Cell sheet engineering: solvent effect on nanometric grafting of poly-n-isopropylacrylamide onto polystyrene substrate under ultraviolet radiation

Esmaeil Biazar1, MT Khorasani2, M Daliri31Department of Biomedical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran; 2Biomaterial Department, Iran Polymer and Petrochemical Institute, Tehran, Iran; 3National Research Center for Genetic Engineering and Biotechnology, Tehran, IranBackground: The best solvent type and ratio for grafting of poly-n-isopropylacrylamide (PNIPAAm) on the surface of polystyrene is obtained under ultraviolet radiation. In this study, the effects of solvents, such as water, methanol, and their combinations, under ultraviolet radiation were investigated successfully.Method and results: Attenuated total reflection Fourier transform infrared analysis showed the existence of the graft PNIPAAm on the substrate for all samples resolved in solvents. The best solvent ratio and NIPAAm concentration for grafting was obtained with 40% NIPAAm concentrations resolved in a solvent of 9:1 (v/v) water/methanol (120%). Scanning electron microscopic and atomic force microscopic images clearly showed that a 10% increase of methanol to water would increase the amount of grafting. Surface topography and graft thickness in atomic force microscopic images of the grafted samples showed that the thickness of these grafts was about 600 nm. The drop water contact angles of the best grafted sample at 37°C and 4°C were 43.3° and 60.4°, respectively, which demonstrated the hydrophilicity and hydrophobicity of the grafted surfaces. Differential scanning calorimetric analysis also revealed the low critical solution temperature of the grafted sample to be 32°C. Thermoresponsive polymers were grafted to dishes covalently, which allowed epithelial cells to attach and proliferate at 37°C. The cells were also detached spontaneously without using enzymes when the temperature dropped below 4°C.Conclusion: MTT analysis also showed good viability of cells on the grafted samples, suggesting that this type of grafted material had potential as a biomaterial for cell sheet engineering.Keywords: nanometric grafting, solvent effect, poly-n-isopropylacrylamide, polystyrene film, ultraviolet radiatio

Promoting governability in small-scale capture fisheries in the Persian Gulf: The case of Qeshm Island

Source at http://jifro.ir/index.php?slc_lang=en&sid=1.The present study examines the fisheries governance status of small-scale capture fisheries in the northern Persian Gulf. Qeshm Island, which is selected as case study, plays a prominent role in fisheries in the Persian Gulf and territorial waters of the country. The research methodology included in-depth and semi-structured interviews with heads of fisheries cooperatives and fishers to deepen our understanding of the cultural and technical characteristics of local fisheries communities. Subsequently, data was drawn from 322 questionnaires, using a random sampling technique. The analyses indicate that fisheries co-management is at an interstitial situation, while the fishers are willing to cooperate with the government. A finding is also showed that literacy has a significant effect on fishers’ willingness to cooperate with government. There was also a considerable conflict of interest among the fisheries communities in the study area, which makes the implementation of rules difficult. Small-scale fishing communities are generally in a hard-pressed situation, which affects how fishers operate. Our study aims to contribute to improving the governance and governability of small-scale capture fisheries in the region

Length-weight and length-length relationships, relative condition factor and Fulton’s condition factor of five Cyprinid species in Anzali wetland, southwest of the Caspian Sea

This study was conducted to determine length-weight and length-length relationships, relative condition factor (Krel) and Fulton’s condition factor (K) for five species including Scardinius erythrophtalmus, Carassius auratus gibelio, Cyprinus carpio, Tinca tinca and Hemiculter leucisculus belonging to Cyprinidae family. Fish sampling was carried out by gill net and fyke net in the western region of Anzali wetland (SW of the Caspian Sea) between Nov. 2010 and May 2011. 368 specimens were measured and weighed. The values of the exponent b in the length-weight relationships (LWRs) ranged from 2.5358 to 3.3613 and those of the length-length relationship (LLRs) ranged from 0.8717 to 0.9412. Also, relative condition factor (Krel) ranged from 1.00±0.11 to 1.30±0.21 and Fulton’s condition factor (K) ranged from 0.80±0.05 to 1.60±0.18 for all species

Chitinase isolated from water and soil bacteria in shrimp farming ponds

Chitinases have received attention because of their wide applications in the medicine, biotechnology, agriculture, waste management and industrial applications such as food quality enhancer and biopesticide. Excessive use of insecticides has led to several problems related to pollution and environmental degradation. In this study, isolation and identification of native bacterial strains with chitin hydrolysis activity, took place from water and soil of shrimp culture ponds in Bushehr and Abadan. To investigate the capacity of our chitinase for using in insecticide, biochemical properties of selected chitinase obtained in this research were compared to that of produced by Bacillus cereus p-1, isolated from an insecticide tablet. In this research, three mesophilic strains containing: Serratia marcescens B4A, Citrobacter freundii B1A and Bacillus cereus B3R were isolated. Results showed a 1600 bp band corresponding to chitinase gene. The similarity between temperature and pH profile and stability of chitinase was extracted from native bacteria and ones was obtained from Bacillus cereus p-1 implied that chitinase extracted from Serratia marcescens B4A has potential application in industry

