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Sample records for kas tuumaenergia akumulaatorid

  1. Molecular aspects of beta-ketoacyl synthase (KAS) catalysis.

    PubMed

    von Wettstein-Knowles, P; Olsen, J; Arnvig Mcguire, K; Larsen, S

    2000-12-01

    Crystal structure data for Escherichia coli beta-ketoacyl synthase (KAS) I with C(10) and C(12) fatty acid substrates bound in conjunction with results from mutagenizing residues in the active site leads to a model for catalysis. Differences from and similarities to the other Claisen enzymes carrying out decarboxylations reveal two catalytic mechanisms, one for KAS I and KAS II, the other for KAS III and chalcone synthase. A comparison of the structures of KAS I and KAS II does not reveal the basis of chain-length specificity. The structures of the Arabidopsis thaliana KAS family are compared.

  2. SRTM Anaglyph: Haro and Kas Hills

    NASA Technical Reports Server (NTRS)

    2001-01-01

    On January 26, 2001 the Kachchh region in western India suffered the most deadly earthquake in India's history. This three-dimensional view of landforms northeast of the city of Bhuj depicts geologic structures that are of interest in the study the tectonic processes that may have led to that earthquake. However, preliminary field studies indicate that these structures are composed of Mesozoic rocks that are overlain by younger rocks showing little deformation. Thus these structures may be old, not actively growing, and not directly related to the recent earthquake.

    The Haro Hills are on the left and the Kas Hills are on the right. The Haro Hills are an 'anticline,' which is an upwardly convex elongated fold of layered rocks. The anticline is distinctly ringed by an erosion resistant layer of sandstone. The east-west orientation of the anticline may relate to the crustal compression that has occurred during India's northward movement toward, and collision with, Asia. In contrast, the largest of the Kas Hills appears to be a tilted (to the south) and faulted (on the north) block of layered rocks. Also seen here, the curvilinear ridge trending toward the southwest from the image center is an erosion resistant 'dike,' which is an igneous intrusion into older 'host' rocks along a fault plane or other crack. The dike also appears to extend northeast from the image center as a dark line having very little topography. Its location between the tilted block and a smaller anticline to the north (directly east of the larger anticline) probably indicates that the dike fills the fault that separates these contrasting geologic structures. These features are simple examples of how digital elevation data can stereoscopically enhance satellite imagery to provide a direct input to geologic studies.

    The stereoscopic effect of this anaglyph was created by first draping a Landsat satellite image (taken just two weeks after the earthquake) over preliminary digital elevation

  3. SRTM Colored and Shaded Topography: Haro and Kas Hills, India

    NASA Image and Video Library

    2001-04-12

    On January 26, 2001, the Kachchh region in western India suffered the most deadly earthquake in India's history. This shaded topography view of landforms northeast of the city of Bhuj depicts geologic structures that are of interest in the study the tectonic processes that may have led to that earthquake. However, preliminary field studies indicate that these structures are composed of Mesozoic rocks that are overlain by younger rocks showing little deformation. Thus these structures may be old, not actively growing, and not directly related to the recent earthquake. The Haro Hills are on the left and the Kas Hills are on the right. The Haro Hills are an "anticline," which is an upwardly convex elongated fold of layered rocks. In this view, the anticline is distinctly ringed by an erosion resistant layer of sandstone. The east-west orientation of the anticline may relate to the crustal compression that has occurred during India's northward movement toward, and collision with, Asia. In contrast, the largest of the Kas Hills appears to be a tilted (to the south) and faulted (on the north) block of layered rocks. Also seen here, the linear feature trending toward the southwest from the image center is an erosion-resistant "dike," which is an igneous intrusion into older "host" rocks along a fault plane or other crack. These features are simple examples of how shaded topography can provide a direct input to geologic studies. In this image, colors show the elevation as measured by the Shuttle Radar Topography Mission (SRTM). Colors range from green at the lowest elevations, through yellow and red, to purple at the highest elevations. Elevations here range from near sea level to about 300 meters (about 1000 feet). Shading has been added, with illumination from the north (image top). http://photojournal.jpl.nasa.gov/catalog/PIA03300

  4. Identification of KasA as the cellular target of an anti-tubercular scaffold

    PubMed Central

    Abrahams, Katherine A.; Chung, Chun-wa; Ghidelli-Disse, Sonja; Rullas, Joaquín; Rebollo-López, María José; Gurcha, Sudagar S.; Cox, Jonathan A. G.; Mendoza, Alfonso; Jiménez-Navarro, Elena; Martínez-Martínez, María Santos; Neu, Margarete; Shillings, Anthony; Homes, Paul; Argyrou, Argyrides; Casanueva, Ruth; Loman, Nicholas J.; Moynihan, Patrick J.; Lelièvre, Joël; Selenski, Carolyn; Axtman, Matthew; Kremer, Laurent; Bantscheff, Marcus; Angulo-Barturen, Iñigo; Izquierdo, Mónica Cacho; Cammack, Nicholas C.; Drewes, Gerard; Ballell, Lluis; Barros, David; Besra, Gurdyal S.; Bates, Robert H.

    2016-01-01

    Phenotypic screens for bactericidal compounds are starting to yield promising hits against tuberculosis. In this regard, whole-genome sequencing of spontaneous resistant mutants generated against an indazole sulfonamide (GSK3011724A) identifies several specific single-nucleotide polymorphisms in the essential Mycobacterium tuberculosis β-ketoacyl synthase (kas) A gene. Here, this genomic-based target assignment is confirmed by biochemical assays, chemical proteomics and structural resolution of a KasA-GSK3011724A complex by X-ray crystallography. Finally, M. tuberculosis GSK3011724A-resistant mutants increase the in vitro minimum inhibitory concentration and the in vivo 99% effective dose in mice, establishing in vitro and in vivo target engagement. Surprisingly, the lack of target engagement of the related β-ketoacyl synthases (FabH and KasB) suggests a different mode of inhibition when compared with other Kas inhibitors of fatty acid biosynthesis in bacteria. These results clearly identify KasA as the biological target of GSK3011724A and validate this enzyme for further drug discovery efforts against tuberculosis. PMID:27581223

  5. Differential expression of fatty acid synthase genes, Acl, Fat and Kas, in Capsicum fruit.

    PubMed

    Aluru, Maneesha R; Mazourek, Michael; Landry, Laurie G; Curry, Jeanne; Jahn, Molly; O'Connell, Mary A

    2003-07-01

    The biosynthesis of capsaicinoids in the placenta of chilli fruit is modelled to require components of the fatty acid synthase (FAS) complex. Three candidate genes for subunits in this complex, Kas, Acl, and Fat, isolated based on differential expression, were characterized. Transcription of these three genes was placental-specific and RNA abundance was positively correlated with degree of pungency. Kas and Acl were mapped to linkage group 1 and Fat to linkage group 6. None of the genes is linked to the pungency locus, C, on linkage group 2. KAS accumulation was positively correlated with pungency. Western blots of placental extracts and histological sections both demonstrated that the accumulation of this enzyme was correlated with fruit pungency and KAS was immunolocalized to the expected cell layer, the placental epidermis. Enzyme activity of the recombinant form of the placental-specific KAS was confirmed using crude cell extracts. These FAS components are fruit-specific members of their respective gene families. These genes are predicted to be associated with Capsicum fruit traits, for example, capsaicinoid biosynthesis or fatty acid biosynthesis necessary for placental development.

  6. Theoretical estimation of the aqueous pKas of thiols

    NASA Astrophysics Data System (ADS)

    Hunter, Nora E.; Seybold, Paul G.

    2014-02-01

    The ionisation state of a compound is a key parameter influencing the compound's activity as a drug, metabolite, pollutant, or other active chemical agent. Sulfhydrol compounds (thiols) tend to be considerably more acidic than their hydroxyl (alcohol) analogues. In this report, quantum chemical approaches previously used for the estimation of the aqueous pKas of alcohols are applied to the estimation of the acidities of thiols. Acidity estimates obtained from the general-purpose SPARC calculational programme (S.H. Hilal, S.W. Karickhoff, and L.A. Carreira, Quant. Struct.-Act. Relat. 14, 348 (1995)) and the ACD/Labs PhysChem Suite v12 programme package are employed as benchmarks. Quantum chemical calculations were performed using both the semiempirical RM1 method and the density functional theory B3LYP/6-31+G* method. The effectiveness of the SM5.4 and SM8 solvent models in estimating the aqueous-phase acidities was also evaluated. All of the approaches examined demonstrated strong correlations with the experimental acidity values.

  7. SRTM Colored and Shaded Topography: Haro and Kas Hills, India

    NASA Technical Reports Server (NTRS)

    2001-01-01

    On January 26, 2001, the Kachchh region in western India suffered the most deadly earthquake in India's history. This shaded topography view of landforms northeast of the city of Bhuj depicts geologic structures that are of interest in the study the tectonic processes that may have led to that earthquake. However, preliminary field studies indicate that these structures are composed of Mesozoic rocks that are overlain by younger rocks showing little deformation. Thus these structures may be old, not actively growing, and not directly related to the recent earthquake.

    The Haro Hills are on the left and the Kas Hills are on the right. The Haro Hills are an 'anticline,' which is an upwardly convex elongated fold of layered rocks. In this view, the anticline is distinctly ringed by an erosion resistant layer of sandstone. The east-west orientation of the anticline may relate to the crustal compression that has occurred during India's northward movement toward, and collision with, Asia. In contrast, the largest of the Kas Hills appears to be a tilted (to the south) and faulted (on the north) block of layered rocks. Also seen here, the linear feature trending toward the southwest from the image center is an erosion-resistant 'dike,' which is an igneous intrusion into older 'host' rocks along a fault plane or other crack. These features are simple examples of how shaded topography can provide a direct input to geologic studies.

    In this image, colors show the elevation as measured by the Shuttle Radar Topography Mission (SRTM). Colors range from green at the lowest elevations, through yellow and red, to purple at the highest elevations. Elevations here range from near sea level to about 300 meters (about 1000 feet). Shading has been added, with illumination from the north (image top).

    Elevation data used in this image was acquired by the Shuttle Radar Topography Mission aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same

  8. The protonation state of catalytic residues in the resting state of KasA revisited: detailed mechanism for the activation of KasA by its own substrate.

    PubMed

    Lee, Wook; Engels, Bernd

    2014-02-11

    Mycobacterium tuberculosis is the causative pathogen of tuberculosis, the second leading cause of death from an infectious disease globally. β-Ketoacyl ACP synthase I (KasA) is essential for the survival of M. tuberculosis, because it is one of the key enzymes in the biosynthetic pathway of mycolic acid, the building block of the cell wall in M. tuberculosis. To distinguish among the various suggested mechanisms of KasA that are based on different protonation states of the active site, we characterize its resting state by various theoretical approaches ranging from first-principle-based quantum mechanical/molecular mechanical molecular dynamics simulations (QM/MM MD) with large QM parts to force field-based MD and free energy perturbation computations. In contrast to a previous study that used less reliable semiempirical approaches in combination with smaller QM parts, our improved computations predict that the most important active site residues, Cys171 and His311, are neutral. Because the neutral catalytic residues are too unreactive to attack the substrate, the question of how their activation is achieved arises. Combining our computed results with structural information about the malonyl binding pocket, we devised a detailed model about the activation mechanism. A conformational change of Phe404 possibly triggered by the substrate is central for the activation because it switches KasA to the sufficiently reactive zwitterionic state.

  9. Electrostatic Environment of Hemes in Proteins: pKas of Hydroxyl Ligands†

    PubMed Central

    Song, Yifan; Mao, Junjun; Gunner, M. R.

    2009-01-01

    The pKas of ferric aquo–heme and aquo–heme electrochemical midpoints (Ems) at pH 7 in sperm whale myoglobin, Aplysia myoblogin, hemoglobin I, heme oxygenase 1, horseradish peroxidase and cytochrome c oxidase were calculated with Multi-Conformation Continuum Electrostatics (MCCE). The pKas span 3.3 pH units from 7.6 in heme oxygenase 1 to 10.9 in peroxidase, and the Ems range from −250 mv in peroxidase to 125 mV in Aplysia myoglobin. Proteins with higher in situ ferric aquo–heme pKas tend to have lower Ems. Both changes arise from the protein stabilizing a positively charged heme. However, compared with values in solution, the protein shifts the aquo–heme Ems more than the pKas. Thus, the protein has a larger effective dielectric constant for the protonation reaction, showing that electron and proton transfers are coupled to different conformational changes that are captured in the MCCE analysis. The calculations reveal a breakdown in the classical continuum electrostatic analysis of pairwise interactions. Comparisons with DFT calculations show that Coulomb’s law overestimates the large unfavorable interactions between the ferric water–heme and positively charged groups facing the heme plane by as much as 60%. If interactions with CuB in cytochrome c oxidase and Arg 38 in horseradish peroxidase are not corrected, the pKa calculations are in error by as much as 6 pH units. With DFT corrected interactions calculated pKas and Ems differ from measured values by less than 1 pH unit or 35 mV, respectively. The in situ aquo–heme pKa is important for the function of cytochrome c oxidase since it helps to control the stoichiometry of proton uptake coupled to electron transfer PMID:16800621

  10. SRTM Stereo Pair: Haro and Kas Hills, India

    NASA Technical Reports Server (NTRS)

    2001-01-01

    On January 26, 2001 the Kachchh region in western India suffered the most deadly earthquake in India's history. This stereoscopic view of landforms northeast of the city of Bhuj depicts geologic structures that are of interest in the study the tectonic processes that may have led to that earthquake. However, preliminary field studies indicate that these structures are composed of Mesozoic rocks that are overlain by younger rocks showing little deformation. Thus these structures may be old, not actively growing, and not directly related to the recent earthquake.

    The Haro Hills are on the left and the Kas Hills are on the right. The Haro Hills are an 'anticline,' which is an upwardly convex elongated fold of layered rocks. The anticline is distinctly ringed by an erosion resistant layer of sandstone. The east-west orientation of the anticline may relate to the crustal compression that has occurred during India's northward movement toward, and collision with, Asia. In contrast, the largest of the Kas Hills appears to be a tilted (to the south) and faulted (on the north) block of layered rocks. Also seen here, the curvilinear ridge trending toward the southwest from the image center is an erosion resistant 'dike,' which is an igneous intrusion into older 'host' rocks along a fault plane or other crack. The dike also appears to extend northeast from the image center as a dark line having very little topography. Its location between the tilted block and a smaller anticline to the north (directly east of the larger anticline) probably indicates that the dike fills the fault that separates these contrasting geologic structures. These features are simple examples of how digital elevation data can stereoscopically enhance satellite imagery to provide a direct input to geologic studies.

    This stereoscopic image was generated by draping a Landsat satellite image (taken just two weeks after the earthquake) over a preliminary Shuttle Radar Topography Mission (SRTM

  11. SRTM Stereo Pair: Haro and Kas Hills, India

    NASA Technical Reports Server (NTRS)

    2001-01-01

    On January 26, 2001 the Kachchh region in western India suffered the most deadly earthquake in India's history. This stereoscopic view of landforms northeast of the city of Bhuj depicts geologic structures that are of interest in the study the tectonic processes that may have led to that earthquake. However, preliminary field studies indicate that these structures are composed of Mesozoic rocks that are overlain by younger rocks showing little deformation. Thus these structures may be old, not actively growing, and not directly related to the recent earthquake.

    The Haro Hills are on the left and the Kas Hills are on the right. The Haro Hills are an 'anticline,' which is an upwardly convex elongated fold of layered rocks. The anticline is distinctly ringed by an erosion resistant layer of sandstone. The east-west orientation of the anticline may relate to the crustal compression that has occurred during India's northward movement toward, and collision with, Asia. In contrast, the largest of the Kas Hills appears to be a tilted (to the south) and faulted (on the north) block of layered rocks. Also seen here, the curvilinear ridge trending toward the southwest from the image center is an erosion resistant 'dike,' which is an igneous intrusion into older 'host' rocks along a fault plane or other crack. The dike also appears to extend northeast from the image center as a dark line having very little topography. Its location between the tilted block and a smaller anticline to the north (directly east of the larger anticline) probably indicates that the dike fills the fault that separates these contrasting geologic structures. These features are simple examples of how digital elevation data can stereoscopically enhance satellite imagery to provide a direct input to geologic studies.

    This stereoscopic image was generated by draping a Landsat satellite image (taken just two weeks after the earthquake) over a preliminary Shuttle Radar Topography Mission (SRTM

  12. Structural, electronic, and elastic properties of K-As compounds: a first principles study.

    PubMed

    Ozisik, Havva Bogaz; Colakoglu, Kemal; Deligoz, Engin; Ozisik, Haci

    2012-07-01

    First-principle calculations are performed to investigate the structural, elastic and electronic properties of K-As compounds (KAs in NaP, LiAs and AuCu-type structures, KAs(2) in MgCu(2)-type structure, K(3)As in Na(3)As, Cu(3)P and Li(3)Bi-type structures, and K(5)As(4) in A(5)B(4)-type structure). The lattice parameters, cohesive energy, formation energy, bulk modulus, and the first derivative of bulk modulus (to fit to the Murnaghan's equation of state) of the considered structures are calculated and reasonable agreement is obtained, and the phase transition pressure is also predicted. The repeated calculations on the electronic band structures and the related partial density of states are also given. The calculated second-order elastic constants based on the stress-strain method and the other related quantities such as Young's modulus, shear modulus, Poisson's ratio, sound velocities, Debye temperature, and shear anisotropy factors for considered structures are presented, and trends are discussed.

  13. Elucidation of the protonation states of the catalytic residues in mtKasA - Implications for inhibitor design

    PubMed Central

    Lee, Wook; Luckner, Sylvia R.; Kisker, Caroline; Tonge, Peter. J.; Engels, B.

    2015-01-01

    KasA (β-Ketoacyl ACP synthase I) is involved in the biosynthetic pathway of mycolic acids, an essential component of the cell wall in Mycobacterium tuberculosis. It was shown that KasA is essential for the survival of the pathogen and thus could serve as a new drug target to treat tuberculosis. The active site of KasA was previously characterized by X-ray crystallography. However, questions regarding the protonation state of specific amino acids, the orientation of the histidine groups within the active site, and additional conformers being accessible at ambient temperatures remain open and have to be addressed prior to the design of new inhibitors. We investigated the active site of KasA in the present work by means of structural motifs and relative energies. Molecular dynamics (MD) simulations, free energy perturbation (FEP) computations, and calculations employing the hybrid quantum mechanics/molecular mechanics (QM/MM) method made it possible to determine the protonation status and reveal important details about the catalytic mechanism of KasA. Additionally, we can rationalize the molecular basis for the acyl-transfer activity in the H311A mutant. Our data strongly suggest that inhibitors should be able to inhibit different protonation states because the enzyme can switch easily between a zwitterionic and neutral state. PMID:21615093

  14. New data on the structure of the Kas Block in the basement of the West Siberian Plate

    NASA Astrophysics Data System (ADS)

    Kheraskova, T. N.; Kaplan, S. A.; Bubnov, V. P.; Galuev, V. I.

    2013-03-01

    A new concept concerning the structure and stages of evolution of the Kas Block of the West Siberian Plate is stated in this paper. The Kas Block is traditionally considered to be a subsided western margin of the Siberian Platform. The new concept is based on the results of the interpretation of the geophysical data recently obtained along the reference and regional profiles in this territory. The geological interpretation of the deep dynamic sections obtained by reprocessing of the CDP seismic reflection records has been performed for the first time. The structural features of the Kas Block, as well as the character of its junction with the Siberian Platform and the Paleozoic framework, are discussed. The tectonic scheme of the territory and the scheme of the pre-Late Devonian surface of the Kas Block have been compiled. The Baikalian age of the basement of the Kas Block is substantiated. The Salairian allochthonous ophiolite-basalt tectonic nappe is localized for the first time within the sedimentary cover of the Kas Block. The available information allowed us to reconstruct the development of the western margin of the Siberian continent in the Riphean and Early Paleozoic before and after the Baikalian Orogeny, respectively. The informational background of the geological and geophysical interpretation involves the results of the CDP seismic reflection profiling, including the deep dynamic seismic sections and parameters of the P-wave velocities along the reference 1-SB seismic line and the regional Vostok 10, 12, 15, and 16 seismic lines; the results of the deep seismic and magnetotelluric soundings; the gravity measurements; the magnetic exploration; and the new coherent physical geological models.

  15. [A New Diagnostic Tool for Apraxia in Patients with Right-Hemisphere Stroke: The Revised Cologne Apraxia Screening (KAS-R)].

    PubMed

    Wirth, K; Held, A; Kalbe, E; Kessler, J; Saliger, J; Karbe, H; Fink, G R; Weiss, P H

    2016-10-01

    The Cologne Apraxia Screening (KAS) was developed to diagnose apraxia following left-hemisphere (LH) stroke. The present study aims at developing a diagnostic tool for patients with right-hemisphere (RH) stroke (KAS-R) by modifying the test material of the KAS and reducing the test items based on psychometric analyses.A total of 100 patients with RH stroke and 77 healthy control participants were tested. Psychometric analyses led to the exclusion of 8 KAS items. The final KAS-R, consisting of 12 items, shows good internal consistency (α = 0.795) as well as high sensitivity (79.4 %) and specificity (84.4 %). Applying a cut-off value of ≤ 46 (out of 48) points, 39 RH stroke patients were diagnosed with apraxia. Significant correlations were found between the KAS-R and an imitation test as well as expert ratings, indicating high construct validity. The results suggest that the KAS-R is a reliable and valid diagnostic tool for apraxic deficits after RH stroke. © Georg Thieme Verlag KG Stuttgart · New York.

  16. Site-directed mutagenesis of the toxin from the Chinese scorpion Buthus martensii Karsch (BmKAS): insight into sites related to analgesic activity.

    PubMed

    Cui, Yong; Song, Yong-Bo; Ma, Lin; Liu, Yan-Feng; Li, Guo-Dong; Wu, Chun-Fu; Zhang, Jing-Hai

    2010-10-01

    This study utilized the E. coli expression system to investigate the role of amino acid residues in toxin from the Chinese scorpion--Buthus martensii Karsch (BmKAS). To evaluate the extent to which residues of the toxin core contribute to its analgesic activity, ten mutants of BmKAS were obtained by PCR. Using site-directed mutagenesis, all of these residues were substituted with different amino acids. This study represents a thorough mapping and elucidation of the epitopes that form the molecular basis of the toxin's analgesic activity. Our results showed large mutant-dependent differences that emphasize the important roles of the studied residues.

  17. Molecular dynamics of Mycobacterium tuberculosis KasA: implications for inhibitor and substrate binding and consequences for drug design

    NASA Astrophysics Data System (ADS)

    Schaefer, Benjamin; Kisker, Caroline; Sotriffer, Christoph A.

    2011-11-01

    Inhibition of the production of fatty acids as essential components of the mycobacterial cell wall has been an established way of fighting tuberculosis for decades. However, increasing resistances and an outdated medical treatment call for the validation of new targets involved in this crucial pathway. In this regard, the β-ketoacyl ACP synthase KasA is a promising enzyme. In this study, three molecular dynamics simulations based on the wildtype crystal structures of inhibitor bound and unbound KasA were performed in order to investigate the flexibility and conformational space of this target. We present an exhaustive analysis of the binding-site flexibility and representative pocket conformations that may serve as new starting points for structure-based drug design. We also revealed a mechanism which may account for the comparatively low binding affinity of thiolactomycin. Furthermore, we examined the behavior of water molecules within the binding pocket and provide recommendations how to handle them in the drug design process. Finally, we analyzed the dynamics of a channel that accommodates the long-chain fatty acid substrates and, thereby, propose a mechanism of substrate access to this channel and how products are most likely released.

  18. Docking studies of flavonoid compounds as inhibitors of β-ketoacyl acyl carrier protein synthase I (Kas I) of Escherichia coli.

    PubMed

    Sabbagh, Ghalia; Berakdar, Noura

    2015-09-01

    Escherichia coli is one of the most frequent causes of many common bacterial infections, including cholecystitis, bacteremia, cholangitis, urinary tract infection (UTI), traveler's diarrhea and other clinical infections such as neonatal meningitis and pneumonia. The fatty acid biosynthesis is essential for the bacterial viability and growth. There are three types of β-ketoacyl acyl carrier protein synthase (KAS) which are important for overcoming the bacterial resistance problem. β-ketoacyl acyl carrier protein synthase I (KAS I) is member of the condensing enzyme family, which is a key catalyst in bacterial fatty acid biosynthesis, and thus an attractive target for novel antibioticsis related to the elongation of unsaturated fatty acids in bacterial fatty acid synthesis and can be a good therapeutic target of designing novel antibiotics. In this report, we performed docking study of E. coli (KAS I) and 50 flavonoids. Out of these 50 flavonoids, there are two compounds, genistein and isorhamnetin, that showed the superior binding energy while fully satisfying the conditions of drug likeliness. The predicted binding energy of genistein and isorhamnetin toward KAS I are -135.76kcal/mol and -132.42kcal/mol, respectively. These energies favorably compare to the biding energy of known drugs thiolactomicin and cerulenin that are -90.26kcal/mol and -99.64kcal/mol, respectively. The method used was docking with the selected E. coli (KAS I-PDB ID-1FJ4) using iGemdock. This was also found to obey the Lipinski's guidelines of five and to show the drug likeliness and bioavailability. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Standard redox potentials, pKas, and hydricities of inorganic complexes under electrochemical conditions and implications for CO2 reduction.

    PubMed

    Saravanan, K; Keith, J A

    2016-10-21

    We use computational chemistry to systematically study the thermodynamic stabilities of protonated and reduced intermediate states for Ru(2,2'-bipyridine)3, Ru(1,10-phenanthroline)3, and Ru(phen)2(pyrido[3',4':5,6] pyrazino[2,3-f][1,10]phenanthroline) in aqueous solutions. Following our previous studies of aromatic N-heterocycle molecules, we report pKas, standard redox potentials, and hydricities as well as computationally derived Pourbaix diagrams that show which states would be thermodynamically stable at different conditions of pH and applied potential. Locations of added electrons within ligands and complexes after reductions are also shown with electron density difference plots. As with other aromatic N-heterocycle molecules implicated in CO2 reduction, we find that several of the boundary lines from the Pourbaix diagrams are in close proximity to the thermodynamic redox potentials for CO2 electroreductions, making them thermodynamically appropriate for energetically efficient hydrogen shuttling.

  20. HLA compatibility assessment and management of highly sensitized patients under the new kidney allocation system (KAS): A 2016 status report from twelve HLA laboratories across the U.S.

    PubMed

    Kamoun, M; Phelan, D; Noreen, H; Marcus, N; Klingman, L; Gebel, H M

    2017-01-01

    Twelve HLA laboratories were surveyed to assess the methods and operational issues involved to define highly sensitized patients and to assess HLA compatibility under the new kidney allocation system (KAS) in the U.S. All laboratories used single antigen bead assays both pre- and post-KAS to define both broad and allele-specific HLA antibodies. The methods and threshold used to list HLA unacceptable antigens in UNet for virtual crossmatch (vXM) and the criteria used for determining HLA compatibility varied among laboratories. Laboratories reported several limitations of the current assays including the accuracy of quantifiable antibody fluorescence values, inadequate coverage of common alleles on the bead panels, and challenges in calibrating the vXM. The new KAS has resulted in a significant surge of deceased donor organ offers requiring vXM evaluation under tight time constraints. In the post-KAS period, eight of twelve laboratories (67%) indicated that their center did not proceed to transplant based on vXM without a prospective lymphocyte crossmatch. In conclusion, HLA laboratories play a critical role in deceased donor allocation for highly sensitized patients under the new KAS. Significant opportunities exist to improve the methods used in the assessment of HLA compatibility to safely transplant highly sensitized patients. Copyright © 2016 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.

  1. pH-Dependent Conformational Changes in Proteins and Their Effect on Experimental pKas: The Case of Nitrophorin 4

    PubMed Central

    Di Russo, Natali V.; Estrin, Dario A.; Martí, Marcelo A.; Roitberg, Adrian E.

    2012-01-01

    The acid-base behavior of amino acids is an important subject of study due to their prominent role in enzyme catalysis, substrate binding and protein structure. Due to interactions with the protein environment, their pKas can be shifted from their solution values and, if a protein has two stable conformations, it is possible for a residue to have different “microscopic”, conformation-dependent pKa values. In those cases, interpretation of experimental measurements of the pKa is complicated by the coupling between pH, protonation state and protein conformation. We explored these issues using Nitrophorin 4 (NP4), a protein that releases NO in a pH sensitive manner. At pH 5.5 NP4 is in a closed conformation where NO is tightly bound, while at pH 7.5 Asp30 becomes deprotonated, causing the conformation to change to an open state from which NO can easily escape. Using constant pH molecular dynamics we found two distinct microscopic Asp30 pKas: 8.5 in the closed structure and 4.3 in the open structure. Using a four-state model, we then related the obtained microscopic values to the experimentally observed “apparent” pKa, obtaining a value of 6.5, in excellent agreement with experimental data. This value must be interpreted as the pH at which the closed to open population transition takes place. More generally, our results show that it is possible to relate microscopic structure dependent pKa values to experimentally observed ensemble dependent apparent pKas and that the insight gained in the relatively simple case of NP4 can be useful in several more complex cases involving a pH dependent transition, of great biochemical interest. PMID:23133364

  2. Effect of Ayurveda Medications (Kasīsa Bhasma and Dhātrī Avaleha) on Iron Deficiency Anaemia: A Randomized Controlled Study.

    PubMed

    Tubaki, Basavaraj Ramappa; Benni, Jyoti Mahadev; Rao, Niranjan; Prasad, Uchangi Nagaraja Rao

    2016-01-01

    This paper explores the role that Ayurveda can play in the management of Iron Deficiency Anaemia, a major nutritional deficiency disorder affecting people across the globe. Forty (40) patients suffering from Iron deficiency anaemia as per WHO guidelines, between the age group of 20 to 60 yrs of either sex participated in the study. Study was a randomized, controlled, open label clinical study. Patients were randomly divided into two groups: Group D (n = 20) received Dhārī avaleha 10 g twice a day after food. Group K (n = 20) received capsules Kasīsa bhasma 125 mg thrice a day. Both interventions were administered for 30 days and the subjects were followed up for next 30 days with placebo capsules to assess the sustainability of the effects. Assessments were done at baseline, 30(th) and 60(th) days. Primary outcome measure was hemoglobin estimation (Hb) and secondary outcome measures were the other hematological parameters such as Red blood cell (RBC) indices, total RBC count, Packed Cell volume (PCV) and Peripheral Blood smear study. Both interventions produced significant improvements (P < 0.001). Kasīsa bhasma was better compared to dhātrī avaleha in terms of primary (P < 0.0001) and secondary outcomes. Comparison of outcomes from base line - 30(th) day, base line - 60(th) day and 30(th) - 60(th) day showed significant (P < 0.0001) improvement in both the groups in parameters such as haemoglobin, MCV and MCH. Hence improvements sustained during placebo intervened sustainability period also. Study effectively shows that Kasīsa bhasma is better then Dhātrī avaleha. Improvements by both interventions were sustained even during the sustainability period.

  3. Effect of Ayurveda Medications (Kasīsa Bhasma and Dhātrī Avaleha) on Iron Deficiency Anaemia: A Randomized Controlled Study

    PubMed Central

    Tubaki, Basavaraj Ramappa; Benni, Jyoti Mahadev; Rao, Niranjan; Prasad, Uchangi Nagaraja Rao

    2016-01-01

    Background: This paper explores the role that Ayurveda can play in the management of Iron Deficiency Anaemia, a major nutritional deficiency disorder affecting people across the globe. Methodology: Forty (40) patients suffering from Iron deficiency anaemia as per WHO guidelines, between the age group of 20 to 60 yrs of either sex participated in the study. Study was a randomized, controlled, open label clinical study. Patients were randomly divided into two groups: Group D (n = 20) received Dhārī avaleha 10 g twice a day after food. Group K (n = 20) received capsules Kasīsa bhasma 125 mg thrice a day. Both interventions were administered for 30 days and the subjects were followed up for next 30 days with placebo capsules to assess the sustainability of the effects. Assessments were done at baseline, 30th and 60th days. Primary outcome measure was hemoglobin estimation (Hb) and secondary outcome measures were the other hematological parameters such as Red blood cell (RBC) indices, total RBC count, Packed Cell volume (PCV) and Peripheral Blood smear study. Results: Both interventions produced significant improvements (P < 0.001). Kasīsa bhasma was better compared to dhātrī avaleha in terms of primary (P < 0.0001) and secondary outcomes. Comparison of outcomes from base line – 30th day, base line – 60th day and 30th – 60th day showed significant (P < 0.0001) improvement in both the groups in parameters such as haemoglobin, MCV and MCH. Hence improvements sustained during placebo intervened sustainability period also. Conclusions: Study effectively shows that Kasīsa bhasma is better then Dhātrī avaleha. Improvements by both interventions were sustained even during the sustainability period. PMID:28182020

  4. Virus-induced silencing of Comt, pAmt and Kas genes results in a reduction of capsaicinoid accumulation in chili pepper fruits.

    PubMed

    del Rosario Abraham-Juárez, Ma; del Carmen Rocha-Granados, Ma; López, Mercedes G; Rivera-Bustamante, Rafael Francisco; Ochoa-Alejo, Neftalí

    2008-02-01

    Capsaicinoids are responsible for the pungent taste of chili pepper fruits of Capsicum species. Capsaicinoids are biosynthesized through both the phenylpropanoid and the branched-fatty acids pathways. Fragments of Comt (encoding a caffeic acid O-methyltransferase), pAmt (a putative aminotransferase), and Kas (a beta-keto-acyl-[acyl-carrier-protein] synthase) genes, that are differentially expressed in placenta tissue of pungent chili pepper, were individually inserted into a Pepper huasteco yellow veins virus (PHYVV)-derived vector to determine, by virus-induced gene silencing, irrespective of whether these genes are involved in the biosynthesis of capsaicinoids. Reduction of the respective mRNA levels as well as the presence of related siRNAs confirmed the silencing of these three genes. Morphological alterations were evident in plants inoculated with PHYVV::Comt and PHYVV::Kas constructs; however, plants inoculated with PHYVV::pAmt showed no evident alterations. On the other hand, fruit setting was normal in all cases. Biochemical analysis of placenta tissues showed that, indeed, independent silencing of all three genes led to a dramatic reduction in capsaicinoid content in the fruits demonstrating the participation of these genes in capsaicinoid biosynthesis. Using this approach it was possible to generate non-pungent chili peppers at high efficiency.

