Search

In this paper, a novel rubber nanocomposite containing phenyl-vinyl-methyl-polysiloxane (PVMQ) and ethylene propylene diene monomer (EPDM) was produced during a two-roll mill procedure for mechanical applications. For this purpose, ethylene propylene diene monomer-grafted-maleic anhydride compatibilizer (EPDM-g-MAC) and graphene oxide (GO) was used as a compatibilizer and reinforcements to make a uniform composite. To study mechanical and physical characterizations, dynamic mechanical thermal analysis (DMTA), rheology, morphology, and curing characterizations of nanocomposites were investigated, which showed that compatibilizer makes GO dispersion uniformly. An electrical resistivity test was performed to study the electrical conductivity of the nanocomposites. The results indicate that the samples with higher GO content had a response to the electrical current. The curing study indicates that, by increasing the GO nanoparticles in the presence of EPDM-g-MAC, the curing properties are enhanced as well as mechanical properties by improving the bonding among GO, compatibilizer, and matrix [tensile strength (54%), modulus (68%), elongation-at-break (67%), hardness (81%), and fatigue (51%)]. FE-SEM and TEM images demonstrated that, by increasing GO nanoparticles in the presence of compatibilizer, the mean diameter of EPDM decreased in the substrate, which consequently increased the mechanical properties. The changes in surface temperature were investigated with constant voltage (75 V), which indicates that by increasing GO nanoparticles and electrical conductivity, the surface temperature increased significantly. The results of practical experiments showed good agreement with the theoretical results. [ABSTRACT FROM AUTHOR]

Hyperglycemia, a distinguishing feature of diabetes mellitus that might cause a diabetic foot ulcer (DFU), is an endocrine disorder that affects an extremely high percentage of people. Having a comprehensive understanding of the molecular mechanisms underlying the pathophysiology of diabetic wound healing can help researchers and developers design effective therapeutic strategies to treat the wound healing process in diabetes patients. Using nanoscaffolds and nanotherapeutics with dimensions ranging from 1 to 100 nm represents a state‐of‐the‐art and viable therapeutic strategy for accelerating the wound healing process in diabetic patients, particularly those with DFU. Nanoparticles can interact with biological constituents and infiltrate wound sites owing to their reduced diameter and enhanced surface area. Furthermore, it is noteworthy that they promote the processes of vascularization, cellular proliferation, cell signaling, cell‐to‐cell interactions, and the formation of biomolecules that are essential for effective wound healing. Nanomaterials possess the ability to effectively transport and deliver various pharmacological agents, such as nucleic acids, growth factors, antioxidants, and antibiotics, to specific tissues, where they can be continuously released and affect the wound healing process in DFU. The present article elucidates the ongoing endeavors in the field of nanoparticle‐mediated therapies for the management of DFU. Significance statement: To sum up, this study emphasizes that it may be feasible to develop better treatments for improperly healed diabetic wounds by studying the molecular mechanics of diabetic wound healing. As new products, nanomaterials can transfer nucleic acids, growth factors, antioxidants, and antibiotics to specified tissues for continuous release. Moreover, nanomaterials are more likely to interact with biological systems and infiltrate wound sites due to their smaller diameter and larger surface area. Hence, nano‐scaffolds and nano‐therapeutics can accelerate diabetic wound healing. [ABSTRACT FROM AUTHOR]

Summary: This paper investigates design of an adaptive fixed‐time fault‐tolerant decentralized controller for a class of uncertain multi‐input multi‐output (MIMO) switched large‐scale non‐strict interconnected systems under arbitrary switching subject to unknown control directions, quantized nonlinear inputs, actuator failures unknown external disturbances, and unmodeled dynamics. In addition to interconnected terms, time‐varying delayed interconnected terms have been considered in the system model which makes it more general than previous works in the literature. The proposed controller can handle switched systems with unknown switching signal and different types of input nonlinearities including, saturation, backlash, and dead‐zone. The singularity problem in designing the fixed time controller has been solved. The quantizer and actuators fault parameters are assumed to be unknown. The Razumikhin lemma has been used to deal with the delayed interconnected terms. To cope with the system unknown dynamics, neural networks (NNs) have been applied and by updating the maximum norms of the networks weight vectors the computational load has been reduced. The explosion of complexity occurring in the traditional back‐stepping technique has been avoided by applying dynamic surface control (DSC). Finally, by defining an appropriate common Lyapunov function (CLF), fixed‐time convergence of system outputs and the closed‐loop system stability have been established. The effectiveness of the proposed controller has been shown via simulation study. [ABSTRACT FROM AUTHOR]

