The Economic Costs of Health Service Treatments for Asbestos-Related Mesothelioma Deaths

This article explores the complex and neglected picture of occupational and environmental disease healthcare costs specifically relating to asbestos. Diagnosed mesothelioma cases in Scotland in one calendar year were used to investigate the subject in greater depth. Data from UK sources on asbestos disease types recorded in 2000 and their disease treatment costs were obtained. Acute care economic costs of these diseases are estimated. One hundred and twenty diagnosed, recorded, and treated cases of asbestos-related diseases occurred in 2000 in Scotland. Mesothelioma accounted for 100 cases and directly cost Scottish National Health Service hospitals an estimated 942,038 pounds. The estimated UK figure in 2000 was at least 16,014,646 pounds because official figures for diagnosed and recorded deaths from mesothelioma are running at over 1700 a year with rises predicted for 2010 of 2000 deaths. By 2003, 50,000 people in the UK had died from diagnosed and recorded mesothelioma since records began. Earlier disease treatment costs would have been significantly lower than those in 2000 but, at 2000 prices, cost to the UK was roughly 471,019,000 pounds in acute hospital expenditure. Figures for primary care costs, including caregiver costs, are incomplete or unknown. These disease costs are substantial and have some international generalizability. Treatment patterns and costs vary greatly. Many lung cancer cases due to asbestos exposure occur globally for each mesothelioma case. Hence figures provided in this article are certain to be gross underestimates of the total health service and personal economic costs of asbestos illness and treatment in Scotland.

An investigation into the effect of thickness of titanium dioxide and gold-silver nanoparticle titanium dioxide composite thin-films on photocatalytic activity and photo-induced oxygen production in a sacrificial system

Thin films of titanium dioxide and titanium dioxide with incorporated gold and silver nanoparticles were deposited onto glass microscope slides, steel and titanium foil coupons by two sol-gel dip-coating methods. The film's photocatalytic activity and ability to evolve oxygen in a sacrificial solution were assessed. It was found that photocatalytic activity increased with film thickness (from 50 to 500 nm thick samples) for the photocatalytic degradation of methylene blue in solution and resazurin redox dye in an intelligent ink dye deposited on the surface. Contrastingly, an optimum film thickness of similar to 200 nm for both composite and pure films of titanium dioxide was found for water oxidation, using persulfate (S2O82-) as a sacrificial electron acceptor. The nanoparticle composite films showed significantly higher activity in oxygen evolution studies compared with plain TiO2 films.

Photocatalytic evolution of hydrogen and oxygen from ceramic wafers of commercial titanias

Several commercial titania photocatalyst powders were formed into thin (ca. 350 mu m), 25 mm diameter ceramic wafers, sputter deposited with Pt on one side. The activities of each of the ceramic wafers were tested for hydrogen and oxygen evolution from aqueous sacrificial systems. The commercial sample PC50 (Millennium Chemicals, UK) yielded reproducible ceramic wafers with high activity for water photoreduction. Many of the ceramic wafers displayed low water photo-oxidation activities; however, these were greatly increased with addition of a NiO co-catalyst. In a selected case, hydrogen evolution activity was compared between a PC50 wafer and an identical weight of platinised PC50 powder suspension. (C) 2010 Elsevier B.V. All rights reserved.

Adsorption and photocatalytic bleaching of acid orange 7 on P25 titania

The observed adsorption of acid orange 7, AO7(-), on P25 titania over a range of pH values (pH 2-8) gives a good fit to data generated using a charge distribution, multisite complexation, i.e. CD-MUSIC, model, modified for aggregated dye adsorption. For this system the model predicts that both the apparent dark Langmuir adsorption constant. K-L, and the number of adsorption sites, n(o), increase with decreasing pH, and are negligible above pH 6. At pH 2 the CD-MUSIC model predicts the fraction of singly co-ordinated sites occupied by the dye,f(AO7), is ca. 32% under the in situ monitoring experimental conditions used in this work to study the photocatalytic bleaching of AO7(-) under UV light illumination ([TiO2] = 20 mgdm(-3); [AO7(-)](total) = 4.86 x 10(-5) M). Although AO7(-) adsorption on P25 titania is insignificant above pH 6 and increases almost linearly and markedly below this pH, the measured initial rate of bleaching of AO7(-), photocatalysed by titania using UV appears to only increase modestly (

