Red Radiation Research Articles

Bright white upconversion luminescence in rare-earth-ion-doped Y2O3 nanocrystals

Room temperature bright white upconversion (UC) luminescence in Yb3+–Tm3+–Er3+ ions doped Y2O3 nanocrystals was obtained under single-wavelength diode laser excitation of 976nm. The white light consists of the blue, green, and red UC radiations which correspond to the transitions G41→H63 of Tm3+, H11∕22∕S3∕24→I15∕24, and F9∕24→I15∕24 of Er3+ ions, respectively. The UC mechanisms were proposed based on spectral, kinetic, and pump power dependence analyses. The calculated color coordinates display that white light can be achieved in a wide range of pumping powers, which promises their potential applications in the field of displays, lasers, photonics, and biomedicine.

Radiação, fotossíntese, rendimento e qualidade de frutos em macieiras 'Royal Gala' cobertas com telas antigranizo

O objetivo deste trabalho foi avaliar a intensidade e a qualidade da radiação solar disponibilizada às plantas e os seus impactos sobre a fotossíntese, rendimento e qualidade dos frutos, em macieiras 'Royal Gala', cobertas ou não com telas antigranizo nas cores branca e preta. A tela preta provocou redução maior na densidade de fluxo de fótons fotossinteticamente ativos acima do dossel das plantas (24,8%), em comparação à tela branca (21,2%). O interior do dossel das plantas sob tela preta recebeu menores valores de radiação ultravioleta, azul, verde, vermelho e vermelho distante, bem como da relação vermelho:vermelho distante, em relação às plantas descobertas. Estas alterações na quantidade e qualidade da luz sob tela preta aumentaram o teor de clorofila total e a área específica nas folhas, e reduziram a taxa fotossintética potencial, o peso de frutos por cm² de seção transversal de tronco e a coloração vermelha dos frutos. As telas antigranizo branca e preta reduziram a incidência de queimadura de sol, porém não tiveram efeito sobre a severidade de "russeting" e sobre o número de sementes por fruto.

Effect of colored shade nets on pepper powdery mildew (Leveillula taurica)

The effect of colored shade nets with different shade intensities and qualities of irradiation transmittance on pepper powdery mildew was tested in mini-plots and field experiments. Leaf coverage byLeveillula taurica and leaf shedding due to the disease were more severe in the shade, by up to 275% and 70%, respectively, than in the open field. Leaf coverage byL. taurica symptoms and leaf shedding from plants grown under 25% shade black nets were higher, by up to 70% and 180%, respectively, than under 40% shade nets. The color of the shade nets affected the intensity of photosynthetically active (PAR), ultra-violet (UV), blue, red and far red radiations, the UV/blue light ratio, and percent PAR and UV transmitted. The various nets suppressed the disease differently. Black, blue-silver, green and red nets were associated with lower levels of disease in the field experiments. The red net was also superior in the mini-plots. The other results from the mini-plots were not similar to those from the field, probably reflecting more intensive epidemic development in the mini-plots. No interaction between net type and cultivar was found when two cultivars were grown under the nets. Yield was higher under nets than in the open; nevertheless, the yield from plants grown under the 40% shade black net was not higher than that of the plants under the 25% black net, despite the significantly lower levels of disease at the higher shade intensity. B-quality pepper yield was significantly higher in the plots covered by 25% shade. Yield differences between the different colored nets were also not well correlated with disease levels, probably due to factors negating the direct effect of the nets on the plants and their yield. Implementation of either ‘friendly’ (Ampelomyces quisqualis AQ10/Trichoderma harzianum T39/ sulfur/ neem seed extract) or chemical (sulfur/ pyrifenox/ Polyoxin AL/ myclobutanil/ azoxystrobin) spray regimes successfully reduced disease severity under the different nets. There was no interaction between net type and spray regime. Thus, growing sweet pepper under shade nets results in increased yields and also in higher powdery mildew severity. Disease is negatively associated with the rate of shading and is variably affected by the quality of light filtered through the different colored shade nets.

