Pulse compression by filamentation in argon with an acoustic optical programmable dispersive filter for predispersion compensation

We have experimentally demonstrated pulses 0.4 mJ in duration smaller than 12 fs; with an excellent spatial beam profile by self-guided propagation in argon. The original 52 fs pulses from the chirped pulsed amplification laser system are first precompressed to 32 fs by inserting an acoustic optical programmable dispersive filter instrument into the laser system for spectrum reshaping and dispersion compensation, and the pulse spectrum is subsequently broadened by filamentation in an argon cell. By using chirped mirrors for post-dispersion compensation, the pulses are successfully compressed to smaller than 12 fs.

Single attosecond pulse generation in He+ by controlling the instant ionization rate using attosecond pulse trains combined with an intense laser pulse

High-order harmonics and single attosecond pulse generation by using an infrared laser pulse combined with attosecond pulse trains (APT) interacting with He+ have been investigated. We show that the ionization for different instant time intervals can be controlled by altering the time delay between the APT and the infrared pulse. Consequently, APT can be used as a tool to control the efficiency of high-order harmonics emitted at different times. By choosing appropriate APT and time delay, the driving pulse width for single attosecond pulse generation can be extended up to six optical cycles. (c) 2007 Optical Society of America.

Characteristics of high reflection mirror with an SiO2 top layer for multilayer dielectric grating

The high reflection (HR) mirror composed of dielectric stacks with excellent spectrum characteristics and high damage resistant ability is critical for fabricating multilayer dielectric (MLD) grating for pulse compressor. The selection of the SiO2 material as the top layer of the HR mirror for grating fabrication is beneficial for improving the laser-induced damage threshold of MLD grating as well as minimizing the standing-wave effect in the photoresist during the exposure process. Based on an (HLL) H-9 design comprising quarter-waves of HfO2 ( H) and half-waves of SiO2 ( L), we obtain an optimal design of the HR mirror for MLD grating, the SiO2 top layer of which is optimized with a merit function including both the diffraction efficiency of the MLD grating and the electric field enhancement in the grating. Dependence of the performance of the MLD grating on the fabrication error of the dielectric mirror is analysed in detail. The HR mirror is also fabricated by E-beam evaporation, which shows good spectral characteristics at the exposure wavelength of 413 nm and at the operation wavelength of 1053 nm and an average damage threshold of 10 J cm(-2) for a 12 ns pulse.

Guided-mode resonant grating filter with an antireflective surface for the multiple channels

In this paper, a new type of guided-mode resonant grating (GMRG) filter with an antireflective surface called the 'moth-eye structure' for the multiple channels is presented by using rigorous coupled-wave analysis (RCWA) and the S-matrix method. Long range, low sidebands and multiple channels are found when the GMRG filters with antireflective surface are illuminated with incident polarization light. It is calculated that the multiple channel phenomenon can be shown when the depth of antireflective surface is increased. Moreover, the wavelengths of the multiple channels can be easily shifted by changing the depth of the homogenous layer which is under the antireflective surface, and the optical properties of GMRG filters such as low sideband reflection and narrow band are not badly spoiled when the depth is changed.

Isatisine a, a novel alkaloid with an unprecedented skeleton from leaves of isatis indigotica

9 alpha,13 alpha-Dihydroxylisopropylidenylisatisine A (1), which was derived from isatisine A (2) and possessed an unprecedented fused pentacyclic skeleton, was isolated from the leaves of Isatis indigotica Fort. The structure and relative configuration w

Przewalskin B, a novel diterpenoid with an unprecedented skeleton from Salvia przewalskii maxim

[GRAPHIC] Przewalskin B (1), a novel diterpenoid possessing a unique skeleton, was isolated from a Chinese medicinal plant Salvia przewalskii. Its structure and relative stereochemistry were elucidated by extensive NMR analysis and a single-crystal X-ray

Schilancidilactones A and B: two novel tetranortriterpenoids with an unprecedented skeleton from Schisandra lancifolia

Schilancidilactones A (1) and B (2). two novel tetranortriterpenoids possessing an unprecedented skeleton, have been isolated from the stems of Schisandra lancifolia. Their structures were elucidated on the basis of extensive spectroscopic analysis. The r

Phylogenetic relationships among Rhacophorinae (Rhacophoridae, Anura, Amphibia), with an emphasis on the Chinese species

The partial nucleotide sequence of mitochondrial 12S and 16S rRNA genes was determined for 23 Chinese species of Rhaeophoridae (Amphibia: Anura), representing four of the eight recognized genera. Using Buergeriinae as the outgroup, phylogenetic analyses (

