Extreme ultraviolet multilayer mirror with near-zero IR reflectance.

We have developed a multilayer mirror for extreme ultraviolet (EUV) radiation that has low reflectance for IR radiation at 10.6 mum wavelength. The mirror is based on a multilayer coating comprising alternating layers of diamondlike carbon and silicon, for which we demonstrate an EUV reflectance of up to 49.7%. We have made a functional prototype in which the multilayer coating is included as part of an antireflection coating for IR radiation, resulting in reflectance values of 42.5% and 4.4% for EUV and IR, respectively. The mirror can replace a standard Mo/Si mirror in an EUV lithography tool to form an efficient solution for the suppression of unwanted CO(2) laser radiation.

Cognitive coping and goal adjustment after first-time myocardial infarction: relationships with symptoms of depression.

The authors studied the relationships among cognitive coping strategies, goal adjustment processes (disengagement and reengagement), and depressive symptomatology in a sample of 139 patients who had experienced a first-time acute myocardial infarction between 3 and 12 months before data assessment. They assessed cognitive coping strategies, goal adjustment, and depressive symptoms by the Cognitive Emotion Regulation Questionnaire, the Goal Obstruction Questionnaire, and the Hospital Anxiety and Depression Scale, respectively. Main statistical methods were Pearson correlations and multiple regression analyses. Results show significant associations among the cognitive coping strategies of rumination, catastrophizing, and higher depressive symptoms, as well as among positive refocusing, goal reengagement, and lower depressive symptoms. This suggests that cognitive coping and goal reengagement strategies may be useful targets for intervention.

Spectral-purity-enhancing layer for multilayer mirrors.

We demonstrate, both theoretically and experimentally, that special spectral-purity-enhancing multilayer mirror systems can be designed and fabricated to substantially reduce the level of out-of-band radiation expected in an extreme ultraviolet lithographic tool. A first proof of principle of applying such spectral-purity-enhancement layers showed reduced out-of-band reflectance by a factor of five, while the in-band reflectance is only 4.5% (absolute) less than for a standard capped multilayer.

Continuous-wave operation of a single-frequency optical parametric oscillator at 4-5 microm based on periodically poled LiNbO3.

We present a cw, Nd:YAG-pumped singly resonant single-frequency narrow-linewidth high-power optical parametric oscillator with idler tuning from 3.7 to 4.7 microm. In this spectral range the absorption of the idler wave in the LiNbO3 crystal is significant, causing the oscillation threshold to increase with a subsequent decrease in output power from 1.2 W at 3.9 microm to 120 mW at 4.7 microm. The optical parametric oscillator's cavity was stabilized and mode-hop tuned with a rotatable solid etalon but with a subsequent reduction in idler power of as much as 50%. We demonstrated the usefulness for spectroscopy by recording the photoacoustic spectrum of a strong CO2 absorption, using a 24-GHz continuous idler scan.

Wide single-mode tuning of a 3.0- 3.8-mum, 700-mW, continuous-wave Nd:YAG-pumped optical parametric oscillator based on periodically poled lithium niobate.

A new optical parametric oscillator (OPO) for the mid-infrared wavelength region of 3-3.8mum with an idler output power of up to 1.5 W has been developed. The singly resonant OPO is pumped by a single-mode, 10-W, continuous-wave Nd:YAG laser and consists of a bow-tie ring cavity with a fan-out periodically poled lithium niobate crystal and a low-finesse intracavity air-spaced etalon. The single-frequency idler output can be continuously tuned over 24 GHz with 700-mW power by tuning of the pump laser. The tuning was demonstrated by recording of an absorption line of ethane with photoacoustic spectroscopy.

Expression in anthers of two genes encoding Brassica oleracea transmembrane channel proteins.

Screening of an anther cDNA expression library resulted in the isolation of two almost identical cDNA clones, termed mipA and mipB, showing homology with sequences encoding transmembrane channel proteins from the MIP family. Both clones were expressed in several tissues, but not in pollen. MipA was preferentially expressed in the surrounding sporophytic tissues of stamens. Anthers subjected to drought were induced to accumulate even more mip transcripts, which was entirely due to higher mipA gene expression. On basis of isolation procedures, sequence homology and drought inducibility of mipA we conclude that the encoded proteins probably are constituents of the pollen coat and are aquaporins.

Expression of an isoflavone reductase-like gene enhanced by pollen tube growth in pistils of Solanum tuberosum.

