Search results for "Note"

Design and experimental validation of a generic model for combinatorial assembly of DNA tiles into 1D-structures.

2010

Abstract Background Quantitative modeling of the self-assembly of DNA tiles leading either to defined end-products or distribution of biopolymers is of practical importance for biotechnology and synthetic biology. Methods The combinatorial process describing tile assembly was implemented into a generic algorithm allowing quantitative description of the population of significant species accumulating during the reaction course. Experimental formation and characterization by optical and electrophoresis approaches of copolymers resulting from the self-assembly of a limited number of half-complementary tiles were used to define and validate generic rules allowing definition of model parameters. …

2016

The photochemistry of benzophenone, a paradigmatic organic molecule for photosensitization, was investigated by means of surface-hopping ab initio molecular dynamics. Different mechanisms were found to be relevant within the first 600 fs after excitation; the long-debated direct (S1 → T1) and indirect (S1 → T2 → T1) mechanisms for population of the low-lying triplet state are both possible, with the latter being prevalent. Moreover, we established the existence of a kinetic equilibrium between the two triplet states, never observed before. This fact implies that a significant fraction of the overall population resides in T2, eventually allowing one to revisit the usual spectroscopic assignm…

Manipulation of antiferromagnetic domain distribution in Mn2 Au by ultrahigh magnetic fields and by strain

2017

Evidence for a spin reorientation in antiferromagnetic (AFM) Mn2Au thin films induced by high magnetic fields as well as by the application of in-plane mechanical stress is provided. The AFM domain population in the samples was investigated by resonant X-ray Magnetic Linear Dichroism (XMLD) measurements at the L3 edge of Mn using a variable linear polarization of the incident photon beam. As grown samples show no XMLD signal due to averaging over a random AFM domain distribution. After the exposure to a 70 T in-plane magnetic field a clear XMLD signal indicating the generation of a preferential AFM domain orientation is obtained. The same type of XMLD signal is observed when the thin films …

BaCoO3 monoclinic structure and chemical bonding analysis: hybrid DFT calculations

2021

Cobalt based perovskites have great potential for numerous applications. Contrary to a generally assumed hexagonal space group (SG P63/mmc) model as the ground state of BaCoO3 (BCO), our hybrid DFT calculations with B1WC density functional and the symmetry group–subgroup derived crystal structure model support the ground state of BCO to be indeed monoclinic, in agreement with recent experimental predictions [Chin et al., Phys. Rev. B, 2019, 100, 205139]. We found for the monoclinic BCO that the C-type anti-ferromagnetic low-spin (AFM LS) state (SG P2/c) is energetically only slightly more preferential at 0 K than the ferromagnetic (FM) LS state (SG C2/c). In turn, these monoclinic structure…

Energy transfer in diiodoBodipy-grafted upconversion nanohybrids.

2015

Steady-state and time-resolved emission studies on nanohybrids consisting of NaYF4:Yb,Er and a diiodo-substituted Bodipy (UCNP-IBDP) show that the Yb(3+) metastable state, formed after absorption of a near-infrared (NIR) photon, can decay via two competitive energy transfer processes: sensitization of IBDP after absorption of a second NIR photon and population of Er(3+) excited states.

Fibre break failure processes in unidirectional composites: evaluation of critical damage states

2016

Earlier work which successfully modelled the kinetics of fibre breakage in unidirectional composites under monotonic tensile loading has been extended to quantify the kinetics of fibre failure during both monotonic and sustained tensile loading. In both cases, failure was seen to occur when a critical density of large clusters (more than 16 fibres are broken within the representative volume element) of fibre breaks developed. However, in monotonic loading failure occurred very quickly after the first development of these large clusters, whereas under sustained loading the composite could accommodate greater levels of large clusters because of the lower applied load. This article is part of …

Naudas zīmju viltojumu atpazīšana specifiskā lāzeru apgaismojumā

2018

Bakalaura darba mērķis ir noskaidrot, vai naudas zīmju apstarošanas metode specifiskā – trihromātiskā – lāzeru apgaismojumā var tikt pielietota eiro valūtas viltojumu atpazīšanai. Izmantojot speciālu ar viedtālruni aprīkotu iekārtu, oriģinālās un viltotās eiro naudas zīmes tika apgaismotas vienlaicīgi ar trīs viļņu garumu lāzeriem (473nm, 532nm un 659nm), un ar viedtālrunī iebūvēto RGB kameru tika uzņemti attēli. Izmantojot RGB pārklāšanās korekcijas algoritmu, iegūtie attēli Matlab vidē tika sadalīti trijos līdz kameras sensoram nonākušās gaismas intensitāti raksturojošos attēlos – pie katra no lāzeriem viens attēls. Šo attēlu masīvu vērtības tika izmantotas parametrisku attēlu iegūšanai. …

Government Economic Regulations in the Sphere of Higher Education during COVID-19 Crisis in Central Asia

2021

Bakalaura darbā tiek pētīta valsts ekonomiskā iejaukšanās, izmantojot augstākās izglītības ekonomisko regulējumu piemēru Vidusāzijā laikā no 2020. gada marta līdz 2021. gada martam. Mērķis ir salīdzināt COVID-19 krīzes ekonomisko ietekmi uz augstāko izglītību un ieviestajiem ekonomikas noteikumiem. Autors pētījumu veic daļēji strukturētu interviju veidā ar vadošo Vidusāzijas augstskolu pārstāvjiem. Galvenā atklātā problēma ir nesagatavotība ātrai pārejai uz tālmācību. Visbiežākie iemesli ir retā tiešsaistes studiju programmu prakse un sabiedrisko preču, piemēram, stabila interneta pieslēguma un elektrības, nodrošināšana. Pētījums arī parādīja, ka reģionā visplašāk izmantotais regulatīvais r…

Comparison of mechanical properties and composition of magnetron sputter and plasma enhanced atomic layer deposition aluminum nitride films

2018

A comparative study of mechanical properties and elemental and structural composition was made for aluminum nitride thin films deposited with reactive magnetron sputtering and plasma enhanced atomic layer deposition (PEALD). The sputtered films were deposited on Si (100), Mo (110), and Al (111) oriented substrates to study the effect of substrate texture on film properties. For the PEALD trimethylaluminum–ammonia films, the effects of process parameters, such as temperature, bias voltage, and plasma gas (ammonia versus N2/H2), on the AlN properties were studied. All the AlN films had a nominal thickness of 100 nm. Time-of-flight elastic recoil detection analysis showed the sputtered films t…

Deep traps in InGaN/GaN single quantum well structures grown with and without InGaN underlayers

2020

The electrical properties and deep trap spectra were compared for near-UV GaN/InGaN quantum well (QW) structures grown on free-standing GaN substrates. The structures differed by the presence or absence of a thin (110 nm) InGaN layer inserted between the high temperature GaN buffer and the QW region. Capacitance-voltage profiling with monochromatic illumination showed that in the InGaN underlayer (UL), the density of deep traps with optical threshold near 1.5 eV was much higher than in the QW and higher than for structures without InGaN. Irradiation with 5 MeV electrons strongly increased the concentration of these 1.5 eV traps in the QWs, with the increase more pronounced for samples witho…