Tear film lipid layer - from composition to function : implications of the anti-evaporative effect

The tear film lining the ocular surface consists of three qualitatively different layers. The hydrated (i) mucous matrix, which is composed of the epithelial glycocalyx and secreted gel-like mucins, continues as a concentration gradient into the overlaying protein-rich (ii) aqueous layer, which is largely responsible for the hydration, nutrition, and host defence of the ocular surface. Finally, the air-tear interface is lined with a thin (iii) tear film lipid layer (TFLL), which is considered to stabilise the entire tear film and is thought to retard evaporation from the air-tear interface. Meibum, an oily secretion produced by meibomian glands, is considered largely as the source of the TFLL lipids. The integrity of the tear film is vital for the ocular surface, and disturbances in any of the aforementioned sections typically result in dry eye symptoms. Despite the extremely low evaporation rates measured from the ocular surface in vivo, no evaporation-retarding mechanism of TFLL has been shown in vitro. Altogether, due to the co-operative character of lipids, the function and behaviour of the TFLL and similar lipid layers are largely defined by their lipid composition. To understand the behaviour of complex lipid layers on the molecular level, the composition of the layer should be determined. Therefore, the first aim of this study was to analyse the lipid composition of tear fluid. Because most of the lipids are considered to be located in the TFLL, the aim was to create TFLL-like lipid compositions for in vitro experiments. Finally, the aim was to investigate the evaporation-retarding effect of such lipid layers to better understand the potential mechanism of evaporation retardant in vivo TFLL. A modern mass-spectrometric platform, namely ultra performance liquid chromatography coupled to quadrupole time-of-flight mass spectrometry, was employed for the tear fluid lipid analysis. In contrast to the widely recognised meibum lipid composition, the tear fluid samples contained a considerable amount of phospholipids. Unfortunately, most of the non-polar lipids, such as the cholesteryl esters and the wax esters typically present in meibum, could not be detected using this mass spectrometric platform; however, they were detected with enzymatic assays and thin layer chromatography. In addition, we demonstrated that the phospholipids function as a spreading aid facilitating the uniform spreading of the hydrophobic non-polar lipids at the air-water interface. Based on the tear fluid lipid composition, we created TFLL-like lipid compositions and investigated their ability to retard evaporation from the air-water interface in vitro. A custom-built system was assembled for evaporation rate determination, and Brewster angle microscopy was employed to observe the interfacial organisation of the lipid layer at the air-water interface. It was found that very specific lipids and very definite lipid compositions are needed to retard evaporation from the air-water interface. None of the complex TFLL-like lipid compositions retarded evaporation. However, a specific class of TFLL lipids, namely wax esters (WEs), were shown to be efficient evaporation retardants, but layers composed of WEs mixed with large proportions of other TFLL lipids did not retard evaporation. WEs, however, did not retard evaporation under all conditions, but only in a defined phase of the layer. This phase and therefore the evaporation-retarding effect was dependent on the melting point of the specific WE and the temperature of the air-water interface. The WEs that were close to their bulk melting temperature retarded evaporation, whereas the WEs in their solid or liquid states lacked this property. In their solid state, the WEs did not spread as a uniform layer at the air-water interface, whereas in their liquid state, the WEs formed very fluid layers, and therefore, the water molecules diffused through the loosely packed lipid layer. We also investigated the surface-active properties of WEs and noted that WEs are expectedly poor surfactants compared to phospholipids; they are extremely prone to aggregation and are poorly compressible, especially when the layer is in the evaporation-retarding phase. These results support the theory suggested in our lipid composition study: