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SUMMARY Objectives This study evaluated the effect of using three commercial light curing units (LCUs) delivering a range of irradiance values, but delivering similar radiant exposures on the depth of cure of two different resin-based composites (RBCs). Methods A conventional hybrid RBC (Z100 shade A2, 3M ESPE) or a bulk fill RBC (Tetric EvoCeram Bulk Fill shade IVA, Ivoclar Vivadent) was packed into a 10-mm deep semicircular metal mold with a 2-mm internal radius. The RBC was exposed to light from a plasma-arc-curing (PAC) light (Sapphire Plus, DenMat) for five seconds, a quartz-tungsten-halogen (QTH) light (Optilux 501, Kerr) for 40 seconds, or a light-emitting-diode (LED) light (S10, 3M ESPE) for 20 seconds and 40 seconds (control). The Knoop microhardness was then measured as soon as possible at the top surface and at three points every 0.5 mm down from the surface. For each RBC, a repeated measures analysis of variance (ANOVA) model was used to predict the Knoop hardness in a manner analogous to a standard regression model. This predicted value was used to determine at what depth the RBC reached 80% of the mean hardness achieved at the top surface with any light. Results The PAC light delivered an irradiance and radiant exposure of 7328 mW/cm2 and 36.6 J/cm2, respectively, to the RBCs; the QTH light delivered 936 mW/cm2 and 37.4 J/cm2 and in 20 seconds the LED light delivered 1825 mW/cm2 and 36.5 J/cm2. In 40 seconds, the control LED light delivered a radiant exposure of 73.0 J/cm2. For Z100, using 80% of the maximum hardness at the top surface as the criteria for adequate curing, all light exposure conditions achieved the 2.0-mm depth of cure claimed by the manufacturer. The LED light used for 40 seconds achieved the greatest depth of cure (5.0 mm), and the PAC light used for five seconds, the least (2.5 mm). Tetric EvoCeram Bulk Fill achieved a 3.5-mm depth of cure when the broad-spectrum QTH light was used for 40 seconds delivering 37.4 J/cm2. It required a 40-second exposure time with the narrow-spectrum LED, delivering approximately 73 J/cm2 to reach a depth of cure of 4 mm. Conclusions When delivering a similar radiant exposure of 37 J/cm2, the QTH (40 seconds) and LED (20 seconds) units achieved a greater depth of cure than the PAC (five seconds) light. For both resins, the greatest depth of cure was achieved when the LED light was used for 40 seconds delivering 73 J/cm2 (p

Solar Home Systems (SHS) have recently gained prominence as the most promising solution for increasing energy access in remote, off-grid communities. However, the higher than standard testing conditions (STC) temperatures have a significant impact on the SHS components like PhotoVoltaic (PV) module and battery. A modeling methodology is described in this study for quantifying the temperature impact on SHS. For a particular location with high irradiation and temperatures and a given load profile, an SHS model was simulated, and the temperature-impact was analyzed on the performance and lifetime of the SHS components. Different PV module temperature estimation models were applied, and the corresponding dynamic PV outputs were compared. The nominal operating cell temperature (NOCT) model was found inadequate for estimating PV module temperatures under high irradiance conditions. The PV yield was found to be affected by almost 10% due to thermally induced losses. When different levels of temperature variations were considered, the battery lifetime was seen to be up to 33% less than that at 25 ° C. The modeling methodology presented in this paper can be used to include the thermal losses in SHS for rural electrification, which can further help accordingly in system sizing.

A research station for photovoltaics purposes was installed under outdoor high irradiance conditions during 8 months at the Atacama Desert: a meteorological station, two IV tracers connected to two PV modules in order to study the soiling phenomena and four IV tracers connected to monocrystalline, polycrystalline, thin film and bifacial modules. Performance ratio of bifacial technology assuming only the nominal power of the front face reaches 96%, thin film reaches 90%, polycrystalline reaches 88% and monocrystalline reaches 78%. The soiling ratio decreases less than 2.5% during first two months and after it was found a natural cleaning effect due to high humidity that occurs often at early morning and keep the soiling ratio at 0.94 ± 0.01. Further work will be focus on the concept of dew point in order to understand the natural cleaning effects.

Photosynthetic adaptation may be defined as environmentally induced adjustments in physiology, anatomy, and morphology that enable a plant to photosynthesize more efficiently in a new environment. Adaptation to high irradiance often results in higher light-saturation ranges for photosynthesis and greater photosynthetic rates per unit leaf area at light saturation. Adaptation to low irradiance, on the other hand, may result in lower light-saturation ranges, lower light-compensation points, lower maximum photosynthetic rates, and lower dark-respiration rates. This chapter deals with photosynthetic adaptation to both light and temperature. It considers a number of examples of photosynthetic light adaptation and examine some of the mechanisms accounting for it. The chapter shows how changes in leaf characteristics at the organ, cellular, and subcellular level contribute to the observed effects of irradiance on gas exchange characteristics. It points out various leaf characteristics that are modified in response to irradiance during growth.