Upconversion mechanism for two-color emission in rare-earth-ion-dopedZrO2nanocrystals

Two-color upconversion (UC) emissions with anomalous power dependence were observed in spectrally tailored rare-earth-ion-doped $\mathrm{Zr}{\mathrm{O}}_{2}$ nanocrystals. Single green and red UC radiation in the visible range was induced by $980\phantom{\rule{0.3em}{0ex}}\mathrm{nm}$ diode laser excitation in $\mathrm{Zr}{\mathrm{O}}_{2}:{\mathrm{Er}}^{3+}$ and $\mathrm{Zr}{\mathrm{O}}_{2}:{\mathrm{Er}}^{3+}+{\mathrm{Yb}}^{3+}$ nanocrystals, yielding quadratic and linear laser power dependences, respectively. The UC spectrum design is enabled by the saturation of the $^{4}I_{13∕2}(\mathrm{Er})$ state through the efficient energy back-transfer process $^{4}S_{3∕2}(\mathrm{Er})+^{2}F_{7∕2}(\mathrm{Yb})\ensuremath{\rightarrow}^{4}I_{13∕2}(\mathrm{Er})+^{2}F_{5∕2}(\mathrm{Yb})$ induced by high ${\mathrm{Yb}}^{3+}$-ion concentration. The anomalous power dependence originates from the fact that the UC rate of the $^{4}I_{11∕2}(\mathrm{Er})$ state at high ${\mathrm{Yb}}^{3+}$-ion concentrations is fundamentally much larger than its decay rate. These conclusions obtained are confirmed by theoretical investigations based on steady-state rate equations.

Spectral composition of photosynthetically active radiation penetrating into a Norway spruce canopy: the opposite dynamics of the blue/red spectral ratio during clear and overcast days

The spectral composition of photosynthetically active radiation (PAR) during clear and overcast days was studied above the canopy (U) and at two layers of a dense Norway spruce stand [Picea abies (L.) Karst.] characterized with an average LAI = 7.3 ± 0.8 (middle layer: M) and 12.3 ± 0.7 (lower layer: L). Whereas the spectral composition of PAR incoming on the canopy surface during cloudy days (characterized by diffuse index DI > 0.7) was almost independent of the solar elevation angle, the proportion of the blue-green spectral region of PAR was significantly reduced at low elevation angles during days with prevailing direct radiation (DI < 0.3). The PAR spectrum at both M and L levels was only slightly enriched in the green spectral region (more pronounced for DI < 0.3). The penetration of diffuse radiation into the canopy resulted in a slight (approx. 5%) reduction of the blue region proportion that remained stable during the day. On the contrary, under clear sky conditions the penetration of blue and red radiation was dependent on the solar elevation in an opposite manner in comparison with the spectral composition of PAR incident on canopy, giving almost twofold proportion of the blue part of the spectrum at a low elevation angle at M layer. We suggest that the blue enhancement of the spectrum within the Norway spruce canopy during clear days is due to a specific spatial arrangement of the assimilatory apparatus of a coniferous stand. Further, the possible consequences of the observed dynamics of the PAR spectrum inside the canopy during clear days on the efficiency of PAR absorption of the needles located within the canopy are discussed.

Frequency-selective self-trapping and supercontinuum generation in arrays of coupled nonlinear waveguides

We study spatiotemporal dynamics of soliton-induced twooctave- broad supercontinuum generated by fs pulses in an array of coupled nonlinear waveguides. We show that after fission of the input pulse into several fundamental solitons, red and blue-shifted nonsolitonic radiation, as well as solitons with lower intensity, spread away in transverse direction, while the most intense spikes self-trap into spatiotemporal discrete solitons.

Power scaling of semiconductor laser pumped Praseodymium-lasers

We report on efficient lasing of Pr-doped fluoride materials with cw output powers up to 600 mW in the visible spectral range. Praseodymium doped LiYF(4) and LiLuF(4) crystals were pumped either by an intracavity frequency doubled optically pumped semiconductor laser with output powers up to 1.6 W and nearly diffraction limited beam quality or by a multimode GaN-laser diode with an output power of about 370 mW. Furthermore, intracavity frequency doubling of the red Pr-laser radiation to 320 nm reaching output powers of more than 360 mW with a conversion efficiency of 61% and an optical-to-optical efficiency of 22% are presented.

