Blue-green Light Research Articles

Photochemistry of (Z)-Isovinylneoxanthobilirubic Acid Methyl Ester, a Bilirubin Dipyrrinone Subunit: Femtosecond Transient Absorption and Stimulated Raman Emission Spectroscopy.

Bilirubin (BR) is an essential metabolite formed by the catabolism of heme. Phototherapy with blue-green light can be applied to reduce high concentrations of BR in blood and is used especially in the neonatal period. In this work, we studied the photochemistry of (Z)-isovinylneoxanthobilirubic acid methyl ester, a dipyrrinone subunit of BR, by steady-state absorption, femtosecond transient absorption, and stimulated Raman spectroscopies. Both the (Z)- and (E)-configurational isomers of isovinylneoxanthobilirubic acid undergo wavelength-dependent and reversible photoisomerization. The isomerization from the excited singlet state is ultrafast (the lifetimes of (Z)- and (E)-isomers were found to be ∼0.9 and 0.1 ps, respectively), and its efficiencies increase with increased photon energy. In addition, we studied sensitized photooxidation of the dipyrrinone subunit by singlet oxygen that leads to the formation of propentdyopents. Biological activities of these compounds, namely, effects on the superoxide production, lipoperoxidation, and tricarboxylic acid cycle metabolism, were also studied. Finally, different photochemical and biological properties of this BR subunit and its structural analogue, (Z)-vinylneoxanthobilirubic acid methyl ester, studied before, are discussed.

Power allocation scheme in MIMO-OFDM UWOC system with varying receiver spacing channel gain analysis

Abstract For underwater blue–green light multiple-input multiple-output orthogonal frequency division multiplexing modulation system (MIMO-OFDM), the underwater MIMO channel gain matrix corresponding to the change of receiver spacing was analyzed and derived, and a proportional power allocation scheme combined with singular value decomposition (SVD) precoding was proposed, in order to eliminate inter-channel interferences of the MIMO system. The simulation results show that when the transmitter spacing is fixed, and the receivers adopt the same spacing as the transmitters, which is difficult to achieve in the complex underwater environment, the system bit error rate (BER) performance under the proposed proportional power allocation scheme is the same as that of the average power allocation. When the receiver spacing increases, the system BER under the proposed scheme can ensure better overall performance compared with that of the traditional average allocation scheme.

Multisite-occupation properties, spectral characteristics and energy-transfer behaviors of Ca2ZrSi4O12:Ce3+,Tb3+ phosphor for NUV-based LEDs

In this paper, the Ce3+- and Tb3+-activated Ca2ZrSi4O12 (CZSO) sample series were prepared by employing a solid-solid synthesis route at high temperatures. The phase composition and crystal structure of as-prepared phosphors were studied by x-ray diffraction (XRD). The ionic lattice occupation, photoluminescence properties, energy-transfer behaviors, decay time, and thermal stability were investigated systematically. With excitation of 322 nm, CZSO:0.01Ce3+ phosphor can produce an asymmetrical wide emission spectrum peaking at 382 nm, in which two types of emission centers (marked as Ce I and Ce Ⅱ) originated from Ce3+ occupying 9- and 8-coordinated Ca2+ sites have been identified and discussed. The Tb3+-activated CZSO phosphor can emit several narrow bands ranging from 350 to 650 nm, corresponding to the 5Di → 7Fj (i = 3, 4; j = 3, 4, 5, 6) transitions of Tb3+. With the strategy of Ce3+ → Tb3+energy transfer (ET), intense blue-green light has been obtained in CZSO:Ce3+, Tb3+ samples. The ET mechanism was confirmed as dipole-dipole interaction using the critical distance equation suggested by Dexter and Readeld. The internal quantum efficiency (IQE) and external quantum efficiency (EQE) of phosphor with optimum doping concentrations (CZSO:0.01Ce3+,0.045Tb3+) were calculated to be 59.2% and 32.7%, respectively. Furthermore, the ET process was verified to be dominated by Ce Ⅱ→Tb3+ through the analysis of spectra-shifting and lattice occupancy. The calculated chromaticity coordinates suggested by CIE can be adjusted from the blue position to the greenish-yellow region according to the variation of Tb3+ concentration. The experimental data indicate that the CZSO:Ce3+, Tb3+ phosphors have potential value for NUV-based LEDs.