Taking service-life prediction to the next level demands a better understanding of how the effects of accelerated weathering compare with results obtained under natural weathering conditions. Useful service-life estimates require that degradation pathways stemming from the two methods be the same. Potential deviation from this requirement is particularly an issue when accelerated testing is conducted at high levels of stress. Using vinyl and poly(ethylene terephthalate) films as model materials, the impact of irradiance, temperature, and humidity on degradation has been evaluated in a series of accelerated laboratory exposures. Results reveal multiple failure modes, each of which displays a unique dependence on the applied stresses. Comparison to degradation observed from natural outdoor exposures enables assessment of the limitations, determination of the constraints, and interpretation of the data relating to accelerated weathering, all of which must be considered for service-life prediction.

We present an economical and scalable method to fabricate concentrators using 3D-printed molds and PDMS. The integrated system can deliver Jsc up to 20 times and powers up to 13 times that of a bare solar cell. We have also observed significant increases in Voc, and use our devices to elucidate complicated carrier dynamics and limiting factors in CQD solar cells under high irradiance.

Light and temperature are major drivers in the ecology and biogeography of symbiotic dinoflagellates living in corals and other cnidarians. We examined variations in physiology among 11 strains comprising five species of clade A Symbiodinium . We grew cultures at 26°C (control) and 32°C (high temperature) over a duration of 18 days while measuring growth and photochemical efficiency ( F v / F m ). Responses to thermal stress ranged from susceptible to tolerant across species and strains. Most strains exhibited a decrease in cell densities and F v / F m when grown at 32°C. Tolerance to high temperature ( T 32 ) was calculated for all strains, ranging from 0 (unable to survive at high temperature) to 1 (able survive at high temperature). There was substantial variation in thermotolerance across species and among strains. One strain had a T 32 close to 1, indicating that growth was not reduced at 32°C for only this one strain. To evaluate the combined effect of temperature and light on physiological stress, we selected three strains with different levels of thermotolerance (tolerant, intermediate and susceptible) and grew them under five different light intensities (65, 80, 100, 240 and 443 µmol quanta m −2 s −1 ) at 26 and 32°C. High irradiance exacerbated the effect of high temperature, particularly in strains from thermally sensitive species. This work further supports the recognition that broad physiological differences exist not only among species within Symbiodinium clades, but also among strains within species demonstrating that thermotolerance varies widely between species and among strains within species.

The effects of irradiance and temperature on growth and flowering in seed propagated Sinningia cardinalis especially to increase the number of flowers were investigated. To understand the effect of irradiance on flowering and the number of flowers, seedlings were grown under 30% shade (30% SH), natural irradiance (ND), and ND supplemented with 14 h of high irradiance at 14 W/m2 (ND + 14HID) at 3 stages (ST) lasted for 40 days (d) at each ST (Expt. 1). Flowering was the earliest (205 d) when 20-d old plants were grown under 30% SH during the entire three stages (July 1 through October 31). Longer than 215 d to flower was required when plants received ND + 14HID during stage 3 (ST 3) (September 21–October 31). The number of flowers was highest (22) when grown under 30% SH during ST 1 (July 1–August 10) followed by ND or ND + 14HID during the ST 2 (August 12–September 20) or ST 3. To investigate the effect of temperature on flowering and the number of flowers, 42 d of 15/13 °C (15 °C), 19/17 °C (19 °C), 23/21 °C (23 °C), and 27/25 °C (27 °C) and under ND + 10HDI were given to 45-d old plants (Expt. 2). The number of days to flower was only significantly accelerated at 23° and 27 °C as compared to 15 °C and 19 °C, but not by irradiance treatments. The highest number of flowers (24) was produced when plants were grown at 15 °C under ND + 10HID given prior to formation of three pairs of leaves (

To evaluate ex vivo biomechanical and enzymatic digestion resistance differences between standard myopic laser in-situ keratomileusis (LASIK) compared with LASIK+CXL, in which high-irradiance cross-linking (CXL) is added.Eight human donor corneas were subjected to femtosecond-assisted myopic LASIK. Group A (n=4) served as a control group (no CXL). The corneas in LASIK+CXL group B were subjected to concurrent prophylactic high-irradiance CXL (n=4). Saline-diluted (0.10%) riboflavin was instilled on the stroma, subsequently irradiated with UV-A through the repositioned flap. The cornea stroma and flap specimens were separately subjected to transverse biaxial resistance measurements; biomechanical differences were assessed via stress and Young's shear modulus. Subsequently, the specimens were subjected to enzymatic degradation.For the corneal stroma specimen, stress at 10% strain was 128±11 kPa for control group A versus 293±20 kPa for the LASIK+CXL group B (relative difference Δ=+129%, p0.05). The stress in group B was also increased at 20% strain by +68% (p0.05). Shear modulus in group B was increased at 10% strain by +79%, and at 20% strain by +48% (both statistically significant, p0.05). The enzymatic degradation time to dissolution was 157.5±15.0 min in group A versus 186.25±7.5 min in group B (Δ=+18%, p=0.014). For the flaps, both biomechanical, as well as enzymatic degradation tests showed no significant differences.LASIK+CXL appears to provide significant increase in underlying corneal stromal rigidity, up to +130%. Additionally, there is significant relevant enzymatic digestion resistance confirmatory to the above. LASIK flaps appear unaffected biomechanically by the LASIK+CXL procedure, suggesting effective CXL just under the flap.