hydrophobic lipids need to be mixed with a certain amount of amphiphilic lipids to form rapidly spreading films at the air-water interface. In summary, this thesis project concentrated on providing an in vitro model for linking certain functions, properties, and behaviours of TFLL to the composition of such layers. In short, amphiphilic phospholipids seem to be a vital component of the TFLL, although possibly in a smaller proportion than originally hypothesised, providing aid for non-polar lipid spreading. The evaporation-retarding effect is largely dependent on the composition. Pure WEs turned out to be effective evaporation-retarding TFLL lipids, but only in a certain temperature-dependent phase. Therefore, WEs are most likely the lipids that provide the evaporation-retarding effect of the TFLL; however, such complex evaporation-retarding lipid composition is yet to be determined in vitro. The results of this thesis suggest that the compositional changes affect the behaviour, such as spreading and the evaporation-retarding effect, of TFLL. Defects in such properties may result in accelerated evaporation from the ocular surface and, consequently, in dry eye symptoms.Kyynelneste muodostaa silmän pinnalle vain mikrometrien paksuisen kalvon. Sen päätehtäviä on kosteuttaa ja ravita silmän pintaa sekä suojata silmää fyysisesti ja biokemiallisesti. Yhtenäinen kalvo takaa myös valon esteettömän pääsyn silmään. Kyynelnestekalvon pinnalla olevan vain kymmenien nanometrien paksuisen rasva- eli lipidikalvon rakenne ja toiminta tunnetaan yhä huonosti. Nykykäsityksen mukaan lipidikalvo alentaa kyynelnestekalvon pintajännitystä ja hidastaa ohuille nestekalvoille tyypillistä repeämistä. Kyynelnestekalvolta mitattujen haihtumisnopeuksien perusteella sen on ajateltu myös hidastavan kyynelnesteen haihtumista silmän pinnalta. Kuivan silmän syndrooma on yksi tyypillisimmistä syistä hakeutua silmälääkärin vastaanotolle. Oireita ovat ärsytys, vetistys, hiekantunne ja polttava tai pistävä tunne silmän pinnalla. Vaikeimmissa tapauksissa potilaat ovat alttiita silmien tulehduksille, haavaumille ja pysyvälle arpeutumiselle. Kuiva silmä voi aiheutua monesta syystä; yksi mahdollisista syistä on lipidikalvon alentunut kyky hidastaa haihtumista. Tämä johtuu mahdollisesti lipidikalvon muodostavien rasva-aineiden normaalista poikkeavasta erityksestä silmäluomien alapinnalla sijaitsevissa Meibomin rauhasissa. Lipidikalvon ominaisuuksien laajempi tuntemus voi auttaa paremmin ymmärtämään kuivasilmäisyyden syitä ja voi siten mahdollistaa uusien hoitomuotojen kehittämisen. Tässä tutkimuksessa perehdyttiin kyynelnestekalvon rasvakoostumukseen tutkimalla silmän pinnalta kerättyjä kyynelnestenäytteitä ensisijaisesti nestekromatografia massaspektrometrisesti. Koostumuksen perusteella saatiin selville, että lipidikalvo sisältää merkittävän osan fosfolipidejä jo aiemmin löydettyjen kolesteryyliesterien, vahaesterien ja triglyseridien lisäksi. Tutkimuksemme perusteella fosfolipidit ovat todennäköisesti ratkaiseva rasva-aine tasaisesti levittäytyvän ja siten toimivan lipidikalvon muodostumisessa. Rasvakoostumuksen perusteella tutkittiin laboratoriotekniikoin kyynelnesteen lipidikalvoa muistuttavien kalvojen kykyä estää haihtumista veden pinnalta. Kyseiset useasta rasvasta muodostuneet kalvot eivät yllättäen estäneet haihtumista merkittävästi. Toisaalta erään kyynelnesteessä esiintyvän yksittäisen rasva-aineen, vahaesterien, todettiin hidastavan haihtumista jopa yli 50%, mutta vain silloin kuin yli 90% lipidikalvosta muodostui vahaesteristä. Lisäksi vahaesterien haihtumisenestokyky oli jyrkästi riippuvainen lämpötilasta: vahaesterikalvot hidastivat haihtumista vain silloin kun lämpötila oli lähellä niiden sulamispistettä. Yhteenvetona voidaan päätellä, että fosfolipideillä on merkittävä vaikutus tasaisesti leviävän lipidikalvon muodostumiseen ja, että lipidikalvon haihtumisenestokyky on erittäin riippuvainen sen rasvakoostumuksesta. Vahaesterit ovat todennäköisesti merkittävin haihtumisenestokykyyn vaikuttava rasva-aine kyynelnesteen lipidikalvossa. Muiden rasva-aineiden osallisuus haihtumisen estämisessä on vielä epäselvä ja vaatii siten lisätutkimusta. Kyynelnesteen lipidikalvon oikeanlainen toiminta on erittäin riippuvainen sen koostumuksesta ja häiriöt kalvon rakenteessa saattavat johtaa kyynelnesteen liialliseen haihtumiseen ja mahdollisesti kuivan silmän oireisiin

