Total Light Energy Research Articles

Light quantity, not photoperiod terminates diapause in the crustacean Daphnia

AbstractWhile light controls dormancy occurrence in various groups of organisms, it may play different roles in its initiation and termination. Seasonally changing photoperiod is frequently used to announce cyclical events and trigger diapause initiation in advance of seasonal changes. A similar role for photoperiod has often been uncritically extended to diapause termination. In the present study we investigated the role of photoperiod and light quantity in diapause termination of resting eggs of a freshwater crustacean. In a few tests, a cohort of resting eggs of Daphnia magna were incubated under various light conditions. A short‐day photoperiod appeared as successful as a long day or artificial one in reactivating resting eggs. The hatching proportion was more related to total light energy applied than to its temporal pattern. The hatching proportion increased asymptotically from 0% reported after 6 h of light exposition or shorter, to 32% after 48 h of total light period of moderate intensity (55 μmol m−2 s−1). Longer light exposition did not increase hatching success considerably. A 15 times lower light intensity (3.5 vs. 55 μmol m−2 s−1) applied for a given period of time (96 h) resulted in a 3 times lower hatching success. Our results challenge the common opinion of the decisive role of photoperiod in diapause termination and support the alternative light‐energy threshold hypothesis. It seems that the resting eggs of D. magna do not monitor seasonal changes of the photoperiod but reactivate after completion of the refractory period and accumulation of a certain amount of light energy dose.

The Effect of Irradiation Distance on Light Transmittance and Vickers Hardness Ratio of Two Bulk-fill Resin-based Composites.

The aims of this study were to assess the light energy transmission and Vickers hardness (VH) ratio of two bulk-fill resin-based composites (RBCs) (Tetric EvoCeram and Filtek) cured at different distances between the light curing unit's (LCU) tip and the surface of the restoration (T-S) using either a Bluephase G2, Bluephase® 'turbo tip' or Bluephase Style LCU. Samples were cured from the top at T-S distances of 2mm, 6mm and 10mm for 20 seconds. A MARC-Resin-Calibrator™ recorded the transmitted irradiance reaching the bottom of the sample, in real time. The VH was measured at the top and bottom after 24h of dark storage. Both the total light energy (TLE) transmitted through the samples and their VH ratios were reduced with increasing T-S distance. At 10mm T-S distance, the VH ratio values of samples cured with Bluephase G2 LCU were significantly greater than the samples cured with the other LCUs while the samples cured with Bluephase® 'turbo tip' showed the lowest values. It can be concluded that TLE transmitted through bulk-fill RBCs and their VH ratio reduces with increasing T-S distance but the rate of decline is LCU dependent. Bluephase G2 was associated with the smallest light attenuation.

Field data and simulations to estimate the role of standby energy use of lighting control systems in individual offices

This paper investigates the effectiveness of lighting control systems (LCSs) in 57 individual office rooms of an educational building located in Lund, Sweden. The study uses simulations based on actual occupancy data. The simulations, performed with Daysim via the Honeybee interface, focus on the portion of standby energy use on total lighting energy use considering different combinations of LCSs and lighting power density (LPD). The results show that standby energy use accounts for about 30% of the total lighting energy use, but it can raise up to 55% in extreme cases. The portion of standby energy use increases with lower occupancy rates and lower LPD. As a conclusion, a complete switch-off of systems during unoccupied hours is fundamental to preserve savings from LCSs. In addition, the article argues that, when standby energy use cannot be minimized or eliminated, daylight design and very efficient light sources may reduce the need for complex LCSs in individual office rooms or the like.

Avoiding thermal injury during near-infrared photoimmunotherapy (NIR-PIT): the importance of NIR light power density.

Near-infrared photoimmunotherapy (NIR-PIT) is a newly-established cancer treatment which employs the combination of an antibody-photoabsorber conjugate (APC) and NIR light. When NIR light is absorbed by APC-bound tissues, a certain amount of heat is generated locally. For the most part this results in a subclinical rise in skin temperature, however, excessive light exposure may cause non-specific thermal damage. In this study, we investigated the potential for thermal damage caused by NIR-PIT by measuring surface temperature. Two sources of light, laser and light emitting diode (LED), were compared in a mouse tumor model. First, we found that the skin was heated rapidly by NIR light regardless of whether laser or LED light sources were used. Air cooling at the surface reduced the rise in temperature. There were no associations between the rise of skin temperature and tumor volume of the treated tumor, or APC concentration. Second, we investigated the extent of thermal damage to the skin at various light doses. We detected burn injuries 1 day after NIR-PIT, when the NIR light was at a power density higher than 600 mW/cm2. Successful treatments at lower power density could be achieved if the total light energy absorbed by the tumor was the same, i.e. by extending the duration of light exposure. In conclusion, this study demonstrates that thermal injury after NIR-PIT can be avoided by either employing a cooling system or by lowering the power density of the light source and prolonging the exposure time such that the total energy is constant. Thus, thermal damage is preventable side effect of NIR-PIT.

