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121.
Pradip Hiwale Sandrina Lampis Sergio Murgia 《Journal of Dispersion Science and Technology》2013,34(9):1286-1293
Monoolein, being a biocompatible and bioadhesive penetration enhancer that can form liquid crystalline (LC) phases, possesses remarkable characteristics for addressing drug delivery systems across the biological membrane. A range of formulations based on LC phases were investigated in this study, which includes lamellar, reverse hexagonal, and bicontinuous cubic phases along with an emulsion stabilized by LC phases. Caffeine was chosen as hydophilic model drug to evaluate in vitro release performance. The different monoolein based caffeine formulations were characterized by techniques such as polarized light microscopy, nuclear magnetic resonance (NMR) and small angle x-ray scattering (SAXS). The release experiments, performed through Franz diffusion cells, revealed that the presence of a liquid crystalline (LC) phase prevented burst release in all cases. In addition, taking into consideration that all ingredients are fully biocompatible, the creamy emulsion formulation stabilized by a hexagonal lipid LC phase can be proposed as a challenging preformulation for topical drug delivery. 相似文献
122.
Dennis Cao Dr. Michal Juríček Zachary J. Brown Dr. Andrew C.‐H. Sue Dr. Zhichang Liu Juying Lei Anthea K. Blackburn Dr. Sergio Grunder Dr. Amy A. Sarjeant Prof. Ali Coskun Prof. Cheng Wang Prof. Omar K. Farha Prof. Joseph T. Hupp Prof. J. Fraser Stoddart 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(26):8457-8465
We report the synthesis of two [2]catenane‐containing struts that are composed of a tetracationic cyclophane (TC4+) encircling a 1,5‐dioxynaphthalene (DNP)‐based crown ether, which bears two terphenylene arms. The TC4+ rings comprise either 1) two bipyridinium (BIPY2+) units or 2) a BIPY2+ and a diazapyrenium (DAP2+) unit. These degenerate and nondegenerate catenanes were reacted in the presence of Cu(NO3)2?2.5 H2O to yield Cu‐paddlewheel‐based MOF‐1050 and MOF‐1051. The solid‐state structures of these MOFs reveal that the metal clusters serve to join the heptaphenylene struts into grid‐like 2D networks. These 2D sheets are then held together by infinite donor–acceptor stacks involving the [2]catenanes to produce interpenetrated 3D architectures. As a consequence of the planar chirality associated with both the DNP and hydroquinone (HQ) units present in the crown ether, each catenane can exist as four stereoisomers. In the case of the nondegenerate (bistable) catenane, the situation is further complicated by the presence of translational isomers. Upon crystallization, however, only two of the four possible stereoisomers—namely, the enantiomeric RR and SS forms—are observed in the crystals. An additional element of co‐conformational selectivity is present in MOF‐1051 as a consequence of the substitution of one of the BIPY2+ units by a DAP2+ unit: only the translational isomer in which the DAP2+ unit is encircled by the crown ether is observed. The overall topologies of MOF‐1050 and MOF‐1051, and the selective formation of stereoisomers and translational isomers during the kinetically driven crystallization, provide evidence that weak noncovalent bonding interactions play a significant role in the assembly of these extended (super)structures. 相似文献
123.
Dr. Antonello Di Crescenzo Dr. Luca Bardini Dr. Bruna Sinjari Dr. Tonino Traini Dr. Lisa Marinelli Dr. Mauro Carraro Prof. Raimondo Germani Dr. Pietro Di Profio Prof. Sergio Caputi Prof. Antonio Di Stefano Prof. Marcella Bonchio Prof. Francesco Paolucci Prof. Antonella Fontana 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(48):16415-16423
Novel hydrogel phases based on positively charged and zwitterionic surfactants, namely, N‐[p‐(n‐dodecyloxybenzyl)]‐N,N,N‐trimethylammonium bromide (pDOTABr) and p‐dodecyloxybenzyldimethylamine oxide (pDOAO), which combine pristine carbon nanotubes (CNTs), were obtained, thus leading to stable dispersions and enhanced cross‐linked networks. The composite hydrogel featuring a well‐defined nanostructured morphology and an overall positively charged surface was shown to efficiently immobilise a polyanionic and redox‐active tetraruthenium‐substituted polyoxometalate (Ru4POM) by complementary charge interactions. The resulting hybrid gel has been characterised by electron microscopy techniques, whereas the electrostatic‐directed assembly has been monitored by means of fluorescence spectroscopy and ζ‐potential tests. This protocol offers a straightforward supramolecular strategy for the design of novel aqueous‐based electrocatalytic soft materials, thereby improving the processability of CNTs while tuning their interfacial decoration with multiple catalytic domains. Electrochemical evidence confirms that the activity of the catalyst is preserved within the gel media. 相似文献
124.