Characterization of Blue-Green Light Non-Line-of-Sight Transmission in Seawater

The blue-green light in the 450 nm to 550 nm band is usually used in underwater wireless optical communication (UWOC). The blue-green light transmission in seawater is scattered by the seawater effect and can achieve communication in non-line-of-sight (NLOS) transmission mode. Compared to line-of-sight (LOS) transmission, NLOS transmission does not require alignment and can be adapted to various underwater environments. The scattering coefficients of seawater at different depths are different, which makes the scattering of light in different depths of seawater different. In this paper, the received optical power and bit error rate (BER) of the photodetector (PD) were calculated when the scattering coefficients of blue-green light in seawater vary from large to small with increasing depth for NLOS transmission. The results show that blue-green light in different depths of seawater in the same way NLOS communication at the same distance, the received optical power and BER at the receiver are different, and the received optical power of green light is greater than that of blue light. Increasing the forward scattering coverage of the laser will suppress the received optical power of the PD, so when performing NLOS communication, appropriate trade-offs should be made between the forward scattering coverage of the laser and the received optical power.

Far-red triplet sensitized Z-to-E photoswitching of azobenzene in bioplastics.

We report the first example of direct far-red triplet sensitized molecular photoswitching in a condensed phase wherein a liquid azobenzene derivative (Azo1) co-assembled within a liquid surfactant-protein film undergoes triplet sensitized Z-to-E photoswitching upon far-red/red light excitation in air. The role of triplet sensitization in photoswitching has been confirmed by quenching of sensitizer phosphorescence by Z-Azo1 and temperature-dependent photoswitching experiments. Herein, we demonstrate new biosustainable fabrication designs to address key challenges in solid-state photoswitching, effectively mitigating chromophore aggregation and requirement of high energy excitations by dispersing the photoswitch in the trapped liquid inside the solid framework and by shifting the action spectrum from blue-green light (450-560 nm) to the far-red/red light (740/640 nm) region.

Structural insights into blue-green light utilization by marine green algal light harvesting complex II at 2.78 Å

Light-harvesting complex II (LHCII) present in plants and green algae absorbs solar energy to promote photochemical reactions. A marine green macroalga, Codium fragile, exhibits the unique characteristic of absorbing blue-green light from the sun during photochemical reactions while being underwater owing to the presence of pigment-altered LHCII called siphonaxanthin–chlorophyll a/b-binding protein (SCP). In this study, we determined the structure of SCP at a resolution of 2.78 Å using cryogenic electron microscopy. SCP has a trimeric structure, wherein each monomer containing two lutein and two chlorophyll a molecules in the plant-type LHCII are replaced by siphonaxanthin and its ester and two chlorophyll b molecules, respectively. Siphonaxanthin occupies the binding site in SCP having a polarity in the trimeric inner core, and exhibits a distorted conjugated chain comprising a carbonyl group hydrogen bonded to a cysteine residue of apoprotein. These features suggest that the siphonaxanthin molecule is responsible for the characteristic green absorption of SCP. The replaced chlorophyll b molecules extend the region of the stromal side chlorophyll b cluster, spanning two adjacent monomers.

Short-wavelength light induces broiler’s behavioral and physiological syndrome through a misaligned eating rhythm