  5. Thiolactomycin-based β-ketoacyl-AcpM synthase A (KasA) inhibitors: fragment-based inhibitor discovery using transient one-dimensional nuclear overhauser effect NMR spectroscopy.

    PubMed

    Kapilashrami, Kanishk; Bommineni, Gopal R; Machutta, Carl A; Kim, Pilho; Lai, Cheng-Tsung; Simmerling, Carlos; Picart, Francis; Tonge, Peter J

    2013-03-01

    Thiolactomycin (TLM) is a natural product inhibitor of KasA, the β-ketoacyl synthase A from Mycobacterium tuberculosis. To improve the affinity of TLM for KasA, a series of TLM analogs have been synthesized based on interligand NOEs between TLM and a pantetheine analog when both are bound simultaneously to the enzyme. Kinetic binding data reveal that position 3 of the thiolactone ring is a suitable position for elaboration of the TLM scaffold, and the structure-activity relationship studies provide information on the molecular features that govern time-dependent inhibition in this enzyme system. These experiments also exemplify the utility of transient one-dimensional NOE spectroscopy for obtaining interligand NOEs compared with traditional steady state two-dimensional NOESY spectroscopy.

  6. Development of Solar Powered Feeding Scheme for Wireless Sensor Networks in low Solar Density Conditions / Bezvadu Sensoru Tīklu Elektroapgādes Sistēmas Izstrāde, Kas Izmanto Saules Paneļus Un Darbojas Pazeminātas Saules Radiācijas Apstākļos

    NASA Astrophysics Data System (ADS)

    Kondratjevs, K.; Zabasta, A.; Selmanovs-Pless, V.

    2015-08-01

    In the recent years, there has been significant research focus on the safety and reliability of data harvesting and optimal energy consuming by wireless sensor network nodes. If external electrical power fails, the node needs to be able to send notifications to the utility demanding the use of backup energy strategies. The authors of the research offer an approach that can help to use PV panels as an alternative power source for WSN nodes in particular irradiation conditions. Survey and testing of the main types of PV panels offered on the market in conditions closed to real ones, in which WSN nodes are maintained, have been implemented. Based on the test results, maximum power control module parameters can be calculated in order to achieve the best effectiveness of the power control system for a selected type of PV panel or panel group. The novelty of the research is an approach that includes an original test bed design for PV testing, PV testing method and selection of design and MPP control module parameters, which ensure maximum effectiveness of WSN node power feeding. Pēdējos gados vairāki pētījumi ir veltīti problēmām, kas ir saistītas ar enerģijas patēriņa mazināšanu un efektīvu izmantošanu bezvadu sensoru tīklu mezglos. Kad sensors mezgls ir izsmēlis enerģijas krājumu, tas vairs nefunkcionē un atslēdzas no kopēja tīkla, kas var būtiski ietekmēt visa tīkla veiktspēju. Šī pētījuma mērķis ir izveidot barošanas vadības moduli, lai nodrošinātu stabilu elektroapgādes spriegumu autonomi strādājošiem radio signāla atkārtotājiem, sensoriem vai vārtejām, kas darbojas bezvadu sensoru tīklos. Pētījuma ietvaros izstrādāta metode saules paneļu kvalitatīvai salīdzināšanai starp tehnoloģijām vai savā starpā, izvērtējot to atbilstību mērķa pielietojumam. Izstrādātā metode sniedz iespēju veikt kontrolētus testus pie variējošiem, simulētiem gaismas apstākļiem, ļauj prognozēt enerģijas resursus

  7. Distributed Database Kriging for Adaptive Sampling (D2 KAS)

    NASA Astrophysics Data System (ADS)

    Roehm, Dominic; Pavel, Robert S.; Barros, Kipton; Rouet-Leduc, Bertrand; McPherson, Allen L.; Germann, Timothy C.; Junghans, Christoph

    2015-07-01

    We present an adaptive sampling method supplemented by a distributed database and a prediction method for multiscale simulations using the Heterogeneous Multiscale Method. A finite-volume scheme integrates the macro-scale conservation laws for elastodynamics, which are closed by momentum and energy fluxes evaluated at the micro-scale. In the original approach, molecular dynamics (MD) simulations are launched for every macro-scale volume element. Our adaptive sampling scheme replaces a large fraction of costly micro-scale MD simulations with fast table lookup and prediction. The cloud database Redis provides the plain table lookup, and with locality aware hashing we gather input data for our prediction scheme. For the latter we use kriging, which estimates an unknown value and its uncertainty (error) at a specific location in parameter space by using weighted averages of the neighboring points. We find that our adaptive scheme significantly improves simulation performance by a factor of 2.5-25, while retaining high accuracy for various choices of the algorithm parameters.

  8. Distributed database kriging for adaptive sampling (D²KAS)

    DOE PAGES

    Roehm, Dominic; Pavel, Robert S.; Barros, Kipton; ...

    2015-03-18

    We present an adaptive sampling method supplemented by a distributed database and a prediction method for multiscale simulations using the Heterogeneous Multiscale Method. A finite-volume scheme integrates the macro-scale conservation laws for elastodynamics, which are closed by momentum and energy fluxes evaluated at the micro-scale. In the original approach, molecular dynamics (MD) simulations are launched for every macro-scale volume element. Our adaptive sampling scheme replaces a large fraction of costly micro-scale MD simulations with fast table lookup and prediction. The cloud database Redis provides the plain table lookup, and with locality aware hashing we gather input data for our predictionmore » scheme. For the latter we use kriging, which estimates an unknown value and its uncertainty (error) at a specific location in parameter space by using weighted averages of the neighboring points. We find that our adaptive scheme significantly improves simulation performance by a factor of 2.5 to 25, while retaining high accuracy for various choices of the algorithm parameters.« less

  9. Materials Data on KAs (SG:19) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-07-09

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  10. Distributed database kriging for adaptive sampling (D²KAS)

    SciTech Connect

    Roehm, Dominic; Pavel, Robert S.; Barros, Kipton; Rouet-Leduc, Bertrand; McPherson, Allen L.; Germann, Timothy C.; Junghans, Christoph

    2015-03-18

    We present an adaptive sampling method supplemented by a distributed database and a prediction method for multiscale simulations using the Heterogeneous Multiscale Method. A finite-volume scheme integrates the macro-scale conservation laws for elastodynamics, which are closed by momentum and energy fluxes evaluated at the micro-scale. In the original approach, molecular dynamics (MD) simulations are launched for every macro-scale volume element. Our adaptive sampling scheme replaces a large fraction of costly micro-scale MD simulations with fast table lookup and prediction. The cloud database Redis provides the plain table lookup, and with locality aware hashing we gather input data for our prediction scheme. For the latter we use kriging, which estimates an unknown value and its uncertainty (error) at a specific location in parameter space by using weighted averages of the neighboring points. We find that our adaptive scheme significantly improves simulation performance by a factor of 2.5 to 25, while retaining high accuracy for various choices of the algorithm parameters.

  11. Materials Data on KAsOF4 (SG:14) by Materials Project

    SciTech Connect

    Kristin Persson

    2016-02-04

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  12. Continuum Electrostatics Approaches to Calculating pKas and Ems in Proteins

    SciTech Connect

    Gunner, Marilyn R.; Baker, Nathan A.

    2016-06-20

    Proteins change their charge state through protonation and redox reactions as well as through binding charged ligands. The free energy of these reactions are dominated by solvation and electrostatic energies and modulated by protein conformational relaxation in response to the ionization state changes. Although computational methods for calculating these interactions can provide very powerful tools for predicting protein charge states, they include several critical approximations of which users should be aware. This chapter discusses the strengths, weaknesses, and approximations of popular computational methods for predicting charge states and understanding their underlying electrostatic interactions. The goal of this chapter is to inform users about applications and potential caveats of these methods as well as outline directions for future theoretical and computational research.

  13. Computational prediction of the pKas of small peptides through Conceptual DFT descriptors

    NASA Astrophysics Data System (ADS)

    Frau, Juan; Hernández-Haro, Noemí; Glossman-Mitnik, Daniel

    2017-03-01

    The experimental pKa of a group of simple amines have been plotted against several Conceptual DFT descriptors calculated by means of different density functionals, basis sets and solvation schemes. It was found that the best fits are those that relate the pKa of the amines with the global hardness η through the MN12SX density functional in connection with the Def2TZVP basis set and the SMD solvation model, using water as a solvent. The parameterized equation resulting from the linear regression analysis has then been used for the prediction of the pKa of small peptides of interest in the study of diabetes and Alzheimer disease. The accuracy of the results is relatively good, with a MAD of 0.36 units of pKa.

  14. Searching for Computational Strategies to Accurately Predict pKas of Large Phenolic Derivatives.

    PubMed

    Rebollar-Zepeda, Aida Mariana; Campos-Hernández, Tania; Ramírez-Silva, María Teresa; Rojas-Hernández, Alberto; Galano, Annia

    2011-08-09

    Twenty-two reaction schemes have been tested, within the cluster-continuum model including up to seven explicit water molecules. They have been used in conjunction with nine different methods, within the density functional theory and with second-order Møller-Plesset. The quality of the pKa predictions was found to be strongly dependent on the chosen scheme, while only moderately influenced by the method of calculation. We recommend the E1 reaction scheme [HA + OH(-) (3H2O) ↔ A(-) (H2O) + 3H2O], since it yields mean unsigned errors (MUE) lower than 1 unit of pKa for most of the tested functionals. The best pKa values obtained from this reaction scheme are those involving calculations with PBE0 (MUE = 0.77), TPSS (MUE = 0.82), BHandHLYP (MUE = 0.82), and B3LYP (MUE = 0.86) functionals. This scheme has the additional advantage, compared to the proton exchange method, which also gives very small values of MUE, of being experiment independent. It should be kept in mind, however, that these recommendations are valid within the cluster-continuum model, using the polarizable continuum model in conjunction with the united atom Hartree-Fock cavity and the strategy based on thermodynamic cycles. Changes in any of these aspects of the used methodology may lead to different outcomes.

  15. MCCE analysis of the pKas of introduced buried acids and bases in staphylococcal nuclease.

    PubMed

    Gunner, M R; Zhu, Xuyu; Klein, Max C

    2011-12-01

    The pK(a)s of 96 acids and bases introduced into buried sites in the staphylococcal nuclease protein (SNase) were calculated using the multiconformation continuum electrostatics (MCCE) program and the results compared with experimental values. The pK(a)s are obtained by Monte Carlo sampling of coupled side chain protonation and position as a function of pH. The dependence of the results on the protein dielectric constant (ε(prot)) in the continuum electrostatics analysis and on the Lennard-Jones non-electrostatics parameters was evaluated. The pK(a)s of the introduced residues have a clear dependence on ε(prot,) whereas native ionizable residues do not. The native residues have electrostatic interactions with other residues in the protein favoring ionization, which are larger than the desolvation penalty favoring the neutral state. Increasing ε(prot) scales both terms, which for these residues leads to small changes in pK(a). The introduced residues have a larger desolvation penalty and negligible interactions with residues in the protein. For these residues, changing ε(prot) has a large influence on the calculated pK(a). An ε(prot) of 8-10 and a Lennard-Jones scaling of 0.25 is best here. The X-ray crystal structures of the mutated proteins are found to provide somewhat better results than calculations carried out on mutations made in silico. Initial relaxation of the in silico mutations by Gromacs and extensive side chain rotamer sampling within MCCE can significantly improve the match with experiment. Copyright © 2011 Wiley-Liss, Inc.

  16. AIRID: an application of the KAS/Prospector expert system builder to airplane identification

    SciTech Connect

    Aldridge, J.P.

    1984-01-01

    The Knowledge Acquisition System/Prospector expert system building tool developed by SRI, International, has been used to construct an expert system to identify aircraft on the basis of observables such as wing shape, engine number/location, fuselage shape, and tail assembly shape. Additional detailed features are allowed to influence the identification as other favorable features. Constraints on the observations imposed by bad weather and distant observations have been included as contexts to the models. Models for Soviet and US fighter aircraft have been included. Inclusion of other types of aircraft such as bombers, transports, and reconnaissance craft is straightforward. Two models permit exploration of the interaction of semantic and taxonomic networks with the models. A full set of text data for fluid communication with the user has been included. The use of demons as triggered output responses to enhance utility to the user has been explored. This paper presents discussion of the ease of building the expert system using this powerful tool and problems encountered in the construction process.

  17. Continuum Electrostatics Approaches to Calculating pKas and Ems in Proteins.

    PubMed

    Gunner, M R; Baker, N A

    2016-01-01

    Proteins change their charge state through protonation and redox reactions as well as through binding charged ligands. The free energy of these reactions is dominated by solvation and electrostatic energies and modulated by protein conformational relaxation in response to the ionization state changes. Although computational methods for calculating these interactions can provide very powerful tools for predicting protein charge states, they include several critical approximations of which users should be aware. This chapter discusses the strengths, weaknesses, and approximations of popular computational methods for predicting charge states and understanding the underlying electrostatic interactions. The goal of this chapter is to inform users about applications and potential caveats of these methods as well as outline directions for future theoretical and computational research. © 2016 Elsevier Inc. All rights reserved.

  18. Identification and engineering of regulation-related genes toward improved kasugamycin production.

    PubMed

    Zhu, Chenchen; Kang, Qianjin; Bai, Linquan; Cheng, Lin; Deng, Zixin

    2016-02-01

    Kasugamycin, produced by Streptomyces kasugaensis and Streptomyces microaureus, is an important amino-glycoside family antibiotic and widely used for veterinary and agricultural applications. In the left flanking region of the previously reported kasugamycin gene cluster, four additional genes (two-component system kasW and kasX, MerR-family kasV, and isoprenylcysteine carboxyl methyltransferase kasS) were identified both in the low-yielding S. kasugaensis BCRC12349 and high-yielding S. microaureus XM301. Deletion of regulatory gene kasT abolished kasugamycin production, and its overexpression in BCRC12349 resulted in an increased titer by 186 %. Deletion of kasW, kasX, kasV, and kasS improved kasugamycin production by 12, 19, 194, and 22 %, respectively. qRT-PCR analysis demonstrated that the transcription of kas genes was significantly increased in all the four mutants. Similar gene inactivation was performed in the high-yielding strain S. microaureus XM301. As expected, the deletion of kasW/X resulted in a 58 % increase of the yield from 6 to 9.5 g/L. However, the deletion of kasV and over-expression of kasT had no obvious effect, and the disruption of kasS surprisingly decreased kasugamycin production. In addition, trans-complementation of the kasS mutant with a TTA codon-mutated kasS increased the kasugamycin yield by 20 %. A much higher transcription of kas genes was detected in the high-yielding XM301 than in the low-yielding BCRC12349, which may partially account for the discrepancy of gene inactivation effects between them. Our work not only generated engineered strains with improved kasugamycin yield, but also pointed out that different strategies on manipulating regulatory-related genes should be considered for low-yielding or high-yielding strains.

  19. High-Tc Nodeless s±-wave Superconductivity in (Y,La)FeAsO1-y with Tc=50K:As75-NMR Study

    NASA Astrophysics Data System (ADS)

    Mukuda, H.; Furukawa, S.; Kinouchi, H.; Yashima, M.; Kitaoka, Y.; Shirage, P. M.; Eisaki, H.; Iyo, A.

    2012-10-01

    We report on an As75-NMR study on the Fe-pnictide high-Tc superconductor Y0.95La0.05FeAsO1-y (Y0.95La0.051111) with Tc=50K that includes no magnetic rare-earth elements. The measurement of the nuclear-spin lattice-relaxation rate (751/T1) has revealed that the nodeless bulk superconductivity takes place at Tc=50K while antiferromagnetic spin fluctuations develop moderately in the normal state. These features are consistently described by the multiple fully gapped s±-wave model based on the Fermi-surface nesting. Incorporating the theory based on band calculations, we propose that the reason that Tc=50K in Y0.95La0.051111 is larger than Tc=28K in La1111 is that the Fermi-surface multiplicity is maximized, and hence the Fermi-surface nesting condition is better than that in La1111.

  20. Genetic enhancement of palmitic acid accumulation in cotton seed oil through RNAi down-regulation of ghKAS2 encoding β-ketoacyl-ACP synthase II (KASII).

    PubMed

    Liu, Qing; Wu, Man; Zhang, Baolong; Shrestha, Pushkar; Petrie, James; Green, Allan G; Singh, Surinder P

    2017-01-01

    Palmitic acid (C16:0) already makes up approximately 25% of the total fatty acids in the conventional cotton seed oil. However, further enhancements in palmitic acid content at the expense of the predominant unsaturated fatty acids would provide increased oxidative stability of cotton seed oil and also impart the high melting point required for making margarine, shortening and confectionary products free of trans fatty acids. Seed-specific RNAi-mediated down-regulation of β-ketoacyl-ACP synthase II (KASII) catalysing the elongation of palmitoyl-ACP to stearoyl-ACP has succeeded in dramatically increasing the C16 fatty acid content of cotton seed oil to well beyond its natural limits, reaching up to 65% of total fatty acids. The elevated C16 levels were comprised of predominantly palmitic acid (C16:0, 51%) and to a lesser extent palmitoleic acid (C16:1, 11%) and hexadecadienoic acid (C16:2, 3%), and were stably inherited. Despite of the dramatic alteration of fatty acid composition and a slight yet significant reduction in oil content in these high-palmitic (HP) lines, seed germination remained unaffected. Regiochemical analysis of triacylglycerols (TAG) showed that the increased levels of palmitic acid mainly occurred at the outer positions, while C16:1 and C16:2 were predominantly found in the sn-2 position in both TAG and phosphatidylcholine. Crossing the HP line with previously created high-oleic (HO) and high-stearic (HS) genotypes demonstrated that HP and HO traits could be achieved simultaneously; however, elevation of stearic acid was hindered in the presence of high level of palmitic acid.

  1. Increased access to transplantation of highly sensitized patients under the new kidney allocation system. A single center experience.

    PubMed

    Colovai, Adriana I; Ajaimy, Maria; Kamal, Layla G; Masiakos, Peter; Chan, Shirley; Savchik, Christina; Lubetzky, Michelle; de Boccardo, Graciela; Courson, Alesa; Chokechanachaisakul, Attasit; Graham, Jay; Greenstein, Stuart; Kinkhabwala, Milan; Rocca, Juan; Akalin, Enver

    2017-03-01

    We aimed to investigate the impact of the new kidney allocation system (KAS) on the rate of transplantation of sensitized patients at our center. Pre-KAS and post-KAS intervals were Jan 1st to Dec 3rd 2014 and Jan 1st 2015 to Dec 3rd 2015, respectively. The number of deceased-donor crossmatches performed by flow cytometry increased from 715 pre-KAS to 1188 post-KAS. The percent of crossmatches performed for sensitized patients with calculated panel reactive antibody (cPRA)>0% increased from 19% pre-KAS to 26% post-KAS (p<0.0001). The number of deceased-donor kidney transplants performed at our center increased from 115 pre-KAS to 125 post-KAS (9% increase). There was a significant increase in the percentage of deceased-donor kidney transplants received by sensitized candidates (from 14% to 26% pre- and post-KAS, respectively; p<0.0001). The highest increase was seen in the patients with cPRA>98%, from 0% to 9%, followed by the group with cPRA 50-79%, from 5% to 8%. This increase was balanced by a decrease of 12% in the percentage of non-sensitized recipients, and a modest decrease of 1% in the group with cPRA 1-49%. In conclusion, transplant rate has increased in sensitized patients after KAS. The highest increase was observed among highly sensitized patients (cPRA>98%).

  2. An engineered strong promoter for streptomycetes.

    PubMed

    Wang, Weishan; Li, Xiao; Wang, Juan; Xiang, Sihai; Feng, Xiaozhou; Yang, Keqian

    2013-07-01

    Well-characterized promoters are essential tools for metabolic engineering and synthetic biology. In Streptomyces coelicolor, the native kasOp is a temporally expressed promoter strictly controlled by two regulators, ScbR and ScbR2. In this work, first, kasOp was engineered to remove a common binding site of ScbR and ScbR2 upstream of its core region, thus generating a stronger promoter, kasOp3. Second, another ScbR binding site internal to the kasOp3 core promoter region was abolished by random mutation and screening of the mutant library to obtain the strongest promoter, kasOp* (where the asterisk is used to distinguish the engineered promoter from the native promoter). The activities of kasOp* were compared with those of two known strong promoters, ermEp* and SF14p, in three Streptomyces species. kasOp* showed the highest activity at the transcription and protein levels in all three hosts. Furthermore, relative to ermEp* and SF14p, kasOp* was shown to confer the highest actinorhodin production level when used to drive the expression of actII-ORF4 in S. coelicolor. Therefore, kasOp* is a simple and well-defined strong promoter useful for gene overexpression in streptomycetes.

  3. Structure of 3-oxoacyl-(acyl-carrier protein) synthase II from Thermus thermophilus HB8

    PubMed Central

    Bagautdinov, Bagautdin; Ukita, Yoko; Miyano, Masashi; Kunishima, Naoki

    2008-01-01

    The β-ketoacyl-(acyl carrier protein) synthases (β-keto-ACP synthases; KAS) catalyse the addition of two-carbon units to the growing acyl chain during the elongation phase of fatty-acid synthesis. As key regulators of bacterial fatty-acid synthesis, they are promising targets for the development of new antibacterial agents. The crystal structure of 3-oxoacyl-ACP synthase II from Thermus thermophilus HB8 (TtKAS II) has been solved by molecular replacement and refined at 2.0 Å resolution. The crystal is orthorhombic, space group P21212, with unit-cell parameters a = 72.07, b = 185.57, c = 62.52 Å, and contains one homodimer in the asymmetric unit. The subunits adopt the well known α-β-α-β-α thiolase fold that is common to ACP synthases. The structural and sequence similarities of TtKAS II to KAS I and KAS II enzymes of known structure from other sources support the hypothesis of comparable enzymatic activity. The dimeric state of TtKAS II is important to create each fatty-acid-binding pocket. Closer examination of KAS structures reveals that compared with other KAS structures in the apo form, the active site of TtKAS II is more accessible because of the ‘open’ conformation of the Phe396 side chain. PMID:18453702

  4. Structure of 3-oxoacyl-(acyl-carrier protein) synthase II from Thermus thermophilus HB8.

    PubMed

    Bagautdinov, Bagautdin; Ukita, Yoko; Miyano, Masashi; Kunishima, Naoki

    2008-05-01

    The beta-ketoacyl-(acyl carrier protein) synthases (beta-keto-ACP synthases; KAS) catalyse the addition of two-carbon units to the growing acyl chain during the elongation phase of fatty-acid synthesis. As key regulators of bacterial fatty-acid synthesis, they are promising targets for the development of new antibacterial agents. The crystal structure of 3-oxoacyl-ACP synthase II from Thermus thermophilus HB8 (TtKAS II) has been solved by molecular replacement and refined at 2.0 A resolution. The crystal is orthorhombic, space group P2(1)2(1)2, with unit-cell parameters a = 72.07, b = 185.57, c = 62.52 A, and contains one homodimer in the asymmetric unit. The subunits adopt the well known alpha-beta-alpha-beta-alpha thiolase fold that is common to ACP synthases. The structural and sequence similarities of TtKAS II to KAS I and KAS II enzymes of known structure from other sources support the hypothesis of comparable enzymatic activity. The dimeric state of TtKAS II is important to create each fatty-acid-binding pocket. Closer examination of KAS structures reveals that compared with other KAS structures in the apo form, the active site of TtKAS II is more accessible because of the ;open' conformation of the Phe396 side chain.

  5. An Engineered Strong Promoter for Streptomycetes

    PubMed Central

    Wang, Weishan; Li, Xiao; Wang, Juan; Xiang, Sihai; Feng, Xiaozhou

    2013-01-01

    Well-characterized promoters are essential tools for metabolic engineering and synthetic biology. In Streptomyces coelicolor, the native kasOp is a temporally expressed promoter strictly controlled by two regulators, ScbR and ScbR2. In this work, first, kasOp was engineered to remove a common binding site of ScbR and ScbR2 upstream of its core region, thus generating a stronger promoter, kasOp3. Second, another ScbR binding site internal to the kasOp3 core promoter region was abolished by random mutation and screening of the mutant library to obtain the strongest promoter, kasOp* (where the asterisk is used to distinguish the engineered promoter from the native promoter). The activities of kasOp* were compared with those of two known strong promoters, ermEp* and SF14p, in three Streptomyces species. kasOp* showed the highest activity at the transcription and protein levels in all three hosts. Furthermore, relative to ermEp* and SF14p, kasOp* was shown to confer the highest actinorhodin production level when used to drive the expression of actII-ORF4 in S. coelicolor. Therefore, kasOp* is a simple and well-defined strong promoter useful for gene overexpression in streptomycetes. PMID:23686264

  6. Role of depression in diabetes management in an ethnic minority population: a case of Korean Americans with type 2 diabetes

    PubMed Central

    Kim, Miyong To; Kim, Kim Byeng; Ko, Jisook; Jang, Yuri; Levine, David; Lee, Hochang Benjamin

    2017-01-01

    Background Comorbid depression and diabetes mellitus (DM) compound challenges to disease management such as low health literacy, insufficient access to care, and social or linguistic isolation. Korean Americans (KAs), predominantly first-generation immigrants, suffer from a high prevalence of type 2 DM and depression. Limited research on KAs has prevented the development of effective interventions. Objectives To compare the prevalence of depression in KAs with DM and all Americans with/without DM, and to explore correlates of comorbid DM and depression and strategies to address KAs' DM and depression. Methods KAs' data were from a clinical trial of a community-based self-help intervention to improve KAs' DM and mental health outcomes. National Health and Nutrition Examination Survey data sets enabled comparison. Clinical indicators included hemoglobin A1C, lipid panel, and body mass index. Psychobehavioral indicators included self-efficacy for DM management, quality of life, and depression (Patient Health Questionnaire-9 (PHQ-9)). Results More KAs with DM had depression (44.2%) than did all Americans with DM (28.7%) or without DM (20.1%). Significantly more KAs with DM had mild (29.3%) or clinical (14.9%) depression than did Americans with DM (mild, 17.2%; clinical, 11.5%) or without (mild, 13.8%; clinical, 6.3%). One of six KAs with DM (16.9%) thought of suicide or self-harm (Americans with/without =5.0%, 2.8%). The self-help intervention reduced the mean PHQ-9 from 5.4 at baseline to 4.1 at 12 months. Limitations External validity might be limited; KAs' data were from one study site. Conclusions The prevalence of depression and DM among KAs warrants the development of efficacious interventions. Trial registration number NCT01264796. PMID:28405343

  7. Overproduction of a Functional Fatty Acid Biosynthetic Enzyme Blocks Fatty Acid Synthesis in Escherichia coli

    PubMed Central

    Subrahmanyam, Satyanarayana; Cronan, John E.

    1998-01-01

    β-Ketoacyl-acyl carrier protein (ACP) synthetase II (KAS II) is one of three Escherichia coli isozymes that catalyze the elongation of growing fatty acid chains by condensation of acyl-ACP with malonyl-ACP. Overexpression of this enzyme has been found to be extremely toxic to E. coli, much more so than overproduction of either of the other KAS isozymes, KAS I or KAS III. The immediate effect of KAS II overproduction is the cessation of phospholipid synthesis, and this inhibition is specifically due to the blockage of fatty acid synthesis. To determine the cause of this inhibition, we examined the intracellular pools of ACP, coenzyme A (CoA), and their acyl thioesters. Although no significant changes were detected in the acyl-ACP pools, the CoA pools were dramatically altered by KAS II overproduction. Malonyl-CoA increased to about 40% of the total cellular CoA pool upon KAS II overproduction from a steady-state level of around 0.5% in the absence of KAS II overproduction. This finding indicated that the conversion of malonyl-CoA to fatty acids had been blocked and could be explained if either the conversion of malonyl-CoA to malonyl-ACP and/or the elongation reactions of fatty acid synthesis had been blocked. Overproduction of malonyl-CoA:ACP transacylase, the enzyme catalyzing the conversion of malonyl-CoA to malonyl-ACP, partially relieved the toxicity of KAS II overproduction, consistent with a model in which high levels of KAS II blocks access of the other KAS isozymes to malonyl-CoA:ACP transacylase. PMID:9721301

  8. The Influences of Immigration on Health Information Seeking Behaviors among Korean Americans and Native Koreans

    ERIC Educational Resources Information Center

    Oh, Kyeung Mi; Zhou, Qiuping; Kreps, Gary; Kim, Wonsun

    2014-01-01

    Korean Americans (KAs) have low screening rates for cancer and are often not well informed about their chronic diseases. Reduced access to health-related information is one reason for gaps in knowledge and the widening health disparities among minority populations. However, little research exists about KAs' health information seeking behaviors.…

  9. A Manifest Anxiety Scale from the MMPI-168

    ERIC Educational Resources Information Center

    King, M. G.; Campbell, I. M.

    1986-01-01

    Describes the KAS scale, a new composite anxiety scale that comprises items on the Minnesota Multiphasic Personality Inventory-168 (MMPI-168), a popular short form of the MMPI. Relevant normative statistics and the KAS scale relationship with other MMPI scales are discussed. (Author/KS)

  10. The Influences of Immigration on Health Information Seeking Behaviors among Korean Americans and Native Koreans

    ERIC Educational Resources Information Center

    Oh, Kyeung Mi; Zhou, Qiuping; Kreps, Gary; Kim, Wonsun

    2014-01-01

    Korean Americans (KAs) have low screening rates for cancer and are often not well informed about their chronic diseases. Reduced access to health-related information is one reason for gaps in knowledge and the widening health disparities among minority populations. However, little research exists about KAs' health information seeking behaviors.…

  11. Insights from computational analysis of full-length β-ketoacyl-[ACP] synthase-II cDNA isolated from American and African oil palms.

    PubMed

    Bhore, Subhash J; Cha, Thye S; Amelia, Kassim; Shah, Farida H

    2014-01-01

    Palm oil derived from fruits (mesocarp) of African oil palm (Elaeis guineensis Jacq. Tenera) and American oil palm (E. oleifera) is important for food industry. Due to high yield, Elaeis guineensis (Tenera) is cultivated on commercial scale, though its oil contains high (~54%) level of saturated fatty acids. The rate-limiting activity of beta-ketoacyl-[ACP] synthase-II (KAS-II) is considered mainly responsible for the high (44%) level of palmitic acid (C16:0) in the oil obtained from E. guineensis. The objective of this study was to annotate KAS-II cDNA isolated from American and African oil palms. The full-length E. oleifera KAS-II (EoKAS-II) cDNA clone was isolated using random method of gene isolation. Whereas, the E. guineensis KAS-II (EgTKAS-II) cDNA was isolated using reverse transcriptase polymerase chain reaction (RT-PCR) technique; and missing ends were obtained by employing 5'and 3' RACE technique. The results show that EoKAS-II and EgTKAS-II open reading frames (ORFs) are of 1689 and 1721 bp in length, respectively. Further analysis of the both EoKAS-II and EgTKAS-II predicted protein illustrates that they contains conserved domains for 'KAS-I and II', 'elongating' condensing enzymes, 'condensing enzymes super-family', and '3-oxoacyl-[ACP] synthase II'. The predicted protein sequences shows 95% similarity with each other. Consecutively, the three active sites (Cys, His, and His) were identified in both proteins. However, difference in positions of two active Histidine (His) residues was noticed. These insights may serve as the foundation in understanding the variable activity of KAS-II in American and African oil palms; and cDNA clones could be useful in the genetic engineering of oil palms.

  12. Insights from computational analysis of full-length β-ketoacyl-[ACP] synthase-II cDNA isolated from American and African oil palms

    PubMed Central

    Bhore, Subhash J.; Cha, Thye S.; Amelia, Kassim; Shah, Farida H.

    2014-01-01

    Background: Palm oil derived from fruits (mesocarp) of African oil palm (Elaeis guineensis Jacq. Tenera) and American oil palm (E. oleifera) is important for food industry. Due to high yield, Elaeis guineensis (Tenera) is cultivated on commercial scale, though its oil contains high (~54%) level of saturated fatty acids. The rate-limiting activity of beta-ketoacyl-[ACP] synthase-II (KAS-II) is considered mainly responsible for the high (44%) level of palmitic acid (C16:0) in the oil obtained from E. guineensis. Objective: The objective of this study was to annotate KAS-II cDNA isolated from American and African oil palms. Materials and Methods: The full-length E. oleifera KAS-II (EoKAS-II) cDNA clone was isolated using random method of gene isolation. Whereas, the E. guineensis KAS-II (EgTKAS-II) cDNA was isolated using reverse transcriptase polymerase chain reaction (RT-PCR) technique; and missing ends were obtained by employing 5’and 3’ RACE technique. Results: The results show that EoKAS-II and EgTKAS-II open reading frames (ORFs) are of 1689 and 1721 bp in length, respectively. Further analysis of the both EoKAS-II and EgTKAS-II predicted protein illustrates that they contains conserved domains for ‘KAS-I and II’, ‘elongating’ condensing enzymes, ‘condensing enzymes super-family’, and ‘3-oxoacyl-[ACP] synthase II’. The predicted protein sequences shows 95% similarity with each other. Consecutively, the three active sites (Cys, His, and His) were identified in both proteins. However, difference in positions of two active Histidine (His) residues was noticed. Conclusion: These insights may serve as the foundation in understanding the variable activity of KAS-II in American and African oil palms; and cDNA clones could be useful in the genetic engineering of oil palms. PMID:24678202

  13. Structure of 3-oxoacyl-(acyl-carrier protein) synthase II from Thermus thermophilus HB8

    SciTech Connect

    Bagautdinov, Bagautdin Ukita, Yoko; Miyano, Masashi; Kunishima, Naoki

    2008-05-01

    The crystal structure of 3-oxoacyl-(acyl-carrier protein) synthase II from T. thermophilus HB8 has been determined at 2.0 Å resolution and compared with the structures of β-keto-ACP synthases from other sources. The β-ketoacyl-(acyl carrier protein) synthases (β-keto-ACP synthases; KAS) catalyse the addition of two-carbon units to the growing acyl chain during the elongation phase of fatty-acid synthesis. As key regulators of bacterial fatty-acid synthesis, they are promising targets for the development of new antibacterial agents. The crystal structure of 3-oxoacyl-ACP synthase II from Thermus thermophilus HB8 (TtKAS II) has been solved by molecular replacement and refined at 2.0 Å resolution. The crystal is orthorhombic, space group P2{sub 1}2{sub 1}2, with unit-cell parameters a = 72.07, b = 185.57, c = 62.52 Å, and contains one homodimer in the asymmetric unit. The subunits adopt the well known α-β-α-β-α thiolase fold that is common to ACP synthases. The structural and sequence similarities of TtKAS II to KAS I and KAS II enzymes of known structure from other sources support the hypothesis of comparable enzymatic activity. The dimeric state of TtKAS II is important to create each fatty-acid-binding pocket. Closer examination of KAS structures reveals that compared with other KAS structures in the apo form, the active site of TtKAS II is more accessible because of the ‘open’ conformation of the Phe396 side chain.

