CCH: a clique based asymmetric rendezvous scheme for cognitive radio ad-hoc networks

Wireless Networks - Rendezvous (RDV) in cognitive radio ad-hoc networks (CRAHNs) is one of the key ways for a pair of unknown cognitive radio users to initiate communications. CRAHN is a...     

Pregnancy by Assisted Reproductive Technology Is Associated with Shorter Telomere Length in Neonates

Telomere length (TL) influences the development of lifestyle-related diseases, and neonatal TL may influence their prevalence. Various factors have been reported to affect neonatal TL. Although the fetus is exposed to multiple conditions in utero, the main factors affecting the shortening of neonatal TL are still not known. In this study, we sought to identify factors that influence fetal TL. A total of 578 mother-newborn pairs were included for TL analysis. TL was measured in genomic DNA extracted from cord blood samples using quantitative PCR. The clinical factors examined at enrollment included the following intrauterine environmental factors: maternal age, assisted reproductive technology (ART) used, body mass index (BMI), gestational diabetes mellitus (GDM), maternal stress, smoking, alcohol consumption, preterm delivery, small-for-gestational-age, neonatal sex, and placental weight. Univariate and multivariate regression analyses were used to verify the relationship between neonatal TL and these clinical factors. The median neonatal TL to single-copy gene ratio was 1.0. Pregnancy with ART was among the 11 factors associated with shorter neonatal TL. From multiple regression analysis, we determined that neonatal TL was significantly shorter for pregnancies in the ART group than in the other groups. We conclude that pregnancy with ART is associated with shorter neonatal TL.     

Study of the Antioxidative Properties of Several Amino Acid-Type Surfactants and their Synergistic Effect in Mixed Micelle

Cysteine and methionine, two sulfur-containing amino acids (AA), were introduced in their surfactant forms as potential antioxidants. The antioxidative (AOX) properties of lauroyl methionine (C12-Met) and lauroyl cysteine (C12-Cys) was investigated by means of the oxygen radical absorbance capacity assay. Both the surfactants exhibited excellent AOX behavior at the premicellar state and micellar medium. The AOX behavior was found to be comparable for both the surfactants at their premicellar states. However, in micellar medium, C12-Met showed better AOX property than C12-Cys. The AOX power of the surfactants was compared with other previously developed AA-type surfactants. The order of the AOX power was found to be: C12-tryptophan > C12-tyrosine ≈ C12-methionine ≈ C12-cysteine > C12-histidine at the premicellar state and C12-tryptophan > C12-tyrosine > C12-methionine > C12-cysteine > C12-histidine at the micellar state. C12-Cys displayed lower AOX property in micellar medium due to its dimer formation tendency. Based on the HPLC and UPLC-Q-TOF-MS analysis, the dimer formation of C12-Cys was found to be accelerated due to the micellar environment and results into negative synergistic effect on other aromatic AA-type surfactants. However, the presence of C12-His in the micellar solution of C12-Cys resulted no synergistic effect due to stronger H-bonding between the surfactants and resulting less dimer formation.     

Cellular Disulfide Bond Formation in Bioactive Peptides and Proteins

Bioactive peptides play important roles in metabolic regulation and modulation and many are used as therapeutics. These peptides often possess disulfide bonds, which are important for their structure, function and stability. A systematic network of enzymes—a disulfide bond generating enzyme, a disulfide bond donor enzyme and a redox cofactor—that function inside the cell dictates the formation and maintenance of disulfide bonds. The main pathways that catalyze disulfide bond formation in peptides and proteins in prokaryotes and eukaryotes are remarkably similar and share several mechanistic features. This review summarizes the formation of disulfide bonds in peptides and proteins by cellular and recombinant machinery.     