Magneto-hydrodynamics of couple stress lubricants in combined squeeze and shear in parallel annular disc viscous coupling systems

This article presents predictive analysis of load-carrying capacity, tractive efficiency and response time of parallel annular discs intervened with a film of lubricant under combined shear and squeeze film motions. This configuration represents operational characteristics of viscous coupling systems. In particular, the case of viscous dampers for tractive torque generation and distribution in all-wheel-drive off road vehicles is studied. Various forms of lubricant behaviour, from idealised Newtonian to that of non-Newtonian silicone-based fluids and incompressible isothermal electrically conducting couple stress fluids, subjected to a magneto-hydrodynamic field are studied. The solution for the magneto-hydrodynamics includes combined solution of modified Reynolds equation and Stoke's micro-continuum for couple stress fluids in squeeze and shear with rotational fluid inertia, an approach not hitherto reported in the literature. It is shown that in general magneto-hydrodynamic couple stress fluids enhance the load-carrying capacity of the contact and inhibit the incidence of thin films, which can result in direct contact of surfaces. Rotational inertia decreases the load-carrying capacity, although in general the magneto-hydrodynamic fluids show better load-carrying capacity and tractive efficiency than the other alternatives. However, they exhibit a lower response time under the assumed isothermal condition. Nevertheless, the magneto-hydrodynamic fluids are best suited to applications in viscous coupling systems because of their controllability

Arsenic contamination at the Bagnoli Bay seabed (South Italy) via particle tracking numerical modeling: Pollution patterns from stationary climatic forcings

Almost 140 years of industrial exploitation have severely degraded the environment of Bagnoli Coroglio (BC), the westernmost neighborhood of the city of Naples (Italy). In this peculiar area, however, geogenic processes overlap with the impact of human activities, making it difficult to distinguish between anthropogenic and geogenic pollution sources. This is particularly true for Arsenic, the concentration of which in the marine sediments largely exceeds the tolerable level for human health and the background value for local pyroclastics. After several studies have used traditional tools based on multivariate statistics, this article attempts at tackling the problem via numerical modeling, which provides a deeper insight into the physics that governs the pollution process. Therefore, we use a particle tracking model to assess whether arsenic levels in the seabed can be affected by the influx of thermal water from an artificial channel outfalling at the westernmost part of the coast The climatic forcings that drive the marine circulation are simplified to basic “scenarios”, in which wind and waves are stationary in strength and direction. Since the simulation time is much less than the contamination timescale, the comparison between numerical results and measurements is essentially qualitative and concerns the shape of contamination contours

Multiscale Fluctuation Dispersion Entropy of EEG as a Physiological Biomarker of Schizotypy

Altered electroencephalography (EEG) activity in schizotypal individuals is a powerful indicator of proneness towards psychosis. This alteration is beyond decreased alpha power often measured in resting state EEG. Multiscale fluctuation dispersion entropy (MFDE) measures the non-linear complexity of the fluctuations of EEGs and is a more effective approach compared to the traditional linear power spectral density (PSD) measures of EEG activity in patients with neurodegenerative disorders. In this study, we applied MFDE to EEG signals to distinguish high schizotypy (HS) and low schizotypy (LS) individuals. The study includes several trials from 29 participants psychometrically classified as HS (n=19) and LS (n=10). After preprocessing, MFDE was computed in frontal, parietal, central, temporal and occipital regions for each participant at multiple time scales. Statistical analysis and machine learning algorithms were used to calculate the differences in MFDE measures between the HS and LS groups. Our findings revealed significant differences in MFDE measures between LS and HS individuals in the delta frequency band (at time scale 100 ms). HS individuals exhibited increased complexity and irregularity compared to LS individuals in the delta frequency band particularly in the occipital region. Furthermore, the MFDE measures resulted in high accuracy (96.55%) in discriminating between HS and LS individuals and outperformed the models based on power spectrum, demonstrating the potential of MFDE as a neurophysiological marker for schizotypy traits. The increased non-linear fluctuation in delta frequency band in the occipital region of HS individuals implies the changes in cognitive functions, such as memory and attention, and has significant potential as a biomarker for schizotypy and proneness towards psychosis

Effects of exposure to dmso in vitrification solution on cytotoxicity and in vitro viability of immature bovine oocyte.