  14. The Impact of the New Kidney Allocation System on Prior Living Kidney Donors' Access to Deceased Donor Kidney Transplants: An Early Look.

    PubMed

    Wainright, J L; Kucheryavaya, A Y; Klassen, D K; Stewart, D E

    2017-04-01

    This study investigated the early effects of the new kidney allocation system (KAS) on the access of prior living kidney donors (PLDs) to deceased donor kidney transplants. Using data from the Organ Procurement and Transplantation Network, we compared prevalent and incident cohorts of PLDs in the 1-year periods before and after KAS implementation (pre-KAS group: December 4, 2013, to December 3, 2014, n = 50 [newly listed PLDs]; post-KAS group: December 4, 2014, to December 3, 2015, n = 39). We assessed transplant rates per active patient-year, waiting times, and Kidney Donor Profile Index (KDPI) of transplanted kidneys. Transplant rates were not statistically different before and after KAS implementation for either prevalent (2.37 vs. 2.29, relative risk [RR] 0.96; 95% confidence interval [CI] 0.62-1.49) or incident (4.76 vs. 4.36, RR 0.92; 95% CI 0.53-1.60) candidates. Median waiting time (MWT) to deceased donor kidney transplant for prevalent PLDs in the post-KAS cohort was 102.6 days compared with 82.3 days in the pre-KAS cohort (p = 0.98). The median KDPI for PLD recipients was 31% with KAS versus 23% before KAS (p = 0.02). Despite a sharp decrease in the MWT for highly prioritized candidates with calculated panel reactive antibodies of 98-100% (from >7000 to 1164 days), PLDs still had much shorter waiting times (MWT 102.6 days). The new system continues to provide quick access to high-quality organs for PLDs.

  15. Assessment of Alzheimer's disease symptom recognition in Korean Americans and psychometric analysis of Alzheimer's Disease Symptom Recognition Scale (ADSRS).

    PubMed

    Lee, Sang E; Casado, Banghwa Lee

    2015-01-01

    This study examined recognition of Alzheimer's disease symptoms among Korean Americans (KAs) and assessed psychometric properties of the Alzheimer's Disease Symptom Recognition Scale (ADSRS). A cross-sectional survey collected data from 209 KAs, using a self-administered questionnaire. Results show that KAs recognized symptoms related to memory and cognitive functioning well, but had very limited recognition of neuropsychiatric symptoms. Psychometric analysis of ADSRS identified 4 factors in their symptom recognition. Findings suggest a need to raise awareness of Alzheimer's symptoms over the course of the disease. Assessment using ADSRS can be incorporated in communication in the practice context and public outreach.

  16. Beta-ketoacyl-acyl carrier protein synthase III from pea (Pisum sativum L.): properties, inhibition by a novel thiolactomycin analogue and isolation of a cDNA clone encoding the enzyme.

    PubMed

    Jones, A Lesley; Gane, Andy M; Herbert, Derek; Willey, David L; Rutter, Andrew J; Kille, Peter; Dancer, Jane E; Harwood, John L

    2003-03-01

    A beta-ketoacyl-acyl carrier protein (ACP) synthase III (KAS III; short-chain condensing enzyme) has been partly purified from pea leaves. The enzyme, which had acetyl-CoA:ACP acyltransferase (ACAT) activity, was resolved from a second, specific, ACAT protein. The KAS III enzyme had a derived molecular mass of 42 kDa (from its cDNA sequence) and operated as a dimer. Its enzymological characteristics were similar to those of two other plant KAS III enzymes except for its inhibition by thiolactomycin. A derivative of thiolactomycin containing a longer (C8 saturated) hydrophobic side-chain (compound 332) was a more effective inhibitor of pea KAS III and showed competitive inhibition towards malonyl-ACP whereas thiolactomycin showed uncompetitive characteristics at high concentrations. This difference may be due to the better fit of compound 332 into a hydrophobic pocket at the active site. A full-length cDNA for the pea KAS III was isolated. This was expressed in Escherichia coli as a fusion protein with glutathione S-transferase in order to facilitate subsequent purification. Demonstrated activity in preparations from E. coli confirmed that the cDNA encoded a KAS III enzyme. Furthermore, the expressed KAS III had ACAT activity, showing that the latter was inherent. The derived amino acid sequence of the pea cDNA showed 81-87% similarity to that for other plant dicotyledon KAS IIIs, somewhat less for Allium porrum (leek, 71%) and for Porphyra spp. (62%), Synechocystis spp. (65%) and various bacteria (42-65%). The pea KAS III exhibited four areas of homology, three of which were around the active-site Cys(123), His(323) and Asn(353). In addition, a stretch of 23 amino acids (residues 207-229 in the pea KAS III) was almost completely conserved in the plant KAS IIIs. Modelling this stretch showed they belonged to a peptide fragment that fitted over the active site and contained segments suggested to be involved in substrate binding and in conformational changes during

  17. Early Changes in Kidney Distribution under the New Allocation System.

    PubMed

    Massie, Allan B; Luo, Xun; Lonze, Bonnie E; Desai, Niraj M; Bingaman, Adam W; Cooper, Matthew; Segev, Dorry L

    2016-08-01

    The Kidney Allocation System (KAS), a major change to deceased donor kidney allocation, was implemented in December 2014. Goals of KAS included directing the highest-quality organs to younger/healthier recipients and increasing access to deceased donor kidney transplantation (DDKT) for highly sensitized patients and racial/ethnic minorities. Using national registry data, we compared kidney distribution, DDKT rates for waitlist registrants, and recipient characteristics between January 1, 2013, and December 3, 2014 (pre-KAS) with those between December 4, 2014, and August 31, 2015 (post-KAS). Regional imports increased from 8.8% pre-KAS to 12.5% post-KAS; national imports increased from 12.7% pre-KAS to 19.1% post-KAS (P<0.001). The proportion of recipients >30 years older than their donor decreased from 19.4% to 15.0% (P<0.001). The proportion of recipients with calculated panel-reactive antibody =100 increased from 1.0% to 10.3% (P<0.001). Overall DDKT rate did not change as modeled using exponential regression adjusting for candidate characteristics (P=0.07). However, DDKT rate (incidence rate ratio, 95% confidence interval) increased for black (1.19; 1.13 to 1.25) and Hispanic (1.13; 1.05 to 1.20) candidates and for candidates aged 18-40 (1.47; 1.38 to 1.57), but declined for candidates aged >50 (0.93; 0.87 to 0.98 for aged 51-60 and 0.90; 0.85 to 0.96 for aged >70). Delayed graft function in transplant recipients increased from 24.8% pre-KAS to 29.9% post-KAS (P<0.001). Thus, in the first 9 months under KAS, access to DDKT improved for minorities, younger candidates, and highly sensitized patients, but declined for older candidates. Delayed graft function increased substantially, possibly suggesting poorer long-term outcomes. Copyright © 2016 by the American Society of Nephrology.

  18. Retroactive application of the new kidney allocation system to renal transplants performed in the ECD/SCD era.

    PubMed

    Ramanathan, Rajesh; Gupta, Gaurav; Kim, Joohyun; Quinn, Keri; Behnke, Martha; Kang, Le; Sharma, Amit

    2015-12-01

    The kidney allocation system (KAS) aims to improve deceased donor kidney transplant outcomes by matching of donor allografts and kidney recipients using the kidney donor risk index (KDRI) and recipient estimated post-transplant survival (EPTS) indices. In this single-center study, KAS was retroactively applied to 573 adult deceased donor kidney transplants (2004-2012) performed in the extended criteria/standard criteria donor (ECD/SCD) era. Donor KDRI and recipient EPTS were calculated, and transplants were analyzed to identify KAS fits. These were defined as allocation of top 20% allografts to top 20% recipients and bottom 80% allografts to bottom 80% recipients. On retroactive calculation, 70.2% of all transplants fit the KAS. Transplants that fit the KAS had inferior 1- and 5-yr patient survival (95.5% vs. 98.8%, p = 0.048, and 83.4% vs. 91.7%, p = 0.018) and similar 1- and 5-yr graft survival compared to transplants that did not fit the KAS (91.3% vs. 94.1%, p = 0.276, and 72.7% vs. 73.9%, p = 0.561). While EPTS correlated with recipient survival (HR = 2.96, p < 0.001), KDRI correlated with both recipient (HR = 3.56, p < 0.001) and graft survival (HR = 3.23, p < 0.001). Overall, retroactive application of the KAS to transplants performed in the ECD/SCD era did not identify superior patient survival for kidneys allocated in accordance with the KAS. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. The influences of immigration on health information seeking behaviors among Korean Americans and Native Koreans.

    PubMed

    Oh, Kyeung Mi; Zhou, Qiuping Pearl; Kreps, Gary; Kim, Wonsun

    2014-04-01

    Korean Americans (KAs) have low screening rates for cancer and are often not well informed about their chronic diseases. Reduced access to health-related information is one reason for gaps in knowledge and the widening health disparities among minority populations. However, little research exists about KAs' health information seeking behaviors. Guided by the Structural Influence Model, this study examines the influence of immigration status on KAs' trust in health information sources and health information seeking behaviors. Cross-sectional surveys were conducted in the Washington, D.C., metropolitan area as well as in the Gwangju metropolitan city in South Korea during 2006-2007. Two hundred and fifty-four KAs and 208 native Koreans who were 40 years of age or older completed the surveys. When comparing native Koreans to KAs, we found KAs were 3 times more likely to trust health information from newspapers or magazines (odds ratio [OR] = 3.13; 95% confidence interval [CI] = 1.49-6.54) and 11 times more likely to read the health sections of newspapers or magazines (OR = 11.35; 95% CI = 3.92-32.91) in multivariate adjusted models. However, they were less likely to look for health information from TV (OR = 0.29; 95% CI = 0.12-0.72) than native Koreans. Our results indicate that immigration status has profound influences on KAs' health information seeking behaviors. Increasing the availability of reliable and valid health information from printed Korean language magazines or newspapers could have a positive influence on increasing awareness and promoting screening behaviors among KAs.

  20. Aqueous dissociation constants of bile pigments and sparingly soluble carboxylic acids by 13C NMR in aqueous dimethyl sulfoxide: effects of hydrogen bonding.

    PubMed

    Trull, F R; Boiadjiev, S; Lightner, D A; McDonagh, A F

    1997-06-01

    pKas for the acid dissociation of the carboxyl groups of bilirubin in water have been reported recently to be 8.1-8.4, or higher. These high values were attributed to intramolecular hydrogen bonding. They have led to suggestions that monoanions of bilirubin predominate at physiologic pH and are the species transported most readily into hepatocytes by carriers. Such high aqueous pKas are inconsistent with recent 13C nuclear magnetic resonance (NMR) measurements on mesobilirubin XIII alpha, done on aqueous solutions containing dimethyl sulfoxide. To investigate whether the presence of dimethyl sulfoxide leads to unreliable values when using 13C NMR spectroscopy to determine pKas of carboxylic acids that can undergo intramolecular hydrogen bonding, we measured the pKas of 13C-labeled fumaric, maleic, and phthalic acids in solutions containing up to 27 vol% dimethyl sulfoxide. In addition, we used 13C NMR to estimate the pKas of 2,2'-methylenebis[5-carbomethoxy-4-methylpyrrole-3-[1-13C] propanoic acid], a model for the two central rings of bilirubin. Our results show that 13C NMR of aqueous dimethyl sulfoxide solutions can be used with confidence to measure pKas of intramolecularly hydrogen-bonded carboxylic acids. They support our previous estimates for the pKas of bilirubin and confirm that intramolecular hydrogen bonding has little effect on the acidity of bilirubins in water. Together with previous studies and chemical arguments they strongly suggest that reported aqueous pKas of > 8, or even > 6, for the carboxyl groups of bilirubin are incorrect and that arguments used to rationalize them are questionable.

  1. A single membrane-bound enzyme catalyzes the conversion of 2,5-diketo-d-gluconate to 4-keto-d-arabonate in d-glucose oxidative fermentation by Gluconobacter oxydans NBRC 3292.

    PubMed

    Tazoe, Masaaki; Oishi, Hiromi; Kobayashi, Setsuko; Hoshino, Tatsuo

    2016-08-01

    4-Keto-d-arabonate synthase (4KAS), which converts 2,5-diketo-d-gluconate (DKGA) to 4-keto-d-arabonate (4KA) in d-glucose oxidative fermentation by some acetic acid bacteria, was solubilized from the Gluconobacter oxydans NBRC 3292 cytoplasmic membrane, and purified in an electrophoretically homogenous state. A single membrane-bound enzyme was found to catalyze the conversion from DKGA to 4KA. The 92-kDa 4KAS was a homodimeric protein not requiring O2 or a cofactor for the conversion, but was stimulated by Mn(2+). N-terminal amino acid sequencing of 4KAS, followed by gene homology search indicated a 1,197-bp open reading frame (ORF), corresponding to the GLS_c04240 locus, GenBank accession No. CP004373, encoding a 398-amino acid protein with a calculated molecular weight of 42,818 Da. An Escherichia coli transformant with the 4kas plasmid exhibited 4KAS activity. Furthermore, overexpressed recombinant 4KAS was purified in an electrophoretically homogenous state and had the same molecular size as the natural enzyme.

  2. 3-Ketoacyl-acyl carrier protein synthase III from spinach (Spinacia oleracea) is not similar to other condensing enzymes of fatty acid synthase.

    PubMed Central

    Tai, H; Jaworski, J G

    1993-01-01

    A cDNA clone encoding spinach (Spinacia oleracea) 3-ketoacyl-acyl carrier protein synthase III (KAS III), which catalyzes the initial condensing reaction in fatty acid biosynthesis, was isolated. Based on the amino acid sequence of tryptic digests of purified spinach KAS III, degenerate polymerase chain reaction (PCR) primers were designed and used to amplify a 612-bp fragment from first-strand cDNA of spinach leaf RNA. A root cDNA library was probed with the PCR fragment, and a 1920-bp clone was isolated. Its deduced amino acid sequence matched the sequences of the tryptic digests obtained from the purified KAS III. Northern analysis confirmed that it was expressed in both leaf and root. The clone contained a 1218-bp open reading frame coding for 405 amino acids. The identity of the clone was confirmed by expression in Escherichia coli BL 21 as a glutathione S-transferase fusion protein. The deduced amino acid sequence was 48 and 45% identical with the putative KAS III of Porphyra umbilicalis and KAS III of E. coli, respectively. It also had a strong local homology to the plant chalcone synthases but had little homology with other KAS isoforms from plants, bacteria, or animals. PMID:8290632

  3. 3D geological modeling of the Kasserine Aquifer System, Central Tunisia: New insights into aquifer-geometry and interconnections for a better assessment of groundwater resources

    NASA Astrophysics Data System (ADS)

    Hassen, Imen; Gibson, Helen; Hamzaoui-Azaza, Fadoua; Negro, François; Rachid, Khanfir; Bouhlila, Rachida

    2016-08-01

    The challenge of this study was to create a 3D geological and structural model of the Kasserine Aquifer System (KAS) in central Tunisia and its natural extension into north-east Algeria. This was achieved using an implicit 3D method, which honors prior geological data for both formation boundaries and faults. A current model is presented which provides defendable predictions for the spatial distribution of geology and water resources in aquifers throughout the model-domain. This work has allowed validation of regional scale geology and fault networks in the KAS, and has facilitated the first-ever estimations of groundwater resources in this region by a 3D method. The model enables a preliminary assessment of the hydraulic significance of the major faults by evaluating their influence and role on groundwater flow within and between four compartments of the multi-layered, KAS hydrogeological system. Thus a representative hydrogeological model of the study area is constructed. The possible dual nature of faults in the KAS is discussed in the context that some faults appear to be acting both as barriers to horizontal groundwater flow, and simultaneously as conduits for vertical flow. Also discussed is the possibility that two flow directions occur within the KAS, at a small syncline area of near Feriana. In summary, this work evaluates the influence of aquifer connectivity and the role of faults and geology in groundwater flow within the KAS aquifer system. The current KAS geological model can now be used to guide groundwater managers on the best placement for drilling to test and further refine the understanding of the groundwater system, including the faults connectivity. As more geological data become available, the current model can be easily edited and re-computed to provide an updated model ready for the next stage of investigation by numerical flow modeling.

  4. Modification of Brassica napus seed oil by expression of the Escherichia coli fabH gene, encoding 3-ketoacyl-acyl carrier protein synthase III.

    PubMed

    Verwoert, I I; van der Linden, K H; Walsh, M C; Nijkamp, H J; Stuitje, A R

    1995-03-01

    The Escherichia coli fabH gene encoding 3-ketoacyl-acyl carrier protein synthase III (KAS III) was isolated and the effect of overproduction of bacterial KAS III was compared in both E. coli and Brassica napus. The change in fatty acid profile of E. coli was essentially the same as that reported by Tsay et al. (J Biol Chem 267 (1992) 6807-6814), namely higher C14:0 and lower C18:1 levels. In our study, however, an arrest of cell growth was also observed. This and other evidence suggests that in E. coli the accumulation of C14:0 may not be a direct effect of the KAS III overexpression, but a general metabolic consequence of the arrest of cell division. Bacterial KAS III was expressed in a seed- and developmentally specific manner in B. napus in either cytoplasm or plastid. Significant increases in KAS III activities were observed in both these transformation groups, up to 3.7 times the endogenous KAS III activity in mature seeds. Only the expression of the plastid-targeted KAS III gene, however, affected the fatty acid profile of the storage lipids, such that decreased amounts of C18:1 and increased amounts of C18:2 and C18:3 were observed as compared to control plants. Such changes in fatty acid composition reflect changes in the regulation and control of fatty acid biosynthesis. We propose that fatty acid biosynthesis is not controlled by one rate-limiting enzyme, such as acetyl-CoA carboxylase, but rather is shared by a number of component enzymes of the fatty acid biosynthetic machinery.

  5. Keto Amphetamine Toxicity—Focus on the Redox Reactivity of the Cathinone Designer Drug Mephedrone

    PubMed Central

    den Hollander, Bjørnar; Sundström, Mira; Pelander, Anna; Ojanperä, Ilkka; Mervaala, Eero; Korpi, Esa Risto; Kankuri, Esko

    2014-01-01

    The β-keto amphetamine (cathinone, β-KA) designer drugs such as mephedrone (4-methylmethcathinone, 4-MMC) show a large degree of structural similarity to amphetamines like methamphetamine (METH). However, little is currently known about whether these substances also share the potential neurotoxic properties of their non-keto amphetamine counterparts, or what mechanisms could be involved. Here, we evaluate the cytotoxicity of β-KAs in SH-SY5Y cells using lactate dehydrogenase (LDH) assays, assess the redox potential of a range of β-KAs and non-keto amphetamines using the sensitive redox indicator 2-(4-Iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium (WST-1), and explore the effect of 4-MMC on the formation of protein adducts using ultra-high performance liquid chromatography/high-resolution time-of-flight mass spectrometry (UHPLC-HR-TOFMS) and on the mitochondrial respiratory chain using high-resolution respirometry. We show that treatment with β-KAs increases LDH release. Further, we demonstrate that even under physiological pH, β-KAs are effective and selective—as compared with their non-keto analogues—reductants in the presence of electron acceptors. Increased pH (range 7.6–8.0) greatly enhanced the reactivity up to sixfold. We found no evidence of protein adduct formation, suggesting the reactivity is due to direct electron transfer by the β-KAs. Finally, we show that 4-MMC and METH produce dissimilar effects on the respiratory chain. Our results indicate that β-KAs such as 4-MMC possess cytotoxic properties in vitro. Furthermore, in the presence of an electron-accepting redox partner, the ketone moiety of β-KAs is vital for pH-dependent redox reactivity. Further work is needed to establish the importance of β-KA redox properties and its potential toxicological importance in vivo. PMID:24913801

  6. Effect of a multi-level education intervention model on knowledge and attitudes of accidental injuries in rural children in Zunyi, Southwest China.

    PubMed

    Cao, Bo-Ling; Shi, Xiu-Quan; Qi, Yong-Hong; Hui, Ya; Yang, Hua-Jun; Shi, Shang-Peng; Luo, Li-Rong; Zhang, Hong; Wang, Xin; Yang, Ying-Ping

    2015-04-08

    To explore the effect of a school-family-individual (SFI) multi-level education intervention model on knowledge and attitudes about accidental injuries among school-aged children to improve injury prevention strategies and reduce the incidence of pediatric injuries. The random sample of rural school-aged children were recruited by using a multistage, stratified, cluster sampling method in Zunyi, Southwest China from 2012 to 2014, and 2342 children were randomly divided into intervention and control groups. Then children answered a baseline survey to collect knowledge and attitude scores (KAS) of accidental injuries. In the intervention group, children, their parents/guardians and the school received a SFI multi-level education intervention, which included a children's injury-prevention poster at schools, an open letter about security instruction for parents/guardians and multiple-media health education (Microsoft PowerPoint lectures, videos, handbooks, etc.) to children. Children in the control group were given only handbook education. After 16 months, children answered a follow-up survey to collect data on accidental injury types and accidental injury-related KAS for comparing the intervention and control groups and baseline and follow-up data. The distribution of gender was not significantly different while age was different between the baseline and follow-up survey. At baseline, the mean KAS was lower for the intervention than control group (15.37 ± 3.40 and 18.35 ± 5.01; p < 0.001). At follow-up, the mean KAS was higher for the intervention than control group (21.16 ± 3.05 and 20.02 ± 3.40; p < 0.001). The increase in KAS in the intervention and control groups was significant (p < 0.001; KAS: 5.79 vs. 1.67) and suggested that children's injury-related KAS improved in the intervention group. Moreover, the KAS between the groups differed for most subtypes of incidental injuries (based on International Classification of Diseases 10, ICD-10) (p < 0.05). Before

  7. Effect of a Multi-Level Education Intervention Model on Knowledge and Attitudes of Accidental Injuries in Rural Children in Zunyi, Southwest China

    PubMed Central

    Cao, Bo-Ling; Shi, Xiu-Quan; Qi, Yong-Hong; Hui, Ya; Yang, Hua-Jun; Shi, Shang-Peng; Luo, Li-Rong; Zhang, Hong; Wang, Xin; Yang, Ying-Ping

    2015-01-01

    Objective: To explore the effect of a school-family-individual (SFI) multi-level education intervention model on knowledge and attitudes about accidental injuries among school-aged children to improve injury prevention strategies and reduce the incidence of pediatric injuries. Methods: The random sample of rural school-aged children were recruited by using a multistage, stratified, cluster sampling method in Zunyi, Southwest China from 2012 to 2014, and 2342 children were randomly divided into intervention and control groups. Then children answered a baseline survey to collect knowledge and attitude scores (KAS) of accidental injuries. In the intervention group, children, their parents/guardians and the school received a SFI multi-level education intervention, which included a children’s injury-prevention poster at schools, an open letter about security instruction for parents/guardians and multiple-media health education (Microsoft PowerPoint lectures, videos, handbooks, etc.) to children. Children in the control group were given only handbook education. After 16 months, children answered a follow-up survey to collect data on accidental injury types and accidental injury-related KAS for comparing the intervention and control groups and baseline and follow-up data. Results: The distribution of gender was not significantly different while age was different between the baseline and follow-up survey. At baseline, the mean KAS was lower for the intervention than control group (15.37 ± 3.40 and 18.35 ± 5.01; p < 0.001). At follow-up, the mean KAS was higher for the intervention than control group (21.16 ± 3.05 and 20.02 ± 3.40; p < 0.001). The increase in KAS in the intervention and control groups was significant (p < 0.001; KAS: 5.79 vs. 1.67) and suggested that children’s injury-related KAS improved in the intervention group. Moreover, the KAS between the groups differed for most subtypes of incidental injuries (based on International Classification of

  8. Attitudes Toward Alzheimer's Care-Seeking Among Korean Americans: Effects of Knowledge, Stigma, and Subjective Norm.

    PubMed

    Casado, Banghwa Lee; Hong, Michin; Lee, Sang E

    2017-03-10

    Early detection of Alzheimer's disease (AD) ensures that affected individuals and their caregivers can make appropriate plans for health care needs, yet many ethnic minorities delay seeking care for AD until the disease has progressed. This study examined attitudes toward care-seeking for AD among Korean Americans (KAs) and identified factors affecting their attitudes. A cross-sectional survey was used to collect data from 234 KA adults. We conducted hierarchical regression analyses to examine the effects of sociocultural background (age, gender, education, cultural orientation), AD knowledge and exposure to AD, and beliefs about AD (stigma of pity, shame, and public avoidance) and AD care (subjective norm) on KAs' attitudes toward seeking AD care from primary care physicians (PCPs) and AD specialists. We also tested whether knowledge of AD moderated the impact of beliefs about AD and AD care on KAs' attitudes toward seeking AD care. For both PCPs and AD specialists, the subjective norm had the strongest effect on KAs' attitudes toward care seeking (β = 0.557 for PCPs, β = 0.360 for specialists). Effects of stigma beliefs disappeared in the presence of the subjective norm. AD knowledge moderated the impact of the subjective norm on the attitudes toward both PCPs (β = -1.653) and specialists (β = -1.742). The significance of the subjective norm in KAs' attitudes toward AD care-seeking underscores the importance of public education, and our study suggests that increasing AD knowledge could facilitate a change in public attitudes toward seeking AD care.

  9. Diversion of phagosome trafficking by pathogenic Rhodococcus equi depends on mycolic acid chain length

    PubMed Central

    Sydor, Tobias; Bargen, Kristine; Hsu, Fong-Fu; Huth, Gitta; Holst, Otto; Wohlmann, Jens; Becken, Ulrike; Dykstra, Tobias; Söhl, Kristina; Lindner, Buko; Prescott, John F; Schaible, Ulrich E; Utermöhlen, Olaf; Haas, Albert

    2013-01-01

    Rhodococcus equi is a close relative of Mycobacterium spp. and a facultative intracellular pathogen which arrests phagosome maturation in macrophages before the late endocytic stage. We have screened a transposon mutant library of R. equi for mutants with decreased capability to prevent phagolysosome formation. This screen yielded a mutant in the gene for β-ketoacyl-(acyl carrier protein)-synthase A (KasA), a key enzyme of the long-chain mycolic acid synthesizing FAS-II system. The longest kasA mutant mycolic acid chains were 10 carbon units shorter than those of wild-type bacteria. Coating of non-pathogenic E. coli with purified wild-type trehalose dimycolate reduced phagolysosome formation substantially which was not the case with shorter kasA mutant-derived trehalose dimycolate. The mutant was moderately attenuated in macrophages and in a mouse infection model, but was fully cytotoxic.Whereas loss of KasA is lethal in mycobacteria, R. equi kasA mutant multiplication in broth was normal proving that long-chain mycolic acid compounds are not necessarily required for cellular integrity and viability of the bacteria that typically produce them. This study demonstrates a central role of mycolic acid chain length in diversion of trafficking by R. equi. PMID:23078612

  10. Diversion of phagosome trafficking by pathogenic Rhodococcus equi depends on mycolic acid chain length.

    PubMed

    Sydor, Tobias; von Bargen, Kristine; Hsu, Fong-Fu; Huth, Gitta; Holst, Otto; Wohlmann, Jens; Becken, Ulrike; Dykstra, Tobias; Söhl, Kristina; Lindner, Buko; Prescott, John F; Schaible, Ulrich E; Utermöhlen, Olaf; Haas, Albert

    2013-03-01

    Rhodococcus equi is a close relative of Mycobacterium spp. and a facultative intracellular pathogen which arrests phagosome maturation in macrophages before the late endocytic stage. We have screened a transposon mutant library of R. equi for mutants with decreased capability to prevent phagolysosome formation. This screen yielded a mutant in the gene for β-ketoacyl-(acyl carrier protein)-synthase A (KasA), a key enzyme of the long-chain mycolic acid synthesizing FAS-II system. The longest kasA mutant mycolic acid chains were 10 carbon units shorter than those of wild-type bacteria. Coating of non-pathogenic E. coli with purified wild-type trehalose dimycolate reduced phagolysosome formation substantially which was not the case with shorter kasA mutant-derived trehalose dimycolate. The mutant was moderately attenuated in macrophages and in a mouse infection model, but was fully cytotoxic.Whereas loss of KasA is lethal in mycobacteria, R. equi kasA mutant multiplication in broth was normal proving that long-chain mycolic acid compounds are not necessarily required for cellular integrity and viability of the bacteria that typically produce them. This study demonstrates a central role of mycolic acid chain length in diversion of trafficking by R. equi. © 2012 Blackwell Publishing Ltd.

  11. Speciation, Luminescence, and Alkaline Fluorescence Quenching of 4-(2-Methylbutyl)aminodipicolinic acid (H2MEBADPA)

    PubMed Central

    Ingram, Andrew J.; Dunlap, Alexander G.; DiPietro, Richard; Muller, Gilles

    2011-01-01

    4-(2-methylbutyl)aminodipicolinic acid (H2MEBADPA) has been synthesized and fully characterized in terms of aqueous phase protonation 0constants (pKas) and photophysical measurements. The pKas were determined by spectrophotometric titrations, utilizing a fully sealed titration system. Photophysical measurements consisted of room temperature fluorescence and frozen solution phosphorescence as well as quantum yield determinations at various pH which showed that only fully deprotonated MEBADPA2− is appreciably emissive. The fluorescence of MEBADPA2− has been determined to be quenched by hydroxide and methoxide anions, most likely through base-catalyzed excited-state tautomerism or proton transfer. This quenching phenomenon has been quantitatively explored through steady-state and time-resolved fluorescence measurements. Utilizing the determined pKas and quenching constants, the fluorescent intensity of MEBADPA2− has been successfully modeled as a function of pH. PMID:21630701

  12. Small-conductance calcium-activated potassium channel and recurrent ventricular fibrillation in failing rabbit ventricles.

    PubMed

    Chua, Su-Kiat; Chang, Po-Cheng; Maruyama, Mitsunori; Turker, Isik; Shinohara, Tetsuji; Shen, Mark J; Chen, Zhenhui; Shen, Changyu; Rubart-von der Lohe, Michael; Lopshire, John C; Ogawa, Masahiro; Weiss, James N; Lin, Shien-Fong; Ai, Tomohiko; Chen, Peng-Sheng

    2011-04-15

    Fibrillation/defibrillation episodes in failing ventricles may be followed by action potential duration (APD) shortening and recurrent spontaneous ventricular fibrillation (SVF). We hypothesized that activation of apamin-sensitive small-conductance Ca(2+)-activated K(+) (SK) channels is responsible for the postshock APD shortening in failing ventricles. A rabbit model of tachycardia-induced heart failure was used. Simultaneous optical mapping of intracellular Ca(2+) and membrane potential (V(m)) was performed in failing and nonfailing ventricles. Three failing ventricles developed SVF (SVF group); 9 did not (no-SVF group). None of the 10 nonfailing ventricles developed SVF. Increased pacing rate and duration augmented the magnitude of APD shortening. Apamin (1 μmol/L) eliminated recurrent SVF and increased postshock APD(80) in the SVF group from 126±5 to 153±4 ms (P<0.05) and from 147±2 to 162±3 ms (P<0.05) in the no-SVF group but did not change APD(80) in nonfailing group. Whole cell patch-clamp studies at 36°C showed that the apamin-sensitive K(+) current (I(KAS)) density was significantly larger in the failing than in the normal ventricular epicardial myocytes, and epicardial I(KAS) density was significantly higher than midmyocardial and endocardial myocytes. Steady-state Ca(2+) response of I(KAS) was leftward-shifted in the failing cells compared with the normal control cells, indicating increased Ca(2+) sensitivity of I(KAS) in failing ventricles. The K(d) was 232±5 nmol/L for failing myocytes and 553±78 nmol/L for normal myocytes (P=0.002). Heart failure heterogeneously increases the sensitivity of I(KAS) to intracellular Ca(2+), leading to upregulation of I(KAS), postshock APD shortening, and recurrent SVF.

  13. Apamin-Sensitive Small Conductance Calcium-Activated Potassium Channels were Negatively Regulated by Captopril in Volume-Overload Heart Failure Rats.

    PubMed

    Hongyuan, Bai; Xin, Dong; Jingwen, Zhang; Li, Gao; Yajuan, Ni

    2016-08-01

    In heart failure (HF), the malignant arrhythmias occur frequently; a study demonstrated that upregulation of I KAS resulted in recurrent spontaneous ventricular fibrillation in HF. However, the regulation of SK channels was poorly understood. The activation of SK channels depended on [Ca(2+)]i and PP2A; studies suggested that angiotensin II can regulate them. So, we hypothesized that in HF, the excess of angiotensin may regulate the SK channels and result in the remodeling of SK channels. To test the hypothesis, we used volume-overload-induced HF rat model, treated with captopril, performed whole-cell patch clamp to record apamin-sensitive currents (I KAS), and I-V curve was studied. The sensitivity of I KAS to [Ca(2+)]i was also explored by setting various [Ca(2+)]i (10, 100, 500, 900, 1000, and 10,000 nM), and the steady-state Ca(2+) response of I KAS was attained and performed Hill fitting with the equation (y = 1/[1 + (EC50/x) (n) ]). Immunofluorescent staining, real-time PCR, Western blot were also carried out to furtherly investigate the underlying molecular mechanisms of the regulation. Captopril significantly decreased the mean density of I KAS when [Ca(2+)]i was 500, 900, 1000, and 10000 nM. The Hill fitting showed significantly different EC50 values and the Hill coefficients and showed captopril significantly shifted rightward the steady-state Ca(2+) response of I KAS. The results of real-time PCR and Western blot demonstrated captopril decreased the mRNA and protein expression of SK3 channels. Captopril significantly downregulated the sensitivity of SK channels to [Ca(2+)]i and the SK3 channels expression in HF, and reversed the SK channels remodeling.

