Plasmonic nanocrystals with complex shapes for photocatalysis and growth: Contrasting anisotropic hot-electron generation with the photothermal effect

In plasmonics, and particularly in plasmonic photochemistry, the effect of hot-electron generation is an exciting phenomenon driving new fundamental and applied research. However, obtaining a microscopic description of the hot-electron states represents a challenging problem, limiting our capability to design efficient nanoantennas exploiting these excited carriers. This paper addresses this limitation and studies the spatial distributions of the photophysical dynamic parameters controlling the local surface photochemistry on a plasmonic nanocrystal. We found that the generation of energetic electrons and holes in small plasmonic nanocrystals with complex shapes is strongly position-dependent and anisotropic, whereas the phototemperature across the nanocrystal surface is nearly uniform. Our formalism includes three mechanisms for the generation of excited carriers: the Drude process, the surface-assisted generation of hot-electrons in the sp-band, and the excitation of interband d-holes. Our computations show that the hot-carrier generation originating from these mechanisms reflects the internal structure of hot spots in nanocrystals with complex shapes. The injection of energetic carriers and increased surface phototemperature are driving forces for photocatalytic and photo-growth processes on the surface of plasmonic nanostructures. Therefore, developing a consistent microscopic theory of such processes is necessary for designing efficient nanoantennas for photocatalytic applications

Universal imprinting of chirality with chiral light by employing plasmonic metastructures

Chirality, either of light or matter, has proved to be very practical in biosensing and nanophotonics. However, the fundamental understanding of its temporal dynamics still needs to be discovered. A realistic setup for this are the so-called metastructures, since they are optically active and are built massively, hence rendering an immediate potential candidate. Here we propose and study the electromagnetic-optical mechanism leading to chiral optical imprinting on metastructures. Induced photothermal responses create anisotropic permittivity modulations, different for left or right circularly polarized light, leading to temporal-dependent chiral imprinting of hot-spots, namely imprinting of chirality. The above effect has not been observed yet, but it is within reach of modern experimental approaches. The proposed nonlinear chiroptical effect is general and should appear in any anisotropic material; however, we need to design a particular geometry for this effect to be strong. These new chiral time-dependent metastructures may lead to a plethora of applications.Comment: Main (29 pages, 6 figures) and supplemental (46 pages, 35 figures

On the parasites of genus Angiostrongylus (Nematoda: Angiostrongylidae) and some cases of Angiostrongylus daskalovi in badgers from bulgaria

In the course of studies on filariid infections in wild carnivorous in Bulgaria nematodes of genus Angiostrongylus were found in the heart and pulmonary arteries of badgers. The detected specimens were examined morphologically and metrically, which allowed us to identify them as Angiostrongylusdaskalovi . A morphometrical description of the species is given in accordance with the present materials.В ходе исследования филариидных инвазий в Болгарии в сердце и легочных артериях барсуков обнаружены нематоды рода Angiostrongylus . Эти образцы исследовались морфологически и метрически, что позволило, с учетом также географического и гостального распространения, идентифицировать их как Angiostrongylus daskalovi Janchev et Genov 1988. Приводится морфометрическое описание вида по данным текущих исследований

ФАУНА ЛЕГОЧНЫХ ГЕЛЬМИНТОВ В ОРГАНИЗМЕ ХОЗЯИНА, ЕЕ БИОЛОГИЧЕСКАЯ И ТАКСОНОМИЧЕСКАЯ КЛАССИФИКАЦИЯ

Object of study: Studies of lung helminths from various groups were performed. Elaboration of biological and taxonomic classification of these species has been proposed.Materials and methods: 16 species from families Cervidae, Bovidae, Leporidae and humans were studied for lung helminths inRussia (South and central),Armenia,Bulgaria,Poland. The helminths found were studied using a scope of traditional and elaborated helminthological methods.Results and discussion: In lungs of mammals studied 23 helminth species have been found including 1 of Taeniidae (Echinococcus granulosus), 4 of Dictyocaulidae and 18 of Protostrongylidae. We have divided species composition of these lung helminths into three biological groups. The first biological group included nematodes from Dictyocaulidae family. Life cycles of those helminths are monoxenous (they are geohelminths). The second group includes helminths from family Protostrongylidae. Their life cycles include intermediate hosts – land snails and so they are dixenous (biohelminths). The third group includes an agent of a quite dangerous zoonosis – Echinococcus granulosis larvae. These cestodes also develop per dixenous type, but their intermediate hosts are vertebrates with definitive hosts also vertebrate, mostly carnivores. Taxonomic classification for family Protostrongylidae haelminths is also proposed.Цель исследования: Провести изучение различных групп легочных гельминтов; разработать биологическую и таксономическую классификацию данного вида гельминтов.Материалы и методы: Проведены исследования 16 видов гельминтов семейств Cervidae, Bovidae, Leporidae, а также легочных гельминтов человека на территории России (Юг и центральные районы), Армении, Болгарии, Польши. Обнаруженные гельминты были изучены с использованием традиционных и новых методов гельминтологического исследования.Результаты и обсуждение: В легких у исследованных млекопитающих, найдено 23 вида гельминтов, включая 1 Taeniidae (Echinococcus granulosus), 4 Dictyocaulidae и 18 Protostrongylidae. Мы разделили все эти легочные гельминты на три биологические группы. В первую группу (геогельминты) вошли нематоды семейства Dictyocaulidae. Жизненный цикл данного вида гельминтов моноксенический, осуществляется прямым путём, без промежуточных хозяев. Вторая группа (биогельминты) включала в себя гельминты семейства Protostrongylidae. Характерным признаком является участие в их биологическом цикле промежуточных хозяев — наземных моллюсков. К третьей группе были отнесены возбудители довольно опасного зооноза – Echinococcus granulosis larvae. Эти цестоды развиваются со сменой хозяев, но их промежуточными хозяевами являются позвоночные млекопитающие, имеющие окончательных хозяев – также позвоночных, в основном, плотоядных животных. Нами также предложена таксономическая классификация семейства Protostrongylidae haelminths