Successful sexual reproduction relies on gene products delivered by the pistil to create an environment suitable for pollen tube growth. These compounds are either produced before pollination or formed during the interactions between pistil and pollen tubes. Here we describe the pollination-enhanced expression of the cp100 gene in pistils of Solanum tuberosum. Temporal analysis of gene expression revealed an enhanced expression already one hour after pollination and lasts more than 72 h. Increase in expression also occurred after touching the stigma and was not restricted to the site of touch but spread into the style. The predicted CP100 protein shows similarity to leguminous isoflavone reductases (IFRs), but belongs to a family of IFR-like NAD(P)H-dependent oxidoreductases present in various plant species.

Regulation of flavonol biosynthesis during anther and pistil development, and during pollen tube growth in Solanum tuberosum.

The regulation of flavonol biosynthesis was studied in anthers and pistils of Solanum tuberosum. Flavonols are essential for functional pollen tube growth in a number of species. Flavonol accumulation in whole anthers started at the unicellular stage of pollen development and continued until pollen maturity. A cDNA clone encoding flavonol synthase (FLS) was isolated. Fls gene expression was detected in pistils, anthers, petals and ovaries, the organs in which flavonols are accumulating. Fls transcripts were present in unicellular and bicellular pollen, but not in mature pollen. The expression patterns of three genes encoding enzymes in the flavonoid biosynthetic pathway, chalcone synthase (chs), flavanone-3-hydroxylase and fls were analysed in developing anthers and pistils. Only chs transcripts accumulated concomitantly with the flavonols in anthers. In pistils of potato, pollen tube growth induced an increase in fls gene expression that, unlike the situation in pollinated pistils of petunia, did not result in an increased flavonol content. Flavonol biosynthesis in anthers is probably initiated by the expression of the chs gene, and flavonol accumulation in pistils upon pollen tube growth is not an universal phenomenon.

Molecular analysis of a pistil-specific gene expressed in the stigma and cortex of Solanum tuberosum.

A gene, sts14, coding for a highly expressed mRNA in pistils of Solanum tuberosum, was isolated. Northern blot and in situ analyses demonstrated that the gene was expressed throughout pistil development in both the stylar cortex and the stigma. The deduced STS14 protein displays similarity to the pathogenesis-related PR-1 proteins. A possible function for protection or guidance of the pollen tubes through the pistil is discussed.

Characterization of a pollen-specific cDNA clone from Nicotiana tabacum expressed during microgametogenesis and germination.

This report describes the isolation and characterization of a cDNA clone representing a gene specifically expressed in pollen. A cDNA library was constructed against mRNA from mature pollen of Nicotiana tabacum. It was screened differentially against cDNA from mRNA of leaf and of pollen. One clone, NTPc303, was further characterized. On northern blot this clone hybridizes to a transcript 2100 nucleotides in length. NTPc303 is abundant in pollen. Expression of the corresponding gene is restricted to pollen, because no other generative or vegetative tissue contains transcripts hybridizing to NTPc303. Expression of NTP303 is evolutionarily conserved: homologous transcripts are present in pollen from various plant species. The first NTP303 transcripts are detectable on northern blot at the early bi-nucleate stage and accumulate until the pollen has reached maturity. During germination and pollen tube growth in vitro new NTP303 transcripts appear. This transcription has been proved by northern blots as well as by pulse labelling experiments. Nucleotide sequence analysis revealed that NTPc303 has an open reading frame coding for a predicted protein of 62 kDa. This protein shares homology to ascorbate oxidase and other members of the blue copper oxidase family. A possible function for this clone during pollen germination is discussed.

Stage-related expression of mRNAs during pollen development in lily and tobacco.

Homogeneous populations of developing microspores and pollen from anthers of lily (Lilium longiflorum Thumb.) and tobacco (Nicotiana tabacum L.) show a continuous production of biomass, reaching a maximum in young pollen. The rate of RNA synthesis was 460 fg · h(-1) in young binucleate cells, 138 fg · h(-1) in late binucleate cells and 56 fg · h(-1) in microspores. The mRNA population in developing pollen can be separated into three groups. In the first group, certain types of mRNAs are present at a constant level during all stages of development. A second group is characteristic of young pollen and increases quantitatively until anthesis. A third group is seen transiently; to this belong mRNAs present only before mitosis or at a distinct cell stage after mitosis. Some of the translation products of this latter group of mRNAs showed similarities between lily and tobacco on two-dimensional gels in respect of molecular weight and isolectric point, indicating that those mRNAs and proteins play a role in the regulation of pollen development.