Scaling the Power and Tailoring the Wavelength of Semiconductor Disk Lasers

Optically pumped semiconductor disk lasers (SDLs) provide a unique combination of high output power, high beam quality and possible emission wavelengths spanning from the ultraviolet to the mid-infrared spectral range. In essence, SDLs combine the wavelength versatility of semiconductor gain media with the power scaling principles of optically pumped solid state disk lasers. The emission wavelength of SDLs can be tailored to match the desired application simply by altering the composition of the gain material. High power operation, however, requires efficient thermal management, which can be realized using thin structures that are integrated with industrial diamond heat spreaders. The main objective of this thesis was to develop methods for increasing the output power of optically pumped SDLs, especially in challenging wavelength regions. The work included integrating SDL gain elements onto diamond heat spreaders using thin intermediate gold layers. This configuration enabled 45–50 % higher output powers than conventional bonding with indium solder. In addition, the reflectivity of the SDL gain mirror was enhanced using a semiconductor-dielectric-metal compound mirror. This procedure enabled 30 % thinner mirror structures when compared with the conventional design, where the reflectivity of the semiconductor mirror is enhanced with a metal layer. Finally, thin GaAs-based semiconductor mirrors were integrated with InP-based active regions. Such integration is necessary for high power operation in the spectral range 1.3–1.6 µm, because InP-based compounds for a highly reflective thin mirror section are not available. The configuration enabled record-high output powers of 6.6 W and 4.6 W at the wavelengths of 1.3 µm and 1.58 µm, respectively. The second objective of this thesis was to generate high output powers in single-frequency operation and via intracavity frequency-doubling. In single-frequency operation, record-high output powers of 4.6 W and 1 W were demonstrated at the wavelengths of 1.05 µm and 1.56 µm, respectively. Such light sources are required for numerous applications including free-space communications and high resolution spectroscopy. In addition, second-harmonic generation was demonstrated with SDLs emitting at 1.3 µm and 1.57 µm. The output powers reached 3 W at 650 nm and 1 W at 785 nm, which represent record-high output powers from SDLs in this wavelength range. These types of lasers could be especially useful in biophotonics and medical applications

The Effect of Phospholipids on Tear Film Lipid Layer Surface Activity

Peer reviewe

Human Tear Fluid Lipidome: From Composition to Function

We have explored human aqueous tear fluid lipidome with an emphasis to identify the major lipids. We also address the physiological significance of the lipidome. The tears were analysed using thin layer chromatographic, enzymatic and mass spectrometric techniques. To emphasize the physiological aspect of the lipidome, we modelled the spreading of the non-polar tear fluid lipids at air-water interface in macroscopic scale with olive oil and egg yolk phosphatidylcholine. Based on enzymatic analysis the respective concentrations of choline-containing lipids, triglycerides, and cholesteryl esters were 48±14, 10±0, and 21±18 µM. Ultra performance liquid chromatography quadrupole time of flight mass spectrometry analysis showed that phosphatidylcholine and phosphatidylethanolamine were the two most common polar lipids comprising 88±6% of all identified lipids. Triglycerides were the only non-polar lipids detected in mass spectrometric analysis i.e. no cholesteryl or wax esters were identified. The spreading experiments show that the presence of polar lipids is an absolute necessity for a proper spreading of non-polar tear fluid lipids. We provide evidence that polar lipids are the most common lipid species. Furthermore, we provide a physiological rationale for the observed lipid composition. The results open insights into the functional role of lipids in the tear fluid and also aids in providing new means to understand and treat diseases of the ocular surface.Peer reviewe

