Composition depth profiling of polystyrene/poly(vinyl ethyl ether) blend thin films by angle resolved XPS

Angle resolved XPS (ARXPS) and scanning force microscopy (SFM) are used to study polystyrene/poly(vinyl ethyl ether) 50/50 wt% blend thin films spin cast from toluene solution, as a function of polystyrene molecular weight and film thickness. ARXPS is used to investigate the composition depth profile (CDP) of the blend thin films and SFM to study their surface morphology and miscibility. The CDPs are modelled by an empirical hyperbolic tangent function with three floating parameters. These are determined by non-linear least squares regression, their uncertainties estimated and the curve fit residuals analysed to demonstrate that the hyperbolic tangent CDP is a satisfactory fit to the ARXPS data. Conclusions are drawn regarding the behaviour of the blend thin films as the thickness and polystyrene molecular weight are varied. Flory-Huggins interaction parameters (chi) for the mixtures are calculated based upon the segregation data, and suggest a value of chi = 0.05 to be appropriate for this system. (c) 2009 Elsevier B.V. All rights reserved

An investigation on the feeding behavior of common kilka (Clupeonella cultriventris caspia) in the southern Caspian Sea, Mazandaran Province, Iran

Monthly samples of common kilka (Clupeonella cultriventris caspia) were collected at night on board of kilka fishing vessel during the years 2004-2005 in Mazandran province. The decreasing kilka population in the Caspian Sea and the associated economic loss of fisheries sector were the main reasons encouraging the research. The stomach contents of common kilka and biotic and abiotic factors at the fishing areas were examined in this project. The length and weight of common kilka fluctuated between 100 ±7 to 113 ±5 mm and 7.0 ±1.9 to10.3 ±1.0g, respectively. The highest feeding activity was observed in April with 280 plus or minus 153 individuals of prey weighing 2.9 plus or minus 1.6mg per fish consisted of 7% Acartia and 93% Balanus nauplii and cipris. The zooplankton population taken in during March to September was composed of Balanus nauplii and cipris (67% to 100%) but the biomass of copepoda (Acartia) was dominant from October to February. We observed that with increasing temperature in spring, Balanus reproduced and the stomach contents of kilka comprised more than 90% Balanus cipris and nauplii. In winter, Copepoda was observed more in stomach contents of kilka while Balanus decreased

Distribution of zooplankton in the southern Caspian Sea

The zooplanktons were studied in spring, autumn and winter in the southern Caspian Sea in 1996. Sampling carried out in four season. In each season, 180 specimens were identified and their frequency calculated per m^3. 55 species of zooplanktons were identified including 55% Cladocera, 15% Copepoda and 11 % Rotatoria, 9% other groups such as meroplanktons. The maximum species diversity was observed for Cladocera and the maximum frequency were observed for Copepoda. The Copepoda affected on abundance of zooplanktons as this frequency included in spring, summer, autumn and winter that were 38% to 97%, 22% to 92%, 71 % to 99% and 31 % to 92%, respectively. In summer, the Copepoda and lamellibranchiata larvae had main role in formation of zooplankton population in western region of the southern Caspian Sea, but in autumn, 70% of zooplankton population were copepods. The frequency of zooplanktons in spring, summer, autumn and winter were calculated 4081 to 20143; 7812 to 65741; 10850 to 34406 and 4510 to 20576 inch/m^3, respectively. The maximum biomass was observed during summer with 200 mg/m^3

Hydrology and hydrobiology of Chaloos River

The Chaloos River originates from Alborz Mountain and enters into the Caspian Sea in Chaloos city. Five stations were chosen in different areas for the study during 1371 to 1372 (1992-93). Total variation range of hardness decreased 1 to 5 station, but measure NH4 and NO3 increased. 45 genera belongs to 4 phyla of phytoplankton as follows: Chrysophyta, Chlorophyta, Euglenophyta and Cyanophyta. Zooplankton existing in this river belong to animal classes, which had more abundance in Sarcodina and Monogononta. The benthos river establish Insecta larvae of Ephemeroptera, Coleoptera, Diptera, Plecoptera and Odonata (Orders). Chaloos fishes included to 4 families, 10 genera and 12 species. Cyprinidac consisted 66.7% of total fish and had maximum diversity at the various stations

Study of the kinetics and mechanism of rapid self-assembly in block copolymer thin films during solvo-microwave annealing

