Spectral Light Transmission Research Articles

Implications of Wound Healing on Subcutaneous Photovoltaic Energy Harvesting.

Cardiac pacemakers must be regularly replaced due to depleted batteries. A possible alternative is proposed by subcutaneous photovoltaic energy harvesting. The body's reaction to an implant can cause device encapsulation. Potential changes in spectral light transmission of skin can influence the performance of subcutaneous photovoltaic cells and has not yet been studied in large animal studies. Subcutaneous implants measuring changes in the light reaching the implant were developed. Three pigs received those implants and were analyzed for seven weeks. Spectral measurements with known irradiation were performed to identify possible changes in the transparency of the tissues above the implant during the wound healing process. A histological analysis at the end of the trial investigated the skin tissue above the subcutaneous photovoltaic implants. The implants measured decreasing light intensity and shifts in the light's spectrum during the initial wound healing phase. In a later stage of tissue recovery, the implants measured a generally reduced light intensity compared to the healthy tissue after implantation. The spectral distribution of the measured light at the end of the trial was similar to the first measurements. The histological analysis showed subcutaneous granulation tissue formation for all devices. The varying reduction of light intensity reaching the implants means that safety margins must be sufficiently high to ensure the power. At the end of the wound healing process, the spectral distribution of the light reaching the implant is similar to healthy tissue. Optimizations of spectral sensitivity of photovoltaic cells are possible.

Sunburn control by nets differentially affects the antioxidant properties of fruit peel in ‘Gala’ and ‘Fuji’ apples

Netting has been widely used in recent years to protect apple fruit from solar injury. There is little information on the biochemical aspects underlying the effectiveness of netting against sunburn in apples. The objective of this study was to quantify the effects of netting on polyphenols, anthocyanins, and antioxidant activity in apples with different sunburn degrees in terms of fruit peel color variation. Orchards of ‘Gala Brookfield’ and ‘Fuji Raku Raku’ apples were covered in red and pearl nets (providing 20% shading), respectively. Uncovered trees served as controls for the experiments. Spectral light transmission was measured under the nets from 350 to 1700 nm. Photosynthetically active radiation (PAR), ultraviolet radiation (UV), and fruit surface temperature (FST) were evaluated from 20 to 175 day after full blooming. Red netting increased the amount of red (600–700 nm) and blue (400–500 nm) wavelengths of the visible spectrum. Both red and pearl nets reduced infrared (900–1700 nm) transmission by 8%, which resulted in a decrease around 5 °C in FST. Similarly, PAR radiation was reduced by 25 and 21% on average, while the reduction in UV radiation reached 29 and 25% with red and pearl netting, respectively. In moderate (browning; SB-3) and severe (browning with necrosis; SB-4) damage categories, sunburn decreased 15% in ‘Gala Brookfield’ under red netting, and only 4% in ‘Fuji Raku Raku’ under pearl netting. In ‘Gala Brookfield’, red netting significantly increased anthocyanin content and ferric ion-reducing antioxidant power (FRAP) antioxidant capacity for the SB4 sunburn category. In contrast, pearl netting significantly reduced the amount of polyphenols, anthocyanins, and the FRAP antioxidant capacity in SB-4 sunburn group of ‘Fuji Raku Raku’ apples. Collectively, our results suggest that sun protection provided by netting result in changes in the composition and antioxidant capacity of fruit peels, whose response varies depending on the cultivar and type of net used.

Apple sap flow in different light environments

Three photoselective, 50% shading, nets (red, white, blue) and a black, 20% shading, commercial hail net (CTRL) were placed on 6 apple trees (Malus domestica 'Rosy Glow') each, during summer 2016. Total and specific sap flows were monitored, using the thermal balance approach, on 4 branches per treatment at different phenological stages. In addition, daily leaf and stem water potentials as well as leaf gas exchange were determined three times during the season. During the warmest periods, trees under the red net showed the highest branch sap flow, followed by the CTRL, the blue, and the white. The higher sap flow under the red net might have been due to a steeper temperature rise during the morning hours. In fact, spectral light transmission under this net was higher in the infrared region compared to the blue and the white. Water potential data support this hypothesis, as lower values were recorded under the red net. However, leaf transpiration and stomatal conductance were not different among the four treatments. This discrepancy between leaf gas exchange and sap flow may be explained by the fact that the former was measured on full light leaves, whereas the latter integrated the whole branch transpiration, thus also transpiration from shade leaves. Under the red net these leaves might have had higher transpiration due to the higher infrared absorption, thus explaining the higher sap flow recorded under this net. On the other hand, the white net showed lower water use, probably due to the benefit of shading. This work shows how photoselective nets can significantly alter the canopy water use and suggests the possibility to use them as tools to improve orchard water use efficiency.