Based on previous studies for vitrification of oocytes, it has been shown that short term exposure to DMSO during vitrification could improve the maturation rate and cause not spontaneous parthenogenesis (Isachenko et al., 2006). In addition, it was reported that DMSO in freezing media caused disassembly of microfilaments and chromosomal abnormalities in mouse oocytes (Vincent et al., 1990). On the other hand, DMSO is categorized as a potent glass former and its existence in vitrification solution seems necessary. The aim of this study was to determine the in vitro viability of immature bovine oocytes vitrified by short or long time exposure to DMSO. Materials and Methods: Cumulus oocytes complexes (COCs) with homogenous ooplasm were recovered from slaughterhouse ovaries and used in this study. The vitrification protocol was adapted from Kuwayama et al (2005) with minor modifications. Briefly, oocytes were washed twice in holding solution (HS, Hepes-buffered TCM medium supplemented with 20% fetal calf serum, FCS) and kept there for about 15 min. Group of four COCs were incubated in the first vitrification solution (VS1; 7.5% DMSO and 7.5% EG in HS) for 12 min. Equilibration in VS1 was performed in three steps of increasing concentration. First (F) and second (S) steps contained 1/3 and 2/3 of VS1 diluted in HS, and the third (T) step contained only pure VS1. Based on removal of DMSO from each step, five treatment groups were designed: (G1) control, (G2) VS1, (G3) F w/o DMSO, (G4) F+S w/o DMSO, and (G5) F+S+T w/o DMSO. For G3, G4 and G5, similar concentration of EG was added to replace DMSO in VS1. All treatment groups were equilibrated into the second vitrification solution (VS2; 15% DMSO, 15% EG and 0.5M sucrose in HS) for a further 60 sec. Two experiments were performed: (a) cytotoxicity after only exposure, and (b) in vitro viability after vitrification processes. In cytotoxicity test, immature oocytes were directly transferred to the warming solution (WS). In vitrification experiment, oocytes were instantly loaded on a Cryotop device and submerged into liquid nitrogen (LN2) for storage. The time of exposure from VS2 to LN2 was not longer than 90 s. Vitrified samples were maintained in LN2 for at least 10 days. Immediately after removing the Cryotop from LN2, thin strip of Cryotop was submerged in 3 ml HS plus 1M sucrose (WS; 39°C) and smoothly tried to detach oocytes from Cryotop device. Immature oocytes were left in WS for one minute and then transferred to HS plus 0.5M and 0.15M sucrose solution for 3 and 5 min, respectively. Finally, the immature oocytes were washed twice in HS for 5 min each and processed for in vitro maturation. Significant differences among treatments used in the experiment were revealed by one-way analysis of variance and followed by Duncan's multiple range test for mean comparisons (P < 0.05) using SAS software (ver. 9.1)

Nuclear maturation of immature bovine oocytes after vitrification using open pulled straw and cryotop methods

To date, at least two well known methods have been widely used for vitrification of oocytes and embryos at different stages in a variety of species. However, there is no reported data regarding the comparative effectiveness of these two methods for vitrification of immature bovine oocytes. The objective of this study is to compare the nuclear maturation of immature bovine oocytes vitrified using open pulled straw (OPS) and cryotop methods. Two experiments were conducted in this study. In the first experiment, cytotoxicity of vitrification solutions (VS) from both methods was studied. After removal of cryoprotectants, cumulus oocyte complexes (COCs) was cultured in vitro and cleavage rate was monitored on Day 2 post-insemination (pi), whereas, morulae and blastocyst yields on Days 5 and 8 pi, respectively. The VS solutions significantly reduced zygotic cleavage rate, morulae and blastocyst rates compared with the control group (P &lt; 0.05). The lowest cleavage rate resulted from prolonged exposure time to OPS-VS solutions (35.1%; P &lt; 0.05). However, the morulae and blastocyst rates were significantly higher (P &lt; 0.05) for embryos derived from oocytes exposed to cryotop solutions (40.5 and 22.4%, respectively). In the second experiment, effectiveness of both vitrification methods was compared for cryopreservation of immature bovine oocytes. After warming, COCs were cultured in vitro for 24 h. The polar body (PB+) and metaphase-II (MII) stage rates differed significantly among treatment groups. Oocytes vitrified using cryotop solution and device showed higher percentages of PB+ (36%) and MII (51%) rates. In addition, the lowest percentage of degenerated oocytes resulted from cryotop solution. The highest degenerated oocytes obtained by equilibration in OPS solution and vitrified using OPS device (40%; P &lt; 0.05). In conclusion, our data demonstrated that cryotop solution was less toxic to the immature bovine oocytes and vitrification with the cryotop method resulted in higher survival and nuclear maturation rates.Key words: Immature oocyte, bovine, vitrification, cryotop, open pulled straw (OPS)