Previous work shows that long-wavelength light has a robust circadian rhythmic pattern in the expression of clock genes of chickens, whereas short-wavelength light leads to an arrhythmic oscillation of some clock genes (e.g., cClock, cCry1, cCry2, cPer2, and cPer3). However, knowledge about the consequences of LED lights on the physiological and behavioral phenotype was still not clear. This experiment hypothesizes that short-wavelength light disturbs chickens’ eating rhythm and leads to the wrong time to eat, resulting in metabolic syndrome. “Meihuang” broilers were housed in monochromatic LED blue light, green light, yellow light, red light, or white light with a very low dose (15 lx). Multiply physiological parameters were measured and the 24-h eating behavior was determined. The effects of LED light on physiological status and behavioral phenotype showed a wavelength-dependent manner. Short-wavelength light significantly decreased the level of total triglycerides and total cholesterol but increased triiodothyronine concentration. Inversely, long-wavelength light increased the triglycerides and total cholesterol and reduced the level of triiodothyronine. Further, it was found that short-wavelength light significantly boosted body weight compared with long-wavelength light, despite equivalent levels of food intake. Short-wavelength light-induced 23.4% and 14.1% of food consumption during subjective nights, but long-wavelength light did not. These results imply that when chickens eat matters, not just what they eat. Thus, low as 15 lx of blue light exposure during the typical dark period is sufficient to lead an individual to eat at the “wrong” time, causing metabolic dysfunction. Blue light should be cautiously considered to be used in the poultry breeding process. Keywords: short-wavelength light, broiler, behavior, physiology, environmental control, circadian rhythm, intermittent eating DOI: 10.25165/j.ijabe.20221503.6456 Citation: Yang Y F, Liu Q, Wang S Y, Zeng L, Pan C H, Jado A, et al. Short-wavelength light induces broiler’s behavioral and physiological syndrome through a misaligned eating rhythm. Int J Agric & Biol Eng, 2022; 15(3): 47–54.

Transcriptomic and Metabolomic Profiling Reveals the Effect of LED Light Quality on Fruit Ripening and Anthocyanin Accumulation in Cabernet Sauvignon Grape.

Different light qualities have various impacts on the formation of fruit quality. The present study explored the influence of different visible light spectra (red, green, blue, and white) on the formation of quality traits and their metabolic pathways in grape berries. We found that blue light and red light had different effects on the berries. Compared with white light, blue light significantly increased the anthocyanins (malvidin-3-O-glucoside and peonidin-3-O-glucoside), volatile substances (alcohols and phenols), and soluble sugars (glucose and fructose), reduced the organic acids (citric acid and malic acid), whereas red light achieved the opposite effect. Transcriptomics and metabolomics analyses revealed that 2707, 2547, 2145, and 2583 differentially expressed genes (DEGs) and (221, 19), (254, 22), (189, 17), and (234, 80) significantly changed metabolites (SCMs) were filtered in the dark vs. blue light, green light, red light, and white light, respectively. According to Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses, most of the DEGs identified were involved in photosynthesis and biosynthesis of flavonoids and flavonols. Using weighted gene co-expression network analysis (WGCNA) of 23410 highly expressed genes, two modules significantly related to anthocyanins and soluble sugars were screened out. The anthocyanins accumulation is significantly associated with increased expression of transcription factors (VvHY5, VvMYB90, VvMYB86) and anthocyanin structural genes (VvC4H, Vv4CL, VvCHS3, VvCHI1, VvCHI2, VvDFR), while significantly negatively correlated with VvPIF4. VvISA1, VvISA2, VvAMY1, VvCWINV, VvβGLU12, and VvFK12 were all related to starch and sucrose metabolism. These findings help elucidate the characteristics of different light qualities on the formation of plant traits and can inform the use of supplemental light in the field and after harvest to improve the overall quality of fruit.

Aligned polymer dispersed liquid crystal film for light enhancement of quantum dot backlight

Quantum dots (QDs) have been used to make backlight, which provides a superior color gamut, for liquid crystal flat panel displays. In the backlight system, quantum dots, embedded in a polymer film and illuminated by blue light, emit red and green light with narrow bandwidths. There is, however, a problem with the system in that the quantum dots emit light in all directions, and most of the emitted light is in directions with large incident angles and cannot exit the film due to the total internal reflection at the film-air interface and is wasted. We propose to use an aligned polymer dispersed liquid crystal (APDLC) film to reduce the total internal reflection in the QD backlight and thus improve the light efficiency. A regular PDLC film, where the embedded liquid crystal droplets are randomly oriented, exhibits isotropic scattering and is not a good candidate for the enhancement of light efficiency of QD backlight. Through a two-step polymerization, we successfully developed an aligned polymer dispersed liquid crystal (APDLC) film where the liquid crystal droplets are permanently unidirectionally aligned in the film’s normal direction. It exhibits selective scattering: it scatters light with large incident angles but not light with small incident angles. When the APDLC film is laminated on the QD backlight film, a significant enhancement of the light efficiency of the QD backlight is achieved. The APDLC film can also be used to increase the light efficiency of other flat panel displays, such as organic light emitting diode (OLED) display and micro-light emitting diode (MLED) display.

