Being the polymorphs of calcium carbonate (CaCO3), vaterite and calcite have attracted a great deal of attention as promising biomaterials for drug delivery and tissue engineering applications. ...Furthermore, they are important biogenic minerals, enabling living organisms to reach specific functions. In nature, vaterite and calcite monocrystals typically form self-assembled polycrystal micro- and nanoparticles, also referred to as spherulites. Here, we demonstrate that alpine plants belonging to the Saxifraga genus can tailor light scattering channels and utilize multipole interference effect to improve light collection efficiency via producing CaCO3 polycrystal nanoparticles on the margins of their leaves. To provide a clear physical background behind this concept, we study optical properties of artificially synthesized vaterite nanospherulites and reveal the phenomenon of directional light scattering. Dark-field spectroscopy measurements are supported by a comprehensive numerical analysis, accounting for the complex microstructure of particles. We demonstrate the appearance of generalized Kerker condition, where several higher order multipoles interfere constructively in the forward direction, governing the interaction phenomenon. As a result, highly directive forward light scattering from vaterite nanospherulites is observed in the entire visible range. Furthermore, ex vivo studies of microstructure and optical properties of leaves for the alpine plants Saxifraga “Southside Seedling” and Saxifraga Paniculata Ria are performed and underline the importance of the Kerker effect for these living organisms. Our results pave the way for a bioinspired strategy of efficient light collection by self-assembled polycrystal CaCO3 nanoparticles via tailoring light propagation directly to the photosynthetic tissue with minimal losses to undesired scattering channels.
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IJS, KILJ, NUK, PNG, UL, UM
Abstract
The state of the art in optical biosensing is focused on reaching high sensitivity at a single wavelength by using any type of optical resonance. This common strategy, however, disregards ...the promising possibility of simultaneous measurements of a bioanalyte’s refractive index over a broadband spectral domain. Here, we address this issue by introducing the approach of in-fibre multispectral optical sensing (IMOS). The operating principle relies on detecting changes in the transmission of a hollow-core microstructured optical fibre when a bioanalyte is streamed through it via liquid cells. IMOS offers a unique opportunity to measure the refractive index at 42 wavelengths, with a sensitivity up to ~3000 nm per refractive index unit (RIU) and a figure of merit reaching 99 RIU
−1
in the visible and near-infra-red spectral ranges. We apply this technique to determine the concentration and refractive index dispersion for bovine serum albumin and show that the accuracy meets clinical needs.
Mesoscopic photonic systems with tailored optical responses have great potential to open new frontiers in implantable biomedical devices. However, biocompatibility is typically a problem, as ...engineering of optical properties often calls for using toxic compounds and chemicals, unsuitable for in vivo applications. Here, a unique approach to biofriendly delivery of optical resonances is demonstrated. It is shown that the controllable infusion of gold nanoseeds into polycrystalline sub‐micrometer vaterite spherulites gives rise to a variety of electric and magnetic Mie resonances, producing a tuneable mesoscopic optical metamaterial. The 3D reconstruction of the spherulites demonstrates the capability of controllable gold loading with volumetric filling factors exceeding 28%. Owing to the biocompatibility of the constitutive elements, “golden vaterite” paves the way to introduce designer‐made Mie resonances to cutting‐edge biophotonic applications. This concept is exemplified by showing efficient laser heating of gold‐filled vaterite spherulites at red and near‐infrared wavelengths, highly desirable in photothermal therapy, and photoacoustic tomography.
A mesoscopic biofrendly metamaterial, which includes a sub‐micrometer vaterite spherulite infiltrated with gold nanoseeds, is presented. Highly controllable gold loading leads to a variety of electric and magnetic Mie resonances, covering first and second biological transparency windows 700–1300 nm. The great potential for biophotonic applications is exemplified by demonstration of efficient spherulites laser heating at red and near‐infrared wavelengths.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Semiconductor nanowires exhibit numerous capabilities to advance the development of future optoelectronic devices. Among the III-V material family, gallium phosphide (GaP) is an attractive platform ...with low optical absorption and high nonlinear susceptibility, making it especially promising for nanophotonic applications. However, investigation of single nanostructures and their waveguiding properties remains challenging owing to typically planar experimental arrangements. Here we study the linear and nonlinear waveguiding optical properties of a single GaP nanowire in a special experimental layout, where an optically trapped structure is aligned along its major axis. We demonstrate efficient second harmonic generation in individual nanowires and unravel phase matching conditions, linking between linear guiding properties of the structure and its nonlinear tensorial susceptibility. The capability to pick up single nanowires, sort them with the aid of optomechanical manipulation and accurately position pre-tested structures opens a new avenue for the generation of optoelectronic origami-type devices.
An optically trapped single GaP nanowire is studied here. Optomechanical manipulation allows aligning the wire along its major axis and probes the linear waveguiding properties and nonlinear optical response of the standalone nanostructure.
