48 research outputs found

    "WDM-DPSK Detection by means of Frequency-Periodic Gaussian Filtering"

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    A single frequency-periodic narrow filter converts DPSK to intensity modulation in a high number of WDM channels. It also strongly enhances their tolerance to chromatic dispersion and is exploited in a 16x10 Gbit/s transmission over 240 km G.652 fibre with no chromatic dispersion compensation

    Organic Azides : Functional Molecules and Materials

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    The work presented in this thesis stems from the chemistry of the azido group, and more specifically from the unique reactivity of perfluorinated aromatic azides and how to use this reactivity to access new types of molecules to enable new applications in asymmetric synthesis and materials. In the first section of this thesis, a photoactivatable fluorescence probe is presented, where the non-luminescent azide was activated via a UV-light-promoted intramolecular N–H insertion reaction forming a fluorescence emitter. Furthermore, ciprofloxacin was reacted with perfluorinated aromatic azide (PFAA) and phenylacetaldehyde, to form a drug derivative with a propeller-shaped architecture. The drug derivatization enabled the self-aggregation of the molecules into nanoparticles and the consequent aggregation-induced fluorescence emission (AIE).  The second section of the thesis focuses on the development of a reaction between the photogenerated perfluorinated phenylnitrene and sulfoxides or sulfinamides to obtain sulfoximines and sulfonimidamides. One of these compounds, an enantiopure sulfonimidamide with an unprotected amino group, was employed as a novel chiral auxiliary for the synthesis of an enantioenriched amine via addition of Grignard reagents to the formed imines. In addition to the use as chiral auxiliary, the same sulfonimidamide containing a pyridine group was studied as an organogelator. The supramolecular aggregation led to the formation of the gel, which showed a microscopic chirality controlled by the stereocenter of the sulfur atom in the low-molecular weight gelator molecule.  The last section illustrates a general method for the reduction of aromatic and aliphatic azides. The reduction is catalyzed by a nickel boride (Ni-B) catalyst that is prepared in situ from a Ni(II) salt and sodium borohydride in methanol allowing catalyst loading as low as 0.5 mol%. Moreover, bacterial nanocellulose (BNC) was used as solid support for the Ni-B catalyst enabling easy recovery of the catalyst and recyclability.Arbetet som presenteras i denna avhandling hĂ€rrör frĂ„n reaktiviteten hos azidogruppen, som uppvisar en unik reaktivitet som inte Ă„terfinns i naturen vilket gör att azidgruppen kan anvĂ€ndas i bioortogonala reaktioner. I det första avsnittet av denna avhandling presenteras en molekyl som innehĂ„lleren azid-grupp som kan aktiveras med ljus för att avge fluorescens. Aziden Ă€r ej luminescerande, men vid belysning med UV-ljus initieras en intramolekylĂ€rreaktion och omvandlades följaktligen till en fluorescerande molekyl. I ett annat projekt, reagerades ciprofloxacin med perfluorerad aromatisk azid (PFAA) och fenylacetaldehyd för att bilda ett lĂ€kemedelsderivat med en propellerformad arkitektur. Derivatiseringen möjliggjorde en sjĂ€lvaggregation av molekylerna i nanopartiklar vilket ledde till en sĂ„ kallad aggregeringsinducerad fluorescensemission (AIE). I avhandlingens andra avsnitt beskrivs reaktionen mellan ljusgenererade perfluorerade fenylnitrener och sulfoxider eller sulfinamider för att syntetisera sulfoximiner och sulfonimidamider. En av de enantiomert rena sulfonimidamiderna med en oskyddad aminogrupp anvĂ€ndes som en ny kiral hjĂ€lpgrupp för syntesen av en enantiomert ren amin. Vidare anvĂ€ndes en av de kirala sulfonimidamiderna som en organogelator. Den supramolekylĂ€ra aggregeringen som ledde till bildandet av gelen, visade en mikroskopisk kiralitet styrd av stereorienteringen av det kirala centret pĂ„ svavelatomen i gelatormolekylen. I det sista avsnittet presenteras en metod för reduktion av aromatiska och alifatiska azider. Reduktionen katalyseras av nickelborid framstĂ€lld frĂ„n ettNi(II)-salt och natriumborhydrid i metanol och fungerade lĂ„g mĂ€ngd katalysator(0,5 mol%). Dessutom anvĂ€ndes bakteriell nanocellulosa (BNC) som fast stödför Ni-B-katalysatorn vilket möjliggjorde enkel Ă„tervinning av katalysatorn och dess Ă„tervinningsbarhet.QC 20210906</p