Dr. Hong‐Dong Hao Dr. Sergio Wittlin Prof. Dr. Yikang Wu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(23):7605-7619
Perhydrolysis of a sterically congested multifunctional epoxide was achieved in ethereal H2O2 with the aid of a recently developed Mo catalyst. The resulting hydroperoxide cyclized to give a 1,2,4‐trioxane, which could be readily elaborated into qinghaosu and a range of novel analogues. Some of the compounds with two such trioxane moieties showed in vitro antimalarial activity comparable to or even better than that of artesunate or chloroquine. 相似文献
125.
Sergio Mauricio Bonesi Daniele Dondi Stefano Protti Maurizio Fagnoni Angelo Albini 《Tetrahedron letters》2014
Irradiation of triphenylamine (Ph3N) in nitrogen-flushed solution leads to 9-phenylcarbazole and two tetrahydroderivatives (1,2,3,4- and 1,2,7,8-) via disproportionation of the corresponding 4a,4b-dihydrocarbazole. In oxygen-equilibrated solution oxidative cyclization occurs through the intermediacy of a triplet peroxy diradical, which either abstracts a hydrogen atom intramolecularly or (mainly) cleaves back to the reagents. The role of the key intermediates is supported by DFT calculations and by trapping by triarylphosphines (that are thus efficiently oxidized, while preventing the cyclization of Ph3N). The hydroperoxide, on the other hand, causes inefficient co-oxidation of sulfides. 相似文献
126.
Marildes Josefina Lemos Neto Elizabeth de Souza Nascimento Vera Akiko Maihara Paulo Sergio C. Silva Mariza Landgraf 《Journal of Radioanalytical and Nuclear Chemistry》2014,300(2):573-579
Three CRMs of different matrix composition were analysed, representing an environmental matrix sample (BCR–320R Channel Sediment), a botanical matrix sample (SRM 1547 Peach Leaves) and a zoological matrix sample (SRM 1566b Oyster Tissue). The element mass fractions were obtained using the KayWin program. Analytical measurement uncertainty was determined by two approaches: (1) the routine procedure applying combination of the overall uncertainty u(m) = 3.5 % and statistical uncertainty of the peak area determination and (2) the procedure applying the dedicated ERON program for calculating uncertainty. Performance of altogether 31 certified values was tested by means of calculating E n numbers. For the remaining 52 non-certified values, comparison between uncertainties obtained by the two approaches was made. When using the first approach, the E n number showed satisfactory performance in 28 cases; by using the second approach, the E n number showed satisfactory performance in 27 cases. None of the unsatisfactory performances (E n > 1) appeared to be of systematic nature. The uncertainties obtained by applying the two approaches revealed a big extent of consistency. As the present nuclear database lacks lot of data that serve as input to the ERON program, in particular uncertainties of Q 0 factors, estimates need to be introduced for the missing values, emphasising the urgent need to upgrade the database with missing data. 相似文献
127.
