A comprehensive review on design, monitoring, and failure in fixed offshore platforms

Offshore platforms have had diverse applications in the marine industry, for example, oil or gas platforms can provide facilities to store the oil and gas before transport those to refineries. Offshore wind turbines are another well-known use of the offshore platform for generating power. As platforms encounter various strong forces from water and wind currents, the materials used for these structures are mainly steel or concrete. These platforms are classified into different types, according to the depth of water and their applications. In addition, offshore platforms, as artificial reefs may be used for decades at different marine conditions. Consequently, their design and maintenance are very important, otherwise, they can cause irreparable damage to the environment. This paper presents the latest and most significant design and monitoring methods, such as the optimal probabilistic seismic demand model, multi-objective optimization, dynamic response assessment, robust fault-tolerant control, etc., under different environmental and geographical conditions. Moreover, the effective factors on the life and failure of these offshore structures are comprehensively introduced to enhance awareness of them, which can be very helpful to improve the design and construction of more reliable and durable structures. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

Design of thermosensitive polymer‐coated magnetic mesoporous silica nanocomposites with a core‐shell‐shell structure as a magnetic/temperature dual‐responsive drug delivery vehicle

A stimuli-responsive nanocomposite with a core-shell-shell structure consisting of iron oxide (Fe3O4) nanoparticles as core, mesoporous silica as middle shell, and poly(N-isopropyl acrylamide-co-acrylic acid) (P[NIPAAm-co-AAc]) as an exterior shell with thermo-responsivity properties was synthesized to be used as a magnetic/temperature responsive drug delivery system. The structure, morphology, and size of P(NIPAAm-co-AAc)-coated mesoporous silica embedded magnetite nanoparticles (P(NIPAAm-co-AAc)@mSiO2@Fe3O4) were characterized by XRD, FTIR, and TEM analyses. Also, the heating ability of mesoporous silica-coated Fe3O4 nanoparticles, and P(NIPAAm-co-AAc)@mSiO2@Fe3O4 nanocomposites was investigated under the exposure of an alternating magnetic field (AMF). The results indicated that the prepared nanocomposites could generate enough heat for hyperthermia applications. Moreover, the magnetic/temperature-responsive drug release behavior of P(NIPAAm-co-AAc)@mSiO2@Fe3O4 nanocomposites loaded with fluorouracil (5-FU) was studied under the exposure of the AMF (frequency = 120 kHz, and amplitude = 22 kA m−1), as well as two different temperatures (37°C and 45°C). The results showed that only 7.8% of the drug could be released after 20 h at 37°C (below the LCST of the copolymer). In contrast, by increasing the temperature of release medium up to 45°C (above the LCST of the copolymer), the amount of released drug was increased up to 47%. Moreover, by exposing the prepared nanocomposite to a safe AMF, a burst release of drug was observed, indicating the excellent responsivity of the carrier to an external magnetic field. These results proved that the obtained nanocomposite has a great performance to be used as a magnetic/temperature-sensitive drug carrier for advanced drug delivery applications