Microwave annealing is an emerging technique for achieving ordered patterns of block copolymer films on substrates. Little is understood about the mechanisms of microphase separation during the microwave annealing process and how it promotes the microphase separation of the blocks. Here, we use controlled power microwave irradiation in the presence of tetrahydrofuran (THF) solvent, to achieve lateral microphase separation in high- lamellar-forming poly(styrene-b-lactic acid) PS-b-PLA. A highly ordered line pattern was formed within seconds on silicon, germanium and silicon on insulator (SOI) substrates. In-situ temperature measurement of the silicon substrate coupled to condition changes during "solvo-microwave" annealing allowed understanding of the processes to be attained. Our results suggest that the substrate has little effect on the ordering process and is essentially microwave transparent but rather, it is direct heating of the polar THF molecules that causes microphase separation. It is postulated that the rapid interaction of THF with microwaves and the resultant temperature increase to 55 degrees C within seconds causes an increase of the vapor pressure of the solvent from 19.8 to 70 kPa. This enriched vapor environment increases the plasticity of both PS and PLA chains and leads to the fast self-assembly kinetics. Comparing the patterns formed on silicon, germanium and silicon on insulator (SOI) and also an in situ temperature measurement of silicon in the oven confirms the significance of the solvent over the role of substrate heating during "solvo-microwave" annealing. Besides the short annealing time which has technological importance, the coherence length is on a micron scale and dewetting is not observed after annealing. The etched pattern (PLA was removed by an Ar/O-2 reactive ion etch) was transferred to the underlying silicon substrate fabricating sub-20 nm silicon nanowires over large areas demonstrating that the morphology is consistent both across and through the film

Composition and structure of a Fagus orientalis-dominated forest managed with shelterwood aim (A Case study in the Caspian forests, northern Iran)

Composition and structure of a three-storied Fagus orientalis-dominated forest was investigated in the Caspian forests, north of Iran. Circular sampling plots of 1000 m2 occupied by advance growth and natural regeneration were randomly chosen where the initial cuttings (with shelterwood aim) were performed. Abundance of species at different growth stages and quality of seedlings and saplings were registered and basal area and standing volume determined. The measurements were carried out before the first shelterwood cutting (in 1974) and after the last shelterwood cutting (2004). The results after 30 years (in 2004) revealed that frequency, basal area and standing volume significantly enhanced for beech and reduced for hornbeam but did not statistically differ for alder, maple and other species. Sapling and thicket groups were observed in parts of the investigated site and where the mature trees were not felled. Generally, the research area was converted into an irregular uneven-aged 2-4-storied forest, owing to recruits, advance regeneration, aged trees and small and large pole groups maintained through the forest

First Report of Intestinal Myiasis Due To Eristalis tenax in Iran

Eristalis tenax, belonging to order Diptera, family Syrphidae seldomly causes intestinal myiasis. Intestinal myiasis caused by E. tenax larvae is a rare manifestation found in both humans and other vertebrate animals. We report a 22-year-old woman presented with this myiasis. The larva in her stool sample was identified as E. tenax related to its typical morphology and authentic clues. Lack of specific control measures in the domestic water supply system was the most probable cause of this infestation

Hydrological and hydrobiological study in the Syiah-rud River

The study was conducted in Syiah-rud River. The fishes were belonged to five families: Cyprinidae, Atherinidae, Gobiidae, Mugilidae and Cobitidae. The aquatic plants was composed of three groups: marginal, submerged and floating. Among the submerged aquatic plants, potamogetons was the most dominant family and had a large distribution in station IV. 37 genera were also identified from four Algae phylum. There were twelve families in benthos population, which had more abundance in station II. In study of water quality, 15 physical and chemical factors were measured. The highest amount of phosphat was 3.12 mg/1 which was seen in stations III and IV. Also the highest amount of NH4+ and N were seen in station III, probably due to existing sewage factories in this region

Application of mean-field theory to the spin casting of polystyrene and poly(methyl methacrylate) blend films from toluene

The Flory-Huggins free energy of mixing is shown to be appropriate for the analysis of the temporal evolution of a ternary blend of polystyrene and poly (methyl methacrylate) during spin-coating from toluene using an in-situ light scattering technique. For the range of concentrations studied, both the onset of film instability and the observation of a scattering ring occur at the same toluene volume fraction. The success of Flory-Huggins theory indicates that polymer chains retain random walk characteristics during spin-coating. It is also concluded that the thermodynamics of phase separation during film formation is independent of the initial solvent concentration

Pericardial Calcification Associated with Leprosy: A Rare Combination

Majority of pericardial calcifications in the tropics are claimed to be of tuberculous origin. Other known causes include among other things uraemia, asbestosis, and post traumatic/post operative. We report a case of pericardial calcification not associated with constrictive pericarditis seen in a patient with established leprosy. Although a direct causal relationship cannot be established between leprosy and pericardial calcification, the well known condition of cardiac amyloid, a complication of leprosy might have contributed in the pathophysiology of the development of pericardial calcification in our patient. The inclusion of leprosy in the differential diagnosis of the aetiology of pericardial calcification in the tropics is suggested