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  • 1
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 2015
    In:  Proceedings of the National Academy of Sciences Vol. 112, No. 47 ( 2015-11-24), p. 14479-14483
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 112, No. 47 ( 2015-11-24), p. 14479-14483
    Abstract: Transient electric fields, which are an important but hardly explored parameter of laser plasmas, can now be diagnosed experimentally with combined ultrafast temporal resolution and field sensitivity, using femtosecond to picosecond electron or proton pulses as probes. However, poor spatial resolution poses great challenges to simultaneously recording both the global and local field features. Here, we present a direct 3D measurement of a transient electric field by time-resolved electron schlieren radiography with simultaneous 80-μm spatial and 3.7-ps temporal resolutions, analyzed using an Abel inversion algorithm. The electric field here is built up at the front of an aluminum foil irradiated with a femtosecond laser pulse at 1.9 × 10 12 W/cm 2 , where electrons are emitted at a speed of 4 × 10 6 m/s, resulting in a unique “peak–valley” transient electric field map with the field strength up to 10 5 V/m. Furthermore, time-resolved schlieren radiography with charged particle pulses should enable the mapping of various fast-evolving field structures including those found in plasma-based particle accelerators.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
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    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2015
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  • 2
    Online Resource
    Online Resource
    American Association for the Advancement of Science (AAAS) ; 2022
    In:  Science Vol. 378, No. 6618 ( 2022-10-28), p. 371-376
    In: Science, American Association for the Advancement of Science (AAAS), Vol. 378, No. 6618 ( 2022-10-28), p. 371-376
    Abstract: A coherent interface design makes brittle silicon nitride ceramics deformable mediated by a stress-induced phase transformation.
    Type of Medium: Online Resource
    ISSN: 0036-8075 , 1095-9203
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    Language: English
    Publisher: American Association for the Advancement of Science (AAAS)
    Publication Date: 2022
    detail.hit.zdb_id: 128410-1
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  • 3
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 2014
    In:  Proceedings of the National Academy of Sciences Vol. 111, No. 16 ( 2014-04-22), p. 5825-5830
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 111, No. 16 ( 2014-04-22), p. 5825-5830
    Abstract: Desktop laser plasma acceleration has proven to be able to generate gigaelectronvolt-level quasi-monoenergetic electron beams. Moreover, such electron beams can oscillate transversely (wiggling motion) in the laser-produced plasma bubble/channel and emit collimated ultrashort X-ray flashes known as betatron radiation with photon energy ranging from kiloelectronvolts to megaelectronvolts. This implies that usually one cannot obtain bright betatron X-rays and high-quality electron beams with low emittance and small energy spread simultaneously in the same accelerating wave bucket. Here, we report the first (to our knowledge) experimental observation of two distinct electron bunches in a single laser shot, one featured with quasi-monoenergetic spectrum and another with continuous spectrum along with large emittance. The latter is able to generate high-flux betatron X-rays. Such is observed only when the laser self-guiding is extended over 4 mm at a fixed plasma density (4 × 10 18 cm −3 ). Numerical simulation reveals that two bunches of electrons are injected at different stages due to the bubble evolution. The first bunch is injected at the beginning to form a stable quasi-monoenergetic electron beam, whereas the second one is injected later due to the oscillation of the bubble size as a result of the change of the laser spot size during the propagation. Due to the inherent temporal synchronization, this unique electron–photon source can be ideal for pump–probe applications with femtosecond time resolution.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
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    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2014
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
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  • 4
    In: Nature, Springer Science and Business Media LLC, Vol. 609, No. 7926 ( 2022-09-08), p. 341-347
    Abstract: Monoterpene indole alkaloids (MIAs) are a diverse family of complex plant secondary metabolites with many medicinal properties, including the essential anti-cancer therapeutics vinblastine and vincristine 1 . As MIAs are difficult to chemically synthesize, the world’s supply chain for vinblastine relies on low-yielding extraction and purification of the precursors vindoline and catharanthine from the plant Catharanthus roseus , which is then followed by simple in vitro chemical coupling and reduction to form vinblastine at an industrial scale 2,3 . Here, we demonstrate the de novo microbial biosynthesis of vindoline and catharanthine using a highly engineered yeast, and in vitro chemical coupling to vinblastine. The study showcases a very long biosynthetic pathway refactored into a microbial cell factory, including 30 enzymatic steps beyond the yeast native metabolites geranyl pyrophosphate and tryptophan to catharanthine and vindoline. In total, 56 genetic edits were performed, including expression of 34 heterologous genes from plants, as well as deletions, knock-downs and overexpression of ten yeast genes to improve precursor supplies towards de novo production of catharanthine and vindoline, from which semisynthesis to vinblastine occurs. As the vinblastine pathway is one of the longest MIA biosynthetic pathways, this study positions yeast as a scalable platform to produce more than 3,000 natural MIAs and a virtually infinite number of new-to-nature analogues.