THE YIELD OF LETTUCE BREEDING LINE UNDER LED LAMPS IN WINTER GREENHOUSE IN THE NORTH

The lettuce (Lactuca sativa L.) is widely known and favorite vegetable crop among people. In Europe the main production of lettuce is performed on protected ground with application of artificial light sources. The artificially-lighted culture of salad became very actually acquired in the north. Previously, on the basis of multi-year studies on yield registration and experiments with different regimes of lighting we have defined the appropriate parameters of supplementary lighting for lettuce with sodium high-pressure lamps that provided the production in different seasons per year. The aim was to study the accumulation of biomass and yield quality in lettuce ‘Aphytsion’ being grown in winter rotation under light-emitting diodes lamps. The accumulation of biomass and yield quality was studied in ‘Aphytsion’, grown in winter rotation under lightemitting diodes lamps ECOLED-BIO-112-185WD120 UniversaLED (ООО ‘GK’ ‘CET’), Perm, in industrial greenhouse OOO ‘Prigorodniy’ at Syktyvkar city. The commodity output was obtained for two cycle of cultivation, November-December and December-January. Yield of foliage biomass was 2.4 kg/m 2 with flow density PAR (Photosynthetically active radiation) about 90 μmole quantum/m 2 s. at 20 W/m 2 with total light energy 54 MJ/m 2 supplied to plants from LED lamps. The plants produced about 0.5 g. of dry weight calculated on one mole of spent light energy. Energy efficiency of PAR was 3% that corresponded with data observed earlier with sodium high-pressure lamps. The conclusion was made about the suitableness of this type of light-emitting diode lamps for lettuce cultivation in winter rotation in first photic zone. It was recommended to increase duration of supplemental lighting up to 22-24 hours in December and up to 20-22 hours in January to improve the productivity and biological value of plant output. It enables to raise RAP income in plants by 35 %, on average for one cycle of cultivation.

Light energy attenuation through orthodontic ceramic brackets at different irradiation times.

To evaluate the total light energy (TLE) transmission through three types of ceramic brackets with, bracket alone and with the addition of orthodontic adhesive, at different exposure durations, and to compare the microhardness of the cured adhesive. Three different makes of ceramic brackets, Pure Sapphire(M), Clarity™ ADVANCED(P) and Dual Ceramic(P) were used. Eighteen specimens of each make were prepared and allocated to three groups (n = 6). MARC(®)-resin calibrator was used to determine the light curing unit (LCU) tip irradiance (mW/cm(2)) and TLE (J/cm(2)) transmitted through the ceramic brackets, and through ceramic bracket plus Transbond™ XT Light Cure Adhesive, for 5, 10 and 20 s. Vickers-hardness values at the bottom of the cured adhesive were determined. Statistical analysis used one-way analysis of variance (ANOVA); P = 0.05. TLE transmission rose significantly among all samples with increasing exposure durations. TLE reaching the adhesive- enamel interface was less than 10 J/cm(2), and through monocrystalline and polycrystalline ceramic brackets was significantly different (P < 0.05). Pure Sapphire(M) showed the highest amount of TLE transmission and Vickers-hardness values for 5, 10 and 20 s. Following manufacturer's recommendations, insufficient TLE may be delivered to the adhesive: increasing the exposure durations may be required when adhesive is cured through ceramic brackets. Clinicians are advised to measure the tip irradiance of their LCUs and increase curing time beyond 5 s. Orthodontic clinicians should understand the type of light curing device and the orthodontic adhesive used in their practice.

