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31.
Poor aqueous solubility of active compounds is a major issue in today’s drug delivery. In this study the smartFilm-technology was exploited to improve the dermal penetration efficacy of a poorly soluble active compound (curcumin). Results were compared to the dermal penetration efficacy of curcumin from curcumin bulk suspensions and nanocrystals, respectively. The smartFilms enabled an effective dermal and transdermal penetration of curcumin, whereas curcumin bulk- and nanosuspensions were less efficient when the curcumin content was similar to the curcumin content in the smartFilms. Interestingly, it was found that increasing numbers of curcumin particles within the suspensions increased the passive dermal penetration of curcumin. The effect is caused by an aqueous meniscus that is created between particle and skin if the dispersion medium evaporates. The connecting liquid meniscus causes a local swelling of the stratum corneum and maintains a high local concentration gradient between drug particles and skin. Thus, leading to a high local passive dermal penetration of curcumin. The findings suggest a new dermal penetration mechanism for active compounds from nano-particulate drug delivery systems, which can be the base for the development of topical drug products with improved penetration efficacy in the future. 相似文献
32.
Exploring the Synthesis of a New Group of Chiral Ammonium Salts with Specific Configurations at the Stereogenic Nitrogen Centers 下载免费PDF全文
Dr. Prisca K. Eckert Christopher Golz Dr. Patrick Degen Cornelia Werner Prof. Dr. Heinz Rehage Prof. Dr. Carsten Strohmann 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(12):3268-3272
A group of new chiral dications with a fixed, specific configuration at the stereogenic nitrogen center was created. Stereoselective synthesis and recrystallization give the diastereomerically and enantiomerically pure dications, including a chiral amphiphile with surface‐active properties. 相似文献
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Caterina?Minelli Isabelle?Geissbuehler Rolf?Eckert Horst?Vogel Harry?Heinzelmann Martha?LileyEmail author 《Colloid and polymer science》2004,282(11):1274-1278
We present an extremely versatile method for the lateral organization of nano-scale objects (NOs) based on the phenomenon of polymer demixing. NOs are suspended in a solution of two immiscible polymers, which is used to form a thin polymer film by spin coating. During spin coating the two polymers separate to give a microphase structure, whose length scale depends on the experimental conditions. The NOs spontaneously partition into one or other of the polymer phases resulting in their lateral organization. In this work, the organization of CdSe nanoparticles and fluorescent organic dyes was studied by fluorescence microscopy. The NOs were organized in the polymer film in stochastic patterns or in ordered designs on substrates pre-patterned by soft-lithography techniques. Single-particle measurements, using confocal microscopy, showed that at low concentrations there was little aggregation of the particles. 相似文献
35.
Fracture mechanisms in bulk metallic glassy materials 总被引:1,自引:0,他引:1
We find that the failure of bulk metallic glassy (BMG) materials follows three modes, i.e., shear fracture with a fracture plane significantly deviating from 45 degrees to the loading direction, normal tensile fracture with a fracture plane perpendicular to the loading direction, or distensile fracture in a break or splitting mode with a fracture plane parallel to the loading direction. The actually occurring type of failure strongly depends on the applied loading mode and the microstructure of the material. Extensive evidence indicates that the Tresca fracture criterion is invalid, and for the first time, three fracture criteria are developed for isotropic materials with high strength, such as advanced BMGs or the newly developed bulk nanostructural materials. 相似文献
36.
We analyze the operation of quantum gates for neutral atoms with qubits that are delocalized in space, i.e., the computational basis states are defined by the presence of a neutral atom in the ground state of one out of two trapping potentials. The implementation of single-qubit gates as well as a controlled phase gate between two qubits is discussed and explicit calculations are presented for rubidium atoms in optical microtraps. Furthermore, we show how multiqubit highly entangled states can be created in this scheme. 相似文献
37.
W.Y. Zhang C.H. Chiu L.C. Zhang K. Biswas H. Ehrenberg W.C. Chang J. Eckert 《Journal of magnetism and magnetic materials》2007
The effect of refractory element addition on phase transformation, crystallization behavior and magnetic properties of Pr8.5Fe81.5B10 (addition-free) and Pr8.5Fe81.5M2B10 (M=V, Cr, Nb, Zr, Ti) ribbons has been investigated. The annealed addition-free ribbon as well as the samples with V or Cr additions are mainly composed of the metastable Pr2Fe23B3 phase, whereas annealed ribbons with Nb, Zr or Ti additions primarily consist of Pr2Fe14B and a minor amount of Fe3B/boride. The complete suppression of the metastable Pr2Fe23B3 phase due to Nb, Zr or Ti additions leads to a significant enhancement of the magnetic properties. For example, the remanence, the coercivity and the energy product are remarkably increased from 2.5 kG, 0.4 kOe and 0.2 MG Oe for the addition-free material to 9.2 kG, 4.7 kOe and 7.6 MG Oe for the specimens with Nb addition. The successful elimination of the metastable Pr2Fe23B3 phase is believed to profit from two factors: (a) Nb, Zr or Ti atoms substitute the Pr site, comparatively increase the Pr content, and thus inhibit the nucleation of Pr-lean Pr2Fe23B3 phases, and (b) the formation of Nb, Zr, or Ti borides consumes some part of B, which hinders the generation of the B-rich Pr2Fe23B3 phase. 相似文献
38.
F. W. N. de Boer H. J. Wollersheim H. Emling H. Grein E. Grosse W. Spreng G. Eckert Th. W. Elze K. Stelzer Ch. Lauterbach 《Zeitschrift für Physik A Hadrons and Nuclei》1986,325(4):457-466
In a systematic study of nucleon transfer reactions accompanied by Coulomb excitation we have bombarded152Sm,160Gd and232Th with206, 208pb beams at incident energies close to the Coulomb barrier. Particle-gamma coincidence techniques were used to identify excited states of reaction products populated through inelastic scattering and in nucleon transfer reactions. One-neutron stripping and pick-up reactions on152Sm were observed leading to known states of the rotation alignedi 13/2-bands in153Sm and151Sm. In the160Gd+206, 208Pb systems no significant population of low lying states of product nuclei was found in the nucleon-transfer channels. Large cross sections were observed for one- and two-neutron pick-up from232Th at an incident energy of 6.4 MeV/u. Around the grazing angle they are of the same order of magnitude as the cross section measured for inelastic scattering. The results are analyzed in the framework of semiclassical models. 相似文献
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