Increase In Light Transmittance Research Articles

Combined effects of nitrogen and sulfur fertilizers on chemical composition, structure and physicochemical properties of buckwheat starch

Buckwheat starch has attracted worldwide attention in the food industry as a valuable raw material or food additive. Nitrogen (N) and sulfur (S) are two nutrients essential to ensure grain quality. This study investigated the combined application of N fertilizer (0, 45 and 90 kg N ha−1) and S fertilizer (0 and 45 kg SO3 ha−1) on the chemical composition, structure and physicochemical properties of buckwheat starch. The results showed that increasing the fertilizer application decreased amylose content and starch granule size but increased light transmittance, water solubility and swelling power. The stability of the absorption peak positions and the decrease in short-range order degree suggested that fertilization influenced the molecular structure of buckwheat starch. In addition, increases in viscosity and gelatinization enthalpy as well as decreases in gelatinization temperatures and dynamic rheological properties indicated changes in the processing characteristics and product quality of buckwheat-based foods.

Micron-Smooth, Robust Hydrophobic Coating for Photovoltaic Panel Surfaces in Arid and Dusty Areas

Photovoltaic (PV) power generation is a clean energy source, and the accumulation of ash on the surface of PV panels can lead to power loss. For polycrystalline PV panels, self-cleaning film is an economical and excellent solution. However, the main reasons why self-cleaning coatings are currently difficult to use on a large scale are poor durability and low transparency. It is a challenge to improve the durability and transparency of self-cleaning thin films for PV panel surface against ash accumulation. Therefore, in this paper, a resin composite film containing modified silica components was designed and synthesized, mainly by the organic/inorganic composite method. A transparent hydrophobic coating with nano-micro planar structures was constructed, which primarily relies on the hydrophobic properties of the compound itself to build the hydrophobic oleophobic coating. The layer has a micrometer-scale smooth surface structure and high transparency, with a 0.69% increase in light transmittance compared with uncoated glass, and the durability is good. It is mainly applied to the surface of photovoltaic devices, which can alleviate the dust accumulation problem of photovoltaic panels in arid, high-temperature, and dusty areas and reduce the maintenance cost of them.

Effect of inorganic fillers on the light transmission through traditional or flowable resin-matrix composites for restorative dentistry

ObjectivesThe aim of this in vitro study was to evaluate the light transmission through five different resin-matrix composites regarding the inorganic filler content.MethodsResin-matrix composite disc-shaped specimens were prepared on glass molds. Three traditional resin-matrix composites contained inorganic fillers at 74, 80, and 89 wt. % while two flowable composites revealed 60 and 62.5 wt. % inorganic fillers. Light transmission through the resin-matrix composites was assessed using a spectrophotometer with an integrated monochromator before and after light curing for 10, 20, or 40s. Elastic modulus and nanohardness were evaluated through nanoindentation’s tests, while Vicker’s hardness was measured by micro-hardness assessment. Chemical analyses were performed by FTIR and EDS, while microstructural analysis was conducted by optical microscopy and scanning electron microscopy. Data were evaluated using two-way ANOVA and Tukey’s test (p < 0.05).ResultsAfter polymerization, optical transmittance increased for all specimens above 650-nm wavelength irradiation since higher light exposure time leads to increased light transmittance. At 20- or 40-s irradiation, similar light transmittance was recorded for resin composites with 60, 62, 74, or 78–80 wt. % inorganic fillers. The lowest light transmittance was recorded for a resin-matrix composite reinforced with 89 wt. % inorganic fillers. Thus, the size of inorganic fillers ranged from nano- up to micro-scale dimensions and the high content of micro-scale inorganic particles can change the light pathway and decrease the light transmittance through the materials. At 850-nm wavelength, the average ratio between polymerized and non-polymerized specimens increased by 1.6 times for the resin composite with 89 wt. % fillers, while the composites with 60 wt. % fillers revealed an increased ratio by 3.5 times higher than that recorded at 600-nm wavelength. High mean values of elastic modulus, nano-hardness, and micro-hardness were recorded for the resin-matrix composites with the highest inorganic content.ConclusionsA high content of inorganic fillers at 89 wt.% decreased the light transmission through resin-matrix composites. However, certain types of fillers do not interfere on the light transmission, maintaining an optimal polymerization and the physical properties of the resin-matrix composites.Clinical significanceThe type and content of inorganic fillers in the chemical composition of resin-matrix composites do affect their polymerization mode. As a consequence, the clinical performance of resin-matrix composites can be compromised, leading to variable physical properties and degradation.Graphical

