstructure on the galvanic corrosion of A508/309 L/308 L dissimilar metals weld(DMW)are studied by a multi-analytical approach.It was demonstrated that decreasing the anode/cathode surface area ratio obviously enhances the corrosion rate of A508,both locally and globally.Deeper analyses of the AFM results enabled quantitative comparison of the corrosion behaviour of the different surface constituents.It was revealed that in the galvanic interaction of the DMW,the grain refined region corrodes most,followed by the partial grain refined region and base metal matrix of the A508,respectively.The electrochemical localization index(LI)estimation method and AFM analysis both confirmed the presence of a mixed(localized and uniform)corrosion phenomenon occurring on the surface of the A508 anode metal in the galvanic interaction of the dissimilar metals.Finally,the degree of synergism equation was utilized to describe the synergistic effects of anode/cathode area ratio and the microstructure of the samples on the galvanic corrosion of LAS A508/309L/308L SS DMW.     

Adsorption of BSA onto hexagonal mesoporous silicate loaded by APTES and tannin: Isotherm,thermodynamic and kinetic studies

In the present study, hexagonal mesoporous silica (HMS) was synthesized and modified by tannic acid as a natural poly-phenol and amine (TA-A-HMS) and was applied for the adsorption of bovine serum albumin (BSA) from aqueous media. To investigate the structure of HMS and TA-A-HMS, SEM, TEM, XRD, BET and FTIR analysis were applied. The effects of pH, adsorbent dosage, contact time and temperature on the BSA adsorption were studied. After modification, BET surface area of HMS was reduced from 885?m²/g to 51?m²/g which confirms the presence of tannin and amine groups that inhibit the adsorption of nitrogen molecules. According to the results of equilibrium data, it is shown that Langmuir isotherm with maximum adsorption capacity of 1000?mg/g is the predominant model and adsorption is mono-layer. Kinetic and thermodynamic studies also reveal that adsorption kinetic followed by pseudo-second order model and the adsorption process is exothermic.     

Advanced constitutive modelling for creep-fatigue assessment of high temperature components

Creep-fatigue assessment procedures for the design of high-temperature components should ensure lifetime predictions which are safe but not excessively conservative. Adoption of more accurate assessment procedures than are presently available enable the availability of power plant with greater operating flexibility. Operating flexibility is becoming a key market driver due to the increased interest in the use of intermittent renewable energy sources (e.g. wind, solar) which place focus on a requirement for turbo-machinery to be capable of reduced start-up and shut-down times. This study introduces a creep-fatigue assessment procedure for the design of high-temperature components required for flexible operation. In particular, it considers alloys with high creep-fatigue deformation/damage interaction characteristics such as the advanced martensitic 9–11%Cr steels which are widely used for power plant applications. The procedure takes advantages of advanced constitutive models and implements them in a state-of-the-art mechanical assessment procedure for calculating high-temperature component life times.     

Engineering Cell Surface Function with DNA Origami

A specific and reversible method is reported to engineer cell‐membrane function by embedding DNA‐origami nanodevices onto the cell surface. Robust membrane functionalization across epithelial, mesenchymal, and nonadherent immune cells is achieved with DNA nanoplatforms that enable functions including the construction of higher‐order DNA assemblies at the cell surface and programed cell–cell adhesion between homotypic and heterotypic cells via sequence‐specific DNA hybridization. It is anticipated that integration of DNA‐origami nanodevices can transform the cell membrane into an engineered material that can mimic, manipulate, and measure biophysical and biochemical function within the plasma membrane of living cells.