Effects of gamma-aminobutyric acid, progesterone and ionophore A23187 on acrosome reaction of tree shrew sperm in vitro: examination of acrosome reaction with an improved fluorescence microscopy

A number of acrosome reaction (AR) initiators have been found to be effective in inducing AR of human, laboratory and domestic animal sperm. Using an improved simple fluorescence microscopy, effects of gamma-aminobutyric acid (GABA), progesterone and ionophore A23187 on sperm AR of tree shrew, a useful animal model in biomedical research, have been investigated. Spontaneous AR in 4.92-7.53% of viable sperm was observed. Complete AR in 10.31-18.25% of viable tree shrew sperm was obviously induced by 5 mu M and 10 mu M calcium ionophore A23187, 1 mM GABA, and 5 mu M progesterone, and there were no significant differences between their abilities to initiate complete AR. No significant differences of AR percentages between 1- and 2-h treatments with A23187, progesterone and/or GABA were observed. These results suggested that the responses of tree shrew sperm to these AR initiators are similar to that of human and other mammalian sperm. (C) 1997 Elsevier Science B.V.

Phylogenetic analysis of the family Thermaceae with an emphasis on signature position and secondary structure of 16S rRNA

The sequences of the 16S rRNA genes from 38 strains of the family Thermaceae were compared by alignment analysis. The genus-specific and species-specific base substitutions or base deletions (signature positions) were found in three hypervariable regions (in the helices 6, 10 and 17). The differentiation of secondary structures of the high variable regions in the 5' end (38-497) containing several signature positions further supported the concept. Based on the comparisons of the secondary structures in the segments of 16S rRNAs, a key to the species of the family Thermaceae was proposed. (C) 2003 Published by Elsevier Science B.V. on behalf of the Federation of European Microbiological Societies.

Genomic sequence of mandarin fish rhabdovirus with an unusual small non-transcriptional ORF

The complete genome of mandarin fish Siniperca chuatsi rhabdovirus (SCRV) was cloned and sequenced. It comprises 11,545 nucleotides and contains five genes encoding the nucleoprotein N, the phosphoprotein P, the matrix protein M, the glycoprotein G, and the RNA-dependent RNA polymerase protein L. At the 3' and 5' termini of SCRV genome, leader and trailer sequences show inverse complementarity. The N, P, M and G proteins share the highest sequence identities (ranging from 14.8 to 41.5%) with the respective proteins of rhabdovirus 903/87, the L protein has the highest identity with those of vesiculoviruses, especially with Chandipura virus (44.7%). Phylogenetic analysis of L proteins showed that SCRV clustered with spring vireamia of carp virus (SVCV) and was most closely related to viruses in the genus Vesiculovirus. In addition, an overlapping open reading frame (ORF) predicted to encode a protein similar to vesicular stomatitis virus C protein is present within the P gene of SCRV. Furthermore, an unoverlapping small ORF downstream of M ORF within M gene is predicted (tentatively called orf4). Therefore, the genomic organization of SCRV can be proposed as 3' leader-N-P/C-M-(orf4)-G-L-trailer 5'. Orf4 transcription or translation products could not be detected by northern or Western blot, respectively, though one similar mRNA band to M mRNA was found. This is the first report on one small unoverlapping ORF in M gene of a fish rhabdovirus. (c) 2007 Elsevier B.V. All rights reserved.

Observations on two species of phyllodistomes (Trematoda : Gorgoderidae) from fishes of the Hubei Province, central China, with an erection of Neophyllodistomum gen. n.

Two rare trematode species so far reported in the genus Phyllodistomum Braun, 1899, P. pawlovskii (Zmeev, 1936) and P. serrispatula Chin, 1963, were found in the urinary system the yellow catfish Pelteobagrus fulvidraco (Richardson) of Bao'an Lake (prevalence 8 %) and the swamp eel Monopterus albus (Zouiev) of Liangzi Lake (prevalence 6 9/6), respectively, from the Hubei Province, central China. In contrast to the original description, P. pawlovskii showed a considerable morphological variability particularly in the shape, size and topography of testes. A unique morphological feature of P. serrispatula is the presence of many conspicuous lateral outgrowths on the hindbody and, principally based on this character, a new genus Neophyl-lodistomum is erected (type species N. serrispatula (Chin, 1963) comb. n.)) to accommodate this species. Both trematode species are briefly redescribed. P. pawlovskii and N. serrispatula are reported for the first time from the Hubei Province and the former from the Yangtze River drainage system.