The role of low intensity red luminescent radiation in the control of Arabidopsis thaliana morphogenesis and hormonal balance

The effects of low intensity red luminescent radiation emitted by the polyethylene light-correcting film due to the conversion of UV-A radiation on Arabidopsis thaliana (L.) Heynh. morphogenesis and hormonal balance were studied. Wild-type Ler plants and two mutants, hy3 and hy4, displaying disturbances in the synthesis of phytochrome B and cryptochrome 1, respectively, were compared. In wild-type and hy4 plants grown under the light-correcting film, growth and development were substantially accelerated, whereas, in hy3 plants, they were retarded. These changes were correlated with changes in the levels of endogenous hormones, both growth activators and inhibitors. We concluded that low intensity red luminescent radiation affected the plant hormonal balance. In its turn, the changes in the hormone ratios, growth stimulators and inhibitors, affected the rate of plant growth and their productivity.

Ultrastructural and autoradiographical analysis show a faster skin repair in He–Ne laser-treated wounds

There are evidences that low-intensity red laser radiation is capable to accelerate wound healing. Nowadays, this therapy has been gradually introduced in clinical practice although mechanisms underlying laser effects are poorly understood. To better understand the photobiological effects of laser radiation, this study investigated by electron microscopy, immunohistochemistry and autoradiography the morphological and functional features of irradiated and none irradiated injured mice skin. Full-thickness skin lesions were created on the back of mice and irradiated on days 1, 5, 8, 12, and 15 post-wounding with a He–Ne laser ( λ = 632.8 nm), dose 1 J/cm 2, exposure time 3 min. Non-irradiated lesions were used as a control. The mice were inoculated with 3H-proline and sacrificed one hour after on the 8th, 15th and 22nd days to histological and radioautographical analysis. The irradiated-lesions showed a faster reepithelization compared with control lesions. The irradiated dermis contained a higher number of activated fibroblasts compared to control group and, most of them showed several cytoplasmic collagen-containing phagosomes. In irradiated-lesions, smooth muscle α-actin positive cells predominated, which correspond to a higher number of myofibroblasts observed in the electron microscope. Moreover, laser radiation reduced the local inflammation and appears to influence the organization of collagen fibrils in the repairing areas. Quantitative autoradiography showed that the incorporation of 3H-proline was significantly higher in irradiated-dermis on the 15th day post-wounding ( p < 0.05). These results suggest that laser radiation may accelerate cutaneous wound healing in a murine model.

Melatonin in Glycyrrhiza uralensis: response of plant roots to spectral quality of light and UV‐B radiation

Melatonin (N-acetyl-5-methoxytryptamine) is known to be synthesized and secreted by the pineal gland in vertebrates. Evidence for the occurrence of melatonin in the roots of Glycyrrhiza uralensis plants and the response of this plant to the spectral quality of light including red, blue and white light (control) and UV-B radiation (280-315 nm) for the synthesis of melatonin were investigated. Melatonin was extracted and quantified in seed, root, leaf and stem tissues and results revealed that the root tissues contained the highest concentration of melatonin; melatonin concentrations also increased with plant development. After 3 months of growth under red, blue and white fluorescent lamps, the melatonin concentrations were highest in red light exposed plants and varied depending on the wavelength of light spectrum in the following order red >> blue > or = white light. Interestingly, in a more mature plant (6 months) melatonin concentration was increased considerably; the increments in concentration were X4, X5 and X3 in 6-month-old red, blue and white light exposed (control) plants, respectively. The difference in melatonin concentrations between blue and white light exposed (control) plants was not significant. The concentration of melatonin quantified in the root tissues was highest in the plants exposed to high intensity UV-B radiation for 3 days followed by low intensity UV-B radiation for 15 days. The reduction of melatonin under longer periods of UV-B exposure indicates that melatonin synthesis may be related to the integrated (intensity and duration) value of UV-B irradiation. Melatonin in G. uralensis plant is presumably for protection against oxidative damage caused as a response to UV irradiation.

