Measurement of solar ultraviolet radiation at a temperate and a tropical site using polysulphone film

Measurements of solar ultraviolet radiation (<320 nm) have been made with polysulphone film at a temperate and a tropical site and compared mean monthly values of the fraction of ultraviolet in solar radiation are calculated which allow an estimate of ultraviolet dose to be made from a knowledge of total solar radiation.While the data demonstrate the marked effect of sun elevation on the ultraviolet fraction of solar radiation they also indicate the effect of seasonal variation in the thickness of the ozone layer above the temperate site.It is also shown that whereas sunlight makes by far the major contribution to total solar radiation, skylight is of prime importance as regards ultraviolet radiation.     

Determination of ultraviolet radiation intensity using polysulphone film

The use of a polysulphone film as a physical standard for measuring light dosage in accelerated weathering tests is described. Tables are given of equivalent dose at 305 nm and correction factors for temperature of exposure. Examples of application are outlined showing effect of lamp and filter age on UV intensity and comparison of different light sources.     

Personal solar UV exposure measurements employing modified polysulphone with an extended dynamic range

Polysulphone dosimeters using a simple to use filter have been developed and tested to provide an extended dynamic measurement range of personal solar UV exposures over an extended period (3 to 6 days). At a Southern Hemisphere subtropical site (27.6 degrees S, 151.9 degrees E), the dynamic range of the filtered polysulphone allowed measurements of erythemal exposures to approximately 100 minimum erythemal dose (MED) for a change in optical absorbance at 330 nm (deltaA330) of 0.35. In comparison, unfiltered polysulphone dosimeters were exposed to approximately 8 MED for the same deltaA330. The error associated with the use of the filtered polysulphone dosimeters is of the order of +/-15%, compared with +/-10% of the unfiltered variety. The developed filtered polysulphone dosimeter system allowed the measurement of erythemal UV exposures over 3 to 6 days at a subtropical site without the need to replace the dosimeters because of saturation. The results show that longer-term measurement programs of personal solar UV have been made more feasible with the use of these polysulphone dosimeters with an extended dynamic range compared with unfiltered polysulphone dosimeters.     

Measurement and Analysis of Broadband UVB Solar Radiation in Spain

Measurements of broadband UVB irradiance (290–315 nm) at 14 locations in Spain for the period 2000–2009 have been used to generate instantaneous, hourly and daily values of irradiance (W m^?2) and radiant exposure (kJ m^?2). These measurements, and its statistical indices, have been analyzed. For the UVB irradiance, the values corresponding to July (maximum) and December (minimum) have been analyzed as representative of the year during the whole period for all locations. For the UVB radiant exposure, the temporal evolution of daily values has been evaluated for all locations to estimate an average yearly behavior. The accumulated radiant exposure for an average year has also been studied for each location. Finally, to determine possible trends in the evolution of the UVB levels, the linear regressions for the mean daily values for all locations have been determined.     

Enzyme-catalysed nitrate reduction-themes and variations as revealed by protein film voltammetry

Protein film voltammetry has been used to define the catalytic performance of two nitrate reductases: the respiratory nitrate reductase, NarGH, from Paracoccus pantotrophus and the assimilatory nitrate reductase, NarB, from Synechococcus sp. PCC 7942. NarGH and NarB present distinct "fingerprints" of catalytic activity when viewed in this way. Potentials that provide insufficient driving force for significant rates of nitrate reduction by NarB result in appreciable rates of nitrate reduction by NarGH. However, both enzymes display complex modulations in their rate of substrate reduction when viewed across the electrochemical potential domain.     

Anomalous lithium ion diffusion into CeO2·TiO2 thin film by film thickness variations

CeO₂·TiO₂ thin film is considered as an excellent candidate for a passive ion storage layer due to its good electrochemical stability and comparatively great charge capacitance. When cerium-titanium oxide thin film is adopted as an ion storage layer against cathodic tungsten oxide layer, the electrochromic device shows long term durability and cyclability. Therefore, many researchers investigated the composition and crystallinity effects to the charge density. In our study, we prepared CeO₂·TiO₂ thin by sol–gel dip-coating method, varying thickness by controlling withdrawal speeds. As investigating results of cyclic voltammetry and chronocoulometry, we found that there are three regions in the film thicknesses: (1) fast lithium ion diffusion region under 100 nm, (2) slow diffusion region in the range of 100 to 150 nm, and (3) fast and great charge capacitance region over 150 nm. In region 1, lithium ions diffuse very fast and reach into indium-tin oxide (ITO) layers, and slow diffusion region follows in region 2, probably due to the remains or impurities within the film, and in region 3, lithium ion diffusion gets fast again, accompanied with charge capacitance increase with thickness.     

The surface photo-degradation of bisphenol A polysulphone

ESCA has been used to monitor the changes in surface composition of polysulphone films irradiated in nitrogen and in low vacuum (λ > 290 nm). A photo-reduction of the sulphone group to a sulphide was observed. The extent of sulphide formation is dependent on both irradiation time and the partial pressure of oxygen. Comparison with results obtained from the irradiation of polyethylene and polycarbonate in sulphur dioxide atmospheres indicated that the photo-reduction is associated only with aromatic sulphones.     

Photoelectrochemical investigation of ultrathin film iron oxide solar cells prepared by atomic layer deposition

Atomic layer deposition was used to grow conformal thin films of hematite with controlled thickness on transparent conductive oxide substrates. The hematite films were incorporated as photoelectrodes in regenerative photoelectrochemical cells employing an aqueous [Fe(CN)(6)](3-/4-) electrolyte. Steady state current density versus applied potential measurements under monochromatic and simulated solar illumination were used to probe the photoelectrochemical properties of the hematite electrodes as a function of film thickness. Combining the photoelectrochemical results with careful optical measurements allowed us to determine an optimal thickness for a hematite electrode of ～20 nm. Mott-Schottky analysis of differential capacitance measurements indicated a depletion region of ～17 nm. Thus, only charge carriers generated in the depletion region were found to contribute to the photocurrent.     

