Akkaya V.R.,Mula Stk Kocman University |
Akkaya V.R.,Kocaeli University |
Kandemir I.,Kocaeli University
Mathematical Problems in Engineering | Year: 2015
Classical solution of Navier-Stokes equations with nonslip boundary condition leads to inaccurate predictions of flow characteristics of rarefied gases confined in micro/nanochannels. Therefore, molecular interaction based simulations are often used to properly express velocity and temperature slips at high Knudsen numbers (Kn) seen at dilute gases or narrow channels. In this study, an event-driven molecular dynamics (EDMD) simulation is proposed to estimate properties of hard-sphere gas flows. Considering molecules as hard-spheres, trajectories of the molecules, collision partners, corresponding interaction times, and postcollision velocities are computed deterministically using discrete interaction potentials. On the other hand, boundary interactions are handled stochastically. Added to that, in order to create a pressure gradient along the channel, an implicit treatment for flow boundaries is adapted for EDMD simulations. Shear-Driven (Couette) and Pressure-Driven flows for various channel configurations are simulated to demonstrate the validity of suggested treatment. Results agree well with DSMC method and solution of linearized Boltzmann equation. At low Kn, EDMD produces similar velocity profiles with Navier-Stokes (N-S) equations and slip boundary conditions, but as Kn increases, N-S slip models overestimate slip velocities. © 2015 Volkan Ramazan Akkaya and Ilyas Kandemir.
Ozgul O.,Mula Stk Kocman University
Zoology in the Middle East | Year: 2015
Hesperinus imbecillus (Loew, 1858) is recorded from Turkey and this represents the first record for this dipteran family in the country. From the family Cylindrotomidae, Cylindrotoma distinctissima distinctissima (Meigen, 1818) is reported from Turkey for the first time and Diogma dmitrii Paramonov, 2005 for the second time. © 2015 Taylor & Francis.
Baskurt S.,Eskiehir Osmangazi University |
Emirolu O.,Eskiehir Osmangazi University |
Tarkan A.S.,Mula Stk Kocman University |
Vilizzi L.,Mula Stk Kocman University
Zoology in the Middle East | Year: 2015
The Roach Rutilus rutilus (Linnaeus, 1758) (Pisces: Teleostei) is a widespread Eurasian cyprinid freshwater fish. Although numerous studies have investigated the species life history traits across its main native range of distribution, little is known from water bodies located beyond the southern limits of the latter, especially where the species has been introduced. Between July 2010 and April 2011, a total of 949 R. rutilus specimens was collected from Porsuk Reservoir (NW Turkey), and life-history traits of age, growth, fecundity and egg size were studied and compared to six other R. rutilus populations (including Caspian Roach R. r. caspicus) from the southern limits of distribution. The Porsuk population was characterised by relatively shorter lifespan, slower growth and lower fecundity. These findings support previous studies emphasising the importance of local environmental factors in shaping the life-history traits of widespread fish species. These must be taken into consideration especially in view of the potential value of R. rutilus as an economic resource for in-land fisheries. © 2015 Taylor & Francis.
Kivrak I.,Mula Stk Kocman University
Journal of Liquid Chromatography and Related Technologies | Year: 2015
Free amino acids of 58 unifloral honeys of 17 different floras (cedar, eucalyptus, vitex, carob, clover, honeydew, sunflower, citrus, heather, thyme, flower, chestnut, sideritis, acacia, lavender, cotton, and mad honeys) from various regions across Turkey were analyzed using ultra performance liquid chromatography with electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS). A method for the determination of free amino acids in honeys was developed and validated. The method comprises sample preparation involving ultrasonic extraction and separation, identification, confirmation, and quantitation. The obtained data have been inquired by principal components analysis (PCA), allowing differentiation of studied honeys by their floral origins. The main amino acids detected in Turkish honeys were phenylalanine (4024.53 mg/kg), proline (1138.18 mg/kg), tyrosine (693.42 mg/kg), and isoleucine (749.81 mg/kg). Thus, the honeys consist of rich free amino acids, and can be accordingly consumed as not only traditional sweeteners, but also supplementary materials for food products especially for foods for children. This method may be used for the determination of individual free amino acids in honeys. © 2015 Taylor and Francis Group, LLC.