The use of Aspergillus niger (A. niger) fungal spores as challenge organism for UV reactor validation studies is attractive due to their high UV-resistance and non-pathogenic nature. However A. niger spores UV dose-response was dependent upon sporulation conditions and did not follow the Bunsen-Roscoe Principle of time-dose reciprocity. Exposure to 8 h of natural sunlight for 10 consecutive days increased UV resistance when compared to spores grown solely in dark conditions. Application of 250 mJ cm(-2) at high irradiance (0.11 mW cm(-2)) resulted in a 2-log inactivation; however, at low irradiance (0.022 mW cm(-2)) a 1-log inactivation was achieved. In addition, surface electron microscopy (SEM) images revealed morphological changes between the control and UV exposed spores in contrast to other well accepted UV calibrated test organisms, which show no morphological difference with UV exposure.

West sides of the coral Coelastrea aspera, which had achieved thermo-tolerance after previous experience of high solar irradiance in the field, were rotated through 180o on a reef flat in Phuket, Thailand (7o50´N, 98o25.5´E), in 2000 in a manipulation experiment and secured in this position. In 2010, elevated sea temperatures caused extreme bleaching in these corals, with former west sides of colonies (now facing east) retaining four times higher symbiont densities than the east sides of control colonies, which had not been rotated and which had been subject to a lower irradiance environment than west sides throughout their lifetime. The reduced bleaching susceptibility of the former west sides in 2010, compared to handling controls, suggests that the rotated corals had retained a ‘memory’ of their previous high irradiance history despite living under lower irradiance for 10 years. Such long-term retention of an environmental ‘memory’ raises important questions about the acclimatisation potential of reef corals in a changing climate and the mechanisms by which it is achieved.

Purpose To document the first presented report in December 2008 of high irradiance riboflavin/ultraviolet A (UVA) corneal cross-linking in comparison with that of standard irradiance and of fractionated exposure to increase the time for oxygen diffusion into the cornea. Methods After in vitro studies of oxygen depletion and cross-linking density using type 1 human collagen gels, 36 ex vivo porcine globes were deepithelialized and exposed to 0.1% riboflavin drops in carboxymethylcellulose solution every 5 min for 3 initial doses and then throughout irradiation afterward. Six eyes each were irradiated with 370-nm UVA light at 2, 3, 9, and 15 mW/cm continuously and 15 mW/cm fractionated (with alternate cycles of 30 s "ON" and 30 s "OFF" exposure) using an equivalent radiant exposure of 5.4 mJ/cm. The final six eyes received no UVA exposure as a control. The exposed corneas were then dissected and subjected to extensiometry. Analysis of variance with Bonferroni post hoc test was performed between groups. Results The stress required to induce a 10% strain for the control eyes (no UVA) was 100.6±20.9×10 N/m in comparison with the stress of 3 mW/cm (standard irradiation) at 146.7±17.6×10 N/m (P=0.009). The stress at the other equidose irradiances of 2, 9, 15 continuously, and 15 mW/cm fractionated were 140±21.9, 162.8±70, 154.1±70, and 163.0±64×10 N/m, respectively. When comparing the irradiances of 15 mW/cm continuously and fractionated to the standard irradiation, the stress was not statistically different (P=0.799 and 0.643), respectively. Conclusion High irradiance riboflavin/UVA cross-linking with equivalent energy exposure demonstrates comparable efficacy in stiffening corneal collagen with standard irradiance, but with considerably less exposure time. Over the past 6 years, since this report was first presented, the use of high irradiance cross-linking has been gaining popularity.

The present study aims to present the current status of the results obtained using Elkem Solar Silicon (ESS™) as feedstock basis for solar cell and modules. It is shown that solar cells based on ESS™ are able to follow the development of the solar industry obtaining comparable efficiencies to standard polysilicon based cells. The characteristics of ESS™ based solar cells, having normally higher V oc and FF and lower I sc , seem to give clear advantages in the field for solar modules located at high irradiance areas. Results from several locations show enhanced electricity production of ESS™ based solar modules compared to polysilicon at increasing solar irradiance. This is explained by beneficial temperature coefficients for ESS™ based solar cells. Lower electrical loss for ESS™ modules is also expected to contribute to the same beneficial performance under conditions of high solar irradiance.

Optogenetics is widely used in fundamental neuroscience. Its potential clinical translation for brain neuromodulation requires a careful assessment of the safety and efficacy of repeated, sustained optical stimulation of large volumes of brain tissues. This study was performed in rats and not in non-human primates for ethical reasons. We studied the spatial distribution of light, potential damage, and non-physiological effects in vivo, in anesthetized rat brains, on large brain volumes, following repeated high irradiance photo-stimulation. We generated 2D irradiance and temperature increase surface maps based on recordings taken during optical stimulation using irradiance and temporal parameters representative of common optogenetics experiments. Irradiances of 100 to 600 mW/mm2 with 5 ms pulses at 20, 40, and 60 Hz were applied during 90 s. In vivo electrophysiological recordings and post-mortem histological analyses showed that high power light stimulation had no obvious phototoxic effects and did not trigger non-physiological functional activation. This study demonstrates the ability to illuminate cortical layers to a depth of several millimeters using pulsed red light without detrimental thermal damages.