Nanostructured Films of Ordered Fe Nanowires for High-Performance Transparent Electromagnetic Interference Shielding

Although metal nanowires (NWs), such as silver NWs, are ideal materials for flexible transparent electromagnetic shielding films, the challenge of obtaining absorptive shielding films with high transmittance and shielding efficiency (SE) still exists. To address this issue, this study used iron nanowires (Fe NWs) with excellent microwave absorbing properties to construct structures with ordered NW distributions. A series of polyethylene terephthalate (PET)/Fe NWs/poly (3,4-ethylenedioxythiophene) (PEDOT) electromagnetic interference (EMI) shielding films were prepared using the magnetic-field-induced orientation. The results demonstrate that the ordered Fe NW network structure can effectively overcome the problem of the trade-off between light transmittance and EMI SE. Specifically, at a Fe NW surface density of 201.78 mg/m2, the ordered PET/Fe NWs/PEDOT films demonstrated a 49.06% increase in light transmittance and a 32.94% increase in EMI SE (19.37 dB), compared to the films with randomly distributed Fe NWs. Furthermore, constructing a double-layer Fe NW network with a stagger angle of 45° at the same surface density increased the EMI SE by 73.2% relative to the monolayer-ordered Fe NW structure, reaching an SE value of 33.54 dB, while maintaining almost unchanged light transmittance. Additionally, the PET/Fe NWs/PEDOT films maintain 97.4% of EMI performance after 3000 bending cycles. Overall, this study provides a new approach for creating high-performance flexible transparent EMI shielding films.

Heat budget of lake ice during a complete seasonal cycle in lake Hanzhang, northeast China

The seasonal cycle of ice formation and breakup in Lake Hanzhang, China, was monitored during the winter of 2020–2021 using a float equipped with meteorological, hydrological, and optical instruments. This lake is located in mid-latitude cold and dry climate zone. We categorized the ice season into growth, equilibrium, and melting stages. The thickness of ice increased by an average of 0.7 cm day−1 at the bottom of the ice during the growth stage, and during the equilibrium stage it was stable at 35.0 ± 0.5 cm. During the melting stage, the internal melting dominated the ice ablation (1.0 cm day−1), followed by bottom melting (0.45 cm day−1) and surface melting (0.25 cm day−1). The net short-wave and long-wave radiative fluxes dominated the heat budget throughout the seasonal cycle. Sublimation was 1.1 cm, 73% of that in the growth stage. During the melting stage, the absorbed short-wave radiative flux promoted internal melting, enlarged the porosity, and enhanced further surface melting. The frequent negative air temperature during nighttime hindered the phase changes of the lake ice surface layer. In addition, the upward sensible heat flux in the lake water body increased from 7.8 to 14.5 W m−2 due to the increased light transmittance by lake ice. The heat balance and heat fluxes in ice-covered lakes in mid-latitude dry climate have rarely been explored. The results increase the knowledge of lake ice geophysics and are also useful for calibration and validation of lake ice models.

Effect of sintering process on the properties of transparent Al2O3

ABSTRACT Transparent Al2O3 is the most widely used transparent ceramic. The main factors affecting the transparency of Al2O3 are porosity and impurities. It was found that increasing the sintering temperature or extending the holding time can increase the grain size and reduce the porosity. Holding at 1800°C for more than 1 h is critical for grain growth and elimination of porosity. The increase in light transmittance mainly depends on the decrease in porosity, and the increase in grain size also helps. The increase in bending strength is inversely proportional to the increase in grain size. In a comprehensive comparison, the sample held at 1800°C for 2 h can achieve 87% light transmittance based on the bending strength of 322 MPa.