  14. Knowledge and abilities catalog for nuclear power plant operators: Boiling water reactors, Revision 1

    SciTech Connect

    1995-08-01

    The Knowledge and Abilities Catalog for Nuclear Power Plant Operators: Boiling-Water Reactors (BWRs) (NUREG-1123, Revision 1) provides the basis for the development of content-valid licensing examinations for reactor operators (ROs) and senior reactor operators (SROs). The examinations developed using the BWR Catalog along with the Operator Licensing Examiner Standards (NUREG-1021) and the Examiner`s Handbook for Developing Operator Licensing Written Examinations (NUREG/BR-0122), will cover the topics listed under Title 10, Code of Federal Regulations, Part 55 (10 CFR 55). The BWR Catalog contains approximately 7,000 knowledge and ability (K/A) statements for ROs and SROs at BWRs. The catalog is organized into six major sections: Organization of the Catalog, Generic Knowledge and Ability Statements, Plant Systems grouped by Safety Functions, Emergency and Abnormal Plant Evolutions, Components, and Theory. Revision 1 to the BWR Catalog represents a modification in form and content of the original catalog. The K/As were linked to their applicable 10 CFR 55 item numbers. SRO level K/As were identified by 10 CFR 55.43 item numbers. The plant-wide generic and system generic K/As were combined in one section with approximately one hundred new K/As. Component Cooling Water and Instrument Air Systems were added to the Systems Section. Finally, High Containment Hydrogen Concentration and Plant Fire On Site evolutions added to the Emergency and Abnormal Plant Evolutions section.

  15. Colorado State University Program for developing, testing, evaluating and optimizing solar heating and cooling systems. Project status report, August--September 1994

    SciTech Connect

    Hittle, D.C.

    1994-11-01

    The current work has been to validate Florida Solar Energy Center`s models of the Solahart 302K and 302K-AS systems to prepare a rating for the Sacramento Municipal Utility District`s rebate program for solar domestic hot water heaters.

  16. Calculations of fluid-mineral equilibria in the Aspo Hard Rock Laboratory

    SciTech Connect

    Bruton, C.J.

    1995-05-01

    The purpose of this report is to evaluate the utility of the EQ3/6 geochemical codes in describing mineral-fluid equilibria in the low temperature (<25{degrees}C) systems at the Aespoe Hard Rock Laboratory (HRL). Data on fluid chemistry and on fracture-filling mineralogy with depth were obtained from Smellie and Laaksoharju. Average temperatures in the HRL boreholes are generally less than 20{degrees}C. EQ3/6 was used to evaluate the extent to which equilibrium is achieved between minerals and fluids in these systems. Smellie and Laaksoharju used the PHREEQE geochemical modeling code to calculate saturation indices for fracture-lining minerals in boreholes KAS02, KAS03, KAS04 and KAS06 in order to ``support the presence or absence of the major fracture minerals``. They noted that only calcite and gypsum may be expected to attain equilibrium under the low temperature conditions Aespoe. However, they used closeness to equilibrium as an indicator of ``stable conditions, long bedrock residence/reaction times and slow to stagnant flow in the system.`` EQ3 was used to calculate mineral saturation indices for comparison, and EQ6 was used to try to predict the mineral assemblages coexisting with fluids.

  17. 10 CFR 26.29 - Training.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Training. 26.29 Section 26.29 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Program Elements § 26.29 Training. (a) Training content. Licensees and other entities shall ensure that the individuals who are subject to this subpart have the following KAs...

  18. 10 CFR 26.29 - Training.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Training. 26.29 Section 26.29 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Program Elements § 26.29 Training. (a) Training content. Licensees and other entities shall ensure that the individuals who are subject to this subpart have the following KAs...

  19. 10 CFR 26.29 - Training.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Training. 26.29 Section 26.29 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Program Elements § 26.29 Training. (a) Training content. Licensees and other entities shall ensure that the individuals who are subject to this subpart have the following KAs...

  20. 10 CFR 26.29 - Training.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Training. 26.29 Section 26.29 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Program Elements § 26.29 Training. (a) Training content. Licensees and other entities shall ensure that the individuals who are subject to this subpart have the following KAs...

  1. 10 CFR 26.29 - Training.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Training. 26.29 Section 26.29 Energy NUCLEAR REGULATORY COMMISSION FITNESS FOR DUTY PROGRAMS Program Elements § 26.29 Training. (a) Training content. Licensees and other entities shall ensure that the individuals who are subject to this subpart have the following KAs...

  2. Surface acidity of 2:1-type dioctahedral clay minerals from first principles molecular dynamics simulations

    NASA Astrophysics Data System (ADS)

    Liu, Xiandong; Cheng, Jun; Sprik, Michiel; Lu, Xiancai; Wang, Rucheng

    2014-09-01

    We report a first principles molecular dynamics (FPMD) study of the acid chemistry of 2:1-type dioctahedral phyllosilicates. Using the FPMD based vertical energy gap method, we computed intrinsic acidity constants of phyllosilicate edge sites. The investigated models include both neutral and charged frameworks (i.e., Mg for Al replacement in octahedral sheets and Al for Si replacement in tetrahedral sheets) and the common edge surface types (i.e., (0 1 0) and (1 1 0)). The result of the neutral framework agrees with the experiment of pyrophyllite. For charged frameworks, it is found that tbnd Al(OH) sites in T-sheets (i.e., Al-sub) and tbnd Mg(OH2) sites (i.e., Mg-sub) have extremely high pKas and thus they all keep protonated. Both types of substitutions increase pKas of the apical oxygen sites on (1 1 0) surfaces and Mg substitution also increases the pKas of neighboring silanol sites. With the calculated pKas, we explore the mechanism of heavy metal cations complexation on edge surfaces. As a quantitative basis, the results in this work can be used in future modeling and experimental studies for understanding acid reactivity of phyllosilicates.

  3. Privatization of Peacekeeping: UN’s Institutional Capacity to Control Private Military and Security Companies

    DTIC Science & Technology

    2013-09-01

    SAS (Special Air Service, founded by David Stirling ) and its successors (WatchGuard in 1967, Kulinda Security Ltd. 1970s, KAS Enterprises 1986) as... engineering equipment, accommodation and ablution units—for rapid deployment to new peacekeeping operations. The role of Brindisi was expanded to include

  4. Electrostatics of cysteine residues in proteins: Parameterization and validation of a simple model

    PubMed Central

    Salsbury, Freddie R.; Poole, Leslie B.; Fetrow, Jacquelyn S.

    2013-01-01

    One of the most popular and simple models for the calculation of pKas from a protein structure is the semi-macroscopic electrostatic model MEAD. This model requires empirical parameters for each residue to calculate pKas. Analysis of current, widely used empirical parameters for cysteine residues showed that they did not reproduce expected cysteine pKas; thus, we set out to identify parameters consistent with the CHARMM27 force field that capture both the behavior of typical cysteines in proteins and the behavior of cysteines which have perturbed pKas. The new parameters were validated in three ways: (1) calculation across a large set of typical cysteines in proteins (where the calculations are expected to reproduce expected ensemble behavior); (2) calculation across a set of perturbed cysteines in proteins (where the calculations are expected to reproduce the shifted ensemble behavior); and (3) comparison to experimentally determined pKa values (where the calculation should reproduce the pKa within experimental error). Both the general behavior of cysteines in proteins and the perturbed pKa in some proteins can be predicted reasonably well using the newly determined empirical parameters within the MEAD model for protein electrostatics. This study provides the first general analysis of the electrostatics of cysteines in proteins, with specific attention paid to capturing both the behavior of typical cysteines in a protein and the behavior of cysteines whose pKa should be shifted, and validation of force field parameters for cysteine residues. PMID:22777874

  5. Urea-, thiourea-, and guanidine-linked glycooligomers as phosphate binders in water.

    PubMed

    Jiménez Blanco, José L; Bootello, Purificación; Benito, Juan M; Mellet, Carmen Ortiz; García Fernandez, José M

    2006-07-07

    Beta-(1-->6)-linked pseudodi- and pseudotrisaccharides incorporating alternating pseudoamide-type (urea, thiourea, guanidine) intersaccharide bridges have been prepared and evaluated as phosphate binders in water. The monosaccharide subunits induce the Z,Z rotameric form at the pseudoamide segments, thus favoring their participation in bidentate hydrogen-bond interactions with oxoanions. Moreover, the conformational properties about the anomeric C-1-N bonds and the sugar C-5--C-6 bonds privilege orientations that facilitate both the desolvation of the incoming anionic guest and the stabilization of the complex by cooperative interactions. Measurable association constants (K(as)) toward dimethyl and, especially, phenyl phosphate were obtained from NMR titration experiments for both series of glucooligomers, the binding affinity being strongly dependent on the nature of the pseudoamide functionality. Guanidinium derivatives, for which charge neutralization was expected to contribute to phosphate binding, were superior to the neutral thiourea and urea derivatives (K(as) = 48-60 M(-1) for 1:1 complexes with phenyl phosphate dianion). Interestingly, the thiourea oligomers exhibited association constants of the same order of magnitude (K(as) = 25-40 M(-1)), much higher than those observed for the urea analogues (K(as) = 2-3 M(-1)), which is ascribed to a less efficient solvation of the thiocarbonyl derivatives.

  6. Kohn anomalies and nonadiabaticity in doped carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Caudal, Nicolas; Saitta, A. Marco; Lazzeri, Michele; Mauri, Francesco

    2007-03-01

    The high-frequency Raman-active phonon modes of metallic single-walled carbon nanotubes (SWCNT) are thought to be characterized by Kohn anomalies (KAs) resulting from the combination of SWCNT intrinsic one-dimensional nature and a significant electron-phonon coupling (EPC). KAs are expected to be modified by the doping-induced tuning of the Fermi energy level γF , obtained through the intercalation of SWCNTs with alkali atoms or by the application of a gate potential. We present a density-functional theory (DFT) study of the phonon properties of a (9,9) metallic SWCNT as a function of electronic doping. For such study, we use, as in standard DFT calculations of vibrational properties, the Born-Oppenheimer (BO) approximation. We also develop an analytical model capable of reproducing and interpreting our DFT results. Both DFT calculations and this model predict, for increasing doping levels, a series of EPC-induced KAs in the vibrational mode parallel to the tube axis at the Γ point of the Brillouin zone, usually indicated in Raman spectroscopy as the G- peak. Such KAs would arise each time a new conduction band is populated. However, we show that they are an artifact of the BO approximation. The inclusion of nonadiabatic effects dramatically affects the results, predicting KAs at Γ only when γF is close to a band crossing EX . For each band crossing, a double KA occurs for γF=EX±ℏω/2 , where ℏω is the phonon energy. In particular, for a 1.2nm metallic nanotube, we predict a KA to occur in the so-called G- peak at a doping level of about Nel/C=±0.0015 atom (γF≈±0.1eV) and, possibly, close to the saturation doping level (Nel/ Ctilde 0.125) , where an interlayer band crosses the π* nanotube bands. Furthermore, we predict that the Raman linewidth of the G- peak significantly decreases for ∣γF∣⩾ℏω/2 . Thus, our results provide a tool to determine experimentally the doping level from the value of the KA-induced frequency shift and from the

  7. Clinico-morphological features of BRAF inhibition-induced proliferative skin lesions in cancer patients.

    PubMed

    Belum, Viswanath Reddy; Rosen, Alyx C; Jaimes, Natalia; Dranitsaris, George; Pulitzer, Melissa P; Busam, Klaus J; Marghoob, Ashfaq A; Carvajal, Richard D; Chapman, Paul B; Lacouture, Mario E

    2015-01-01

    The use of BRAF inhibitors may lead to the development of cutaneous toxicities such as rashes, photosensitivity, alopecia, palmoplantar erythrodysesthesia, and proliferative skin lesions, including keratoacanthomas (KAs) and cutaneous squamous cell carcinomas (cuSCCs). The latter are noteworthy for their potential to exhibit malignant features, and they may necessitate invasive treatment. Their prompt identification is of primary importance for directing supportive care efforts and maintaining dose intensity while minimizing the morbidity associated with supportive care interventions. Because such lesions are less familiar to oncologists, this study was designed to characterize their clinico-morphological features, which have not been hitherto described. The clinical and dermoscopic characteristics and risk factors of new-onset proliferative skin lesions (benign verrucous lesions and KAs/cuSCCs) developing after the initiation of treatment with vemurafenib, dabrafenib, and XL281 were analyzed; the histopathological diagnoses were ascertained. The majority of the lesions were benign verrucous lesions (78%, n = 87), whereas KAs/cuSCCs represented 22% (n = 25). The median times to biopsy for the initial verrucous lesions and KAs/cuSCCs were 4.8 and 10.5 weeks, respectively. The clinico-morphological features significant for KAs/cuSCCs included a larger size (P < .001), a nodular appearance (P < .001), a central keratin plug (P < .001), a central ulceration or crust (P = .04), an adherent scale (P = .02), an erythematous halo (P = .03), and a scaly ring (collarette; P < .001) at the periphery. Our findings represent the first detailed description of the clinico-morphological characteristics that permit distinction between the benign and malignant skin lesions induced by BRAF inhibitors. They are valuable for the recognition of lesions that require intervention and/or a dermatology referral versus those that permit provisional

  8. The role of social support and social networks in health information-seeking behavior among Korean Americans: a qualitative study.

    PubMed

    Kim, Wonsun; Kreps, Gary L; Shin, Cha-Nam

    2015-04-28

    This study used social network theory to explore the role of social support and social networks in health information-seeking behavior among Korean American (KA) adults. A descriptive qualitative study using a web-based online survey was conducted from January 2013 to April 2013 in the U.S. The survey included open-ended questions about health information-seeking experiences in personal social networks and their importance in KA adults. Themes emerging from a constant comparative analysis of the narrative comments by 129 of the 202 respondents were analyzed. The sample consisted of 129 KA adults, 64.7% female, with a mean age of 33.2 (SD = 7.7). Friends, church members, and family members were the important network connections for KAs to obtain health information. KAs looked for a broad range of health information from social network members, from recommendations and reviews of hospitals/doctors to specific diseases or health conditions. These social networks were regarded as important for KAs because there were no language barriers, social network members had experiences similar to those of other KAs, they felt a sense of belonging with those in their networks, the network connections promoted increased understanding of different health care systems of the U.S. system, and communication with these network connections helped enhance feelings of being physically and mentally healthy. This study demonstrates the important role that social support and personal social networks perform in the dissemination of health information for a large ethnic population, KAs, who confront distinct cultural challenges when seeking health information in the U.S. Data from this study also illustrate the cultural factors that influence health information acquisition and access to social support for ethnic minorities. This study provides practical insights for professionals in health information services, namely, that social networks can be employed as a channel for disseminating

  9. Targeting the IL-6 pathway in multiple myeloma and its implications in cancer-associated gene hypermethylation.

    PubMed

    Ingersoll, Susan Blaydes; Ahmad, Sarfraz; Thoni, Natalie D; Ahmed, Farhana H; Monahan, Kimberly A; Edwards, John R

    2011-09-01

    Aberrant methylation of tumor suppressor genes (TSG) is an important epigenetic event in cancer, including multiple myeloma (MM). Interleukin-6 (IL-6), which plays a significant role in the pathogenesis of MM, also regulates DNA methylation. However, attempts to bring IL-6 blockade to the clinic have had limited success. We hypothesize that IL-6 regulation of hypermethylation may be an important pathway leading to rational chemotherapeutic/anti-IL-6 combinations. We first studied the correlation of IL-6 expression and dependence in MM cell lines: U266B1, RPMI8226, and KAS6/1. We confirmed that KAS6/1 is IL-6-dependent whereas U266B1 and RPMI8226 cells are IL-6-independent and that blocking IL-6 inhibited the growth of U266B1 (36% inhibition; p<0.05) and KAS6/1 (68% inhibition; p<0.01), but not the RPMI8226 cells. Using RT-PCR, we showed that U266B1 cells express IL-6, but RPMI8226 and KAS6/1 cells do not. This IL-6 expression pattern correlates with the anti-IL-6 inhibition findings. To correlate IL-6 sensitivity with hypermethylation of TSG, we investigated promoter methylation of CDH1 and DcR1. We found that the promoter of DcR1 and CDH1 is methylated in U266B1 cells and un-methylated in RPMI8226 cells. Furthermore, the DcR1 promoter was un-methylated in KAS6/1 cells. These data support our hypothesis that an IL-6-dependent pathway may regulate hypermethylation of TSG in MM. Newer chemotherapeutic agents that affect methylation are being studied in combination with IL-6 blockade.

  10. Chirality-Induced Dynamic Kohn Anomalies in Graphene

    NASA Astrophysics Data System (ADS)

    Tse, Wang-Kong; Hu, Ben Yu-Kuang; Das Sarma, S.

    2008-08-01

    We develop a theory for the renormalization of the phonon energy dispersion in graphene due to the combined effects of both Coulomb and electron-phonon (e-ph) interactions. We obtain the renormalized phonon energy spectrum by an exact analytic derivation of the phonon self-energy, finding three distinct Kohn anomalies (KAs) at the phonon wave vector q=ω/v, 2kF±ω/v for LO phonons and one at q=ω/v for TO phonons. The presence of these new KAs in graphene, in contrast to the usual KA q=2kF in ordinary metals, originates from the dynamical screening of e-ph interaction (with a concomitant breakdown of the Born-Oppenheimer approximation) and the peculiar chirality of the graphene e-ph coupling.

  11. Thermal degradation studies and kinetic modeling of cardoon (Cynara cardunculus) pyrolysis using thermogravimetric analysis (TGA).

    PubMed

    Damartzis, Th; Vamvuka, D; Sfakiotakis, S; Zabaniotou, A

    2011-05-01

    A key element in the design of sustainable pyrolysis processes is the thermal degradation kinetics of biomass. In this work, pyrolysis tests for cardoon (Cynara carduculus) stems and leaves were performed in a non-isothermal thermogravimetric analyzer (TGA) in order to determine the thermal degradation behavior of both stems and leaves. The kinetic parameters of the process were evaluated using three different kinetic models, the independent parallel reaction model, KAS and OFW iso-conversional model. Good agreement with the experimental TGA data was observed for all models, the best being with the independent parallel reaction model. A variance in the activation energy with conversion was observed when the KAS and OFW models were employed, which reveals that the pyrolysis of cardoon progresses through more complex and multi-step kinetics.

  12. p Ka calculation of poliprotic acid: histamine

    NASA Astrophysics Data System (ADS)

    De Abreu, Heitor A.; De Almeida, Wagner B.; Duarte, Hélio A.

    2004-01-01

    Various theoretical studies have been reported addressing the performance of solvation models available to estimate p Ka values. However, no attention has been paid so far to the role played by the electronic, thermal and solvation energy individual contributions to the Gibbs free energy of the deprotonation process. In this work, we decompose the total Gibbs free energy into three distinct terms and then evaluate the dependence of each contribution on the level of theory employed for its determination using different levels of theory. The three possible p Kas of histamine have been estimated and compared with available experimental data. We found that the electronic energy term is sensitive to the level of theory and basis set, and, therefore, could be also a source of error in the theoretical calculation of p Kas.

  13. Nonisothermal Thermogravimetric Analysis of Thai Lignite with High CaO Content

    PubMed Central

    Pintana, Pakamon

    2013-01-01

    Thermal behaviors and combustion kinetics of Thai lignite with different SO3-free CaO contents were investigated. Nonisothermal thermogravimetric method was carried out under oxygen environment at heating rates of 10, 30, and 50°C min−1 from ambient up to 1300°C. Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods were adopted to estimate the apparent activation energy (E) for the thermal decomposition of these coals. Different thermal degradation behaviors were observed in lignites with low (14%) and high (42%) CaO content. Activation energy of the lignite combustion was found to vary with the conversion fraction. In comparison with the KAS method, higher E values were obtained by the FWO method for all conversions considered. High CaO lignite was observed to have higher activation energy than the low CaO coal. PMID:24250259

  14. OPTN/SRTR 2015 Annual Data Report: Early effects of the new kidney allocation system

    PubMed Central

    Hart, A.; Gustafson, S. K.; Skeans, M. A.; Stock, P.; Stewart, D.; Kasiske, B.L.; Israni, A. K.

    2017-01-01

    In December 2014, a new kidney allocation system (KAS) was implemented in the United States in an attempt to improve access to transplant for historically underrepresented groups, and to incorporate longevity matching such that donor kidneys with the longest projected graft survival are given to recipients with the longest projected patient survival. The development of organ allocation policies is often guided by simulated allocation models, computer programs that simulate the arrival of donated organs and new candidates on the waiting list over a 1-year period to project outcomes under a new allocation method. We examined the early outcomes under the new KAS using quarterly data beginning in 2013, revealing whether trends were already underway before implementation. Quarterly data also serve to reveal any bolus effect, or a rapid rise or fall in the proportion of transplants in a given group due to reordering of the list, followed by tapering toward a new steady state. Post-KAS changes were notable for an increase in the proportion of transplants among younger candidates, black and Hispanic candidates, highly sensitized candidates, and those on dialysis for at least 5 years. Transplants among blood type B candidates increased slightly but these candidates remain underrepresented relative to their prevalence on the waiting list. Regional and national sharing increased under the new KAS, but transplants of kidneys with a kidney donor profile index above 85% decreased. Early graft survival appears unchanged, but given the increases in regional sharing, cold ischemia time, and transplants among highly sensitized candidates and candidates with long pretransplant dialysis time, long-term graft survival will need to monitored. PMID:28052605

  15. Acidity of edge surface sites of montmorillonite and kaolinite

    NASA Astrophysics Data System (ADS)

    Liu, Xiandong; Lu, Xiancai; Sprik, Michiel; Cheng, Jun; Meijer, Evert Jan; Wang, Rucheng

    2013-09-01

    Acid-base chemistry of clay minerals is central to their interfacial properties, but up to now a quantitative understanding on the surface acidity is still lacking. In this study, with first principles molecular dynamics (FPMD) based vertical energy gap technique, we calculate the acidity constants of surface groups on (0 1 0)-type edges of montmorillonite and kaolinite, which are representatives of 2:1 and 1:1-type clay minerals, respectively. It shows that tbnd Si-OH and tbnd Al-OH2OH groups of kaolinite have pKas of 6.9 and 5.7 and those of montmorillonite have pKas of 7.0 and 8.3, respectively. For each mineral, the calculated pKas are consistent with the experimental ranges derived from fittings of titration curves, indicating that tbnd Si-OH and tbnd Al-OH2OH groups are the major acidic sites responsible to pH-dependent experimental observations. The effect of Mg substitution in montmorillonite is investigated and it is found that Mg substitution increases the pKas of the neighboring tbnd Si-OH and tbnd Si-OH2 groups by 2-3 pKa units. Furthermore, our calculation shows that the pKa of edge tbnd Mg-(OH2)2 is as high as 13.2, indicating the protonated state dominates under common pH. Together with previous adsorption experiments, our derived acidity constants suggest that tbnd Si-O- and tbnd Al-(OH)2 groups are the most probable edge sites for complexing heavy metal cations.

  16. ONR (Office of Naval Research) Far East Scientific Information Bulletin. Volume 13, Number 4, October-December 1988

    DTIC Science & Technology

    1988-12-01

    billion. Net income \\kas S5() million. ONRFI" SCI INFO B’I., 13 (4) 88 20 must be solved, Japanese researchers are 5. B.D. Cullity, Elements of X - Rayo ...are important characteristics of this technology tanw fer pwcess. Research and Applications of Metallic Superlattices, High T, Superconductors, X -Ray...superconductors, and x -ray optics and also reports on the development of compact synchrotrons for generation of soft- x - rays. Kuroshio Exploitation and

  17. What’s in a Wiki? Using Collaborative Technology for Developing, Reviewing and Publishing the Systems Engineering Body of Knowledge (SEBoK)

    DTIC Science & Technology

    2012-07-01

    al. 2004) and the Project Management Body of Knowledge ( PMBOK ™) (PMI 2008). However, these prototype versions, which was believed to contain only a...must have some level of stability; this is seen in the SWBOK and PMBOK , which are updated after a period of several years. Finally, it was determined...knowledge areas (KAs). “Knowledge Area” is a term commonly found in bodies of knowledge (e.g. the SWEBOK and PMBOK ™) that is used as an organizational

  18. Neomycin resistance as a selectable marker in Methanococcus maripaludis

    SciTech Connect

    Argyle, J.L.; Leigh, J.A.; Tumbula, D.L.

    1996-11-01

    The authors cloned the aminoglycoside phosphotransferase genes APH3{prime}I and APH3{prime}II between the Methanococcus voltae methyl reductase promoter and terminator in a plasmid containing a fragment of Methanococcus maripaludis chromosomal DNA. The resulting plasmids encoding neomycin resistance transformed M. maripaludis at frequencies similar to those observed for pKAS102 encoding puromycin resistance. The antibiotic geneticin was not inhibitory to M. maripaludis. 22 refs., 3 figs., 3 tabs.

  19. Metagenomic Analysis of the Sponge Discodermia Reveals the Production of the Cyanobacterial Natural Product Kasumigamide by ‘Entotheonella’

    PubMed Central

    Nakashima, Yu; Egami, Yoko; Kimura, Miki; Wakimoto, Toshiyuki; Abe, Ikuro

    2016-01-01

    Sponge metagenomes are a useful platform to mine cryptic biosynthetic gene clusters responsible for production of natural products involved in the sponge-microbe association. Since numerous sponge-derived bioactive metabolites are biosynthesized by the symbiotic bacteria, this strategy may concurrently reveal sponge-symbiont produced compounds. Accordingly, a metagenomic analysis of the Japanese marine sponge Discodermia calyx has resulted in the identification of a hybrid type I polyketide synthase-nonribosomal peptide synthetase gene (kas). Bioinformatic analysis of the gene product suggested its involvement in the biosynthesis of kasumigamide, a tetrapeptide originally isolated from freshwater free-living cyanobacterium Microcystis aeruginosa NIES-87. Subsequent investigation of the sponge metabolic profile revealed the presence of kasumigamide in the sponge extract. The kasumigamide producing bacterium was identified as an ‘Entotheonella’ sp. Moreover, an in silico analysis of kas gene homologs uncovered the presence of kas family genes in two additional bacteria from different phyla. The production of kasumigamide by distantly related multiple bacterial strains implicates horizontal gene transfer and raises the potential for a wider distribution across other bacterial groups. PMID:27732651

  20. Korean American women's perceptions about physical examinations and cancer screening services offered in Korea: the influences of medical tourism on Korean Americans.

    PubMed

    Oh, Kyeung Mi; Jun, Jungmi; Zhou, Qiuping; Kreps, Gary

    2014-04-01

    Cancer is the leading cause of death for Korean-Americans (KAs), while cancer screening rates among KAs have been consistently low. Seven semi-structured focus group interviews with 34 KA women aged 40 or older in the Washington, DC metropolitan area were conducted to explore the perceptions of KA women about seeking physical examinations and cancer screening services in Korea. Data were analyzed using a framework approach. Informants positively perceived the use of health screening services in Korea in comparison to seeking such services in the US. Decision-making factors included cost benefits, high quality services, and more convenient screening procedures in Korea. These benefits outweighed the risks of delaying health care and travelling a vast distance with incurring additional travel costs. Motivations to seek these services in Korea included opportunities to visit their homeland and to enjoy comfortable communication with their native language. The increase of available information about Korean medical services due to the industry's aggressive marketing/PR was identified as a facilitator. Most informants did not recognize possible negative health outcomes of obtaining services in Korea such as inappropriate follow up care if having abnormal findings. Educational programs are needed to educate KAs about the benefits and risks of getting the services in Korea and proper follow up care in the US. Health care providers need to know the different cancer risks and screening needs for this population.

  1. Thermal Degradation of Flame Retarded Polyvinylchloride Cable Sheath in Air Atmosphere

    NASA Astrophysics Data System (ADS)

    Zhang, Jiaqing; Wang, Liufang; Fan, Minghao; Xie, Hui; Li, Wei; Wang, Shuping

    2017-05-01

    A series of thermogravimetric experiments from 10 K/min to 50 K/min was performed to analyse the pyrolysis behaviours and reaction kinetics of typical old flame-retarded PVC cable sheath in air atmosphere. Two model-free methods of Flynn-Wall-Ozawa (FWO) method and Kissinger-Akahira-Sunose (KAS) method were used to estimate the activation energy, as well as the model-fitting method called Coats-Redfern (CR) method. Three peaks can be observed in mass loss rate profiles and the first peak value is much larger than the other two. Due to the oxidation of carbon or others, the first and third peak values in air atmosphere are significantly larger, and the final residue mass fraction in air atmosphere is around 62% the one in Nitrogen atmosphere. FWO method predicts the activation energy of 223.1kJ/mol while KAS model estimates the one of 223.7kJ/mol in air atmosphere, and both have the deviation of 0.27%. By CR method, the most probable reaction mechanism is [1 - (1 - α)-2]/(- 2) for current fire retarded PVC cable sheath. Moreover, it estimates the activation energy of 237.6 kJ/mol, which is well agreeable with those from FWO and KAS methods.

  2. Affinity study on bovine serum albumin's peptides to amphiphilic gold nanoparticles: A test of epitopes and non-epitopes

    NASA Astrophysics Data System (ADS)

    Yuan, Ming; Li, Wanrong; Yang, Mingming; Huang, Xiufeng; Bai, Zhijun; Liu, Yushuang; Cai, Weijun; Wang, Yuqin; Zhang, Feng

    2017-09-01

    It is an inevitable event that nanoparticles (NPs) will encounter proteins/peptides in nano-medicine, so it has been significant to know their interaction mechanism before in vivo applications. Previously, a 105-amino-acid sequence had been reported as the binding site between bovine serum albumin (BSA) and amphiphilic polymer coated gold nanoparticles (AP-AuNPs) along with a mortise-tenon joint hypothesis. This article tested the affinity difference between two epitope peptide sequences such as: LGEYGFQNALIVR (S1), DAFLGSFLYEYSR (S2) and one non-epitope peptide sequence as: FDEHVKLVNELTEF (S3). With the photoluminescent amino acid residues, the fluorescence quenching method based on the nanometal surface energy transfer (NSET) principle was able to study the thermodynamics of the current binding system. The binding constants (Ka) were determined and followed the order as: Ka-S1 > Ka-S2 >> Ka-S3. Moreover, Hill constants indicated that cooperativity only presented in the interactions of AP-AuNP with either S1 or S2, but not for S3. Moreover, gel electrophoresis, surface plasmon resonance, atomic force microscopy and three dimensional fluorescence microscopy were all also used to comprehensively analyse the binding interaction mechanism. These results further provided useful information to better understand the mortise-tenon joint, which might find applications to nanofabrication and biomedicine.

  3. Enhancing cytokine-induced killer cell therapy of multiple myeloma.

    PubMed

    Liu, Chunsheng; Suksanpaisan, Lukkana; Chen, Yun-Wen; Russell, Stephen J; Peng, Kah-Whye

    2013-06-01

    Cytokine-induced killer (CIK) cells are in clinical testing against various tumor types, including multiple myeloma. In this study, we show that CIK cells have activity against subcutaneous and disseminated models of human myeloma (KAS-6/1), which can be enhanced by infecting the CIK cells with an oncolytic measles virus (MV) or by pretreating the myeloma cells with ionizing radiation (XRT). KAS-6/1 cells were killed by coculture with CIK or MV-infected CIK (CIK/MV) cells, and the addition of an anti-NKG2D antibody inhibited cytolysis by 50%. However, human bone marrow stromal cells can reduce CIK and CIK/MV mediated killing of myeloma cells (RPMI 8226, JJN-3 and MM1). In vivo, CIK and CIK/MV prolonged the survival of mice with systemic myeloma, although CIK/MV showed enhanced antitumor activity compared with CIK. Irradiation of the KAS-6/1 cells induced mRNA and protein expression of NKG2D ligands, MICA, and MICB in a dose-dependent manner and enhanced delivery of CIK/MV to the irradiated tumors. In both subcutaneous and disseminated myeloma models, XRT at 2 Gy resulted in superior prolongation of the survival of mice given CIK/MV therapy compared with CIK/MV with no XRT. This study demonstrates the potential of CIK against myeloma and that the combination of virotherapy with radiation could be used to further enhance therapeutic outcome using CIK cells.

  4. Korean-Americans’ Knowledge about Depression and Attitudes about Treatment Options

    PubMed Central

    Kim, Eunjung; Im, Eun-Ok

    2017-01-01

    The purpose of this pilot study was to explore first-generation Korean-Americans’ knowledge about depression and attitudes about depression treatment options. Self-report survey data were gathered from 73 first-generation Korean-Americans (KAs) using instruments developed for this study. The data were analyzed using descriptive and inferential statistics including t-tests. Data indicated participants lacked knowledge about depression. Among all depression treatment options, exercise was the option that first-generation KAs were most willing to try and was rated as having the least shame attached to it. Taking an antidepressant was the option KAs reported being most unwilling to try and had the highest shame attached to it. No significant differences in knowledge about depression and attitudes about depression treatment options were found between low and high acculturation groups, with the exception that the high acculturation group demonstrated more agreement than the low acculturation group with the item that emotional symptoms, such as mood changes, can be depression symptoms. These results suggest that initiating depression treatment with exercise may be the most acceptable starting point in treating depression in first-generation KA immigrants. PMID:26241572

  5. Polyhydroxyalkanoates (PHA) biosynthesis from kraft mill wastewaters: biomass origin and C:N relationship influence.

    PubMed

    Pozo, G; Villamar, A C; Martínez, M; Vidal, G

    2011-01-01

    The goal of this study is to evaluate the feasibility of PHA biosynthesis from kraft mill effluent using the batch system evaluating the biomass origin and C:N relationship influence. To evaluate feasibility, batch assays were carried out. Also, two levels of the BOD5:N:P relationship (100:5:1 and 100:1:0.2) and three different sludge origins were considered. Inocula were obtained from activated sludge treatment plants for a) sewage (SAS), b) paper mill (PAS) and c) kraft (KAS). The results show that the maximum Biological Oxygen Demand (BOD5) and Chemical Oxygen Demand (COD) removal was 80.5% and 59.7% respectively using KAS as inoculum. In these assays, kinetics constants were 17.9±3.2 mg L(-1) and 46.5±1.2 d(-1) for (KCOD) and (rmax), respectively under a BOD5:N:P relationship of 100:5:1. The maximum PHA accumulation was obtained under a BOD5:N:P relationship of 100:1:0.2 on the third day of batch assays using PAS sludge with 25.72% of the cells accumulating PHA and on the fifth day in batch using SAS and KAS sludge with 25.85% and 30.40% of cells accumulating PHA, respectively. Yields obtained for the 100:1:0.2 relationships ranged from 0.10-0.14 mg PHA mg(-1) COD.

