Deoxyribonucleic acid-based photochromic material for fast dynamic holography

The authors report on a biopolymeric material made of deoxyribonucleic acid (DNA) complexed with the cationic surfactant cetyltrimethyl-ammonium (CTMA) and doped with the photochromic disperse red 1 dye (DR1) for dynamic holographic recording. The molar ratio of the DNA-CTMA to the dye is about 5:1. They have found that the photochromic properties of DR1 in the DNA-CTMA matrix are favorably modified in speed of response with respect to conventional polymeric matrices. Dynamic holographic gratings which were inscribed in DR1:DNA-CTMA films are characterized by switching times within a 1–10ms range. An excellent reversibility of the recording process is reported.The authors acknowledge the Australian Research Council Discovery Project No. DP0556942, the Materials and Manufacturing Directorate Air Force Office of Scientific Research, the AOARD Grant No. 05-4010, and the Polish Ministry of Science and Higher Education Grant No. N50713231/3302 for financial support

Interplay of Stimulated Emission and Fluorescence Resonance Energy Transfer in Electrospun Light-Emitting Fibers

Concomitant amplified spontaneous emission (ASE) and F\"orster resonance energy transfer (FRET) are investigated in electrospun light-emitting fibers. Upon dye-doping with a proper FRET couple system, free-standing fibrous mats exhibit tunable FRET efficiency and, more importantly, tailorable threshold conditions for stimulated emission. In addition, effective scattering of light is found in the fibrous material by measuring the transport mean free path of photons by coherent backscattering experiments. The interplay of ASE and FRET leads to high control in designing optical properties from electrospun fibers, including the occurrence of simultaneous stimulated emission from both donor and acceptor components. All tunable-optical properties are highly interesting in view of applying electrospun light-emitting materials in lightening, display, and sensing technologies.Comment: 32 pages, 13 figure

"Siihen se tarina loppuu" Osallisuuden tukeminen saduttamalla

Opinnäytetyö oli toiminnallinen opinnäytetyö, jonka tavoitteena oli osallisuuden tukeminen sadutusmenetelmää hyödyntäen ja työn tarkoituksena oli myös tuottaa satukirja lasten kertomista saduista. Opinnäytetyö toteutettiin yhteistyössä päiväkoti Touhula Kangasalan kanssa kevään 2018 aikana. Työn tietoperusta koostui sadutuksesta, osallisuudesta, lasten kuulluksi tulemisesta, sekä varhaiskasvatuksesta. Opinnäytetyön toiminnallisessa osuudessa yksilösadutettiin lapsia ja näistä saduista koottiin työn liitteissä oleva satukirja. Lapset saivat kuvittaa omat satunsa ja kuvat liitettiin osaksi satukirjaa. Toiminnallinen osuus toteutettiin huhtikuussa 2018 ja sen aikana sadutettiin seitsemää 4-5-vuotiasta lasta. Työn tilaaja sai opinnäytetyön aikana syntyneen satukirjan jaettavaksi toiminnalliseen osuuteen osallistuneille lapsille. Lapset saivat antaa palautetta valmiista satukirjasta ja palaute heiltä oli positiivista. Lisäksi työ auttoi tukemaan lasten osallisuutta saduttamisen yhteydessä sekä opinnäytetyö toivottavasti innosti päiväkodin henkilökuntaa käyttämään sadutusmenetelmää myös tulevaisuudessa.This Bachelor’s thesis was practice-based and the aim was to support inclusion in the daycare centre Touhula in Kangasala by using the storycrafting method. Another goal was to make a storybook from the stories the children told. The thesis was implemented in spring 2018. The theoretical background consists of the storycrafting method, inclusion, what being heard is and early childhood education. In the practice part of the thesis, seven children aged four to five attended individual storycrafting sessiona. The children drew pictures to their stories and the stories were collected into a storybook. This practice part was carried out in April 2018. The Touhula Kangasala daycare centre received the finished storybook in May 2018. The children who took part into the storycrafting, also received copies of the storybook. The children also gave feedback about the book. The feedback was positive and the main aim of the thesis, to support the inclusion in the group, was achieved. The thesis also hopefully inspired the personnel to use the storycrafting method in the future

Non-Linear Optical Effects in Nanomaterials

Nonlinear optics is the domain of optics that studies the physical interaction between one or multiple optical beams of high intensity and an optical medium [...

