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241.
Ramin Ghahremanzadeh Somayyeh Ahadi Maryam Sayyafi Ayoob Bazgir 《Tetrahedron letters》2008,49(29-30):4479-4482
Some new phthalazine derivatives were prepared by reaction of phthalhydrazide and dialkyl acetylenedicarboxylates in the presence of N-heterocycles. 相似文献
242.
Howse JR Jones RA Ryan AJ Gough T Vafabakhsh R Golestanian R 《Physical review letters》2007,99(4):048102
The motion of an artificial microscale swimmer that uses a chemical reaction catalyzed on its own surface to achieve autonomous propulsion is fully characterized experimentally. It is shown that at short times it has a substantial component of directed motion, with a velocity that depends on the concentration of fuel molecules. At longer times, the motion reverts to a random walk with a substantially enhanced diffusion coefficient. Our results suggest strategies for designing artificial chemotactic systems. 相似文献
243.
Multivalent ions induce attractions between polyelectrolytes, but lead to finite-sized bundles rather than macroscopic phase separation. The kinetics of aggregation and bundle formation of actin is tracked using two different fluorescently labeled populations of F-actin. It is found that the growth mode of these bundles evolves with time and salt concentration, varying from an initial lateral growth to a longitudinal one at later stages. The results suggest that kinetics play a role in bundle growth, but not in the lateral size of bundles, which is constant for linear and branched topologies. 相似文献
244.
Tahmineh Akbarzadeh Saeedeh Noushini Somayeh Taban Mohammad Mahdavi Mahsima Khoshneviszadeh Mina Saeedi Saeed Emami Mohammad Eghtedari Yaghoub Sarrafi Mehdi Khoshneviszadeh Maliheh Safavi Kouros Divsalar Mohammad Hassan Moshafi Ali Asadipour Reyhaneh Sabourian Najmeh Edraki Omidreza Firouzi Ramin Miri Abbas Shafiee Alireza Foroumadi 《Molecular diversity》2015,19(2):273-281
245.
Control of Stem‐Cell Behavior by Fine Tuning the Supramolecular Assemblies of Low‐Molecular‐Weight Gelators
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Dr. Laurent Latxague Dr. Michael A. Ramin Ananda Appavoo Pierre Berto Mathieu Maisani Camille Ehret Dr. Olivier Chassande Prof. Philippe Barthélémy 《Angewandte Chemie (International ed. in English)》2015,54(15):4517-4521
Controlling the behavior of stem cells through the supramolecular architecture of the extracellular matrix remains an important challenge in the culture of stem cells. Herein, we report on a new generation of low‐molecular‐weight gelators (LMWG) for the culture of isolated stem cells. The bola‐amphiphile structures derived from nucleolipids feature unique rheological and biological properties suitable for tissue engineering applications. The bola‐amphiphile‐based hydrogel scaffold exhibits the following essential properties: it is nontoxic, easy to handle, injectable, and features a biocompatible rheology. The reported glycosyl‐nucleoside bola‐amphiphiles (GNBA) are the first examples of LMWG that allow the culture of isolated stem cells in a gel matrix. The results (TEM observations and rheology) suggest that the supramolecular organizations of the matrix play a role in the behavior of stem cells in 3D environments. 相似文献
246.
Background
A verb's argument structure defines the number and relationships of participants needed for a complete event. One-argument (intransitive) verbs require only a subject to make a complete sentence, while two- and three-argument verbs (transitives and ditransitives) normally take direct and indirect objects. Cortical responses to verbs embedded into sentences (correct or with syntactic violations) indicate the processing of the verb's argument structure in the human brain. The two experiments of the present study examined whether and how this processing is reflected in distinct spatio-temporal cortical response patterns to isolated verbs and/or verbs presented in minimal context. 相似文献247.
Ghazaleh Imani Shakibaei Ramin Ghahremanzadeh Ayoob Bazgir 《Phosphorus, sulfur, and silicon and the related elements》2013,188(10):1305-1311
Abstract A highly efficient and green method for the synthesis of new 2-(3-(dicyanomethyl)-2-oxoindolin-3-ylthio)acetic acids is described using magnetically recoverable and reusable CuFe2O4 nanoparticles. A wide variety of aryl isatylidene malononitrils underwent Micheal addition with thioacids to afford novel 2-(3-(dicyanomethyl)-2-oxoindolin-3-ylthio)acetic acids in good to excellent yields. The reaction protocol is operationally simple and mild. Moreover, water as solvent makes the reaction procedure eco-friendly and economically viable. All products were characterized by NMR and IR spectroscopies. 相似文献
248.
Coherent control of OH‐free radicals interacting with the spin‐triplet state of a DNA molecule is investigated. A model Hamiltonian for molecular spin singlet‐triplet resonance is developed. We illustrate that the spin‐triplet state in DNA molecules can be efficiently populated, as the spin‐injection rate can be tuned to be orders of magnitudes greater than the decay rate due to small spin‐orbit coupling in organic molecules. Owing to the nano‐second life‐time of OH free radicals, a non‐equilibrium free energy barrier induced by the injected spin triplet state that lasts approximately longer than one‐micro second in room temperature can efficiently block the initial Hydrogen abstraction and DNA damage. For a direct demonstration of the spin‐blockade effect, a molecular simulation based on an ab‐initio Car‐Parrinello molecular dynamics is deployed. © 2010 Wiley Periodicals, Inc. J Comput Chem 2010 相似文献
249.
Ramin Golestanian 《Pramana》2005,64(6):1029-1038
In a fluctuating medium of quantum, thermal, or non-thermal origin, an interaction is induced between external objects that
modify the fluctuations. These interactions can appear in a vast variety of systems, leading to a plethora of interesting
phenomena. Notable examples of these include: (1) like-charge attraction in the presence of multivalent counterions, (2) Ludwig-Soret
effect in charged colloids, (3) mass renormalization of moving defects in a phononic background and moving metallic objects
in EM quantum vacuum, and (4) dissipation due to motion-induced radiation. The fluctuationinduced forces are statistical in
nature, and this could make their measurement very difficult, because the actual value of the force might deviate most of
the time from the predicted average value. 相似文献
250.
Roshanak Rafiei Nazari Ardavan Koohi Ramin KhosraviFarshad Ebrahimi Mojtaba Yaghobi 《Physica B: Condensed Matter》2011,406(13):2626-2631
We have developed a method to study the theory of charge pumping through a continuous quantum wire using the invariant imbedding approach. Using this method, the general properties of quantum charge pumping, with and without inclusion of many-body interactions are investigated. Using the invariant imbedding approach allows us to address directly the complex reflection (R) and transmission (T) matrices across the wire instead of considering the spectrum of the Schrodinger equation. Using the Kohn-Sham version of density functional theory (DFT), the many-body interactions in the quantum wire is investigated. We calculated the pumped current in those two cases. In the case of ignoring the many-body effects, the pumped current depends on the width of the driven potential barriers and in the case of nonequality of the width of barriers, our study predicts a nonzero charge pumping at the phase difference φ=0 even when the driving potentials are equal. In the second case, although the pumped current had sinusoidal dependence on φ but its value significantly decreased and we also observed nonzero pumping at φ=0 even when the driving potentials and their widths are equal, which is consistent with the recent experimental result. 相似文献