The development of novel antifungal agents and, in particular, the widespread use of these medications over the course of the past two decades, has had a significant impact on the treatment of fungal infectious diseases. This has resulted in a complete transformation of the treatment of fungal infectious diseases. However, the widespread development of antibiotic resistance has masked the significance of such breakthroughs. Antifungal infection treatment with nanoparticles has been shown to be effective. As a result of their unique characteristics, these substances, in contrast to antibiotics in their purest form, are able to exhibit an increased anti-proliferative capacity while requiring a lower concentration than traditional drugs do in order to achieve the same effect. Decreased drug effectiveness, minimal tissue penetration throughout tissue, restricted tissue penetration, decreased bioavailability, poor drug pharmacokinetics, and low water solubility are some of the major factors contributing to the employment of antifungal medicines in delivery systems. Because of this, one of the primary goals of incorporating antifungal medications into varying sorts of nanoparticles is to reduce the negative effects of the drugs' inherent qualities. This article provides an overview of the many types of nanoparticles, such as metal, metal oxide, and non-metal oxide nanoparticles, carbon-based nanoparticles, nanostructured lipid carriers, polymeric nanoparticles, solid lipid nanoparticles, nanofibers, antifungal peptides, composites, and ZnO quantum dots, that can be used as antifungal drug delivery systems, as well as the benefits that these nanomaterials have over purified medications. [ABSTRACT FROM AUTHOR]

In this work, simultaneous inferential control of particle size distribution (PSD) and molecular weight distribution (MWD) in a semi-batch emulsion polymerization reactor of styrene has been addressed. Using a comprehensive dynamic model for PSD and MWD predictions and performing a sensitivity analysis, it has been revealed that free surfactant and chain transfer agent (CTA) concentrations in the reactor are the most suitable candidates for inferential control of PSD and MWD, respectively. To control concentrations of these species in the reactor, their inlet feed flow rates are used as manipulated variables. It is assumed that the concentration of CTA is measured infrequently and therefore an open-looped observer, based on the reaction calorimetry, has been designed to estimate the CTA concentration. The infrequent measurements of CTA concentration are used to correct its estimation. As the online measuring of the ionic free surfactant concentration is also difficult, solution conductivity which is a good indication of free surfactant concentration is used for control purposes. Simulation results show that the performance of the proposed control scheme is satisfactory even in the presence of model mismatch. POLYM. ENG. SCI., 50:2306-2320, 2010. [C] 2010 Society of Plastics Engineers, INTRODUCTION Emulsion polymerization is one of the most important processes in polymer industries for producing a wide range of special products such as latex paints and coating, adhesive, synthetic rubber, [...]

Summary: In this paper, the design of an adaptive tracking control for a class of switched uncertain multiple‐input–multiple‐output nonlinear systems in the strict‐feedback form with unmodeled dynamics in the presence of three types of input nonlinearity under arbitrary switching has been addressed. By means of an intelligent approximator like a fuzzy logic system or a neural network, the unknown dynamics are estimated. The unmodeled dynamics have been tackled with a dynamic signal. A universal framework for describing different types of input nonlinearity including saturation, backlash, and dead zone has been utilized. By applying the backstepping approach and the common Lyapunov function method, virtual and actual controllers and the adaptive law for each subsystem have been constructed. Finally, it has been shown that the closed‐loop system is semiglobally uniformly ultimately bounded and the tracking errors converge to their predefined bounds. The effectiveness of the proposed control scheme has been shown through simulation study. [ABSTRACT FROM AUTHOR]

ABSTRACT In this study, the inverse emulsion polymerization modeling of polyacrylamide with population balance equations (PBEs) was performed. The PBEs were derived on the basis of the zero-one kinetic model. The effects of the surfactant steric barrier and surfactant reaction with radicals, including monomeric radicals, on the radical entry rate into the particle were taken into account. In the modified model, the coagulation phenomenon was included through consideration of the effects of forces not included in the Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory; these include hydration and steric forces in addition to DLVO forces. The effects of the surfactant and initiator concentrations on the conversion, particle size, and average molecular weight (MW) were investigated by simulation and experimental studies. Increasing the surfactant concentration initially increased the conversion and decreased MW. A further increase in the surfactant concentration resulted in a decrease in the conversion and an increase in MW. The average particle size decreased with an increase in the surfactant concentration. An increase in the initiator concentration led to an increase in the monomer conversion and a decrease in the average MW. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41916. [ABSTRACT FROM AUTHOR]

