4D Printing of Shape Memory Materials for Textiles: Mechanism,Mathematical Modeling,and Challenges

Shape memory materials (SMMs) in 3D printing (3DP) technology garnered much attention due to their ability to respond to external stimuli, which direct this technology toward an emerging area of research, “4D printing (4DP) technology.” In contrast to classical 3D printed objects, the fourth dimension, time, allows printed objects to undergo significant changes in shape, size, or color when subjected to external stimuli. Highly precise and calibrated 4D materials, which can perform together to achieve robust 4D objects, are in great demand in various fields such as military applications, space suits, robotic systems, apparel, healthcare, sports, etc. This review, for the first time, to the best of the authors’ knowledge, focuses on recent advances in SMMs (e.g., polymers, metals, etc.) based wearable smart textiles and fashion goods. This review integrates the basic overview of 3DP technology, fabrication methods, the transition of 3DP to 4DP, the chemistry behind the fundamental working principles of 4D printed objects, materials selection for smart textiles and fashion goods. The central part summarizes the effect of major external stimuli on 4D textile materials followed by the major applications. Lastly, prospects and challenges are discussed, so that future researchers can continue the progress of this technology.     

Middleware Technologies for Smart Wireless Sensor Networks towards Internet of Things: A Comparative Review

Wireless Personal Communications - Internet of Things (IoT) offers complex networks of connected devices, which are used to serve in the real-time environment. Interestingly, Wireless Sensor...     

Secure and Privacy-Preserving RFID Authentication Scheme for Internet of Things Applications

Wireless Personal Communications - Privacy issue has become a crucial concern in internet of things (IoT) applications ranging from home appliances to vehicular networks. RFID system has found...     

Turmeric nanofiber-encapsulated natural product formulation act as a phytogenic feed additive—A study in broilers on growth performance,biochemical indices of blood,and E. coli in cecum

A phytogenic feed additive (PFA) formulation was prepared with bioactive molecules—curcuminoids, gingerol, and carvacrol by encapsulating in nanofiber isolated from turmeric spent (turmeric nanofiber, TNF). This formulation was completely characterized by scanning electron microscope, ultra performance liquid chromatography, and gas chromatography and evaluated for its efficacy. PFA-encapsulated TNF (PFA@TNF) considerably increased mean body weight, decreased cholesterol level, mortality rate, and reduced Escherichia coli content of broilers than antibiotic growth promoter (AGP). The depth of crypts in the ileum of broilers was considerably reduced by the inclusion of PFA@TNF in diets compared with the AGP.     

A combined theoretical and experimental investigation of the valorization of mechanical and thermal properties of the fly ash-reinforced polypropylene hybrid composites

Journal of Materials Science - Fly ash (FA) particles were surface modified with cetyltrimethylammonium bromide (Ctab) and hybridized with graphene oxide (GO) and carboxymethyl cellulose (CMC)...     

Assessment of Post-Earthquake Fire Behavior of a Steel MRF Building in a Low Seismic Region

International Journal of Steel Structures - Building-level response to post-earthquake fire hazards in steel buildings has been assessed using primarily two-dimensional analyses of the lateral...     

Fabrication and characterization of poly(methyl methacrylate)/CaCu3Ti4O12 composites

Composites comprising Poly(Methyl Methacrylate) (PMMA) and CaCu₃Ti₄O₁₂ (CCTO) via melt mixing followed by hot pressing were fabricated. These were characterized using X‐ray diffraction, thermo gravimetric, scanning electron microscopy, and Impedance analyzer for their structural, morphology, and dielectric properties. Composites were found to have better thermal stability than that of pure PMMA. The composite, with 38 Vol % of CCTO (in PMMA), exhibited remarkably low dielectric loss at high frequencies and the low frequency relaxation is attributed to the space charge polarization/MWS effect. Theoretical models were employed to rationalize the dielectric behavior of these composites. At higher temperatures, the relaxation peak shifts to higher frequencies, due to the merging of both β and α relaxations into a single dielectric dispersion peak. The AC conductivity in the high frequency region was attributed to the electronic polarization. POLYM. ENG. SCI., 54:551–558, 2014. © 2013 Society of Plastics Engineers     

Characterization of microstructures and oxidation behaviour of Nb–20Si–20Cr–5Al alloy

Static oxidation in air was performed on Nb–20Cr–20Si–5Al alloy at high temperatures ranging from 700 to 1400 °C. Pesting occurred at 700 °C while internal oxidation took place at 1300 and 1400 °C where Al₂O₃ initiated at the interface between NbCr₂ and Nb₉Cr₃Si₂ phases. Phases present were Nb₅Si₃, NbCr₂, Nb solid solution and Nb₉Cr₃Si₂ depending on the temperature. The aluminium content on each of the phases was analyzed. Al content in Nb₉Si₂Cr₃ has been found to be as high as 5–6 atomic percent. SEM, EDS and XRD techniques were utilized in order to characterize the specimens.     

Enhanced magnetization and magnetoelectric coupling in hydrogen treated hexagonal YMnO3

The single phase hexagonal YMnO₃ has been synthesized via sol-gel route by adopting two different sintering conditions. In one case, sintering has been done at ∼700 °C in Ar/H₂ atmosphere and in other case it has been done at ∼1250 °C in air. Magnetic measurements of the samples, synthesized by sintering at relatively lower temperature in Ar/H₂ atmosphere, show the enhanced ferromagnetic behaviour at 10 K. M-H curve shows that the value of saturation magnetization (M_s) at 10 K is 8.04 emu/g for Ar/H₂ sintered sample while it is 2.93 emu/g for the air sintered sample. Moreover, a weak ferromagnetic signal at room temperature has been observed in YMnO₃ compound. Magnetization versus magnetic field (M-H) curves of hydrogen treated samples, measured at room temperature, show small kink in the linear variation near origin, possibly due to presence of weak ferromagnetic interactions in the samples at room temperature. However, the polarization-electric field (P-E) curve shows weak ferroelectric characteristics for the Ar/H₂ sintered samples. It is suggested that the enhanced ferromagnetism in Ar/H₂ sintered sample originates from the presence of oxygen vacancies in the Ar/H₂ sintered samples. Moreover, the magnetoelectric coupling coefficient at room temperature is improved to 106 mV/cm Oe for Ar/H₂ sintered sample as compared to 96 mV/cm Oe for air sintered sample at 40 kHz ac magnetic field frequency.