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1.
Maria?Teresa?Neves-Petersen S?ren?Klitgaard Esben?Skovsen Steffen?B.?Petersen Kristoffer?T?mmeraas Khadija?Schwach-Abdellaoui 《Journal of fluorescence》2010,20(2):483-492
Modification of hyaluronic acid (HA) with aryl succinic anhydrides results in new biomedical properties of HA as compared
to non-modified HA, such as more efficient skin penetration, stronger binding to the skin, and the ability to blend with hydrophobic
materials. In the present study, hyaluronic acid has been derivatised with the anhydride form of phenyl succinic acid (PheSA).
The fluorescence of PheSA was efficiently quenched by the HA matrix. HA also acted as a singlet oxygen scavenger. Fluorescence
lifetime(s) of PheSA in solution and when attached to the HA matrix has been monitored with ps resolved streak camera technology.
Structural and fluorescence properties changes induced on HA-PheSA due to the presence of singlet oxygen were monitored using
static light scattering (SLS), steady state fluorescence and ps time resolved fluorescence studies. SLS studies provided insight
into the depolymerisation kinetics of PheSA derivatised HA matrix in the presence of singlet oxygen. Time resolved fluorescence
studies grave insight into the dynamics of the reaction mechanisms induced on HA-PheSA by singlet oxygen. These studies provided
insight into the medical relevance of PheSA derivatised HA: its capacity of scavenging singlet oxygen and of quenching PheSA
fluorescence. These studies revealed that HA-PheSA is a strong quencher of electronic excited state PheSA and acts as a scavenger
of singlet oxygen, thus medical applications of this derivatised form of HA may protect tissues and organs, such as skin,
against reactive oxygen species damage. 相似文献
2.
Tommi Kaplas Kari Laitinen Tuula Moilanen Yrj? Tolonen Kristoffer Albrecht Raimo Silvennoinen 《Optical Review》2010,17(3):252-256
Traditional Japanese woodblock printing is a centuries old art form. This time-honoured form of art is at risk of extinction as a consequence of the increasing lack of availability of wild cherry trees, which are a traditionally used woodblock material. Solutions for this material problem have been investigated for several years, but none of the tested materials has been sufficient when compared with the watercolour print quality imprinted by wild cherry woodblocks. To contribute to overcoming this material problem, we have investigated the physical properties of heat-treated woodblock materials made from different wood species. The International Commission on Illumination (CIE) tristimulus values, the CIELAB coordinates, the total reflectance, and the gloss, as well as, the water contact angle from the woodblock surface is observed to have a strong relation to the surface treatment of a woodblock. The surface treatment of a woodblock, in turn, relates to its water delivery, which is the basis for watercolour printing. 相似文献
3.
Ana A. C. Pacheco Arnaldo F. da Silva Filho Kristoffer Kortsen Magnus W. D. Hanson-Heine Vincenzo Taresco Jonathan D. Hirst Muriel Lansalot Franck D'Agosto Steven M. Howdle 《Chemical science》2021,12(3):1016
Reversible addition–fragmentation chain transfer (RAFT) dispersion polymerisation of methyl methacrylate (MMA) is performed in supercritical carbon dioxide (scCO2) with 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (DDMAT) present as chain transfer agent (CTA) and surprisingly shows good control over PMMA molecular weight. Kinetic studies of the polymerisation in scCO2 also confirm these data. By contrast, only poor control of MMA polymerisation is obtained in toluene solution, as would be expected for this CTA which is better suited for acrylates. In this regard, we select a range of CTAs and use them to determine the parameters that must be considered for good control in dispersion polymerisation in scCO2. A thorough investigation of the nucleation stage during the dispersion polymerisation reveals an unexpected “in situ two-stage” mechanism that strongly determines how the CTA works. Finally, using a novel computational solvation model, we identify a correlation between polymerisation control and degree of solubility of the CTAs. All of this ultimately gives rise to a simple, elegant and counterintuitive guideline to select the best CTA for RAFT dispersion polymerisation in scCO2.RAFT dispersion polymerisation of methyl methacrylate is performed in scCO2 with 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid (DDMAT) present as chain transfer agent (CTA) and surprisingly shows good control over PMMA molecular weight. 相似文献
4.
Tomasz Maciej Stepniewski Arturo Mancini Richard gren Mariona Torrens-Fontanals Meriem Semache Michel Bouvier Kristoffer Sahlholm Billy Breton Jana Selent 《Chemical science》2021,12(33):10990
Brain functions rely on neurotransmitters that mediate communication between billions of neurons. Disruption of this communication can result in a plethora of psychiatric and neurological disorders. In this work, we combine molecular dynamics simulations, live-cell biosensor and electrophysiological assays to investigate the action of the neurotransmitter dopamine at the dopaminergic D2 receptor (D2R). The study of dopamine and closely related chemical probes reveals how neurotransmitter binding translates into the activation of distinct subsets of D2R effectors (i.e.: Gi2, GoB, Gz and β-arrestin 2). Ligand interactions with key residues in TM5 (S5.42) and TM6 (H6.55) in the D2R binding pocket yield a dopamine-like coupling signature, whereas exclusive TM5 interaction is typically linked to preferential G protein coupling (in particular GoB) over β-arrestin. Further experiments for serotonin receptors indicate that the reported molecular mechanism is shared by other monoaminergic neurotransmitter receptors. Ultimately, our study highlights how sequence variation in position 6.55 is used by nature to fine-tune β-arrestin recruitment and in turn receptor signaling and internalization of neurotransmitter receptors.Neurotransmitter contacts within the receptor binding site differentially contribute to the overall functional response: transmembrane helix (TM) 5 contacts promote G protein coupling whereas concerted TM5–TM6 contacts enhance β-arrestin recruitment. 相似文献
5.