Sergio A. Guerrero Carlos M. Sanabría Alirio Palma Justo Cobo Christopher Glidewell 《Acta Crystallographica. Section C, Structural Chemistry》2014,70(4):408-415
(2R*,4S*)‐Methyl 2,3,4,5‐tetrahydro‐1,4‐epoxy‐1H‐benz[b]azepine‐2‐carboxylate, C12H13NO3, (I), and its reduction product (2R*,4S*)‐methyl 4‐hydroxy‐2,3,4,5‐tetrahydro‐1H‐benz[b]azepine‐2‐carboxylate, C12H15NO3, (II), both crystallize as single enantiomers in the space group P212121, while the hydrolysis product (2RS,4SR)‐4‐hydroxy‐2,3,4,5‐tetrahydro‐1H‐benz[b]azepine‐2‐carboxylic acid, C11H13NO3, (III), and the lactone (2RS,5SR)‐8‐(trifluoromethoxy)‐5,6‐dihydro‐1H‐2,5‐methanobenz[e][1,4]oxazocin‐3(2H)‐one, C12H10F3NO3, (IV), both crystallize as racemic mixtures in the space group P21/c. The molecules of compound (IV) are linked into centrosymmetric R22(10) dimers by N—H...O hydrogen bonds, and those of compound (I) are linked into chains by C—H...π(arene) hydrogen bonds. A combination of O—H...O and O—H...N hydrogen bonds links the molecules of compound (III) into sheets containing equal numbers of R44(14) and R44(26) rings, and a combination of C—H...π(arene) hydrogen bonds and three‐centre O—H...(N,O) hydrogen bonds links the molecules of compound (II) into a three‐dimensional framework structure. Comparisons are made with some related compounds. 相似文献
128.
The effect of the Reynolds number in a supersonic isothermal channel flow is studied using a direct numerical simulation (DNS). The bulk Mach number based on the wall temperature is 1.5, and the bulk Reynolds number is increased up to Reτ ≈︁ 1000. The use of van Driest velocity transformation in the presence of heated walls has been questioned due to the poor accuracy at low Reynolds number. For this reason alternative transformations of the velocity profile and turbulence statistics have been proposed, as, for instance, semi-local scalings. We show that the van Driest transformation recovers its accuracy as the Reynolds number is increased. The Reynolds stresses collapse on the incompressible ones, when properly scaled with density, and very good agreement with the incompressible stresses is found in the outer layer. (© 2015 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
129.
Sawan Ali Sergio Davinelli Rita Mencucci Franco Fusi Gianluca Scuderi Ciro Costagliola Giovanni Scapagnini 《Molecules (Basel, Switzerland)》2021,26(4)
Dry eye disease (DED) is a multifactorial condition caused by tear deficiency and accompanied by ocular surface damage. Recent data support a key role of oxidative and inflammatory processes in the pathogenesis of DED. Hyaluronic acid (HA) is widely used in artificial tears to treat DED by improving ocular hydration and reducing surface friction. Crocin (Cr), the main constituent of saffron, is a renowned compound that exhibits potent antioxidant and anti-inflammatory effects. The present study was undertaken to assess the viscosity and muco-adhesiveness of a photoactivated formulation with crosslinked HA (cHA), Cr, and liposomes (cHA-Cr-L). Our aim was also to evaluate whether cHA-Cr-L may exert cytoprotective effects against oxidative and inflammatory processes in human corneal epithelial cells (HCECs). Viscosity was measured using a rotational rheometer, and then the muco-adhesiveness was evaluated. Under hyperosmolarity (450 mOsm), the HCECs were treated with cHA-Cr-L. Interleukin-1β (IL-1β) and tumor necrosis factor α (TNFα) were quantified by quantitative real-time polymerase chain reaction (RT-qPCR). The levels of reactive oxygen species (ROS) were measured using the DCF assay. The combined action of cHA-Cr-L produced a higher viscosity and muco-adhesiveness compared to the control. The anti-inflammatory effect of cHA-Cr-L was achieved through a significant reduction of IL-1β and TNFα (p < 0.001). The results also showed that cHA-Cr-L reduces ROS production under conditions of hyperosmolarity (p < 0.001). We conclude that cHA-Cr-L has potential as a therapeutic agent in DED, which should be further investigated. 相似文献
130.
We develop generalized bounds for quantum single-parameter estimation problems for which the coupling to the parameter is described by intrinsic multisystem interactions. For a Hamiltonian with k-system parameter-sensitive terms, the quantum limit scales as 1/Nk, where N is the number of systems. These quantum limits remain valid when the Hamiltonian is augmented by any parameter-independent interaction among the systems and when adaptive measurements via parameter-independent coupling to ancillas are allowed. 相似文献