131I-Metaiodobenzylguanidine (131I-MIBG) double infusion with autologous stem cell transplant for neuroblastoma: A New Approaches to Neuroblastoma Therapy (NANT) study

9011 Background: 131I-MIBG provides targeted radiotherapy with &gt;30% response in refractory neuroblastoma, but the activity infused is limited by radiation safety and hematologic toxicity. The goal was to determine the maximum tolerated dose of 131I-MIBG in two consecutive infusions at a 2-week interval, supported by autologous stem cell transplant (ASCT) 2 weeks after the second dose. Methods: The 131I-MIBG was escalated in a 3+3 Phase I trial design, with levels calculated by total red marrow radiation index (RMI) from the double infusion. The first infusion of 131I-MIBG was 12, 15, 18 and 21 mCi/kg for levels 1, 2, 3 and 4 respectively. Using detailed dosimetry, the second infusion was adjusted to achieve the target RMI, except at Level 4, where the second infusion was capped at 21 mCi/kg. Results: Twenty-one patients were enrolled at Level 1–4, with 18 evaluable for toxicity. Median age at enrollment was 7 years, all were heavily pretreated, including 12 with prior high dose therapy and ASCT, and 12 patients had bone marrow tumor. Cumulative 131I-MIBG given to achieve the target RMI ranged from 18 mci/kg to 49 mCi/kg. RMI delivered per mCi of MIBG decreased in 15/19 patients by mean of 0.21 cGy/mCi with the second infusion. Hematologic toxicity was acceptable, with median time to ANC&gt;500 after ASCT of 13 (4–27) days. Platelet transfusion was required in 15/18 patients, with median time to platelet independence of 18 (6–47) days after ASCT. There were no non-hematologic toxicities above grade 2 attributed to therapy, though 9 patients had grade 1–2 elevations of transaminase, and 1 had grade 2 hypothyroidism. Responses in 17 evaluable patients included 1 PR, 4 MR, 6 SD, and 6 PD. Eleven patients are alive at median of 361 days (46–483); 5 died of PD and 1 of unrelated toxicity. Conclusion: The lack of toxicity with this approach allowed dramatic dose intensification of 131I-MIBG, with minimal toxicity and the possibility of improved response. [Table: see text] No significant financial relationships to disclose.

Effect of monochromatic light of low intensity on L929 skin fibroblast culture

Effects of exposure to low-intensity monochromatic red spectrum radiation in different modes were studied on L929 skin fibroblast culture. Radiometric and cytological study of cell culture before and after irradiation showed that monochromatic low-intensity radiation stimulated skin fibroblasts in L929 culture under certain conditions.

Single-frequency quasi-continuous red radiation generated by a green-pumped singly resonant optical parametric oscillator

We demonstrate the operation of a quasi-continuous-wave optical parametric oscillator (OPO) in the red part of the visible spectrum by direct pumping from a frequency-doubled quasi-continuous-wave Nd:YAG laser. The OPO is singly resonant and based on a MgO-doped periodically poled stoichiometric lithium tantalate crystal. A single-frequency 1.2 W output power is obtained when an etalon is inserted inside the cavity.

Photosensitization of different Candida species by low power laser light

The aim of this study was to evaluate the effects of the laser radiation (685 nm) associated with photosensitizers on viability of different species of Candida genus. Suspensions of Candida albicans, Candida dubliniensis, Candida krusei and Candida tropicalis, containing 10 6 viable cells per milliliter were obtained with the aid of a Neubauer’s chamber. From each species, 10 samples of the cell suspension were irradiated with diode laser (685 nm) with 28 J/cm 2 in the presence of methylene blue (0.1 mg/ml), 10 samples were only treated with methylene blue, 10 samples were irradiated with laser in the absence of the dye, 10 samples were treated with the dye and irradiated with laser light and 10 samples were exposed to neither the laser light nor to the methylene blue dye. From each sample, serial dilutions of 10 −2 and 10 −3 were obtained and aliquots of 0.1 ml of each dilution were plated in duplicate on Sabouraud dextrose agar. After incubation at 37 °C for 48 h, the number of colony-forming units (CFU/ml) was obtained and data were submitted to ANOVA and Tukey’s test ( p < 0.05). Laser radiation in the presence of methylene blue reduced the number of CFU/ml in 88.6% for C. albicans, 84.8% for C. dubliniensis, 91.6% for C. krusei and 82.3% for C. tropicalis. Despite of this, only laser radiation or methylene blue did not reduce significantly the number of CFU/ml of Candida samples, except for C. tropicalis. It could be concluded that the photo activation of methylene blue by the red laser radiation at 685 nm presented fungicide effect on all Candida species studied.

