Interaction Between Motor Domains Can Explain the Complex Dynamics of Heterodimeric Kinesins

Motor proteins are active enzyme molecules that play a crucial role in many biological processes. They transform the chemical energy into the mechanical work and move unidirectionally along rigid cytoskeleton filaments. Single-molecule experiments suggest that motor proteins, consisting of two motor domains, move in a hand-over-hand mechanism when each subunit changes between trailing and leading positions in alternating steps, and these subunits do not interact with each other. However, recent experiments on heterodimeric kinesins suggest that the motion of motor domains is not independent, but rather strongly coupled and coordinated, although the mechanism of these interactions are not known. We propose a simple discrete stochastic model to describe the dynamics of homodimeric and heterodimeric two-headed motor proteins. It is argued that interactions between motor domains modify free energy landscapes of each motor subunit, and motor proteins still move via the hand-over-hand mechanism but with different transitions rates. Our calculations of biophysical properties agree with experimental observations. Several ways to test the theoretical model are proposed.Comment: To appear in New J. Phy

Effect of different levels of royal jelly on biochemical parameters of swimmers

This study aims to investigate the effects of different levels of royal jelly supplementation on biochemical parameters in swimmers. Randomly selected 40 male swimmers aged 18 to 25 years attending the same trainings were recruited. Swimmers were assigned to 4 groups each with 10 subjects. Varying amounts of royal jelly (2, 1 g and 500 mg) were given to the 1st, 2nd and 3rd groups and placebo (corn starch) to the 4th group. Participants were trained by swimming totally 20 km in 2 h on 5 days a week for 4 weeks. Resting blood samples were taken before royal jelly administration and after 30 days of application. Then biochemical analyses were performed. Different levels of royal jelly were found to be ineffective on glucose, total cholesterol, high density lipoprotein (HDL) cholesterol, low density lipoprotein (LDL) cholesterol, lactate dehydrogenase (LDH), creatine kinase (CK), aspartate aminotransferase (AST), alanine aminotransferase (ALT) levels of the swimmers. Blood urea nitrogen (BUN) and creatinine levels increased after the training program, and BUN level was higher in the group receiving 500 mg royal jelly than those in the other groups. The increment in creatinine levels was higher in those groups receiving higher amounts of royal jelly after the training. A supplementation of 500 mg, 1 and 2 g/day of royal jelly throughout the 30 day-exercise program was not significantly effective in the swimmers. Also, due to its high amino acid content, BUN and creatinine levels tended to increase.Key words: Royal jelly, swimming, exercise, biochemical parameters, ergogenic aids

Electron transport in Ga-rich InxGa1-xN alloys

WOS: 000249810900060Resistivity and Hall effect measurements on n-type undoped Ga-rich InxGa1-xN (0.06 <= x <= 0.135) alloys grown by metal-organic vapour phase epitaxy (MOVPE) technique are carried out as a function of temperature (15-350K). Within the experimental error, the electron concentration in InxGa1-xN alloys is independent of temperature while the resistivity decreases as the temperature increases. Therefore, 1nxGai_x1V (0.06 <= x <= 0.135) alloys are considered in the metallic phase near the Mott transition. It has been shown that the temperature-dependent metallic conductivity can be well explained by the Mott model that takes into account electron-electron interactions and weak localization effects

Compact Measurement Station for Low Energy Proton Beams

A compact, remote controlled, cost efficient diagnostic station has been developed to measure the charge, the profile and the emittance for low energy proton beams. It has been installed and tested in the proton beam line of the Project Prometheus at SANAEM of the Turkish Atomic Energy Authority.Comment: 7 pages 2 column

Electronic transport characterization of AlGaN/GaN heterostructures using quantitative mobility spectrum analysis

Cataloged from PDF version of article.Resistivity and Hall effect measurements in nominally undoped Al0.25Ga0.75N/GaN heterostructures grown on sapphire substrate by metal-organic chemical vapor deposition are carried out as a function of temperature (20-350 K) and magnetic field (0-1.5 T). The measurement results are analyzed using the quantitative mobility spectrum analysis techniques. It is found that there is strong two-dimensional electron gas localization below 100 K, while the thermally activated minority carriers with the activation energies of similar to 58 and similar to 218 meV contribute to the electron transport at high temperatures. (C) 2007 American Institute of Physics