Study of energy transfer by different light curing units into a class III restoration as a function of tilt angle and distance, using a MARC Patient Simulator (PS)

ObjectiveThe MARC Patient Simulator (MARC PS) enables researchers to observe the influence of handling errors on the radiant exposure that is delivered by light curing units (LCUs). Changes in the tilt angle and distance of the light guide exit face in relation to the surface of the composite increment have a distinct effect on the total amount of light delivered during polymerization and may cause insufficient conversion of the material. Therefore, the aim of the present study was to determine the influence of the tilt angle and distance of irradiance on the efficiency of light application by recording the total amount of energy using the anterior tooth sensor of the MARC PS. MethodsThe influence of the tilt angle and distance of the light guide to the sensor surface on the delivered radiant exposure was examined for three different LCUs (Celalux 2 [C2], Bluephase [BP] and Translux Powerblue [TPB]). The measurements were performed for 20s each with five different tilt angles (α=0°, 5°, 10°, 15°, 20°) and nine different distances (L=1, 2, 3, 4, 5, 6, 7, 8, 9mm). ResultsFor all LCUs, a distinct influence of the tilt angle on the delivered amount of fluence was found. At 0° tilt the C2 delivered a total light energy of 38.55J/cm2. By increasing the tilt of the light guide the amount of energy applied significantly decreased. At 20° tilt a reduction by 31.2% of the original light fluence was recorded. However, the C2 was the most powerful LCU measured. Even under optimum measurement conditions, the BP delivered a fluence of only 14.8J/cm2. At a tilt angle of 20°, though, the light sensor still registered 92.7% of the original output power. Under the same conditions, the TPB delivered 81.4%.With increasing distance of the light guide exit face to the surface of the sensor all LCUs showed a significant loss in delivered light energy. At a distance of 2mm the C2 showed a reduction by 46.7%, whereas total fluence of BP and TPB were reduced by 3.8% and 4.8%, respectively. SignificanceThe choice of LCU and the application of an appropriate curing time are important for successful polymerization. Nevertheless, a perpendicular positioning of the light guide as close as possible to the surface of the composite increment is of essential importance in order to ensure sufficient delivery of light.

Bulk Fill Resin Composite Materials Cured with Single-Peak versus Dual-Peak LED LCUs

Abstract Introduction: Manufactures claim that recently introduced bulk fill materials (BFM) can be cured adequately in 4 mm increments. This requires adequate light energy to be transmitted through the material to ensure adequate polymerization at the bottom of the increment. Aim: To compare the total light energy transmission through three BFMs and bottom/top (B/T) surface Vickers hardness (VH) when cured with single-peak versus dual-peak LED LCUs. Methods and Materials: Samples (n=5) of two viscous BFMs, Tetric EvoCeram® Bulk Fill X-tra fil® [XF] flowable SureFil, were prepared. A conventional RBC, Tetric EvoCeram® was used as a control. Using MARC® RC, the irradiance delivered to top surface of samples was adjusted to 1200 mW/cm2. Samples were cured with singlepeak EliparTM S10 or dual-peakBluephase® G2 for 10 seconds and irradiance transmitted to the bottom surface measured. Samples were stored for 24 hours, prior to VH measurements B/T VH ratios were calculated. Statistically analysed used oneway ANOVA (α=0.05). Results: There was no statistically significant difference for B/T total energy transmission between materials except XF with EliparTM S10 (P&lt;0.001). Total energy transmission ranged from 0.7 J/cm2 to 1.5 J/cm2. There was no statistically significant difference for B/T VH ratios between materials (P&gt;0.05) when materials were cured with single-peak versus dual-peak LCU’s, XF&gt;SDR&gt;TEC&gt;TBF. TBF alone, did not reach the generally accepted B/T VH of 80%. Conclusions: Both single-peak and dual-peak LCU’s were equally effective for curing the studied bulk fill materials. Manufacture’s recommended total energy delivered to the top surface may not always be sufficient for effective curing.