Development of Practical Plant Factory with Artificial Supplemental Lighting System for the Growth of Vegetable Seedlings

For stable mass production of vegetable seedlings with good quality, a commercial greenhouse nursery needs a supplemental lighting system that is not affected by light fluctuations under natural solar conditions. Therefore, a practical plant nursery covering a 12 × 24 m area, and using a supplemental lighting system, was developed for the growth of vegetable seedlings. The developed lighting system had 400-W mercury-free, high pressure sodium lamps with reflectors, which produced a red radiation to far-red radiation photon flux (R/FR PF) ratio of 1.1. This is similar to that of solar radiation. And over about 60 μmol m-2 s-1 of PPFD was realized for stable and healthy growth of vegetable seedlings. By using a simulation model of horizontal distribution of PPFD on two cultivation beds (each bed area: 4.6 × 22.6 m) under 100 lamps, it was found that the system had high uniformity of lighting on the two beds. Observed value of illuminance and PPFD and uniformity also satisfied the planned specifications. By repeating a seedling growth experiment using various plants in this greenhouse, it is expected that the practical and effective use of this supplemental lighting system will be possible in rainy seasons or in the late winter period.

Monitoring leaf photosynthesis with canopy spectral reflectance in rice

Non-destructive and rapid method for assessment of leaf photosynthetic characteristics is needed to support photosynthesis modelling and growth monitoring in crop plants. We determined the quantitative relationships between leaf photosynthetic characteristics and canopy spectral reflectance under different water supply and nitrogen application rates. The responses of reflectance at red radiation (wavelength 680 nm) to different water contents and nitrogen rates were parallel to those of leaf net photosynthetic rate (PN). The relationships of reflectance at 680 nm and ratio index of R(810,680) (near infrared/red, NIR/R) to PN of different leaf positions and leaf layers in rice indicated that the top two full leaves were the best leaf positions for quantitative monitoring of leaf PN with remote sensing technique, and the ratio index R(810,680) was the best ratio index for evaluating leaf photosynthetic characteristics in rice. Testing of the models with independent data sets indicated that R(810,680) could well estimate PN of top two leaves and canopy leaf photosynthetic potential in rice, with the root mean square error of 0.25, 0.16, and 4.38, respectively. Hence R(810,680) can be used to monitor leaf photosynthetic characteristics at different growth stages of rice under diverse growing conditions.

Spectral quality and UV-B stress stimulate glycyrrhizin concentration of Glycyrrhiza uralensis in hydroponic and pot system

Glycyrrhizin, the major bioactive component of Glycyrrhiza uralensis, is widely used as a natural sweetener. Recently glycyrrhizin has been shown to have anti-tumor activity, highly active in inhibiting replication of HIV-1 and SARS-associated virus and exhibits a number of pharmacological effects. The principle objective of the current study was to evaluate the effects of different spectral quality including red, blue, white and UV-B radiation on the production of glycyrrhizin, in a controlled environment. Plants were grown under artificial lights with elevated CO 2 concentration and both the pot and hydroponic plants were assigned to red and blue light treatments and those grown under white fluorescent lamps were used as control. In a separate experiment, pot plants were exposed to ultraviolet (UV)-B radiation (wavelength: 280–315 nm). The net photosynthetic rates (NPR) of the leaves reduced significantly immediately after exposure to the high intensity UV-B radiation (3 days at 1.13 W m −2). In case of the low intensity UV-B radiation (15 days at 0.43 W m −2), NPR was also reduced, but the rate of reduction was significantly slower than that of the high intensity treatment. The concentrations of glycyrrhizin quantified in the root tissues were highest in the plants grown under red light in both hydroponic and pot systems and the concentration increased linearly from 1- to 3-month-old pot plants. Both the low and high intensity of UV-B exposure increased the concentration of glycyrrhizin in the root tissues of 3-month-old pot plants, the values being nearly X1.5 those of the control. The results also indicate that the glycyrrhizin concentrations of 3–6 months old pot plants were similar or even higher than the previously reported values for 3–4 years old field-grown plants and confirm that high concentration of glycyrrhizin production is possible within a very short production period under controlled environments.