  6. Geomorphology and age of the Marocche di Dro rock avalanches (Trentino, Italy)

    NASA Astrophysics Data System (ADS)

    Ivy-Ochs, S.; Martin, S.; Campedel, P.; Hippe, K.; Alfimov, V.; Vockenhuber, C.; Andreotti, E.; Carugati, G.; Pasqual, D.; Rigo, M.; Viganò, A.

    2017-08-01

    The Marocche di Dro deposits in the lower Sarca Valley are some of the most distinctive rock avalanche deposits of the Alps. We use geomorphology and cosmogenic 36Cl exposure dating of boulders to divide the Marocche di Dro deposits into two rock avalanche bodies; the Marocca Principale to the north and the Kas to the south. The deposits were previously undated and had been mapped as up to five different events. The largest event Marocca Principale, which comprises an estimated 1000 106 m3 of predominantly Rotzo Formation limestones, occurred 5300 ± 860 yr ago. The release area is located mainly in the alcove between Mt. Casale and Mt. Granzoline, but likely extends all the way to Mt. Brento. The Kas event took place 1080 ± 160 yr ago with detachment below Mt. Brento. The Kas debris, with an estimated volume of 300 106 m3, buried the southern third of the Marocca Principale deposit. Kas presents a barren, stark landscape dominated by house-sized Tovel Member Rotzo Formation boulders bearing distinctive chert lenses. Both the extreme relief of the rock wall (more than 1300 m) and the tectonic setting predispose the range front to massive failure. For the two events, initially translational movement likely quickly evolved into complex failure and massive collapse. Run-out across the valley of several kilometers and run-up on the opposite slope of hundreds of meters followed. A summary of all dated and large historical landslides in the Alps underlines the periods of enhanced slope activity discussed in the literature: 10-9 kyr, 5-3 kyr, and 2-1 kyr, the latter especially for the Southern Alps. No deposits of the first temporal cluster are found at Marocche di Dro. The age of Marocca Principale at 5300 ± 860 yr suggests occurrence during the second period. Failure may have been related to the shift to wetter, colder climate at the transition from the middle to the late Holocene. Nevertheless, a seismic trigger cannot be ruled out. For the Kas rock avalanche at 1080

  7. Improved training tolerance by supplementation with α-Keto acids in untrained young adults: a randomized, double blind, placebo-controlled trial

    PubMed Central

    2012-01-01

    Background Exercise causes a variety of physiological and metabolic changes that can in turn reduce exercise tolerance. One of the potential mechanisms responsible for fatigue is “exercise-induced hyperammonemia”. Previous studies have shown that supplementation with amino acids can increase training tolerance. The α-keto acids are biochemical analogs of amino acids and can be converted to amino acids through transamination, thus reducing the cellular ammonia level. This double blind, placebo-controlled study was designed to investigate the effects of α-keto acid supplementation (KAS) on training tolerance, training effect, and stress-recovery state. Methods Thirty-three untrained young male adults underwent four weeks of training (5 sessions/week; 30 minutes running at the individual anaerobic threshold followed by 3 x 3 minute sprints/each session). Throughout the 4 weeks of training and one week of recovery, subjects took α-ketoglutarate (AKG group, 0.2 g/kg/d, n = 9), branched-chain keto acids (BCKA group, 0.2 g/kg/d, n = 12) or isocaloric placebo (control group, n = 12) daily. Results The 4th week training volume, maximum power output and muscle torque were higher in the AKG group (175 ± 42 min, 412 ± 49 Watts and 293 ± 58 Newton meters, respectively, P<0.05) and the BCKA group (158 ± 35, 390 ± 29 and 273 ± 47, P<0.05) than in the control group (92 ± 70, 381 ± 67 and 233 ± 43). The general stress and emotional exhaustion as assessed by the rest-stress-questionnaire-sport after the 3rd week of training increased significantly in the control group (P<0.05), but not in the KAS groups. Conclusions Under KAS, subjects could bear a higher training volume and reach a higher power output and peak muscle torque, accompanied by a better stress-recovery-state. Thus, KAS improves exercise tolerance and training effects along with a better stress-recovery state. Whether the improved training tolerance

  8. An arsenate-reducing and alkane-metabolizing novel bacterium, Rhizobium arsenicireducens sp. nov., isolated from arsenic-rich groundwater.

    PubMed

    Mohapatra, Balaram; Sarkar, Angana; Joshi, Swati; Chatterjee, Atrayee; Kazy, Sufia Khannam; Maiti, Mrinal Kumar; Satyanarayana, Tulasi; Sar, Pinaki

    2017-03-01

    A novel arsenic (As)-resistant, arsenate-respiring, alkane-metabolizing bacterium KAs 5-22(T), isolated from As-rich groundwater of West Bengal was characterized by physiological and genomic properties. Cells of strain KAs 5-22(T) were Gram-stain-negative, rod-shaped, motile, and facultative anaerobic. Growth occurred at optimum of pH 6.0-7.0, temperature 30 °C. 16S rRNA gene affiliated the strain KAs 5-22(T) to the genus Rhizobium showing maximum similarity (98.4 %) with the type strain of Rhizobium naphthalenivorans TSY03b(T) followed by (98.0 % similarity) Rhizobium selenitireducens B1(T). The genomic G + C content was 59.4 mol%, and DNA-DNA relatedness with its closest phylogenetic neighbors was 50.2 %. Chemotaxonomy indicated UQ-10 as the major quinone; phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol as major polar lipids; C16:0, C17:0, 2-OH C10:0, 3-OH C16:0, and unresolved C18:1 ɷ7C/ɷ9C as predominant fatty acids. The cells were found to reduce O2, As(5+), NO3(-), SO4(2-) and Fe(3+) as alternate electron acceptors. The strain's ability to metabolize dodecane or other alkanes as sole carbon source using As(5+) as terminal electron acceptor was supported by the presence of genes encoding benzyl succinate synthase (bssA like) and molybdopterin-binding site (mopB) of As(5+) respiratory reductase (arrA). Differential phenotypic, chemotaxonomic, genotypic as well as physiological properties revealed that the strain KAs 5-22(T) is separated from its nearest recognized Rhizobium species. On the basis of the data presented, strain KAs 5-22(T) is considered to represent a novel species of the genus Rhizobium, for which the name Rhizobium arsenicireducens sp. nov. is proposed as type strain (=LMG 28795(T)=MTCC 12115(T)).

  9. Characterization of Sea Lettuce Surface Functional Groups by Potentiometric Titrations

    NASA Astrophysics Data System (ADS)

    Ebling, A. M.; Schijf, J.

    2008-12-01

    In pursuit of our ultimate goal to better understand the prodigious capacity of the marine macroalga Ulva lactuca (sea lettuce) for adsorbing a broad range of dissolved trace metals from seawater, we performed an initial characterization of its surface functional groups. Specifically, the number of distinct functional groups as well as their individual bulk concentrations and acid dissociation constants (pKas) were determined by potentiometric titrations in NaCl solutions of various ionic strengths (I = 0.01-5.0 M), under inert nitrogen atmosphere at 25°C. Depending on the ionic strength, Ulva samples were manually titrated down to pH 2 or 3 with 1 N HCl and then up to pH 10 with 1 N NaOH in steps of 0.1-0.2 units, continuously monitoring pH with a glass combination electrode. Titrations of a dehydrated Ulva standard reference material (BCR-279) were compared with fresh Ulva tissue cultured in our laboratory. A titration in filtered natural seawater was also compared with one in an NaCl solution of equal ionic strength. Equilibrium constants for the ionization of water in NaCl solutions as a function of ionic strength were obtained from the literature. Fits to the titration data ([H]T vs. pH) were performed with the FITEQL4.0 computer code using non-electrostatic 3-, 4-, and 5-site models, either by fixing ionic strength at its experimental value or by allowing it to be extrapolated to zero, while considering all functional group pKas and bulk concentrations as adjustable parameters. Since pKas and bulk concentrations were found to be strongly correlated, the latter were also fixed in some cases to further constrain the pKas. Whereas these calculations are currently ongoing, preliminary results point to three, possibly four, functional groups with pKas of about 4.1, 6.3, and 9.5 at I = 0. Bulk concentrations of the three groups are very similar, about 5-6×10-4 mol/g based on dry weight, which suggests that all are homogeneously distributed over the surface and

  10. The ASCENT (Allocation System Changes for Equity in Kidney Transplantation) Study: a Randomized Effectiveness-Implementation Study to Improve Kidney Transplant Waitlisting and Reduce Racial Disparity.

    PubMed

    Patzer, Rachel E; Smith, Kayla; Basu, Mohua; Gander, Jennifer; Mohan, Sumit; Escoffery, Cam; Plantinga, Laura; Melanson, Taylor; Kalloo, Sean; Green, Gary; Berlin, Alex; Renville, Gary; Browne, Teri; Turgeon, Nicole; Caponi, Susan; Zhang, Rebecca; Pastan, Stephen

    2017-05-01

    The United Network for Organ Sharing (UNOS) implemented a new Kidney Allocation System (KAS) in December 2014 that is expected to substantially reduce racial disparities in kidney transplantation among waitlisted patients. However, not all dialysis facility clinical providers and end stage renal disease (ESRD) patients are aware of how the policy change could improve access to transplant. We describe the ASCENT (Allocation System Changes for Equity in KidNey Transplantation) study, a randomized controlled effectiveness-implementation study designed to test the effectiveness of a multicomponent intervention to improve access to the early steps of kidney transplantation among dialysis facilities across the United States. The multicomponent intervention consists of an educational webinar for dialysis medical directors, an educational video for patients and an educational video for dialysis staff, and a dialysis-facility specific transplant performance feedback report. Materials will be developed by a multidisciplinary dissemination advisory board and will undergo formative testing in dialysis facilities across the United States. This study is estimated to enroll ~600 U.S. dialysis facilities with low waitlisting in all 18 ESRD Networks. The co-primary outcomes include change in waitlisting, and waitlist disparity at 1 year; secondary outcomes include changes in facility medical director knowledge about KAS, staff training regarding KAS, patient education regarding transplant, and a medical director's intent to refer patients for transplant evaluation. The results from the ASCENT study will demonstrate the feasibility and effectiveness of a multicomponent intervention designed to increase access to the deceased-donor kidney waitlist and reduce racial disparities in waitlisting.

  11. New Insights Into the Alleged Kidney Donor Profile Index Labeling Effect on Kidney Utilization.

    PubMed

    Stewart, D E; Garcia, V C; Aeder, M I; Klassen, D K

    2017-10-01

    The Kidney Donor Profile Index (KDPI) became a driving factor in deceased donor kidney allocation on December 4, 2014, with the implementation of the kidney allocation system (KAS). On April 20, 2016, the annual recalibration of the Kidney Donor Risk Index into KDPI was incorrectly programmed in DonorNet, resulting in erroneously high KDPI values, by between 1 and 21 percentage points (e.g. actual KDPI of 70% was displayed as 86%). The error was corrected on May 19, 2016, <24 h after being recognized. During this 30-day period, the distribution of recipients largely resembled pre-KAS patterns. The observed discard rate of 22.9% was higher than the post-KAS average of 19.6% (odds ratio [OR]: 1.22) but far lower than the projected rate of 31.4% (OR: 1.96) based on the usual discard rate by KDPI relationship, suggesting clinicians and patients did not rely heavily on this single number (KDPI) in kidney-utilization decisions. Still, risk-adjusted analyses suggest the elevated discard rate was most likely attributable to the erroneously high KDPIs, not a shift in donor characteristics or random chance. The rise in discard rate was sharply higher for kidneys with inflated KDPI that crossed the 85% policy threshold (OR: 1.46; p = 0.049) versus those that did not (OR: 1.06; p = 0.631). © 2017 The American Society of Transplantation and the American Society of Transplant Surgeons.

  12. Fatty Acid Biosynthesis in Pseudomonas aeruginosa Is Initiated by the FabY Class of β-Ketoacyl Acyl Carrier Protein Synthases

    PubMed Central

    Yuan, Yanqiu; Sachdeva, Meena; Leeds, Jennifer A.

    2012-01-01

    The prototypical type II fatty acid synthesis (FAS) pathway in bacteria utilizes two distinct classes of β-ketoacyl synthase (KAS) domains to assemble long-chain fatty acids, the KASIII domain for initiation and the KASI/II domain for elongation. The central role of FAS in bacterial viability and virulence has stimulated significant effort toward developing KAS inhibitors, particularly against the KASIII domain of the β-acetoacetyl-acyl carrier protein (ACP) synthase FabH. Herein, we show that the opportunistic pathogen Pseudomonas aeruginosa does not utilize a FabH ortholog but rather a new class of divergent KAS I/II enzymes to initiate the FAS pathway. When a P. aeruginosa cosmid library was used to rescue growth in a fabH downregulated strain of Escherichia coli, a single unannotated open reading frame, PA5174, complemented fabH depletion. While deletion of all four KASIII domain-encoding genes in the same P. aeruginosa strain resulted in a wild-type growth phenotype, deletion of PA5174 alone specifically attenuated growth due to a defect in de novo FAS. Siderophore secretion and quorum-sensing signaling, particularly in the rhl and Pseudomonas quinolone signal (PQS) systems, was significantly muted in the absence of PA5174. The defect could be repaired by intergeneric complementation with E. coli fabH. Characterization of recombinant PA5174 confirmed a preference for short-chain acyl coenzyme A (acyl-CoA) substrates, supporting the identification of PA5174 as the predominant enzyme catalyzing the condensation of acetyl coenzyme A with malonyl-ACP in P. aeruginosa. The identification of the functional role for PA5174 in FAS defines the new FabY class of β-ketoacyl synthase KASI/II domain condensation enzymes. PMID:22753059

  13. Gain of 11q/cyclin D1 overexpression is an essential early step in skin cancer development and causes abnormal tissue organization and differentiation.

    PubMed

    Burnworth, B; Popp, S; Stark, H-J; Steinkraus, V; Bröcker, E B; Hartschuh, W; Birek, C; Boukamp, P

    2006-07-27

    Non-melanoma skin cancers, in particular keratoacanthomas (KAs) and squamous cell carcinomas (SCCs), have become highly frequent tumor types especially in immune-suppressed transplant patients. Nevertheless, little is known about essential genetic changes. As a paradigm of 'early' changes, that is, changes still compatible with tumor regression, we studied KAs by comparative genomic hybridization and show that gain of chromosome 11q is not only one of the most frequent aberration (8/18), but in four tumors also the only aberration. Furthermore, 11q gain correlated with amplification of the cyclin D1 locus (10/14), as determined by fluorescence in situ hybridization, and overexpression of cyclin D1 protein (25/31), as detected by immunohistochemistry. For unraveling the functional consequence, we overexpressed cyclin D1 in HaCaT skin keratinocytes. These cells only gained little growth advantage in conventional and in organotypic co-cultures. However, although the control vector-transfected cells formed a well-stratified and orderly differentiated epidermis-like epithelium, they showed deregulation of tissue architecture with an altered localization of proliferation and impaired differentiation. The most severe phenotype was seen in a clone that additionally upregulated cdk4 and p21. These cells lacked terminal differentiation, exhibited a more autonomous growth in vitro and in vivo and even formed tumors in two injection sites with a growth pattern resembling that of human KAs. Thus, our results identify 11q13 gain/cyclin D1 overexpression as an important step in KA formation and point to a function that exceeds its known role in proliferation by disrupting tissue organization and thereby allowing abnormal growth.

  14. Psychometrics of Shared Decision Making and Communication as Patient Centered Measures for Two Language Groups

    PubMed Central

    Alvarez, Kiara; Wang, Ye; Alegria, Margarita; Ault-Brutus, Andrea; Ramanayake, Natasha; Yeh, Yi-Hui; Jeffries, Julia R.; Shrout, Patrick E.

    2017-01-01

    Shared decision-making (SDM) and effective patient-provider communication are key and interrelated elements of patient-centered care that impact health and behavioral health outcomes. Measurement of SDM and communication from the patient’s perspective is necessary in order to ensure that health care systems and individual providers are responsive to patient views. However, there is a void of research addressing the psychometric properties of these measures with diverse patients, including non-English speakers, and in the context of behavioral health encounters. This study evaluated the psychometric properties of two patient-centered outcome measures, the Shared Decision Making Questionnaire-9 (SDM-Q) and the Kim Alliance Scale-Communication Subscale (KAS-CM), in a sample of 239 English and Spanish-speaking behavioral health patients. One dominant factor was found for each scale and this structure was used to examine whether there was measurement invariance across the two language groups. One SDM-Q item was inconsistent with the configural invariance comparison and was removed. The remaining SDM-Q items exhibited strong invariance, meaning that item loadings and item means were similar across the two groups. The KAS-CM items had limited variability, with most respondents indicating high communication levels, and the invariance analysis was done on binary versions of the items. These had metric invariance (loadings the same over groups) but several items violated the strong invariance test. In both groups, the SDM-Q had high internal consistency, whereas the KAS-CM was only adequate. These findings help interpret results for individual patients, taking into account cultural and linguistic differences in how patients perceive SDM and patient-provider communication. PMID:27537002

  15. Signature Gene Expression Profiles Discriminate between Isoniazid-, Thiolactomycin-, and Triclosan-Treated Mycobacterium tuberculosis

    PubMed Central

    Betts, Joanna C.; McLaren, Alistair; Lennon, Mark G.; Kelly, Fiona M.; Lukey, Pauline T.; Blakemore, Steve J.; Duncan, Ken

    2003-01-01

    Genomic technologies have the potential to greatly increase the efficiency of the drug development process. As part of our tuberculosis drug discovery program, we used DNA microarray technology to profile drug-induced effects in Mycobacterium tuberculosis. Expression profiles of M. tuberculosis treated with compounds that inhibit key metabolic pathways are required as references for the assessment of novel antimycobacterial agents. We have studied the response of M. tuberculosis to treatment with the mycolic acid biosynthesis inhibitors isoniazid, thiolactomycin, and triclosan. Thiolactomycin targets the β-ketoacyl-acyl carrier protein (ACP) synthases KasA and KasB, while triclosan inhibits the enoyl-ACP reductase InhA. However, controversy surrounds the precise mode of action of isoniazid, with both InhA and KasA having been proposed as the primary target. We have shown that although the global response profiles of isoniazid and thiolactomycin are more closely related to each other than to that of triclosan, there are differences that distinguish the mode of action of these two drugs. In addition, we have identified two groups of genes, possibly forming efflux and detoxification systems, through which M. tuberculosis may limit the effects of triclosan. We have developed a mathematical model, based on the expression of 21 genes, which is able to perfectly discriminate between isoniazid-, thiolactomycin-, or triclosan-treated M. tuberculosis. This model is likely to prove invaluable as a tool to improve the efficiency of our drug development programs by providing a means to rapidly confirm the mode of action of thiolactomycin analogues or novel InhA inhibitors as well as helping to translate enzyme activity into whole-cell activity. PMID:12936993

  16. Quantum Chemical Benchmarking, Validation, and Prediction of Acidity Constants for Substituted Pyridinium Ions and Pyridinyl Radicals.

    PubMed

    Keith, John A; Carter, Emily A

    2012-09-11

    Sensibly modeling (photo)electrocatalytic reactions involving proton and electron transfer with computational quantum chemistry requires accurate descriptions of protonated, deprotonated, and radical species in solution. Procedures to do this are generally nontrivial, especially in cases that involve radical anions that are unstable in the gas phase. Recently, pyridinium and the corresponding reduced neutral radical have been postulated as key catalysts in the reduction of CO2 to methanol. To assess practical methodologies to describe the acid/base chemistry of these species, we employed density functional theory (DFT) in tandem with implicit solvation models to calculate acidity constants for 22 substituted pyridinium cations and their corresponding pyridinyl radicals in water solvent. We first benchmarked our calculations against experimental pyridinium deprotonation energies in both gas and aqueous phases. DFT with hybrid exchange-correlation functionals provide chemical accuracy for gas-phase data and allow absolute prediction of experimental pKas with unsigned errors under 1 pKa unit. The accuracy of this economical pKa calculation approach was further verified by benchmarking against highly accurate (but very expensive) CCSD(T)-F12 calculations. We compare the relative importance and sensitivity of these energies to selection of solvation model, solvation energy definitions, implicit solvation cavity definition, basis sets, electron densities, model geometries, and mixed implicit/explicit models. After determining the most accurate model to reproduce experimentally-known pKas from first principles, we apply the same approach to predict pKas for radical pyridinyl species that have been proposed relevant under electrochemical conditions. This work provides considerable insight into the pitfalls using continuum solvation models, particularly when used for radical species.

  17. HBV-Related Health Behaviors in a Socio-Cultural Context: Perspectives from Khmers and Koreans

    PubMed Central

    Lee, Haeok; Kiang, Peter; Chea, Phala; Peou, Sonith; Tang, Shirley S.; Yang, JinHwang; Fawcett, Jacqueline; Hann, Hie-Won

    2014-01-01

    Purpose To explore factors influencing health and health care within the sociocultural context of Cambodian Americans (CAs or Khmers) and Korean Americans (KA) and to examine intergroup similarities and differences between CAs and KAs, focusing on hepatitis B virus (HBV) and liver cancer prevention behaviors. Methods The study used a qualitative design guided by the revised Network Episode Model (NEM) and informed by ethnographic analysis. Focus group interviews with key informants among CA community health leaders (CHLs, n=14) and individual interviews with key informants of KA CHLs (n=9) were audiotaped and transcribed. Results Three categories that influenced HBV and liver cancer prevention emerged from both CAs and KAs: the socio-cultural, individual, and behavioral. Four additional sub-categories (sub-themes) of sociocultural were identified as socio-history, socio-medicine, socio-linguistic, and socio-health resources. Both CAs and KAs, however, have low levels of knowledge and significant misunderstandings about HBV infection. Conclusions The study identifies and compares the social-cultural determinant for HBV and liver cancer and highlights the factors of education, intercultural communication, and interactions within socio-cultural contexts of CA and KA subgroups. In general, conceptual overlaps are apparent between Khmers (from now on, the terms, CA and Khmer, will be used interchangeably) and Koreans except for the sub-theme of socio-history. However, differences in concept-specific attributes point to the need to account for differing conceptualizations and implications of specific ethnic groups’ sociocultural contexts, and to design contextually-relevant outreach and educational interventions for targeted AAPI subgroups. PMID:24355416

  18. The voltage-dependent step of the chloride transporter of Valonia utricularis encounters a Nernst-Planck and not an Eyring type of potential energy barrier

    PubMed Central

    Wang, Jianning; Zimmermann, Ulrich; Benz, Roland

    1993-01-01

    Voltage-clamp experiments were performed on cells of the giant marine alga Valonia utricularis to study the voltage dependence of the previously postulated chloride transporter (Wang, J., G. Wehner, R. Benz, and U. Zimmermann. 1991. Biophys. J. 59:235-248). Only one exponential current relaxation (apart from the capacitive spike) could be resolved up to a clamp voltage of ∼120 mV within the time resolution of our experimental instrumentation (100 μs). This means that the rate constants of the heterogeneous complexation, kR (association) and kD (dissociation), were too fast to be resolved. Therefore, the “Läuger” model for carrier-mediated ion transport with equilibrium heterogeneous surface reaction was used to fit the experimental results. The voltage dependence of the initial membrane conductance was used for the evaluation of the voltage dependence of the translocation rate constant of the complexed carriers, kAS. The initial conductance was found to be independent on the clamp voltage, which means that the translocation rate constant kAS is a linear function of the applied voltage and that the voltage dependence of the translocation of charged carriers through the plasmalemma could be explained by a square-type Nernst-Planck barrier. The movement of the complexed form of the carrier through the membrane may be explained by a diffusion process rather than by simple first-order kinetic jump across an Eyring-type potential well. The current relaxation after a voltage clamp was studied as a function of the external chloride concentration. The results allowed an estimation of the stability constant, K, of the heterogeneous complexation reaction and a calculation of the translocation rate constants of the free and the complexed carriers, ks and kAS, respectively. PMID:19431881

  19. Population Genetics Study of Isoniazid Resistance Mutations and Evolution of Multidrug-Resistant Mycobacterium tuberculosis†

    PubMed Central

    Hazbón, Manzour Hernando; Brimacombe, Michael; Bobadilla del Valle, Miriam; Cavatore, Magali; Guerrero, Marta Inírida; Varma-Basil, Mandira; Billman-Jacobe, Helen; Lavender, Caroline; Fyfe, Janet; García-García, Lourdes; León, Clara Inés; Bose, Mridula; Chaves, Fernando; Murray, Megan; Eisenach, Kathleen D.; Sifuentes-Osornio, José; Cave, M. Donald; Ponce de León, Alfredo; Alland, David

    2006-01-01

    The molecular basis for isoniazid resistance in Mycobacterium tuberculosis is complex. Putative isoniazid resistance mutations have been identified in katG, ahpC, inhA, kasA, and ndh. However, small sample sizes and related potential biases in sample selection have precluded the development of statistically valid and significant population genetic analyses of clinical isoniazid resistance. We present the first large-scale analysis of 240 alleles previously associated with isoniazid resistance in a diverse set of 608 isoniazid-susceptible and 403 isoniazid-resistant clinical M. tuberculosis isolates. We detected 12 mutant alleles in isoniazid-susceptible isolates, suggesting that these alleles are not involved in isoniazid resistance. However, mutations in katG, ahpC, and inhA were strongly associated with isoniazid resistance, while kasA mutations were associated with isoniazid susceptibility. Remarkably, the distribution of isoniazid resistance-associated mutations was different in isoniazid-monoresistant isolates from that in multidrug-resistant isolates, with significantly fewer isoniazid resistance mutations in the isoniazid-monoresistant group. Mutations in katG315 were significantly more common in the multidrug-resistant isolates. Conversely, mutations in the inhA promoter were significantly more common in isoniazid-monoresistant isolates. We tested for interactions among mutations and resistance to different drugs. Mutations in katG, ahpC, and inhA were associated with rifampin resistance, but only katG315 mutations were associated with ethambutol resistance. There was also a significant inverse association between katG315 mutations and mutations in ahpC or inhA and between mutations in kasA and mutations in ahpC. Our results suggest that isoniazid resistance and the evolution of multidrug-resistant strains are complex dynamic processes that may be influenced by interactions between genes and drug-resistant phenotypes. PMID:16870753

  20. Preoperative Patellofemoral Chondromalacia is Not a Contraindication for Fixed-Bearing Medial Unicompartmental Knee Arthroplasty.

    PubMed

    Adams, Alexander J; Kazarian, Gregory S; Lonner, Jess H

    2017-06-01

    Patellofemoral chondromalacia (PFCM) has historically been considered a contraindication for unicompartmental knee arthroplasty (UKA), but there is limited data assessing PFCM's impact on the results of fixed-bearing UKA. Our objective was to assess the impact of medial patellar and/or medial trochlear PFCM on overall and patellofemoral-specific 2-year outcomes after fixed-bearing medial UKA. Intraoperative notes defined the presence and location of PFCM during fixed bearing medial UKA. Outcome measures included the New Knee Society Score (NKSS), Kneeling Ability Score (KAS) and Forgotten Joint Score (FJS-12). Thirty-one knees with PFCM (PFCM group), and 52 knees without PFCM (N-PFCM group) were included for analysis. Mann-Whitney U tests assessed the statistical significance of observed differences, and a Bonferroni correction was applied, adjusting threshold for significance to P = .005. At minimum follow-up of 2 years, no statistical differences were detected between the N-PFCM and PFCM groups in the postoperative NKSS (159 vs 157, P = .731), preoperative to postoperative NKSS change (P = .447), FJS-12 (70.5 vs 67.6, P = .471), or KAS (71% vs 65%, P = .217). Patients with isolated patellar chondromalacia (n = 13) demonstrated trends toward worse outcomes according to NKSS (147, P = .198), FJS-12 (58, P = .094), and KAS (46%, P = .018), but were statistically insignificant. No failures occurred in either group. Functional outcomes of fixed-bearing medial UKA are not adversely impacted by the presence of PFCM involving the medial patellar facet and/or medial or central trochlea. Further follow-up is needed to determine longer-term implications of fixed-bearing medial UKA in patients with PFCM. Copyright © 2017 Elsevier Inc. All rights reserved.

  1. Decarboxylation of malonyl-(acyl carrier protein) by 3-oxoacyl-(acyl carrier protein) synthases in plant fatty acid biosynthesis.

    PubMed Central

    Winter, E; Brummel, M; Schuch, R; Spener, F

    1997-01-01

    In order to identify regulatory steps in fatty acid biosynthesis, the influence of intermediate 3-oxoacyl-(acyl carrier proteins) (3-oxoacyl-ACPs) and end-product acyl-ACPs of the fatty acid synthase reaction on the condensation reaction was investigated in vitro, using total fatty acid synthase preparations and purified 3-oxoacyl-ACP synthases (KASs; EC 2.3.1.41) from Cuphea lanceolata seeds. KAS I and II in the fatty acid synthase preparations were assayed for the elongation of octanoyl- and hexadecanoyl-ACP respectively, and the accumulation of the corresponding condensation product 3-oxoacyl-ACP was studied by modulating the content of the reducing equivalentS NADH and NADPH. Complete omission of reducing equivalents resulted with either KAS in the abnormal synthesis of acetyl-ACP from malonyl-ACP by a decarboxylation reaction. Supplementation with NADPH or NADH, separately or in combination with recombinant 3-oxoacyl-ACP reductase (EC 1.1.1.100), led to a decrease in the amount of acetyl-ACP and a simultaneous increase in elongation products. This demonstrates that the accumulation of 3-oxoacyl-ACP inhibits the condensation reaction on the one hand, and induces the decarboxylation of malonyl-ACP on the other. By carrying out similar experiments with purified enzymes, this decarboxylation was attributed to the action of KAS. Our data point to a regulatory mechanism for the degradation of malonyl-ACP in plants which is activated by the accumulation of the fatty acid synthase intermediate 3-oxoacyl-ACP. PMID:9020860

  2. Electrostatic effects in macromolecules: fundamental concepts and practical modeling.

    PubMed

    Warshel, A; Papazyan, A

    1998-04-01

    The past few years have seen an exponential growth in the calculations of electrostatic energies of macromolecules and an increased recognition of the crucial role of electrostatic effects. This review considers the current state of the field. Focus is placed on calculations of pKas, redox potentials and binding energies in macromolecules and clarification of the fact that the value of the dielectric 'constant' of a protein depends on its definition and that small dielectric constants should not be used in describing charge-charge interactions by current continuum models.

  3. Growth and Doping of SiC-Thin Films on Low-Stress, Amorphous Si3N4/Si Substrates for Robust Microelectromechanical Systems Applications

    DTIC Science & Technology

    2002-01-01

    111) peak as a function of 3MS flow rate. Growth temperature: 1200°C, and N2 flow rate: 1 sccm. Fig. 5. Resistivity and sheet resistance of SiC films...at 300 K as a function of growth temperature. Flow rates: 30 sccm 3MS and 1 sccm N2. Fig. 6. Resistivity and sheet resistance of SiC films at 300 K...as a function of 3MS flow rate. Growth temperature: 1200°C, and N2 flow rate: 1 sccm. Fig. 7. Resistivity and sheet resistance of SiC films at 300 K as

  4. Colorado State University program for developing, testing, evaluating and optimizing solar heating and cooling systems: Project status report for the months of October and November, 1994

    SciTech Connect

    Not Available

    1994-12-01

    This report describes a project to develop tools for evaluating solar heating and cooling systems. Current work on this project has been to validate the Florida Solar Energy Center`s (FSEC) models of the Solahart 302K and 302K-AS systems to prepare a rating for the Sacramento Municipal Utility District`s rebate program for solar domestic hot water heaters. A preliminary rating has been issued by FSEC and updated ratings will be released as necessary. Two of the problems that were mentioned in the August/September report are addressed and a tank heat loss test is discussed. Work continues on improving and validating the models.

  5. Development of a next-generation NIL library in Arabidopsis thaliana for dissecting complex traits.

    PubMed

    Fletcher, Richard S; Mullen, Jack L; Yoder, Seth; Bauerle, William L; Reuning, Gretchen; Sen, Saunak; Meyer, Eli; Juenger, Thomas E; McKay, John K

    2013-09-25

    The identification of the loci and specific alleles underlying variation in quantitative traits is an important goal for evolutionary biologists and breeders. Despite major advancements in genomics technology, moving from QTL to causal alleles remains a major challenge in genetics research. Near-isogenic lines are the ideal raw material for QTL validation, refinement of QTL location and, ultimately, gene discovery. In this study, a population of 75 Arabidopsis thaliana near-isogenic lines was developed from an existing recombinant inbred line (RIL) population derived from a cross between physiologically divergent accessions Kas-1 and Tsu-1. First, a novel algorithm was developed to utilize genome-wide marker data in selecting RILs fully isogenic to Kas-1 for a single chromosome. Seven such RILs were used in 2 generations of crossing to Tsu-1 to create BC1 seed. BC1 plants were genotyped with SSR markers so that lines could be selected that carried Kas-1 introgressions, resulting in a population carrying chromosomal introgressions spanning the genome. BC1 lines were genotyped with 48 genome-wide SSRs to identify lines with a targeted Kas-1 introgression and the fewest genomic introgressions elsewhere. 75 such lines were selected and genotyped at an additional 41 SNP loci and another 930 tags using 2b-RAD genotyping by sequencing. The final population carried an average of 1.35 homozygous and 2.49 heterozygous introgressions per line with average introgression sizes of 5.32 and 5.16 Mb, respectively. In a simple case study, we demonstrate the advantage of maintaining heterozygotes in our library whereby fine-mapping efforts are conducted simply by self-pollination. Crossovers in the heterozygous interval during this single selfing generation break the introgression into smaller, homozygous fragments (sub-NILs). Additionally, we utilize a homozygous NIL for validation of a QTL underlying stomatal conductance, a low heritability trait. The present results introduce a

  6. Translation and validation of the dietary approaches to stop hypertension for koreans intervention: culturally tailored dietary guidelines for Korean Americans with high blood pressure.