In this study, we have presented proton energy spectra produced by such high irradiance (1020 W/cm2 ) lasers interacting with a pre formed plasma in front of the target and with solid targets without a pre formed plasma. The effects of the target thickness and the generated plasma on the maximum energy and proton numbers are assessed. It is observed that experimentally measured maximum proton energy and number of protons have a dependence on target thickness and preformed plasma scale length produced by prepulse laser with the irradiance of ? 1012 W/cm2 . 2D EPOCH PIC code simulation results of the energy spectra of protons are in a good agreement with measured experimental results. Yapılan bu çalışmada,ultra yogun lazerlerin ( ? 1020 W/cm2 ) farklı kalınlıktaki katı hedeflerle etkileşimi sonucu üretilen protonlar incelenmiştir. Ayrıca ana lazerden önce kullanılan ve younluğu? 1012 W/cm2 seviyesinde olan ikincil lazerle önceden oluşturulmuş plazmaların, üretilen protonların enerji spektrumları üzerindeki etkisi araştırılmıştır. Ana lazer tarafından ateşlenen katı hedeflerin kalınlıgının, üretilen protonların yoğunluğu ve maksimum enerjilerine olan etkisi, ayrıca katı maddelerin ön kısmında (lazerle etkileşimin gerçekleştigi bölge) ikincil lazer tarafından önceden oluşturulan plazmaların hızlandırılan protonlar üzerindeki etkisi çalışılmıştır. 2 boyutlu EPOCH PIC simülasyonlarının sonuçları deneysel verilerin sonuçları ile karşılaştırılmış ve elde edilen bulguları destekledigi gözlemlenmiştir.

The net plankton community metabolism of oceanic surface waters is particularly important as it more directly affects the partial pressure of CO2 in surface waters and thus the air-sea fluxes of CO2. Plankton communities in surface waters are exposed to high irradiance that includes significant ultraviolet blue (UVB, 280–315 nm) radiation. UVB radiation affects both photosynthetic and respiration rates, increase plankton mortality rates, and other metabolic and chemical processes. Here we test the sensitivity of net community production (NCP) to UVB of planktonic communities in surface waters across contrasting regions of the ocean. We observed here that UVB radiation affects net plankton community production at the ocean surface, imposing a shift in NCP by, on average, 50% relative to the values measured when excluding partly UVB. Our results show that under full solar radiation, the metabolic balance shows the prevalence of net heterotrophic community production. The demonstration of an important effect of UVB radiation on NCP in surface waters presented here is of particular relevance in relation to the increased UVB radiation derived from the erosion of the stratospheric ozone layer. Our results encourage design future research to further our understanding of UVB effects on the metabolic balance of plankton communities.

The effects of temperature on performance of a grid-connected inverter, and also on a photovoltaic (PV) system installed in Thailand have been investigated. It was found that the maximum efficiency of the inverter showed 2.5% drop when ambient temperature was above 37°C. The inverter performed efficiently in November and December, the months of high irradiance, and monthly average ambient temperature of lower than 35°C, allowing relatively high system performance ratio in this period. Our results show that high temperature provides negative impacts not only on the PV modules, but also on the performance of the inverter. Thus, the effect of temperature on the inverter efficiency should be taken into account when predicting energy yield or analyzing losses of the PV systems—especially in high temperature regions.

The efficiency of solar photovoltaic (PV) panels is affected by its operating temperature. Having high irradiance produces high electrical output but also heats up the panel and reducing the panels efficiency. This study investigates the effect of cooling solar PV panels using 750g of paraffin wax as phase change material (PCM) applied to the back plate of a solar PV panel. The experiment is done at Kajang, Selangor, Malaysia. The result is reduction of up to 9.5°C, increase of up to 0.947W or 11.82% of electrical power output when compared to the panel without any PCM applied. The panel cooled with PCM also produced 4.69% more energy

Advances in LEDs allow construction of LED solar simulators for characterization of solar cells at moderate costs. Four single-color LED simulators and one multi-color LED simulators are constructed. High irradiance is obtained by employing high pulsing voltages to LEDs. Using the simulators electrical parameters and resistances of solar cell are made. Applying correction methods recommended in the IEC 891 Standard, results from the red and blue LED simulators and the Class AAA simulator are in good agreement.

Tropical climates (such as in Singapore) are characterised by fast-changing irradiance conditions due to high variations in cloud coverage. Different photovoltaic (PV) technologies possibly react differently to these variations of irradiance conditions, which in turn will also influence the module performance. In this study, a novel method is introduced to systematically investigate the fluctuating irradiance and its influence on module performance. Taking the Adnot clear-sky irradiance model as reference, the fluctuating irradiance is separated into high and low irradiance levels using the Typical Meteorological Day (TMD) irradiance values of 2011. These two irradiance groups are then analysed individually for the impact of the fluctuation frequency (defined via the number of minutes of constant irradiance) on the following module parameters: short-circuit current, module temperature and efficiency. The distribution of fluctuating irradiance over a whole year in Singapore and its impact on 5 different module technologies (monocrystalline Si, hetero-junction Si wafer, a-Si single junction, a-Si double junction and micromorph Si) are presented. The results show that the efficiency of wafer-based Si modules is not much influenced by the fast irradiance changes and dominated by the temperature effect at high irradiance. In contrast, Si-based thin-film technologies are stronger impacted by the fluctuations. Amorphous Si technologies show higher efficiencies at low irradiances, while micromorph Si modules react similar to monocrystalline Si at high irradiances, however with a slight drop in efficiency at low irradiances. This study gives valuable insights into the PV module response to varying irradiance.

