Blue Range Research Articles

Focus on lasers, imaging, and microscopy

Focus on lasers, imaging, and microscopy

Effect of evening light exposure on sleep in bipolar disorder: A longitudinal analysis for repeated measures in the APPLE cohort.

Sleep disturbance, a core feature of bipolar disorder, is associated with residual mood symptoms, mood episode recurrence and suicide ideation. We investigated the effect of evening light exposure on sleep in patients with bipolar disorder. In this longitudinal analysis, we measured the sleep parameters of 207 outpatients with bipolar disorder using actigraphy at their homes for seven consecutive nights. We measured the white-light illuminance and the irradiance of each wavelength during the 4 hours before each participant's bedtime. We used mixed-effect linear regression analysis for repeated measures to evaluate the effect of evening light exposure on subsequent sleep parameters. The median white-light illuminance was 25.8 lux (interquartile range, 12.9-50.1 lux). In a multivariable model adjusted for potential confounders, we found higher white-light illuminance to be significantly associated with lower sleep efficiency (per log lux: 95% confidence interval = [-1.328, -0.133]; p = 0.017), prolonged sleep-onset latency (95% confidence interval = [0.006, 0.172]; p = 0.035) and longer wake after sleep onset (95% confidence interval = [1.104, 4.459]; p = 0.001). This effect size was larger in the younger age group (aged < 44 years) stratified by median age. Higher irradiance of the blue wavelength range was significantly associated with longer wake after sleep onset, a result similar to those for the green and red wavelength ranges. We observed significant associations between evening light exposure and subsequent sleep in patients with bipolar disorder. The effects of various light wavelengths on sleep in bipolar disorder require further investigation.

Gold Nanorods for LSPR Biosensing: Synthesis, Coating by Silica, and Bioanalytical Applications.

Nanoparticles made of coinage metals are well known to display unique optical properties stemming from the localized surface plasmon resonance (LSPR) phenomenon, allowing their use as transducers in various biosensing configurations. While most of the reports initially dealt with spherical gold nanoparticles owing to their ease of synthesis, the interest in gold nanorods (AuNR) as plasmonic biosensors is rising steadily. These anisotropic nanoparticles exhibit, on top of the LSPR band in the blue range common with spherical nanoparticles, a longitudinal LSPR band, in all respects superior, and in particular in terms of sensitivity to the surrounding media and LSPR-biosensing. However, AuNRs synthesis and their further functionalization are less straightforward and require thorough processing. In this paper, we intend to give an up-to-date overview of gold nanorods in LSPR biosensing, starting from a critical review of the recent findings on AuNR synthesis and the main challenges related to it. We further highlight the various strategies set up to coat AuNR with a silica shell of controlled thickness and porosity compatible with LSPR-biosensing. Then, we provide a survey of the methods employed to attach various bioreceptors to AuNR. Finally, the most representative examples of AuNR-based LSPR biosensors are reviewed with a focus put on their analytical performances.

Synthesis and Crystal-Chemical, Thermal, and Spectrochemical Properties of the Zn2 – 2xNi2xSiO4 Solid Solution with a Willemite Structure

It has been found that the isomorphic capacity of the Zn2 – 2xNi2xSiO4 solid solution with a willemite structure is 15 mol % Ni. The unit cell parameters of Zn2 – 2xNi2xSiO4 samples in the homogeneity range of the solid solution are nearly independent of the content of dopant х and are close to those of undoped Zn2SiO4. It has been shown that the melting point of Zn2 – 2xNi2xSiO4 decreases with an increase in х from 1512°С for х = 0 to 1455°С for х = 0.15. The UV-Vis absorption spectrum and color coordinates of Zn2 – 2xNi2xSiO4 correspond to the blue range, and the color intensity of the pigment increases with increasing nickel content.

Solid‐State Preparation and Luminescence Investigation of Rare Earth Iodide Carbodiimide Nitrides RE2I(CN2)N (RE = La, Gd) and LaI(CN2)

New rare earth iodide carbodiimide nitride compounds with the composition RE2I(CN2)N (RE = La, Gd) were successfully synthesized by multilateral solid‐state metathesis reaction from RE triiodides, LiN and Li2(CN2). The crystal structures of RE2I(CN2)N were refined from X‐ray powder diffraction data with the space group Cmmm. LaI(CN2) was prepared from a mixture of LaI3 and Li2(CN2). The crystal structure was determined by X‐ray single‐crystal diffraction on a colorless crystal with the orthorhombic space group Cmcm. The luminescence investigation of Ce3+‐doped LaI(CN2) was carried out by excitation at 390 nm and reveals a broad emission band in the blue range of the visible spectrum.