    PubMed

    Kim, Hyerang; Song, Hee-Jung; Han, Hae-Ra; Kim, Kim B; Kim, Miyong T

    2013-01-01

    Lifestyle modification strategies such as adoption of the Dietary Approaches to Stop Hypertension (DASH) diet are now recognized as an integral part of high blood pressure (HBP) management. Although the high prevalence of HBP among Korean Americans (KAs) is well documented, few dietary interventions have been implemented in this population, in part because of a lack of culturally relevant nutrition education guidelines. Translating and testing the efficacy of culturally relevant dietary recommendations using a well-established dietary guideline such as DASH are imperative for promoting better cardiovascular health for this high-risk cultural group. The aims of this study were to systematically translate and validate a culturally modified DASH for Koreans (K-DASH) and obtain preliminary evidence of efficacy. A 2-step approach of intervention translation and efficacy testing, together with close adherence to principles of community-based participatory research, was used to maximize community input. A 1-group pre-post design with 24-hour urine and 24-hour ambulatory blood pressure monitoring comparisons was used to test the initial feasibility and efficacy of the K-DASH intervention. A total of 28 KAs with HBP participated in a 10-week dietary intervention consisting of group education sessions and individual counseling. Both systolic blood pressure and diastolic blood pressure, as measured by ambulatory blood pressure monitoring, were significantly decreased at postintervention evaluation (systolic blood pressure, -4.5 mm Hg; diastolic blood pressure, -2.6 mm Hg; P < .05). Serum low-density lipoprotein cholesterol was significantly decreased (-7.3 mg/dL; P < .05). Serum potassium and ascorbic acid levels were also improved in the reference range. Urine potassium level was significantly increased, supporting increased fruit and vegetable consumption. This pilot study has (a) demonstrated that a cultural adaptation of DASH using community-based participatory research

  7. Development of a next-generation NIL library in Arabidopsis thaliana for dissecting complex traits

    PubMed Central

    2013-01-01

    Background The identification of the loci and specific alleles underlying variation in quantitative traits is an important goal for evolutionary biologists and breeders. Despite major advancements in genomics technology, moving from QTL to causal alleles remains a major challenge in genetics research. Near-isogenic lines are the ideal raw material for QTL validation, refinement of QTL location and, ultimately, gene discovery. Results In this study, a population of 75 Arabidopsis thaliana near-isogenic lines was developed from an existing recombinant inbred line (RIL) population derived from a cross between physiologically divergent accessions Kas-1 and Tsu-1. First, a novel algorithm was developed to utilize genome-wide marker data in selecting RILs fully isogenic to Kas-1 for a single chromosome. Seven such RILs were used in 2 generations of crossing to Tsu-1 to create BC1 seed. BC1 plants were genotyped with SSR markers so that lines could be selected that carried Kas-1 introgressions, resulting in a population carrying chromosomal introgressions spanning the genome. BC1 lines were genotyped with 48 genome-wide SSRs to identify lines with a targeted Kas-1 introgression and the fewest genomic introgressions elsewhere. 75 such lines were selected and genotyped at an additional 41 SNP loci and another 930 tags using 2b-RAD genotyping by sequencing. The final population carried an average of 1.35 homozygous and 2.49 heterozygous introgressions per line with average introgression sizes of 5.32 and 5.16 Mb, respectively. In a simple case study, we demonstrate the advantage of maintaining heterozygotes in our library whereby fine-mapping efforts are conducted simply by self-pollination. Crossovers in the heterozygous interval during this single selfing generation break the introgression into smaller, homozygous fragments (sub-NILs). Additionally, we utilize a homozygous NIL for validation of a QTL underlying stomatal conductance, a low heritability trait. Conclusions

  8. Histidine in Continuum Electrostatics Protonation State Calculations

    PubMed Central

    Couch, Vernon; Stuchebruckhov, Alexei

    2014-01-01

    A modification to the standard continuum electrostatics approach to calculate protein pKas which allows for the decoupling of histidine tautomers within a two state model is presented. Histidine with four intrinsically coupled protonation states cannot be easily incorporated into a two state formalism because the interaction between the two protonatable sites of the imidazole ring is not purely electrostatic. The presented treatment, based on a single approximation of the interrelation between histidine’s charge states, allows for a natural separation of the two protonatable sites associated with the imidazole ring as well as the inclusion of all protonation states within the calculation. PMID:22072521

  9. Thermal analysis of magnesium reactions with nitrogen/oxygen gas mixtures.

    PubMed

    Chunmiao, Yuan; Lifu, Yu; Chang, Li; Gang, Li; Shengjun, Zhong

    2013-09-15

    The thermal behavior and kinetic parameters of magnesium powder subjected to a nitrogen-rich atmosphere was investigated in thermogravimetric (TG) and differential scanning calorimeter (DSC) experiments with oxygen/nitrogen mixtures heated at rates of 5, 10, 15, and 20 °C/min. At higher temperature increase rates, the observed oxidation or nitridation steps shifted toward higher temperatures. The comparison of mass gain and heat of reaction in different nitrogen concentrations is helpful in interpreting the inerting effect of nitrogen on magnesium powder explosion in closed vessels. Activation energies for oxidation in air calculated by the Kissinger-Akahira-Sunose (KAS) method are generally consistent with previously published reports, but the method was not successful for the entire nitridation process. The change of activation energy with temperature was related to protective properties of the corresponding coating layer at particle surfaces. Two main coating layer growth processes were found in magnesium oxidation and nitridation using a modified Dreizin method which was also employed to determine activation energy for both magnesium oxidation and nitridation. For magnesium powder oxidation, activation energy calculated by the Dreizin method was close to that by KAS. Variation in activation energies was a function of different mechanisms inherent in the two methods.

  10. Computational Tools for Interpreting Ion Channel pH-Dependence.

    PubMed

    Sazanavets, Ivan; Warwicker, Jim

    2015-01-01

    Activity in many biological systems is mediated by pH, involving proton titratable groups with pKas in the relevant pH range. Experimental analysis of pH-dependence in proteins focusses on particular sidechains, often with mutagenesis of histidine, due to its pKa near to neutral pH. The key question for algorithms that predict pKas is whether they are sufficiently accurate to effectively narrow the search for molecular determinants of pH-dependence. Through analysis of inwardly rectifying potassium (Kir) channels and acid-sensing ion channels (ASICs), mutational effects on pH-dependence are probed, distinguishing between groups described as pH-coupled or pH-sensor. Whereas mutation can lead to a shift in transition pH between open and closed forms for either type of group, only for pH-sensor groups does mutation modulate the amplitude of the transition. It is shown that a hybrid Finite Difference Poisson-Boltzmann (FDPB) - Debye-Hückel continuum electrostatic model can filter mutation candidates, providing enrichment for key pH-coupled and pH-sensor residues in both ASICs and Kir channels, in comparison with application of FDPB alone.

  11. Non-isothermal pyrolysis of de-oiled microalgal biomass: Kinetics and evolved gas analysis.

    PubMed

    Maurya, Rahulkumar; Ghosh, Tonmoy; Saravaia, Hitesh; Paliwal, Chetan; Ghosh, Arup; Mishra, Sandhya

    2016-12-01

    Non-isothermal (β=5, 10, 20, 35°C/min) pyrolysis of de-oiled microalgal biomass (DMB) of Chlorella variabilis was investigated by TGA-MS (30-900°C, Argon atmosphere) to understand thermal decomposition and evolved gas analysis (EGA). The results showed that three-stage thermal decomposition and three volatilization zone (100-400°C, 400-550°C and 600-750°C) of organic matters during pyrolysis. The highest rate of weight-loss is 8.91%/min at 302°C for 35°C/min heating-rate. Kinetics of pyrolysis were investigated by iso-conversional (KAS, FWO) and model-fitting (Coats-Redfern) method. For Zone-1and3, similar activation energy (Ea) is found in between KAS (α=0.4), FWO (α=0.4) and Avrami-Erofe'ev (n=4) model. Using the best-fitted kinetic model Avrami-Erofe'ev (n=4), Ea values (R(2)=>0.96) are 171.12 (Zone-1), 404.65 (Zone-2) and 691.42kJ/mol (Zone-3). EGA indicate the abundance of most gases observed consequently between 200-300°C and 400-500°C. The pyrolysis of DMB involved multi-step reaction mechanisms for solid-state reactions having different Ea values. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Computational Tools for Interpreting Ion Channel pH-Dependence

    PubMed Central

    Sazanavets, Ivan; Warwicker, Jim

    2015-01-01

    Activity in many biological systems is mediated by pH, involving proton titratable groups with pKas in the relevant pH range. Experimental analysis of pH-dependence in proteins focusses on particular sidechains, often with mutagenesis of histidine, due to its pKa near to neutral pH. The key question for algorithms that predict pKas is whether they are sufficiently accurate to effectively narrow the search for molecular determinants of pH-dependence. Through analysis of inwardly rectifying potassium (Kir) channels and acid-sensing ion channels (ASICs), mutational effects on pH-dependence are probed, distinguishing between groups described as pH-coupled or pH-sensor. Whereas mutation can lead to a shift in transition pH between open and closed forms for either type of group, only for pH-sensor groups does mutation modulate the amplitude of the transition. It is shown that a hybrid Finite Difference Poisson-Boltzmann (FDPB) – Debye-Hückel continuum electrostatic model can filter mutation candidates, providing enrichment for key pH-coupled and pH-sensor residues in both ASICs and Kir channels, in comparison with application of FDPB alone. PMID:25915903

  13. Identification of Gene-Specific Polymorphisms and Association with Capsaicin Pathway Metabolites in Capsicum annuum L. Collections

    PubMed Central

    Abburi, Venkata L.; Alaparthi, Suresh Babu; Unselt, Desiree; Hankins, Gerald; Park, Minkyu; Choi, Doil

    2014-01-01

    Pepper (Capsicum annuum L.) is an economically important crop with added nutritional value. Production of capsaicin is an important quantitative trait with high environmental variance, so the development of markers regulating capsaicinoid accumulation is important for pepper breeding programs. In this study, we performed association mapping at the gene level to identify single nucleotide polymorphisms (SNPs) associated with capsaicin pathway metabolites in a diverse Capsicum annuum collection during two seasons. The genes Pun1, CCR, KAS and HCT were sequenced and matched with the whole-genome sequence draft of pepper to identify SNP locations and for further characterization. The identified SNPs for each gene underwent candidate gene association mapping. Association mapping results revealed Pun1 as a key regulator of major metabolites in the capsaicin pathway mainly affecting capsaicinoids and precursors for acyl moieties of capsaicinoids. Six different SNPs in the promoter sequence of Pun1 were found associated with capsaicin in plants from both seasons. Our results support that CCR is an important control point for the flux of p-coumaric acid to specific biosynthesis pathways. KAS was found to regulate the major precursors for acyl moieties of capsaicinoids and may play a key role in capsaicinoid production. Candidate gene association mapping of Pun1 suggested that the accumulation of capsaicinoids depends on the expression of Pun1, as revealed by the most important associated SNPs found in the promoter region of Pun1. PMID:24475113

  14. The Role of p16, p21, p27, p53 and Ki-67 Expression in the Differential Diagnosis of Cutaneous Squamous Cell Carcinomas and Keratoacanthomas: An Immunohistochemical Study

    PubMed Central

    Bedir, Recep; Güçer, Hasan; Şehitoğlu, İbrahim; Yurdakul, Cüneyt; Bağcı, Pelin; Üstüner, Pelin

    2016-01-01

    Background: Distinguishing squamous cell carcinoma (SCC) from keratoacanthoma (KA) by histopathological features may not be sufficient for a differential diagnosis, as KAs may, in some cases, imitate well-differentiated SCCs. Aims: In this study, we investigated whether the expression of the p16, p21, p27, p53 genes and a Ki-67 proliferation index are useful in distinguishing between these two tumors. Study Design: Cross-sectional study. Methods: Immunohistochemistry was used to investigate the expression of the p16, p21, p27, p53 genes and the Ki-67 proliferation index was investigated in well-differentiated SCC with KA-like features (n=40) and KA (n=30). Results: The results of all of the examined markers, except for p27 (p16, p21, p53, and Ki-67) were found to be significantly different between the SCC and KA samples (p<0.05). Conclusion: In well-differentiated SCC with KA-like features and KA cases where the differential diagnosis is difficult from a histopathological perspective, the use of p16, p21, p53 expression and a Ki-67 proliferation index can be useful for the differential diagnosis of SCCs and KAs. PMID:27403379

  15. Comparative metabolic profiling of mce1 operon mutant vs wild-type Mycobacterium tuberculosis strains.

    PubMed

    Queiroz, Adriano; Medina-Cleghorn, Daniel; Marjanovic, Olivera; Nomura, Daniel K; Riley, Lee W

    2015-11-01

    Mycobacterium tuberculosis disrupted in a 13-gene operon (mce1) accumulates free mycolic acids (FM) in its cell wall and causes accelerated death in mice. Here, to more comprehensively analyze differences in their cell wall lipid composition, we used an untargeted metabolomics approach to compare the lipid profiles of wild-type and mce1 operon mutant strains. By liquid chromatography-mass spectrometry, we identified >400 distinct lipids significantly altered in the mce1 mutant compared to wild type. These lipids included decreased levels of saccharolipids and glycerophospholipids, and increased levels of alpha-, methoxy- and keto mycolic acids (MA), and hydroxyphthioceranic acid. The mutant showed reduced expression of mmpL8, mmpL10, stf0, pks2 and papA2 genes involved in transport and metabolism of lipids recognized to induce proinflammatory response; these lipids were found to be decreased in the mutant. In contrast, the transcripts of mmpL3, fasI, kasA, kasB, acpM and RV3451 involved in MA transport and metabolism increased; MA inhibits inflammatory response in macrophages. Since the mce1 operon is known to be regulated in intracellular M. tuberculosis, we speculate that the differences we observed in cell wall lipid metabolism and composition may affect host response to M. tuberculosis infection and determine the clinical outcome of such an infection. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  16. New Approaches to Target the Mycolic Acid Biosynthesis Pathway for the Development of Tuberculosis Therapeutics

    PubMed Central

    North, E. Jeffrey; Jackson, Mary; Lee, Richard E.

    2015-01-01

    Mycolic acids are the major lipid component of the unique mycobacterial cell wall responsible for the protection of the tuberculosis bacilli from many outside threats. Mycolic acids are synthesized in the cytoplasm and transported to the outer membrane as trehalose-containing glycolipids before being esterified to the arabinogalactan portion of the cell wall and outer membrane glycolipids. The large size of these unique fatty acids is a result of a huge metabolic investment that has been evolutionarily conserved, indicating the importance of these lipids to the mycobacterial cellular survival. There are many key enzymes involved in the mycolic acid biosynthetic pathway, including fatty acid synthesis (KasA, KasB, MabA, InhA, HadABC), mycolic acid modifying enzymes (SAM-dependent methyltransferases, aNAT), fatty acid activating and condensing enzymes (FadD32, Acc, Pks13), transporters (MmpL3) and tranferases (Antigen 85A-C) all of which are excellent potential drug targets. Not surprisingly, in recent years many new compounds have been reported to inhibit specific portions of this pathway, discovered through both phenotypic screening and target enzyme screening. In this review, we analyze the new and emerging inhibitors of this pathway discovered in the post-genomic era of tuberculosis drug discovery, several of which show great promise as selective tuberculosis therapeutics. PMID:24245756

  17. Shewanella oneidensis FabB: A β-ketoacyl-ACP Synthase That Works with C16:1-ACP.

    PubMed

    Luo, Qixia; Li, Meng; Fu, Huihui; Meng, Qiu; Gao, Haichun

    2016-01-01

    It is established that Escherichia coli β-ketoacyl-ACP synthase (KAS) I (encoded by EcfabB) is the primary, if not exclusive, factor for elongation of the cis-3-decenoyl-ACP (C10:1-ACP) but not effective with C16:1- or longer-chain-ACPs. To test the extent to which these features apply to KAS I proteins in other species, in this study, we examined the physiological role of FabB in Shewanella oneidensis, an excellent model for researching type II fatty acid synthetic (FAS) system and its regulation. We showed that the loss of either FabA (the enzyme that introduces double bond) or FabB, in the absence of DesA which desaturizes C16 and C18 to generate respective C16:1 and C18:1, leads to a UFA auxotroph. However, fatty acid profiles of membrane phospholipid of the fabA and fabB mutants are significantly different, suggesting that FabB participates in steps beyond elongation of C10:1-ACP. Further analyses demonstrated that S. oneidensis FabB differs from EcFabB in that (i) it is not the only enzyme capable of catalyzing elongation of the cis-3-decenoyl-ACP produced by FabA, (ii) it plays a critical role in elongation of C16:1- and longer-chain-ACPs, and (iii) its overproduction is detrimental.

  18. Investigation of co-combustion characteristics of sewage sludge and coffee grounds mixtures using thermogravimetric analysis coupled to artificial neural networks modeling.

    PubMed

    Chen, Jiacong; Liu, Jingyong; He, Yao; Huang, Limao; Sun, Shuiyu; Sun, Jian; Chang, KenLin; Kuo, Jiahong; Huang, Shaosong; Ning, Xunan

    2017-02-01

    Artificial neural network (ANN) modeling was applied to thermal data obtained by non-isothermal thermogravimetric analysis (TGA) from room temperature to 1000°C at three different heating rates in air to predict the TG curves of sewage sludge (SS) and coffee grounds (CG) mixtures. A good agreement between experimental and predicted data verified the accuracy of the ANN approach. The results of co-combustion showed that there were interactions between SS and CG, and the impacts were mostly positive. With the addition of CG, the mass loss rate and the reactivity of SS were increased while charring was reduced. Measured activation energies (Ea) determined by the Kissinger-Akahira-Sunose (KAS) and Ozawa-Flynn-Wall (OFW) methods deviated by <5%. The average value of Ea (166.8kJ/mol by KAS and 168.8kJ/mol by OFW, respectively) was the lowest when the fraction of CG in the mixture was 40%. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Is it safe to place a tibial intramedullary nail through a traumatic knee arthrotomy?

    PubMed

    Bauer, Jennifer M; Bible, Jesse E; Mir, Hassan R

    2014-03-01

    We conducted a study to compare postoperative infection and nonunion rates in tibial intramedullary nails (IMNs) placed through either uninjured knees or traumatic knee arthrotomies (KAs). We reviewed all adult tibial diaphyseal fractures (n = 1378) treated with an IMN between 1998 and 2010. Fourteen of these nails were placed through a traumatic KA. Each patient in the study group was assigned 4 separate matched controls for comparison. Controls were matched on age, sex, diabetes, smoking, and fracture classification (closed or open with Gustilo-Anderson). There were no postoperative infections (knee or fracture site) in the traumatic KA group and 2 (3.5%) in the control group (P = .473). One nonunion (7.1%) was noted in the traumatic KA group, and 9 (16%) were noted in the control group (P = .6694). To our knowledge, this is the first study to report outcomes of placing tibial IMNs through traumatic KAs. In our sample, the practice presented no increased risk either for infection (at the knee or the fracture site) or for nonunion with appropriate surgical debridement.

  20. Characteristics and kinetics study of simultaneous pyrolysis of microalgae Chlorella vulgaris, wood and polypropylene through TGA.

    PubMed

    Azizi, Kolsoom; Keshavarz Moraveji, Mostafa; Abedini Najafabadi, Hamed

    2017-11-01

    Thermal decomposition behavior and kinetics of microalgae Chlorella vulgaris, wood and polypropylene were investigated using thermogravimetric analysis (TGA). Experiments were carried out at heating rates of 10, 20 and 40°C/min from ambient temperature to 600°C. The results show that pyrolysis process of C. vulgaris and wood can be divided into three stages while pyrolysis of polypropylene occurs almost totally in one step. It is shown that wood can delay the pyrolysis of microalgae while microalgae can accelerate the pyrolysis of wood. The existence of polymer during the pyrolysis of microalgae or wood will lead to two divided groups of peaks in DTG curve of mixtures. The results showed that interaction is inhibitive rather than synergistic during the decomposition process of materials. Kinetics of process is studied by the Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO). The average E values obtained from FWO and KAS methods were 131.228 and 142.678kJ/mol, respectively. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Kinetics of petroleum coke/biomass blends during co-gasification

    NASA Astrophysics Data System (ADS)

    Zhang, Jian-liang; Guo, Jian; Wang, Guang-wei; Xu, Tao; Chai, Yi-fan; Zheng, Chang-le; Xu, Run-sheng

    2016-09-01

    The co-gasification behavior and synergistic effect of petroleum coke, biomass, and their blends were studied by thermogravimetric analysis under CO2 atmosphere at different heating rates. The isoconversional method was used to calculate the activation energy. The results showed that the gasification process occurred in two stages: pyrolysis and char gasification. A synergistic effect was observed in the char gasification stage. This effect was caused by alkali and alkaline earth metals in the biomass ash. Kinetics analysis showed that the activation energy in the pyrolysis stage was less than that in the char gasification stage. In the char gasification stage, the activation energy was 129.1-177.8 kJ/mol for petroleum coke, whereas it was 120.3-150.5 kJ/mol for biomass. We also observed that the activation energy calculated by the Flynn-Wall-Ozawa (FWO) method were larger than those calculated by the Kissinger-Akahira-Sunosen (KAS) method. When the conversion was 1.0, the activation energy was 106.2 kJ/mol when calculated by the KAS method, whereas it was 120.3 kJ/mol when calculated by the FWO method.

  2. Expression of fatty acid synthesis genes and fatty acid accumulation in haematococcus pluvialis under different stressors

    PubMed Central

    2012-01-01

    Background Biofuel has been the focus of intensive global research over the past few years. The development of 4th generation biofuel production (algae-to-biofuels) based on metabolic engineering of algae is still in its infancy, one of the main barriers is our lacking of understanding of microalgal growth, metabolism and biofuel production. Although fatty acid (FA) biosynthesis pathway genes have been all cloned and biosynthesis pathway was built up in some higher plants, the molecular mechanism for its regulation in microalgae is far away from elucidation. Results We cloned main key genes for FA biosynthesis in Haematococcus pluvialis, a green microalga as a potential biodiesel feedstock, and investigated the correlations between their expression alternation and FA composition and content detected by GC-MS under different stress treatments, such as nitrogen depletion, salinity, high or low temperature. Our results showed that high temperature, high salinity, and nitrogen depletion treatments played significant roles in promoting microalgal FA synthesis, while FA qualities were not changed much. Correlation analysis showed that acyl carrier protein (ACP), 3-ketoacyl-ACP-synthase (KAS), and acyl-ACP thioesterase (FATA) gene expression had significant correlations with monounsaturated FA (MUFA) synthesis and polyunsaturated FA (PUFA) synthesis. Conclusions We proposed that ACP, KAS, and FATA in H. pluvialis may play an important role in FA synthesis and may be rate limiting genes, which probably could be modified for the further study of metabolic engineering to improve microalgal biofuel quality and production. PMID:22448811

  3. Expression of fatty acid synthesis genes and fatty acid accumulation in haematococcus pluvialis under different stressors.

    PubMed

    Lei, Anping; Chen, Huan; Shen, Guoming; Hu, Zhangli; Chen, Lei; Wang, Jiangxin

    2012-03-26

    Biofuel has been the focus of intensive global research over the past few years. The development of 4th generation biofuel production (algae-to-biofuels) based on metabolic engineering of algae is still in its infancy, one of the main barriers is our lacking of understanding of microalgal growth, metabolism and biofuel production. Although fatty acid (FA) biosynthesis pathway genes have been all cloned and biosynthesis pathway was built up in some higher plants, the molecular mechanism for its regulation in microalgae is far away from elucidation. We cloned main key genes for FA biosynthesis in Haematococcus pluvialis, a green microalga as a potential biodiesel feedstock, and investigated the correlations between their expression alternation and FA composition and content detected by GC-MS under different stress treatments, such as nitrogen depletion, salinity, high or low temperature. Our results showed that high temperature, high salinity, and nitrogen depletion treatments played significant roles in promoting microalgal FA synthesis, while FA qualities were not changed much. Correlation analysis showed that acyl carrier protein (ACP), 3-ketoacyl-ACP-synthase (KAS), and acyl-ACP thioesterase (FATA) gene expression had significant correlations with monounsaturated FA (MUFA) synthesis and polyunsaturated FA (PUFA) synthesis. We proposed that ACP, KAS, and FATA in H. pluvialis may play an important role in FA synthesis and may be rate limiting genes, which probably could be modified for the further study of metabolic engineering to improve microalgal biofuel quality and production.

  4. Identification of the Submergence Tolerance QTL Come Quick Drowning1 (CQD1) in Arabidopsis thaliana.

    PubMed

    Akman, Melis; Kleine, Rogier; van Tienderen, Peter H; Schranz, M Eric

    2017-02-16

    Global climate change is predicted to increase water precipitation fluctuations and lead to localized prolonged floods in agricultural fields and natural plant communities. Thus, understanding the genetic basis of submergence tolerance is crucial in order to improve plant survival under these conditions. In this study, we performed a quantitative trait locus (QTL) analysis in Arabidopsis to identify novel candidate genes for increased submergence tolerance by using Kas-1 and Col (gl1) parental accessions and their derived recombinant inbred lines (RILs). We measured survival after submergence in dark for a 13-day period and used median lethal time, LT50 values for the QTL analysis. A major QTL, the Come Quick, Drowning (CQD1) locus, was detected in 2 independent experiments on the lower arm of chromosome 5 involved in higher submergence tolerance in the parental accession Kas-1. For fine-mapping, we then constructed near isogenic lines (NILs) by backcrossing the CQD1 QTL region. We also analyzed QTL regions related to size, leaf number, flowering, or survival in darkness and none of the QTL related to these traits overlapped with CQD1. The submergence tolerance QTL, CQD1, region detected in this study includes genes that have potential to be novel candidates effecting submergence tolerance such as trehalose-6-phosphate phosphatase and respiratory burst oxidase protein D. Gene expression and functional analysis for these genes under submergence would reveal the significance of these novel candidates and provide new perspectives for understanding genetic basis of submergence tolerance.

  5. Taphonomy and palaeoecology of Late Triassic (Carnian) ammonoid concentrations from the Taurus Mountains, Turkey.

    PubMed

    Mayrhofer, Susanne; Lukeneder, Alexander; Krystyn, Leopold

    2017-01-01

    The deposits of the Carnian Kasımlar Formation within the Taurus Platform Units of south-western Turkey represent an important archive of a Late Triassic ecosystem. New palaeontological information was obtained by analysing the Kasimlarceltites mass occurrence, located within the Kasımlar Formation and named after the Lower Carnian (Julian) ammonoid genus Kasimlarceltites. This is the dominant taxon (> 94%) within the mass occurrence: nearly 775 million ammonoids and 50 million gastropods were extrapolated for the whole extension (at least 5 km(2)) of the Kasimlarceltites beds. This calculation is one of the main findings within this study, as it is the first time that such a fossil mass occurrence was quantified. Additionally, orientation measurements of the planispiral ammonoids and the helical gastropods enabled reconstructing the history of the mass occurrence and interpreting the underlying transport mechanisms. Further taphonomic aspects (e.g. biofabric, preservation, bioerosion or genetic classification) as well as comparisons with samples of the same acme zone from different localities near Aşağiyaylabel (AS IV, KA I-II) point to a two-phased genetic history. Accordingly, local mass mortality within the Kasimlarceltites fauna due to oxygen fluctuations or methane degassing may have initially led to a primary accumulation. These deposits were then reworked and redeposited basinward by gravity flows to create the present-day secondary allochthonous concentrations.

  6. Kinetic modelling of RDF pyrolysis: Model-fitting and model-free approaches.

    PubMed

    Çepelioğullar, Özge; Haykırı-Açma, Hanzade; Yaman, Serdar

    2016-02-01

    In this study, refuse derived fuel (RDF) was selected as solid fuel and it was pyrolyzed in a thermal analyzer from room temperature to 900°C at heating rates of 5, 10, 20, and 50°C/min in N2 atmosphere. The obtained thermal data was used to calculate the kinetic parameters using Coats-Redfern, Friedman, Flylnn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) methods. As a result of Coats-Redfern model, decomposition process was assumed to be four independent reactions with different reaction orders. On the other hand, model free methods demonstrated that activation energy trend had similarities for the reaction progresses of 0.1, 0.2-0.7 and 0.8-0.9. The average activation energies were found between 73-161kJ/mol and it is possible to say that FWO and KAS models produced closer results to the average activation energies compared to Friedman model. Experimental studies showed that RDF may be a sustainable and promising feedstock for alternative processes in terms of waste management strategies.

  7. An operational model of pharmacological agonism: the effect of E/[A] curve shape on agonist dissociation constant estimation.

    PubMed Central

    Black, J. W.; Leff, P.; Shankley, N. P.; Wood, J.

    1985-01-01

    An operational model of pharmacological agonism has been analysed to predict the behaviour of rectangular hyperbolic and non-hyperbolic agonist-concentration effect, E/[A], curves with variation in receptor concentration, [Ro]. Irreversible antagonism is predicted to cause E/[A] curve gradient changes in non-hyperbolic cases but not in hyperbolic cases; in both cases estimation of agonist dissociation constants (KAS) is theoretically valid. 5-Hydroxytryptamine (5-HT) produced "steep' E/[A] curves in contracting the rabbit isolated aorta preparation. Irreversible antagonism by phenoxybenzamine (Pbz) produced a flattened E/[A] curve, consistent with theoretical predictions. Fitting 5-HT E/[A] curves in the presence and absence of Pbz to the model provided an estimate of KA for 5-HT which was not significantly different from the estimate obtained using Furchgott's null method. The operational model of agonism appears to account qualitatively and quantitatively for the effects of [Ro] changes on hyperbolic and non-hyperbolic E/[A] curves. Under conditions where irreversible antagonism may be used to estimate KAS, fitting the operational model directly to E/[A] data represents a valid, economical and analytically simple alternative to the conventional null method. PMID:3978322

  8. Evaluation of the Uniform Field Distortions Produced by a Toroidal Dielectric Body / Novērtējums Viendabīga Elektriskā Lauka Izkropļojumiem, Kurus Rada Toroīda Formas Dielektrisks Ķermenis

    NASA Astrophysics Data System (ADS)

    Krasnitsky, Y. A.; Popov, A. E.; Kalnacs, A.

    2015-08-01

    Distortions of the structure of a uniform electric field when a dielectric body with a toroidal shape is placed in it are considered in the quasi-static approximation. The rate of distortion is proposed to estimate through the effective permittivity of toroid determined by solving the corresponding boundary value problem. Some numerical estimates obtained using specially developed software in the language of Matlab are given. Darbā apskatīts kvazi-statisks tuvinājums viendabīga elektriskā lauka izkropļojumiem gadījumos, kad tajā tiek ievietots dielektrisks toroīda formas ķermenis. Izkropļojumu apmēru tiek piedāvāts novērtēt ar toroīda efektīvo caurlaidību, kas tiek noteikta, atrisinot atbilstošo robežvērtību uzdevumu. Tiek doti skaitliski novērtējumi, kas iegūti, lietojot speciāli valodā Matlab izstrādātu programmatūru.

  9. Organic facies characteristics of the Triassic Kasimlar Formation, Anamas-Akseki Platform, western Taurides, Turkey

    NASA Astrophysics Data System (ADS)

    Hokerek, Selin; Unal, Neslihan; Altunsoy, Mehmet; Ozcelik, Orhan; Kuscu, Mustafa

    2014-05-01

    In the Anamas-Akseki platform (SW Turkey), the Triassic Kasımlar Formation consists of bituminous shale and bedded reefal limestones. Detailed data from thick Triassic sediments (Kasımlar Formation) made it possible to construct an organic facies framework using different zonations. Organic matter is composed predominantly of woody material, with a minor contribution of planty and amorphous material. Kerogen in the deposits is type III, as indicated by organic petrographic observations and Rock-Eval data. Total organic carbon (TOC) values are generally between 0.02 and 0.96 %, but reach 3.78 % in the formation. Tmax values vary between 284 and 454 °C, confirming the increase in maturation trends indicated by vitrinite reflectance data. Organic facies type D was identified in the investigated units. Organic facies D is related to shale and carbonate lithofacies. This facies is characterized by average values of HI around 19 (equivalent to type III kerogene), TOC around 0.51 %, and an average of S2 of 0.04 mg HC/g of rock. Organic facies D is nongenerative; the organic matter is highly oxidized, decomposed and reworked. Keywords: Western Taurus Belt; Akseki Anamas Platform; organic facies

  10. Cloning, expression, crystallization and preliminary X-ray crystallographic analysis of beta-ketoacyl-ACP synthase III (FabH) from Xanthomonas oryzae pv. oryzae.

    PubMed

    Huynh, Kim Hung; Natarajan, Sampath; Song, Na Hyun; Ngo, Phuong Thuy Ho; Ahn, Yeh Jin; Kim, Jeong Gu; Lee, Byoung Moo; Eo, Yang Dam; Kang, Lin Woo

    2009-05-01

    The bacterial beta-ketoacyl-ACP synthase III (KASIII) encoded by the gene fabH (Xoo4209) from Xanthomonas oryzae pv. oryzae, a plant pathogen, is an important enzyme in the elongation steps of fatty-acid biosynthesis. It is expected to be one of the enzymes responsible for bacterial blight (BB), a serious disease that results in huge production losses of rice. As it represents an important target for the development of new antibacterial drugs against BB, determination of the crystal structure of the KAS III enzyme is essential in order to understand its reaction mechanism. In order to analyze the structure and function of KAS III, the fabH (Xoo4209) gene was cloned and the enzyme was expressed and purified. The KASIII crystal diffracted to 2.05 A resolution and belonged to the orthorhombic space group P2(1)2(1)2, with unit-cell parameters a = 69.8, b = 79.5, c = 62.3 A. The unit-cell volume of the crystal is compatible with the presence of a single monomer in the asymmetric unit, with a corresponding Matthews coefficient V(M) of 2.27 A(3) Da(-1) and a solvent content of 45.8%.

