Fano collective resonance as complex mode in a two dimensional planar metasurface of plasmonic nanoparticles

Fano resonances are features in transmissivity/reflectivity/absorption that owe their origin to the interaction between a bright resonance and a dark (i.e., sub-radiant) narrower resonance, and may emerge in the optical properties of planar two-dimensional (2D) periodic arrays (metasurfaces) of plasmonic nanoparticles. In this Letter, we provide a thorough assessment of their nature for the general case of normal and oblique plane wave incidence, highlighting when a Fano resonance is affected by the mutual coupling in an array and its capability to support free modal solutions. We analyze the representative case of a metasurface of plasmonic nanoshells at ultraviolet frequencies and compute its absorption under TE- and TM-polarized, oblique plane-wave incidence. In particular, we find that plasmonic metasurfaces display two distinct types of resonances observable as absorption peaks: one is related to the Mie, dipolar resonance of each nanoparticle; the other is due to the forced excitation of free modes with small attenuation constant, usually found at oblique incidence. The latter is thus an array-induced collective Fano resonance. This realization opens up to manifold flexible designs at optical frequencies mixing individual and collective resonances. We explain the physical origin of such Fano resonances using the modal analysis, which allows to calculate the free modes with complex wavenumber supported by the metasurface. We define equivalent array dipolar polarizabilities that are directly related to the absorption physics at oblique incidence and show a direct dependence between array modal phase and attenuation constant and Fano resonances. We thus provide a more complete picture of Fano resonances that may lead to the design of filters, energy-harvesting devices, photodetectors, and sensors at ultraviolet frequencies.Comment: 6 pages, 5 figure

Description and characterization of the complex modes in a linear chain of gold nanospheres

In this paper, complex modes in a linear chain of gold nanospheres are analyzed, accounting for metal losses. Dispersion diagrams are computed for travelling modes with both longitudinal and transverse (with respect to the array axis) polarization states. The procedure outlined in this work allows for the description of single mode evolution varying frequency, thus the modal dispersion diagrams are composed by the superposition of all the different modes in the one dimensional array. Each nanoparticle is modeled as an electric dipole, by adopting the single dipole approximation, and the complex zeroes of the homogeneous equation characterizing the field in the periodic structure are computed. The Ewald method is employed to analytically continue the periodic Green's function into the complex spectral domain and to achieve rapid convergence. Full characterization of the modes is provided in terms of their direction of propagation (forward/backward), their guidance and radiation properties (bound/leaky), the position of their wavenumber on the Riemann sheet (proper/improper), and also in terms of their possible physical excitation in the structure by a source in proximity of the array or a defect (physical/nonphysical modes). Understanding the modes excitable in this kind of structures is essential for possible applications in which the linear chain can be employed, from near-field enhancement to SERS, and innovative sensors. © 2011 SPIE

Imitation modeling of the static process loading milling cutters

Myelin is a multilayered membrane that ensheathes axonal fibers in the vertebrate nervous system, allowing fast propagation of nerve action potentials. It contains densely packed lipids, lacks an actin-based cytocortex, and requires myelin basic protein (MBP) as its major structural component. This protein is the basic constituent of the proteinaceous meshwork that is localized between adjacent cytoplasmic membranes of the myelin sheath. Yet, it is not clear how MBP influences the organization and dynamics of the lipid constituents of myelin. Here, we used optical stimulated emission depletion super-resolution microscopy in combination with fluorescence correlation spectroscopy to assess the characteristics of diffusion of different fluorescent lipid analogs in myelin membrane sheets of cultured oligodendrocytes and in micrometer-sized domains that were induced by MBP in live epithelial PtK2 cells. Lipid diffusion was significantly faster and less anomalous both in oligodendrocytes and inside the MBP-rich domains of PtK2 cells compared with undisturbed live PtK2 cells. Our data show that MBP reorganizes lipid diffusion, possibly by preventing the buildup of an actin-based cytocortex and by preventing most membrane proteins from entering the myelin sheath region. Yet, in contrast to myelin sheets in oligodendrocytes, the MBP-induced domains in epithelial PtK2 cells demonstrate no change in lipid order, indicating that segregation of long-chain lipids into myelin sheets is a process specific to oligodendrocytes

Controlling the structural formation of porized cement composites in the production of thermally efficient enclosure structures of enhanced quality