Emtenäs H Ahlin K Pinkner JS Hultgren SJ Almqvist F 《Journal of combinatorial chemistry》2002,4(6):630-639
A new method for the solid-phase synthesis of enantiomerically enriched highly substituted ring-fused 2-pyridinones 13 has been developed. The synthesis mediates introduction of substituents at two positions in the 2-pyridinone ring in a diverse manner and is suitable for parallel synthesis. (19)F NMR spectroscopy was used as a tool to monitor each of the five steps in the reaction sequence. The optimized conditions thus obtained were then used to prepare a library of 20 2-pyridinones with high yields. The library members were chosen from a statistical multivariate design to ensure diversity and reliable data for structure-activity relationships. Screening of the library against the bacterial periplasmic chaperone PapD was performed using surface plasmon resonance. Three new 2-pyridinones with a higher affinity for the chaperone PapD than the previous best 13[10,1] were found, and important structural features could be deduced. 相似文献
6.
Petr tpnek Terry L. Morkved Frank S. Bates Timothy P. Lodge Kristoffer Almdal 《Macromolecular Symposia》2000,149(1):107-112
We have used dynamic light scattering to study the dynamics of ternary polymer blends consisting of poly(dimethylsiloxane) (PDMS) and poly(ethylethylene) (PEE) homopolymers and a PDMS‐PEE diblock copolymer nearly symmetric in composition. The intensity autocorrelation functions for the binary blend are single‐exponential, and the associated correlation length ξ scales with reduced temperature ϵ in accordance with the Ising universality class (i.e., ξ ∼ ϵ−ν, with ν = 0.63). An addition of copolymer depresses the critical temperature, but also increases the magnitude of ν. For compositions within the microemulsion channel, ξ exhibits a distinct maximum with decreasing temperature, near the Lifshitz line obtained from the static structure factor. For a particular composition, there is a “re‐entrant” microemulsion, as the system passes into and then out of the phase‐separated region upon cooling. 相似文献
7.
Dr. Denis Leshchev Dr. Andrew J. S. Valentine Dr. Pyosang Kim Dr. Alexis W. Mills Dr. Subhangi Roy Dr. Arnab Chakraborty Dr. Elisa Biasin Prof. Kristoffer Haldrup Dr. Darren J. Hsu Dr. Matthew S. Kirschner Dr. Dolev Rimmerman Dr. Matthieu Chollet Dr. J. Michael Glownia Dr. Tim B. van Driel Prof. Felix N. Castellano Prof. Xiaosong Li Prof. Lin X. Chen 《Angewandte Chemie (International ed. in English)》2023,62(28):e202304615
Photoexcited molecular trajectories on potential energy surfaces (PESs) prior to thermalization are intimately connected to the photochemical reaction outcome. The excited-state trajectories of a diplatinum complex featuring photo-activated metal–metal σ-bond formation and associated Pt−Pt stretching motions were detected in real time using femtosecond wide-angle X-ray solution scattering. The observed motions correspond well with coherent vibrational wavepacket motions detected by femtosecond optical transient absorption. Two key coordinates for intersystem crossing have been identified, the Pt−Pt bond length and the orientation of the ligands coordinated with the platinum centers, along which the excited-state trajectories can be projected onto the calculated PESs of the excited states. This investigation has gleaned novel insight into electronic transitions occurring on the time scales of vibrational motions measured in real time, revealing ultrafast nonadiabatic or non-equilibrium processes along excited-state trajectories involving multiple excited-state PESs. 相似文献
8.
9.
Kristoffer Laursen Søren Søndergaard Frederiksen Casper Leuenhagen Rasmus Bro 《Journal of chromatography. A》2010,1217(42):6503-6510
It is common practice in chromatographic purity analysis of pharmaceutical manufacturing processes to assess the quality of peak integration combined by visual investigation of the chromatogram. This traditional method of visual chromatographic comparison is simple, but is very subjective, laborious and seldom very quantitative. For high-purity drugs it would be particularly difficult to detect the occurrence of an unknown impurity co-eluting with the target compound, which is present in excess compared to any impurity. We hypothesize that this can be achieved through Multivariate Statistical Process Control (MSPC) based on principal component analysis (PCA) modeling. In order to obtain the lowest detection limit, different chromatographic data preprocessing methods such as time alignment, baseline correction and scaling are applied. Historical high performance liquid chromatography (HPLC) chromatograms from a biopharmaceutical in-process analysis are used to build a normal operation condition (NOC) PCA model. Chromatograms added simulated 0.1% impurities with varied resolutions are exposed to the NOC model and monitored with MSPC charts. This study demonstrates that MSPC based on PCA applied on chromatographic purity analysis is a powerful tool for monitoring subtle changes in the chromatographic pattern, providing clear diagnostics of subtly deviating chromatograms. The procedure described in this study can be implemented and operated as the HPLC analysis runs according to the process analytical technology (PAT) concept aiming for real-time release. 相似文献
10.
Kristoffer Haldrup Dr. Morten Christensen Marco Cammarata Dr. Qingyu Kong Dr. Michael Wulff Prof. Simon O. Mariager Klaus Bechgaard Prof. Robert Feidenhans'l Prof. Niels Harrit Prof. Martin M. Nielsen Prof. 《Angewandte Chemie (International ed. in English)》2009,48(23):4180-4184
Molecular movies : Time‐resolved X‐ray scattering provides direct structural information on an electronically excited complex while it is formed in the bimolecular reaction between excited octahydrogen[tetrakis‐μ‐diphosphito‐1κP:2κP′‐diplatinate](4‐) (PtPOP*) and thallium ions. In the exciplex one thallium(I) and two platinum(II) ions are found to be collinear.