Utilization of Scenedesmus obliquus biomass as feedstock for biodiesel and other industrially important co-products: An integrated paradigm for microalgal biorefinery

With an aim to design a microalgal biorefinery taking Scenedesmus obliquus as a model organism, a detailed sequential production protocol was developed for the first time for β-carotene, biodiesel, omega-3 fatty acids, glycerol and bioethanol from S. obliquus biomass. This research study not just projects S. obliquus as a feasible option for a microalgal biorefinery but also addresses the issue of economic and environmental sustainability by suggesting an optimized nutrient condition for maximizing benefits from the microalgal biomass. GC–MS technique has been used for the qualitative and quantitative analysis of the biodiesel obtained, and mass spectrophotometric technique has been used for quantitative analysis of the other co-products. The detailed process developed, yielded 0.06g of β-carotene, 38g of biodiesel, 2g of omega-3 fatty acids, 3g of glycerol and 17g of ethanol from 100g of S. obliquus biomass. A comparative analysis of the total light energy consumed and costs of nutrients incurred under autotrophic and mixotrophic modes has been presented. Additionally, more than twice the number of cultivation cycles per year, producing >12 fold higher biodiesel yield and >4 fold higher yield of co-products under optimized growth condition further highlights the significance of the strategy suggested.

Post Deposition Annealing Temperature Effect on White-Light Emitting of WOx Thin Film Stack on Si

Post Deposition Annealing Temperature Effect on White-Light Emitting of WOx Thin Film Stack on Si

Effect of curing time on Vickers microhardness of bulk-fill materials

Purpose: To compare the total light energy transmission (J/cm2) through bulk fill composite materials (BFMs) and Vickers microhardness (VH) when cured with a single peak LED LCU at two different exposure times. Methods and materials: Two viscous BFMs, Tetric EvoCeram Bulkfil (Ivoclar Vivadent) [TBF], XtraFil (Voco) [XF], and two flowable BFMs, Surefil SDR (Dentsply) [SDR], XtraBase (Voco) [XB] were prepared in 4mmdeep Delrin® rings (DuPont, Mississauga, Ontario, Canada). Tetric Evoceram [TEC], a conventional composite (Ivoclar Vivadent) was used as a control. Using MARC® RC, the irradiance delivered to the top surface of the samples was adjusted to either 800mW/cm2 and delivered for 2 s (16 J/cm2) or 1600mW/cm2 for 10 s (16 J/cm2). The irradiance (mW/cm2) transmitted to the bottom surface was measured with MARC® and the internal software converted this to J/cm2. Samples were stored post-irradiation in a dry, sealed, light-proof container at room temperature (21± 10 ◦C) for 24h. Three measurements were taken from both top and bottom surfaces of each sample using a Vickers Hardness TestingMachine (HM-200 Series, Mitutoyo Corporation, Tokyo, Japan) with 200g load applied for 10 s. Bottom to top (B/T) VH ratios were calculated. Data were statistically analysed using one-way ANOVA (a=0.05). Results: Table 1. For B/T total energy transmission, comparing each material when cured with 800mW/cm2 × 20 s versus 1600mW/cm2 × 10 s, there was extremely statistical significant difference for all materials used with more total energy transmitted at 800mW/cm2 × 20 s (P TEC>XF>TBF>XB. For B/T VH ratios. Comparing each material when cured with 800mW/cm2 × 20 s versus 1600mW/cm2 × 10 s, XB and TEC showed extremely significant difference with higher B/T VH ratio when cured with 800mW/cm2 × 20 s (P 0.05). XB did not reach the generally accepted [1] 80% B/T VH ratio (74.8% @ 800mW/cm2 × 20 s, 64.0% @ 1600mW/cm2 × 10 s). Comparing B/T VH ratios ranged from 74.8% to 91.6%(TEC>XF>SDR>TBF>XB @800mW/cm2 × 20 s) and ranged from 64.0% to 88.3% (XF>SDR>TEC>TBF>XB @1600mW/cm2 × 10 s).

The Interference of Bioenergetics in Photosynthesis and the Detection of Heavy Metals