Intense pulsed light (IPL) systems are incoherent and have high irradiance light systems which despite not being considered as part of the laser family (given the non-collimated and non-coherent nature of their emission) have proved their efficacy in interacting with tissues and are still subject to careful and objective evaluation. At first, IPL systems were poorly considered because of their nonspecific characteristics.

We studied stomatal conductance (gs) in leaves of cucumber plants (Cucumis sativus L., cv. Zozulya) subjected at early developmental stages to either short-term daily cooling (2 h at the end of night periods) or continuous chilling (12°C throughout the day and night). Irrespective of the irradiance during measurements, continuous chilling either lowered gs or had no effect, as compared to gs of control plants (23°C). In plants subjected to periodic short-term cooling, the gs was found to increase at low temperatures both at moderate and high irradiance; it also increased at high temperature (33°C) but only at photosynthetically active irradiance of 800 μmol/(m2 s). It is supposed that heat-loving plants, subjected to different types of low-temperature treatment, mobilize different mechanisms of stomatal regulation and employ different strategies of adaptation in response to low- and high-temperature treatments. The unusual behavior of stomata, manifested in stomatal opening at both low and high temperatures, extends the adaptive potential of plants subjected daily to short-term low-temperature treatments. This leads to a high level of photosynthesis, biomass accumulation, and supports high physiological activity in plants.

Rootless aquatic carnivorous Utricularia plants exude significant amounts of photosynthates into the trap fluid, where they have been shown to support complex microbial commensal communities. Using ion chro- matography, the composition of four groups of easily metabolised, carbon-rich organic compounds (sugars, sugar alcohols, amino acids and organic acids) was investigated in trap fluid collected from three aquatic Utricularia spe- cies, U. vulgaris, U. reflexa and U. stygia, for different trap ages, irradiance levels during plant growth and for expo- sure to periods of darkness. The total sum of the concentrations of the four groups of organic compounds in the trap fluid ranged within 14 - 42 mg l -1 in greenhouse-grown U. vulgaris, compared to 9.0 -14 mg l -1 in U. reflexa . The concentrations of organic compounds were significantly higher in younger traps than in the older traps of U. vulgar- is grown at high irradiance. Within the same trap age categories in U. vulgaris, the group concentrations of sugars, organic acids, and total sums of analysed compounds were significantly higher in plants growing at high irradiance when compared with those grown in the shade. Dark exposure of cut traps for 1- 2 d significantly decreased the concentrations of sugars and organic acids in the fluid. The total sum of organic compounds in traps of U. stygia grown outdoors (78.3 ± 19.2 mg l -1 ) was much higher than that in 'middle aged' traps of U. vulgaris (49.2 ± 4.2 mg l -1 ), grown under the same conditions. It may be concluded that the concentrations of organic compounds in the trap fluid of aquatic Utricularia are species specific, subject to rapid turnover and depend significantly on various endogenous (trap age) or exogenous factors (water chemistry, irradiance).

In this paper submerged photovoltaic systems (PVSs) are investigated with regard to the efficiency increase of PVS under high irradiance and ambient temperature; in particular, the optical and thermal effects are studied by means of experimental tests and mathematical models. The increment of efficiency through the cooling effects is evaluated. The PV panel performance of a submerged photovoltaic panel is investigated at different water depths. Experiments results on crystalline silicon panels are used to validate the models.

The accumulation of cold-induced dehydrin and proline was related to the frost tolerance (FT) in several Brassica species or cultivars. A dehydrin of molecular mass 47 kDa was detected in the leaves of an Ethiopian mustard (B. carinata) and a pair of dehydrins of similar molecular mass in the three (two winter, one spring) oilseed rape (B. napus) cultivars, when plants were maintained at 4 °C for one-month under two different irradiances. More dehydrin was accumulated in oilseed rape than in Ethiopian mustard under the high irradiance. A significant correlation was observed between leaf dehydrin content and FT, and no relationship between proline content and FT or between the proline and dehydrin contents. Protoplast-derived callus cells behaved differently from leaves sampled from intact plants, as they did not accumulate dehydrin and proline in response to cold stress.

To uncover the potential antioxidative role of anthocyanins in vivo in protecting photosynthetic tissues from photoinhibition, the effects of high irradiance [HI, 1300 μmol(photon) m -2 s -1 ] were studied using detached leaves derived from Arabidopsis wild-type (WT) and the mutant deficient in anthocyanin biosynthesis (tt3tt4). HI stress caused decreased chlorophyll content and photochemical efficiency, but increased cell-membrane leakage and contents of hydrogen peroxide and superoxide radical in the leaves of both Arabidopsis phenotypes, but the WT plants showed better HI tolerance than tt3tt4 mutant. HI caused a significant increase in the 1,1-diphenyl-2-picrylhydrazyl scavenging capacity in WT but not in the tt3tt4 mutant. The anthocyanins could not contribute substantially to light-shielding during the periods of HI stress, because the anthocyanin content in WT was very low and the colour of leaves was the same as in the tt3tt4 mutant. Thus, it was assumed that the better HI tolerance in WT was mostly related to the potential antioxidative role of anthocyanins.

