Plasmonic nanoparticle monomers and dimers: From nano-antennas to chiral metamaterials

We review the basic physics behind light interaction with plasmonic nanoparticles. The theoretical foundations of light scattering on one metallic particle (a plasmonic monomer) and two interacting particles (a plasmonic dimer) are systematically investigated. Expressions for effective particle susceptibility (polarizability) are derived, and applications of these results to plasmonic nanoantennas are outlined. In the long-wavelength limit, the effective macroscopic parameters of an array of plasmonic dimers are calculated. These parameters are attributable to an effective medium corresponding to a dilute arrangement of nanoparticles, i.e., a metamaterial where plasmonic monomers or dimers have the function of "meta-atoms". It is shown that planar dimers consisting of rod-like particles generally possess elliptical dichroism and function as atoms for planar chiral metamaterials. The fabricational simplicity of the proposed rod-dimer geometry can be used in the design of more cost-effective chiral metamaterials in the optical domain.Comment: submitted to Appl. Phys.

URINARY SYSTEM PATHOLOGY IN CHILDREN POPULATION OF KHARKIV REGION: MORBIDITY AND SOME RISK FACTORS

Urinary system pathology in children now is one of the most important problems of medical science. The aim of this study – to analyze the morbidity and reveal the risk factors for development of urinary system diseases in children of Kharkiv region. Materials and methods. The material of the study was the information (gender, age, weight and body length at birth, gestational age, clinical diagnosis), obtained during hospitalization of 663 patients aged from 3 months to 17 years in the nephrological center of Kharkiv regional children clinical hospital during the period from 2012 to 2013 years. Results. The authors found that in children population of Kharkiv region among all diseases of urinary system a significant number of cases occur in congenital malformations, dismetabolic nephropathy, urolithiasis. Conclusions. Regional risk factors for development of urinary system pathology in children are female and living in the village. Decreased weight and body length at birth are risk factors for development in children urinary system congenital malformations

НЕФРОЛОГІЧНА ПАТОЛОГІЯ У ДІТЕЙ ХАРКІВСЬКОЇ ОБЛАСТІ

Нефрологическая заболеваемость и инвалидность являются важными индикаторами состояния здоровья детского населения. Целью данного исследования является выявление региональных особенностей заболеваемости и распространенности нефрологической патологии среди детей Харьковской области и анализ деятельности нефрологической службы оказания помощи детскому населению Харьковской области. Материал и методы. Материалом для данного исследования является отчетная документация о состоянии нефрологической помощи детям Харьковской области за период с 2009 по 2011 года и данные Центра медицинской статистики Министерства здравоохранения Украины. Результаты исследования. Определена структура, заболеваемость и распространенность основных болезней органов мочевой системы у детей. Проанализированы основные показатели работы детской нефрологической службы в Харьковской области. Выводы. Проведенное авторами исследование позволит провести правильные и аргументированные лечебно-реабилитационные мероприятия на  всех этапах оказания специализированной медицинской помощи детям с нефрологической патологией и разработать программы, направленные на улучшение показателей здоровья и профилактику инвалидности в детском возрасте

Morphological features of the uterus in women at different time intervals of the postmortem period as diagnostic criteria for establishing the postmortem interval

The aim is to identify the morphological features of the uterus layers in women at different time intervals of the postmortem period as diagnostic criteria for establishing the postmortem interval. Materials and methods: In the study we used surgical and autopsy material – uterine tissue fragments. All materials were divided into two groups. The 1st group (G 1) included surgical material from women (n=6) who underwent removal of the uterus, or uterus with the appendages due to leiomyoma, uterine prolapse. The 2nd group (G 2) included autopsy material from 42 women with known causes of death and postmortem period (from 24 to 48 hours – 6 cases, from 49 to 72 hours – 7 cases, from 73 to 96 hours – 8 cases, from 97 to 120 hours – 6 cases, from 121 to 144 hours – 8 cases, more than 144 hours – 7 cases). Histological and immunohistochemical study methods were used. Results: A comprehensive morphological study of the women uterus revealed a time-dependent increase of postmortem changes in this organ linked with the increase of postmortem period. In cases of postmortem period duration up to 144 hours, the structural elements of the uterine layers were identified. In cases where the duration of the postmortem period was more than 145 hours, microscopically the uterus was represented by eosinophilic fibrous or dusty masses, the histogenesis of which could not be determined. The processes of autolysis occurred more intensely and faster in the mucous membrane of the uterus, in comparison with the muscular and serous membranes, and in the vessels – in their inner membrane, in comparison with the middle and outer membranes. Autolytic changes in the muscular membrane of the uterus and vascular walls occurred more intensely in muscle fibers compared to connective tissue fibers. Conclusions: The histological and immunohistochemical features of the women uterus at different postmortem periods have a certain forensic medical significance and can be used for establishing the postmortem interval