Maaseudun rakennemuutoksessa mahdollisuuksia

Maatalouden toimintaympäristö muuttuu koko ajan. Maatalouden rakennemuutosten ja tukipolitiikanuudistusten vuoksi maatilojen määrän ennustetaan vähenevän voimakkaasti. Lisäksi toiminta keskittyyja tilakoko kasvaa Lapin läänin alueella.Yrittäjän ikä, tilan kannattavuuden lasku sekä tuotantovälineiden uusimisen tarve vaikuttavatyrittäjän mahdollisuuksiin tai halukkuuteen jatkaa maatilan toimintaa tai etsiä uusia tuotantovaihtoehtoja.Maataloudesta luopuvilla tiloilla on yleensä paljon sekä fyysisiä että henkisiä resursseja harjoittaauutta elinkeinotoimintaa. Tulevaisuuden ennakointiin ja eri tekijöiden yhteisvaikutusten arviointiin japäätöksentekoon yrittäjä kaipaa usein asiantuntijoiden tukea.Multimaaseutu hanke tukee maatiloja ja maaseutuyrityksiä selvittämällä tulevaisuuden toimintavaihtoehtojaja antamalla neuvoja uuden toiminnan käynnistämisessä. Neuvonnan ja tutkimuksen parissatyöskentelevät asiantuntijat muodostivat hankkeessa tiimejä, joissa tutkimustieto ja käytännönosaaminen palvelivat yritystoiminnan kehittämistä. Samalla luotiin yhteistyömallia, joissa asiantuntijajatutkimusorganisaatiot kytkettiin entistä tiiviimmin uusien toimialojen ja yritystoiminnan kehittämiseen.Tällaisessa tiimityöskentelymallissa voidaan tutkimustakin suunnata uusiin haasteisiin ja parantaasen vaikuttavuutta. Neuvonnan ja tutkimuksen räätälöimä toimintasuunnitelma on hyvä startti uuteenyrittäjyyteen.Hankkeen aikana on selvinnyt, että on tarkoituksenmukaista tehdä toimialaselvityksiä, jotka tukevathankkeen toteuttamista tuottamalla informaatiota ja antamalla välineitä kehittämistyöhön. Peltojabioenergiaselvityksen tavoitteena oli tutkia Lapissa menestyvien peltokasvien soveltuminen biokaasutuotannonraaka-aineeksi sekä biomassan että laadun osalta. Peltoenergiatutkimuksessa erilaistenkasvien tuottokykyä verrattiin ruokohelpeen. Lisäksi selvitettiin laajemmin bioenergian käyttömahdollisuuksia.Maaseutumatkailu on kehittyvä toimiala Lapissa. Matkailu liittyy lähes kahteen kolmasosaankäynnistyvistä yrityshankkeista. Selvityksen tavoitteena oli laatia toimintamalleja matkailupalveluidentuotantoon sekä osoittaa kannattavuuden edellytykset ja menestystekijät. Lisäksi selvitettiinemolehmätuotannon ja lihan jatkojalostuksen reunaehtoja ja toteuttamis- ja kannattavuusedellytyksiäkoko tuotantoketjussa. Toimialaselvitysten hyöty kohdistuu ensisijaisesti hankeyritysten kehittämiseen,mutta tieto on jatkossa hyödynnettävissä myös muiden maaseutuyritysten toiminnan kehittämisessä

Immobilization of natural lipid biomembranes and their interactions with choline carboxylates : A Nanoplasmonic sensing study

The cell membrane is mainly composed of lipid bilayers with inserted proteins and carbohydrates. Lipid bilayers made of purified or synthetic lipids are widely used for estimating the effect of target compounds on cell membranes. However, the composition of such biomimetic membranes is much simpler than the composition of biological membranes. Interactions between compounds and simple composition biomimetic membranes might not demonstrate the effect of target compounds as precisely as membranes with compositions close to real organisms. Therefore, the aim of our study is to construct biomimetic membrane closely mimicking the state of natural membranes. Liposomes were prepared from lipids extracted from L-alpha-phosphatidylcholine, Escherichia coli, yeast (Saccharomyces cerevisiae) and bovine liver cells through agitation and sonication. They were immobilized onto silicon dioxide (SiO2) sensor surfaces using N-(2-hydroxyethyl)piperazine-N'-2-ethanesulfonic acid buffer with calcium chloride. The biomimetic membranes were successfully immobilized onto the SiO2 sensor surface and detected by nanoplasmonic sensing. The immobilized membranes were exposed to choline carboxylates. The membrane disruption effect was, as expected, more pronounced with increasing carbohydrate chain length of the carboxylates. The results correlated with the toxicity values determined using Vibrio fischeri bacteria. The yeast extracted lipid membranes had the strongest response to introduction of choline laurate while the bovine liver lipid extracted liposomes were the most sensitive towards the shorter choline carboxylates. This implies that the composition of the cell membrane plays a crucial role upon interaction with choline carboxylates, and underlines the necessity of testing membrane systems of different origin to obtain an overall image of such interactions.Peer reviewe

Impact of Surface-Active Guanidinium-, Tetramethylguanidinium-, and Cholinium-Based Ionic Liquids on Vibrio Fischeri Cells and Dipalmitoylphosphatidylcholine Liposomes

