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Search Results: 1 - 10 of 409978 matches for " T. S. Ko "
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Modified Bean Seed Protein Phaseolin Did Not Accumulate Stably in Transgenic Tobacco Seeds after Methionine Enhancement Mutations  [PDF]
Eric Lasserre, T. S. Ko, John M. Dyer, Norimoto Murai
American Journal of Plant Sciences (AJPS) , 2015, DOI: 10.4236/ajps.2015.65069
Abstract: The major seed storage protein phaseolin of common bean (Phaseolus vulgaris L.) is deficient in methionine, an essential amino acid for human and animal health. To improve the nutritional quality of common bean, we designed methionine enhancement of phaseolin based on the three-dimensional structure of protein, de novo design principles and genetic information. Amino acid substitution and loop insertion were targeted to the interior and exterior, respectively, of the protein’s β-barrels. First, we introduced the methionine enhancement mutations into phaseolin cDNA, expressed cDNA in Escherichia coli and purified monomeric non-glycosylated proteins. Biophysical analysis of E. coli-expressed proteins demonstrated a similar structural stability of wild-type and mutant phaseolin monomers. Here, we attempted to test the structural stability of the methionine-enhanced phaseolin by introducing phaseolin cDNA to tobacco via Agrobacterium tumefaciens-mediated transformation of leaf disks, regenerating transgenic tobacco plants, and examining the accumulation of phaseolin protein in mature transgenic tobacco seeds. We used seven constructs containing different extents of methionine enhancement, ranging from the original 3 to maximum 33 methionines per 397 amino acid residues. ELISA analyses indicated that the methionine-enhanced phaseolins did not accumulate as stably in mature transgenic tobacco seeds as the wild-type phaseolin. It seems likely that the methionine-enhanced phaseolin proteins were under the stringent scrutiny of the protein quality control mechanism in the endoplasmic reticulum (ER), Golgi complex and/or vacuolar protein bodies. The protein degradation is probably to occur in the vacuolar protein bodies due to the instability of the trimer assembly caused by the methionine enhancement mutations targeting either amino-acids substitutions or/and loop insertions to the interior β-sheets and tum/loop regions, respectively, of N- and C-barrel structures.
Ultimate-state scaling in a shell model for homogeneous turbulent convection
Emily S. C. Ching,T. C. Ko
Physics , 2008, DOI: 10.1103/PhysRevE.78.036309
Abstract: An interesting question in turbulent convection is how the heat transport depends on the strength of thermal forcing in the limit of very large thermal forcing. Kraichnan predicted [Phys. Fluids {\bf 5}, 1374 (1962)] that the heat transport measured by the Nusselt number (Nu) would depend on the strength of thermal forcing measured by the Rayleigh number (Ra) as Nu $\sim$ Ra$^{1/2}$ with possible logarithmic corrections at very high Ra. This scaling behavior is taken as a signature of the so-called ultimate state of turbulent convection. The ultimate state was interpreted in the Grossmann-Lohse (GL) theory [J. Fluid Mech. {\bf 407}, 27 (2000)] as a bulk-dominated state in which both the kinetic and thermal dissipation are dominated by contributions from the bulk of the flow with the boundary layers either broken down or playing no role in the heat transport. In this paper, we study the dependence of Nu and the Reynolds number (Re) measuring the root-mean-squared velocity fluctuations on Ra and the Prandtl number (Pr) using a shell model for homogeneous turbulent convection where buoyancy is acting directly on most of the scales. We find that Nu$\sim$ Ra$^{1/2}$Pr$^{1/2}$ and Re$\sim$ Ra$^{1/2}$Pr$^{-1/2}$, which resemble the ultimate-state scaling behavior for fluids with moderate Pr, but the presence of a drag acting on the large scales is crucial in giving rise to such scaling. This suggests that if buoyancy acts on most of the scales in the bulk of turbulent convection at very high Ra, then the ultimate state cannot be a bulk-dominated state.
Photoinduced femtosecond relaxation of antiferromagnetic orders in the iron pnictides revealed by ultrafast laser ellipsometry
Patz A.,Li T.,Ran S.,Bud’ko S.
EPJ Web of Conferences , 2013, DOI: 10.1051/epjconf/20134103011
Abstract: We report ultrafast softening of the antiferromagnetic order, ~150fs after the electron thermalization, which follows a two-step recovery pathway to reveal a distinct interplay of magnetism and the nematic order in iron pnictides.