    Type of Medium: Online Resource
    ISSN: 0028-0836 , 1476-4687
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    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
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  • 5
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 2017
    In:  Proceedings of the National Academy of Sciences Vol. 114, No. 11 ( 2017-03-14), p. 2964-2969
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 114, No. 11 ( 2017-03-14), p. 2964-2969
    Abstract: Previous studies have shown that receptor-interacting protein kinase 3 (RIP3) is involved in many important biological processes, including necroptosis, apoptosis, and inflammation. Here we show that RIP3 plays a critical role in regulating platelet functions and in vivo thrombosis and hemostasis. Tail bleeding times were significantly longer in RIP3 -knockout (RIP3 −/− ) mice compared with their wild-type (WT) littermates. In an in vivo model of arteriole thrombosis, mice lacking RIP3 exhibited prolonged occlusion times. WT mice repopulated with RIP3 −/− bone marrow-derived cells had longer occlusion times than RIP3 −/− mice repopulated with WT bone marrow-derived cells, suggesting a role for RIP3-deficient platelets in arterial thrombosis. Consistent with these findings, we observed that RIP3 was expressed in both human and mice platelets. Deletion of RIP3 in mouse platelets caused a marked defect in aggregation and attenuated dense granule secretion in response to low doses of thrombin or a thromboxane A 2 analog, U46619. Phosphorylation of Akt induced by U46619 or thrombin was diminished in RIP3 −/− platelets. Moreover, RIP3 interacted with Gα 13 . Platelet spreading on fibrinogen and clot retraction were impaired in the absence of RIP3. RIP3 inhibitor dose-dependently inhibited platelet aggregation in vitro and prevented arterial thrombus formation in vivo. These data demonstrate a role for RIP3 in promoting in vivo thrombosis and hemostasis by amplifying platelet activation. RIP3 may represent a novel promising therapeutic target for thrombotic diseases.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
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    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2017
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
    SSG: 12
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  • 6
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 2014
    In:  Proceedings of the National Academy of Sciences Vol. 111, No. 37 ( 2014-09-16), p. 13517-13522
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 111, No. 37 ( 2014-09-16), p. 13517-13522
    Abstract: Methicillin-resistant Staphylococcus aureus (MRSA) is the most frequent cause of hospital-acquired infection, which manifests as surgical site infections, bacteremia, and sepsis. Due to drug-resistance, prophylaxis of MRSA infection with antibiotics frequently fails or incites nosocomial diseases such as Clostridium difficile infection. Sortase A is a transpeptidase that anchors surface proteins in the envelope of S. aureus , and sortase mutants are unable to cause bacteremia or sepsis in mice. Here we used virtual screening and optimization of inhibitor structure to identify 3-(4-pyridinyl)-6-(2-sodiumsulfonatephenyl)[1,2,4]triazolo[3,4-b] [1,3,4]thiadiazole and related compounds, which block sortase activity in vitro and in vivo. Sortase inhibitors do not affect in vitro staphylococcal growth yet protect mice against lethal S. aureus bacteremia. Thus, sortase inhibitors may be useful as antiinfective therapy to prevent hospital-acquired S. aureus infection in high-risk patients without the side effects of antibiotics.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
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    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2014
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
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  • 7
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 2003
    In:  Proceedings of the National Academy of Sciences Vol. 100, No. 21 ( 2003-10-14), p. 12283-12288
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 100, No. 21 ( 2003-10-14), p. 12283-12288
    Abstract: Strabismus has been known to have a significant genetic component, but the mode of inheritance and the identity of the relevant genes have been enigmatic. This paper reports linkage analysis of nonsyndromic strabismus. The principal results of this study are: ( i ) the demonstrated feasibility of identifying and recruiting large families in which multiple members have (or had) strabismus; ( ii ) the linkage in one large family of a presumptive strabismus susceptibility locus to 7p22.1 with a multipoint logarithm of odds score of 4.51 under a model of recessive inheritance; and ( iii ) the failure to observe significant linkage to 7p in six other multiplex families, consistent with genetic heterogeneity among families. These findings suggest that it will be possible to localize and ultimately identify strabismus susceptibility genes by linkage analysis and mutation screening of candidate genes.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
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    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2003
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
    SSG: 11
