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51.
Mindaugas Maciulevičius Antanas Vinčiūnas Marijus Brikas Andrei Butsen Natalie Tarasenka Nikolai Tarasenko Gediminas Račiukaitis 《Applied Physics A: Materials Science & Processing》2013,111(1):289-295
Size of nanoparticles is an important parameter for their applications. The real-time monitoring is required for reliable and reproducible production of nanoparticles with controllable size. We present results of our research on development of the system for the online nanoparticle characterization during their production by a laser. The laser ablation chamber which allows measurements of surface plasmon resonance spectra during the nanoparticle generation process has been designed and fabricated. The online characterization system was tested by producing and modification of gold nanoparticles. Nanoparticles were generated by nanosecond-laser (wavelength 1064 nm) ablation of gold target in deionized water, and optimal conditions for the highest nanoparticle productivity were estimated. The mean diameter of nanoparticles was determined using their absorption spectra measured in the real-time during the ablation experiments and from the TEM images analysis, and it varied from 20 to 45 nm. The mismatch between nanoparticle diameters, estimated using these two methods, is due to the polydispersity of the generated nanoparticles. The further experiments of laser-induced modification of colloidal gold nanoparticles were carried out using second harmonic (wavelength 532 nm) of nanosecond Nd:YAG laser and alteration in nanoparticle size were acquired by the online measurement system. 相似文献
52.
Antanas Karalius Yang Zhang Oleksandr Kravchenko Ulla Elofsson Zoltn Szab Mingdi Yan Olof Ramstrm 《Angewandte Chemie (International ed. in English)》2020,59(9):3434-3438
The nitroaldol reaction is demonstrated as an efficient dynamic covalent reaction in phosphate buffers at neutral pH. Rapid equilibration was recorded with pyridine‐based aldehydes, and dynamic oligomerization could be achieved, leading to nitroaldol dynamers of up to 17 repeating units. The dynamers were applied in a coherent stimuli‐responsive molecular system in which larger dynamers transiently existed out‐of‐equilibrium in a neutral aqueous system rich in formaldehyde, controlled by nitromethane. 相似文献
53.
Assume the Riemann hypothesis. On the right-hand side of the critical strip, we obtain an asymptotic formula for the discrete mean square of the Riemann zeta-function over imaginary parts of its zeros. 相似文献
54.
In this paper we propose a new simplicial partition-based deterministic algorithm for global optimization of Lipschitz-continuous functions without requiring any knowledge of the Lipschitz constant. Our algorithm is motivated by the well-known Direct algorithm which evaluates the objective function on a set of points that tries to cover the most promising subregions of the feasible region. Almost all previous modifications of Direct algorithm use hyper-rectangular partitions. However, other types of partitions may be more suitable for some optimization problems. Simplicial partitions may be preferable when the initial feasible region is either already a simplex or may be covered by one or a manageable number of simplices. Therefore in this paper we propose and investigate simplicial versions of the partition-based algorithm. In the case of simplicial partitions, definition of potentially optimal subregion cannot be the same as in the rectangular version. In this paper we propose and investigate two definitions of potentially optimal simplices: one involves function values at the vertices of the simplex and another uses function value at the centroid of the simplex. We use experimental investigation to compare performance of the algorithms with different definitions of potentially optimal partitions. The experimental investigation shows, that proposed simplicial algorithm gives very competitive results to Direct algorithm using standard test problems and performs particularly well when the search space and the numbers of local and global optimizers may be reduced by taking into account symmetries of the objective function. 相似文献
55.
James M. Calvin Antanas Žilinskas 《Journal of Optimization Theory and Applications》2014,163(2):528-547
The problem of approximating the global minimum of a function of two variables is considered. A method is proposed rooted in the statistical approach to global optimization. The proposed algorithm partitions the feasible region using a Delaunay triangulation. Only the objective function values are required by the optimization algorithm. The asymptotic convergence rate is analyzed for a class of smooth functions. Numerical examples are provided. 相似文献
56.
Algirdas Audzijonis Gediminas Gaigalas Leonardas Žigas Audrius Pauliukas Bronislovas Šalkus Raimundas Žaltauskas Antanas Kvedaravičius Aurimas Čerškus Jurgis Narušis 《Central European Journal of Physics》2008,6(3):415-421
The energy levels of valence bands (VB) in SbSeBr crystals were calculated for investigation of the photoelectron emission
spectra of A5B6C7 — type crystals. The molecular model of this crystal was used for calculation of VB by the Density Functional Theory (DFT)
and Unrestricted Hartree — Fock (UHF) methods. The molecular cluster consisting of 20 molecules of SbSeBr was used for calculations
of averaged total density of states including atom vibrations. The spectra of averaged total density of states from VB in
the SbSeBr cluster were compared with experimental photoelectron emission spectra from VB of A5B6C7 — type crystals. The results of comparison clarify that the atomic vibrations are one of possible reasons for the smoother
appearance of the experimental X-ray photoelectron spectrum (XPS).
相似文献
57.
Antanas Laurinčikas 《Archiv der Mathematik》2007,89(6):552-560
We identify the limit measures in limit theorems in the space of analytic functions and on the complex plane for the Laplace
transform of the square of the Riemann zeta-function.
Received: 22 December 2006 相似文献
58.
59.
A class of test functions for global optimization 总被引:1,自引:0,他引:1
We suggest weighted least squares scaling, a basic method in multidimensional scaling, as a class of test functions for global optimization. The functions are easy to code, cheap to calculate, and have important applications in data analysis. For certain data these functions have many local minima. Some characteristic features of the test functions are investigated.This paper was written while the second author was a visiting Professor at Aachen University of Technology, funded by the Deutsche Forschungsgemeinschaft. 相似文献
60.
Mangirdas Malinauskas Daiva Baltriukiene Antanas Kraniauskas Paulius Danilevicius Rasa Jarasiene Raimondas Sirmenis Albertas Zukauskas Evaldas Balciunas Vytautas Purlys Roaldas Gadonas Virginija Bukelskiene Vytautas Sirvydis Algis Piskarskas 《Applied Physics A: Materials Science & Processing》2012,108(3):751-759
Films and microstructured scaffolds have been fabricated using direct laser writing out of different polymers: hybrid organic-inorganic ORMOCORE b59, acrylate-based AKRE23, novel organic-inorganic Zr containing hybrid SZ2080, and biodegradable PEG-DA-258. Adult myogenic stem cells were grown on these surfaces in vitro. Their adhesion, growth, and viability test results suggest good potential applicability of the materials in biomedical practice. Pieces of these polymers were implanted in rat’s paravertebral back tissue. Histological examination of the implants and surrounding tissue ex vivo after 3 weeks of implantation was conducted and results show the materials to be at least as biocompatible as surgical clips or sutures. The applied direct laser writing technique seems to offer good future prospects in a polymeric 3D scaffold design for artificial tissue engineering with autologous stem cells. 相似文献