A deterministic model based on thediscrete population balanceequation (PBE) is used to examine the precipitation of barium sulfatenanoparticles in nonionic inverse microemulsion systems. It is shownthat coagulation can have a significant effect at low initial reactantsconcentration. The simulation results show that a bimodal particlesize distribution (PSD) observed in experimental analysis reportedin the literature cannot be predicted by neglecting the coagulationeffect. A coagulation kernel is proposed that takes into account theeffect of interparticle forces through the Fuchs’ stabilityratio. The effect of electrolyte concentration on the surfactant headgrouparea is also investigated. It is shown that at lower electrolyte concentration,the nucleation and growth rates increase because of higher interdropletexchange rate. The simulation results show a qualitatively good agreementwith experimental data regarding PSD prediction and dynamic evolutionof mean particle diameter. [ABSTRACT FROM AUTHOR]

In this work, the method of moments is used for solution of population balance equations appearing in modeling of emulsion polymerization (EP). The zero-one model without coagulation effect and the pseudo-bulk model including coagulation effect are investigated as two common approaches for modeling EP processes. The fixed quadrature method is used to close the set of moment equations, and the maximum entropy approach is applied to reconstruct the particle size distribution from a finite number of its moments. Comparing the results with those obtained by the high-precision finite volume technique indicates that, despite the low computational load of the moment method, it has an acceptable accuracy. These features support use of the moment technique for other applications such as on-line control or optimization in particulate processes. [ABSTRACT FROM PUBLISHER]

• By increasing PVA concentration, more HA induced and bioactivity increased and as a result osteoblast's performance enhanced. • The homogenously and uniformly coat was produced on PVA20 than PVA15 and PVA25. • PVA 20 caused lower agglomeration than PVA15 and PVA25. So, HA induced more uniformity on the surface. • Increasing PVA concentration improves the corrosion resistance on the stainless-steel implant. • Adhesion effect of PVA20 was more pronounced than PVA15 and PVA25. In this work, 316L stainless steel was coated by polyvinyl alcohol (PVA) reinforced natural chitosan (CH)/ bioactive glass (BG) composite coating, as an implant, by electrophoretic deposition (EPD) process. The properties of the composite coating were investigated with different PVA concentrations (15, 20 and 25 wt.%) in the composite suspension. These were characterized by X-ray diffraction (XRD), furrier infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). SEM micrograph confirmed the uniform coating. The corrosion resistance was studied in phosphate buffer saline (PBS) solution by polarization test. The increase corrosion resistance of 25 wt.% PVA of composite coating indicated more bio-stability of the composite coated in-vitro compared to 15 wt.% and 20 wt.% PVA composite coated. An in-vitro bioactivity test was performed in a PBS solution for 3, 7 and 14 days, respectively. The decomposition rate of coats shows that the composite coating with 20 wt.% PVA coating is proposed the best bioactivity and hydroxyapatite (HA) forming ability compared to 15 wt.% and 25 wt.% PVA coating. Likewise, adhesive test indicates more adhesively in the composite with 20 wt.% PVA composite than others. [ABSTRACT FROM AUTHOR]

As a result of the transformation of inflexible electronic structures into flexible and stretchy devices, wearable electronics now provide great advantages in a variety of fields, including mobile healthcare sensing and monitoring, human-machine interfaces, portable energy storage and harvesting, and more. Because of their enriched surface functionalities, large surface area, and high electrical conductivity, transition metal nitrides and carbides (also known as MXenes) have recently come to be extensively considered as a group of functioning two-dimensional nanomaterials as well as exceptional fundamental elements for forming flexible electronics devices. This Review discusses the most recent advancements that have been made in the field of MXene-enabled flexible electronics for wearable electronics. The emphasis is placed on extensively established nonstructural features in order to highlight some MXene-enabled electrical devices that were constructed on a nanometric scale. These attributes include devices configured in three dimensions: printed materials, bioinspired structures, and textile and planar substrates. In addition, sample applications in electromagnetic interference (EMI) shielding, energy, healthcare, and humanoid control of machinery illustrate the exceptional development of these nanodevices. The increasing potential of MXene nanoparticles as a new area in next-generation wearable electronic technologies is projected in this Review. The design challenges associated with these electronic devices are also discussed, and possible solutions are presented., Competing Interests: The authors declare no competing financial interest., (© 2023 The Authors. Published by American Chemical Society.)