  11. Should epitope-based HLA compatibility be used in the kidney allocation system?

    PubMed

    Duquesnoy, Rene J

    2017-01-01

    The new kidney allocation system (KAS) still applies donor-recipient HLA compatibility mostly at the antigen level and although some four-digit alleles have been included. This system is used to record unacceptable mismatches for sensitized transplant candidates with serum HLA antibodies. Since the reactivities of such antibodies are specifically associated with epitopes rather than HLA antigens, a more scientifically accurate assessment of mismatch acceptability could be based on epitopes. HLA class I and class II epitope specificity analyses can now be readily performed with serum antibody assays with single allele panels. This report describes an epitope-based HLA compatibility system for KAS and involves recipient and donor HLA typing at the four-digit allele level. It focuses on sensitized patients who have serum antibodies specific for HLA epitopes that can be entered as unacceptable mismatches in the transplant candidate database. Newly developed software programs could readily identify compatible HLA types. Copyright © 2016 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.

  12. Root cause analysis of limitations of virtual crossmatch for kidney allocation to highly-sensitized patients.

    PubMed

    Jani, Vivek; Ingulli, Elizabeth; Mekeel, Kristen; Morris, Gerald P

    2017-02-01

    Efficient allocation of deceased donor organs depends upon effective prediction of immunologic compatibility based on donor HLA genotype and recipient alloantibody profile, referred to as virtual crossmatching (VCXM). VCXM has demonstrated utility in predicting compatibility, though there is reduced efficacy for patients highly sensitized against allogeneic HLA antigens. The recently revised deceased donor kidney allocation system (KAS) has increased transplantation for this group, but with an increased burden for histocompatibility testing and organ sharing. Given the limitations of VCXM, we hypothesized that increased organ offers for highly-sensitized patients could result in a concomitant increase in offers rejected due to unexpectedly positive crossmatch. Review of 645 crossmatches performed for deceased donor kidney transplantation at our center did not reveal a significant increase in positive crossmatches following KAS implementation. Positive crossmatches not predicted by VCXM were concentrated among highly-sensitized patients. Root cause analysis of VCXM failures identified technical limitations of anti-HLA antibody testing as the most significant contributor to VCXM error. Contributions of technical limitations including additive/synergistic antibody effects, prozone phenomenon, and antigens not represented in standard testing panels, were evaluated by retrospective testing. These data provide insight into the limitations of VCXM, particularly those affecting allocation of kidneys to highly-sensitized patients.

  13. Kinetic analyses and pyrolytic behavior of Para grass (Urochloa mutica) for its bioenergy potential.

    PubMed

    Ahmad, Muhammad Sajjad; Mehmood, Muhammad Aamer; Al Ayed, Omar S; Ye, Guangbin; Luo, Huibo; Ibrahim, Muhammad; Rashid, Umer; Arbi Nehdi, Imededdine; Qadir, Ghulam

    2017-01-01

    The biomass of Urochloa mutica was subjected to thermal degradation analyses to understand its pyrolytic behavior for bioenergy production. Thermal degradation experiments were performed at three different heating rates, 10, 30 and 50°Cmin(-1) using simultaneous thermogravimetric-differential scanning calorimetric analyzer, under an inert environment. The kinetic analyses were performed using isoconversional models of Kissenger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO). The high heating value was calculated as 15.04MJmol(-1). The activation energy (E) values were shown to be ranging from 103 through 233 kJmol(-1). Pre-exponential factors (A) indicated the reaction to follow first order kinetics. Gibbs free energy (ΔG) was measured to be ranging from 169 to 173kJmol(-1) and 168 to 172kJmol(-1), calculated by KAS and FWO methods, respectively. We have shown that Para grass biomass has considerable bioenergy potential comparable to established bioenergy crops such as switchgrass and miscanthus.

  14. Acidity constants and redox potentials of uranyl ions in hydrothermal solutions.

    PubMed

    Liu, Xiandong; Cheng, Jun; He, Mengjia; Lu, Xiancai; Wang, Rucheng

    2016-09-21

    We report a first principles molecular dynamics (FPMD) study of the structures, acidity constants (pKa) and redox potentials (E(0)) of uranyl (UO2(2+)) from ambient conditions to 573 K. It is found that UO2(2+) keeps five coordination up to 573 K whereas UO2(+) transforms from 5 to 4-coordinate as temperature increases to 573 K. The FPMD-based vertical energy gap method is used to derive pKas and E(0)s. The method is validated by comparing with available experimental data (for E(0) under the ambient conditions and for pKas from ambient conditions to 367 K), with an uncertainty of 1-2 pKa units and 0.2 V for pKa and E(0). The encouraging results demonstrate that the method may be used to predict the pH-Eh diagrams of f-block elements under the conditions of hydrothermal solutions. The results show that the acidity constants of uranyl decrease with temperature and are lower than 3.0 when the temperature is above 473 K, indicating that hydrolytic forms are dominant for U(vi) in the near neutral pH range. The reduction potential increases with temperature, indicating that the reduced state is more significant at higher temperatures.

  15. Identification of gene-specific polymorphisms and association with capsaicin pathway metabolites in Capsicum annuum L. collections.

    PubMed

    Reddy, Umesh K; Almeida, Aldo; Abburi, Venkata L; Alaparthi, Suresh Babu; Unselt, Desiree; Hankins, Gerald; Park, Minkyu; Choi, Doil; Nimmakayala, Padma

    2014-01-01

    Pepper (Capsicum annuum L.) is an economically important crop with added nutritional value. Production of capsaicin is an important quantitative trait with high environmental variance, so the development of markers regulating capsaicinoid accumulation is important for pepper breeding programs. In this study, we performed association mapping at the gene level to identify single nucleotide polymorphisms (SNPs) associated with capsaicin pathway metabolites in a diverse Capsicum annuum collection during two seasons. The genes Pun1, CCR, KAS and HCT were sequenced and matched with the whole-genome sequence draft of pepper to identify SNP locations and for further characterization. The identified SNPs for each gene underwent candidate gene association mapping. Association mapping results revealed Pun1 as a key regulator of major metabolites in the capsaicin pathway mainly affecting capsaicinoids and precursors for acyl moieties of capsaicinoids. Six different SNPs in the promoter sequence of Pun1 were found associated with capsaicin in plants from both seasons. Our results support that CCR is an important control point for the flux of p-coumaric acid to specific biosynthesis pathways. KAS was found to regulate the major precursors for acyl moieties of capsaicinoids and may play a key role in capsaicinoid production. Candidate gene association mapping of Pun1 suggested that the accumulation of capsaicinoids depends on the expression of Pun1, as revealed by the most important associated SNPs found in the promoter region of Pun1.

  16. Small Hydropower in Latvia and Intellectualization of its Operating Systems / Par Mazo HIDROENERĢĒTIKU LATVIJĀ un TĀS Staciju VADĪBAS SISTĒMAS INTELEKTUALIZĀCIJU

    NASA Astrophysics Data System (ADS)

    Mahnitko, A.; Gerhards, J.; Linkevics, O.; Varfolomejeva, R.; Umbrasko, I.

    2013-12-01

    The authors estimate the potential for power generation from water resources of small and medium-sized rivers, which are abundant in Latvia. They propose the algorithm for optimal operation of a small-scale hydropower plant (SHPP) at the chosen optimality criterion in view of the plant's participation in the market. The choice of SHPP optimization algorithm is made based on two mathematical programming methods - dynamic and generalized reduced gradient ones. Approbation of the algorithm is illustrated by an example of optimized SHPP operation. Darbā analizētas tradicionālo un pieejamo vietējo atjaunojamo energoresursu - mazo un vidējo upju hidroresursa izmantošanas iespējas Latvijas enerģētikā. Tiek sniegts faktiskais materiāls šajā jautājumā, kas iegūts, balstoties uz oficiālos avotos publicētiem citu autoru iepriekš veiktajiem pētījumiem. Tiek atzīmēts, ka teritoriju, kas atrodas mazo upju tuvumā un nav ietvertas centralizētās elektroapgādes sistēmā, saimnieciskā apgūšana rada apstākļus patērētāju stimulēšanai izmantot autonomus vietējos energoresursus, ieskaitot hidroenerģiju, izmantojošas mazas jaudas energoiekārtas. Atjaunojamās enerģijas tehnoloģiju un iekārtu pastāvīga attīstība un pilnveidošanās veicinās mazo upju plūsmas izmantošanas elektroenerģijas ražošanas efektivitātes paaugstināšanos. Mūsdienu enerģētikas attīstības koncepcija, kas balstīta uz viedo tīklu (smart grids) izveidi, ļauj paaugstināt mazās hidroenerģētikas darbības efektivitāti, integrējot to elektroenerģētiskajā sistēmā. Mazo hidroelektrostaciju (MHES) darbības vadības sistēmas intelektualizācijas pamatā jābūt kompleksam algoritmam un programmām, kas ļauj tiešsaistes (online) režīmā nodrošināt izdevīgu MHES darbības grafiku (režīmu) maksimālā ienākuma gūšanai, balstoties uz zināmu elektroenerģijas cenas prognozi attiecīgajam laika periodam (diennaktij). MHES darbības optimiz

  17. Toward Quantitatively Accurate Calculation of the Redox-Associated Acid–Base and Ligand Binding Equilibria of Aquacobalamin

    DOE PAGES

    Johnston, Ryne C.; Zhou, Jing; Smith, Jeremy C.; ...

    2016-07-08

    In redox processes in complex transition metal-containing species are often intimately associated with changes in ligand protonation states and metal coordination number. Moreover, a major challenge is therefore to develop consistent computational approaches for computing pH-dependent redox and ligand dissociation properties of organometallic species. Reduction of the Co center in the vitamin B12 derivative aquacobalamin can be accompanied by ligand dissociation, protonation, or both, making these properties difficult to compute accurately. We examine this challenge here by using density functional theory and continuum solvation to compute Co ligand binding equilibrium constants (Kon/off), pKas and reduction potentials for models of aquacobalaminmore » in aqueous solution. We consider two models for cobalamin ligand coordination: the first follows the hexa, penta, tetra coordination scheme for CoIII, CoII, and CoI species, respectively, and the second model features saturation of each vacant axial coordination site on CoII and CoI species with a single, explicit water molecule to maintain six directly interacting ligands or water molecules in each oxidation state. Comparing these two coordination schemes in combination with five dispersion-corrected density functionals, we find that the accuracy of the computed properties is largely independent of the scheme used, but including only a continuum representation of the solvent yields marginally better results than saturating the first solvation shell around Co throughout. PBE performs best, displaying balanced accuracy and superior performance overall, with RMS errors of 80 mV for seven reduction potentials, 2.0 log units for five pKas and 2.3 log units for two log Kon/off values for the aquacobalamin system. Furthermore, we find that the BP86 functional commonly used in corrinoid studies suffers from erratic behavior and inaccurate descriptions of Co axial ligand binding, leading to substantial errors in predicted

  18. Effect of submerged, freshwater aquatic macrophytes and littoral sediments on pan evaporation in the Lake Balaton region, Hungary

    NASA Astrophysics Data System (ADS)

    Anda, A.; Simon, B.; Soos, G.; Teixeira da Silva, J. A.; Kucserka, T.

    2016-11-01

    The evaporation (Ep) of a US Class A pan (C) with submerged, freshwater aquatic macrophytes (Potamogeton perfoliatus, Myriophyllum spicatum and Najas marina), hereafter macrophytes (Ps) and a sediment-covered bottom (S) was measured in Hungary during 2014-2015 using reference E of Shuttleworth (Eo) and Penman-Monteith crop reference evapotranspiration (crop ETo). There were two main climatic controls affecting variation in E: direct (air and water temperature) and indirect (wind-mediated change affecting the penetration of sunlight; precipitation inflow, impacting plant emergence). Lower seasonal mean Ep rates of 2.75 ± 0.89, 2.83 ± 0.91 and 3.06 ± 1.14 mm day-1 were observed in C, S and Ps, respectively, during the wet 2014. In the 2015 season, higher overall daily mean Ep rates for C, S and Ps were 3.76 ± 1.3, 4.19 ± 1.34 and 4.65 ± 1.52 mm day-1, respectively. A comparison of US Class A pan Ep containing macrophytes/sediments with that of a standard US Class A pan showed that pan coefficients (Kap and Kas) might allow for more accurate on-site lake E estimates. In 2014, seasonal mean Kas and Kap were 1.04 ± 0.14 and 1.09 ± 0.18, respectively. Slightly higher Ka values were observed during the warm and dry 2015 (Kas: 1.15 ± 0.22; Kap: 1.26 ± 0.23). A Ka value greater than 1 indicates that the Ep of a US Class A pan containing macrophytes and sediment is always higher than that of C. The calculated Eo overestimated measured Ep of Ps during the course of this study. During the warm-dry growing season, crop ETo was closest to Ep of Ps. Empirical coefficients can be useful for estimating E of lakes with submerged macrophytes more precisely. The accuracy of the estimate of Keszthely Bay's E improved by 9.85% when Ka was determined on site.

  19. Digitally Controlled 4-Phase Bi-Directional Interleaved Dc-Dc Converter with Coupled Inductors / Digitāli Vadāms 4 Fāžu Divvirziena Līdzstrāvas Pārveidotājs Ar Saistītajām Droselēm

    NASA Astrophysics Data System (ADS)

    Kroics, K.; Sirmelis, U.; Grigans, L.

    2015-08-01

    The main advantages of multiphase interleaved DC-DC converters over single-phase converters are reduced current stress and reduced output current ripple. Nevertheless, inductor current ripple cannot be reduced only by an interleaving method. The integrated magnetic structure can be used to solve this problem. In this paper, the application of 2-phase coupled inductor designed in a convenient way by using commercially manufactured coil formers and ferrite cores is analysed to develop a 4-phase interleaved DC-DC converter. The steady state phase and output current ripple in a boost mode of the interleaved bidirectional DC-DC converter with integrated magnetics are analysed. The prototype of the converter has been built. The experimental results of the current ripple are presented in the paper. Šajā rakstā piedāvāta magnētiski saistīta drosele, kas izveidota, izmantojot plaša patēriņa ferrīta serdi un tinuma formētāju. Izmantojot šādas droseles, var tikt izveidots vairākfāžu pārveidotājs ar mazām izejas un iejas strāvas pulsācijām, kā arī samazinātām strāvas pulsācijām droselē. Rakstā sīkāk apskatīts līdzstrāvas pārveidotājs, kas sastāv no četrām fāzēm. Šim gadījumam izvestas teorētiskās formulas strāvas pulsāciju aprēķinam, kā arī rakstā parādīti eksperimentālie rezultāti, kas iegūti, testējot prototipu. Teorētiskie rezultāti sakrīt ar eksperimentālajiem

  20. Toward Quantitatively Accurate Calculation of the Redox-Associated Acid-Base and Ligand Binding Equilibria of Aquacobalamin.

    PubMed

    Johnston, Ryne C; Zhou, Jing; Smith, Jeremy C; Parks, Jerry M

    2016-08-04

    Redox processes in complex transition metal-containing species are often intimately associated with changes in ligand protonation states and metal coordination number. A major challenge is therefore to develop consistent computational approaches for computing pH-dependent redox and ligand dissociation properties of organometallic species. Reduction of the Co center in the vitamin B12 derivative aquacobalamin can be accompanied by ligand dissociation, protonation, or both, making these properties difficult to compute accurately. We examine this challenge here by using density functional theory and continuum solvation to compute Co-ligand binding equilibrium constants (Kon/off), pKas, and reduction potentials for models of aquacobalamin in aqueous solution. We consider two models for cobalamin ligand coordination: the first follows the hexa, penta, tetra coordination scheme for Co(III), Co(II), and Co(I) species, respectively, and the second model features saturation of each vacant axial coordination site on Co(II) and Co(I) species with a single, explicit water molecule to maintain six directly interacting ligands or water molecules in each oxidation state. Comparing these two coordination schemes in combination with five dispersion-corrected density functionals, we find that the accuracy of the computed properties is largely independent of the scheme used, but including only a continuum representation of the solvent yields marginally better results than saturating the first solvation shell around Co throughout. PBE performs best, displaying balanced accuracy and superior performance overall, with RMS errors of 80 mV for seven reduction potentials, 2.0 log units for five pKas and 2.3 log units for two log Kon/off values for the aquacobalamin system. Furthermore, we find that the BP86 functional commonly used in corrinoid studies suffers from erratic behavior and inaccurate descriptions of Co-axial ligand binding, leading to substantial errors in predicted pKas and

  1. Allocating Deceased Donor Kidneys to Candidates with High Panel–Reactive Antibodies

    PubMed Central

    Gebel, Howard M.; Kasiske, Bertram L.; Gustafson, Sally K.; Pyke, Joshua; Shteyn, Eugene; Bray, Robert A.; Snyder, Jon J.; Friedewald, John J.; Segev, Dorry L.

    2016-01-01

    Background and objectives In December of 2014, the Organ Procurement and Transplant Network implemented a new Kidney Allocation System (KAS) for deceased donor transplant, with increased priority for highly sensitized candidates (calculated panel–reactive antibody [cPRA] >99%). We used a modified version of the new KAS to address issues of access and equity for these candidates. Design, setting, participants, & measurements In a simulation, 10,988 deceased donor kidneys transplanted into waitlisted recipients in 2010 were instead allocated to candidates with cPRA≥80% (n=18,004). Each candidate’s unacceptable donor HLA antigens had been entered into the allocation system by the transplant center. In simulated match runs, kidneys were allocated sequentially to adult ABO identical or permissible candidates with cPRA 100%, 99%, 98%, etc. to 80%. Allocations were restricted to donor/recipient pairs with negative virtual crossmatches. Results The simulation indicated that 2111 of 10,988 kidneys (19.2%) would have been allocated to patients with cPRA 100% versus 74 of 10,988 (0.7%) that were actually transplanted. Of cPRA 100% candidates, 74% were predicted to be compatible with an average of six deceased donors; the remaining 26% seemed to be incompatible with every deceased donor organ that entered the system. Of kidneys actually allocated to cPRA 100% candidates in 2010, 66% (49 of 74) were six–antigen HLA matched/zero–antigen mismatched (HLA-A, -B, and -DR) with their recipients versus only 11% (237 of 2111) in the simulation. The simulation predicted that 10,356 of 14,433 (72%) candidates with cPRA 90%–100% could be allocated an organ compared with 7.3% who actually underwent transplant. Conclusions Data in this simulation are consistent with early results of the new KAS; specifically, nearly 20% of deceased donor kidneys were (virtually) compatible with cPRA 100% candidates. Although most of these candidates were predicted to be compatible with multiple

  2. Enhanced metabolic effect of erythropoietin and keto acids in CRF patients on low-protein diet: Czech multicenter study.

    PubMed

    Teplan, Vladimír; Schück, Otto; Knotek, Antonín; Hajný, Jan; Horácková, Miroslava; Kvapil, Milan

    2003-03-01

    Our study is designed to establish whether supplementation with erythropoietin (EPO) exerts additional beneficial metabolic effects in patients with chronic renal failure (CRF) treated with keto acids (KAs) on a low-protein diet (LPD). A long-term, prospective, randomized study was designed to use three therapeutic protocols: (A) EPO plus KAs plus LPD (group I), (B) EPO plus LPD (group II), and (C) LPD (group III). One hundred eighty-six randomly selected patients (90 men, 96 women; age, 22 to 78 years) with a creatinine clearance of 22 to 36 mL/min were monitored at the beginning and at every 6 months for 3 years. During the study period, glomerular filtration rate measured as inulin clearance decreased slightly (from 26.2 +/- 3.4 to 23.4 +/- 4.1 mL/min in group I), 27.4 +/- 4.8 to 20.2 +/- 4.4 mL/min in group II, and 26.8 +/- 3.6 to 17.4 +/- 4.1 mL/min in group III; P < 0.01). Serum urea levels also declined (P < 0.01), more pronouncedly in group I (P < 0.025). In group I, there was a significant increase in levels of leucine (P < 0.01) and albumin (P < 0.01) and a decrease in proteinuria (P < 0.01). Analysis of the lipid spectrum showed a mild, yet significant, decrease in total cholesterol and low-density lipoprotein cholesterol levels (P < 0.025), more pronounced in group I. In group I, there was a decrease in plasma triglyceride levels (from 362.85 +/- 115.05 mg/dL [4.1 +/- 1.3 mmol/L] to values as low as 203.55 +/- 70.80 mg/dL [2.3 +/- 0.8 mmol/L]; P < 0.01), whereas high-density lipoprotein cholesterol levels increased (from 34.75 +/- 7.72 mg/dL [0.9 +/- 0.2 mmol/L] to 46.33 +/- 7.72 mg/dL [1.2 +/- 0.2 mmol/L]; P < 0.025). Mean arterial blood pressure was stable. EPO supplementation in patients with CRF administered KAs potentiates the beneficial effects on metabolism of proteins, amino acids, and lipids. Long-term coadministration of EPO, KA, and LPD was associated with a delay in progression of renal failure and reduction in proteinuria.

  3. Allocating Deceased Donor Kidneys to Candidates with High Panel-Reactive Antibodies.

    PubMed

    Gebel, Howard M; Kasiske, Bertram L; Gustafson, Sally K; Pyke, Joshua; Shteyn, Eugene; Israni, Ajay K; Bray, Robert A; Snyder, Jon J; Friedewald, John J; Segev, Dorry L

    2016-03-07

    In December of 2014, the Organ Procurement and Transplant Network implemented a new Kidney Allocation System (KAS) for deceased donor transplant, with increased priority for highly sensitized candidates (calculated panel-reactive antibody [cPRA] >99%). We used a modified version of the new KAS to address issues of access and equity for these candidates. In a simulation, 10,988 deceased donor kidneys transplanted into waitlisted recipients in 2010 were instead allocated to candidates with cPRA≥80% (n=18,004). Each candidate's unacceptable donor HLA antigens had been entered into the allocation system by the transplant center. In simulated match runs, kidneys were allocated sequentially to adult ABO identical or permissible candidates with cPRA 100%, 99%, 98%, etc. to 80%. Allocations were restricted to donor/recipient pairs with negative virtual crossmatches. The simulation indicated that 2111 of 10,988 kidneys (19.2%) would have been allocated to patients with cPRA 100% versus 74 of 10,988 (0.7%) that were actually transplanted. Of cPRA 100% candidates, 74% were predicted to be compatible with an average of six deceased donors; the remaining 26% seemed to be incompatible with every deceased donor organ that entered the system. Of kidneys actually allocated to cPRA 100% candidates in 2010, 66% (49 of 74) were six-antigen HLA matched/zero-antigen mismatched (HLA-A, -B, and -DR) with their recipients versus only 11% (237 of 2111) in the simulation. The simulation predicted that 10,356 of 14,433 (72%) candidates with cPRA 90%-100% could be allocated an organ compared with 7.3% who actually underwent transplant. Data in this simulation are consistent with early results of the new KAS; specifically, nearly 20% of deceased donor kidneys were (virtually) compatible with cPRA 100% candidates. Although most of these candidates were predicted to be compatible with multiple donors, approximately one-quarter are unlikely to receive a single offer. Copyright © 2016 by the

  4. Studies of the chemical basis of the origin of protein synthesis Initiation and direction of peptide growth

    NASA Technical Reports Server (NTRS)

    Mullins, D. W., Jr.; Lacey, J. C., Jr.

    1980-01-01

    The data presented in this paper show that the ease of nonenzymatic activation of carboxylic acids by ATP at pH 5 varies directly with the pKa of the carboxyl group, and is consistent with the idea that it is the protonated form of the carboxyl group which participates in the activation reaction. Consequently, since most N-blocked amino acids have higher pKas than do their unblocked forms, they are activated more readily, and it has been demonstrated that this principle applies to peptides as well, which are activated more rapidly than single amino acids. It is proposed that this fact may be partly responsible for the origin of two important features still observed in contemporary protein synthesis: (1) initiation in prokaryotes is accomplished with an N-blocked amino acid, and (2) elongation in all living systems occurs at the carboxyl end of the growing peptide.

  5. Binomial moments of the distance distribution and the probability of undetected error

    SciTech Connect

    Barg, A.; Ashikhmin, A.

    1998-09-01

    In [1] K.A.S. Abdel-Ghaffar derives a lower bound on the probability of undetected error for unrestricted codes. The proof relies implicitly on the binomial moments of the distance distribution of the code. The authors use the fact that these moments count the size of subcodes of the code to give a very simple proof of the bound in [1] by showing that it is essentially equivalent to the Singleton bound. They discuss some combinatorial connections revealed by this proof. They also discuss some improvements of this bound. Finally, they analyze asymptotics. They show that an upper bound on the undetected error exponent that corresponds to the bound of [1] improves known bounds on this function.

  6. A thermogravimetric analysis of the combustion kinetics of karanja (Pongamia pinnata) fruit hulls char.

    PubMed

    Islam, Md Azharul; Auta, M; Kabir, G; Hameed, B H

    2016-01-01

    The combustion characteristics of Karanj fruit hulls char (KFH-char) was investigated with thermogravimetry analysis (TGA). The TGA outlined the char combustion thermographs at a different heating rate and isoconversional methods expressed the combustion kinetics. The Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods authenticated the char average activation energy at 62.13 and 68.53kJ/mol respectively, enough to derive the char to burnout. However, the Coats-Redfern method verified the char combustion via complex multi-step mechanism; the second stage mechanism has 135kJ/mol average activation energy. The TGA thermographs and kinetic parameters revealed the adequacy of the KFH-char as fuel substrate than its precursor, Karanj fruit hulls (KFH). Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. γ-Irradiation effects on the non-isothermal decomposition of strontium nitrate by model-free and model-fitting methods

    NASA Astrophysics Data System (ADS)

    Culas, Sunil; Samuel, Jadu

    2013-05-01

    The kinetics of the thermal decomposition of untreated and γ-irradiated strontium nitrate, Sr(NO3)2 was studied under non-isothermal conditions at different heating rates (5, 10, 15 and 20 °C min-1) in nitrogen atmosphere. The data were analysed using both isoconversional and non-isoconversional methods. The activation energies were calculated by Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Friedman (FR) methods. The results show that the irradiation enhances the decomposition and the effect increases with the irradiation dose. The activation energy decreases on irradiation. The appropriate conversion model for the thermal decomposition process selected by means of the master-plot method agrees with three-dimensional diffusion model (D3 mechanism), g(α)=[1-(1-α)1/3]2 for both untreated and irradiated salts at all heating rates.

  8. Proton affinity of the histidine-tryptophan cluster motif from the influenza A virus from ab initio molecular dynamics

    NASA Astrophysics Data System (ADS)

    Bankura, Arindam; Klein, Michael L.; Carnevale, Vincenzo

    2013-08-01

    Ab initio molecular dynamics calculations have been used to compare and contrast the deprotonation reaction of a histidine residue in aqueous solution with the situation arising in a histidine-tryptophan cluster. The latter is used as a model of the proton storage unit present in the pore of the M2 proton conducting ion channel. We compute potentials of mean force for the dissociation of a proton from the Nδ and Nɛ positions of the imidazole group to estimate the pKas. Anticipating our results, we will see that the estimated pKa for the first protonation event of the M2 channel is in good agreement with experimental estimates. Surprisingly, despite the fact that the histidine is partially desolvated in the M2 channel, the affinity for protons is similar to that of a histidine in aqueous solution. Importantly, the electrostatic environment provided by the indoles is responsible for the stabilization of the charged imidazolium.

  9. Keratoacanthoma in Japanese Hawaiians in Kauai, Hawaii.

    PubMed

    Reizner, G T; Chuang, T Y; Elpern, D J; Stone, J L; Farmer, E R

    1995-12-01

    This is the first incidence report of keratoacanthoma (KA) in a Japanese ethnic population. The study was designed as a 5-year prospective incidence study using an island-wide survey of Japanese residents in Kauai, Hawaii, during the years 1983 through 1987. Eleven Japanese residents of Kauai, three men and eight women, had KA. The crude incidence is 22.1 per 100,000 Japanese Kauaiian population. Two thirds of the lesions were on the extremities. No recurrence was noted, but a nonmelanoma skin cancer developed in some patients. The incidence of KA in a Japanese ethnic population is not low. Ultraviolet light exposure must, in part, contribute to the development of KA. This is supported by fact that the incidence of KA in Japanese residents in Kauai is much higher than in Japan and that most of the KAS appear on exposed skin.

  10. Some features of the technogenic pollution of the Kara Sea, with the example of the sunken nuclear submarine K-27

    NASA Astrophysics Data System (ADS)

    Dmitrievskiy, N. N.; Nikiforov, S. L.; Lobkovsky, L. I.; Ananiev, R. A.

    2015-11-01

    This article discusses the results of offshore operations undertaken during a cruise of the R/V Professor Shtokman (2013) during an expedition in the fjord Stepovoi of the Novaya Zemlya Archipelago k]where the nuclear submarine (NPS) K-27 was scuttled in 1981 k]An echo sounding of her hull showed signs of water destratification k]which may be caused by turbulence from gas or heat flows outgoing from the hull k]According to the hypothesis of the author k]the presence of the reactors and radioactive nuclear fuel remnants may lead to the continued heating of the inner cavities of the submarine and k]as a consequence k]to constant heat flow from its surface k]which is an obvious danger k]including risks associated with plans to refloat and transport the submarine for the further dismantlement.

  11. Thermogravimetric analysis of co-combustion between microalgae and textile dyeing sludge.

    PubMed

    Peng, Xiaowei; Ma, Xiaoqian; Xu, Zhibin

    2015-03-01

    The synergistic interaction and kinetics of microalgae, textile dyeing sludge and their blends were investigated under combustion condition by thermogravimetric analysis. The textile dyeing sludge was blended with microalgae in the range of 10-90wt.% to investigate their co-combustion behavior. Results showed that the synergistic interaction between microalgae and textile dyeing sludge improved the char catalytic effect and alkali metals melt-induced effect on the decomposition of textile dyeing sludge residue at high temperature of 530-800°C. As the heating rate increasing, the entire combustion process was delayed but the combustion intensity was enhanced. The lowest average activation energy was obtained when the percentage of microalgae was 60%, which was 227.1kJ/mol by OFW and 227.4kJ/mol by KAS, respectively.

  12. Metal accumulations in different tissues of cuttlefish (Sepia officinalis L., 1758) in the Eastern Mediterranean coasts of Turkey.

    PubMed

    Duysak, Önder; Uğurlu, Erkan

    2017-04-01

    In this study, metal concentration levels (Cd, Co, Cr, Ni, and Pb) were investigated in the gill, hepatopancreas, ovary, testis, and mantle of the male and female cuttlefish Sepia officinalis in various stations (Iskenderun, Antalya, Kas, Gazipasa, and Anamur) in Mediterranean coasts of Turkey. Hepatopancreas tissue was a better indicator in terms of heavy metal concentration compared to the other tissues. In general, Cd, Co, Cr, Ni, and Pb accumulation for the male was found more than that of the female, whereas Cd and Ni accumulation was found higher in the female. There was a relationship among the metals in the form of Co > Pb > Ni > Cd > Cr in the mantle tissue. The Pb concentration over the recommended limits was found in cuttlefish of Anamur, Antalya, and Iskenderun stations.

  13. Thermal analysis and luminescence of phospho-tellurite glass doped with NdF3

    NASA Astrophysics Data System (ADS)

    Iwanowicz, Kamil; Dorosz, Dominik; Żmojda, Jacek; Kochanowicz, Marcin

    2015-09-01

    In the paper thermal and luminescence properties of phospho-tellurite glass and glass after thermal treatment doped with NdF3 were presented. The crystallization kinetic of the main crystallization peaks of glass was investigated using differential scanning calorimetry (DSC). The value of the activation energy for crystalline phase (Ec 54,21 +/- 5 kJ mol-1) was calculated using Ozawa-Flynn-Wall (OFW), Kissinger-Akahira-Sunose (KAS), Starink and Tang methods. The glass-ceramic was obtained by heat treatment method. The luminescence transitions from levels 4F5/2 --> 4I9/2 (878 nm), 4F3/2-->4I11/2 (1058 nm), and 4F3/2 --> 4I13/2 (1330 nm) in glass and glass-ceramic doped NdF3 were compered.

  14. Co-pyrolysis characteristics of microalgae Chlorella vulgaris and coal through TGA.

    PubMed

    Chen, Chunxiang; Ma, Xiaoqian; He, Yao

    2012-08-01

    To find out an alternative of coal saving, a kind of microalgae, Chlorella vulgaris (C. vulgaris) which is widespread in fresh water was introduced into coal pyrolysis process. In this work, the pyrolysis experiments of C. vulgaris and coal blend (CCB) were carried out by TGA, and those of C. vulgaris and coal were also taken respectively as control groups. It was found that: the TG and DTG profiles of CCB were similar to C. vulgaris, but different from coal under various blending ratios; DTG profiles of CCB were different at several heating rates; interaction was observed between the solid phases of CCB; kinetic triplets were determined by the Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), and master-plots method, respectively. The results provide a reference for further study on co-pyrolysis of microalgae and coal to a certain extent. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

  15. Studies of the chemical basis of the origin of protein synthesis Initiation and direction of peptide growth

    NASA Technical Reports Server (NTRS)

    Mullins, D. W., Jr.; Lacey, J. C., Jr.

    1980-01-01

    The data presented in this paper show that the ease of nonenzymatic activation of carboxylic acids by ATP at pH 5 varies directly with the pKa of the carboxyl group, and is consistent with the idea that it is the protonated form of the carboxyl group which participates in the activation reaction. Consequently, since most N-blocked amino acids have higher pKas than do their unblocked forms, they are activated more readily, and it has been demonstrated that this principle applies to peptides as well, which are activated more rapidly than single amino acids. It is proposed that this fact may be partly responsible for the origin of two important features still observed in contemporary protein synthesis: (1) initiation in prokaryotes is accomplished with an N-blocked amino acid, and (2) elongation in all living systems occurs at the carboxyl end of the growing peptide.