An Investigation into the Optimum Thickness of Titanium Dioxide Thin Films Synthesized by Using Atmospheric Pressure Chemical Vapour Deposition for Use in Photocatalytic Water Oxidation

Twenty eight films of titanium dioxide of varying thickness were synthesised by using atmospheric pressure chemical vapour deposition (CVD) of titanium(IV) chloride and ethyl acetate onto glass and titanium substrates. Fixed reaction conditions at a substrate temperature of 660 degrees C were used for all depositions, with varying deposition times of 5-60 seconds used to control the thickness of the samples. A sacrificial electron acceptor system composed of alkaline sodium persulfate was used to determine the rate at which these films could photo-oxidise water in the presence of 365 nm light. The results of this work showed that the optimum thickness for CVD films on titanium substrates for the purposes of water oxidation was approximate to 200 nm, and that a platinum coating on the reverse of such samples leads to a five-fold increase in the observed rate of water oxidation.

A comprehensive aerosol spray method for the rapid photocatalytic grid area analysis of semiconductor photocatalyst thin films

Indicator inks, previously shown to be capable of rapidly assessing photocatalytic activity via a novel photo-reductive mechanism, were simply applied via an aerosol spray onto commercially available pieces of Activ (TM) self-cleaning glass. Ink layers could be applied with high evenness of spread, with as little deviation as 5% upon UV-visible spectroscopic assessment of 25 equally distributed positions over a 10 cm x 10 cm glass cut. The inks were comprised of either a resazurin (Rz) or dichloroindophenol (DCIP) redox dye with a glycerol sacrificial electron donor in an aqueous hydroxyethyl cellulose (HEC) polymer media. The photo-reduction reaction under UVA light of a single spot was monitored by UV-vis spectroscopy and digital images attained from a flat-bed scanner in tandem for both inks. The photo-reduction of Rz ink underwent a two-step kinetic process, whereby the blue redox dye was initially reduced to a pink intermediate resorufin (Rf) and subsequently reduced to a bleached form of the dye. In contrast, a simple one-step kinetic process was observed for the reduction of the light blue redox dye DCIP to its bleached intermediates. Changes in red-green-blue colour extracted from digital images of the inks were inversely proportional to the changes seen at corresponding wavelengths via UV-visible absorption spectroscopy and wholly indicative of the reaction kinetics. The photocatalytic activity areas of cuts of Activ (TM) glass, 10 cm x 10 cm in size, were assessed using both Rz and DCIP indicator inks evenly sprayed over the films: firstly using UVA lamp light to activate the underlying Activ (TM) film (1.75 mW cm(-2)) and secondly under solar conditions (2.06 +/- 0.14 mW cm(-2)). The photo-reduction reactions were monitored solely by flat-bed digital scanning. Red-green-blue values of a generated 14 x 14 grid (196 positions) that covered the entire area of each film image were extracted using a Custom-built program entitled RGB Extractor(C). A homogenous degradation over the 196 positions analysed for both Rz (Red colour deviation = 19% UVA, 8% Solar: Green colour deviation = 17% UVA, 12% Solar) and DCIP (Red colour deviation = 22% UVA, 16% Solar) inks was seen in both UVA and solar experiments, demonstrating the consistency of the self-cleaning titania layer on Activ (TM). The method presented provides a good solution for the high-throughput photocatalytic screening of a number of homogenous photocatalytically active materials simultaneously or numerous positions on a single film; both useful in assessing the homogeneity of a film or determining the best combination of reaction components to produce the optimum performance photocatalytic film. (C) 2010 Elsevier B.V. All rights reserved.

Simple method for the rapid simultaneous screening of photocatalytic activity over multiple positions of self-cleaning films