Development and characterisation of multifunctional surface coatings for photovoltaic panels

In this research, the efficiency of photovoltaic (PV) panel surfaces due to environmental pollution (dust, dirt and carbon dioxide etc.) results in the loss of output power. The self-cleaning, photocatalytic, anti-reflection and antibacterial coatings developed to reduce this effect were coated on glass surfaces by the sol–gel method, and the effects of the coatings made on the efficiency of PV panels were investigated. The optical and photocatalytic properties of the coatings made were characterised by contact angle measurement and the scanning electron microscopy, respectively. The panels coated with increased light transmittance on the PV panel surface showed self-cleaning properties, an anti-reflection effect and antibacterial surface formation. Of the coatings made on the panel surfaces, photocatalytic and anti-reflection effects were provided with titanium dioxide (TiO2) and silicon dioxide (SiO2) compounds, and an antibacterial surface was obtained with the diboron trioxide (B2O3) compound. Four panels covered with titanium dioxide, silicon dioxide, diboron trioxide and TiO2 + SiO2 + B2O3 and uncoated panels were compared. The PV panels are in the external environment, and the most efficient coating determination was made with the data received from the PV system assembly to measure the extra energy produced.

Room-temperature preparation of TiO2/graphene composite photoanodes for efficient dye-sensitized solar cells

Semi-transparent TiO2/graphene photoanodes are prepared at room temperature via an electrophoretic deposition method followed by compression and applied in dye-sensitized solar cells (DSSCs). Compression enhances the power conversion efficiency (PCE) of a DSSC, which constitutes up 18.4 times improvement compared to the uncompressed device. Incorporating graphene into the compressed film further improves the PCE by 28.8%. Simultaneously, compressing and graphene incorporating can greatly increase the film’s transmittance at long wavelengths, benefiting to the use of DSSCs as front unit in tandem solar cells. Scanning electron microscopy, porosity measurements, electrochemical impedance spectroscopy and open circuit voltage decay are performed to investigate the mechanisms. It is demonstrated that compressing a film can reduce the porosity and improve the inter-particle connections, which accounts for the increased light transmittance and enhanced PCE. The incorporated graphene can provide extra charge carrier pathway due to its excellent charge transport properties, as well as protect TiO2 nanostructure by preventing film cracking upon pressing due to its good flexibility, thus increases PCE to 6.75%, which, to our best knowledge, is the highest value among DSSCs with room-temperature prepared photoanodes.

Improved physical and mechanical properties of food packaging films containing calcium hydroxide as a CO2 adsorbent by stearic acid addition

Abstract Stearic acid, SA (0, 1, 2, 3, 4 and 5%) was used to functionalize the surface of CO2-adsorbent powders to improve the physical and mechanical properties of active packaging LLDPE films. SA functionalization of calcium hydroxide/zeolite adsorbents was confirmed by the generation of a COO− symmetric stretching peak at 1404 cm-1 in Fourier transform infrared spectroscopy spectra. SA acted as a surfactant to reduce the agglomeration of the adsorbents in the film. Fewer aggregates resulted in improved tensile strength, reduced water vapor transmission rate, and increased light transmittance, which in turn improved the physical and mechanical properties of the films. When these films were used as packaging for kimchi, they did not affect the ripening of the kimchi, and showed excellent CO2 adsorption performance. When more than 2% SA was added to the adsorbent, the mechanical and physical properties of the film improved, and the carbon dioxide adsorption performance was good.

Durability of microporous hybrid silica coatings: Optical and wetting properties

Bifunctional hybrid silica sol-gel coatings were synthesized, which showed both increased light transmittance and water-repellence. The as-prepared coatings of variable thickness (100–175 nm) were found to have low refractive index (1.250–1.275), high porosity (36%–42%), and maximum light transmittance up to 99.8%. Water-repellence of the surface was due to high water contact angle (90°) and low contact angle hysteresis (1–2°). Ellipsometric porosimetry and transmission electron microscopy measurements confirmed the microporous structure of the coatings. A systematic investigation for studying the durability and the deterioration of optical and surface properties was studied during aqueous soaking tests at different pH. During these experiments atomic force microscopy showed that the morphology of the surface did not change. The changes in the wetting properties were also confirmed by surface free energy measurements and an increase of the polar component was observed. The optical properties could be regenerated completely or partially after the soaking via heat treatment at 400 °C. The light transmittance of the samples remained high after the soaking, most likely due to the swelling of the solid matrix. The light transmittance and the water-repellent properties of the coatings showed long-term stability up to a year of storage.

Vibration motor-integrated low-cost, miniaturized system for rapid quantification of red blood cell aggregation.

