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IPG Photonics

About: IPG Photonics is a based out in . It is known for research contribution in the topics: Laser & Fiber laser. The organization has 903 authors who have published 1241 publications receiving 63339 citations.


Papers
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Journal ArticleDOI
20 Jan 2019
TL;DR: In this article, a few-cycle Cr2+:ZnS driving source was used to produce super-octave mid-IR electromagnetic transients via optical rectification (or intra-pulse difference frequency generation, IDFG).
Abstract: Femtosecond laser sources and optical frequency combs in the molecular fingerprint region of the electromagnetic spectrum are crucial for a plethora of applications in natural and life sciences. Here we introduce Cr2+-based lasers as a convenient means for producing super-octave mid-IR electromagnetic transients via optical rectification (or intra-pulse difference frequency generation, IDFG). We demonstrate that a relatively long, 2.5 μm, central wavelength of a few-cycle Cr2+:ZnS driving source (20 fs pulse duration, 6 W average power, 78 MHz repetition rate) enabled the use of highly nonlinear ZnGeP2 crystal for IDFG with exceptionally high conversion efficiency (>3%) and output power of 0.15 W, with the spectral span of 5.8–12.5 μm. Even broader spectrum was achieved in GaSe crystal: 4.3–16.6 μm for type I and 5.8–17.6 μm for type II phase matching. The results highlight the potential of this architecture for ultrafast spectroscopy and generation of broadband frequency combs in the longwave infrared.

99 citations

Journal ArticleDOI
TL;DR: In this paper, the authors studied carbon, water, sulphur and chlorine contents in melt and fluid inclusions trapped in olivines from diverse feeding systems of Piton de la Fournaise volcano (Reunion Island, Indian Ocean).

98 citations

Journal ArticleDOI
TL;DR: The findings point out the Cr(VI) immobilization mechanisms of SRB; suggesting that SRB are highly important in metal biogeochemistry and environmental significance.
Abstract: Toxic heavy metals constitute a worldwide environmental pollution problem. Bioremediation technologies represent efficient alternatives to the classic cleaning-up of contaminated soil and ground water. Most toxic heavy metals such as chromium are less soluble and toxic when reduced than when oxidized. Sulfate-reducing bacteria (SRB) are able to reduce heavy metals by a chemical reduction via the production of H2S and by a direct enzymatic process involving hydrogenases and c3 cytochromes. We have previously reported the effects of chromate [Cr(VI)] on SRB bioenergetic metabolism and the molecular mechanism of the metal reduction by polyhemic cytochromes. In the current work, we pinpoint the bacteria–metal interactions using Desulfovibrio vulgaris strain Hildenborough as a model. The bacteria were grown in the presence of high Cr(VI) concentration, where they accumulated precipitates of a reduced form of chromium, trivalent chromium [Cr(III)], on their cell surfaces. Moreover, the inner and outer membranes exhibited precipitates that shared the spectroscopic signature of trivalent chromium. This subcellular localization is consistent with enzymatic metal reduction by cytochromes and hydrogenases. Regarding environmental significance, our findings point out the Cr(VI) immobilization mechanisms of SRB; suggesting that SRB are highly important in metal biogeochemistry.

98 citations

Journal ArticleDOI
TL;DR: In this paper, the authors studied the properties of magnetosomes at several steps of maturity and found that the morphology of mature magnetosome is not exclusively determined by vectorial regulation at the organic boundaries or by molecular interaction with the magnetosOME membrane, but also by the rates of Fe uptake, which suggests that the expression of different faces is favored for different growth conditions.
Abstract: Magnetotactic bacteria are known to mediate the formation of intracellular magnetic nanoparticles in organelles called magnetosomes. These magnetite crystals are formed through a process called biologically controlled mineralization, in which the microorganisms exert a strict control over the formation and development of the mineral phase. By inducing magnetite nucleation and growth in resting, Fe-starved cells of Magnetospirillum gryphiswaldense, we have followed the dynamics of magnetosome development. By studying the properties of the crystals at several steps of maturity, we observed that freshly induced particles lacked a well-defined morphology. More surprisingly, although the mean particle size of mature magnetosomes is similar to that of magnetosomes formed by constantly growing and Fe-supplemented bacteria, we found that other physical properties such as crystal-size distribution, aspect ratio, and morphology significantly differ. Correlating these results with measurements of Fe uptake rates, we suggest that the expression of different faces is favored for different growth conditions. These results imply that the biological control over magnetite biomineralization by magnetotactic bacteria can be disturbed by environmental parameters. Specifically, the morphology of magnetite crystals is not exclusively determined by biological intervention through vectorial regulation at the organic boundaries or by molecular interaction with the magnetosome membrane, but also by the rates of Fe uptake. This insight may contribute to better define biomarkers and to an improved understanding of biomineralizing systems.

98 citations

Journal ArticleDOI
TL;DR: In this article, a new approach based on the S-to-P and the P-toS wave conversions is proposed, enabling the precise determination of the seismic velocities.
Abstract: SUMMARY Beneath the Tibet plateau, the deficit of crustal thickening with respect to what is expected from the plate tectonic constraints is thought to be absorbed either by lateral extrusion or by vertical rock-mass transfer. To nourish the unsettled debate of the relative importance of these two processes, we propose a new approach, based on the S-to-P and the P-to-S wave conversions, enabling the precise determination of the seismic velocities. The weighted amplitudes of the direct conversion and of reverberations are stacked at their predicted arrival times for various values of layer thickness and vP/vS ratio separately for two sets of P- and S-receiver functions. For each set of receiver functions, coherent stack gives the vP/ vS ratio and thickness for the considered layer (the grid search stacking method). The values of vP/vS ratio and layer thickness are functions of the velocity used for stacking the set of receiver functions, but using the P- and S-receiver functions allows us to solve this indetermination and to find the effective parameters of the layer: velocity vS, vP/ vS ratio and thickness. We use a bootstrap resampling of the receiver function data sets to estimate the parameters uncertainties. For the Southern Lhasa Block, the migrated sections of both P- and S-receiver functions (Hi-CLIMB experiment data) show a layer in the lower crust that may be related to the lower Indian crust underplated beneath Tibet. With the grid search stacking method, high shear wave velocities (vS ∼ 4.73 km s –1 ) and low vP/vS ratios (∼1.69) are detected in this layer. Such values are typical for high-grade eclogites, and the low vP/vS ratio precludes the confusion with mafic granulites. There is no evidence for partial eclogitization near and south of the Yarlung–Tsangpo Suture, and the about 19 km thick eclogitic layer extends northwards only to about the middle of the Lhasa terrane.

97 citations


Authors

Showing all 903 results

NameH-indexPapersCitations
Claude J. Allègre10632735092
Paul Tapponnier9929442855
Francesco Mauri8535269332
Barbara Romanowicz6728414950
Geoffrey C. P. King6415717177
Yi-Gang Xu6427114292
Jérôme Gaillardet6319914878
François Guyot6129212444
Georges Calas6026610901
Ari P. Seitsonen5921245684
Michele Lazzeri5814057079
Bernard Bourdon581189962
Gianreto Manatschal5620010063
Nikolai M. Shapiro5615415508
Guillaume Morin551567218
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202121
202025
201936
201839
201730
201652