Daria Larowska  Dr. Aleksandra Wojcik  Dr. Marta Mazurkiewicz-Pawlicka  Dr. Artur Malolepszy  Dr. Leszek Stobiński  Prof. Bronislaw Marciniak  Dr. Anna Lewandowska-Andralojc 《Chemphyschem》2019,20(8):1054-1066

Non-covalent nanohybrids composed of cationic 5,10,15,20-tetra(4-trimethylammoniophenyl)porphyrin tetra(p-toluenesulfonate) (TMAP) and the graphene oxide sheets were prepared under two pH values (6.2 vs. 1.8). The TMAP molecule was positively charged, regardless of the pH value during preparation. However, protonation of the imino nitrogens increased the overall charge of the porphyrin molecule from +4 to +6 (TMAP⁴⁺ and TMAP⁶⁺). It was found that at acidic pH, interaction of TMAP⁶⁺ with GO was largely suppressed. On the other hand, results of FTIR, Raman spectroscopy, thermogravimetric analysis, atomic force microscopy (AFM) and elemental analysis confirmed effective non-covalent functionalization of graphene oxide with cationic porphyrin at pH 6.2. The TMAP⁴⁺-GO hybrids exhibited well defined structure with a monolayer of TMAP⁴⁺ on the GO sheets as confirmed by AFM. Formation of the ground-state TMAP⁴⁺-GO complex in solution was monitored by the red-shift of the porphyrin Soret absorption band. This ground-state interaction between TMAP⁴⁺ and GO is responsible for the static quenching of the porphyrin emission. Fluorescence was not detected for the nanohybrid which indicated that a very fast deactivation process had to take place. Ultrafast time-resolved transient absorption spectroscopy clearly demonstrated the occurrence of electron transfer from the photoexcited TMAP⁴⁺ singlet state to GO sheets, as proven by the formation of a porphyrin radical cation.  相似文献   

    

Carmela Maria Montone  Michela Antonelli  Anna Laura Capriotti  Chiara Cavaliere  Giorgia La Barbera  Susy Piovesana  Aldo Lagan 《Journal of separation science》2019,42(10):1938-1947

An analytical method for determining seleno‐methionine, methyl‐seleno‐cysteine, and seleno‐cystine in wheat bran was developed and validated. Four different extraction procedures were evaluated to simultaneously extract endogenous free and conjugated seleno‐amino acids in wheat bran in order to select the best extraction protocol in terms of seleno amino acid quantitation. The extracted samples were subjected to a clean‐up by a reversed phase/strong cation exchange solid‐phase extraction and analyzed by chiral hydrophilic interaction liquid chromatography‐tandem mass spectrometry. The optimized extraction protocol was employed to validate the methodology. Process efficiency ranged from 58 to 112% and trueness from 73 to 98%. Limit of detection and limit of quantification were lower than 1 ng/g. Four wheat bran samples were analyzed for both total Se and single seleno‐amino acids determination. The results showed that Se‐ seleno‐methyl‐l selenocysteine was the major seleno‐amino acid in wheat bran while seleno‐methionine and seleno‐cysteine were both minor species.  相似文献   

    

Valentina Laghezza Masci  Anna‐Rita Taddei  Thomas Courant  Ozgül Tezgel  Fabrice Navarro  Franco Giorgi  Denis Mariolle  Anna‐Maria Fausto  Isabelle Texier 《Macromolecular bioscience》2019,19(5)

Curcumin‐loaded collagen cryostructurates have been devised for wound healing applications. Curcumin displays strong antioxidant, antiseptic, and anti‐inflammatory properties, while collagen is acknowledged for promoting cell adhesion, migration and differentiation. However, when curcumin is loaded directly into collagen hydrogels, it forms large molecular aggregates and clogs the matrix pores. A double‐encapsulation strategy is therefore developed by loading curcumin into lipid nanoparticles (LNP), and embedding these particles inside collagen scaffolds. The resulting collagen/LNP cryostructurates have an optimal fibrous structure with ≈100 µm average pore size for sustaining cell migration. Results show that collagen is structurally unaltered and that nanoparticles are homogeneously distributed amidst collagen fibers. Hydrogels soaked in saline buffer release about 20 to 30% of their nanoparticles content within 24 h, while achieved 100% release after 25 days. When exposed to NIH 3T3 fibroblasts, these hydrogels provide a satisfactory scaffold for cell interaction as early as 4 h after seeding, with no cytotoxic counter effect. These positive features make the collagen/lipid cryostructurates a promising material for further use in wound healing.  相似文献   

    