Dynamic growth rate model has been developed to quantify the impact of hydrodynamics on the growth of photosynthetic microorganisms and to predict the photobioreactor performance. Rigorous verification of such reactor models, however, is rare in the literature. In this part of work, verification of a dynamic growth rate model developed in Luo and Al-Dahhan (2004) [Biotech Bioeng 85(4): 382-393] was attempted using the experimental results reported in Part I of this work and results from literature. The irradiance distribution inside the studied reactor was also measured at different optical densities and successfully correlated by the Lambert-Beer Law. When reliable hydrodynamic data were used, the dynamic growth rate model successfully predicted the algae's growth rate obtained in the experiments in both low and high irradiance regime indicating the robustness of this model. The simulation results also indicate the hydrodynamics is significantly different between the real algae culturing system and an air-water system that signifies the importance in using reliable data input for the growth rate model.

The rhythmic migration pattern of the dinoflagellate Ceratium furca is a result of ecological adaptation to avoid high irradiance. The high proportions of dividing cells at deeper depths are likely to be an ecological response to maintain their population away from the turbulence in the near-surface layer.

The aim of this work was to investigate the effect of high irradiance curing on resultant degree of conversion of 'flowable' resin composites and their counterpart higher viscosity paste materials.Five commercial flowable materials (Venus; Heraeus Kulzer, Synergy D6; Coltene, Premise; Kerr, Grandio; Voco and Gradia; GC Corp) and their counterpart higher viscosity restorative versions were tested. Specimens were cured with a halogen Swiss Master Light (EMS, Switzerland) using five different curing protocols with similar radiant exposure (18J/cm(2)): 400mW/cm(2) for 45s, 900mW/cm(2) for 20s, 1500mW/cm(2) for 12s, 2000mW/cm(2) for 9s and 3000mW/cm(2) for 6s. Degree of conversion (DC) was measured in real time by Fourier transform near infrared spectroscopy (FT-NIRS).Three- and subsequent two way ANOVA testing revealed significant differences (p≤0.02) with respect to "composite type" and "cure protocol" for DC for all 5 product comparisons. Supplementary one-way ANOVA also revealed significant differences between curing protocols (p0.05). The majority of higher viscosity resin composite paste materials exhibited similar DC regardless of curing protocol. However, a significant decrease in DC for specimens cured at 3000mW/cm(2) for 6s compared with 400mW/cm(2) for 45s was observed for the flowable materials, Grandio (41±0.36 and 62±1.15%, respectively) and Venus (44±0.44 and 67±0.44%, respectively). Conversely, other flowable materials exhibited little or no significant differences between curing modes. Generally, a higher degree of conversion was observed for flowables compared with their more viscous counterpart, except at high irradiance for those materials where a reciprocal relationship with exposure time was not observed.The validity of exposure reciprocity law and final degree of conversion depends on several factors, amongst which resin viscosity and filler content were important. Practitioners should be aware of the importance of resin composite constituents and irradiation protocols. Information on material composition and appropriate radiation sources by manufacturers may assist practitioners with the selection of appropriate curing protocols for specific material/light curing unit combinations with the aim of reducing the incidence of under-cured restorations and the clinical impact thereof.

7 p., 6 figures, 1 table and references, The widespread use of NO3− fertilization has had a major ecological impact. NH4+ nutrition may help to reduce this impact, although high NH4+ concentrations are toxic for most plants. The underlying tolerance mechanisms are not yet fully understood, although they are thought to include the limitation of C, the disruption of ion homeostasis, and a wasteful NH4+ influx/efflux cycle that carries an extra energetic cost for root cells. In this study, high irradiance (HI) was found to induce a notable tolerance to NH4+ in the range 2.5–10mM in pea plants by inducing higher C availability, as shown by carbohydrate content. This capacity was accompanied by a general lower relative N content, indicating that tolerance is not achieved through higher net N assimilation on C-skeletons, and it was also not attributable to increased GS content or activity in roots or leaves. Moreover, HI plants showed higher ATP content and respiration rates. This extra energy availability is related to the internal NH4+ content regulation (probably NH4+ influx/efflux) and to an improvement of the cell ionic balance. The limited C availability at lower irradiance (LI) and high NH4+ resulted in a series of metabolic imbalances, as reflected in a much higher organic acid content, thereby suggesting that the origin of the toxicity in plants cultured at high NH4+ and LI is related to their inability to avoid large-scale accumulation of the NH4+ ion., This work was supported by the Spanish MICIIN (grant nos. AGL2006-12792-CO2-01 and AGL2009-13339-CO2-02 [to P.A.-T.] and AGL2007-64432/AGR [to J.F.M.]). IA was supported by a doctoral Fellowship from the Public University of Navarre.

The studies of Rubisco characteristics observed during plant evolution show that the variation of the Rubisco specificity factor only improved by two times from cyanobacteria to modern C3 plants. However we note important variations of the ratio between the maximum rates of oxygenation and carboxylation (V(O)/V(C)). Modelling in vivo ¹⁸O₂ data in plant gas exchange shows that the oxygenation reaction of Rubisco plays a regulating role when the photochemical energy exceeds the carboxylation capacity. A protective index 'oxygenation capacity' is postulated, related to the ratio V(O)/V(C) of Rubisco, and hence to the sink energy effect of photorespiration. Analysing the trends of Rubisco parameters along the evolutionary scale, we show: (1) the increase of both V(C) and V(O); (2) the enhancement of CO₂ affinity; and (3) the rise in oxygenation capacity at the expense of the CO₂ specificity. Hence, the factors of evolutionary pressure have not only directed the enzyme towards a more efficient utilisation of CO₂, but mainly to positively use the unavoidable great loss of energy and assimilated carbon in the process of photorespiration. These observations reinforce the hypothesis of plant-atmosphere co-evolution and of the complex role of Rubisco, which seems to be selected to develop both better CO₂ affinity and oxygenation capacity. The latter increases the capacity of sink of photorespiration, in particular, during water stress or under high irradiance, the two conditions experienced by plants in terrestrial environments. These observations help to explain some handicaps of C4 plants, and the supremacy of CAM and C3 perennial higher plants in arid environments.