Anisotropic nanomaterials: structure, growth, assembly, and functions

Comprehensive knowledge over the shape of nanomaterials is a critical factor in designing devices with desired functions. Due to this reason, systematic efforts have been made to synthesize materials of diverse shape in the nanoscale regime. Anisotropic nanomaterials are a class of materials in which their properties are direction-dependent and more than one structural parameter is needed to describe them. Their unique and fine-tuned physical and chemical properties make them ideal candidates for devising new applications. In addition, the assembly of ordered one-dimensional (1D), two-dimensional (2D), and three-dimensional (3D) arrays of anisotropic nanoparticles brings novel properties into the resulting system, which would be entirely different from the properties of individual nanoparticles. This review presents an overview of current research in the area of anisotropic nanomaterials in general and noble metal nanoparticles in particular. We begin with an introduction to the advancements in this area followed by general aspects of the growth of anisotropic nanoparticles. Then we describe several important synthetic protocols for making anisotropic nanomaterials, followed by a summary of their assemblies, and conclude with major applications

Directing Cluster Formation of Au Nanoparticles from Colloidal Solution

Discrete clusters of closely spaced Au nanoparticles can be utilized in devices from photovoltaics to molecular sensors because of the formation of strong local electromagnetic field enhancements when illuminated near their plasmon resonance. In this study, scalable, chemical self-organization methods are shown to produce Au nanoparticle clusters with uniform nanometer interparticle spacing. The performance of two different methods, namely electrophoresis and diffusion, for driving the attachment of Au nanoparticles using a chemical cross-linker on chemically patterned domains of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) thin films are evaluated. Significantly, electrophoresis is found to produce similar surface coverage as diffusion in 1/6th of the processing time with an ~2-fold increase in the number of Au nanoparticles forming clusters. Furthermore, average interparticle spacing within Au nanoparticle clusters was found to decrease from 2-7 nm for diffusion deposition to approximately 1-2 nm for electrophoresis deposition, and the latter method exhibited better uniformity with most clusters appearing to have about 1 nm spacing between nanoparticles. The advantage of such fabrication capability is supported by calculations of local electric field enhancements using electromagnetic full-wave simulations from which we can estimate surface-enhanced Raman scattering (SERS) enhancements. In particular, full-wave results show that the maximum SERS enhancement, as estimated here as the fourth power of the local electric field, increases by a factor of 100 when the gap goes from 2 to 1 nm, reaching values as large as 10(10), strengthening the usage of electrophoresis versus diffusion for the development of molecular sensors

Graphene Plasmon Waveguiding and Hybridization in Individual and Paired Nanoribbons

Plasmons in doped graphene exhibit relatively large confinement and long lifetime compared to noble-metal plasmons. Here, we study the propagation properties of plasmons guided along individual and interacting graphene nanoribbons. Besides their tunability via electrostatic gating, an additional handle to control these excitations is provided by the dielectric environment and the relative arrangement of the interacting waveguides. Plasmon interaction and hybridization in pairs of neighboring aligned ribbons are shown to be strong enough to produce dramatic modifications in the plasmon field profiles. We introduce a universal scaling law that considerably simplifies the analysis an understanding of these plasmons. Our work provides the building blocks to construct graphene plasmon circuits for future compact plasmon devices with potential application to optical signal processing, infrared sensing, and quantum information technology