Elastic instability in stratified core annular flow

We study experimentally the interfacial instability between a layer of dilute polymer solution and water flowing in a thin capillary. The use of microfluidic devices allows us to observe and quantify in great detail the features of the flow. At low velocities, the flow takes the form of a straight jet, while at high velocities, steady or advected wavy jets are produced. We demonstrate that the transition between these flow regimes is purely elastic -- it is caused by viscoelasticity of the polymer solution only. The linear stability analysis of the flow in the short-wave approximation captures quantitatively the flow diagram. Surprisingly, unstable flows are observed for strong velocities, whereas convected flows are observed for low velocities. We demonstrate that this instability can be used to measure rheological properties of dilute polymer solutions that are difficult to assess otherwise.Comment: 4 pages, 4 figure

Age and growth of four-spotted megrim (Lepidorhombus boscii Risso, 1810) from Saros Bay (Northern Aegean Sea, Turkey)

In this study, the growth parameters of the four-spotted megrim, (Lepidorhombus boscii Risso, 1810), were studied in Saros Bay, which had been closed to bottom trawl fishery since 2000. The sex ratio of females to males was 1:0.42. Length-weight relationships were W=0.0032L3.31 and W=0.0069L3.04 for females and males, respectively. Growth parameters of the populations were L∞=49.8 cm, k=0.09 year-1, t0=-2.15 year for females; L∞=39.1 cm, k=0.11 year-1, t0=-2.59 year for males. The growth performance index (Φ’) was found to be 2.35 and 2.23 for females and males, respectively

Age and growth of four-spotted megrim (Lepidorhombus boscii Risso, 1810) from Saros Bay (Northern Aegean Sea, Turkey)

In this study, the growth parameters of the four-spotted megrim, (Lepidorhombus boscii Risso, 1810), were studied in Saros Bay, which had been closed to bottom trawl fishery since 2000. The sex ratio of females to males was 1:0.42. Length-weight relationships were W=0.0032L3.31 and W=0.0069L3.04 for females and males, respectively. Growth parameters of the populations were L∞=49.8 cm, k=0.09 year-1, t0=-2.15 year for females; L∞=39.1 cm, k=0.11 year-1, t0=-2.59 year for males. The growth performance index (Φ’) was found to be 2.35 and 2.23 for females and males, respectively

Enhancing gas sepration across a membrane with pulsating flow

Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.Gas-gas separation is a critical process in natural gas purification. Removing acidic gasses from natural gas is particularly important to protect the pipeline from corrosion. Using a membrane to purify natural gas is receiving a lot of attention recently. Membrane performance can be enhanced by either improving the permeability or the selectivity of the membrane or by enhancing the momentum mixing in the bulk flow. Our work will focus on improving membrane performance by enhancing momentum mixing in the bulk flow for gas-gas separation to purify natural gas. Pulsating flow in a channel with turbulators will be considered. Computational fluid dynamics simulation will be conducted for turbulent flow of multicomponent fluid including mass transfer of each species. RANS -Reynolds-Averaged Navier-Stokes equation along with mass transport equation will be employed to simulate 2-D transient turbulent flows of bulk fluid. The membrane will be modeled as a functional surface where the flux of each component will be determined based on the local partial pressure of each species, composition, and permeability and selectivity of the membrane. The performance of the system will be measured by maximum mass separation with minimal frictional losses.cf201

Determining the hook selectivity of bottom longline used for European hake (Merluccius merluccius, L. 1758) in Saros Bay (northern Aegean Sea, Turkey)

This study was carried out at Saros Bay, between June 2011 and July 2013 to determine hook selectivity of bottom longlines used in European hake (Merluccius merluccius, L. 1758) fishing. Throughout the study; thick type, 6, 7, 8 and 9 sized flat hooks were used between 150 and 400 m depth. 36 fishing operations were carried out and 222 fish were caught using 7200 hooks in total. Depending on the size of hooks; number 8 was the most efficient hook that has caught 114 fish and number 6 was the least efficient one that has caught only 14 fish. The SELECT method is used in the determination of the selectivity parameters. Bi model has given the best fit according to selectivity analysis of five different models. Optimum catching lengths found were 60.09 cm for 6 number hook; 51.45 cm for 7 number hook; 46.43 cm for 8 number hook; 40.11 cm for 9 number hook, in Bi Model model. Minimum size limit for European hake is 25 cm in Turkey. Considering the minimum size limit, use of hooks with gapes larger than number 9 hook (11.75 mm) used in this study is suggested.[ARGE 11/16]This study was summarized from the A Oztekin's PhD thesis entitled Determining fishing compositions and selectivity of bottom long line kits used in North Aegean Sea carried out with financial support of (TAGEM project number: ARGE 11/16)