Study on the Joint Toxicity of Multi-component Mixtures of Quaternary Ammonium Compounds

Pollutants generally exist as mixtures in the environment. Their cumulative toxicity and toxicity interactions are potential risks. Therefore, this study aimed to examine the variation of joint toxicity of a multi-component mixture system, which consisted of six common quaternary ammonium salt surfactants in the environment, on Vibrio qinghaiensis sp.-Q67 (Q67). Vibrio qinghaiensis sp. -Q67 (Vqin-Q67) is a freshwater luminescent bacterium that continuously emits blue-green light (485 nm). The bacterium has been widely used for detecting toxic contaminants. In the mixture system, the luminescent toxicity of each component of the mixture to Q67 was determined by the microplate toxicity analysis method, and the toxicity interaction of the mixture was determined by the toxicity unit method (TU). The combined toxicity of the mixture system was investigated from four aspects, including the number of components, key components, concentration (toxicity) ratio, and exposure time. The results showed that the combined toxic effect of the same mixture system tends to be an additive effect with the increase of the number of components. The combined toxicity of the mixture system was close to that of the key components. Antagonism was presented in the equal toxicity mixture, while synergism was presented in the non-equal toxicity mixture. The combined toxic effect of the multi-component mixture system was not only related to the concentration of the pollutant but also related to the exposure time of the pollutant.

Combined Analysis of the Effects of Exposure to Blue Light in Ducks Reveals a Reduction in Cholesterol Accumulation Through Changes in Methionine Metabolism and the Intestinal Microbiota.

Monochromatic light is widely used in industry, medical treatment, and animal husbandry. Green-blue light has been found to stimulate the proliferation of satellite cells and the results of studies on the effects of blue light on poultry vary widely. It would be worthwhile to study the effect of blue light on poultry growth and how exposure to blue light affects metabolism and the intestinal microbiota. In this study, we irradiated Cherry Valley ducks with 460 nm wavelength light (blue light) for 3 weeks to explore the effects of blue light in comparison to those of white light (combined wavelength light) on animal growth and development. Our results showed that, under exposure to blue light, the body weight and average daily feed intake of ducks were decreased, but the leg muscle and relative length of the intestine were increased. Exposure to blue light chiefly enhanced the anti-inflammatory and antioxidant capacities of the animal and decreased lipid levels in serum and liver. Metabolomic analysis revealed that blue light heightened cysteine and methionine metabolism, and increased serum taurine and primary bile acid levels, as well as up-regulating the metabolites L-carnitine and glutamine. Treatment with blue light significantly increased the beta diversity of intestinal microbiota and the relative abundances of bile acid hydrolase-producing bacteria, especially Alistipes. These changes promote the synthesis of secondary bile acids to further enhance lipid metabolism in the host, thereby reducing cholesterol accumulation in ducks. These results should help us better understand the effects of exposure to blue light on metabolite levels and the intestinal microbiota, and suggest that it may be possible to use colored light to control the development of livestock and poultry.

Action spectrum of phototherapy in hyperbilirubinemic neonates.

Phototherapy with blue light matching plasma absorption spectrum of the bilirubin-albumin complex with peak at 460 nm is standard treatment of neonatal hyperbilirubinemia. To demonstrate clinically the action (efficacy) spectrum of phototherapy in hyperbilirubinemic neonates, through determination of the fraction of total serum bilirubin (TSB) decreased by phototherapy with peak emission wavelengths ≥478 nm (blue-green) compared with that of light of 459/452 nm (blue). TSB values were compiled from three earlier trials, in which hyperbilirubinemic neonates were randomized to receive 24 h of either blue-green light (478/490/497 nm) (intervention groups) or blue light (459/452/459 nm) (control groups) with equal irradiance and exposed body surface areas. Ratios (efficacy) between the decrease in TSB between intervention and control groups were calculated and graphed versus peak wavelengths, demonstrating the course of the action spectrum. Calculated efficacy ratios were 1.31, 1.18, and 1.04 for light with peak wavelengths of 478, 490, and 497 nm, respectively. The action spectrum increases from 452/459 to maximum at 478 nm, from where it decreases to 1.18 and finally to 1.04. For optimal phototherapeutic treatment, neonates need to be exposed to light with peak wavelength some 20 nm longer than is presently used. The action (efficacy) spectrum of phototherapy for hyperbilirubinemic neonates has its peak wavelength at 478 nm. The peak wavelength of this action spectrum is 20 nm longer than the wavelength presently believed to be most efficient. The peak is also different from the peak found in vitro. For optimal phototherapeutic effect, neonates need to be treated with light of wavelengths some 20 nm longer than are presently used.