We investigated the toxicological effect of seven novel cholinium, guanidinium, and tetramethylguanidinium carboxylate ionic liquids (ILs) from an ecotoxicological point of view. The emphasis was on the potential structure-toxicity dependency of these surface-active ILs in aqueous environment. The median effective concentrations (EC50) were defined for each IL using Vibrio (Aliivibrio) fischeri marine bacteria. Dipalmitoylphosphatidylcholine (DPPC) liposomes were used as biomimetic lipid membranes to study the interactions between the surface-active ILs and the liposomes. The interactions were investigated by following the change in the DPPC phase transition behaviour using differential scanning calorimetry (DSC). Critical micelle concentrations for the ILs were determined to clarify the analysis of the toxicity and the interaction results. Increasing anion alkyl chain length increased the toxicity, whereas branching of the chain decreased the toxicity of the ILs. The toxicity of the ILs in this study was mainly determined by the surface-active anions, while cations induced a minor impact on the toxicity. In the DSC experiments the same trend was observed for all the studied anions, whereas the cations seemed to induce more variable impact on the phase transition behaviour. Toxicity measurements combined with liposome interaction studies can provide a valuable tool for assessing the mechanism of toxicity.Peer reviewe

Interactions of Ionic Liquids and Spirocyclic Compounds with Liposome Model Membranes. A Steady-State Fluorescence Anisotropy Study

Understanding the toxicity of ionic liquids (ILs) is crucial in the search of greener chemicals. By comparing in vivo toxicity and in vitro interactions determined between compounds and biomimetic lipid membranes, more detailed toxicity vs. structure relation can be obtained. However, determining the interactions between non-surface-active compounds and liposomes has been a challenging task. Organisational changes induced by ILs and IL-like spirocyclic compounds within 1,6-diphenyl-1,3,5-hexatriene-doped biomimetic liposomes was studied by steady-state fluorescence anisotropy technique. The extent of organisational changes detected within the liposome bilayers were compared to the toxicity of the compounds determined using Vibrio Fischeri bacteria. Four liposome compositions made of pure 1-palmitoyl-2-oleyl-sn-glycero-3-phosphocoline (POPC) and mixtures of POPC, 1-palmitoyl-2-oleyl-sn-glycero-3-phosphoserine (POPS), and cholesterol (Chol) were tested as biomimetic models. Changes observed within the POPC/POPS/Chol 55:20:25 bilayers correlated the best with the toxicity results: ten out of twelve compounds followed the trend of increasing bilayer disorder - increasing toxicity. The study suggests that the toxicity of non-surface-active compounds is dependent on their ability to diffuse into the bilayers. The extent of bilayer's organisational changes correlates rather well with the toxicity of the compounds. Highly sensitive technique, such as fluorescence anisotropy measurements, is needed for detecting subtle changes within the bilayer structures.Peer reviewe

Vapor-Liquid Equilibrium of Ionic Liquid 7-Methyl-1,5,7-triazabicyclo[4.4.0]dec-5-enium Acetate and Its Mixtures with Water

Ionic liquids have the potential to be used for extracting valuable chemicals from raw materials. These processes often involve water, and after extraction, the water or other chemicals must be removed from the ionic liquid, so it can be reused. To help in designing such processes, we present data on the vapor-liquid equilibrium of the system containing protic ionic liquid 7-methyl-1,5,7-triazabicyclo [ 4.4.0 ] dec-5-enium acetate, water, acetic acid, and 7-methyl-1,5,7-triazabicyclo [4.4.0] dec-5-ene. Earlier studies have only focused on mixtures of water and an ionic liquid with a stoichiometric ratio of the ions. Here, we also investigated mixtures containing an excess of the acid or base component because in real systems with protic ionic liquids, the amount of acid and base in the mixture can vary. We modeled the data using both the ePC-SAFT and NRTL models, and we compared the performance of different modeling strategies. We also experimentally determined the vapor composition for a few of the samples, but none of the modeling strategies tested could accurately predict the concentration of the acid and base components in the vapor phase.Peer reviewe