Coulomb excitation of exotic nuclei at the R3B-LAND setup

Exotic Ni isotopes have been measured at the R3B-LAND setup at GSI in Darmstadt, using Coulomb excitation in inverse kinematics at beam energies around 500 MeV/u. As the experimental setup allows kinematically complete measurements, the excitation energy was reconstructed using the invariant mass method. The GDR and additional low-lying strength have been observed in 68Ni, the latter exhausting 4.1(1.9)% of the E1 energy-weighted sum rule. Also, the branching ratio for the non-statistical decay of the excited 68Ni nuclei was measured and amounts to 24(4)%.Comment: 11 pages, 7 figures. Invited Talk given at the 11th International Conference on Nucleus-Nucleus Collisions (NN2012), San Antonio, Texas, USA, May 27-June 1, 2012. To appear in the NN2012 Proceedings in Journal of Physics: Conference Series (JPCS

Strong neutron pairing in core+4n nuclei

The emission of neutron pairs from the neutron-rich N=12 isotones C18 and O20 has been studied by high-energy nucleon knockout from N19 and O21 secondary beams, populating unbound states of the two isotones up to 15 MeV above their two-neutron emission thresholds. The analysis of triple fragment-n-n correlations shows that the decay N19(-1p)C18∗→C16+n+n is clearly dominated by direct pair emission. The two-neutron correlation strength, the largest ever observed, suggests the predominance of a C14 core surrounded by four valence neutrons arranged in strongly correlated pairs. On the other hand, a significant competition of a sequential branch is found in the decay O21(-1n)O20∗→O18+n+n, attributed to its formation through the knockout of a deeply bound neutron that breaks the O16 core and reduces the number of pairs

Quasifree (p, 2p) Reactions on Oxygen Isotopes: Observation of Isospin Independence of the Reduced Single-Particle Strength

Quasifree one-proton knockout reactions have been employed in inverse kinematics for a systematic study of the structure of stable and exotic oxygen isotopes at the R3B/LAND setup with incident beam energies in the range of 300-450 MeV/u. The oxygen isotopic chain offers a large variation of separation energies that allows for a quantitative understanding of single-particle strength with changing isospin asymmetry. Quasifree knockout reactions provide a complementary approach to intermediate-energy one-nucleon removal reactions. Inclusive cross sections for quasifree knockout reactions of the type OA(p,2p)NA-1 have been determined and compared to calculations based on the eikonal reaction theory. The reduction factors for the single-particle strength with respect to the independent-particle model were obtained and compared to state-of-the-art ab initio predictions. The results do not show any significant dependence on proton-neutron asymmetry

Effective proton-neutron interaction near the drip line from unbound states in 25,26 F

Background: Odd-odd nuclei, around doubly closed shells, have been extensively used to study proton-neutron interactions. However, the evolution of these interactions as a function of the binding energy, ultimately when nuclei become unbound, is poorly known. The F26 nucleus, composed of a deeply bound π0d5/2 proton and an unbound ν0d3/2 neutron on top of an O24 core, is particularly adapted for this purpose. The coupling of this proton and neutron results in a Jπ=11+-41+ multiplet, whose energies must be determined to study the influence of the proximity of the continuum on the corresponding proton-neutron interaction. The Jπ=11+,21+,41+ bound states have been determined, and only a clear identification of the Jπ=31+ is missing. Purpose: We wish to complete the study of the Jπ=11+-41+ multiplet in F26, by studying the energy and width of the Jπ=31+ unbound state. The method was first validated by the study of unbound states in F25, for which resonances were already observed in a previous experiment. Method: Radioactive beams of Ne26 and Ne27, produced at about 440AMeV by the fragment separator at the GSI facility were used to populate unbound states in F25 and F26 via one-proton knockout reactions on a CH2 target, located at the object focal point of the R3B/LAND setup. The detection of emitted γ rays and neutrons, added to the reconstruction of the momentum vector of the A-1 nuclei, allowed the determination of the energy of three unbound states in F25 and two in F26. Results: Based on its width and decay properties, the first unbound state in F25, at the relative energy of 49(9) keV, is proposed to be a Jπ=1/2- arising from a p1/2 proton-hole state. In F26, the first resonance at 323(33) keV is proposed to be the Jπ=31+ member of the Jπ=11+-41+ multiplet. Energies of observed states in F25,26 have been compared to calculations using the independent-particle shell model, a phenomenological shell model, and the ab initio valence-space in-medium similarity renormalization group method. Conclusions: The deduced effective proton-neutron interaction is weakened by about 30-40% in comparison to the models, pointing to the need for implementing the role of the continuum in theoretical descriptions or to a wrong determination of the atomic mass of F26