Effects of mercury on embryonic development and larval growth of the sea urchin Echinometra mathaei from the Persian Gulf

This study investigated the effects of increasing mercury (Hg) concentration on early developmental stages of sea urchin, Echinometra mathaei, as a bioindicator. The toxicity test was carried out after the gamete released induction and fertilization in six concentrations of mercury within the range of 4, 8, 16, 32, 64 and 128 µg/L. Embryos samples were incubated for 30 h in control and test solutions. After incubation, the percentage of developed 4-arm pluteus larvae was recorded in each group and embryonic abnormalities were studied by a microscope. Results of this study indicate that exposure of embryos to increasing mercury concentrations lead to abnormalities such as changes to shape and size of pluteus larval arms and also arrested development in early embryonic stages. Furthermore, embryos were analyzed to determine mercury absorption by cold vapour atomic absorption spectrometry method (AAS). The median effective concentration (EC50) value calculated for mercury was 17/42 µg/L

DNA Damage of Glioblastoma Multiform Cells Induced by Beta Radiation of Iodine-131 in The Presence or Absence of Topotecan: A Picogreen and Colonogenic Assay

Objective: Glioblastoma multiforme (GBM), one of the most common and aggressive malignant brain tumors, is highly resistant to radiotherapy. Numerous approaches have been pursued to find new radiosensitizers. We used a picogreen and colonogenic assay to appraise the DNA damage and cell death in a spheroid culture of GBM cells caused by iodine-131 (I-131) beta radiation in the presence of topotecan (TPT). Materials and Methods: U87MG cells were cultured as spheroids with approximate diameters of 300 μm. Cells were treated with beta radiation of I-131 (at a dose of 2 Gy) and/ or TPT (1 μg/ml for 2 hours). The numbers of cells that survived were compared with untreated cells using a colonogenic assay. In addition, we evaluated possible DNA damages by the picogreen method. The relation between DNA damage and cell death was assessed in the experimental study of groups. Results: The findings showed that survival fraction (SF) in the I-131+TPT group (39) was considerably less than the I-131 group (58.92; p<0.05). The number of single strand breaks (SSB) and double strand breaks (DSB), in the DNA of U87MG cells treated with beta radiation of I-131 and TPT (I-131+TPT) significantly increased compared to cells treated with only I-131 or TPT (p<0.05). The amount of SSB repair was more than DSB repair (p<0.05). The relationship between cell death and DNA damage was close (r�0.6) and significant (p<0.05) in the irradiated and treated groups. Also the maximum rate of DNA repair occurred 24 hours after the treatments. A significant difference was not observed on other days of the restoration. Conclusion: The findings in the present study indicated that TPT can sensitize U87MG cells to radiation and increase DNA damages. Potentially, TPT can cause an increase in damage from DSB and SSB by its inhibitory effects on topoisomerase enzyme and the cell cycle. The increased complex damages following the use of a genotoxic agent and beta I-131 radiation, causes a significant increase the cell death because of the difficult repair process. By assessing the relationship between DNA damage and cell death, the picogreen method can be useful in predicting colonogenic assay. Consequently, it is suggested that co-treatment with I-131 beta radiation and TPT can improve GBM treatment

Overheating mitigation in buildings: a computational exploration of the potential of phase change materials

Phase change materials (PCMs) can store and release thermal energy. The energy is stored when the material goes through a solid-toliquid phase change, and released in the reverse process. Such materials can contribute to the mitigation of overheating in buildings, if their melting and solidification temperatures are in a suitable range. The present contribution entails a computational examination of this potential as relevant to overheating mitigation in typical residential units in the Central European context of Vienna, Austria. Thereby, multiple variations of PCM application (size, thickness, location, and application thickness) under different contextual settings (fenestration and insulation, boundary conditions in terms of weather) were simulated and comparatively evaluated. Results indicate that certain PCM application configurations can significantly influence indoor thermal condition. For instance, PCM elements with larger surface areas displayed a more pronounced effect as compared to bulkier elements with smaller surface areas. Likewise, ceilingintegrated PCM application was found to be more effective that those involving other room surfaces. The results also highlight the importance of rooms ventilation regime if the PCM application potential toward overheating mitigation is to be effectively harvested

Genotoxic damage to glioblastoma cells treated with 6 MV X-radiation in the presence or absence of methoxy estradiol, IUDR or topotecan

Objective: To explore the cumulative genotoxic damage to glioblastoma (GBM) cells, grown as multicellular spheroids, following exposure to 6 MV X-rays (2 Gy, 22 Gy) with or without, 2-methoxy estradiol (2ME2), iododeoxyuridine (IUDR) or topotecan (TPT), using the Picogreen assay. Materials and Methods: The U87MG cells cultured as spheroids were treated with 6 MV X-ray using linear accelerator. Specimens were divided into five groups and irradiated using X-ray giving the dose of 2 Gy after sequentially incubated with one of the following three drug combinations: TPT, 2-ME2/TPT, IUDR/TPT or 2ME2/IUDR/TPT. One specimen was used as the irradiated only sample (R). The last group was also irradiated with total dose of 22 Gy (each time 2 Gy) of 6 MV X-ray in 11 fractions and treated for three times. DNA damage was evaluated using the Picogreen method in the experimental study. Results: R/TPT treated group had more DNA damage double strand break (DSB)/single strand break (SSB) compared with the untreated group (P<0.05). Moreover the R/TPT group treated with 2ME2 followed by IUDR had maximum DNA damage in spheroid GBM indicating an augmented genotoxicity in the cells. The DNA damage was induced after seven fractionated irradiation and two sequential treatments with 2ME2/IUDR/TPT. To ensure accuracy of the slope of dose response curve the fractionated radiation was calculated as 7.36 Gy with respect to α/β ratio based on biologically effective dose (BED) formulae. Conclusion: Cells treated with 2ME2/IUDR showed more sensitivity to radiation and accumulative DNA damage. DNA damage was significantly increased when GBM cells treated with TPT ceased at S phase due to the inhibition of topoisomerase enzyme and phosphorylation of Chk1 enzyme. These results suggest that R/TPT-treated cells increase sensitivity to 2ME2 and IUDR especially when they are used together. Therefore, due to an increase in the level of DNA damage (SSB vs. DSB) and impairment of DNA repair machinery, more cell death will occur. This in turn may improve the treatment of GBM. © 2015, Royan Institute (ACECR). All rights reserved

