White light emission from polystyrene under pulsed ultra violet laser irradiation.
Ontology highlight
ABSTRACT:
SUBMITTER: Kim E
PROVIDER: S-EPMC3832854 | biostudies-other | 2013
REPOSITORIES: biostudies-other
Similar Datasets
Project description:In this study, a novel photoluminescent quantum dots device with laser-processed microscale patterns has been demonstrated to be used as a white light emitting source. The pulsed laser ablation technique was employed to directly fabricate microscale square holes with nano-ripple structures onto the sapphire substrate of a flip-chip blue light-emitting diode, confining sprayed quantum dots into well-defined areas and eliminating the coffee ring effect. The electroluminescence characterizations showed that the white light emission from the developed photoluminescent quantum-dot light-emitting diode exhibits stable emission at different driving currents. With a flexibility of controlling the quantum dots proportions in the patterned square holes, our developed white-light emitting source not only can be employed in the display applications with color triangle enlarged by 47% compared with the NTSC standard, but also provide the great potential in future lighting industry with the correlated color temperature continuously changed in a wide range.
| S-EPMC4804257 | biostudies-literature
Project description:The interaction of fluorophores with nearby metallic structures is now an active area of research. Dielectric photonic structures offer some advantages over plasmonic structures, namely small energy losses and less quenching. We describe a dielectric one-dimensional photonic crystal (1DPC), which supports Bloch surface waves (BSWs) from 280 to 440 nm. This BSW structure is a quartz slide coated with alternating layers of SiO2 and Si3N4. We show that this structure displays BSWs and that the near-UV fluorophore, 2-aminopurine (2-AP), on the top surface of the structure couples with the BSWs. Fluorophores do not have to be inside the structure for coupling and show a narrow angular distribution, with an angular separation of wavelengths. The Bloch wave-coupled emission (BWCE) radiates through the dielectric layer. These BSW structures, with useful wavelength range for detection of intrinsic protein and cofactor fluorescence, provide opportunities for novel optical configurations for bioassays with surface-localized biomolecules and for optical imaging using the coupled emission.
| S-EPMC5512112 | biostudies-literature
Project description:Displaying a full or tuneable emission spectrum with highly efficient is significant for luminescent materials used in solid-state lighting. Silicon carbide (SiC) has potential for use in photoelectric devices that operate under extreme conditions. In this paper, we present a method to selectively modify the photoluminescence (PL) properties of SiC by ultrafast laser direct writing. Based on this method, visible white PL could be observed by the naked eye at room temperature under ultraviolet excitation. By increasing the laser power intensity from 40 to 80 MW/cm2, the PL of the irradiated samples increased and pure white sunlight-like emission with controlled colour temperature was realised. The optimised laser power intensity of 65 MW/cm2 achieved a desirable colour temperature similar to that of sunlight (x = 0.33, y = 0.33 and colour temperature of 5500 K) and suppressed blue emission. By direct laser irradiation along designed scanning path, a large-scale and arbitrary pattern white emission was fabricated. The origin of the white luminescence was a mixture of multiple luminescent transitions of oxygen-related centres that turned the Si-C system into silicon oxycarbide. This work sheds light on new luminescent materials and a preparation technique for next-generation lighting devices.
| S-EPMC5762700 | biostudies-literature
Project description:Analysis of accumulation of repair and checkpoint proteins at repair sites in yeast nuclei has conventionally used chemical agents, ionizing radiation or induction of endonucleases to inflict localized damage. In addition to these methods, similar studies in mammalian cells have used laser irradiation, which has the advantage that damage is inflicted at a specific nuclear region and at a precise time, and this allows accurate kinetic analysis of protein accumulation at DNA damage sites. We show here that it is feasible to use short pulses of near-infrared laser irradiation to inflict DNA damage in subnuclear regions of yeast nuclei by multiphoton absorption. In conjunction with use of fluorescently-tagged proteins, this allows quantitative analysis of protein accumulation at damage sites within seconds of damage induction. PCNA accumulated at damage sites rapidly, such that maximum accumulation was seen approximately 50 s after damage, then levels declined linearly over 200-1000 s after irradiation. RPA accumulated with slower kinetics such that hardly any accumulation was detected within 60 s of irradiation, and levels subsequently increased linearly over the next 900 s, after which levels were approximately constant (up to ca. 2700 s) at the damage site. This approach complements existing methodologies to allow analysis of key damage sensors and chromatin modification changes occurring within seconds of damage inception.
| S-EPMC4237433 | biostudies-literature
Project description:3 day of fifth instar larvae were treated with ultra-violet (UV) rays using UVL-56 (1350?W/cm2, UVP) for 6 and 12 hours (29.2 and 58.32 J/cm2). Since, larvae of each group rare on artificial diet for 24 hour and dissected fatbody. We examined gene expression profile in these groups. Gene expression was measured in 3 day of fifth instar larvae of ultra violet irradiation.