Length-weight relationships of 17 less-studied fish species from Canakkale, Marmara region of Turkey

This study reports length-weight relationships for 17 cryptic and rare species, Aidablennius sphynx, Arnoglossus kessleri, Callionymus pusillus, Callionymus risso, Clinitrachus argentatus, Echiichthys vipera, Gobius geniporus, Gobius paganellus, Labrus viridis, Lepadogaster lepadogaster, Ophidion barbatum, Pomatoschistus minutus, Pomatoschistus pictus, Salaria pavo, Tripterygion delaisi, Tripterygion tripteronotus and Zebrus zebrus from Canakkale near shores in the Marmara region of Turkey.TUBITAK [106T123]This study was supported by TUBITAK (Project No. 106T123). The authors thank Alptekin Erdem and Muge Cetin for their help in the laboratory

Interaction between ABA and cytokinins in salinized tomato plants

Abscisic acid (ABA) and cytokinins (CKs) are phytohormones that mediate plant responses to abiotic stress and are mainly considered to be produced in roots. These two plant hormones have long been considered antagonists, but the role of this antagonism in mediating abiotic stress resistance remains unknown. In this study we have used reciprocal grafting of transgenic lines with altered hormone synthesis (ABA or CK synthesis) with the aim of assessing the importance of ABA and CK interaction in mediating plant salinity responses in tomato. Preliminary results have shown a negative effect in ABA and CK on tomato plant biomass under salinity. Results have also indicated that jasmonic acid (JA) might be involved in the negative impact on tomato growth caused by ABA and CK interaction under salt conditions.The authors thank Andrew J. Thompson, from Cranfield Univertity (UK), and Ann C. Smigocki from Molecular Plant Pathology Laboratory (EEUU) the NCED and IPT seeds sets respectively. This work was supported by CICYT AGL2011‐27996 and ROOTOPOWER (REF: 289365. FP7‐KBBE‐2011‐5 European Union)

Is bendopnea associated with atrial fibrillation in heart failure patients with reduced ejection fraction?

[Anstract Not Available

Effect of Pentoxifylline on Antioxidant Status of Healthy and Endotoxemic New Zealand White Rabbits

In this study, effect of pentoxifylline on antioxidant status of healthy and endotoxemic rabbits was investigated. Endotoxemia was induced with E. coli lipopolysaccharide in New Zealand white rabbits. Forty rabbits were randomly divided into four equal groups. Group 1 served as control. Animals in Group 2 were given lipopolysaccharide (400 mu g/kg) intravenously, in Group 3 pentoxifylline (50 mg/kg) was injected intraperitoneally. In Group 4; pentoxifylline (50 mg/kg intraperitoneally) and lipopolysaccharide (400 mu g/kg, intravenously) were injected simultaneously. Animals were killed, and liver, heart and kidney samples were taken at 6 hours after administrations. Malondialdehyde, superoxide dismutase, glutathione peroxidase and reduced glutathione levels of heart, liver and kidney tissues were measured. Lipopolysaccharide caused significant increases (p < 0.05) in hepatic malondialdehyde, and cardiac, hepatic and renal glutathione peroxidase activities. It however, caused significant (P < 0.05) decrease in hepatic superoxide dismutase activity when compared to control group. Pentoxifylline caused significant (p < 0.05) increases of cardiac and hepatic malondialdehyde levels, cardiac superoxide dismutase and renal glutathione peroxidase activities, and cardiac, hepatic and renal reduced glutathione levels when compared to control group. As a result, pentoxifylline has no exactly beneficial effect on the antioxidant status of healthy and endotoxaemic New Zealand white rabbits at the administered dose and route. Although it was stated that pentoxifylline may be beneficial in endotoxaemia, its antioxidant effect may be dependent on dose, administration route and animal species. For this reason, when pentoxifylline is used in endotoxaemia, a treatment protocol should be done for each animal species