    Organic Azides : Functional Molecules and Materials

    No full text
    The work presented in this thesis stems from the chemistry of the azido group, and more specifically from the unique reactivity of perfluorinated aromatic azides and how to use this reactivity to access new types of molecules to enable new applications in asymmetric synthesis and materials. In the first section of this thesis, a photoactivatable fluorescence probe is presented, where the non-luminescent azide was activated via a UV-light-promoted intramolecular N–H insertion reaction forming a fluorescence emitter. Furthermore, ciprofloxacin was reacted with perfluorinated aromatic azide (PFAA) and phenylacetaldehyde, to form a drug derivative with a propeller-shaped architecture. The drug derivatization enabled the self-aggregation of the molecules into nanoparticles and the consequent aggregation-induced fluorescence emission (AIE).  The second section of the thesis focuses on the development of a reaction between the photogenerated perfluorinated phenylnitrene and sulfoxides or sulfinamides to obtain sulfoximines and sulfonimidamides. One of these compounds, an enantiopure sulfonimidamide with an unprotected amino group, was employed as a novel chiral auxiliary for the synthesis of an enantioenriched amine via addition of Grignard reagents to the formed imines. In addition to the use as chiral auxiliary, the same sulfonimidamide containing a pyridine group was studied as an organogelator. The supramolecular aggregation led to the formation of the gel, which showed a microscopic chirality controlled by the stereocenter of the sulfur atom in the low-molecular weight gelator molecule.  The last section illustrates a general method for the reduction of aromatic and aliphatic azides. The reduction is catalyzed by a nickel boride (Ni-B) catalyst that is prepared in situ from a Ni(II) salt and sodium borohydride in methanol allowing catalyst loading as low as 0.5 mol%. Moreover, bacterial nanocellulose (BNC) was used as solid support for the Ni-B catalyst enabling easy recovery of the catalyst and recyclability.Arbetet som presenteras i denna avhandling hĂ€rrör frĂ„n reaktiviteten hos azidogruppen, som uppvisar en unik reaktivitet som inte Ă„terfinns i naturen vilket gör att azidgruppen kan anvĂ€ndas i bioortogonala reaktioner. I det första avsnittet av denna avhandling presenteras en molekyl som innehĂ„lleren azid-grupp som kan aktiveras med ljus för att avge fluorescens. Aziden Ă€r ej luminescerande, men vid belysning med UV-ljus initieras en intramolekylĂ€rreaktion och omvandlades följaktligen till en fluorescerande molekyl. I ett annat projekt, reagerades ciprofloxacin med perfluorerad aromatisk azid (PFAA) och fenylacetaldehyd för att bilda ett lĂ€kemedelsderivat med en propellerformad arkitektur. Derivatiseringen möjliggjorde en sjĂ€lvaggregation av molekylerna i nanopartiklar vilket ledde till en sĂ„ kallad aggregeringsinducerad fluorescensemission (AIE). I avhandlingens andra avsnitt beskrivs reaktionen mellan ljusgenererade perfluorerade fenylnitrener och sulfoxider eller sulfinamider för att syntetisera sulfoximiner och sulfonimidamider. En av de enantiomert rena sulfonimidamiderna med en oskyddad aminogrupp anvĂ€ndes som en ny kiral hjĂ€lpgrupp för syntesen av en enantiomert ren amin. Vidare anvĂ€ndes en av de kirala sulfonimidamiderna som en organogelator. Den supramolekylĂ€ra aggregeringen som ledde till bildandet av gelen, visade en mikroskopisk kiralitet styrd av stereorienteringen av det kirala centret pĂ„ svavelatomen i gelatormolekylen. I det sista avsnittet presenteras en metod för reduktion av aromatiska och alifatiska azider. Reduktionen katalyseras av nickelborid framstĂ€lld frĂ„n ettNi(II)-salt och natriumborhydrid i metanol och fungerade lĂ„g mĂ€ngd katalysator(0,5 mol%). Dessutom anvĂ€ndes bakteriell nanocellulosa (BNC) som fast stödför Ni-B-katalysatorn vilket möjliggjorde enkel Ă„tervinning av katalysatorn och dess Ă„tervinningsbarhet.QC 20210906</p

    Gravity currents produced by lock-exchanges: experiments and simulations with a two layer shallow-water model with entrainment

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    "\"This paper presents the investigation of gravity currents by both laboratory experiments and a mathematical model. Eleven lock-exchange experiments, in which lock position, the initial current height, and density varied, were carried out to test the model validity and to compare laboratory results with previous expressions found in the literature. A two-layer shallow-water model was used to simulate all the runs. This model is new if compared with previous shallow-water models used to simulate gravity currents, because it accounts for both the entrainment and the free surface. A modified Turner’s formula is used to model the entrainment between the two fluids. The developed shallow-water models with and without entrainment are also compared, showing a better agreement when mixing is accounted for. Also, the effect of the free surface is shown by comparing the developed two-layer shallow-water model with a free surface and two different single-layer models with a rigid lid approximation. Laboratory experiments and model simulations, accounting for both the entrainment and the free surface, are in good agreement. Front velocities, measured during the slumping phase, were compared with both predicted ones and previous expressions found in the literature, showing in most of the cases better result when the developed model is used \"

    Semiconductor-Amplified WDM-POLSK Systems

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    We exploit the constant envelope of POLSK format to transmit 8x10 Gb/s WDM signals using SOAbased amplification. In short and medium reach systems encompassing NZDFs, amplifier span values higher than 115 km are demonstrate

    Simultaneous Multi-Wavelength Conversion by Double Stage XGM in SOAs

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    We obtain multi-wavelength conversion of an input 10 Gbit/s NRZ-signal to eight 200 GHz-spaced output channels using double stage XGM in SOAs. The obtained multicast signals show a moderate OSNR-penalty
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