An intelligent ink, previously shown to be capable of rapidly assessing photocatalytic activity, was simply applied via a felt-pen onto a commercially available piece of Activ (TM) self-cleaning glass. The ink, comprising of redox dye resazurin and the sacrificial electron donor glycerol within an aqueous hydroxy ethyl cellulose (HEC) polymer media, was photocatalytically degraded in a two-step process. The key initial stage was the photo-reductive conversion of resazurin to resorufin, whereby a colour change from blue to pink occurred. The latter stage was the subsequent photo-reduction of the resorufin, where a slower change from pink to colourless was seen. Red and green components of red-green-blue colour extracted from flat-bed scanner digital images of resazurin ink coated photocatalytic films at intervals during the photocatalysis reaction were inversely proportional to the changes seen via UV-visible absorption spectroscopy and indicative of reaction kinetics. A 3 x 3 grid of intelligent ink was drawn onto a piece of Activ (TM) and a glass blank. The photocatalysis reaction was monitored solely by flat-bed digital scanning. Red-green-blue values of respective positions on the grid were extracted using a custom-built program entitled RGB Extractor (c). The program was capable of extracting a number of 5 x 5 pixel averages of red-green-blue components simultaneously. Allocation of merely three coordinates allowed for the automatic generation of a grid, with scroll-bars controlling the number of positions to be extracted on the grid formed. No significant change in red and green components for any position on the glass blank was observed; however, the Activ (TM) film displayed a homogenous photo-reduction of the dye, reaching maxima in red and minima in green components in 23 +/- 3 and 14 +/- 2 min, respectively. A compositionally graded N-doped titania film synthesised in house via a combinatorial APCVD reaction was also photocatalytically tested by this method where 247 positions on a 13 x 19 grid were simultaneously analysed. The dramatic variation in photocatalysis observed was rapidly quantified for all positions (2-3 hours) allowing for correlations to be made between thicknesses and N : Ti% compositions attained from Swanepoel and WDX analysis, respectively. N incorporation within this system was found to be detrimental to film activity for the photocatalysis reaction of intelligent ink under 365 nm light.

A Novel, Fast-Responding, Indicator Ink for Thin Film Photocatalytic Surfaces

A new photocatalyst indicator ink based on methylene blue (MB) is described that allows the presence and activity of a thin (15 nm) photocatalytic film to be assessed in seconds. The ink is very stable (shelf life > 6 months) and the color change (blue to colorless) striking. The ink utilizes a sacrificial electron donor, glycerol, to trap the photogenerated holes, leaving the photogenerated electrons to react with MB to produce its. reduced, leuco, form (LMB). The efficacy of the MB ink is due to the presence of acid in its formulation, which curtails significantly. the otherwise usual, rapid reoxidation of LMB by ambient O-2.

A rapid method of assessing the photocatalytic activity of thin TiO2 films using an ink based on the redox dye 2,6-dichloroindophenol

An indicator ink based on the redox dye 2,6-dichloroindophenol ( DCIP) is described, which allows the rapid assessment of the activity of thin, commercial photocatalytic films, such as Activ. The ink works via a photoreductive mechanism, DCIP being reduced to dihydro-DCIP within ca. 7.5 minutes exposure to UVA irradiation of moderate intensity ( ca. 4.8mW cm(-2)). The kinetics of photoreduction are found to be independent of the level of dye present in the ink formulation, but are highly sensitive to the level of glycerol. This latter observation may be associated with a solvatochromic effect, whereby the microenvironment in which the dye finds itself and, as a consequence, its reactivity is altered significantly by small changes in the glycerol content. The kinetics of photoreduction also appear linearly dependent on the UVA light intensity with an observed quantum efficiency of ca. 1.8 x 10(-3). Copyright (C) 2008.

A comparative study of three techniques for determining photocatalytic activity

Quantitative measurement of the activity of photoactive films is an area of importance. The establishment of tests for standardisation of performance is important for efficient research but also a major milestone in achieving technology acceptance. In this paper, we compare three different techniques across a range of film samples from various sources. Furthermore, we demonstrate the potential of the dye-based approach as a quick and simple test. A series of photoactive film samples are compared for measured activity against each test. The test is shown to be capable of reproducible and quantitative activity results. The test has potential for use

Novel low-temperature photocatalytic titania films produced by plasma-assisted reactive dc magnetron sputtering

Robust, active, anatase titania films, 250 nm thick, are deposited onto glass at low temperatures, i.e., 2.0 for the photocatalytic mineralization of stearic acid. These films are typically 6.9 times more active than a sample of commercial self-cleaning glass, comprising a 15 nm layer of fitania deposited by CVD, mainly because they are much thicker and, therefore, absorb more of the incident UV light. The most active of the films tested comprised particles of P25, but lacked any significant physical robustness. Similar results, but much more quickly obtained, were generated using a photocatalyst- sensitive ink, based on the redox dye, resazurin, Rz. All fitania films tested, including those produced by magnetrom sputtering exhibited photo-induced superhydrophilicity. The possible future application of PAR-DG-MS for producing very active photocatalytic films on substrates not renowned for their high temperature stabilities, such as plastics, is noted. (c) 2006 Elsevier B.V All rights reserved.