Nominal risk analysis of the blue light from LED luminaires in indoor lighting design

It is a common opinion that LEDs emit a very high amount of energy in the blue range, which could be potentially harmful to our visual tissues. This study focuses on the LED lamps used for interior lighting and was carried out base don the parameters of 15 LED lights collected by inspectors from the Consumer Council of Castilla la Mancha, Spain. The samples were acquired at random from various commercial establishments. The luminaires acquired in collaboration with the public administration can be placed in any workplace or home. The following is a study of the nominal risk of blue light. The results show that these LED luminaires comply with relevant regulations, and none of them pose a risk to the retina because they all belong to the risk-free group.

Two-Photon Excited Luminescence in Polyethylene and Polytetrafluoroethylene

Luminescence spectra of polytetrafluoroethylene (Teflon), a Teflon film, and a polyethylene film are registered in wide wavelength range under excitation by radiations with different wavelengths. For the first time, we detect two-photon-excited luminescence in polymers at low intensity of exciting light. In Teflon, we also register luminescence in the blue range under excitation by ruby laser pulses.

Temperature, Silicon Thickness and Intrinsic Length Influence on the Operation of Lateral SOI PIN Photodiodes

This work presents an analysis of the influence of the intrinsic length region (Li) and the thickness of the silicon film (tSi) on the performance of lateral thin-film SOI PIN photodiodes when illuminated by low wavelengths, in the blue and ultraviolet (UV) range. The experimental measurements performed with the wavelengths of 396 nm, 413 nm, and 460 nm in a temperature range of 100 K to 400 K showed that the optical responsivity of the SOI PIN photodetectors has larger dependence on the incident wavelength than on temperatures variation. Two-dimensional numerical simulations showed the same trends as the experimental results as a function of temperature and as a function of wavelength. Numerical simulations were used to investigate the responsivity and total quantum efficiency of PIN SOI photodetectors with intrinsic length region ranging from 5 µm to 30 µm and silicon film thickness ranging between 40 nm to 500 nm. From the results can be concluded that by properly choosing Li and tSi it is possible to optimize PIN SOI photodiodes performance for detecting specific wavelengths.

Over 11 % efficient eco-friendly kesterite solar cell: Effects of S-enriched surface of Cu2ZnSn(S,Se)4 absorber and band gap controlled (Zn,Sn)O buffer

Abstract For high efficiency kesterite Cu2ZnSn(S,Se)4 (CZTSSe) solar cell, CdS thin film was usually used as a buffer layer. However, due to the toxicity of Cd and pollution problems involved from the solution-based chemical bath deposition, eco-friendly high efficiency CZTSSe solar cell with Cd-free buffer is necessary. As an Cd-free buffer layer, we investigated (Zn,Sn)O (ZTO) film deposited by sputtering method. In order to achieve high power conversion efficiency, we controlled energy band gaps of CZTSSe absorber as well as ZTO buffer, which was required to optimize conduction band offset (CBO) between the absorber and the buffer and to increase open circuit voltage (Voc) and fill factor (FF). The CBO was optimized by controlling the band gap of ZTO. By varying the Sn/(Zn + Sn) ratio and its deposition temperature, band gap of ZTO was successfully adjusted. Experimental and computational calculation results showed that solar cell performance was strongly affected by the CBO between absorber and buffer. Besides CBO matching, larger band gap of ZTO improved short circuit current density (Jsc) with enhanced external quantum efficiency value in blue photon spectrum range. As an additional way to improve power conversion efficiency of solar cell, band graded CZTSSe absorber was developed by using spray-based two-step process. The sprayed CZTSSe film was engineered to have S-enriched surface, which makes surface band gap widened and surface passivated, and resultantly increases Voc, Jsc and fill factor (FF). By controlling band gaps of both CZTSSe absorber and ZTO buffer, we obtained 11.22% environment-friendly CZTSSe solar cell without MgF2 anti-reflection coating.

