Molecular structure and storage hardening of natural rubber: Insight into the reactions between hydroxylamine and phospholipids linked to natural rubber molecule

The effect of hydroxylamine on the molecular structure and storage hardening of natural rubber (NR) was investigated by the treatment of deproteinized NR (DPNR) latex with hydroxylamine. The hydroxylamine treatment decreased the content of long‐chain fatty acid ester groups in DPNR from about 2–0.7 mol per rubber molecule. The molecular weight and molecular weight distribution changed apparently after treatment with hydroxylamine. The relative intensity of the ¹H NMR signals corresponding to phospholipids at the α‐terminal group decreased after the hydroxylamine treatment. The Huggins ‘k’ constant of hydroxylamine‐treated DPNR showed the liberation of linear rubber molecules caused by decomposition of branch points derived from phospholipids. The absence of storage hardening in hydroxylamine‐treated DPNR was observed to be caused by not only the reaction of hydroxylamine and aldehyde groups but also the removal of phospholipids as well as the breakdown of phospholipid aggregations as a result of hydroxylamime, contributing to the establishment of a newly proposed mechanism of hydroxylamine on the inhibition of storage hardening in NR. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43753.     

Analysis of a 62 kb DNA sequence of chromosome X reveals 36 open reading frames and a gene cluster with a counterpart on chromosome XI

We have sequenced a 61.989 bp stretch located between genes RAD7 and FIP1 of Saccharomyces cerevisiae chromosome X. This stretch contains 36 open reading frames (ORFs) of at least 100 codons. Fourteen of these correspond to sequences previously published as HIT1, CDC8, YAP17, CBF1, NAT1, RPA12, CCT5, TOR1, RFC2, PEM2, CDC11, MIR1, STE18 and GRR1. The proteins deduced from four ORFs (YJR059w, YJR065c, YJR075w, YJR078w) have significant similarity to proteins of known function from yeast or other organisms, including S. cerevisiae serine/threonine-specific protein kinase. Schizosaccharomyces pombe Act2 protein, S. cerevisiae mannosyltransferase OCH1 protein and mouse indoleamine 2,3-dioxygenase, respectively. Four of the remaining 18 ORFs have similarity to proteins with unknown function, six are weakly similar to other known sequences, while another eight exhibit no similarity to any known sequence. In addition, three tRNA genes have been recognized. Three genes clustered within 22 kb (YJR059w, YJR061w and TOR1) have counterparts arranged within 15 kb on the left arm of chromosome XI.     

PICA: Backside failure analysis of CMOS circuits using Picosecond Imaging Circuit Analysis

Normal operation of complementary metal-oxide semiconductor (CMOS) devices entails the emission of picosecond pulses of light, which can be used to diagnose circuit problems. The pulses that are observed from submicron sized field effect transistors (FETs) are synchronous with logic state switching. Picosecond Imaging Circuit Analysis (PICA), a new optical imaging technique combining imaging with timing, spatially resolves individual devices at the 0.5 micron level and switching events on a 10 picosecond timescale. PICA is used here for the diagnostics of failures on two VLSI microprocessors.     

ATS-6 satellite 20 GHz propagation measurements at low elevation angles

The 20 GHz downlink from the ATS-6 satellite was monitored almost continuously for low elevation angles (below 9°). The authors measured the copolarised and crosspolarised signals received, as well as the local rain rate. Data are presented for clear-weather scintillations, rain attenuation, depolarisation and other effects.     

Notch geometry effects in fatigue: A conservative design approach

The understanding of stress concentrators (notches) is an important element in the prevention of failure in components and in the analysis of failures when they occur. This paper examines critically the methods currently used to predict the fatigue strength of components containing notches, with particular attention to the need for a conservative design approach. Current methods, if correctly applied, are shown to give conservative predictions of fatigue limit and high-cycle fatigue strength, and it is shown that the same philosophy can be extended to cover very small notches, including surface roughness. The presentation of these predictions in the form of a “mechanism map” for notch fatigue is advocated as a useful tool for designers. The problems of extending the approach to other types of stress concentrator, such as fillet radii, are discussed.     

Reducing and stabilizing the viscosity of natural rubber by using sugars: Interference of the Maillard reaction between proteins and sugars

This work is an extension of previous work elucidating the reduction and stabilization of solid natural rubber (NR) viscosity by using sugars. Various amounts of glucose, fructose, sucrose, and maltose were incorporated into fresh NR (FNR), deproteinized NR (DPNR), and synthetic polyisoprene (IR) latexes. The results revealed that all sugars cannot decrease the Mooney viscosity of FNR, while only monosaccharides, that is, glucose and fructose, can significantly decrease the Mooney viscosity of both DPNR and IR by way of a lubrication mechanism. The proteins in FNR can diminish the capability of glucose and fructose to decrease the Mooney viscosity. Furthermore, glucose was found to reduce the occurrence of storage hardening in DPNR by interacting with polar groups of phospholipids at the rubber chain ends. Measurements of browning intensity as well as analysis of Maillard reaction products together with the NR protein–glucose model compound were utilized to confirm that the reduction and stabilization of the viscosity of NR using monosaccharides were interfered by the Maillard reaction between the proteins in NR and the monosaccharides.     

Hybrid Metamodeling/Metaheuristic Assisted Multi-Transmitters Placement Planning

With every passing day, the demand for data traffic is increasing, and this urges the research community not only to look for an alternating spectrum for communication but also urges radio frequency planners to use the existing spectrum efficiently. Cell sizes are shrinking with every upcoming communication generation, which makes base station placement planning even more complex and cumbersome. In order to make the next-generation cost-effective, it is important to design a network in such a way that it utilizes the minimum number of base stations while ensuring seamless coverage and quality of service. This paper aims at the development of a new simulation-based optimization approach using a hybrid metaheuristic and metamodel applied in a novel mathematical formulation of the multi-transmitter placement planning (MTPP) problem. We first develop a new mathematical programming model for MTPP that is flexible to design the locations for any number of transmitters. To solve this constrained optimization problem, we propose a hybrid approach using the radial basis function (RBF) metamodel to assist the particle swarm optimizer (PSO) by mitigating the associated computational burden of the optimization procedure. We evaluate the effectiveness and applicability of the proposed algorithm by simulating the MTPP model with two, three, four and five transmitters and estimating the Pareto front for optimal locations of transmitters. The quantitative results show that almost maximum signal coverage can be obtained with four transmitters; thus, it is not a wise idea to use higher number of transmitters in the model. Furthermore, the limitations and future works are discussed.     

Multiphoton ionization of rare gases at 1.06µ and 0.53µ

The interaction between an intense focused beam of optical photons and matter in gaseous form at low pressure (10^-3torr) brings into play some strongly nonlinear processes. These multiphoton processes occur through the simultaneous absoprtion of several quanta by an atom that may be thus either excited or ionized. The orders of nonlinearity of the interaction of a multimodeQ-switched laser beam with rare gas atoms were measured with laser intensities up to 10¹³W ċcm^-2at 1.06μ and up to 10¹²W ċcm^-2at 0.53μ. The energy of the number of quanta corresponding to the order of nonlinearity is always close to the energy of an atomic level. The results seem to emphasize the particularly important role performed by bound states during the ionization process. Thus a two-stage ionization process seems far more probable than a single direct transition between the ground state and the continuum spectrum. Experimental values of multiphoton ionization probabilities are also given after having precisely determined the spatiotemporal intensity distribution function.