Organic materials for lasing and processing of optical information

International audienc

Plasmonic Nanoparticles Driven Enhanced Light Amplification in a Local 2D and 3D Self-Assembly

We present fluorescence and a random lasing enhancement effect due to the interaction between gold nanoparticles (AuNPs) and Rhodamine 6G (Rh6G) dye. Non-covalently bounded dyes in the proximity of nanoparticles are studied in three systems of varying dimensionality: from (i) three-dimensional freely distributed suspensions, through (ii) quasi-two-dimensional multilamellar liposomes, to (iii) solid two-dimensional thin layers. Liposomes facilitate the formation of stable AuNPs/Rh6G composition showing enhanced fluorescence, while solid thin films exhibit plasmon-assisted random lasing

All-optical switching in dye-doped DNA nanofibers

All-optical switches are introduced which are based on deoxyribonucleic acid (DNA) in the form of electrospun fibers, where DNA is semi-intercalated with a push-pull, luminescent nonlinear pyrazoline derivative. Optical birefringence is found in the organic nanofibers, with fully reversible switching controlled through continuous-wave laser irradiation. The photoinduced signal is remarkably large, with birefringence highlighted by optically-driven refractive index anisotropy approaching 0.001. Sub-millisecond characteristic switching times are found. Integrating dye-intercalated DNA complex systems in organic nanofibers, as a convenient and efficient approach to template molecular organization and control it by external stimuli, might open new routes for realizing optical logic gates, reconfigurable photonic networks and sensors through physically-transient biopolymer components

Applications of low molecular liquid crystalline derivatives of azobenzene

International audienc

Photoinduced Birefringence in PMMA Polymer Doped with Photoisomerizable Pyrazoline Derivative

Upon S₀–S₁ excitation, the pyrazoline derivative molecule (<i>Z</i>)-2-(4-nitrophenyl)-3-(1-phenyl-4,5-dihydro-1<i>H</i>-pyrazol-3-yl)­acrylonitrile, abbreviated as PY-oCNNO₂, can be transformed from its ground state <i>trans</i> (<i>E</i>) form to bended <i>cis</i> (<i>Z</i>) form. Similar to the case of the well-known family of the photochromic azobenzenes, such a molecular property can be employed to fabrication of photochromic polymers by suitable doping of the chromophores into polymer matrix. In this work, we prepared poly­(methyl methacrylate) thin films doped with PY-oCNNO₂ and measured the characteristic for optical switchers dynamic and static photoinduced birefringence (PIB) phenomenon. Possible conformational states of PY-oCNNO₂, energy barriers, and associated dipole moments were calculated using TD-DFT quantum chemical methods. The presented experiments show that pyrazoline derivatives constitute a prospective group of materials with a great potential for photonic applications

Perylene-Based Chromophore as a Versatile Dye for Light Amplification

One of the challenges for modern optoelectronics is to find versatile, easily adaptable components for novel laser-based technologies. A very attractive perylene-derivative chromophore in different organic matrices for high-performance light amplification is discussed and outlined. Our approach demonstrates the outstandingly compatible laser dye and a viable strategy to provide an effective optical gain for stimulated emission enhancement. Through structural control, we produce simple optical devices embedded in organic matrices, such as poly(methyl methacrylate), nematic liquid crystalline (NLC) mixture, and a hybrid emulsion system (poly(vinyl alcohol) PVA + NLC mesophase). Importantly, we investigate and compare the spectroscopy of differently constructed organic systems in terms of stimulated-emission thresholds and light amplification process efficiency. Moreover, we report the effects of tunability for LC cells by an applied external electric field stimulus. Future directions of laser systems are outlined with an emphasis on the role of the perylene derivative. The studies meet current challenges in the field of modern organic technologies dedicated to various optoelectronic systems, including touch screens, displays, and Li-Fi networks