Potential consequences of hypothetical nuclear power plant accidents in Finland

An assessment of the environmental consequences of radioactive releases from severe reactor accidents was performed for Finnish nuclear power plants (NPP) in operation (Loviisa 1 and 2, and Olkiluoto 1 and 2), in commissioning (Olkiluoto 3) and in the preparatory phase (Hanhikivi 1). Three hypothetical radioactive releases (Basic, Large and Very Large cases) with different magnitudes were considered. Basic case represents a release corresponding to the limit set in requirements for severe reactor accidents, and thus, the other two represent extremely unlikely situations where severe accident management has failed. The magnitude of Very Large case is similar to the Fukushima NPP accident and roughly one order of magnitude smaller than the Chernobyl NPP accident, while the magnitude of Large case is roughly one order of magnitude smaller. The environmental assessment on the consequences of the releases was performed using a probabilistic approach. The aim is to estimate radiation doses to the population around the NPP and land contamination resulting from the release of radioactive material. The results of the assessment were compared to the protective action criteria for radioactive release from an NPP, and further used to evaluate the sufficiency of the Precautionary Action Zone (PAZ) and Emergency Planning Zone (EPZ) given in Finnish regulation. The probability of exceeding different operational intervention levels (OIL) and dose criteria set for external dose rate, effective dose, thyroid dose, deposition of strong gamma emitters, deposition of cesium, and concentration of gamma emitters in the air were estimated for distances up to 300 km from each site. Dispersion and deposition of releases were modelled with the dispersion model SILAM of the Finnish Meteorological Institute. The modelling applied historical weather forecast data from the years 2012–2015 retrieved with operative weather forecast models AROME and HARMONIE. Dose rates and doses were determined from the radionuclide air concentrations and depositions with the threat assessment tool TIUKU. The assessment was preformed using 2920 dispersion realizations for each reactor type and release scenario. For the assessment, the 95th percentile of the modelled dispersion, deposition and dose data was selected. The assessment showed that it is unlikely that any OILs or dose criteria would be exceeded outside PAZ and EPZ in a Basic case. In a Large case, the OILs may be exceeded up to about 110 km from the NPP sites, while it could be up to 170 km for dose criteria for the recommendation to limit being outside and iodine prophylaxis for children and pregnant females. The assessment indicated that it is unlikely that sheltering indoors or evacuation are needed outside the PAZ and EPZ during the early phase of the emergency due to the release in a Large case. In a Very Large case, extensive protective actions including permanent or temporary relocation are needed outside EPZ and less restrictive protective actions (i.e., recommendation to limit being outside and iodine prophylaxis for children and pregnant females) are needed beyond the area considered in this study (> 300 km). It was shown, however, that the protective actions outside the PAZ and EPZ are strongly dependent on prevailing weather conditions. It was observed that the dose criteria for an adult’s effective and thyroid dose were exceeded in larger areas than suggested by the criteria based on the external dose rate. Furthermore, dose criteria for a child’s thyroid dose were exceeded in larger areas than the dose criteria for the recommendation to limit being outside, even though the iodine prophylaxis for children and pregnant females is set as a complementary protective action for the recommendation to limit being outside. The observation demonstrates that the content of the radioactive release must be carefully considered in a severe NPP accident as the amount of released iodine isotopes affect the thyroid dose, while other nuclides make only a small contribution to it. It was also observed that precipitation may cause the deposition of radioactive substances such that in large areas the criteria for protective action based on deposition may be exceeded, even when protective actions would not be warranted according to dose criteria for effective doses. In Large and Very Large cases, the deposition may lead to the need for decontamination of large areas, and temporary or even permanent relocation of people. These findings demonstrate the importance of primarily using dose criteria in decision making if dose calculations can be performed reliably during the actual nuclear or radiological emergency. The OILs shall be used only if measures with dose criteria cannot be determined reliably e.g., due to a lack of information. Based on the results, it was concluded that further study is needed to set an Extended Planning Distance (EPD) and Ingestion and Commodities Planning Distance (ICPD). In such a study, a level 2 Probabilistic Risk Assessments (PRA) considering the probability of atmospheric releases should be better linked with environmental consequence assessment. The International Atomic Energy Agency (IAEA) recommends the EPD and ICPD to facilitate preparedness planning and the execution of protective actions beyond the PAZ and EPZ. The existence of an EPD and ICPD could also improve the effective co-operation of different authorities and emergency workers in a nuclear emergency. In Large and Very Large cases, the seasonal variations between summer and winter were found to be significant especially when considering deposition of cesium and strong gamma emitters. It was observed that precipitation during the winter season causes more wet deposition than in the summer. In a Very Large case, the seasonal variations were also significant in other measures