Photocatalytic oxidation of deposited sulfur and gaseous sulfur dioxide by TiO2 films

Thick (4 mu m) films of anatase titania are used to photocatalyze the removal of deposited films of amorphous sulfur, similar to 2.8 mu m, thick and under moderate illumination conditions (I = 5.6 mW cm(-2)) on the open bench the process is complete within similar to 8 or 18 h using UVC or UVA light, respectively. Using UVA light, 96% of the product of the photocatalytic removal of the film of sulfur is sulfur dioxide, SO2. The photonic efficiency of this process is similar to 0.16%, which is much higher (> 15 times) than that of the removal of soot by the same films, under similar experimental conditions. In contrast to the open bench work, in a closed system the photocatalytic activity of a titania film toward the removal of sulfur decreased with repeated use, due to the accumulation of sulfuric acid on its surface generated by the subsequent photocatalytic oxidation of the initial product, SO2. The H2SO4-inactivated films are regenerated by soaking in water. The problems of using titania films to remove SO2 from a gaseous environment are discussed briefly.

Method of rapid assessment of photocatalytic activities of self-cleaning films

An ink, comprising the redox dye resazurin (Rz) and the sacrificial electron donor glycerol, is shown to be capable of the rapid assessment of the photocatalytic activities of self-cleaning films. In the key initial stage of photocatalysis the ink changes from blue to pink. Prolonged irradiation bleaches the ink and eventually mineralizes it. The kinetics of the initial photoinduced color change is studied as a function of UV irradiance, [glycerol], [Rz], and temperature. The results reveal an apparent approximate quantum yield of 3.5 x 10(-3) and an initial rate, r(i), which increases with [glycerol] and decreases with [Rz]. It is proposed that the reduction of Rz, dispersed throughout the thick (ca. 590 nm) indicator film, may take place either via the diffusion of the dye molecules in the ink film to the surface of the underlying semiconductor layer and their subsequent reaction with photogenerated electrons and/or via the diffusion of alpha-hydroxyalkyl radicals, produced by the oxidation of the glycerol by photogenerated holes, or hydroxy radicals, away from the surface of the semiconductor into the ink film and their subsequent reaction with the dye molecules therein. The decrease in r(i) with [Rz] appears to be due to dimer formation, with the latter impeding the reduction process. The activation energy for the initial color-change process is low, ca. 9.1 +/- 0.1 kJ mol(-1) and not unlike many other photocatalytic processes. The initial rate of dye reduction appears to be directly related to the rate of destruction of stearic acid. The ink can be applied by spin-coating, stamping, or writing, using a felt-tip pen. The efficacy of such an ink for assessing the photocatalytic activity of any photocatalytic film, including those employed on commercial self-cleaning glasses, tiles, and paving stones, is discussed briefly.

Simultaneous monitoring of the destruction of stearic acid and generation of carbon dioxide by self-cleaning semiconductor photocatalytic films

The destruction of stearic acid (SA), the SA test, is a popular approach used to evaluate the activities of photocatalytic films. The destruction of SA via semiconductor photocatalysis is monitored simultaneously, using FT-IR spectroscopy, via the disappearance of SA and the appearance of CO2, Sol-gel and P25 films of titania are used as the semiconductor photocatalytic self-cleaning films. A conversion factor is used of 9.7 x 1015 molecules of SA cm(-2) 1 Cru-1 integrated areas of the peaks in the Fr-IR of SA over the range 2700-3000 cm(-1), which is three times that reported previously by others. As the SA disappeared the concomitant amount of CO2 generated was > 90% that expected throughout the photomineralisation process for the sol-gel titania film. In contrast, the slightly more active, and scattering, P25 fitania films generated CO2 levels that dipped as low as 69% during the course of the photoreaction, but eventually recovered to congruent to 100% that expected based on the amount of SA present. The importance of these results with respect to SA test and the evaluation of new and existing self-cleaning films are discussed briefly. (c) 2006 Elsevier B.V. All rights reserved.