Effects of Short-term Red Radiation and Choline Compounds on Cytokinin Content, Chlorophyll Accumulation and Photomorphogenesis in Wheat Seedlings

Effects of choline compounds (2-chloroethyltrimethylammonium chloride and 2-ethyltrimethylammonium chloride) as well as red radiation (R) pulse on the dynamics of cytokinin changes, growth and chlorophyll (a + b) accumulation were studied during the growth and greening of etiolated wheat seedlings (Triticum aestivum L., var. Mironovskaya-808). The seedlings were grown for 120 h in the dark and then exposed for 72 h to white light. Pre-treatment of caryopses with cholines and pre-irradiation of etiolated seedlings with R inhibited elongation of both coleoptile and first leaf; but the same factors accelerated these growth responses when seedlings were exposed to white light. Chlorophyll (Chl) accumulation and the first leaf appearance from coleoptile were accelerated by the pre-treatments as well. Far-red radiation (FR) reversed all effects of R but choline pre-treatment eliminated partly R/FR photoreversibility. Two compounds with high cytokinin activity (tested on a fresh weight basis by the bioassay with Amaranthus caudatus L.) were found in shoots and first leaves. One of them had Rf, UV absorbance spectrum and the biological activity similar to N6-(Δ2-isopentenyl)adenosine. Another cytokinin-like substance was not identified with the used standards. Stimulation of greening by R pulse and cholines was accompanied with accelerated accumulation of both cytokinin-like substances. We conclude that the influence of R and cholines on the concentration of substances with cytokinin activities detected in the leaves might be involved in the stimulation of Chl accumulation.

Photoregulated or Energy Dependent Process of Hormogonia Differentiation inNostoc sphaeroidesKützing (Cyanobacterium)

Abstract: Hormogonium, which was thought to play an important role in the dispersal and survival of these microorganisms in their natural habitats, is a distinguishable developmental stage of heterocystous cyanobacteria. The present study examined the effects of different light conditions and sugars on the differentiation of Nostoc sphaeroides Kützing to the hormogonia stage. Results showed that differentiation of hormogonia was light dependent in the absence of sugar, but that close to 100% of cyanobacteria differentiated to hormogonia in the presence of glucose or sucrose, irrespective of the light conditions. This differentiation was inhibited, even in the presence of sugars, upon application of an inhibitor of respiration. Following the testing of different sugars, the effects of different lights were examined. It was found that 5–10 umol-nT2-s-1 photon flux density was optimal for hormogonia differentiation. One hundred percent differentiation was obtained with white light irradiation, in contrast with irradiation with green light (80% differentiation) and red light (0–10% differentiation). Although they showed different efficiencies in inducing hormogonia differentiation in N. sphaeroides, the green and red radiation did not display antagonistic effects. When the additional aspect of time dependence was investigated through the application of different light radiations and an inhibitor of protein synthesis, it was found that the initial 6 h of the differentiation process was crucial for hormogonia differentiation. Taken together, these results show that hormogonia differentiation in N. sphaeroides is either a photoregulated or an energy dependent process. (Managing editor: Ping HE)

Multi-Color Coherent Radiation in a Two-Dimensional Nonlinear Photonic Crystal with Rectangular Lattices

The two-dimensional nonlinear photonic crystal: a periodically poled lithium niobate with rectangular lattice, was fabricated using field poling technique in this work. Red, yellow, green, blue, and violet coherent radiations were generated in the crystal by frequency doubling and tripling the output of a tunable optical parametric oscillator in the collinearly and non-collinearly quasi-phase-matching geometries. The results show that two-dimensional nonlinear crystal could be used to generate various colors simultaneously if the crystal was illuminated by the z-polarized fundamental beams of different wavelengths along different directions. Therefore, its application in the field of color display and integrated optics may be expected.