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91.
We have used a self-assembling monolayer of dodecanethiole molecules as the resist for a lithography technique based on a beam of metastable helium atoms. Doses as low as 3 metastable helium atoms per 10 molecules are enough to write patterns into this resist. An edge resolution of 30 nanometers is demonstrated. The writing mechanism is based on the damage of the resist due to Penning ionization. 相似文献
92.
93.
In the first part [1] of our paper a kinetic model for the band-like beam discharge plasma in hydrogen was derived, numerically obtained results on the ionization and dissociation degree were presented and a detailed explanation of the influence of the electron kinetic properties on the macroscopic plasma behaviour was given. Continuing these investigations, we now report and discuss the results on the ion- and metastable atom-budget. On this basis an analysis is made of the resulting balance equation system with a view to finding the most important physical processes, and a simplified equation system is derived which allows to interpret the essential features of the macroscopic plasma properties. 相似文献
94.
95.
Probing Functional Heteromeric Chemokine Protein–Protein Interactions through Conformation‐Assisted Oxime Ligation
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Stijn M. Agten Dr. Rory R. Koenen Dr. Hans Ippel Veit Eckardt Dr. Philipp von Hundelshausen Prof. Dr. Kevin H. Mayo Prof. Dr. Tilman M. Hackeng 《Angewandte Chemie (International ed. in English)》2016,55(48):14963-14966
Protein–protein interactions (PPIs) govern most processes in living cells. Current drug development strategies are aimed at disrupting or stabilizing PPIs, which require a thorough understanding of PPI mechanisms. Examples of such PPIs are heteromeric chemokine interactions that are potentially involved in pathological disorders such as cancer, atherosclerosis, and HIV. It remains unclear whether this functional modulation is mediated by heterodimer formation or by the additive effects of mixed chemokines on their respective receptors. To address this issue, we report the synthesis of a covalent RANTES‐PF4 heterodimer (termed OPRAH) by total chemical synthesis and oxime ligation, with an acceleration of the final ligation step driven by PPIs between RANTES and PF4. Compared to mixed separate chemokines, OPRAH exhibited increased biological activity, thus providing evidence that physical formation of the heterodimer indeed mediates enhanced function. 相似文献
96.
Hongju Ma Fan Zhang Elisabeth Ignatz Martin Suehnel Peng Xue Patrick Scheerer Lars Oliver Essen Norbert Krauß Tilman Lamparter 《Photochemistry and photobiology》2017,93(1):323-330
The (6‐4) photolyases of the FeS‐BCP group can be considered as the most ancient type among the large family of cryptochrome and photolyase flavoproteins. In contrast to other photolyases, they contain an Fe‐S cluster of unknown function, a DMRL chromophore, an interdomain loop, which could interact with DNA, and a long C‐terminal extension. We compared DNA repair and photoreduction of two members of the FeS‐BCP family, Agrobacterium fabrum PhrB and Rhodobacter sphaeroides RsCryB, with a eukaryotic (6‐4) photolyase from Ostreococcus, OsCPF, and a member of the class III CPD photolyases, PhrA from A. fabrum. We found that the low DNA repair effectivity of FeS‐BCP proteins is largely stimulated by Mg2+ and other divalent cations, whereas no effect of divalent cations was observed in OsCPF and PhrA. The (6‐4) repair activity in the presence of Mg2+ is comparable with the repair activities of the other two photolyases. The photoreduction, on the other hand, is negatively affected by Mg2+ in PhrB, but stimulated by Mg2+ in PhrA. A clear relationship of Mg2+ dependency on DNA repair with the evolutionary position conflicts with Mg2+ dependency of photoreduction. We discuss the Mg2+ effect in the context of structural data and DNA binding. 相似文献
97.
Heidemann R Raitzsch U Bendkowsky V Butscher B Löw R Santos L Pfau T 《Physical review letters》2007,99(16):163601
We report on strong van der Waals blockade in two-photon Rydberg excitation of ultracold magnetically trapped 87Rb atoms. The excitation dynamics was investigated for a large range of densities and laser intensities and shows a full saturation and a strong suppression with respect to single-atom behavior. The observed scaling of the initial increase with density and laser intensity provides evidence for coherent collective excitation. This coherent collective behavior, that was observed for up to several thousand atoms per blockade volume, is generic for all mesoscopic systems which are able to carry only one single quantum of excitation. 相似文献
98.
Shoshan MS Shalev DE Adriaens W Merkx M Hackeng TM Tshuva EY 《Chemical communications (Cambridge, England)》2011,47(22):6407-6409
The first NMR structure of a Cu(I)-bound metallochaperone model with the conserved sequence MT/HCXXC revealed that at pH ~3.0 and ~6.8 Cu(I) binds through one Cys and the Met rather than the two Cys residues, differently than at pH ~8.5. This suggests a possible role of Met in metal transport. 相似文献
99.
S Burney R Wenzel T Kottke T Roussel N Hoang JP Bouly R Bittl J Heberle M Ahmad 《Angewandte Chemie (International ed. in English)》2012,51(37):9356-9360
A quick switch: A single amino acid substitution at a conserved residue (D396N) of Arabidopsis cryptochrome-1 (Atcry1) confers single-stranded DNA repair activity in?vitro, conferring photolyase activity onto the cryptochrome. The mutant protein undergoes photoreduction of flavin to the fully reduced anionic form, similar to photolyases and unlike wild-type cryptochromes. 相似文献
100.
We present a holographic imaging device with a low-coherence light source that uses the reflection of the objective lens as reference illumination. This results in a simple setup and allows applications to microscopy with only small modifications of the setup for aberration measurements. In addition, it opens the prospects to in vivo ophthalmic imaging. We present in vitro experiments using a resolution test target to quantify the system performance. We demonstrate that we can achieve diffraction-limited resolution and show the possibility of aberration correction. We also present preliminary results using a scattering sample. 相似文献