Acute cardiotoxic effects of high dose toluene: an experimental study
Ufuk Ta?,Fatih Ekici,Fatih Ko,Erkan S??üt
Anadolu Kardiyoloji Dergisi , 2013,
Abstract: Objective: This study aimed to investigate the acute cardiotoxic effects of high dose toluene and its damage mechanisms on heart tissue in the acute period.Methods: Twenty adult male Wistar Albino rats (200-220 g) were used in this controlled experimental animal study. Animals were divided into two equal groups: a control group (Group 1) and a high dose (6 mL/kg/gavage) toluene-administered group (Group 2). Arterial blood pressure (BP) and heart rate (HR) values were measured at 30th, 60th and 90th minutes after toluene was administered. At the end of the experimental period, blood samples and heart tissues were taken from the rats. Serum troponin T levels were assayed. Heart tissue sections were stained using routine histological methods and examined under a light microscope. In addition, the sections were immunohistochemically stained using the avidin-biotin-peroxidase method to determine caspase-3 immunoreactivity and TUNEL to detect apoptosis. To compare the apoptotic index, the Mann-Whitney U test was used. For comparisons between the two groups, the independent t- test was used. In addition, time-based changes of intra-group parameters were evaluated using paired t tests. Results: BP and HR values were low in toluene-treated rats compared to the control group. Troponin T levels were increased in toluene-administered animals as compared with controls [Toluene group: 0.140 (0.010-2.000) ng/mL vs control group: 0.010 (0.010-0.010) ng/mL, p=0.01]. Histopathologic examination of heart tissue sections showed congestion and edema in toluene administrated rats. Higher TUNEL positivity and (+++) immunoreactivity for caspase-3 protein were observed in the toluene group compared to the control group. Conclusion: The present study demonstrated that high doses of toluene cause apoptosis and may lead to impairment of cardiac function in the acute period.
Live Donor Partial Hepatectomy for Liver Transplantation: Is There a Learning Curve?
R. F. Saidi,N. Elias,D. S. Ko,T. Kawai
International Journal of Organ Transplantation Medicine , 2010,
Abstract: Background: Donor safety is the first priority in living donor liver transplantation (LDLT).Objective: To determine the characteristics and outcome of live liver donors who underwent donor hepatectomyfrom January, 1997 to May, 2007 at Massachusetts General Hospital.Methods: 30 patients underwent LDLT between January, 1997 and May, 2007 at our institution.Results: The type of graft was the right lobe (segments 5-8) in 14, left lobe (segments 2-4) in 4, and left lateralsector (segments 2 and 3) in 12 patients. The mean donor age was 36 (range: 26-57) years. The mean follow-up was 48 (range: 18-120) months. No deaths occurred. Overall, 8 (26.6%) patients experienced a total of 14 post-operative complications. Donor complications based on graft type were as follows: left lateralsector (16.7%), left lobe (25%), and right lobe (35.7%). The experience was divided into two periods 1997-2001 (n=15) and 2002-2007 (n=15). Overall complications during 2 periods were 40% and 13.3%, respectively (p<0.001). The incidence of grade III complication also significantly decreased; 66.7% vs 33.3% (p<0.01).Conclusion: Partial hepatectomy in living donors has a learning curve which appears to be approximately 15 cases. This learning curve is not restricted to the surgeons performing the procedure but involves all aspects of patient care.
Superconducting and Normal State Properties of Neutron Irradiated MgB2
R. H. T. Wilke,S. L. Bud'ko,P. C. Canfield,J. Famer,S. T. Hannahs
Physics , 2005, DOI: 10.1103/PhysRevB.73.134512
Abstract: We have performed a systematic study of the evolution of the superconducting and normal state properties of neutron irradiated MgB$_2$ wire segments as a function of fluence and post exposure annealing temperature and time. All fluences used suppressed the transition temperature, Tc, below 5 K and expanded the unit cell. For each annealing temperature Tc recovers with annealing time and the upper critical field, Hc2(T=0), approximately scales with Tc. By judicious choice of fluence, annealing temperature and time, the Tc of damaged MgB2 can be tuned to virtually any value between 5 and 39 K. For higher annealing temperatures and longer annealing times the recovery of Tc tends to coincide with a decrease in the normal state resistivity and a systematic recovery of the lattice parameters.