Evaluating chronotypically tailored light therapy for breast cancer survivors: Preliminary findings on fatigue and disrupted sleep

ABSTRACT More than one-third of cancer survivors experience significant residual symptoms after treatment completion. Fatigue and sleep disruption often co-occur and exacerbate each other. The purpose of this preliminary analysis was to examine the effect of a chronotypically tailored light therapy on fatigue and sleep disruption in female survivors 1–3 years post-completion of chemotherapy and/or radiation for stage I to III breast cancer. The data for this analysis were collected as part of an ongoing two-group randomized controlled trial (NCT03304587). Participants were randomized to receive either bright blue-green light (experimental) or dim red light (control). Light therapy was self-administered using a light visor cap at home. Both groups received 30-min daily light therapy for 14 consecutive days either between 19:00 and 20:00 h (for morning chronotypes) or within 30 min of waking in the morning (for evening chronotypes). Fatigue and sleep quality were self-reported using the Patient-Reported Outcomes Measurement Information System (PROMIS)-Fatigue, PROMIS-Sleep Disturbance, Pittsburgh Sleep Quality Index, and a daily log before (pre-test) and following the light intervention (post-test). Linear mixed model analysis or generalized estimating equations examined group difference overtime adjusting for pre-test scores. No between-group differences were found. However, after adjusting for the baseline fatigue, the experimental group reported significant decreases in fatigue (p < .001) and sleep disturbance (p = .024) overtime. The experimental group also reported significantly better subjective sleep quality after 14 d of light therapy (p = .017). Positive trends in sleep latency, sleep duration, night-time awakenings, and early morning awakenings were also observed. Unexpectedly, sleep disturbance significantly decreased in the control group (p = .030). Those who received dim light control reported significantly shorter sleep latency (p = .002), longer total sleep time (p = .042), and greater habitual sleep efficiency (p = .042). These findings suggest that bright light therapy significantly improved post-treatment fatigue and subjective sleep quality in breast cancer survivors. Although it remains to be confirmed, the findings additionally show unexpected benefits of dim light on sleep. Properly timed light exposure may optimize the therapeutic effect and can be the key for successful light therapy. How the administration timing coupled with wavelengths (short vs. long) and intensity of light affecting fatigue and disrupted sleep requires further investigation.

DEVELOPING AN EFFECTIVE LOW COST BLUE-GREEN LED PHOTOTHERAPY METHOD FOR NEONATAL JAUNDICE TREATMENT

Jaundice is an unusual situation in neonatal toddlers and is a scientific signal of excess conjugated or unconjugated hyperbilirubinemia. Phototherapy is the maximum broadly used treatment, and it has proved safe and powerful for over recent years. Compact fluorescent tubes, halogen bulbs, fiber optic blankets, and LEDs are commonly used light sources for phototherapy with varying efficiencies. In recent years, there are several studies reported blue-green LED phototherapy to be effective than conventional phototherapy in term neonates. This research aimed to develop the effectiveness of bluegreen LED phototherapy with a larger illuminated area and higher irradiance to conventional phototherapy methods. This lamp device was built with a blue-green LED light source composed of a matrix of 15 x 25 LEDs that generates 460 nm. This device is characterized by being a very compact source with an effective low cost, long life and low energy consumption phototherapy method. The results obtained were comparable with industrially synthetic devices, but being self-made, it grew to become out to be less highly-priced, consequently greater efficient in terms of fitness costs. In this research work conclude that high intensity blue-green LED device was much more effective than conventional phototherapy methods for jaundice photo degradation. Further studies will be necessary to prove its clinical efficiency.