Photosynthesis is one of the most prominent bioenergetics processes, where the energy from the sun is trapped and converted into carbohydrates. The process occurs in autotrophic organisms, such as plants, algae, and cyanobacteria not only producing O 2 through light reaction, but fixes CO 2 to produce carbohydrates in dark reaction [1]. Tapping on 1% of the total light energy from the sun that reaches earth, photosynthesis fuels the energy needed by living organisms on earth. First step in photosynthesis, the light from the sun is captured by chlorophyll and other photosynthetic pigments. When the light is absorbed, electrons are promoted to higher orbital, thus increases the possibility of these electrons to be transferred to other acceptors. The moving of electrons from one acceptor to another is a continuous oxidation-reduction chain reaction, which at the end, the energy received from the light is converted into chemical energy- carbohydrate. However, not all the energy captured by photosynthetic pigments is channeled into carbohydrate synthesis. A portion of the energy is converted to heat and been released into environment [2] on the other hand a small amount of energy dissipated in the form of fluorescence emission. All the channels that the photosynthetic organisms used to dissipate the energy absorbed from the sun affect each other e.g. reduce in photosynthesis might causes the increase of fluorescence emission [3]. The presence of heavy metals interferes photosynthesis pathway through several mechanisms [4-7]. Although a few heavy metals e.g. Cu and Zn are required in low concentration to maintain the normal metabolism of the photosynthetic organisms, the inhibition of photosynthesis is obvious at high concentration of heavy metals. The inhibition of photosynthesis can be indicated by reduce in oxygen production and the increase in fluorescence emission. Both of these physiological changes have been utilized by scientists as indicators of the presence of heavy metals in environment [8-12]. These biological integrated indicators are commonly being referred as biosensor. Biosensor is defined as analytical tools combining biological component, transducer, and reader together [13]. The biological components ranges from cells to biological molecules e.g. amino acids and deoxyribonucleic acids, which responses to specific target compounds, with the transducers responsible to translate the biological responses to electronic signal that can be captured and displayed through the readers. To date, several cell-based biosensors has been developed, with the interference of bioenergetics in photosynthesis has been utilized as signal-generating parameter. Nevertheless, the connection of photosynthesis to the sensing application has become one of the important stepping stones in the exploration to use other bioenergetics pathways to serve the sensing purposes.

The Effect of Nutrient Enrichment on three Species of Macroalgae as Determined by Photoacoustics

The efficiency of photorophs in storing light energy in products of photosynthesis, or the quantum yield of the process, determines the flux of energy into any ecosystem, and is readily affected by any stress factor, physiological or environmental. Hence it can serve as a sensitive reporter of imminent ecosystem perturbation. Current methods of estimating that parameter are either indirect, or tedious and labor consuming. The photoacoustic method is based on the direct sensing o f the variable fraction of light energy degraded to heat, that wh ile absorbed by the plant cells or tissue, failed to be stored as energy rich photosynthate. Algae are the main primary producers in all water bodies, marine, freshwater, natural and man made, and as such they provide the energy basis for all aquatic ecosystems. The bio mass and vitality of the algal population responds rapidly to seasonal changes in environmental factors such as temperature, light, vertical mixing, eutrophication, pollution and nutrient limitation. Typical processes resulting fro m human activit ies such as non-point sources of agrochemicals, sewage outflows, and effluents from food, animal and other chemical processing industries as well as fro m urban and rural runoff, contribute considerable amounts of nitrogen and phosphorous, in many cases in addition to heavy metals, to natural and artificial water bodies. In this study, we examined by the photoacoustic method the effects of enrich ment by nitrogen and phosphorus on the photosynthetic efficiency of three co mmon Mediterranean seaweed species which were co llected fro m the field. The application developed by us, allows the rapid and direct determination of phytoplankton photosynthetic activity, by relating the energy stored photochemically to the total light energy absorbed by the plant material. The aim of this work was the examination of the applicability of the photoacoustic system to ecological work with macroalgae, since until now it has been successfully used only in homogenous phytoplankton cultures.

The energy performance of the Central Sunlighting System

This article presents a simulation study to predict the energy performance of the Central Sunlighting System (CSS) installed in open-plan offices. Several simulation tools are combined to conduct the simulations. SkyVision calculates the daylight luminous flux and the lighting and solar heat gains of the CSS. A set of coefficients pre-calculated using Radiance relates the desktop illuminances to the CSS luminous fluxes. DaySim is used to compute the daylight illuminance from the perimeter windows. ESP-r is used to compute the heating and cooling energy use of the office spaces. The results show that the CSS may save a significant amount of energy in North American climates. Energy savings from the combination of daylighting from windows and the CSS for typical, four-cubicle, open-plan offices range from 44% to 57% for lighting, 8% for cooling and from 14% to 23% for the total (lighting, cooling and heating) energy.