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  • 8
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 99, No. 22 ( 2002-10-29), p. 14398-14403
    Abstract: The interaction of activated Ras with Raf initiates signaling cascades that contribute to a significant percentage of human tumors, suggesting that agents that specifically disrupt this interaction might have desirable chemotherapeutic properties. We used a subtractive forward two-hybrid approach to identify small molecule compounds that block the interaction of Ras with Raf. These compounds (MCP1 and its derivatives, 53 and 110) reduced serum-induced transcriptional activation of serum response element as well as Ras-induced transcription by way of the AP-1 site. They also inhibited Ras-induced Raf-1 activation in human embryonic kidney 293 cells, Raf-1 and mitogen-activated protein kinase kinase 1 activities in HT1080 fibrosarcoma cells, and epidermal growth factor-induced Raf-1 activation in A549 lung carcinoma cells. The MCP compounds caused reversion of ras -transformed phenotypes including morphology, in vitro invasiveness, and anchorage-independent growth of HT1080 cells. Decreased level of matrix metalloproteinases was also observed. Further characterization showed that MCP compounds restore actin stress fibers and cause flat reversion in NIH 3T3 cells transformed with H-Ras (V12) but not in NIH 3T3 cells transformed with constitutively active Raf-1 (RafΔN). Finally, we show that MCP compounds inhibit anchorage-independent growth of A549 and PANC-1 cells harboring K- ras mutation. Furthermore, MCP110 caused G 1 enrichment of A549 cells with the decrease of cyclin D level. These results highlight potent and specific effects of MCP compounds on cancer cells with intrinsic Ras activation.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
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    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2002
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  • 9
    Online Resource
    Online Resource
    Proceedings of the National Academy of Sciences ; 2021
    In:  Proceedings of the National Academy of Sciences Vol. 118, No. 8 ( 2021-02-23)
    In: Proceedings of the National Academy of Sciences, Proceedings of the National Academy of Sciences, Vol. 118, No. 8 ( 2021-02-23)
    Abstract: Secondary organic aerosol (SOA) produced by atmospheric oxidation of primary emitted precursors is a major contributor to fine particulate matter (PM 2.5 ) air pollution worldwide. Observations during winter haze pollution episodes in urban China show that most of this SOA originates from fossil-fuel combustion but the chemical mechanisms involved are unclear. Here we report field observations in a Beijing winter haze event that reveal fast aqueous-phase conversion of fossil-fuel primary organic aerosol (POA) to SOA at high relative humidity. Analyses of aerosol mass spectra and elemental ratios indicate that ring-breaking oxidation of POA aromatic species, leading to functionalization as carbonyls and carboxylic acids, may serve as the dominant mechanism for this SOA formation. A POA origin for SOA could explain why SOA has been decreasing over the 2013–2018 period in response to POA emission controls even as emissions of volatile organic compounds (VOCs) have remained flat.
    Type of Medium: Online Resource
    ISSN: 0027-8424 , 1091-6490
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    Language: English
    Publisher: Proceedings of the National Academy of Sciences
    Publication Date: 2021
    detail.hit.zdb_id: 209104-5
    detail.hit.zdb_id: 1461794-8
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  • 10
    Online Resource
    Online Resource
    American Association for the Advancement of Science (AAAS) ; 2021
    In:  Science Vol. 371, No. 6536 ( 2021-03-26), p. 1374-1378
    In: Science, American Association for the Advancement of Science (AAAS), Vol. 371, No. 6536 ( 2021-03-26), p. 1374-1378
    Abstract: The COVID-19 pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continually poses serious threats to global public health. The main protease (M pro ) of SARS-CoV-2 plays a central role in viral replication. We designed and synthesized 32 new bicycloproline-containing M pro inhibitors derived from either boceprevir or telaprevir, both of which are approved antivirals. All compounds inhibited SARS-CoV-2 M pro activity in vitro, with 50% inhibitory concentration values ranging from 7.6 to 748.5 nM. The cocrystal structure of M pro in complex with MI-23, one of the most potent compounds, revealed its interaction mode. Two compounds (MI-09 and MI-30) showed excellent antiviral activity in cell-based assays. In a transgenic mouse model of SARS-CoV-2 infection, oral or intraperitoneal treatment with MI-09 or MI-30 significantly reduced lung viral loads and lung lesions. Both also displayed good pharmacokinetic properties and safety in rats.
    Type of Medium: Online Resource
    ISSN: 0036-8075 , 1095-9203
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    Language: English
    Publisher: American Association for the Advancement of Science (AAAS)
    Publication Date: 2021
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    detail.hit.zdb_id: 2066996-3
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    SSG: 11
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