Phytoplankton Genera Structure Revealed from the Multispectral Vertical Diffuse Attenuation Coefficient

The composition of phytoplankton and the concentration of pigments in their cells make their absorption and specific absorption coefficients key parameters for bio-optical modeling. This study investigated whether the multispectral vertical diffuse attenuation coefficient of downward irradiance (Kd) gradients could be a good framework for accessing phytoplankton genera. In situ measurements of remote sensing reflectance (Rrs), obtained in an Amazon Floodplain Lake (Lago Grande do Curuai), were used to invert Kd, focusing on Sentinel-3/Ocean and Land Color Instrument (OLCI) sensor bands. After that, an analysis based on the organization of three-way tables (STATICO) was applied to evaluate the relationships between phytoplankton genera and Kd at different OLCI bands. Our results indicate that phytoplankton genera are organized according to their ability to use light intensity and different spectral ranges of visible light (400 to 700 nm). As the light availability changes seasonally, the structure of phytoplankton changes as well. Some genera, such as Microcystis, are adapted to low light intensity at 550–650 nm, therefore high values of Kd in this range would indicate the dominance of Microcysts. Other genera, such as Aulacoseira, are highly adapted to harvesting blue-green light with higher intensity and probably grow in lakes with lower concentrations of colored dissolved organic matter that highly absorbs blue light (405–498). These findings are an important step to describing phytoplankton communities using orbital data in tropical freshwater floodplains. Furthermore, this approach can be used with biodiversity indexes to access phytoplankton diversity in these environments.

Novel photosensitizing nanoparticles for PDT and biosensing applications

Loading of photosensitizing dyes into polymer beads is a meaningful strategy to improve their performance in photodynamic therapies (PDTs) or in sensing applications. In this work we describe a straightforward method for doping 390 nm and 26 nm carboxylated polystyrene nanoparticles with the hydrophobic tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) (RD3) complex. This Ru(II) photosensitizer (PS) efficiently generates singlet molecular oxygen (1O2) upon illumination with blue-green light and displays residual μs-lived red luminescence. its entrapment in the nanoparticles facilitates its use in water and opens up the possibility for bioconjugation without functionalization of the PS dye. After optimization of the doping protocol, we have carried out a photophysical (absorption, steady-state and time-resolved luminescence) and photochemical characterization of the photoactive nanoparticles by investigating the effect of the O2 concentration in water on the RD3 emission features. No leaching of the dye from the nanoparticles was observed. The 1O2 production quantum yield of the encapsulated PS (ΦΔ = 0.50), measured by monitoring the 1O2 emission decay at 1270 nm in D2O, is comparable to that of the free Ru(II) dye in the same solvent (0.49).

The Effects of Bilirubin and Lumirubin on the Differentiation of Human Pluripotent Cell-Derived Neural Stem Cells.

The ‘gold standard’ treatment of severe neonatal jaundice is phototherapy with blue–green light, which produces more polar photo-oxidation products that are easily excreted via the bile or urine. The aim of this study was to compare the effects of bilirubin (BR) and its major photo-oxidation product lumirubin (LR) on the proliferation, differentiation, morphology, and specific gene and protein expressions of self-renewing human pluripotent stem cell-derived neural stem cells (NSC). Neither BR nor LR in biologically relevant concentrations (12.5 and 25 µmol/L) affected cell proliferation or the cell cycle phases of NSC. Although none of these pigments affected terminal differentiation to neurons and astrocytes, when compared to LR, BR exerted a dose-dependent cytotoxicity on self-renewing NSC. In contrast, LR had a substantial effect on the morphology of the NSC, inducing them to form highly polar rosette-like structures associated with the redistribution of specific cellular proteins (β-catenin/N-cadherin) responsible for membrane polarity. This observation was accompanied by lower expressions of NSC-specific proteins (such as SOX1, NR2F2, or PAX6) together with the upregulation of phospho-ERK. Collectively, the data indicated that both BR and LR affect early human neurodevelopment in vitro, which may have clinical relevance in phototherapy-treated hyperbilirubinemic neonates.