Biohydrogen production by Rhodobacter capsulatus in solar tubular photobioreactor on thick juice dark fermenter effluent

Abstract The purpose of this study was to operate a pilot scale solar tubular photobioreactor (90 L) for photofermentative hydrogen production from thick juice dark fermenter effluent (DFE) by photosynthetic purple-non-sulfur bacterium, Rhodobacter capsulatus. The tubular photobioreactor was equipped with internal cooling tubes for effective temperature control, which is essential for stable, long-term operation. The photobioreactor was operated in fed-batch mode throughout September 2009 in Ankara, Turkey. R. capsulatus had a rapid growth with a specific growth rate of 0.025 h−1 in the exponential phase. The growth was modeled and the parameters were compared with the results obtained in artificial medium. An exponential relationship was found between daily specific growth rates during fed-batch operation and daily total light energy received. The average molar productivity calculated according to daylight time was 0.15 mol H2/(m3 h). The yield obtained was 0.4 mol H2/mol acetic acid consumed. The hydrogen yield factor was related to the daily total light energy received. Acetic acid utilization for different metabolic pathways was investigated. Maximum COD removal efficiency throughout the operation was calculated as 68%. This study showed that sequential operation of dark and photofermentation is a promising route to produce biological hydrogen from thick juice.

Combination of Fospeg-IPDT and a natural antioxidant compound prevents photosensitivity in a murine prostate cancer tumour model

The aim of the present research was to investigate the potential use of a natural compound rich in antioxidant agents, derived from Pinus halepensis (P. halepensis), to prevent PDT induced photosensitivity. The present research progressed in two levels. The first one evolved the optimization of Fospeg-interstitial photodynamic therapy (IPDT) in a prostate cancer animal model. In the second one, P. halepensis bark extract, was evaluated for its potential use to prevent photosensitivity. Two sets of experiments were performed, IPDT only and IPDT in the presence of antioxidant. For both of them, Fospeg was administrated intravenously to SCID mice bearing prostate cancer, followed by IPDT after 6 h. For the IPDT+antioxidant experiments, P. halepensis was injected intratumourously 1 h prior the tumour illumination. Treatment outcome was monitored twice a week by an imaging system and by measuring tumour dimensions using a caliper. Photosensitivity was assessed by monitoring erythema of the tail using the imaging system. IPDT with Fospeg and 15 J total light energy is a therapeutic scheme that can eliminate tumours in the murine model of prostate cancer. Two months after complete tumour remission no tumour recurrence was observed. Also, the cosmetic outcome of the research was excellent. The major drawback of this treatment scheme was that 90% of the animals developed photosensitivity. The addition of P. halepensis bark extract resulted in prevention of the photosensitivity, leaving PDT outcome unaffected. The combined use of PDT and the used antioxidant agent could broaden the implementation of photodynamic therapy, by eliminating photosensitivity.

Association Between the Efficacy of Half-Dose Photodynamic Therapy With Indocyanine Green Angiography and Optical Coherence Tomography Findings in the Treatment of Central Serous Chorioretinopathy

To determine the efficacy of half-dose photodynamic therapy (PDT) in relation to indocyanine green angiography (ICGA) and optical coherence tomography (OCT) findings for treating chronic central serous chorioretinopathy (CSC). Observational case series. Thirty-eight eyes of 37 patients with chronic CSC and symptoms for at least 6 months were recruited. PDT was performed using half the normal dose of verteporfin. A total light energy of 50 J/cm(2) over 83 seconds was delivered to the area of choroidal hyperfluorescence as observed on ICGA. The resolution of the subretinal fluid and recurrence rates were assessed in relation to the different degrees of choroidal hyperfluorescence and the distribution of fluid in the neuroepithelium, namely subretinal fluid or posterior retinal cystoid degeneration. After half-dose PDT a dry macula was obtained in 86.8% and 92.1% of the eyes at 1 month and at the last follow-up (14.2 ± 5.8 months) respectively. ICGA at baseline showed intermediate and intense hyperfluorescence in 39.4% and 60.5% of the eyes respectively. All eyes with intermediate hyperfluorescence had only subretinal fluid at OCT and a dry macula was obtained in 87% and 100% at 1 month and at the last follow-up after half-dose PDT. In the intense hyperfluorescence group, 82.6% and 17.4% of the eyes had subretinal fluid only or both subretinal fluid and posterior retinal cystoid degeneration respectively. In the intense hyperfluorescence group with subretinal fluid only, a dry macula was obtained in 89.5% and 100% of the eyes at 1 month and at the last follow-up respectively. In the intense hyperfluorescence group with both subretinal fluid and posterior retinal cystoid degeneration, a dry macula was obtained in 75% and 25% of the eyes at 1 month and at the last follow-up respectively. Overall, of the 23 eyes with intense hyperfluorescence, 20 eyes (87%) had a dry macula starting from 1 month for the entire follow-up period. The half-dose PDT success rate in eyes with chronic CSC depends also on the distribution of fluid in the neuroepithelium. Half-dose PDT might not be effective or the recurrence rate might be high in eyes with posterior retinal cystoid degeneration.