High contrast electrochromic iris.

We present a non-mechanical microiris based on two complementary electrochromic (EC) materials, namely viologens and phenozines, with an almost neutral spectral behavior. Measurements concerning the spectral light transmission, modulation transfer function, and response time validate that the optical performance of the EC-iris is comparable to that of a classical blade iris. The time constant is limited due to diffusive mass transport of the molecules, but can be reduced by a short voltage pulse. The current controlled transmission of the EC-material renders the individual control of each iris segment without crosstalk possible, allowing its usage as tunable spatial filter.

MATERIAL TECHNOLOGY OF DIFFUSE GREENHOUSE COVERING MATERIALS - INFLUENCE ON LIGHT TRANSMISSION, LIGHT SCATTERING AND LIGHT SPECTRUM

During the last years it has been shown that diffuse light is advantageous for many greenhouse crops. Modern greenhouse covering materials are able to transform direct sunlight into diffuse light. After entering the greenhouse sunlight is scattered and penetrates into the crop, where it is absorbed and used for photosynthesis. Experimental research with different crops (e.g., tomato, cucumber, roses) over the last years showed an improved production under diffuse light conditions, expressed in growth rate or yield of up to 10% in The Netherlands. In the last five years different glass producers have put a lot of effort in devel-opment of diffusing greenhouse covering materials. Different structures have been developed and applied on glass for greenhouse application. Glass surface treatments result in regular or irregular patterns on glass such as matt/matt, prismatic, satin, texture and v-grooves. Next to that micro structures are combined with nano-structures, such as anti-reflection treatments (AR), in order to improve light transmission into the greenhouse. It can be shown that material development was able to improve hemispherical light transmission of diffuse glasses by at least 5% in 2013 compared to before 2007, glasses with larger hemispherical transmission and highly diffusing properties are available. Earlier an evaluation method for diffuse materials had been proposed. That method is mainly based on a measurement of the so-called hemispherical light trans-mission and haze. New possibilities in material technology and increasing knowledge of the relation of diffuse light and crop reactions caused a need to extend evaluation methods. Measuring spatial distribution of transmitted light is suggested next to measuring angular and spectral light transmission. Different new diffuse materials of different producers are measured and evaluated. The results show that diffuse glasses differ in haze and hemispherical light transmission. As well, the choice of basic glass material as the type of anti-reflection treatment are main causes of light spectrum changes. Diffuse structures alone do not cause differences in spectral light transmission. Different structures and AR treat-ments result in different angular light transmission, which explains differences in hemispherical light transmission. Measurements of spatial light transmission show that many diffusing glasses only cause a narrow light scattering pattern so far. Full Text (PDF format, 1057673 bytes)

Spectral Light Transmission Measure of Metal Screens for Glass Façades and Assessment of their Shading Potential

Metal mesh grids and perforated screens are used in new and renovated buildings as an external second skin for the building envelope; to enhance architecture design, to filter daylight and to reduce solar gains. Their effectiveness as shading devices depends on their geometry, texture and application.In the first part of the paper six types of shadings with similar transparencies, depending on geometry and openness factor of metal mesh grid and perforated screen, were investigated. Integrating sphere measurements were collected to obtain spectral optical properties of the shading devices. The optical properties were measured for incidence angles between normal and 60°with a step of 15°. The data collected were integrated to obtain visible and solar transmittance values in accordance with ISO 9050.In the second part of the paper a parametric study on spacing and thread dimension of metal mesh grids was done using Window 6.2 models to evaluate their shading potential, defining annual different shading profiles depending on shading geometry, latitude and orientation.A conventional office unit with a curtain wall façade with a metal mesh grid shading system was modeled in TRNSYS to evaluate the solar gain profiles and their effects on the energy balance of the office unit, under different weather conditions.

Spectral Light Transmission Measure and Radiance Model Validation of an innovative Transparent Concrete Panel for Façades

This paper presents an approach to measure, characterize and simulate photometric performances of light transmission efficiency of an innovative transparent concrete panel for façades. The transparency was obtained by a texture of PMMA resin insertions in the fiber reinforced concrete panel. In the first part of the paper integrating sphere measurements were collected to derive spectral optical properties of the panel. The optical properties of a specimen were measured for incidence angles between normal and 60° and the spectral results were reported. The data collected during the measures were used to: create and validate a simplified Radiance model of the panel and to optimize simulation parameters to estimate properly the total internal reflections effects thought the PMMA resin insertions.