Human red blood cells (RBCs) aggregate under low shear conditions, which significantly modulates flow resistance and tissue perfusion. A higher aggregation tendency in blood thus serves as an important clinical indicator for the screening of cardiovascular disorders. Conventional ways of measuring RBC aggregation still require large sample volumes, cumbersome manual procedures, and expensive benchtop systems. These inconvenient and high-cost measurement methods hamper their clinical applicability. Here, we propose a low-cost, miniaturized system to overcome the limitations of these methods. Our system utilizes a coin vibration motor (CVM) to generate a localized vortex for disaggregating RBCs in a disposable fluidic chip. The design of the chip was optimized with fluid dynamics simulations to ensure sufficient shear flow in the localized vortex for RBC disaggregation. The time-dependent increase in light transmittance from an LED light source through the plasma gap while the RBCs re-aggregate is captured with a CMOS camera under stasis conditions to quantify the level of RBC aggregation. Our CVM-based aggregometer was validated against a commercial benchtop system for human blood samples under physiological and pathological conditions, and showed an excellent performance with a high intraclass correlation coefficient of 0.995. In addition, we were able to achieve a rapid measurement (<4 min) with the CVM-based aggregometer, requiring only a 6 μl blood sample. These illustrate the potential of our CVM-based aggregometer for low-cost point-of-care diagnostics without compromising the measurement sensitivity.

Dynamic changes of the extracellular matrix during corneal wound healing

The extracellular matrix (ECM) confers transparency to the cornea because of the precise organization of collagen fibrils and a wide variety of proteoglycans. We monitored the corneal wound healing process after alkali burns in rabbits. We analyzed the location and expression of collagens and proteoglycans, the clinical impact, and the recovery of optical transparency.After the animals received both general and ocular topical anesthesia, the central cornea of the left eye was burned by placing an 8-mm diameter filter paper soaked in 0.5 N NaOH for 60 s. The eyes were evaluated under a surgical microscope at 1, 3, and 6 months after burning. At each time point, the clinical conditions of the burned and control corneas were observed. The arrangement of collagen fibers in the corneal stroma was visualized by Picrosirius-red staining, Gomori's silver impregnation and transmission electronic microscopy. Corneal light transmittance was also measured. Myofibroblasts presence was analyzed by immunohistochemistry. mRNA expression levels of collagen types I and III, lumican, decorin, keratocan and alpha-smooth muscle actin were determined by quantitative real-time polymerase chain reaction.One month after alkali burn, the ECM was disorganized and filled with lacunae containing different types of cells and collagen type III fibers in the wound area. Corneal opacities were present with attendant loss of light transmittance. Collagen and proteoglycan mRNA expression levels were up-regulated. After three months, wound healing progress was indicated by reduced corneal opacity, increased light transmittance, reorganization of collagen fibers and only collagen type I expression levels were at control levels. After six months, the wound area ECM morphology was similar to controls, but transmittance values remained low, denoting incomplete restoration of the stromal architecture.This multidisciplinary study of the stromal wound healing process revealed changes in corneal transmittance, collagen organization, myofibroblasts presence and ECM composition at 1, 3, and 6 months after alkali burning. Documenting wound resolution during the six-month period provided reliable information that can be used to test new therapies.

Nano-porous sol-gel derived hydrophobic glass coating for increased light transmittance through greenhouse

This paper reports an acid catalyzed sol-gel formulation with tetraethyl orthosilicate (TEOS) as a precursor for developing nano-porous anti-reflective coating on glass. The novelty of this formulation lies in judicious choice of ingredients. Oxalic acid, an unconventional acid catalyst created nano-pores of average diameter 1.25 μm due to entrapped carbon dioxide, which in turn increased the light transmittance by 7.01%. Carboxymethyl cellulose, a biopolymer fiber of 221 nm diameter imparted stability as well as hydrophobicity, without the need for high temperature annealing and hazardous trimethylchlorosilane (TMCS) treatment respectively. The fibrous stabilizer formed a top layer over two or three stacked silica nanoplates. The nanoplates had an average thickness 537 nm and inter-plate gaps of 119 nm, which also increased anti-reflectance property. The hardest pencil 9H failed to make any scratches on this coating, proving complete scratch-resistance. The invented formulation is eco-friendly and similar to solar cell technology.