Dr. Ruiyan Sun  Anna Kann  Dr. Heinrich Hartmann  Dr. Astrid Besmehn  Dr. Peter J. C. Hausoul  Prof. Dr. Regina Palkovits 《ChemSusChem》2019,12(14):3278-3285

Methyl formate was produced in one pot through the hydrogenation of CO₂ to formic acid/formate followed by an esterification step. The route offers the possibility to integrate renewable energy into the fossil-based chemical value chain. In this work, a phosphine-polymer-anchored Ru complex was shown to be an efficient solid catalyst for the direct hydrogenation of CO₂ to methyl formate. The 1,2-bis(diphenylphosphino)ethane-like polymer presented the highest activity with a turnover number (TON) of up to 3401 at 160 °C. The reaction parameters were systemically investigated to optimize the reaction towards the formation of methyl formate. This catalyst could be reused seven times without a significant decrease in activity. Evolution of the catalytic Ru center during the reaction was revealed, and a possible reaction mechanism was proposed.  相似文献   

    

Dr. Ruiyan Sun  Anna Kann  Dr. Heinrich Hartmann  Dr. Astrid Besmehn  Dr. Peter J. C. Hausoul  Prof. Dr. Regina Palkovits 《ChemSusChem》2019,12(14):3207-3207

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Salih Veziroglu  Muhammad Zubair Ghori  Anna‐Lena Obermann  Katharina Rder  Oleksandr Polonskyi  Thomas Strunskus  Franz Faupel  Oral Cenk Aktas 《physica status solidi (a)》2019,216(14)

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Luis Alberto Rodríguez‐Picn  Anna Patricia Rodríguez‐Picn  Alejandro Alvarado‐Iniesta 《商业与工业应用随机模型》2019,35(3):504-521

Most modern products that are highly reliable are complex in their inner and outer structures. This situation indicates quality characterization by the interaction of multiple performance characteristics, which motivates the utilization of robust reliability models to obtain robust estimates. It is paramount to obtaining substantial information about a product's life cycle; therefore, when multiple performance characteristics are dependent, it is important to find models that address the joint distribution of performance degradation of such. In this paper, a reliability model for products with 2 fatigue‐crack growth characteristics related to 2 degradation processes is developed. The proposed model considers the dependence among degradation processes by using copula functions considering the marginal degradation processes as inverse Gaussian processes. The statistical inference is performed by using a Bayesian approach to estimate the parameters of the joint bivariate model. A time‐scale transformation is considered to assure monotone paths of the degradation trajectories. The comparison results of the reliability analysis, under both dependent and independent assumptions, are reported with the implementation of the proposed modeling in a case study, which consists of the crack propagation data of 2 terminals of an electronic device.  相似文献   

    

Sonja Steffensen  Anna Thünen 《PAMM》2019,19(1)

The multi‐leader‐follower game (MLFG) is a generalization of the Stackelberg game which considers bilevel games with a single leader. Here, the individuals (players) are divided into two groups, namely leaders and followers, according to their position (role) in the game. Mathematically, this yields a hierarchical Nash game, where further minimization problems appear in the leaders' optimization problems as constraints. A Nash equilibrium is then given by a multistrategy vector of all players, where no player has the incentive to change his chosen strategy unilaterally. We derive a Nash equilibrium for a quadratic multi‐leader‐follower game using the nonsmooth best response function of the follower. The existence and uniqueness of solutions are proven for an example and its Nash equilibrium is explicitly computed.  相似文献   

    

Olga Kulakovich  Elena Shabunya-Klyachkovskaya  Liudmila Trotsiuk  Anna Matsukovich  Yauheniya Korza 《Journal of Raman spectroscopy : JRS》2019,50(7):936-944

The methods for the synthesis of gold sols in chloroform have been developed. The efficiency of gold organic sol for studying real objects of painting and its advantage over traditional hydrosol was demonstrated. A new practical application of gold organosols is proposed—the use for analysis of paintings by surface-enhanced Raman scattering that can help to identify the dyes and hydrophobic binders in one probe. In practice, the application of metallic organosols makes possible to substantially simplify the procedure for sample preparation. It was also shown that the intensity of the surface-enhanced Raman spectroscopy bands and the signal-to-noise ratios is improved with organosols in comparison with hydrosol. These results can contribute in the long term to the development of nondestructive approach to the analysis of works of painting.  相似文献   

    

Viktor Yu. Karasev  Elena S. Dzlieva  Sergey I. Pavlov  Olga V. Matvievskaya  Vladimir A. Polischuk  Maxmim A. Ermolenko  Alexey I. Eikhval'd  Anna P. Gorbenko 《等离子体物理论文集》2019,59(4-5)

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