Individual variation in rod absorbance spectra correlated with opsin gene polymorphism in sand goby (Pomatoschistus minutus)

SUMMARY Rod absorbance spectra, characterized by the wavelength of peak absorbance (λ max ) were related to the rod opsin sequences of individual sand gobies ( Pomatoschistus minutus ) from four allopatric populations [Adriatic Sea (A), English Channel (E), Swedish West Coast (S) and Baltic Sea (B)]. Rod λ max differed between populations in a manner correlated with differences in the spectral light transmission of the respective water bodies [λ max : (A)≈503 nm; (E and S)≈505–506 nm; (B)≈508 nm]. A distinguishing feature of B was the wide within-population variation of λ max (505.6–511.3 nm). The rod opsin gene was sequenced in marked individuals whose rod absorbance spectra had been accurately measured. Substitutions were identified using EMBL/GenBank X62405 English sand goby sequence as reference and interpreted using two related rod pigments, the spectrally similar one of the Adriatic P. marmoratus (λ max ≈507 nm) and the relatively red-shifted Baltic P. microps (λ max ≈515 nm) as outgroups. The opsin sequence of all E individuals was identical to that of the reference, whereas the S and B fish all had the substitution N151N/T or N151T. The B fish showed systematic within-population polymorphism, the sequence of individuals withλ max at 505.6–507.5 nm were identical to S, but those with λ max at 509–511.3 nm additionally had F261F/Y. The substitution F261Y is known to red-shift the rod pigment and was found in all P. microps . We propose that ambiguous selection pressures in the Baltic Sea and/or gene flow from the North Sea preserves polymorphism and is phenotypically evident as a wide variation in λ max .

Individual variation in rod absorbance spectra correlated with opsin gene polymorphism in sand goby (Pomatoschistus minutus)

Rod absorbance spectra, characterized by the wavelength of peak absorbance (lambda(max)) were related to the rod opsin sequences of individual sand gobies (Pomatoschistus minutus) from four allopatric populations [Adriatic Sea (A), English Channel (E), Swedish West Coast (S) and Baltic Sea (B)]. Rod lambda(max) differed between populations in a manner correlated with differences in the spectral light transmission of the respective water bodies [lambda(max): (A) approximately 503 nm; (E and S) approximately 505-506 nm; (B) approximately 508 nm]. A distinguishing feature of B was the wide within-population variation of lambda(max) (505.6-511.3 nm). The rod opsin gene was sequenced in marked individuals whose rod absorbance spectra had been accurately measured. Substitutions were identified using EMBL/GenBank X62405 English sand goby sequence as reference and interpreted using two related rod pigments, the spectrally similar one of the Adriatic P. marmoratus (lambda(max) approximately 507 nm) and the relatively red-shifted Baltic P. microps (lambda(max) approximately 515 nm) as outgroups. The opsin sequence of all E individuals was identical to that of the reference, whereas the S and B fish all had the substitution N151N/T or N151T. The B fish showed systematic within-population polymorphism, the sequence of individuals with lambda(max) at 505.6-507.5 nm were identical to S, but those with lambda(max) at 509-511.3 nm additionally had F261F/Y. The substitution F261Y is known to red-shift the rod pigment and was found in all P. microps. We propose that ambiguous selection pressures in the Baltic Sea and/or gene flow from the North Sea preserves polymorphism and is phenotypically evident as a wide variation in lambda(max).

Modified Thermal-Optical Analysis Using Spectral Absorption Selectivity To Distinguish Black Carbon from Pyrolized Organic Carbon

This study presents a method for analyzing the black carbon (BC) mass loading on a quartz fiber filter using a modified thermal-optical analysis method, wherein light transmitted through the sample is measured over a spectral region instead of at a single wavelength. Evolution of the spectral light transmission signal depends on the relative amounts of light-absorbing BC and char, the latter of which forms when organic carbon in the sample pyrolyzes during heating. Absorption selectivities of BC and char are found to be distinct and are used to apportion the amount of light attenuated by each component in the sample. Light attenuation is converted to mass concentration on the basis of derived mass attenuation efficiencies (MAEs) of BC and char. The fractions of attenuation due to each component are scaled by their individual MAE values and added together as the total mass of light absorbing carbon (LAC). An iterative algorithm is used to find the MAE values for both BC and char that provide the best fit to the carbon mass remaining on the filter (derived from direct measurements of thermally evolved CO2) at temperatures higher than 480 degrees C. This method was applied to measure the BC concentration in precipitation samples collected in northern California. The uncertainty in the measured BC concentration of samples that contained a high concentration of organics susceptible to char ranged from 12% to 100%, depending on the mass loading of BC on the filter. The lower detection limit for this method was approximately 0.35 microg of BC, and the uncertainty approached 20% for BC mass loading greater than 1.0 microg of BC.