ABSTACT: Introduction. Research to improve the quality of foam concrete products through targeted control of technological processes of structure formation of cement-based compositions is relevant. The strength of foam concrete is significantly influenced by the adhesion strength of the hardened cement paste to the aggregate. This article discusses methods of chemical and mechanochemical activation of foam concrete filler with glyoxal-containing additives, interaction with hydration products of binders and increasing the strength of the contact zone. The quality of foam concrete can be improved by controlling the properties of the contact zone. Materials and methods. The study was conducted using standard test procedures specified in national standards. Results. With preliminary chemical and mechano-chemical exposure of the sand surface to glyoxal-containing additives and its subsequent introduction into the foam concrete mixture the grade of strength of foam concrete increases to B1 while maintaining the average density grade D500 in comparison with foam concrete of the control composition, while the shrinkage value decreases by 20–38.5% and thermal conductivity coefficient by 37%. Conclusion. The use of glyoxal-based additives in foam concrete mixtures by pre-activating the sand surface can improve the quality of cement foam concrete

Compact and Loosely Bound Structures in Light Nuclei

A role of different components in the wave function of the weakly bound light nuclei states was studied within the framework of the cluster model, taking into account of orbitals "polarization". It was shown that a limited number of structures associated with the different modes of nucleon motion can be of great importance for such systems. Examples of simple and quite flexible trial wave functions are given for the nuclei $^8$Be, $^6$He. Expressions for the microscopic wave functions of these nuclei were found and used for the calculation of basic nuclear characteristics, using well known central-exchange nucleon-nucleon potentials.Comment: 19 pages, 3 ps figure

ДОСВІД ВИКОРИСТАННЯ ЛАПАРОСКОПІЧНОГО ТРЕНАЖЕРА З МЕТОЮ ПОКРАЩЕННЯ ПРАКТИЧНИХ НАВИЧОК СТУДЕНТІВ-МЕДИКІВ

During the last years an exponential increase of technical equipment role is being observed in surgical practice. Minimally invasive surgical interventions are widely integrated and require specialists to acquire specific skills. Considering inconsistency between educational programs and modern tendencies, there is a need to create new training courses. The article describes experience of laparoscopic trainer box application for improving medical students’ practical skills, who had no laparoscopic experience in the past. Participants completed training course, consisting of seven exercises, on constructed by us laparoscopic box trainer. Assessment of skill improvement was performed, comparing participants’ results at the beginning and end of the course. All participants were able to successfully complete each of the seven laparoscopic exercises, with accomplishment of target level up to the last set. All students refined upon their results in the average from 1.6 to 4.65 times, depending on the exercise. Constructed in the clinic laparoscopic box trainer with the suite of exercises is useful and reasonable for effective increase of practical skills level and motivation of medical students. Early introducing future specialists with standards of mini-invasive surgery is an important part of their educational process and helps to create innovation oriented professional thinking.В останні роки спостерігається експоненціальне збільшення ролі технічного оснащення в практиці лікаря хірургічного профілю. Міні-інвазивні хірургічні втручання зазнають широкої інтеграції та потребують від спеціаліста оволодіння певними специфічними навичками. Враховуючи наявність невідповідності навчальних програм сучасним тенденціям, виникає необхідність створення нових навчальних курсів. У статті показано досвід використання лапароскопічного тренажера для покращення практичних навичок студентів-медиків, які не мали попереднього досвіду лапароскопічної хірургії. На сконструйованому нами бокс-тренажері учасники пройшли навчальний курс, що складається з семи вправ. Оцінка покращення навичок була здійснена шляхом порівняння результатів учасників на початку і в кінці проходження курсу. Всі учасники змогли успішно виконати вправи, з досягненням поставленого цільового рівня. Всі студенти після проходження курсу покращили свої результати в середньому від 1,6 до 4,65 раза, залежно від вправи (p<0,05). Використання самостійно сконструйованих лапароскопічних бокс-тренажерів з розробленим у клініці комплексом вправ є доцільним задля ефективного підвищення практичної підготовки і вмотивованості студентів-медиків. Раннє ознайомлення майбутніх спеціалістів із стандартами міні-інвазивної хірургії є важливою складовою навчального процесу і допомагає створити інноваційно орієнтоване професійне мислення