Magnetic Resonance Imaging Features of Early Knee Cartilage Injury in Athletes and Its Significance in Diagnosis

Objective: The objective is to study the application and significance of magnetic resonance imaging (MRI) in the diagnosis of early knee joint cartilage injury in athletes, so as to provide corresponding rehabilitation training. Method: The imaging manifestations of T2 mapping of patellar cartilage in athletes and healthy volunteers are studied. 32 national professional athletes are included. The imaging characteristics of T2 mapping pseudocolor images of normal patellar cartilage are analyzed. The image characteristics of early patellar cartilage injury in T2 mapping pseudocolor images are analyzed, and the comparison of cartilage injury between athletes and ordinary people, as well as the injury of left and right knee cartilage of athletes are obtained. Results: The average value of T2 (T2av) of right patellar cartilage of athletes is higher than that of left patellar cartilage, and there are significant differences. The average T2av of right patellar cartilage is slightly higher than that of left patellar cartilage in healthy volunteers, with no significant differences. With the increase of training years, the color scale of patellar cartilage gradually increases, from the surface to the deep layer. In addition, the damage is aggravated, the blue range is reduced, the green range is expanded, and some yellow areas appear, which are more mixed. The lateral area and deviation to lateral area of right patellar cartilage are more obvious, and the T2 value is increased. Conclusion: T2 mapping can reflect the early injury of articular cartilage sensitively, intuitively and quantitatively. Before the morphological changes, the changes of biochemical structure of degenerative articular cartilage can be found by T2 mapping, which can provide theoretical support for the detection of early injury of knee cartilage in athletes.

Wavelength-Specific Behavior of the Western Flower Thrips (Frankliniella occidentalis): Evidence for a Blue-Green Chromatic Mechanism.

The western flower thrips (Frankliniella occidentalis) is a serious pest in horticulture, feeding on leaf tissue and floral resources. Blue and yellow sticky traps are commonly used for monitoring and control in greenhouses. The mechanisms underlying the color preferences are largely unknown. The use of light-emitting diodes (LEDs) is a promising approach to increase the attractiveness of visual traps and to study the color choice behavior in insects. The color preferences of F. occidentalis were systematically investigated in a series of choice experiments with several LEDs from the ultraviolet (UV) and visible spectral range. Blue LEDs were most attractive, followed by green, while only a moderate attractiveness of UV was observed. Blue and green were identified as two separate attractive ranges. When light from blue and green LEDs was mixed, the attractiveness decreased compared to its single components. In conclusion, F. occidentalis exhibits two different wavelength specific behaviors towards blue and green. Compelling indications are provided that these behaviors are controlled by two photoreceptors maximally sensitive in the blue and green range with an inhibitory chromatic interaction between both. Since the known UV sensitive photoreceptor could be confirmed, a trichromatic photoreceptor setup is suggested for F. occidentalis. For advanced plant protection strategies, the results offer several opportunities to optimize monitoring or even develop mass trapping devices.

Synthesis, Photo- and Electroluminescent Properties of 7'-[7,10-Bis-(4'-fluorophenyl)fluoranthen-8-yl](9,9-didecyl)fluorene as a Promising Material for Blue Organic Light-Emitting Diodes

A new oligomeric fluorophore, which combines the advantage of polycyclic aromatic compounds and fluorene structures has been synthesized. The new compound shows necessary film-forming properties, is readily soluble in the majority of organic solvents and emits in the blue range of solar light with maximum at 465 nm. The compound has a rather high quantum yield and can serve as both the electroluminescent dopant and the conducting light-emitting matrix for designing completely soluble blue and white OLEDs by both inkjet printing and spin coating. The new oligomeric fluorophore is a promising example of highly fluorescent oligomer, rarely used class of materials, in contrast to polymers and small molecules. Such oligomers can be useful for future completely soluble OLEDs.

Post-consumer polymers (PCR) for color retention of delicatessen meats and elucidation of the light blocking mechanism

