Investigation of stock condition of Lengeh pearl oyster Pinctada radiata in western Hormozgan province habitats with emphasis on ecological agents

Pearling in Northern Persian Gulf has barred since 2006. Population dynamic and investigation of stock condition of pearl oysters has not done in thease area in thease years heretofore. For identification of habitats of Pinctada radiata, mohar oyster, primary sea tours in coastal waters of 11 regions in Lavan Island, 11 regions in hendorabi Island and 6 regions in Nakhiloo and Michaeil Ports, for early survey were done. 2 habitats in Lavan waters and 2 habitats in Hendorabi waters were identified and for investigation of stock condition, were sampled from autumn 2011 to summer 2012, seasonality. Belt transects andrandom quadrates method was used in this sampling. Physicochemical parameters in depth range of thease habitats was evaluated by CTD in first sea tour of stock sampling. Lavan 1 habitat, had maximum area, maximum total stock, maximum CPUA, maximum CPUE and maximum biomass, among other habitats, equal to 60ha, 357000N, 0.6N/m^2, 119N/hr and 4620kg respectively. Biometric data in Hendorabi2 habitat was rather than other habitats, significantly (P<0.01). Infinity length, L_∞, was calculated in Lavan1, Lavan2, Hendorabi1 and Hendorabi2 habitats, equal to 89.16, 87.68, 86.11 and 86.42 mm respectively. Growth constant, K, was estimated in Lavan1, Lavan2, Hendorabi1 and Hendorabi2 habitats, equal to 0.43, 0.44, 0.47 and 0.56 year^-1, respectively. Natural mortality constant, M, was calculated in Lavan1, Lavan2, Hendorabi1 and Hendorabi2 habitats, equal to 0.73, 0.75, 0.78 and 0.88 year^-1, respectively. Results of this project showed, area of investigated habitats, oysters stock of them and CPUA, have diminished in thease years, and interdict of pearl oysters catch was not able to revival of stocks. Majority of physicochemical parameters in depth ranges in surveyed habitas, had significant difference (P<0.01). Water turbidity in Hendorabi2 habitat was rather than other habitat, significantly (P<0.01), as subsidiary of high sedimentation in this habitat and main reason of high natural mortality constant, M, low settlement rate and absence of lower scale of oysters length in Hendorabi2 habitat

A Comparative Study of Photo-Degradation of Atrazine in Aquatic Environments Using UV and UV/Fe (III)-TiO2 Processes

A vast variety of pesticides are used for agricultural pests in Iran. The release of these persistent organic pollutants into water supplies leaves adverse effects on both the environment and public health. This study aimed to compare the photo-degradation of atrazine in the aquatic environment using UV and UV/Fe (III)-TiO2 processes. The effects of parameters including pH, the initial concentration of atrazine, and reaction time on the removal of atrazine in the aqueous phase using ultraviolet radiation (1020 μW/cm2) and UV/Fe (III)-TiO2 were investigated. Residual concentrations were determined using HPLC. Finally, the data were analyzed using SPSS software (version 16) and the graph was made by MATLAB software. The results demonstrated that the atrazine removal rate in both processes was significantly increased in acidic and alkaline conditions. By increasing initial atrazine concentrations, the removal rate was increased in both processes as well. Data showed that at the lower initial concentration of atrazine (0.1 and 1mg/l) the removal rate in UV/ Fe (III) - TiO2 process was more than the UV process. However, at higher concentration, both processes were almost the same and the maximum removal efficiency (99.2% at UV and 99.11% at UV /Fe (III) - TiO2) occurred at pH=11, initial Atrazine concentration of 10mg/L and the reaction time 30 min In conclusion, UV and Fe+3-TiO2/UV process was an appropriate method to reduce atrazine in contaminated water resources

Time-resolved spectroscopy of some transient molecules

Bibliography: p. 82-87We have developed a time-resolved gated-integration method where the growth or decay of the concentration of a given transient molecule in a hollow cathode discharge can be monitored. Two identical boxcars integrators provide two gates with predetermined widths, one monitoring end of discharge-off period (where no absorption takes place) and the other measuring at the absorption signal at a given delay time with respect to the discharge stop time. Then, by subtracting/dividing the two signals, the growth or decay of the concentration of the studied molecule is obtained. Decay of the concentration of C3 was found to be relatively long, on the order of millisecond. This decay was studied as a function of helium buffer gas pressure (10, 15 and 20 Torr). A linear dependency of the lifetime vs. buffer gas pressure was observed. Also, lifetimes of 24.5(1.5) ?s and 21 (1) ?s were measured for the two short-lived molecular ions H3 + and HN2 +, respectively

Fracture analysis of V‐notched rubbers: An experimental and theoretical study

In this study, the rupture load in rubbers weakened by sharp V‐notch is investigated under mode I loading. To this end, first, mode I fracture tests are performed on V‐notched samples made of styrene‐butadiene rubbers and the corresponding rupture loads are obtained. Then, the effective stretch (ES) criterion, which was recently developed by the present authors for rupture assessment of cracked rubber parts, is extended and used for the V‐notched rubbers. It is shown that similar to cracked rubbers, the state of stress near the notch tip is also nearly uniaxial. By employing the ES criterion, the critical displacements corresponding to the rupture in the tested samples are calculated. Finally, the predictions of the criterion are compared with the corresponding experimental values, and good consistency is shown to exist.submittedVersionThis is the pre-peer reviewed version of an article, which has been published in final form at [https://doi.org/10.1111/ffe.12947]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving

Influence of Surface Grafted Polymers on the Polymer Dynamics in a Silica–Polystyrene Nanocomposite: A Coarse-Grained Molecular Dynamics Investigation

Performing coarse-grained molecular dynamics simulations, the local dynamics of free and grafted polystyrene chains surrounding a spherical silica nanoparticle has been investigated, where the silica nanoparticle was either bare or grafted with 80-monomer polystyrene chains. The effect of the free (matrix) chain molecular weight and grafting density on the relaxation time of both the free and grafted polystyrene chains has been investigated. Furthermore, we have analyzed the local mobility of the grafted chains at different separations from the nanoparticle surface, as well as on the mean square displacement of the nanoparticles. Proximity to the surface, confinement by the surface, increased grafting density and increased matrix chain length were found to slow down the dynamics of the chain monomers and hence to increase the corresponding relaxation times. “Drying” of the grafted network of the nanoparticle via increasing the free chain lengths, which is known to shrink the brush-height, was found to slow down the relaxation of the brushes, too. The thickness of the interphase, beyond which the polymers showed bulklike behavior, was ∼2 nm for a bare nanoparticle, corresponding to four monomer layers, for all matrix chain lengths investigated. It increased to ∼3 nm for grafted nanoparticles depending on the grafting density and the matrix chain molecular weight

A New Criterion for Rupture Assessment of Rubber-Like Materials under Mode-I Crack Loading: The Effective Stretch Criterion

A new criterion is presented for fracture assessment of rubber-like materials weakened by a mode I crack. The criterion is based on two main assumptions: the existence of a damage zone around the crack tip and the dominant uniaxial nature of the stress field near the crack in rubber-like materials. Considering these key features and employing the concepts of well-known eight-chain model, first, a failure criterion called the "Effective Stretch Criterion" has been proposed. Then, a procedure has been elaborated to calibrate the material parameters in the criterion. The criterion, finally, has been validated by using two sets of experimental data available in the literature