Highly efficient dye-sensitized solar cells by TiCl4 surface modification of ZnO nano-flower thin film

Journal of Solid State Electrochemistry - In dye-sensitized solar cells (DSSCs), the semiconductor photo-anode film plays a significant role in enhancing the overall power conversion efficiency....     

Low-cost biodegradable lead sequestration film for perovskite solar cells

Despite the high efficiency that has been achieved for the perovskite solar cells(PSCs),the hazardous lead leakage from the perovskite absorber layer is one of the crucial barriers still hindering its penetration into the commercial market for a large-scale installation.Herein,we report a novel low-cost and biodegradable lead sequestration layer with high compatibility for up-scalable encapsulation of PSCs.Through a precisely designed cross-linking reaction of chemical agents,the as-made biodegr...     

Effect of cysteine on bovine serum albumin (BSA) denaturation induced by solar ultraviolet (UVA, UVB) irradiation.

Long-term exposure to natural sun-light (UVA, UVB) induced fluorescence and caused disulfide bond formation in bovine serum albumin (BSA). The addition of cysteine enhanced the bond formation to such an extent that a solution of BSA was transformed into an insoluble gel. The disulfide bonds in the gels are derived from internal-SH groups of protein. This reaction occurred even if cysteine was added after exposure to ultraviolet (UV)-irradiation. Fluorescent substances seem to be involved in this reaction. On the other hand, low concentrations of cysteine (less than 5 mM) inhibited both fluorescence and disulfide bond formation. The addition of glutathione to BSA produced the same effect as that of cysteine. The addition of thiourea to BSA solution inhibited fluorescence, but did not inhibit disulfide bond formation. We assume that external-SH compounds such as cysteine and glutathione, which have high reactivity with hydroxyl radicals (.OH), act not only as free-radical scavengers, but also as radical mediators in the polymerization of protein through disulfide cross-links induced by UV-irradiation. Solar UVA as well as UVB irradiation are shown to have the same effect on the protein polymerization.     

Spectral monitoring of biologically active solar UVB radiation using an in vitro model of vitamin D synthesis

Vitamin D synthetic capacity of sunlight is the most well known beneficial effect of solar UV radiation. The article describes the new method of biological dosimetry of solar (and artificial) UV radiation based on an in vitro model of vitamin D synthesis (D-dosimeter). Particular attention is given to spectrophotometric analysis of the multicomponent mixture of vitamin D photoisomers that has been developed for the most effective use of D-dosimeter in situ.     

Applicability of the polysulphone horizontal calibration to differently inclined dosimeters

Polysulphone (PS) dosimetry has been a widely used technique for more than 30 years to quantify the erythemally effective UV dose received by anatomic sites (personal exposure). The calibration of PS dosimeters is an important issue as their spectral response is different from the erythemal action spectrum. It is performed exposing a set of PS dosimeters on a horizontal plane and measuring the UV doses received by dosimeters using calibrated spectroradiometers or radiometers. In this study, data collected during PS field campaigns (from 2004 to 2006), using horizontal and differently inclined dosimeters, were analyzed to provide some considerations on the transfer of the horizontal calibration to differently inclined dosimeters, as anatomic sites usually are. The role of sky conditions, of the angle of incidence between the sun and the normal to the slope, and of the type of surrounding surface on the calibration were investigated. It was concluded that PS horizontal calibrations apply to differently inclined dosimeters for incidence angles up to approximately 70° and for surfaces excluding ones with high albedo. Caution should be used in the application of horizontal calibrations for cases of high-incidence angle and/or high albedo surfaces.     

Dye-sensitized solid-state solar cells fabricated by screen-printed TiO_2 thin film with addition of polystyrene balls

The screen-printed nanoporous TiO2 thin film was employed to fabricate dye-sensitized solid-state solar cells using CuI as hole-transport materials. The solar cell based on nanoporous TiO2 thin film with large pores formed by the addition of polystyrene balls with diameter of 200 nm to the TiO2 paste exhibits photovoltaic performance enhancement, which is attributed to the good contact of CuI with surface of dye-sensitized thin film due to easy penetration of CuI in the film with large pores.     

Positronium annihilation studies of polycarbonate,polyethersulphone and polysulphone

Positron annihilation studies are reported on polycarbonate polyethersulphone and polysulphone over the temperature range 260–370 K. The data were analysed into three components, the longest lifetime-o-component is associated with the pick-off mechanism; a linear variation of that component with temperature was observed. Using ultrasonic velocity data, the free volume distribution was calculated; its magnitude and temperature dependence are discussed in relation to the mechanical properties of the polymer.     

Measurement of anisotropic refractive indices of free-standing polymer film

A new technique has been developed to measure the optical refractive indices in the parallel and perpendicular directions to the film surfaces and applied to measure the refractive indices of free-standing polymer films. The refractive indices were obtained by measuring the reflectivity as a function of the incident angle. The angle dependence of the reflectivity which results from the interference of the light beam reflected from the front and rear interfaces of the film was analysed by means of the Fresnel equation. This technique can be used to measure the refractive indices in three major axes, i.e. one out-of plane axis and two in-plane axes of the sample. This technique gives values for the refractive indices and the thickness simultaneously with an accuracy comparable to that measured by optical wave-guide technique. The validity of the technique has been tested with polymer films of known refractive indices such as poly(methyl methacrylate) and polyimide (PMDA-ODA).