Ultra-wideband phosphor Mg2Gd8(SiO4)6O2:Ce3+,Mn2+: Energy transfer and pressure-driven color tuning for potential applications in LEDs and pressure sensors

Energy transfer and pressure-driven color tuning phosphor Mg2Gd8(SiO4)6O2:Ce3+ (MGS:Ce3+), with ultra-wideband spectra was synthesized by high-temperature solid-state method. When the phosphor was excited by ultraviolet light, it emitted a sort of cold near-white light. The photoluminescence emission (PL) and excitation (PLE) spectra, luminescence sites of MGS:Ce3+ had been researched. In order to adjust the light color to achieve the purpose of spectral tuning, two methods had been implemented. The first method was doping Mn2+ into MGS:Ce3+. There was energy transfer from Ce3+ to Mn2+ in such phosphor, and the energy transfer had been researched in detail. After doping with Mn2+, the color coordinates positions and correlated color temperature (CCT) of phosphors were improved obviously. When fixed the concentration of Ce3+ and the doping concentration of Mn2+ is y = 1.0, 2.0 and 3.0, the phosphor can realize the warm white light emission. The second one was applying pressure to MGS:Ce3+, expecting to achieve the above purpose through the red shift of the spectrum. The results showed that the sample could withstand the high pressure of 26.03 GPa. A relatively rare phenomenon of pressure enhancement emission appeared when the pressure was between atmospheric pressure and 3.17 GPa. When the pressure exceeded 3.17 GPa, the luminescence intensity decreased regularly with the increase of pressure and the phosphor showed high pressure sensitivity (dλ / dP ≈ 1.8453 nm GPa−1). What’s more, the sample at compression environment made a significant red-shift about 60 nm of the emission bands. In the process of compression, the color coordinate shows that the light color of phosphor can be adjusted from blue-green light to yellow light region under the excitation of 355 nm. All above results revealed that the convenient synthetic method, effective light color coordinating made the MGS:Ce3+ and MGS:Ce3+,Mn2+ become a potential phosphor for (warm) white light. What’s more, the emission spectra red shift resulting from pressure change made it possible to be a potential optical pressure sensor.

The structure and luminescence properties of blue–green-emitting Sr2YNbO6: Bi3+ phosphors

The development of phosphor-converted white light-emitting diodes (w-LEDs) is in the ascendant. However, it is a constant pursuit to find the most suitable visible light emitting phosphors. Trivalent Bi ion is a kind of activator ion with a wide range of luminescence (from ultraviolet to visible). It has important application value for the study of luminescent properties of Bi3+ activated phosphors. The luminescent properties of blue-green-emitting Sr2YNbO6: xBi3+ phosphors were studied in this work. The phosphors can emit blue to blue-green light under near ultraviolet excitation from 329 to 374 nm. It is particularly important that the luminescence color can be adjusted by using different excitation wavelengths. This greatly enhances the flexibility of materials in lighting and display applications. The luminescence intensity (λex = 329 nm) at 498 K can still maintain 61.28% of that at 298 K. It indicates that the phosphors also have suitable luminescent thermal stability. All the results show that Bi3+ doped Sr2YNbO6 is a kind of luminescent material with potential application value in the field of w-LEDs.

A tetraphenylethylene derivative with reversible luminous colours applied in data security

Exploration of the relationship between molecular structure and properties of materials, particularly the multi-stimuli-responsive types, remain a challenge. Herein, we designed, synthesized and tested the photo-physical properties of a multi-stimuli-responsive TPE derivative (TPE-(C3Br)4). The TPE-(C3Br)4 exhibits piezochromic emitting deep-blue to green-blue light under external grinding. Interestingly, both non-ground and ground TPE-(C3Br)4 exhibits vapochromic and thermochromic properties. When exposed to CH2Cl2 vapor for 3 min and thereafter heated at 90 °C for 5 min or heat at 140 °C for 3 min and exposed to CH2Cl2 vapor for 2 s, TPE-(C3Br)4 reversibly glows between deep-blue and green-blue. The ground sample glows between green-blue and deep-blue under only one stimulus for a few min (e.g. heating or fuming alone). The multi-stimuli-responsive properties of TPE-(C3Br)4 are attributed to variation in intermolecular stacking and intramolecular twisting. The TPE-(C3Br)4 was used to develop a new encryption-decryption method. These findings demonstrate the utility of smart responsive TPE-(C3Br)4 material in developing data protection systems.