Increased light blocking properties of extruded films can be realized by sustainable, post-consumer recycled (PCR) polymers. This study elucidates the light blocking mechanism of these films within the ultraviolet-visible region (UV–Vis) via a novel optical measurement and electron microscopy analysis. A spectrometer and integrating sphere were mounted on a translational stage opposite a light source to measure the apparent absorbance as a function of distance. It was determined that a mixed scattering/reflection mechanism is present for virgin/PCR high density polyethylene (HDPE) blends with increased scattering in the ultraviolet and both scattering and reflection in the blue-visible. An electron microscopy study further suggests that the unique optical properties may be due to the well-dispersed nano-domains of aluminum, oxygen, and silica with increasing PCR content in addition to changes in crystalline domains reported previously. This inspired the application of the material as a light fixture filter for preserving light sensitive products. The preservation efficiency of light sensitive specimens under light emitting diode (LED) illumination was evaluated quantitatively (CIE L*a*b* color space) and qualitatively (digital imaging) as a function of time. Using roast beef as a model system, the maximum red color change (a*) of non-filtered roast beef specimens was realized approximately 55% faster than the filtered (Δa* = 7.1) in simulated retail display conditions. The improved color retention under filtered light can be attributed to increased light scattering across the blue wavelength range (440–485 nm) reducing light exposure near the maximum absorption band of myoglobin. Reduction of blue light exposure inhibits metmyoglobin production and meat discoloration. Data presented in this study suggest that PCR polymers can tune light blocking properties, providing a means to increase the color retention of light sensitive foods while simultaneously diverting food and plastic waste from landfills.

Luminescent down-shifting natural dyes to enhance photovoltaic efficiency of multicrystalline silicon solar module

The short wavelength photons (below 500 nm) of the solar spectrum are under-utilized in multicrystalline silicon (mc-Si) solar modules because of their high surface recombination losses. The application of luminescent down-shifting (LDS) materials is an effective way to utilize the short wavelength photons to enhance the efficiency of a mc-Si solar module. This study utilized four ‘natural’ dyes extracted from the wheat husk, rice husk, turmeric rhizomes (Curcuma longa L.), and Moringa Oleifera leaves for LDS application. These natural dyes showed absorption in the UV and blue range, and emission in the visible range which is effectively utilized by the silicon solar cell. Optimum concentrations of the natural dyes were incorporated in the front ethylene vinyl acetate (EVA) layers which were used to encapsulate bare Si cells into photovoltaic (PV) modules. The mc-Si PV modules which had the front encapsulation of EVA films containing the turmeric and moringa dyes showed relative enhancement of ~ 6.8% (±3.6) and ~ 9% (±4) respectively, in their efficiencies with respect to that of the corresponding bare silicon cells. The gains in the photovoltaic efficiency obtained with the turmeric and moringa dyes were found to be comparable to (or slightly greater than) the values reported in the literature using various Eu3+ based lanthanide complexes as LDS materials. Finally, the inclusion of natural LDS dyes in the encapsulating EVA layer would offer an economical and pro-environmental solution at high volume manufacturing to improve the utilization of short-wavelength photons.

Self-trapped-induced energy funneling and broadband emission in the Mn2+ doped two-dimensional perovskite

The electronic structure modulations by metal cation doping and organic ligands modification are aroused great interests in perovskite community for spectrum tailoring and quantum yield (QY) enhancement. Herein, we synthesized the two-dimensional (2D) lead bromide perovskite with cyclohexenylethylamine as the organic ammonium ligands and divalent manganese as the doping ions by the combination of facile solution processes and low temperature solid-state method. Thanks to the synergy effects of the steric-hindrance induced self-trapped exciton (STE) by A-site engineering and the elevation of cascaded energy funneling among the FE, STE and the 4T1→6A1 transition of Mn2+. The emission spectrum of the Mn2+ doped 2D perovskite simultaneously covers both the blue and orange range with a QY of 47.01%, where the value is about twelve times of that of the un-doped one at room temperature. Our results indicate that the utilizing of soft organic ammonium and Mn2+ doping in 2D perovskite could not only adjust the energy level states and improve the QY remarkably, but also explore new opportunities in warm-white LEDs and other applications.

Laser-Induced Periodic Ag Surface Structure with Au Nanorods Plasmonic Nanocavity Metasurface for Strong Enhancement of Adenosine Nucleotide Label-Free Photoluminescence Imaging.

The label-free detection of biomolecules by means of fluorescence spectroscopy and imaging is topical. The developed surface-enhanced fluorescence technique has been applied to achieve progress in the label-free detection of biomolecules including deoxyribonucleic acid (DNA) bases. In this study, the effect of a strong enhancement of photoluminescence of 5′-deoxyadenosine-monophosphate (dAMP) by the plasmonic nanocavity metasurface composed of the silver femtosecond laser-induced periodic surface structure (LIPSS) and gold nanorods or nanospheres has been realized at room temperature. The highest value of 1220 for dAMP on the Ag-LIPSS/Au nanorod metasurface has been explained to be a result of the synergetic effect of the generation of hot spots near the sharp edges of LIPSS and Au nanorod tips together with the excitation of collective gap mode of the cavity due to strong near-field plasmonic coupling. A stronger plasmonic enhancement of the phosphorescence compared to the fluorescence is achieved due to a greater overlap of the phosphorescence spectrum with the surface plasmon spectral region. The photoluminescence imaging of dAMP on the metasurfaces shows a high intensity in the blue range. The comparison of Ag-LIPSS/Au nanorod and Ag-LIPSS/Au-nanosphere metasurfaces shows a considerably higher enhancement for the metasurface containing Au nanorods. Thus, the hybrid cavity metasurfaces containing metal LIPSS and nonspherical metal nanoparticles with sharp edges are promising for high-sensitive label-free detection and imaging of biomolecules at room temperature.