This study examined extensive patches of floating green macroalgal (Ulva prolifera) mats in the northern East China Sea (ECS) using satellite images from mid May through July 2008 and field observation made during early August 2008 cruise. It was previously reported that the massive macroalgal blooms occurred in the coastal areas of Qingdao in China. During our field survey, researchers noticed widely distributed floating patches of macroalgal mats ranging in size from tens of centimeters to a few hundred meters in diameter. Meteorological data in the northern ECS showed high irradiance, high airtemperature, and predominant southerly winds in summer. In the study area during the survey period, surface waters were characterized by the Changjiang Diluted Water (CDW) mass, which contained high concentrations of nitrate and phosphate. The internal transcribed spacer (ITS) sequence of U. prolifera found in the northern ECS was the same as those of U. prolifera sampled from Qingdao blooms, suggesting a possibility that U. prolifera found in two regions would be derived from the same origin. We suggest that U. prolifera in the nearshore Jiangsu Province drifted into the northern ECS and proliferated under favorable meteorological and oceanographic conditions during the summer of 2008.

When this Article was originally published, an old version of the associated Supplementary Information file was uploaded. This has now been replaced.

We have previously shown that juvenile leaves of Rhus glabra L. growing in a field setting were consistently 2–3 °C warmer than mature leaves during periods of high irradiance. An experiment was done to test the hypothesis that these differences in leaf temperature lead to increased photosynthetic temperature tolerance in juvenile leaves when compared with cooler, mature leaves. Significant differences were found between the leaf stages with detached juvenile leaves having a slightly higher T15 (the temperature causing a 15% drop in maximum photochemical efficiency) than mature leaves (43.5 vs. 41.1 °C). Additionally, measurement of the effect of temperature on actual quantum yield (ΦPSII) showed maximum activity at 35 °C for mature leaves, whereas juvenile leaves exhibited a broader temperature response with similar activities between 30 and 40 °C. The 2 °C difference in T15 roughly coincided with observed average differences between juvenile and mature leaf temperature we observed in the field, indicating that higher juvenile leaf temperature is a factor in promoting their enhanced temperature tolerance.

Rates of progression and transmission of black band disease (BBD) on the staghorn coral, Acropora muricata, were compared between months for seasonal in situ studies and between temperature treatments in experimental aquaria manipulations at Lizard Island on the Great Barrier Reef (GBR). In situ field experiments demonstrated that BBD progressed along branches approximately twice as fast (1.7–2.4 times) during the austral summer month of January (0.99 ± 0.04 cm/day) than in the cooler months of July (0.58 ± 0.04 cm/day) and May (0.41 ± 0.07 cm/day). Transmission of BBD between colonies was also accelerated in warmer months, with signs of infection becoming visible 1.2 days earlier in January compared to May. The greater seawater temperatures by ∼2 to 3°C and light intensities by up to 650 μE/m2/s in January, suggest that rates of progression and transmission of BBD are linked to one or both of these parameters. Manipulative experiments in summer provide corroborative evidence that elevated temperatures increase rates of BBD progression, with the disease progressing 1.3 times more rapidly in the 32°C elevated temperature treatment than in the 30°C ambient treatment (1.17 ± 0.06 cm/day versus 0.92 ± 0.07 cm/day; F2,6 = 7.66, P = 0.022). In contrast, although a trend for greatest BBD progression was measured in elevated temperature treatments of 29°C (0.46 ± 0.07 cm/day) and 31°C (0.52 ± 0.06 cm/day) in winter, these rates did not differ significantly (F3,7 = 1.72, P = 0.249) from those measured for the ambient 27°C treatment (0.37 ± 0.06 cm/day) or the field controls (0.41 ± 0.09 cm/day). The lower rates of BBD progression in the 31°C winter treatment (0.52 ± 0.06 cm/day) than in the 30°C (0.92 ± 0.07 cm/day) summer treatment, may have been a response to 28-fold decreased light irradiance in the former, suggesting that high irradiance in combination with elevated temperatures may promote progression of BBD. Results from this study indicate that the impact of elevated temperature on BBD progression is complex with a combination of environmental factors including temperature and light playing key roles in progression and transmission of the disease.

With the new and promising, but debated concentrating photovoltaics (CPV) technology it is aimed at lowering levelized cost of electricity (LCOE) through higher efficiency. The cost of CPV-generated electricity still remains as a major uncertainty issue, and that was aimed to tackle in this study. LCOE of CPV-generated electricity in Turkey and Chile was calculated and compared based on multiple assumptions from public sources. A comprehensive sensitivity analysis was carried out and it is openly presented in order to illustrate the impact of the initial assumptions to the results. It was found that PV is very competitive, but CPV still has some potential in high irradiance regions through technology improvements and improved financing.