Nitrogen modulation under chemostat cultivation mode induces biomass and lipid production by Chlorella vulgaris and reduces antenna pigment accumulation

Algal growth limitation in large-scale cultivation mostly results from high level synthesis of photosynthetic pigments, owing to self-shading effects and attenuation of light distribution. To overcome this problem, here we investigated the influence of nitrogen modulation on changes in antenna pigments as well as biomass and lipid production by Chlorella vulgaris under a chemostat continuous cultivation mode. The production of algal antenna pigments, including chlorophylls and carotenoids, was promoted in a total nitrogen (TN) concentration-dependent manner. Maximum algal biomass and lipid production were obtained from 70 mg/L of TN concentration along with a significant increase in light transmittance and reduction in antenna pigments. Furthermore, the composition of polyunsaturated fatty acids remarkably augmented at low TN concentrations. These results suggest that the reduction in algal antenna pigment synthesis via modulation of nitrogen concentration may serve as an effective strategy to enhance algal biomass and lipid production.

Light Transmittance by Organic Eyeglass Lenses According to their Class

The research concerns the transmission of electromagnetic waves with a wavelength corresponding to the visible part of the spectrum and part of the ultraviolet and infrared radiation range. Light transmittance through ocular lenses was tested using a UV-Vis spectrophotometer for the wavelength range 250-850 nm. Obtained results encourage reflection on the quality of the spectacle lenses produced. The obtained results do not confirm the assurances of producers about the increase in light transmittance in the range of wavelengths corresponding to the highest sensitivity of the human eye. In addition, lenses having UV protection coatings do not perform their function in a proper way. Eyeglass lenses of various classes were tested, equipped with various refining coatings. The effect of the number of coatings on the transmission of light through the lenses was not observed. Conducting and publishing studies such as those presented in this work may have a significant impact on the improvement of the quality of manufactured eyeglass lenses.

Acute sensitivity of astrocytes in the Substantia Nigra to oxygen and glucose deprivation (OGD) compared with hippocampal astrocytes in brain slices

The Substantia Nigra is a brainstem nucleus critical for movement control. Although its dopamine-producing neurons degenerate in Parkinsons disease, little is known of the acute effects of ischemia in this region. We recently reported that oxygen and glucose deprivation (OGD) in brain slices, an in vitro ischemia model, evokes a profound depolarization and swelling of GABAergic neurons in the Substantia Nigra pars reticulata (SNr), but not dopaminergic neurons in the Substantia Nigra pars compacta (SNc). The current study characterised the effects of OGD on nigral astrocytes, and compared these with the established responses of astrocytes in the CA1 hippocampal region. Intracellular recordings were made from astrocytes at the border between SNc and SNr subregions, in midbrain slices from postnatal day 21–23 rats. Immunoreactivity for astrocyte-specific proteins was also assessed. OGD evoked a slow, then fast depolarization of nigral astrocytes. The fast phase developed during the anoxic depolarization (indicated by a fast negative shift of extracellular DC potential and increase in light transmittance) and rapid increase in extracellular K+ concentration in the SNr. This biphasic response resembled the OGD-evoked depolarization of hippocampal astrocytes. However, unlike the partial repolarization seen in hippocampal cells after reperfusion with O2 and glucose, nigral astrocytes remained depolarized near 0 mV. In addition, immunoreactivity for glial fibrillary acidic protein-positive astrocytes markedly decreased in the Substantia Nigra after OGD, while in the hippocampus remained unchanged. These data indicate an acute post-ischemic withdrawal of astrocytic support in the Substantia Nigra, but not in the hippocampus.

Preferential Initiation and Spread of Anoxic Depolarization in Layer 4 of Rat Barrel Cortex.

Anoxic depolarization (AD) is a hallmark of ischemic brain damage. AD is associated with a spreading wave of neuronal depolarization and an increase in light transmittance. However, initiation and spread of AD across the layers of the somatosensory cortex, which is one of the most frequently affected brain regions in ischemic stroke, remains largely unknown. Here, we explored the initiation and propagation of AD in slices of the rat barrel cortex using extracellular local field potential (LFP) recordings and optical intrinsic signal (OIS) recordings. We found that ischemia-like conditions induced by oxygen-glucose deprivation (OGD) evoked AD, which manifested as a large negative LFP shift and an increase in light transmittance. AD typically initiated in one or more barrels and further spread across the entire slice with a preferential propagation through L4. Elevated extracellular potassium concentration accelerated the AD onset without affecting proneness of L4 to AD. In live slices, barrels were most heavily labeled by the metabolic level marker 2,3,5-triphenyltetrazolium chloride, suggesting that the highest metabolic demand is in L4 when compared to the other layers. Thus, L4 is the layer of the barrel cortex most prone to AD, which may be due to the highest metabolic demand and cell density in this layer.