Evidence for Non-Hydrostatic Gas from the Cluster X-ray to Lensing Mass Ratio

Using a uniform analysis procedure, we measure spatially resolved weak gravitational lensing and hydrostatic X-ray masses for a sample of 18 clusters of galaxies. We find a radial trend in the X-ray to lensing mass ratio: at r2500 we obtain a ratio MX/ML=1.03+/-0.07 which decreases to MX/ML=0.78+/-0.09 at r500. This difference is significant at 3 sigma once we account for correlations between the measurements. We show that correcting the lensing mass for excess correlated structure outside the virial radius slightly reduces, but does not eliminate this trend. An X-ray mass underestimate, perhaps due to nonthermal pressure support, can explain the residual trend. The trend is not correlated with the presence or absence of a cool core. We also examine the cluster gas fraction and find no correlation with ML, an important result for techniques that aim to determine cosmological parameters using the gas fraction.Comment: 8 pages, minor modifications, accepted for publication in MNRA

AN EFFECTIVE OPTIMIZATION ALGORITHM FOR LOCALLY NONCONVEX LIPSCHITZ FUNCTIONS BASED ON MOLLIFIER SUBGRADIENTS

We present an effective algorithm for minimization of locally nonconvex Lipschitz functions based on mollifier functions approximating the Clarke generalized gradient. To this aim, first we approximate the Clarke generalized gradient by mollifier subgradients. To construct this approximation, we use a set of averaged functions gradients. Then, we show that the convex hull of this set serves as a good approximation for the Clarke generalized gradient. Using this approximation of the Clarke generalized gradient, we establish an algorithm for minimization of locally Lipschitz functions. Based on mollifier subgradient approximation, we propose a dynamic algorithm for finding a direction satisfying the Armijo condition without needing many subgradient evaluations. We prove that the search direction procedure terminates after finitely many iterations and show how to reduce the objective function value in the obtained search direction. We also prove that the first order optimality conditions are satisfied for any accumulation point of the sequence constructed by the algorithm. Finally, we implement our algorithm with MATLAB codes and approximate averaged functions gradients by the Monte-Carlo method. The numerical results show that our algorithm is effectively more efficient and also more robust than the GS algorithm, currently perceived to be a competitive algorithm for minimization of nonconvex Lipschitz functions

Modeling and verification of response of RC columns strengthened in flexure with mechanically fastened FRP

One of the most important challenges exists in using of carbon fiber reinforced polymer(FRP) for strengthening of concrete members is the brittle behavior of RC members due to premature de-bonding of the layers. Mechanically fastened FRP (MF-FRP) systems are emerging as a promising method to prevent de-bonding of FRP strips and the prior brittle failure of strengthened RC members. The approach entails the use of fiber-reinforced polymer connected to the concrete substrate by means of steel anchors. In this research, a new anchor designed to delay de-bonding of FRP in reinforced concrete (RC) strengthened columns. Two reinforced concrete columns strengthened using the externally bonded conventional method and the new proposed method in comparison with unstrengthened RC column in the Laboratory. Specimens subjected to constant axial loading and cyclic lateral loading. Besides, numerical simulations performed using finite element models for nonlinear analyses of RC specimens: un-strengthened column; the column strengthened conventionally EB method and the column using new MF method

Harnessing buildings' operational diversity in a computational framework for high-resolution urban energy modeling

To achieve computational efficiency, efforts toward developing urban-scale energy modeling applications frequently rely on various domain simplifications. For instance, heat transfer phenomena are captured using reduced order models. As a consequence, specific aspects pertaining to the temporal dynamics of energy load patterns and their dependency on transient phenomena (e.g., weather conditions, inhabitants’ presence and actions) cannot be realistically represented. To address this circumstance, we have conceived, implemented, and documented a two-step urban energy modeling approach that combines cluster analysis and sampling techniques, full dynamic numeric simulation capability, and stochastic methods. The paper describes the suggested urban energy modeling approach and the embedded cluster analysis supported sampling methodology. More particularly we focus on the aspects of this approach that explicitly involve the representation of inhabitants in urban-scale energy modeling. In this regard, the potential to recover lost dynamic diversity (e.g., in computation of temporal load patterns) due to the deployed reductive sampling is explored. Parametric runs based on stochastic variations of underlying building use profiles facilitate the generation of highly realistic load patterns despite the small number of buildings selected to represent the simulation domain. We illustrate the utility of the proposed urban energy modeling approach to address queries concerning the energy efficiency potential of behaviorally effective instruments. The feasibility of the envisioned scenarios concerning inhabitants and their behavior (high-resolution temporal load prediction, assessment of behavioral variation) is presented in detail via specific instances of district-level energy modeling for the city of Vienna, Austria