Building multidisciplinary collaboration in coastal and ocean modelling and observation in Australasia

Australia has the third-largest ocean territory on Earth, with 85% of Australians living within 50 km of the coast. As a result, coasts and ocean matter to Australia and are integral to the use of marine resources for sustainable economic development, i.e. Australia's blue economy. The societal, economic and cultural issues associated with the blue economy range from marine sovereignty, safety and security to food and energy security, biodiversity conservation, management and coastal populations. Marine, climate and Antarctic science have the potential to drive the development of Australia's blue economy through the creation of new knowledge, tools, technology, and innovation. This requires observations from the past to the present, as well as numerical modelling capability that can hindcast, nowcast, and forecast the marine environment with skill.

Photobiomodulation of human osteoblast-like cells invitro by low-intensity-pulsed LED light.

Visible light irradiation is an emerging area in regenerative medicine research. We hypothesized that low‐intensity‐pulsed LED light irradiance may exert photobiomodulatory effects on cultured osteoblast‐like cells. To test this hypothesis, we investigated cell proliferation and markers of cell maturation and metabolic activity following pulsed LED irradiance. Monolayer explant cultures of human osteoblast‐like cells were exposed four times in 24‐h intervals to 2 min of pulsed white LED irradiance of 2.4–2.5 mW·cm−2 and its different spectra of 0.2–0.5 mW·cm−2 (frequency range of 10–40 Hz). Cell proliferation was estimated from microscopic cell counting and cell death by lactate dehydrogenase activity in culture media (measured by a colorimetric method). The early markers of osteoblast maturation and metabolic activity, that is, cellular alkaline phosphatase activity and osteocalcin content, were measured using a colorimetric method and ELISA, respectively. Irradiance of 40 Hz caused the highest increase in cell number (P < 0.01). Osteocalcin content in cells decreased following 40 Hz and 10 Hz irradiance (P < 0.05). The 40 Hz blue range irradiance (diffuse transmittance 420–580 nm, maximal cell irradiance 0.5 mW·cm−2) caused a decrease in alkaline phosphatase cellular activity (P < 0.001) and an increase in media osteocalcin content (P < 0.05). The 40 Hz green range (diffuse transmittance 560–650 nm, maximal cell irradiance 0.4 mW·cm−2) irradiance caused an increase in the number of cells and in cell death. In summary, pulsed (40 Hz) white light irradiance has photomodulatory effects, with its green range spectrum affecting cell proliferation and cell death, and its blue range spectrum affecting cellular maturation and metabolism. The results indicate a low‐intensity threshold of photobiomodulation of osteoblast‐like cells in vitro.

Anti-stress phytohormones impact on proteome profile of green gram (Vigna radiata) under salt toxicity

Anti-stress phytohormones impact on proteome profile of green gram (Vigna radiata) under salt toxicity

Luminescence-enhancement and tunable-excitation of far-red emitting La2LiSbO6:Mn4+, Bi3+ phosphors for plant growth lighting

In this paper, Bi3+ ions were co-doped into La2LiSbO6:Mn4+ phosphors for purpose of improving luminescent properties in the near ultraviolet and blue light range. A significant enhancement from 25.89% to 58.71% in quantum yield under blue light excitation was achieved. Impressively, via increasing Bi3+ concentration, the excitation spectra can be effectively tuned from double to triple bands along with the maximum excitation peak changed. Besides, particle morphology and Raman vibration modes were investigated to reveal the luminescence enhancement and the excitation evolution mechanisms. The results show that Bi3+-induced structure symmetry change may play a dominant role in tunable excitation phenomenon of the samples, which makes La2LiSbO6:Mn4+, Bi3+ may have a potential application in plant growth lighting LEDs for different kind of excitation light sources.