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241.
242.
Dr. Jenifer Pendiuk Gonçalves Duangkamol Promlok Tsvetomir Ivanov Shijia Tao Timo Rheinberger Seong-Min Jo Yingjie Yu Robert Graf Manfred Wagner Assoc. Prof. Daniel Crespy Frederik R. Wurm Dr. Lucas Caire da Silva Prof. Shuai Jiang Prof. Katharina Landfester 《Angewandte Chemie (International ed. in English)》2023,62(11):e202216966
Living organisms compartmentalize their catalytic reactions in membranes for increased efficiency and selectivity. To mimic the organelles of eukaryotic cells, we develop a mild approach for in situ encapsulating enzymes in aqueous-core silica nanocapsules. In order to confine the sol-gel reaction at the water/oil interface of miniemulsion, we introduce an aminosilane to the silica precursors, which serves as both catalyst and an amphiphilic anchor that electrostatically assembles with negatively charged hydrolyzed alkoxysilanes at the interface. The semi-permeable shell protects enzymes from proteolytic attack, and allows the transport of reactants and products. The enzyme-carrying nanocapsules, as synthetic nano-organelles, are able to perform cascade reactions when enveloped in a polymer vesicle, mimicking the hierarchically compartmentalized reactions in eukaryotic cells. This in situ encapsulation approach provides a versatile platform for the delivery of biomacromolecules. 相似文献
243.
Claudia Morilla Elianis Perdomo Ana Karla Hernndez Ramcy Regalado Amisel Almirall Gastn Fuentes Yaima Campos Mora Timo Schomann Alan Chan Luis J. Cruz 《Molecules (Basel, Switzerland)》2021,26(11)
Calcium phosphate cements have the advantage that they can be prepared as a paste that sets in a few minutes and can be easily adapted to the shape of the bone defect, which facilitates its clinical application. In this research, six formulations of brushite (dicalcium phosphate dihydrated) cement were obtained and the effect of the addition of sodium alginate was analyzed, such as its capacity as a tetracycline release system. The samples that contain sodium alginate set in 4 or 5 min and showed a high percentage of injectability (93%). The cements exhibit compression resistance values between 1.6 and 2.6 MPa. The drug was released in a range between 12.6 and 13.2% after 7 days. The antimicrobial activity of all the cements containing antibiotics was proven. All samples reached values of cell viability above 70 percent. We also observed that the addition of the sodium alginate and tetracycline improved the cell viability. 相似文献
244.
Marcin Lindner Dr. Michal Valášek Prof. Dr. Marcel Mayor Timo Frauhammer Prof. Dr. Wulf Wulfhekel Dr. Lukas Gerhard 《Angewandte Chemie (International ed. in English)》2017,56(28):8290-8294
We present a self-assembled template that consists of tetraphenylmethane derivatives and adopts a periodic lateral arrangement on a Au(111) surface with acetyl groups sticking out of the molecular film. By using the tip of a scanning tunneling microscope, these acetyl groups can be removed in a spatially controlled way without significantly affecting the remaining molecular assembly. The chemically modified molecules can be readily distinguished from the original ones such that information can be engraved in the molecular film. Both the modified nature of an individual molecule and the order of the molecular film are shown to persist at room temperature. The mesh size of this molecular graph paper can be tuned by varying the length of the molecular spacer so that writing and reading information on the nanoscale with variable letter sizes becomes possible. 相似文献
245.
246.
We report the first large-scale statistical study of very high-lying eigenmodes (quantum states) of the mushroom billiard proposed by L. A. Bunimovich [Chaos 11, 802 (2001)]. The phase space of this mixed system is unusual in that it has a single regular region and a single chaotic region, and no KAM hierarchy. We verify Percival's conjecture to high accuracy (1.7%). We propose a model for dynamical tunneling and show that it predicts well the chaotic components of predominantly regular modes. Our model explains our observed density of such superpositions dying as E(-1/3) (E is the eigenvalue). We compare eigenvalue spacing distributions against Random Matrix Theory expectations, using 16,000 odd modes (an order of magnitude more than any existing study). We outline new variants of mesh-free boundary collocation methods which enable us to achieve high accuracy and high mode numbers (approximately 10(5)) orders of magnitude faster than with competing methods. 相似文献
247.
248.
Antero Aspiala Timo Lotta Juhani Murto Markku Rāsānen V.P. Gupta 《Chemical physics letters》1984,109(2):179-183
2-chloroallyl alcohol has been studied in low-temperature Ar, Kr, Xe, N2 and CH4 matrices. An IR-induced process was found in all media except CH4 and resulted in a steady state dependent on the Wavelength of the irradiation. At elevated temperatures thermal conformer interconversions occurred. The energetics of the processes are discussed and their potential barriers determined. No mode selectivity was found. 相似文献
249.
The traveling tournament problem (TTP) consists of finding a distance-minimal double round-robin tournament where the number of consecutive breaks is bounded. Easton et al. (2001) introduced the so-called circular TTP instances, where venues of teams are located on a circle. The distance between neighboring venues is one, so that the distance between any pair of teams is the distance on the circle. It is empirically proved that these instances are very hard to solve due to the inherent symmetry. This note presents new ideas to cut off essentially identical parts of the solution space. Enumerative solution approaches, e.g. relying on branch-and-bound, benefit from this reduction. We exemplify this benefit by modifying the DFS∗ algorithm of Uthus et al. (2009) and show that speedups can approximate factor 4n. 相似文献
250.
Heidi Appelblom Aura Sipponen Antti Valanne Tero Soukka Timo L?vgren Pauliina Niemel? 《Mikrochimica acta》2011,172(1-2):25-29
A single-labeled peptide probe for measuring peptide phosphorylation status was developed by using a phosphate sensitive terbium chelate. The activity of Abl protein tyrosine kinase and T-cell protein Tyrosine phosphatase (TC PTP) was monitored in real time. To study the probe design in detail, variable substrate peptide sequences, where the enzyme target site was located from two to five amino acids apart from the nearest tyrosine residue, were synthesized. The maximum change observed in fluorescence intensity after phosphorylation was up to 320%, when the phosphorylated tyrosine was located two amino acids from the lysine coupled to the phosphate sensitive terbium chelate, demonstrating an excellent performance for a homogeneous assay. Also the longer distance of five amino acids between the phosphorylated tyrosine residue and terbium chelate resulted up to 260% change in fluorescence intensity. Figure
A principle of the short peptide probe (EAI?\Y?\AAPFAK) with phosphate sensitive terbium chelate attached to the lysine side chain is described, which is proved applicable to measure in real time Abl protein tyrosine kinase and T?\cell protein tyrosine phosphatase activities. Enhancement of the terbium fluorescence could be measured upon addition of a phosphor residue to the nearby tyrosine side chain. The opposite effect could be measured, when phosphor residue is removed by protein tyrosine phosphatase. 相似文献