22 research outputs found

    Applying TADF Emitters in Bioimaging and Sensing—A Novel Approach Using Liposomes for Encapsulation and Cellular Uptake

    Get PDF
    A new method for facilitating the delivery, uptake and intracellular localisation of thermally activated delayed fluorescence (TADF) complexes was developed. First, confinement of TADF complexes in liposomes was demonstrated, which were subsequently used as the delivery vehicle for cellular uptake. Confocal fluorescence microscopy showed TADF complexes subsequently localise in the cytoplasm of HepG2 cells. The procedures developed in this work included the removal of molecular oxygen in the liposome preparation without disrupting the liposome structures. Time-resolved fluorescence microscopy (point scanning) showed initial prompt fluorescence followed by a weak, but detectable, delayed fluorescence component for liposomal TADF internalised in HepG2 cells. By demonstrating that it is possible to deliver un-functionalised and/or unshielded TADF complexes, a sensing function for TADFs, such as molecular oxygen, can be envisaged

    Aggregation induced emission of a new naphthyridine-ethynyl-gold(I) complex as a potential tool for sensing guanosine nucleotides in aqueous media

    Get PDF
    A new organometallic alkynyl-gold(I) complex, capable of exhibiting Aggregation Induced Emission was designed and synthesized. The linear complex structure possesses a central Au(I) atom, bearing two axial ligands: (1) 1,3,5-Triaza-7-phosphaadamantane; and (2) 2- acetamido-7-ethynyl-1,8-naphthyridine. While the former accounts for its partial solubility in aqueous environment, the latter acts as a receptor unit for binding guanosine nucleotides and derivatives via multiple hydrogen bonding. At high concentrations, aggregation of the complex was observed by the formation of new absorption (λmax ~ 400 nm) and emission bands (550-700 nm). Formation of aggregates of ca. 60 nm diameter was confirmed with Small Angle X-Ray Scattering (SAXS). Disruption of the aggregates in the presence of guanosine derivatives resulted in a ratiometric signal with apparent association constants in the order of 105 M-1 and high sensitivity (around 63% signal change) which are, to the best of our knowledge, in line with the highest recorded for nucleotide sensing based on hydrogen bonding that are capable of working in water. Computational studies indicate the presence of additional hydrogen bonding interactions that account for the strong binding of the Au(I) complex to phosphorylated Guanosine nucleotides

    Multifunctionality of the [C2mim][Ln(fod)4] series (Ln = Nd-Tm except Pm):magnetic, luminescent and thermochemical studies

    Get PDF
    A series of nine tetrakis lanthanide β-diketonate complexes of the type [C2mim][Ln(fod)4] (C2mim = 1-ethyl-3-methylimidazolium, fod = 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionate) were prepared, with yields above 80%, and their thermochemical, photophysical and magnetic susceptibilities were evaluated. Thermochemical studies presented a rare and reversible conversion between two solid phases (polymorphism), characteristic of the [Ln(fod)4]− anion. Photophysical and magnetic studies revealed that Dy and Er presented the multifunctionality of being simultaneously SMMs and visible (Dy) or near infra-red (Er) emitters. The Nd, Ho and Tm analogues present characteristic emission bands in the NIR region (800–1200 nm), while Sm, Eu, Tb and Dy present emissions in the visible range. Magnetic susceptibility of Tb, Dy, Ho, Er and Tm salts were measured in the temperature range of 2–300 K, showing paramagnetic behaviour, although with different regimes, with AC susceptibility measurements, at different frequencies in the range of 10–10 000 Hz, providing evidence of slow magnetic relaxation processes for Gd, Dy and Er analogues with SMM behavior.publishe

    The contributions of molecular vibrations and higher triplet levels to the intersystem crossing mechanism in metal-free organic emitters.

    Get PDF
    Intense, simultaneous, room temperature phosphorescence (RTP) and thermally activated delayed fluorescence (TADF) is observed in a series of donor-acceptor-donor (D–A–D) molecules. This dual-luminescence is stronger in the “angular” isomers, compared to their “linear” regioisomers, which is consistent with an enhanced intersystem crossing (ISC) in the former. Herein, we demonstrate that the small energy gap between the triplet levels, T1-Tn, below the lowest singlet state, S1, in the “angular” regioisomers, enhances the coupling between S1 and T1 states and favors ISC and reverse ISC (rISC). This is consistent with a spin-vibronic mechanism. In the absence of this “triplet ladder”, due to the larger energy difference between T1 and Tn in the “linear” regioisomers, the ISC and rISC are not efficient. Remarkably the enhancement on the ISC rate in the “angular” regioisomers is accompanied by an increase on the rate of internal conversion (IC). These results highlight the contributions of higher triplet excited states and molecular vibronic coupling to harvest triplet states in organic compounds, and casts the TADF and RTP mechanisms into a common conceptual framework

    RoFnet – Reconfigurable Radio over Fiber Network Architecture Overview, Journal of Telecommunications and Information Technology, 2009, nr 1

    Get PDF
    This paper introduces the basic operational concepts of the RoFnet – reconfigurable radio over fiber network, which is a project supported by the Portuguese Foundation forScience and Technology. This project proposes an innovative radio over fiber optical access network architecture, which combines a low cost base station (BS) design, incorporating reflective semiconductor optical amplifiers, with fiber dispersion mitigation provided by optical single sideband modulation techniques. Optical wavelength division multiplexing (WDM) techniques are used to simplify the access network architecture allowing for different BSs to be fed by a common fiber. Different wavelength channels can be allocated to different BSs depending on user requirements. Additionally, in order to improve radio coverage within a cell, it is considered a sectorized antenna interface. The combination of subcarrier multiplexing with WDM, further simplifies the network architecture, by using a specific wavelength channel to feed an individual BS and different subcarriers to drive the individual antenna sectors within the BS