Effect of the method of concentrating quartz feedstock on the optical characteristics of colored glass

The effect of the method of concentrating quartz feedstock on the purity of colored glass was investigated. It was shown that concentration of Kozlovskoe quartz sand by flotation and chemical methods allowed reducing the total FexOy by 3 times and obtaining glass with spectral light transmission in the visible region of up to 84%. The color tone of the experimental glasses made from initial and concentrated sand was within the yellow region according to calculations of the chromaticity coordinates and corresponding structures in the color triangle.

POSSIBILITIES OF INCREASING PRODUCTION AND QUALITY OF STRAWBERRY FRUITS AND SEVERAL FLOWERS BY NEW BLUE FLUORESCENT GREENHOUSE FILMS

Within the framework of the project SPECTRAFOIL funded by the EU and Grafe Color Batch (Germany), together with the industrial partners Palrig (Israel), Sunsaver (Spain) and several growers and research partners in Israel, Cyprus, Spain and The Netherlands, new fluorescent greenhouse films for several climates and several horticultural production systems were developed. One of the results of SPECTRAFOIL was the development of new blue fluorescent greenhouse films. Technical aspects were investigated, such as spectral light transmission, fluorescent effect, stability of pigments and films. The effect of different fluorescent films on the production and quality of strawberry fruits was investigated at A&F, Wageningen. In these experiments, strawberry plants were grown in small tunnels covered with films containing blue fluorescent pigments in different concentrations, which increased total light transmission and influenced light quality (more blue light) during the years 2002 and 2003. Both fruit production (number of fruits, fruit weight) and fruit quality (color, size, shape, dry matter, freedom from physiological disorders and diseases, balance between sugars and acids) were determined. Blue fluorescent films caused strawberry plants to produce a higher yield, a higher number of fruits and a slightly higher mean fruit size. Differences in fruit quality were small. Moreover, the effects of blue fluorescent films on different shrubs, perennials and annuals were tested at two growers in The Netherlands. Blue fluorescent films gave a 4 days earlier yield to Alchemilla and a 2 days earlier yield to Virburnum. Flower quality of Alchemilla was improved. This was probably due to higher day temperatures and lower humidity caused by a higher light transmission of the film. The same film caused a 5 days earlier yield to Celosia, at the same time improving flower quality. Blue fluorescent films have potentials to increase the yield of strawberry and force the flowering of perennials.

In vivo Light Scattering Intensity in the Lens versus in vitro Spectral Transmission in the Nuclear Region

In order to understand the correlation between nuclear opacity and spectral light transmission factor, the in vivo light scattering intensity of Scheimpflug lens images and the light transmission through slices of surgically removed nucleus were examined densitometrically as well as spectrophotometrically respectively, using both human and Brown Norway rat lenses. The experiments using rat lenses showed that the increase of the light scattering intensity in the nuclear regions is correlated with a decrease of the spectral transmission factor. The transparent anterior cortical region did not influence the light transmission (T%) through the nucleus. No significant influence was seen from the application of freezing and thawing procedures to measure light transmission. The examinations of the human subjects which were based on the rat study showed that the light transmission of nuclear cataracts objectively evaluated as grade I was almost the same as that observed in noncataractous nuclei. The light transmission of nuclear cataracts graded II or above, however, showed around 50% of the spectral light transmission of noncataractous nuclei.

Cut-off wavelength measurements of Ti:LiNbO3 channel waveguides

One of the most important parameters in characterization of integrated optical devices is precise determination of the effective cut-off wavelength of the fundamental and first-order modes, since this sets the exact region of single-mode operation. This paper describes an experimental set-up for determination of cut-off wavelengths of integrated optical waveguides, using the technique of spectral light transmission. Measurement results obtained with Ti:LiNbO3 channel waveguides are presented for straight waveguides, bent waveguides and polarizers.