Photocatalytic, self-cleaning, antireflective coating for photovoltaic panels: Characterization and monitoring in real conditions

A major problem in the operation of photovoltaic (PV) panels is the need for frequent maintenance and cleaning. In the present work, the effect of a self-cleaning, photocatalytic, antireflective glass coating on the efficiency of PV panels is investigated. The optical and photocatalytic properties of the coating were determined via UV–vis spectroscopy and degradation of organic pollutant Methylene Blue, respectively. Increased light transmittance in the visible light region and enhanced self-cleaning of the coated in comparison to the uncoated glass was demonstrated. The adhesion and the stability of the coating were tested in conditions of thermal fluctuations, UV weathering and sandblasting.The outdoor performance of coated and uncoated PV panels and arrays were monitored for several months at different climate conditions (Greece and China) in order the extra energy produced due to coating to be measured. An average 5–6% gain was found for both cases for the entire period of time. It was established that specific conditions such as intensity and angle of the incident light, occurrence of rain and sand storms influence significantly the power difference (ΔPm) between coated and uncoated PV panels. The increase of ΔPm under diffused light (cloudy day) and irradiation with high incident angle (morning, evening) reached ∼20% and 30% respectively, that were related to the anti-reflecting property of the glass coating. The coated surface showed better dust removal ability due to its superhydrophilicity (θ = 6°). The superior efficiency of coated panels as well as the low-cost spraying procedure without any post-deposition treatment render the nanocomposite SurfaShield G coating very important especially for northern regions with limited sunlight periods.

Effect of shade, opacity and layer thickness on light transmission through a nano-hybrid dental composite during curing.

The aim of this study was to investigate the effect of shade and opacity on the change in light transmission through different thicknesses of a nano-hybrid composite during curing. Twelve different shades of Venus Diamond (Heraeus Kulzer) were placed in disk shaped molds with thickness of 1, 2, and 3 mm (n = 3 per group) and cured with an LED light-curing unit. Initial, final and average irradiance, and the total amount of energy passing through the specimen were measured using the MARC Resin Calibrator at every 10s for a total of 40s. The translucency parameter and the contrast ratio were obtained using a chromameter. Results were analyzed with ANOVA/Tukey's test (α = 0.05). All shades and all thicknesses (up to 3 mm) experienced an increase in light transmittance during curing. The majority of the increase occurred during the initial 10s exposure, with significant increase occurring from subsequent exposures only in thicker specimens (i.e., 3 mm). The increase in irradiance at the bottom during curing was dependent on shade, with darker shades and greater depths of material showing less increase. For one specific resin composite formulation, an increase in translucency occurs as cure progresses, and the increase is enhanced for composites with greater lightness and lower contrast ratio. Composites demonstrate increased light transmittance as curing progress, which may improve depth of cure. The thicker composite showed the least increase in light transmission within the same shade. The increase in translucency is enhanced for composites with great lightness and lower contrast ratio.

Protective rain shields alter leaf microclimate and photosynthesis in organic apple production

Plastic rain shields reduce the leaf and fruit wetness and protect apple trees against major leaf diseases and hail damage. Shielding the trees may reduce incoming radiation, especially in the ultraviolet (UV) region of the light spectrum, and affect the microclimate and photosynthesis. In July of 2014 and June of 2015, we measured the leaf microclimate and photosynthetic performance using chlorophyll fluorescence and gas exchange in the apple cultivar ‘Santana’ grown in three treatments. In one treatment the trees were exposed to natural light and sprayed (control), and in two treatments the trees were unsprayed and shielded with a plastic film not permeable to UV-light (UV-) or a plastic film permeable to UV-light (UV+). The light transmittance was reduced in the shielded treatments, protecting the leaves from high solar irradiance during noon on sunny days, and avoiding afternoon depression of photosynthesis. Due to this, the leaf photosynthetic rates were often higher in the protected trees in comparison to the control trees at similar high light intensities, whereas there were no differences between treatments on cloudy days. The effect of the UV+ film on photosynthesis did not differ from the UV- film, except there was a tendency for higher values accompanied with increased light transmittance of the UV+ film. We conclude that a microclimate with more diffused light maintained the photosynthetic yield, despite a lower light level under the rain shields.