Abstract
Semiconductor nanowires (NWs) offer multiple advantages for designing novel optoelectronic devices, such as small footprint, high quantum efficiency, high nonlinear susceptibility. Gallium ...phosphide (GaP) is one of the attractive materials owing to its low optical absorption and high nonlinear susceptibility. However NWs should be transferred to planar substrates for optical studies, which do not allow efficient signal outcoupling. We demonstrate efficient second harmonic generation in individual GaP nanowires trapped using optical tweezers. Such vertically arranged configuration of NW allows to both efficiently generate second harmonic and to probe linear optical response using broadband light source. Such experiment allows to examine interplay between harmonic generation efficiency and NW dimensions.
The article deals with the issues of repair of electro-hydraulic nozzles (EHN), which are widespread in automotive and tractor diesel engines. The actual resource of the EHN is significantly lower ...than the declared one and its restoration by carrying out repair and maintenance operations is expedient, both from a technical and economic point of view. The analysis of typical EHN malfunctions shows that one of the most wear-out elements of EHN is the contact surface of the seat of a ball electromagnetic valve. Typical and alternative technologies for repairing a valve seat are considered and a method for improving them with a vibration hardening of the contact surface is proposed. The goal and objectives of research are formulated. The theoretical substantiation of the process of vibration hardening of the EHN ball valve seat and its laboratory and bench studies, the results of which confirmed the working hypothesis about the possibility of forming a vibration rivet hardened contact surface of the valve, were carried out. The application of the proposed method will increase the resource of the repaired injectors at low costs for its implementation.
Structured environments are employed in a plethora of applications to tailor dynamics of light–matter interaction processes by modifying the structure of electromagnetic fields. The promising example ...of such a system is antiresonant photonic crystal fibers (AR-PCFs), which allow light–analyte interactions in a very long channel. Here we probe contribution of microstructuring and nontrivial mode hierarchy on light–matter interactions in AR-PCFs by investigating lifetime shortening of perovskite (
CsPbBr
3
) nanocrystals grown to fiber capillaries. The crystals have been deposited using a wet chemistry approach and then excited by a supercontinuum source in the 450–500 nm range. Emission spectra have been measured and analyzed via the time-correlated single photon counting (TCSPC) technique, unravelling contributions of core and cladding modes. Fluorescence lifetime imaging inside an AR-PCF enables mapping input of various electromagnetic channels into light–matter interaction processes. Our results pave the way for tailoring the dynamics of high-order quantum processes, promoting the concept of AR-PCF as a light-driven reactor.
Background: Overcoming of ecological crisis requires formation such human consciousness, such attitude to Nature and Human (i.e. to yourself and other people) based on awareness that human isn't ...against nature. The article there is a problem between that the child must have already formed structural identity, ecological consciousness, defining nature of relationships between human and the world, it is a resource of knowledge about process of development of ecological units and its structural constituent among preschoolers as a part of ecological culture of a person. Methods of the research: Leading method of the study of this issue is diagnostic, which allows considering this theme as a dynamic process. There are methods that was used during the process of the research: study of scientific and regulatory resources, ascertaining psycho-pedagogical experiment, analysis and synthesis of psycho-pedagogical experience, socio-psychological diagnostics: quiz, questioning, interview, observation, testing, expert review; psychodiagnostic methodologies; mathematical, statistical methods and methods of computer data processing. Results: Consists in theoretical and experimental research of features of children ecological consciousness, character settings in preschool age. The authors identified and substantiated the ecological consciousness is considered as a core of child personality, characterizing by subjectiveintegrative essence: complex of new growths, common for preschool childhood, ecological aims, and ecological idea, its inner component provides further self-development of personality, and external - acts, deeds of a child in real life. Conclusion: There are results of the study of children ecological consciousness for environmental protection settings at preschool age in urban and rural kindergarten in this work. It is necessary to base on leading structural component of ecological installation during the work with preschoolers and namely on affective. Taking this type as dominant, we will use preschoolers' ecological attitude as structural component of ecological installation of personality. Also it is necessary to consider the fact that preschoolers are ready to active acts for environmental protection. They can't wait to take part in different events. This desire and development of behavior component must be considered, evolving ecological setting of preschoolers and ecological consciousness at all.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
A compact pulsed mid-IR source with 10-ns pulsewidth, few hundred-microjoule energy, and repetition rate adjustable from 10 through 500 kHz is reported. In order to reach up to 30-% efficiency of ...down-conversion from 1064 nm to 1500/3500 nm, a 1064-nm narrow-line master oscillator is followed by a two-stage fiber amplifier. In turn, this amplifier is spliced with a large-mode-area photonic crystal fiber to ensure high quality of the beam that pumps a 5-mm thick periodically poled MgO-doped lithium niobate. The spectrum of the device replicates that of a cw 1500-nm seed laser.
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