Effect of graphene nanoplatelets presence on the morphology,structure, and thermal properties of polypropylene in fiber melt‐spinning process

Melt spinning of graphene nanoplatelets (GnPs)‐polypropylene (PP) nanocomposite fibers are reported for the first time. PP/GnPs fibers were spun with a pilot‐plant spinning machine with varying concentration of GnPs by mixing PP/GnPs masterbatch with PP. The effect of inclusion of GnPs on the morphology and crystalline structure of PP fibers was investigated. The thermal stability of the fibers was also evaluated by thermogravimetric analysis. The light microscopy images showed that the GnPs are uniformly distributed over the PP matrix. The differential scanning calorimetry (DSC) results revealed that presence of GnPs affects both the melting and crystallization behaviors. The melting peaks of PP/GnPs nanocomposite fibers were broader than that of neat PP fibers, indicating a broader crystal size distribution in PP/GnPs nanocomposite fibers as compared to the neat PP fibers. Besides, an obvious increment in the crystallization peak temperature was observed in GnPs‐PP nanocomposite fibers. The wide‐angle X‐ray diffraction spectra (WAXD) results showed that the crystal type of nanocomposite fibers did not change and was still the α‐monoclinic crystal form. Moreover, the morphology of spherulites demonstrated that GnPs increased the nucleation sites in the nanocomposite fibers which in turn restricted the crystal growth of PP chains. This finding supported the DSC and WAXD results. Activation energies were calculated by Horowitz and Metzger's method as 77.87 and 105.41 kJ/mol for neat PP and PP/0.2 wt% GnPs fibers, respectively, suggesting an increase in the thermal stability of GnPs‐PP nanocomposite fibers. POLYM. COMPOS., 36:367–375, 2015. © 2014 Society of Plastics Engineers     

Enhancing EAP-TLS authentication protocol for IEEE 802.11i

IEEE 802.11i authentication framework is composed of the 802.1x and an extensible authentication protocol (EAP) mechanism. One of the most applicable techniques in the EAP methods is EAP-transport layer security (EAP-TLS). The EAP-TLS implementation issues are high execution time; high number of data exchanges between two parties and possibility of closing connection as a result of modification in the contents of the handshake messages, which are all addressed in this paper. This research analyses the EAP-TLS in WLANs to improve this method’s efficiency in terms of the security analysis, time and memory usage. Based on the results, this research proposes an enhanced method with a discrete cryptographic mechanisms and a distinct handshake structure, which reduces the number of steps in the handshake protocol. This enhanced method also provides robust security compared to the original EAP-TLS with approximately the same level of memory usage, which reduces execution time significantly.     

A Demand-Based Structure for the Architecture of Wireless Networks on Chip

Wireless Personal Communications - Wireless networks on chip (WiNoC) are considered to be a novel approach for designing efficient and scalable systems. The rationale behind this new approach is to...     

Amino acid composition,antioxidant and functional properties of protein hydrolysates from the roe of rainbow trout (Oncorhynchus mykiss)

A fish roe protein hydrolysate from rainbow trout (Oncorhynchus mykiss) trout roe protein hydrolysates (TRH) was produced by pepsin and Alcalase. Proximate, amino acid compositions, protein digestibility and molecular mass distribution of the hydrolysates were determined. The degree of hydrolysis was found to be 44.08% and 27.62% (pepsin and Alcalase, respectively). The two hydrolysates contained a high amount of essential amino acids (33.53% Alcalase–29.39% pepsin). The results showed that TRH by different enzymes is a good source of the leucine and lysine amino acids. The pepsin produced a white powder with higher brightness (L* = 89.50). Alcalase hydrolysate was brownish yellow in colour (L* = 52.85, a* = 10.30, b* = 26.25). The hydrolysates represented excellent antioxidant activities in various concentrations. TRHs showed a good foaming and emulsification properties. The results thus revealed that protein hydrolysates from rainbow trout roe could be used as food additives possessing essential amino acids and antioxidant activity.     

Chemical and Biochemical Hydrolysis of Persian Sturgeon (Acipenser persicus) Visceral Protein

Chemical (pH 3.3, 70 °C, 85 °C; pH 12, 70 °C, 85 °C) and biochemical (Alcalase, Protamex, Neutrase, Flavourzyme, and Trypsin) hydrolysis of Persian sturgeon (Acipenser persicus) visceral protein was investigated. The results of this study revealed that there are significant differences between enzymes in terms of degree of hydrolysis (DH%; P < 0.05). Alcalase-hydrolyzed fish protein had the highest DH% (50.13%), and Trypsin-hydrolyzed fish protein had the minimum DH% (14.21%). The highest DH% in chemical hydrolysis was related to pH 3.3 at 85 °C (68.87%). The highest protein recovery (83.64%) and protein content (73.34) were related to enzymatic hydrolysis by Alcalase. The results of current study showed the significant effect of hydrolysis conditions on fish protein hydrolysate properties. Microbial enzymes could produce fish hydrolysates with higher degree of hydrolysis when compared to animal enzyme. Also, in chemical hydrolysis it is clear that hydrolysis at the lower pH and at higher temperature causes to more protein recovery and degree of hydrolysis.