Enhanced forward stimulated Brillouin scattering in silicon photonic slot waveguide Bragg grating

We study the forward stimulated Brillouin scattering process in a suspended silicon slot waveguide Bragg grating. Full-vectorial formalism is applied to analyze the interplay of electrostriction and radiation pressure. We show that radiation pressure is the dominant factor in the proposed waveguide. The Brillouin gain strongly depends on the structural parameters and the maximum value in the order of 106 W−1 m−1 is obtained in the slow light regime, which is more than two orders larger than that of the stand-alone strip and slot waveguides

All-optical non-volatile tuning of an AMZI-coupled ring resonator with GST phase-change material

We present a Ge2Sb2Te5 (GST)-integrated ring resonator with the tuning enabled by an all-optical phase change of GST using a sequence of optical pulses. The tuning is non-volatile and repeatable, with no static power consumption due to the “self-holding” feature of the GST phase-change material. The 2 μm long GST can be partially crystallized by controlling the number of pulses, increasing the tuning freedom. The coupling between the ring resonator and the bus waveguide is based on an asymmetric Mach–Zehnder interferometer. The coupling strength is wavelength-dependent, so that an optimal wavelength can be selected for the probe light to get more than 20 dB transmission contrast between the amorphous and crystalline GST states

Geographical effects on epidemic spreading in scale-free networks

Many real networks are embedded in a metric space: the interactions among individuals depend on their spatial distances and usually take place among their nearest neighbors. In this paper, we introduce a modified susceptible-infected-susceptible (SIS) model to study geographical effects on the spread of diseases by assuming that the probability of a healthy individual infected by an infectious one is inversely proportional to the Euclidean distance between them. It is found that geography plays a more important role than hubs in disease spreading: the more geographically constrained the network is, the more highly the epidemic prevails.Comment: 4 pages, 5 figure

Improved Performances Of Metal-Oxide-Nitride-Oxide-Silicon Memory With Hftion as Charge Trapping Layer

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Molecular cloning and characterization of a cytoplasmic cyclophilin gene in sugarcane

Cyclophilins are ubiquitous proteins with an enzymatic activity of peptidyl-prolyl cis-trans isomerase (PPIase), which play important roles in a variety of stress responsiveness. In this study, we reported the cloning and characterization of a full-length cytoplasmic cyclophilin gene in sugarcane. Sequence analysis showed the cDNA of this gene (GenBank accession number:GQ246462), termed as Sc-CyP, was 904 bp long, including a 519 bp complete ORF, the 5’ UTR of 74 bp and 3’UTR of 311 bp, plus a typical AATAA motif and poly (A) tail. It encoded the 172 amino acid polypeptide with a molecular weight of 18.4 KD and the isoelectric point of 8.68. The Sc-CyP encoding protein had the conserved site Trp128 (W128) ubiquitious of all cyclophilins in eukaryotes and the KSGKPLH48-54 region specific to cytoplasmic cyclophilins in plants. SDS-PAGE analysis and PPIase assay revealed that the expression product, with PPIase activity, was a fusion protein with a molecular weight about 25 and 18.4 kD of Sc- CyP plus 7 kD of His • Tag peptides. In real-time qPCR analysis, the Sc-CyP gene showed induced expression under PEG, NaCl, SA and H2O2 stresses, indicating it a stress-related gene for drought and salt stress, signal transduction and disease resistance response in sugarcane.Key words: Sugarcane (Saccharum officinarum), cyclophilin, PPIase, real-time quantitative PCR

Molecular cloning and expression analysis of a zeta-class glutathione S-transferase gene in sugarcane

Glutathione S-transferases (GSTs) play an important role in stress tolerance in plants. This is the first report of cloning and characterization of a zeta-class GST gene in sugarcane (GenBank Accession number: GQ246461). Sequence analysis showed that the cDNA sequence of Sc-GST gene was 829 bp, contained a 621 bp open reading frame (ORF), the 5’ untranslated region (UTR) of 65 bp and 3’UTR of 143 bp, plus the typical AATAA region and poly (A) tail. It encoded the 206 amino acid residues with a molecular mass of 23.1 KD and isoelectric point of 6.10. Protein domain prediction and multiple sequence alignment demonstrated that the conserved domain in Sc-GST at N-terminus was SSCXXRXRIA, while that at C-terminus was quebec platelet disorder (QPD), both of which were specific for zeta-type GST in eukaryotes. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis and enzyme activity assay indicated that the prokaryotic expression product was a fusion protein with a molecular weight of about 30 KD, which also possessed GST enzyme activity. It was revealed in real-time quantitative polymerase chain reaction (qPCR) analysis that the Sc-GST gene had induced expression under H2O2 and Ustilago scitaminea stresses, while it was inhibited and then induced by salicylic acid (SA) stress, suggesting that it is a type of stress-tolerant gene playing a certain role in sugarcane resistance response.Key words: Saccharum officinarum, glutathione S-transferase, homology, prokaryotic expression, real-time quantitative PCR