Wave propagation simulation in an electrically open shell reinforced with multi-phase nanocomposites

Wave propagation simulation in a multi-hybrid nanocomposite (MHC)-reinforced doubly curved open shell covered with piezoelectric actuator is examined for the first time. The third-order shear deformation theory (third-order SDT) is applied to formulate the stress–strain relations. Rule of the mixture and modified Halpin–Tsai model are engaged to provide the effective material constants of the MHC-reinforced open shell. By employing Hamilton’s principle, the governing equations of the structure are derived. Via the compatibility rule, the bonding between the smart layer and sandwich open shell is modeled. Also, with the aid of Maxwell's equation, the mechanics of the piezoelectric layer are formulated. Afterward, a parametric study is carried out to investigate the effects of the CNTs’ weight fraction, various FG face sheet patterns, small radius to total thickness ratio, the thickness of the smart layer, externally applied voltage, and carbon fiber angle on the phase velocity of the MHC-reinforced open shell. Another necessary consequence is that as the externally applied voltage to the piezoelectric layer of the smart open shell increases, there will be seen an enhancement on the phase velocity or wave response of the system and without a doubt this issue is much more substantial at the lower wave number. It is also observed that when the applied voltage is more than zero, we can find a range for the fiber angle that these values are the critical fiber angle and this critical range will expand by increasing the external electrical load. The useful suggestion of this study is that for designing the structure, we should attention to the FG pattern and higher value of the wavenumber, simultaneously. The presented study outputs can be used in ultrasonic inspection techniques and structural health monitoring.

     

Transformation Mechanism of Preprecipitation NiMn Nanostructures

The transformation mechanism of constrained b.c.c NiMn (β phase) clusters coherently precipitated during isothermal aging of Fe-Ni-Mn maraging alloy at 753 K (480 °C) has been studied. Preprecipitation of β-NiMn phase was demonstrated using conventional and high-resolution transmission electron microscopy and confirmed by flanking of electron diffraction spots, X-ray diffraction sidebands, and the invariance of lattice parameter and peak breadths in the earlier stages of age hardening. The β-NiMn clusters were recognized with interfacial dislocation dipoles lying on {011} _α planes and Burgers vectors of a ₀ $ \left\langle {01\overline{1} } \right\rangle_{\alpha } $ type. During further aging, the β-NiMn clusters transformed martensitically into fct NiMn (θ phase) precipitates as envisaged by the characteristic microtwinning texture. Considering the anomalous elastic softness of β-NiMn alloy, the transformation was plausibly assumed to take place by the localized soft-mode mechanism in which the structural instability of clusters is stimulated by the strain field of the interfacial dislocations. Computerized calculations in accordance with the phenomenological theory of martensite crystallography indicated that microtwinning of martensitic θ precipitates occurs in a self-accommodating manner. Transformation of very small β clusters at earlier stages of aging is thermodynamically hampered by the interfacial energy barrier.     

Lead hexa-ferrites and magnetic cellulose acetate nanocomposites: study of magnetization,coercivity and remanence

Hard magnetic PbFe₁₂O₁₉ nanostructures were synthesized via a simple and rapid microwave method. The effect of concentration, temperature and power on the morphology was investigated. The products were characterized by X-ray diffraction, scanning electron microscopy, and Fourier transform infrared spectroscopy. Alternating gradient force magnetometer shows ferromagnetic property of the hexa-ferrite nanostructures. In order to prepare polymeric nanocomposite, lead ferrite nanoparticles were added to cellulose acetate polymer. The results show that saturation magnetization of nanocomposite was decreased while coercivity was increased (due to dispersion of particles into polymeric matrix).     

Railroad capacity tools and methodologies in the U.S. and Europe

A growing demand for passenger and freight transportation, combined with limited capital to expand the United States (U.S.) rail infrastructure, is creating pressure for a more efficient use of the current line capacity. This is further exacerbated by the fact that most passenger rail services operate on corridors that are shared with freight traffic. A capacity analysis is one alternative to address the situation and there are various approaches, tools, and methodologies available for application. As the U.S. continues to develop higher speed passenger services with similar characteristics to those in European shared-use lines, understanding the common methods and tools used on both continents grows in relevance. There has not as yet been a detailed investigation as to how each continent approaches capacity analysis, and whether any benefits could be gained from cross-pollination. This paper utilizes more than 50 past capacity studies from the U.S. and Europe to describe the different railroad capacity definitions and approaches, and then categorizes them, based on each approach. The capacity methods are commonly divided into analytical and simulation methods, but this paper also introduces a third, “combined simulation–analytical” category. The paper concludes that European rail studies are more unified in terms of capacity, concepts, and techniques, while the U.S. studies represent a greater variation in methods, tools, and objectives. The majority of studies on both continents use either simulation or a combined simulation–analytical approach. However, due to the significant differences between operating philosophy and network characteristics of these two rail systems, European studies tend to use timetable-based simulation tools as opposed to the non-timetable-based tools commonly used in the U.S. rail networks. It was also found that validation of studies against actual operations was not typically completed or was limited to comparisons with a base model.

     

Marine Bioactive Compounds and Their Health Benefits: A Review

The significance of marine creatures as a source of unique bioactive compounds is expanding. Marine organisms constitue nearly half of the wordwide biodiversity; thus, oceans and sea present a vast resource for new substances and it is considered the largest remaining reservoir of beneficial natural molecules that maight be used as functional constituents in the food sector. This review is an update to the information about recent functional seafood compounds (proteins, peptides, amino acids, fatty acids, sterols, polysaccharides, oligosaccharides, phenolic compounds, photosynthetic pigments, vitamins, and minerals) focusing on their potential use and health benefits.     

Development of dry powder inhaler formulation loaded with alendronate solid lipid nanoparticles: solid-state characterization and aerosol dispersion performance

Alendronate sodium is a bisphosphonate drug used for the treatment of osteoporosis and acts as a specific inhibitor of osteoclast-mediated bone resorption. Inhalable solid lipid nanoparticles (SLNs) of the alendronate were successfully designed and developed by spray-dried and co-spray dried inhalable mannitol from aqueous solution. Emulsification technique using a simple homogenization method was used for preparation of SLNs. In vitro deposition of the aerosolized drug was studied using a Next Generation Impactor at 60?L/min following the methodology described in the European and United States Pharmacopeias. The Carr’s Index, Hausner ratio and angle of repose were calculated as suitable criteria for estimation of the flow behavior of solids. Scanning electron microscopy showed spherical particle morphology of the respirable particles. The proposed spray-dried nanoparticulate-on-microparticles dry powders displayed good aerosol dispersion performance as dry powder inhalers with high values in emitted dose, fine particle fraction and mass median aerodynamic diameter. These results indicate that this novel inhalable spray-dried nanoparticulate-on-microparticles aerosol platform has great potential in systemic delivery of the drug.