Pulsed Beam Tests at the SANAEM RFQ Beamline

A proton beamline consisting of an inductively coupled plasma (ICP) source, two solenoid magnets, two steerer magnets and a radio frequency quadrupole (RFQ) is developed at the Turkish Atomic Energy Authority's (TAEA) Saraykoy Nuclear Research and Training Center (SNRTC-SANAEM) in Ankara. In Q4 of 2016, the RFQ was installed in the beamline. The high power tests of the RF power supply and the RF transmission line were done successfully. The high power RF conditioning of the RFQ was performed recently. The 13.56 MHz ICP source was tested in two different conditions, CW and pulsed. The characterization of the proton beam was done with ACCTs, Faraday cups and a pepper-pot emittance meter. Beam transverse emittance was measured in between the two solenoids of the LEBT. The measured beam is then reconstructed at the entrance of the RFQ by using computer simulations to determine the optimum solenoid currents for acceptance matching of the beam. This paper will introduce the pulsed beam test results at the SANAEM RFQ beamline. In addition, the high power RF conditioning of the RFQ will be discussed.Comment: 6 pages, 6 figures. Proceedings of the International Particle Accelerator Conference 2017 (IPAC'17), May 14-19, 2017, TUPAB015, p. 134

Phytochemical and antioxidant characteristics of medlar fruits (Mespilus germanica L.)

Eleven medlar (Mespilus germanica L.) genotypes sampled from Turkey were analyzed for their fruit weight, fruit dimensions, fruit firmness, ostiole diameter, shape index, skin color, moisture (%), ash (%), reducing sugar (%), crude protein (%), pH, soluble solid content (%), vitamin C (mg/100 g), minerals (P, K, Ca, Mg, Fe, Zn, Mn), total phenolic content and total antioxidant capacity. A wide variation among genotypes on most of the searched parameters was evident. Fruit weight varied from 11.21 g to 33.24 g indicating high variability among genotypes. Determination of antioxidant activities by β-carotene–linoleic acid and 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assays resulted in average 80.8%, and 46.6 μg/ml FW DPPH, respectively. The total phenolic contents of eleven medlar genotypes varied from 114 to 293 mg gallic acid equivalent in 100 g fresh weight basis. The medlar fruits were found to be rich in terms of potassium, calcium, phosphorus, magnesium and iron

Water distribution in shocked regions of the NGC1333-IRAS4A protostellar outflow

We present the study of the H2O spatial distribution at two bright shocked regions along IRAS4A, one of the strongest H2O emitters among the Class 0 outflows. We obtained Herschel-PACS maps of the IRAS4A outflow and HIFI observations of two shocked positions. The largest HIFI beam of 38 arcsec at 557 GHz was mapped in several key water lines with different upper energy levels, to reveal possible spatial variations of the line profiles. We detect four H2O lines and CO (16-15) at the two selected positions. In addition, transitions from related outflow and envelope tracers are detected. Different gas components associated with the shock are identified in the H2O emission. In particular, at the head of the red lobe of the outflow, two distinct gas components with different excitation conditions are distinguished in the HIFI emission maps: a compact component, detected in the ground-state water lines, and a more extended one. Assuming that these two components correspond to two different temperature components observed in previous H2O and CO studies, the excitation analysis of the H2O emission suggests that the compact (about 3 arcsec) component is associated with a hot (T~1000 K) gas with densities ~(1-4)x10^5 cm^{-3}, whereas the extended one (10-17 arcsec) traces a warm (T~300-500 K) and dense gas (~(3-5)x10^7 cm^{-3}). Finally, using the CO (16-15) emission observed at R2, we estimate the H2O/H2 abundance of the warm and hot components to be (7-10)x10^{-7} and (3-7)x10^{-5}. Our data allowed us, for the first time, to resolve spatially the two temperature components previously observed with HIFI and PACS. We propose that the compact hot component may be associated with the jet that impacts the surrounding material, whereas the warm, dense, and extended component originates from the compression of the ambient gas by the propagating flow.Comment: 13 pages, 11 figures. Accepted for publication in Astronomy and Astrophysic