Kinetic analysis of magnesium aluminate spinel formation: Effect of MgO:Al2O3 ratio and titania dopant

The mechanistic pathway of MgO-Al₂O₃ reaction in solid state to form MgAl₂O₄ spinel was investigated to correlate the kinetic parameters with ratio of reactants (MgO:Al₂O₃) and with the presence of a doping agent, TiO₂. The time-temperature-expansion data of oxide compacts was analyzed using several model free analyses and model based (linear and non-linear) kinetic algorithms. These indicated that spinel formation process can be best described by single step with n-dimensional Avrami equation for every MgO:Al₂O₃ ratio, irrespective of titania dopant. The activation energy (E_a) of the process was proportional to % spinel formed in each system and validated with quantitative XRD analysis. The higher value of Avrami coefficient (n) in 90 wt% Al₂O₃ compositions has been explained with geometric considerations of powder packing. Incorporations of 1% TiO₂ in the MgO: Al₂O₃ oxide compact did not markedly affect the reaction model, frequency factor and Activation energy.     

Waves in generalized thermo-viscoelastic infinite continuum with cylindrical cavity due to three-phase-lag time-nonlocal heat transfer

Abstract

Generalized thermoelastic interactions due to three-phase-lag time-nonlocal heat transfer in a Kelvin-Voigt type infinitely extended visco-thermoelastic continuum with cylindrical cavity has been investigated. The two-temperature generalized thermoelasticity theory has also been taken into account. The problem has been solved in the domain of Laplace on the assumption that the surface of the cavity is free from traction and is subjected to a smooth and time-dependent-heating effect. Laplace inversion of the transformed solutions has been carried out numerically. The obtained numerical data for different considerations are plotted in graphs to study the effects of time-nonlocal parameter, two-temperature parameter and visco-thermoelastic relaxation parameter on different thermoelastic quantities of physical interest.     

Effects of metal support interaction on dry reforming of methane over Ni/Ce-Al2O3 catalysts

Dry (CO₂) reforming of methane is conducted over two newly synthesized Ni20/Ce-γAl₂O₃ and Ni20/Ce-meso-Al₂O₃ catalysts. The x-ray diffraction (XRD) patterns indicated that Ni20/Ce-meso-Al₂O₃ exhibits a better dispersion of nickel, while Ni20/Ce-γAl₂O₃ has larger amounts of nickel crystallites. The temperature programmed desorption (TPD) kinetics analysis indicated that Ni20/Ce-meso-Al₂O₃ had a lesser metal-support interaction than the Ni20/Ce-γAl₂O₃. The thermal gravimetric analysis (TGA) indicated that the incorporation of ceria into the Al₂O₃ matrix helps to stabilize Ni20/Ce-meso-Al₂O₃ during dry reforming of methane. The temperature programmed reduction (TPR) indicated that the synthesized catalysts were sufficiently reducible below 750 °C. A fixed bed reactor evaluation (at 750 °C) showed that both catalysts can facilitate methane reforming to syngas with minimal coking throughout the 30 hours time-on-stream (TOS). However, Ni20/Ce-meso-Al₂O₃ is more promising in terms of prolonged stability for dry reforming applications. Moreover, the syngas yield for Ni20/Ce-γAl₂O₃ is close to equilibrium prediction during the first 1 hour of reaction time.     

A Distance Based Communication Mode Selection Mechanism for M2M Communications Over Cellular Networks

The implementation of machine-to-machine (M2M) communications in fifth-generation (5G) cellular networks can facilitate with several benefits like enhancement of bandwidth utilization, accommodating large number of users and decreasing traffic load on evolved node B (eNB). Integration of location information of unknown machine in communication mode selection mechanism is the key feature of this research. In this paper, a distance based communication mode selection mechanism using non-orthogonal resource sharing scheme is adopted in the proposed system model. Under the proposed mechanism, the expressions of throughput and RBs utilization policy are derived, which are the key parameters to evaluate the performance in the proposed network. Depending on the mode selection condition, such as threshold distance and threshold SINR between M2M users and regular cellular users, a UE can automatically choose its communication mode in the network. It is supposed that selection of mode before data transfer can improve the system performance. On the other hand, designing of efficient distance assisted proposed resource blocks (RBs) utilization policy reduces the traffic load on the eNB. Extensive simulations are carried out for evaluating the performance of the proposed mechanisms. The system performance is compared with various changeable parameters, such as throughput, mode selection threshold SINR, threshold distance and RBs. Besides, the proposed mechanism provides better network performance as well as reduces the traffic load in the proposed network.