2015-02-26 | E-GEOD-55816 | biostudies-arrayexpress
Project description:3 day of fifth instar larvae were treated with ultra-violet (UV) rays using UVL-56 (1350μW/cm2, UVP) for 6 and 12 hours (29.2 and 58.32 J/cm2). Since, larvae of each group rare on artificial diet for 24 hour and dissected fatbody. We examined gene expression profile in these groups.
2015-02-26 | GSE55816 | GEO
Project description:Plasmonic nanostructures are of great current interest as chemical sensors, in vivo imaging agents, and for photothermal therapeutics. We study continuous-wave (cw) and pulsed-laser excitation of aqueous suspensions of Au nanorods as a model system for secondary light emission from plasmonic nanostructures. Resonant secondary emission contributes significantly to the background commonly observed in surface-enhanced Raman scattering and to the light emission generated by pulsed-laser excitation of metallic nanostructures that is often attributed to two-photon luminescence. Spectra collected using cw laser excitation at 488 nm show an enhancement of the broad spectrum of emission at the electromagnetic plasmon resonance of the nanorods. The intensity of anti-Stokes emission collected using cw laser excitation at 785 nm is described by a 300 K thermal distribution of excitations. Excitation by subpicosecond laser pulses at 785 nm broadens and increases the intensity of the anti-Stokes emission in a manner that is consistent with electronic Raman scattering by a high-temperature distribution of electronic excitations predicted by a two-temperature model. Broadening of the pulse duration using an etalon reduces the intensity of anti-Stokes emission in quantitative agreement with the model. Experiments using a pair of subpicosecond optical pulses separated by a variable delay show that the timescale of resonant secondary emission is comparable to the timescale for equilibration of electrons and phonons.
| S-EPMC3903255 | biostudies-literature
Project description:Recently, a growing amount of effort has been devoted to solving the widespread problem of pollution. Photocatalysts have attracted increasing attention for their widespread environmental applications. Here, a classic and simple electrospun technique is used to directly fabricate a porous a tungsten oxide nanoframework with graphene film as a photocatalyst for degradation of pollutants. The as-synthesized film simultaneously possesses substantial adsorptivity of aromatic molecules, extensive light absorption range, significant light trapping, and efficient charge carrier separation properties, which remarkably enhance photocatalytic activity. In the photodegradation of Rhodamine B, a significant photocatalytic enhancement in the reaction rate is observed, which has superior photocatalytic activity compared to other bare WO3 and TiO2 nanomaterials under visible-light irradiation.
| S-EPMC5115303 | biostudies-literature
Project description:Oral microbiome dysbiosis has important links to human health and disease. Although photodynamic therapy influences microbiome diversity, the specific effect of violet light irradiation remains largely unknown. In this study, we analyzed the effect of violet light-emitting diode (LED) irradiation on interdental plaque microbiota. Interdental plaque was collected from 12 human subjects, exposed to violet LED irradiation, and cultured in a specialized growth medium. Next-generation sequencing of the 16S ribosomal RNA genes revealed that α-diversity decreased, whereas β-diversity exhibited a continuous change with violet LED irradiation doses. In addition, we identified several operational taxonomic units that exhibited significant shifts during violet LED irradiation. Specifically, violet LED irradiation led to a significant reduction in the relative abundance of Fusobacterium species, but a significant increase in several species of oral bacteria, such as Veillonella and Campylobacter. Our study provides an overview of oral plaque microbiota changes under violet LED irradiation, and highlights the potential of this method for adjusting the balance of the oral microbiome without inducing antibiotic resistance.
| S-EPMC8614803 | biostudies-literature
Project description:A new graphene-based composite structure, monolayer-ordered macroporous film composed of a layer of orderly arranged macropores, was reported. As an example, SnO2-reduced graphite oxide monolayer-ordered macroporous film was fabricated on a ceramic tube substrate under the irradiation of ultra-violet light (UV), by taking the latex microsphere two-dimensional colloid crystal as a template. Graphite oxide sheets dispersed in SnSO4 aqueous solution exhibited excellent affinity with template microspheres and were in situ incorporated into the pore walls during UV-induced growth of SnO2. The growing and the as-formed SnO2, just like other photocatalytic semiconductor, could be excited to produce electrons and holes under UV irradiation. Electrons reduced GO and holes adsorbed corresponding negative ions, which changed the properties of the composite film. This film was directly used as gas-sensor and was able to display high sensitivity in detecting ethanol gas. More interestingly, on the basis of SnO2-induced photochemical behaviours, this sensor demonstrated tunable sensitivity when UV irradiation time was controlled during the fabrication process and post in water, respectively. This study provides efficient ways of conducting the in situ fabrication of a semiconductor-reduced graphite oxide film device with uniform surface structure and controllable properties.
| S-EPMC4355683 | biostudies-other