Effects of irradiance and water flow on formation and growth of filamentous and spongy thalli of Codium fragile (Suringar) Hariot growing on vinylon threads were investigated at the laboratory culture. They showed clear differences in their irradiance and water flow requirements for their formation and growth. Spongy thalli were formed from the cultured filamentous thalli only at the high water flow velocity (10 cm s −1 ). Number of the spongy thalli remarkably increased with increasing irradiance because those at 10, 50 and 100 μmol m −2 s −1 reached 0, 2 and 76 thalli m −1 , respectively, by 10 weeks of culture. In contrast, filamentous thalli were formed from the cultured spongy thalli at 0 and 3 cm s −1 , and difference in irradiance had no effect on their formation. Growth of the spongy thalli greatly accelerated under the combination of the high irradiance and high water velocity (200 μmol m −2 s −1 and 10 cm s −1 ) because their relative growth rate in wet weight under the condition was two–four times higher than those at the other examined irradiances and water velocities. On the other hand, difference in water velocity had no effect on growth of the filamentous thalli under flowing water, and their growth decelerated at the high irradiance (200 μmol m −2 s −1 ). This demonstrates that water flow is a major factor controlling the formation of the spongy and filamentous thalli. The formation and growth of the spongy thalli surely occur under the combination of the high irradiance and fast flowing water. In contrast, the formation of the filamentous thalli occurs in the calm water, and their growth is inhibited under the high irradiance.

Biological systems are complex dynamical systems whose relationships with environment have strong implications on their regulation and survival. From the interactions between plant and environment can emerge a quite complex network of plant responses rarely observed through classical analytical approaches. The objective of this current study was to test the hypothesis that photosynthetic responses of different tree species to increasing irradiance are related to changes in network connectances of gas exchange and photochemical apparatus, and alterations in plant autonomy in relation to the environment. The heat dissipative capacity through daily changes in leaf temperature was also evaluated. It indicated that the early successional species (Citharexylum myrianthum Cham. and Rhamnidium elaeocarpum Reiss.) were more efficient as dissipative structures than the late successional one (Cariniana legalis (Mart.) Kuntze), suggesting that the parameter deltaT (T ºCair - T ºCleaf) could be a simple tool in order to help the classification of successional classes of tropical trees. Our results indicated a pattern of network responses and autonomy changes under high irradiance. Considering the maintenance of daily CO2 assimilation, the tolerant species (C. myrianthum and R. elaeocarpum) to high irradiance trended to maintain stable the level of gas exchange network connectance and to increase the autonomy in relation to the environment. On the other hand, the late successional species (C. legalis) trended to lose autonomy, decreasing the network connectance of gas exchange. All species showed lower autonomy and higher network connectance of the photochemical apparatus under high irradiance. Sistemas biológicos são sistemas dinâmicos complexos cujas relações com o ambiente apresentam importantes implicações sobre seus processos de regulação e sobrevivência. A partir destas interações pode emergir uma complexa rede de respostas que raramente são observadas pelas abordagens analíticas clássicas. Desta forma, o objetivo deste estudo foi testar a hipótese de que as respostas fotossintéticas de diferentes espécies arbóreas ao aumento da irradiância estão relacionadas às mudanças na conectância das redes de trocas gasosas e do aparato fotoquímico, assim como mudanças no grau de autonomia entre planta e ambiente. A capacidade de dissipação térmica avaliada por mudanças da temperatura foliar ao longo do dia também foi analisada, indicando que as espécies iniciais da sucessão (Citharexylum myrianthum Cham. e Rhamnidium elaeocarpum Reiss.) foram mais eficientes que a espécie tardia (Cariniana legalis (Mart.) Kuntze) como estruturas dissipativas. Isto sugere que o parâmetro deltaT (T ºCar - T ºCfolha) poderia ser uma ferramenta adicional para auxiliar na identificação das classes sucessionais de espécies tropicais arbóreas. Nossos resultados indicaram a ocorrência de um interessante padrão de resposta das redes e mudanças na autonomia quando as plantas foram submetidas à alta irradiância. Considerando a assimilação diária de CO2, as espécies tolerantes (C. myrianthum e R. elaeocarpum) tenderam a manter a conectância da rede de trocas gasosas estável e aumentar a autonomia em relação ao ambiente. Por outro lado, a espécie susceptível (C. legalis) à alta irradiância tendeu a perder autonomia, diminuindo a conectância da rede das trocas gasosas. Todas as espécies apresentaram menor autonomia e maior conectância da rede do aparato fotoquímico sob alta irradiância.

It has previously been shown that high intensity light irradiation at the leading tip of a moving benthic diatom can trigger reversals of cell direction. In this paper we have begun to characterise this response, determining the irradiance threshold and exposure durations needed to stimulate a response, as well as the amount of time that the effect of irradiation persists in the cell. Using irradiation levels of ca. 5 × 105 μmol m−2 s−1 (at 470 nm), we found that for Craticula cuspidata a reversal response requires a minimum exposure duration of 10 ms; exposures ≥ 100 ms stimulated 95–100% of cells to change direction. Using a single uninterrupted 2 s irradiation, cells show a threshold of response at ca. 1 × 103 μmol m−2 s−1. Using two irradiation pulses in rapid succession, we determined that cells can resolve individual light pulses as closely spaced as 1 ms. Similarly, when using longer total exposures broken up into a number of shorter light pulses, cell responses diminish rapidly if the pulses are s...