Effect of pressure on transport and magnetotransport properties in CaFe2As2 single crystals
M. S. Torikachvili,S. L. Bud'ko,N. Ni,P. C. Canfield,S. T. Hannahs
Physics , 2009,
Abstract: The effects of pressure generated in a liquid medium, clamp, pressure cell on the in-plane and c-axis resistance, temperature-dependent Hall coefficient and low temperature, magnetoresistance in CaFe2As2 are presented. The T - P phase diagram, including the observation of a complete superconducting transition in resistivity, delineated in earlier studies is found to be highly reproducible. The Hall resistivity and low temperature magnetoresistance are sensitive to different states/phases observed in CaFe2As2. Auxiliary measurements under uniaxial, c-axis, pressure are in general agreement with the liquid medium clamp cell results with some difference in critical pressure values and pressure derivatives. The data may be viewed as supporting the potential importance of non-hydrostatic components of pressure in inducing superconductivity in CaFe2As2.
Demographic growth and development of spa places in Serbia
?ur?ev Branislav S.,Ko?i? Kristina T.,Dragin Aleksandra S.
Glasnik Srpskog Geografskog Dru?tva , 2007, DOI: 10.2298/gsgd0701069d
Abstract: The paper deals with analysis of population growth and components of demographic growth in five most important spa settlements in Serbia: Vrnjacka banja, Niska banj, Banja Koviljaca. As indices of demographic development, we have analyzed: natural and mechanical movement of population, age and sex, activity and sex, households and apartments in spa places. The finding is that demographic development of spa places in Serbia has been politically influenced. Due to dismantling state territory of former Yugoslavia, the choice of domestic tourist destination for Serbian population became smaller. Because of that, spas became more important tourist destination which fostered demographic growth of those places. The data analysis demonstrated that during the last six decades, population in all spa places increased with higher insensitive compare with the rest of Serbia. This is the result of high inmigration, particularly in the last decade, when the share of this movement was over 90%. The pacing of population ageing in spa places, did not follow ageing of total population in Serbia. Average age in Serbia between 1961-2002. increased for 31.8%, while in spas population ageing was more intensify with 36.4% increase. The number of household showed constant increase from census to census, as well as in Serbia as in each of spa places with no exception. Average size of household in spas in 1948. was smaller than the average in Serbia for almost one member. By the year 2002. the average sizes of households in spas and in Serbia was almost equalized. Spa places suffered sortage of apartments in 1948. By the year 2002. the evidence showed considerable surplus which as the biggest in Vrnjacka Banja spa. The amount of surplus was 15%, which is higher than the average in Serbia. The purpose of this surplus is rent and accommodation of spa visitors. Overall results point out that despite of population decrease of Serbia, spa places enjoy more and more permanent residents. Among the reasons economic stability of spa places (in the areas of services and medical care) should be emphasized, which triggered inmigration increase, outmigration decrease, and slower rate of ageing (despite of small rate of natural increase).
Comet assay application for determining genotoxicity of veterinary vaccines preparations
Dybkova S. M.,Roman’ko M. E.,Gruzina T.G.,Rieznichenko L. S.
Biopolymers and Cell , 2010,
Abstract: Aim. To study a possibility of usage of the alkaline gel electrophoresis method (Comet assay) for determination of genotoxic properties of veterinary vaccines preparations. Methods. The alkaline gel electrophoresis of isolated eukaryotic cells has been used with further visualization of the samples by fluorescent microscopy. Results. Veterinary vaccines testing by the Comet assay method under alkaline conditions revealed that the samples No.1 and No 12 from twelve investigated vaccine preparations had genotoxic influence on eukaryotic cells of CHO-K1 and Vero test cultures, No. 12 sample being genotoxic only at metabolic activation. Conclusions. The method of alkaline gel lectrophoresis of single cells (Comet assay) is suitable for determination of veterinary vaccines genotoxic influence on the test eukaryotic cells CHO-K1. The method proposed in this paper is express, inexpensive and predictive. The accomplished experimental work allows us to recommend this method for characterization of biosafety of veterinary vaccines preparations.
Synthesis of Mg(B$_{1-x}$C$_x$)$_2$ Powders
R. H. T. Wilke,S. L. Bud'ko,P. C. Canfield,D. K. Finnemore,S. T. Hannahs
Physics , 2005, DOI: 10.1016/j.physc.2005.08.007
Abstract: We have synthesized bulk Mg(B$_{1-x}$C$_x$)$_2$ from a mixture of elemental Mg, B, and the binary compound B$_4$C. Carbon incorporation was dramatically improved by a two step reaction process at an elevated temperature of 1200 $^o$C. This reaction process results in a solubility limit near x$\sim$0.07. We found that impurities in the starting B cause an additive suppression of T$_c$. We combine these data with T$_c$ and H$_{c2}$(T=0) data from CVD wires as well as plasma spray synthesized powders and present a unifying H$_{c2}$ and T$_c$ versus x plot.
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