Institutional transformation of the financial basis of the local self-government

The study investigates the institutional transformation of financial basis of the local self-government in the Czech Republic, Hungary and Poland via comparative qualitative research methods. As a result, the Czech Republic also failed to avoid a downturn, but since 2010, the economy has started to grow and, consequently, there has been an increase in GDP at 1%. In conclusion, local and regional development must be supported by planned finances, rather than by the financing of individual projects, specifically, financial instruments, the structure and flexibility of which is consistent with the objectives of the integrated program of development of local self-government.У дослідженні висвітлено інституційну трансформацію фінансової бази місцевого самоврядування в Чехії, Угорщині та Польщі за допомогою порівняльних якісних методів дослідження. Як результат, Чеська Республіка не змогла уникнути спаду, але з 2010 року економіка почала зростати і, отже, спостерігається зростання ВВП на 1%. На закінчення, місцевий та регіональний розвиток повинен підтримуватися плановими фінансами, а не фінансуванням окремих проектів, зокрема, фінансових інструментів, структура та гнучкість яких відповідає цілям інтегрованої програми розвитку місцевого самоврядування

Institutional transformation of the financial basis of the local self-government

The study investigates the institutional transformation of financial basis of the local self-government in the Czech Republic, Hungary and Poland via comparative qualitative research methods. As a result, the Czech Republic also failed to avoid a downturn, but since 2010, the economy has started to grow and, consequently, there has been an increase in GDP at 1%. In conclusion, local and regional development must be supported by planned finances, rather than by the financing of individual projects, specifically, financial instruments, the structure and flexibility of which is consistent with the objectives of the integrated program of development of local self-government.У дослідженні висвітлено інституційну трансформацію фінансової бази місцевого самоврядування в Чехії, Угорщині та Польщі за допомогою порівняльних якісних методів дослідження. Як результат, Чеська Республіка не змогла уникнути спаду, але з 2010 року економіка почала зростати і, отже, спостерігається зростання ВВП на 1%. На закінчення, місцевий та регіональний розвиток повинен підтримуватися плановими фінансами, а не фінансуванням окремих проектів, зокрема, фінансових інструментів, структура та гнучкість яких відповідає цілям інтегрованої програми розвитку місцевого самоврядування

Formation of porous structures in production technology of construction materials based on building gypsum plaster

ABSTRACT: Introduction. This article presents the results of the research works on formation of building gypsum plaster porous structure with the use of recovered anhydrite raw materials and chemical additives, and describes a method for production of wall materials. The relevance of this paper is stipulated by the need to expand the range and increase the manufacture of heat-insulating and structural-heat-insulating products based on gypsum binders and local mineral raw materials, as well as the development of technologies to ensure the production of gypsum materials with improved performance. The authors proposed certain methods for forming the porous structure of building gypsum plaster and improving its performance in terms of porosity and thermal conductivity through the use of modified recovered raw materials and chemical additives of calcium chloride and sodium carbonate. Materials and methods. The study of the effect of modifying additives on the properties of the mixture was carried out using gypsum paste of normal consistency (NC = 55%). The preparation of samples and testing were performed according to the methods specified in the national standards with the use of porous additives of calcium carbonate, fluoroanhydrite and chemical additives for the rheological properties of the mixture, average density and strength of the samples, the patterns and mechanism of the processes of gypsum stone structure formation were established. Results. The application of fluoroanhydrite modified in the disintegrator with an equimolar amount of calcium carbonate leads to a decrease in the average density of the samples to 40% with evenly distributed pores. The analysis of the microstructure of heat-insulating material samples with a density of 550 kg/m3 showed that the average diameter of micropores is 0.45 mm, while the thermal conductivity of samples with complex chemical additives has the thermal conductivity coefficient of 0.25 W/m°C, which is 30% lower than the thermal conductivity of samples without complex additives. Conclusions. The results obtained create the basis for using recovery raw materials and domestic modifying additives as a pore-forming agent, which allow regulating the structure of gypsum stone in order to produce effective wall material

Hyperbolic metamaterial as super absorber for scattered fields generated at its surface

We show that hyperbolic metamaterials (HMs) that exhibit hyperbolic wave-vector dispersion diagrams possess two important features related to super absorption: The total power scattered by a nanosphere is (i) greatly enhanced when placed at the HM surface, compared to other material surfaces, and (ii) almost totally directed into the HM. We show that these two features are peculiar of HM interfaces, and we support them using a spectral theory study of transverse-electric and magnetic waves scattered by a subwavelength nanosphere. We analyze the nanosphere's scattered power absorbed by various substrate configurations. We also consider various nanosphere materials. © 2012 American Physical Society