    The taxation of foreign experts with net salary agreements : An analysis about the application of Chapter 11, section 22 part 3 IL, Tax rollover and the Advances Method

    Get PDF
    I HFD 2014 ref 76 ändrar Högsta Förvaltningsdomstolen tidigare instansers domslut och fastställer hur beräkningen av bruttolönen ska göras för utländska arbetstagare med nettolöneavtal, vilka tillämpar 11 kap. 22 § 3 st. Inkomstskattelagen (1999:1229), IL. Vid ett nettolöneavtal kommer arbetstagaren och arbetsgivaren vanligtvis överens om att arbetsgivaren ska stå för arbetstagarens skatt. Eftersom IL utgår från en bruttolönebeskattning krävs att en gross-up görs från nettolönen till en bruttolön, vilket samtliga instanser är eniga om. Enligt HFD ska skattelättnaden på 25 procent som arbetstagaren erhåller enligt 11 kap. 22-23 §§ IL räknas bort, innan bedömning görs om lönen överstiger gränsbeloppet lagen anger. Följden i och med HFD:s dom blir att bruttolönen före hänsyn tagen till skattelättnad måste uppgå till ca 120 000 kr, vilket utgör ett nytt gränsbelopp för arbetstagare med nettolöneavtal. Denna beräkning behöver inte göras när arbetstagaren har ett bruttolöneavtal, utan i dessa fall kan bruttolönen direkt jämföras med gränsbeloppet på 89 000 kr. Varför domstolen gör denna bedömning är oklart, resonemanget till varför den kommer till det domslut den gör är inte utvecklat. Enligt oss kan resonemang föras om domstolen tyckte att nettolöneavtalen utnyttjar lagstiftningen på ett felaktigt sätt, då det är arbetsgivaren som vid nettolöneavtal påverkas när skattelättnad medges, och att en hårdare bedömning ska göras vid dessa typer av avtal. Varför skulle arbetstagare med bruttolöneavtal annars få fortsätta tillämpa basbeloppsregeln utan hänsyn tagen till skattelättnad? Det finns fortfarande flera fördelaktiga metoder utländska arbetstagare med nettolöneavtal kan tillämpa när deras lön inte når upp till gränsbeloppet. Tax rollover är en metod som behandlas i uppsatsen, vilken gör det möjligt att skjuta på beskattningen ett år och arbetstagare kan därigenom göra en nuvärdesvinst och dessutom komma ner i en lägre skiktgräns i vissa fall. En annan fördelaktig metod som kommer beröras är Förskottsmetoden, vilken innebär att Lag (1991:586) om särskild inkomstskatt för utomlands bosatta, SINK, kombineras med expertskattelättnaden i IL och resultatet blir en faktisk beskattning på 15 procent.In HFD 2014 ref. 76 the Supreme Administrative Court (HFD) changes earlier bodies’ verdict and determines how the calculation of the gross salary should be done for foreign workers with net payment agreement, according to Chapter 11, section 22 part 3 IL. Generally at a net salary agreement the employee and the employer agree that the employer will bear the worker’s tax. Since IL is based on gross taxation it is required that a gross-up is mad  from net salary to gross salary in which all parties agree. Thereafter, according to HFD, the deduction of tax credit obtained will be calculated in accordance to Chapter 11, sections 22-23 IL, before assessment is made if the salary exceeds the limit provided by law. The consequence of HFD’s ruling is that gross salary need to amount to about 120 000 SEK before tax benefits can be taken into account, which represents a new frontier amount for workers with net pay agreements. This calculation does not need to be made when the employee has a gross salary contract. In these cases the gross salary can be directly compared with the frontier value at 89 000. Why the court make this assessment is unclear and they do not further develop why they come to the judicial decision they make. Most likely, we consider the court found that the net salary agreements utilize the law in a wrong way, since it is the employer that is affected at a net salary agreement when tax benefits are allowed. Further, the Court may suggest that a stricter assessment should be made during these types of agreements. Why else would they let the gross salary agreements continue calculations without considering tax benefits? There are still several advantageous methods employees with net salary agreements that do not reach the limit can apply. One method used in this paper is ‘Tax rollover’ which makes it possible to postpone taxation for a year and can thus make a net present value gain and, in some cases, it can also lower the threshold for the taxation. Another advantageous method that will be discussed is the “Advances method” where SINK is combined with expert tax credit in IL and results in a tax rate of 15%

    Applying TADF Emitters in Bioimaging and Sensing—A Novel Approach Using Liposomes for Encapsulation and Cellular Uptake

    Get PDF
    A new method for facilitating the delivery, uptake and intracellular localisation of thermally activated delayed fluorescence (TADF) complexes was developed. First, confinement of TADF complexes in liposomes was demonstrated, which were subsequently used as the delivery vehicle for cellular uptake. Confocal fluorescence microscopy showed TADF complexes subsequently localise in the cytoplasm of HepG2 cells. The procedures developed in this work included the removal of molecular oxygen in the liposome preparation without disrupting the liposome structures. Time-resolved fluorescence microscopy (point scanning) showed initial prompt fluorescence followed by a weak, but detectable, delayed fluorescence component for liposomal TADF internalised in HepG2 cells. By demonstrating that it is possible to deliver un-functionalised and/or unshielded TADF complexes, a sensing function for TADFs, such as molecular oxygen, can be envisaged
    corecore