Characterization of energy conversion of Synechococcus sp. PCC7942 under photoautotrophic conditions based on metabolic flux and chlorophyll fluorescence analysis

Energy conversion efficiency of photoautotrophic microalgae plays an important role in the utilization of light energy for cell growth and production of metabolites. To understand the utilization of light energy, Synechococcus sp. PCC7942 was cultivated at different incident light intensities of 15.8, 47.3, and 94.6 μmol/m2/sec in continuous culture. The influence of light on the carbon and energy metabolism of microalgae was investigated by combining metabolic flux analysis (MFA) and chlorophyll fluorescence analysis (CFA). Results showed that the yields of biomass based on ATP (Y ATP) and total light energy (Y E) both declined with increasing light, and the maximal values of Y ATP and Y E were estimated to be 4.73 g/mol-ATP, and 17.10 × 10−3 g/kJ respectively, at the examined conditions. The overall efficiency of energy conversion against total absorbed energy changed with the varying irradiances. However, the actual conversion efficiency of total energy based on CFA was almost constant, regardless of the different irradiances used in the present study.

Impact of light quality on leaf and shoot hydraulic properties: a case study in silver birch (Betula pendula)

Responses of leaf and shoot hydraulic conductance to light quality were examined on shoots of silver birch (Betula pendula), cut from lower ('shade position') and upper thirds of the crowns ('sun position') of trees growing in a natural temperate forest stand. Hydraulic conductances of leaf blades (K(lb) ), petioles (K(P) ) and branches (i.e. leafless stem; K(B) ) were determined using a high pressure flow meter in steady state mode. The shoots were exposed to photosynthetic photon flux density of 200-250 µmol m⁻² s⁻¹ using white, blue or red light. K(lb) depended significantly on both light quality and canopy position (P<0.001), K(B) on canopy position (P<0.001) and exposure time (P=0.014), and none of the three factors had effect on K(P) . The highest values of K(lb) were recorded under the blue light (3.63 and 3.13×10⁻⁴ kg m⁻² MPa⁻¹ s⁻¹ for the sun and shade leaves, respectively), intermediate values under white light (3.37 and 2.46×10⁻⁴ kg m⁻² MPa⁻¹ s⁻¹ , respectively) and lowest values under red light (2.83 and 2.02×10⁻⁴ kg m⁻² MPa⁻¹ s⁻¹, respectively). Light quality has an important impact on leaf hydraulic properties, independently of light intensity or of total light energy, and the specific light receptors involved in this response require identification. Given that natural canopy shade depletes blue and red light, K(lb) may be decreased both by reduced fluence and shifts in light spectra, indicating the need for studies of the natural heterogeneity of K(lb) within and under canopies, and its impacts on gas exchange.

Sunlight Photo-Assisted TiO2-Based Pilot Plant Scale Remediation of (Simulated) Contaminated Aquatic Sites

A tubular-type solar photoreactor system powered by commercial solar panels and consisting of six 20-tube modules (Pyrex glass) to mimic a pilot plant scale configuration was designed and constructed to examine the remediation of simulated wastewaters contaminated with various classes of organic pollutants such as endocrine disruptors (e.g. bisphenol A), anionic surfactants (sodium butylnaphthalenesulfonate and sodium dodecyl- benzenesulfonate), herbicides (e.g. 2,4-dichlorophenoxyacetic acid) and a commercial dishwasher detergent. Photo-oxidative processes followed first-order kinetics expressed in terms of the total light energy (in kJ) that impinged on the photoreactor. The influence of TiO₂ loading and circulation flow rate of the wastewaters on the dynamics of the photo-oxidation to mineralization (loss of total organic carbon, TOC, or formation of sulfate ions) was investigated. The optimal operational parameters were: TiO₂ loading, 2 g L⁻¹; circulation flow rate, 7.5 L min⁻¹. On a sunny day, near- quantitative mineralization of the contaminants was achieved after only 4 h of irradiation that corresponded to an accumulated energy of ca 1380 kJ.