  16. Current ramp-up with lower hybrid current drive in EAST

    NASA Astrophysics Data System (ADS)

    Ding, B. J.; Li, M. H.; Fisch, N. J.; Qin, H.; Li, J. G.; Wilson, J. R.; Kong, E. H.; Zhang, L.; Wei, W.; Li, Y. C.; Wang, M.; Xu, H. D.; Gong, X. Z.; Shen, B.; Liu, F. K.; Shan, J. F.

    2012-12-01

    More economical fusion reactors might be enabled through the cyclic operation of lower hybrid current drive. The first stage of cyclic operation would be to ramp up the plasma current with lower hybrid waves alone in low-density plasma. Such a current ramp-up was carried out successfully on the EAST tokamak. The plasma current was ramped up with a time-averaged rate of 18 kA/s with lower hybrid (LH) power. The average conversion efficiency Pel/PLH was about 3%. Over a transient phase, faster ramp-up was obtained. These experiments feature a separate measurement of the L/R time at the time of current ramp up.

  17. The Variability of the Marine Atmospheric Boundary Layer in the Greenland Sea Marginal Ice Zone - A Case Study

    DTIC Science & Technology

    1988-12-01

    B. DATA PROCESSIN G ....................................... 15 IV. FLOW REG IM E STUDIES .................................... 17 A. FLOW REGIME...8217 simrie t j Vu l’cs~o.:’ k~LIx P A L.e and Mlr. Peter Guet tur their guid’ijt:C n01 .tIJ r’:~ g ~cL c reseatrch. 1 heir ui~tan cxznd atc:tuor, to detail...GENERAL The A~rctic rel:0a h kas n e~nc .rae 1tf’ t !tex’ ade . due larizel% to the %eair.L fur u.rnxTh ’ I ’ \\. enere’ ree-ourL0, such AN a11 and g

  18. A DFT investigation of base-catalyzed β-elimination reactions in water solution for systems activated by the pyridine ring: Theory vs. experiment

    NASA Astrophysics Data System (ADS)

    Mosconi, Edoardo; De Angelis, Filippo; Tarantelli, Francesco; Alunni, Sergio; Sgamellotti, Antonio

    2008-07-01

    We report a theoretical investigation of β-elimination reactions in systems activated by the pyridine ring. The investigated reaction, the acetohydroxamate-induced β-elimination in protonated N-[2-(2-pyridyl)ethyl]quinuclidinium, offers a unique opportunity to test computational methodologies since detailed kinetic experimental data are available. We calculated the p Kas of the acetohydroxamic acid and the substrate and thoroughly characterized the reactive free-energy profile. The reaction proceeds via a stable carbanion intermediate. Except a discrepancy in the reproduction of the p Ka of the acetohydroxamic acid, the calculated free-energy profile is in excellent agreement with the experiment, showing the general reliability of the present approach.

  19. Pyrolysis kinetics of hazelnut husk using thermogravimetric analysis.

    PubMed

    Ceylan, Selim; Topçu, Yıldıray

    2014-03-01

    This study aims at investigating physicochemical properties and pyrolysis kinetics of hazelnut husk, an abundant agricultural waste in Turkey. The physicochemical properties were determined by bomb calorimeter, elemental analysis and FT-IR spectroscopy. Physicochemical analysis results showed that hazelnut husk has a high calorimetric value and high volatile matter content. Pyrolysis experiments were carried out in a thermogravimetric analyzer under inert conditions and operated at different heating rates (5, 10, 20°C/min). Three different kinetic models, the iso-conversional Kissinger-Akahira-Sunose (KAS) and Ozawa-Flynn-Wall (OFW) models and Coats-Redfern method were applied on TGA data of hazelnut husk to calculate the kinetic parameters including activation energy, pre-exponential factor and reaction order. Simulation of hazelnut husk pyrolysis using data obtained from TGA analysis showed good agreement with experimental data. Combining with physicochemical properties, it was concluded that this biomass can become useful source of energy or chemicals.

  20. Design of a 28 MW pulse facility for testing superconducting coils to several hundred megajoules capacity

    SciTech Connect

    Vogel, H.F.

    1980-01-01

    Railway traction motors are available in unit sizes convenient for installation and series-parallel grouping. They are rugged. Industry builds and refurbishes them with good economy and in quantities replenishing the rolling stock. We find them well suited for reversing the current in a superconducting winding. We focus on a pulsed energy of 20 to 100 MJ, discussing our analysis and facility planning. Limitations are imposed by the following maximum numbers tolerated by the motor - pulsed current of 3.0 to 3.5 kA, current change of 40 kA/s, and pulsed voltage of 1.8 kV. Hence, the number of machines needed in parallel follows from the coil current and its rate of change. The number in series is determined by the voltage. The power transfer is limited by the torsional strength of the motor shaft to a value affected by the flywheel mass.

  1. Pyrolytic and Kinetic Characteristics of the Thermal Decomposition of Perilla frutescens Polysaccharide

    PubMed Central

    Zhou, Quancheng; Sheng, Guihua

    2012-01-01

    The thermal decomposition of Perilla frutescens polysaccharide was examined by thermogravimetry, differential thermogravimetry, and differential thermal analysis. The results showed that the mass loss of the substance proceeded in three steps. The first stage can be attributed to the expulsion of the water from ambient temperature to 182°C. The second stage corresponded to devolatilization from 182°C to 439°C. The residue slowly degraded in the third stage. The weight loss in air is faster than that in nitrogen, because the oxygen in air accelerated the pyrolytic reaction speed reaction. The heating rate significantly affected the pyrolysis of the sample. Similar activation energies of the degradation process (210–211 kJ mol−1) were obtained by the FWO, KAS, and Popescu techniques. According to Popescu mechanism functions, the possible kinetic model was estimated to be Avrami–Erofeev 20 g(α) = [−ln(1–α)]4. PMID:23300715

  2. Apamin-sensitive potassium current modulates action potential duration restitution and arrhythmogenesis of failing rabbit ventricles.

    PubMed

    Hsieh, Yu-Cheng; Chang, Po-Cheng; Hsueh, Chia-Hsiang; Lee, Young Soo; Shen, Changyu; Weiss, James N; Chen, Zhenhui; Ai, Tomohiko; Lin, Shien-Fong; Chen, Peng-Sheng

    2013-04-01

    Apamin-sensitive K currents (I(KAS)) are upregulated in heart failure. We hypothesize that apamin can flatten action potential duration restitution (APDR) curve and can reduce ventricular fibrillation duration in failing ventricles. We simultaneously mapped membrane potential and intracellular Ca (Ca(i)) in 7 rabbit hearts with pacing-induced heart failure and in 7 normal hearts. A dynamic pacing protocol was used to determine APDR at baseline and after apamin (100 nmol/L) infusion. Apamin did not change APD(80) in normal ventricles, but prolonged APD(80) in failing ventricles at either long (≥300 ms) or short (≤170 ms) pacing cycle length, but not at intermediate pacing cycle length. The maximal slope of APDR curve was 2.03 (95% confidence interval, 1.73-2.32) in failing ventricles and 1.26 (95% confidence interval, 1.13-1.40) in normal ventricles at baseline (P=0.002). After apamin administration, the maximal slope of APDR in failing ventricles decreased to 1.43 (95% confidence interval, 1.01-1.84; P=0.018), whereas no significant changes were observed in normal ventricles. During ventricular fibrillation in failing ventricles, the number of phase singularities (baseline versus apamin, 4.0 versus 2.5), dominant frequency (13.0 versus 10.0 Hz), and ventricular fibrillation duration (160 versus 80 s) were all significantly (P<0.05) decreased by apamin. Apamin prolongs APD at long and short, but not at intermediate pacing cycle length in failing ventricles. I(KAS) upregulation may be antiarrhythmic by preserving the repolarization reserve at slow heart rate, but is proarrhythmic by steepening the slope of APDR curve, which promotes the generation and maintenance of ventricular fibrillation.

  3. Ethylene is involved in root phosphorus remobilization in rice (Oryza sativa) by regulating cell-wall pectin and enhancing phosphate translocation to shoots.

    PubMed

    Zhu, Xiao Fang; Zhu, Chun Quan; Zhao, Xu Sheng; Zheng, Shao Jian; Shen, Ren Fang

    2016-05-02

    Plants are able to grow under phosphorus (P)-deficient conditions by coordinating Pi acquisition, translocation from roots to shoots and remobilization within the plant. Previous reports have demonstrated that cell-wall pectin contributes greatly to rice cell-wall Pi re-utilization under P-deficient conditions, but whether other factors such as ethylene also affect the pectin-remobilizing capacity remains unclear. Two rice cultivars, 'Nipponbare' (Nip) and 'Kasalath' (Kas) were cultured in the +P (complete nutrient solution), -P (withdrawing P from the complete nutrient solution), +P+ACC (1-amino-cyclopropane-1-carboxylic acid, an ethylene precursor, adding 1 μm ACC to the complete nutrient solution) and -P+ACC (adding 1 μm ACC to -P nutrient solution) nutrient solutions for 7 d. After 7 d -P treatment, there was clearly more soluble P in Nip root and shoot, accompanied by additional production of ethylene in Nip root compared with Kas. Under P-deficient conditions, addition of ACC significantly increased the cell-wall pectin content and decreased cell-wall retained P, and thus more soluble P was released to the root and translocated to the shoot, which was mediated by the expression of the P deficiency- responsive gene OsPT2, which also strongly induced by ACC treatment under both P-sufficient and P-deficient conditions. Ethylene positively regulates pectin content and expression of OsPT2, which ultimately makes more P available by facilitating the solubilization of P fixed in the cell wall and its translocation to the shoot. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  4. Is there a role for ketoacid supplements in the management of CKD?

    PubMed

    Shah, Anuja P; Kalantar-Zadeh, Kamyar; Kopple, Joel D

    2015-05-01

    Ketoacid (KA) analogues of essential amino acids (EAAs) provide several potential advantages for people with advanced chronic kidney disease (CKD). Because KAs lack the amino group bound to the α carbon of an amino acid, they can be converted to their respective amino acids without providing additional nitrogen. It has been well established that a diet with 0.3 to 0.4 g of protein per kilogram per day that is supplemented with KAs and EAAs reduces the generation of potentially toxic metabolic products, as well as the burden of potassium, phosphorus, and possibly sodium, while still providing calcium. These KA/EAA-supplemented very-low-protein diets (VLPDs) can maintain good nutrition, but the appropriate dose of the KA/EAA supplement has not been established. Thus, a KA/EAA dose-response study for good nutrition clearly is needed. Similarly, the composition of the KA/EAA supplement needs to be reexamined; for example, some KA/EAA preparations contain neither the EAA phenylalanine nor its analogue. Indications concerning when to inaugurate a KA/EAA-supplemented VLPD therapy also are unclear. Evidence strongly suggests that these diets can delay the need for maintenance dialysis therapy, but whether they slow the loss of glomerular filtration rate in patients with CKD is less clear, particularly in this era of more vigorous blood pressure control and use of angiotensin/aldosterone blockade. Some clinicians prescribe KA/EAA supplements for patients with CKD or treated with maintenance dialysis, but with diets that have much higher protein levels than the VLPDs in which these supplements have been studied. More research is needed to examine the effectiveness of KA/EAA supplements with higher protein intakes. Copyright © 2015 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

  5. Bohr effect of avian hemoglobins: Quantitative analyses based on the Wyman equation.

    PubMed

    Okonjo, Kehinde O

    2016-12-07

    The Bohr effect data for bar-headed goose, greylag goose and pheasant hemoglobins can be fitted with the Wyman equation for the Bohr effect, but under one proviso: that the pKa of His146β does not change following the T→R quaternary transition. This assumption is based on the x-ray structure of bar-headed goose hemoglobin, which shows that the salt-bridge formed between His146β and Asp94β in human deoxyhemoglobin is not formed in goose deoxyhemoglobin. When the Bohr data for chicken hemoglobin were fitted by making the same assumption, the pKa of the NH3(+) terminal group of Val1α decreased from 7.76 to 6.48 following the T→R transition. When the data were fitted without making any assumption, the pKa of the NH3(+) terminal group increased from 7.57 to 7.77 following the T→R transition. We demonstrate that avian hemoglobin Bohr data are readily fitted with the Wyman equation because avian hemoglobins lack His77β. From curve-fitting to Bohr data we estimate the pKas of the NH3(+) terminal group of Val1α in the R and T states to be 6.33±0.1 and 7.22±0.1, respectively. We provide evidence indicating that these pKas are more accurate than estimates from kinetic studies. Copyright © 2016 Elsevier Ltd. All rights reserved.

  6. A Virtual Mixture Approach to the Study of Multistate Equilibrium: Application to Constant pH Simulation in Explicit Water

    PubMed Central

    Wu, Xiongwu; Brooks, Bernard R.

    2015-01-01

    Chemical and thermodynamic equilibrium of multiple states is a fundamental phenomenon in biology systems and has been the focus of many experimental and computational studies. This work presents a simulation method to directly study the equilibrium of multiple states. This method constructs a virtual mixture of multiple states (VMMS) to sample the conformational space of all chemical states simultaneously. The VMMS system consists of multiple subsystems, one for each state. The subsystem contains a solute and a solvent environment. The solute molecules in all subsystems share the same conformation but have their own solvent environments. Transition between states is implicated by the change of their molar fractions. Simulation of a VMMS system allows efficient calculation of relative free energies of all states, which in turn determine their equilibrium molar fractions. For systems with a large number of state transition sites, an implicit site approximation is introduced to minimize the cost of simulation. A direct application of the VMMS method is for constant pH simulation to study protonation equilibrium. Applying the VMMS method to a heptapeptide of 3 ionizable residues, we calculated the pKas of those residues both with all explicit states and with implicit sites and obtained consistent results. For mouse epidermal growth factor of 9 ionizable groups, our VMMS simulations with implicit sites produced pKas of all 9 ionizable groups and the results agree qualitatively with NMR measurement. This example demonstrates the VMMS method can be applied to systems of a large number of ionizable groups and the computational cost scales linearly with the number of ionizable groups. For one of the most challenging systems in constant pH calculation, SNase Δ+PHS/V66K, our VMMS simulation shows that it is the state-dependent water penetration that causes the large deviation in lysine66’s pKa. PMID:26506245

  7. Nonadherence to Guideline Recommendations for Tympanostomy Tube Insertion in Children Based on Mega-database Claims Analysis.

    PubMed

    Sajisevi, Mirabelle; Schulz, Kristine; Cyr, Derek D; Wojdyla, Daniel; Rosenfeld, Richard M; Tucci, Debara; Witsell, David L

    2017-01-01

    Objective To estimate the nonadherence rate of pressure equalization (tympanostomy) tube (PET) placement in the preceding 3-year period before release of the 2013 American Academy of Otolaryngology-Head and Neck Surgery Foundation clinical practice guideline (CPG). Study Design Analysis of the Truven Health MarketScan Research Databases (2010-2012). Subjects and Methods Medical claims data from 2010 to 2012 were analyzed. Children aged ≤12 years with otitis media (OM)-related diagnoses were identified. Adherence and nonadherence rates for OM and PET placement were analyzed through administrative codes extrapolated from the key action statements (KASs) of the CPG. KASs were aggregated to estimate the overall nonadherence and determine areas for quality improvement. Results A total of 9,726,411 visits with OM-associated codes among 3,710,730 children were identified: 2.9% (80,451 of 3,239,700) were considered nonadherent to KAS 1 because a code for PET placement occurred with a first episode of OM with effusion <3 months; 52.1% (14,534 of 27,913) underwent PET placement for OM with effusion of >3 months and had a concurrent hearing loss code. For those without hearing loss who underwent PET placement, 48.3% (52,921 of 109,583) had a diagnosis code indicating risk for speech, language, or learning problems. For each KAS, we found heterogeneity of computed nonadherence rates by region, age, and season. Conclusion Before guideline dissemination, we found low to moderate rates of nonadherence to guideline recommendation. Deeper analysis of mega-databases could provide better insights for measurement of guideline adherence. The expansion of administrative and clinical databases provides a unique opportunity to investigate the impact of CPGs.

  8. Suppression of fabB Mutation by fabF1 Is Mediated by Transcription Read-through in Shewanella oneidensis.

    PubMed

    Li, Meng; Meng, Qiu; Fu, Huihui; Luo, Qixia; Gao, Haichun

    2016-11-15

    As type II fatty acid synthesis is essential for the growth of Escherichia coli, its many components are regarded as potential targets for novel antibacterial drugs. Among them, β-ketoacyl-acyl carrier protein (ACP) synthase (KAS) FabB is the exclusive factor for elongation of the cis-3-decenoyl-ACP (cis-3-C10-ACP). In our previous study, we presented evidence to suggest that this may not be the case in Shewanella oneidensis, an emerging model gammaproteobacterium renowned for its respiratory versatility. Here, we identified FabF1, another KAS, as a functional replacement for FabB in S. oneidensis In fabB(+) or desA(+) (encoding a desaturase) cells, which are capable of making unsaturated fatty acids (UFA), FabF1 is barely produced. However, UFA auxotroph mutants devoid of both fabB and desA genes can be spontaneously converted to suppressor strains, which no longer require exogenous UFAs for growth. Suppression is caused by a TGTTTT deletion in the region upstream of the fabF1 gene, resulting in enhanced FabF1 production. We further demonstrated that the deletion leads to transcription read-through of the terminator for acpP, an acyl carrier protein gene immediately upstream of fabF1 There are multiple tandem repeats in the region covering the terminator, and the TGTTTT deletion, as well as others, compromises the terminator efficacy. In addition, FabF2 also shows an ability to complement the FabB loss, albeit substantially less effectively than FabF1.

  9. Lactococcus lactis fabH, Encoding β-Ketoacyl-Acyl Carrier Protein Synthase, Can Be Functionally Replaced by the Plasmodium falciparum Congener▿

    PubMed Central

    Du, Yu; Gisselberg, Jolyn E.; Johnson, Jacob D.; Lee, Patricia J.; Prigge, Sean T.; Bachmann, Brian O.

    2010-01-01

    Plasmodium falciparum, in addition to scavenging essential fatty acids from its intra- and intercellular environments, possesses a functional complement of type II fatty acid synthase (FAS) enzymes targeted to the apicoplast organelle. Recent evidence suggests that products of the plasmodial FAS II system may be critical for the parasite's liver-to-blood cycle transition, and it has been speculated that endogenously generated fatty acids may be precursors for essential cofactors, such as lipoate, in the apicoplast. β-Ketoacyl-acyl carrier protein (ACP) synthase III (pfKASIII or FabH) is one of the key enzymes in the initiating steps of the FAS II pathway, possessing two functions in P. falciparum: the decarboxylative thio-Claisen condensation of malonyl-ACP and various acyl coenzymes A (acyl-CoAs; KAS activity) and the acetyl-CoA:ACP transacylase reaction (ACAT). Here, we report the generation and characterization of a hybrid Lactococcus lactis strain that translates pfKASIII instead of L. lactis fabH to initiate fatty acid biosynthesis. The L. lactis expression vector pMG36e was modified for the efficient overexpression of the plasmodial gene in L. lactis. Transcriptional analysis indicated high-efficiency overexpression, and biochemical KAS and ACAT assays confirm these activities in cell extracts. Phenotypically, the L. lactis strain expressing pfKASIII has a growth rate and fatty acid profiles that are comparable to those of the strain complemented with its endogenous gene, suggesting that pfKASIII can use L. lactis ACP as substrate and perform near-normal function in L. lactis cells. This strain may have potential application as a bacterial model for pfKASIII inhibitor prescreening. PMID:20418430

  10. Synthesis and characterization of mRNA cap analogs containing phosphorothioate substitutions that bind tightly to eIF4E and are resistant to the decapping pyrophosphatase DcpS.

    PubMed

    Kowalska, Joanna; Lewdorowicz, Magdalena; Zuberek, Joanna; Grudzien-Nogalska, Ewa; Bojarska, Elzbieta; Stepinski, Janusz; Rhoads, Robert E; Darzynkiewicz, Edward; Davis, Richard E; Jemielity, Jacek

    2008-06-01

    Analogs of the mRNA cap are widely employed to study processes involved in mRNA metabolism as well as being useful in biotechnology and medicinal applications. Here we describe synthesis of six dinucleotide cap analogs bearing a single phosphorothioate modification at either the alpha, beta, or gamma position of the 5',5'-triphosphate chain. Three of them were also modified with methyl groups at the 2'-O position of 7-methylguanosine to produce anti-reverse cap analogs (ARCAs). Due to the presence of stereogenic P centers in the phosphorothioate moieties, each analog was obtained as a mixture of two diastereomers, D1 and D2. The mixtures were resolved by RP HPLC, providing 12 different compounds. Fluorescence quenching experiments were employed to determine the association constant (K(AS)) for complexes of the new analogs with eIF4E. We found that phosphorothioate modifications generally stabilized the complex between eIF4E and the cap analog. The most strongly bound phosphorothioate analog (the D1 isomer of the beta-substituted analog m(7)Gpp(S)pG) was characterized by a K(AS) that was more than fourfold higher than that of its unmodified counterpart (m(7)GpppG). All analogs modified in the gamma position were resistant to hydrolysis by the scavenger decapping pyrophosphatase DcpS from both human and Caenorhabditis elegans sources. The absolute configurations of the diastereomers D1 and D2 of analogs modified at the alpha position (i.e., m(7)Gppp(S)G and m(2) (7,2'-O )Gppp(S)G) were established as S(P) and R(P) , respectively, using enzymatic digestion and correlation with the S(P) and R(P) diastereomers of guanosine 5'-O-(1-thiodiphosphate) (GDPalphaS). The analogs resistant to DcpS act as potent inhibitors of in vitro protein synthesis in rabbit reticulocyte lysates.

  11. Microwave irradiation affects ion pairing in aqueous solutions of alkali halide salts

    NASA Astrophysics Data System (ADS)

    Mohorič, Tomaž; Bren, Urban

    2017-01-01

    Using the molecular dynamics simulations with separate thermostats for translational and rotational degrees of freedom, we investigate the effects of water's rotational motion on the ion pairing of ionic solutes in aqueous solutions. The situation with rotational temperature higher than the translational one, Trot>Ttrs , is mimicking the non-equilibrium effects of microwaves on model solutions of alkali halide salts. The simulations reveal that an increase in the rotational temperature at constant translational temperature exerts significant changes in the structure of the solution. The latter are reflected in increased pairing of the oppositely charged ions, which can be explained by the weaker ability of rotationally excited water to screen and separate the opposite charges. It seems that Collins' law of matching water affinities retains its validity also in the non-equilibrium situation where the rotational temperature exceeds the translational one. On the other hand, the equilibrium effect (i.e., an increase in the solution's overall temperature T ≡Trot = Ttrs) favors the formation of small-small (NaCl), while it has a little effect on large-large (CsI) ion pairs. This is in accordance with water becoming less polar solvent upon a temperature increase. Furthermore, we investigated the effects of excited translational motion of water (and ions) on the ion pairing by increasing the translational temperature, while keeping the rotational one unchanged (i.e., Ttrs>Trot ). Interestingly, in certain cases the faster translational motion causes an increase in correlations. The temperature variations in the like-ion association constants, Kas++ and Kas-, are also examined. Here the situation is more complex but, in most cases, a decrease in the ion pairing is observed.

  12. Geochemical Fate and Transport of Sildenafil and Vardenafil

    NASA Astrophysics Data System (ADS)

    Richter, L.; Boudinot, G.; Vulava, V. M.; Cory, W. C.

    2015-12-01

    The geochemical fate of pharmaceuticals and their degradation products is a developing environmental field. The geologic, chemical, and biological fate of these pollutants has become very relevant with the increase in human population and the resulting increase in pollutant concentrations in the environment. In this study, we focus on sildenafil (SDF) and vardenafil (VDF), active compounds in Viagra and Levitra, respectively, two commonly used erectile dysfunction drugs. The main objective is to determine the sorption potential and transport behavior of these two compounds in natural soils. Both SDF and VDF are complex organic molecules with multiple amine functional groups in their structures. Two types of natural acidic soils (pH≈4.5), an organic-rich soil (7.6% OM) and clay-rich soil (5.1% clay) were used in this study to determine which soil components influence sorption behavior of both compounds. Sorption isotherms measured using batch reactors were nearly linear, but sorption was stronger in soil that contained higher clay content. Both compounds have multiple pKas due to the amine functional groups, the relevant pKas of SDF are 5.97 and 7.27, and those of VDF's are 4.72 and 6.21. These values indicate that these compounds likely behave as cations in soil suspensions and hence were strongly sorbed to negatively-charged clay minerals present in both soils. The clay composition in both soils is predominantly kaolinite with smaller amount of montmorillonite, both of which have a predominantly negative surface charge. Transport experiments using glass chromatography columns indicated that both compounds were more strongly retarded in the clay-rich soils. Breakthrough curves from the transport experiments were modeled using convection-dispersion transport equations. The organic matter in the soil seemed to play a less dominant role in the geochemistry in this study, but is likely to transform both compounds into derivative compounds as seen in other studies.

  13. Overview on mechanisms of isoniazid action and resistance in Mycobacterium tuberculosis.

    PubMed

    Unissa, Ameeruddin Nusrath; Subbian, Selvakumar; Hanna, Luke Elizabeth; Selvakumar, Nagamiah

    2016-11-01

    Isoniazid (INH) is one of the most active compounds used to treat tuberculosis (TB) worldwide. In addition, INH has been used as a prophylactic drug for individuals with latent Mycobacterium tuberculosis (MTB) infection to prevent reactivation of disease. Importantly, the definition of multidrug resistance (MDR) in TB is based on the resistance of MTB strains to INH and rifampicin (RIF). Despite its simple chemical structure, the mechanism of action of INH is very complex and involves several different concepts. Many pathways pertaining to macromolecular synthesis are affected, notably mycolic acid synthesis. The pro-drug INH is activated by catalase-peroxidase (KatG), and the active INH products are targeted by enzymes namely, enoyl acyl carrier protein (ACP) reductase (InhA) and beta-ketoacyl ACP synthase (KasA). In contrast, INH is inactivated by arylamine N-acetyltransferases (NATs). Consequently, the molecular mechanisms of INH resistance involve several genes in multiple biosynthetic networks and pathways. Mutation in the katG gene is the major cause for INH resistance, followed by inhA, ahpC, kasA, ndh, iniABC,fadE, furA, Rv1592c and Rv1772. The recent association of efflux genes with INH resistance has also gained considerable attention. Interestingly, substitutions have also been observed in nat, fabD, and accD recently in resistant isolates. Understanding the mechanisms operating behind INH action and resistance would enable better detection of INH resistance. This information would aid novel drug design strategies. Herein we review all mechanisms known to potentially contribute to the complexity of INH action and mechanisms of resistance in MTB, with insights into methods for detection of INH resistance as well as their limitations.

  14. Differential gene expression at different stages of mesocarp development in high- and low-yielding oil palm.

    PubMed

    Wong, Yick Ching; Teh, Huey Fang; Mebus, Katharina; Ooi, Tony Eng Keong; Kwong, Qi Bin; Koo, Ka Loo; Ong, Chuang Kee; Mayes, Sean; Chew, Fook Tim; Appleton, David R; Kulaveerasingam, Harikrishna

    2017-06-21

    The oil yield trait of oil palm is expected to involve multiple genes, environmental influences and interactions. Many of the underlying mechanisms that contribute to oil yield are still poorly understood. In this study, we used a microarray approach to study the gene expression profiles of mesocarp tissue at different developmental stages, comparing genetically related high- and low- oil yielding palms to identify genes that contributed to the higher oil-yielding palm and might contribute to the wider genetic improvement of oil palm breeding populations. A total of 3412 (2001 annotated) gene candidates were found to be significantly differentially expressed between high- and low-yielding palms at at least one of the different stages of mesocarp development evaluated. Gene Ontologies (GO) enrichment analysis identified 28 significantly enriched GO terms, including regulation of transcription, fatty acid biosynthesis and metabolic processes. These differentially expressed genes comprise several transcription factors, such as, bHLH, Dof zinc finger proteins and MADS box proteins. Several genes involved in glycolysis, TCA, and fatty acid biosynthesis pathways were also found up-regulated in high-yielding oil palm, among them; pyruvate dehydrogenase E1 component Subunit Beta (PDH), ATP-citrate lyase, β- ketoacyl-ACP synthases I (KAS I), β- ketoacyl-ACP synthases III (KAS III) and ketoacyl-ACP reductase (KAR). Sucrose metabolism-related genes such as Invertase, Sucrose Synthase 2 and Sucrose Phosphatase 2 were found to be down-regulated in high-yielding oil palms, compared to the lower yield palms. Our findings indicate that a higher carbon flux (channeled through down-regulation of the Sucrose Synthase 2 pathway) was being utilized by up-regulated genes involved in glycolysis, TCA and fatty acid biosynthesis leading to enhanced oil production in the high-yielding oil palm. These findings are an important stepping stone to understand the processes that lead to

  15. A Virtual Mixture Approach to the Study of Multistate Equilibrium: Application to Constant pH Simulation in Explicit Water.

    PubMed

    Wu, Xiongwu; Brooks, Bernard R

    2015-10-01

    Chemical and thermodynamic equilibrium of multiple states is a fundamental phenomenon in biology systems and has been the focus of many experimental and computational studies. This work presents a simulation method to directly study the equilibrium of multiple states. This method constructs a virtual mixture of multiple states (VMMS) to sample the conformational space of all chemical states simultaneously. The VMMS system consists of multiple subsystems, one for each state. The subsystem contains a solute and a solvent environment. The solute molecules in all subsystems share the same conformation but have their own solvent environments. Transition between states is implicated by the change of their molar fractions. Simulation of a VMMS system allows efficient calculation of relative free energies of all states, which in turn determine their equilibrium molar fractions. For systems with a large number of state transition sites, an implicit site approximation is introduced to minimize the cost of simulation. A direct application of the VMMS method is for constant pH simulation to study protonation equilibrium. Applying the VMMS method to a heptapeptide of 3 ionizable residues, we calculated the pKas of those residues both with all explicit states and with implicit sites and obtained consistent results. For mouse epidermal growth factor of 9 ionizable groups, our VMMS simulations with implicit sites produced pKas of all 9 ionizable groups and the results agree qualitatively with NMR measurement. This example demonstrates the VMMS method can be applied to systems of a large number of ionizable groups and the computational cost scales linearly with the number of ionizable groups. For one of the most challenging systems in constant pH calculation, SNase Δ+PHS/V66K, our VMMS simulation shows that it is the state-dependent water penetration that causes the large deviation in lysine66's pKa.

  16. Kinetics of the iodine- and bromine-mediated transport of halide ions: demonstration of an interfacial complexation mechanism.

    PubMed Central

    Klotz, K H; Benz, R

    1993-01-01

    Stationary and kinetic experiments were performed on lipid bilayer membranes to study the mechanism of iodine- and bromine-mediated halide transport in detail. The stationary conductance data suggested that four different 1:1 complexes between I2 and Br2 and the halides I- and Br- were responsible for the observed conductance increase by iodine and bromine (I3-, I2Br-, Br2I-, and Br3-). Charge pulse experiments allowed the further elucidation of the transport mechanism. Only two of three exponential voltage relaxations predicted by the Läuger model could be resolved under all experimental conditions. This means that either the heterogeneous complexation reactions kR (association) and kD (dissociation) were too fast to be resolved or that the neutral carriers were always in equilibrium within the membrane. Experiments at different carrier and halide concentrations suggested that the translocation of the neutral carrier is much faster than the other processes involved in carrier-mediated ion transport. The model was modified accordingly. From the charge pulse data at different halide concentrations, the translocation rate constant of the complexed carriers, kAS, the dissociation constant, kD, and the total surface concentration of charged carriers, NAS, could be evaluated from one single charge pulse experiment. The association rate of the complex, kR, could be obtained in some cases from the plot of the stationary conductance data as a function of the halide concentration in the aqueous phase. The translocation rate constant, kAS, of the different complexes is a function of the image force and of the Born charging energy. It increases 5000-fold from Br3- to I3- because of an enlarged ion radius. PMID:8312500

  17. An Induction Motor Based Wind Turbine Emulator

    NASA Astrophysics Data System (ADS)

    Sokolovs, A.; Grigans, L.; Kamolins, E.; Voitkans, J.

    2014-04-01

    The authors present a small-scale wind turbine emulator based on the AC drive system and discuss the methods for power coefficient calculation. In the work, the experimental set-up consisting of an AC induction motor, a frequency converter, a synchronous permanent magnet generator, a DC-DC boost converter and DC load was simulated and tested using real-life equipment. The experimentally obtained wind turbine power and torque diagrams using the emulator are in a good agreement with the theoretical ones. Šajā rakstā parādīta mazas jaudas vēja turbīnas emulatora izveide ar maiņstrāvas piedziņas sistēmu, kā arī analizētas vairākas turbīnas jaudas koeficienta analītiskās aprēķina metodes. Vēja turbīnas emulatora eksperimentālais stends, kas sastāv no asinhronā elektromotora, frekvenču pārveidotāja, sinhronā pastāvīgo magnētu ģeneratora, līdzstrāvas paaugstinošā pārveidotāja un slodzes, tika pārbaudīts gan simulēšanas vidē, gan uz reālām iekārtām. Eksperimentāli iegūtās vēja turbīnas emulatora jaudas un momenta diagrammas ir salīdzinātas ar teorētiskajām.

  18. Tumor-associated macrophages infiltrate plasmacytomas and can serve as cell carriers for oncolytic measles virotherapy of disseminated myeloma

    PubMed Central

    Peng, Kah-Whye; Dogan, Ahmet; Vrana, Julie; Liu, Chunsheng; Ong, Hooi T.; Kumar, Shaji; Dispenzieri, Angela; Dietz, Allan B.; Russell, Stephen J.

    2009-01-01

    In multiple myeloma, some of the neoplastic plasma cells are diffusely dispersed among the normal bone marrow cells (bone marrow resident), whereas others are located in discrete, well-vascularized solid tumors (plasmacytomas) that may originate in bone or soft tissue. Interactions between bone marrow-resident myeloma cells and bone marrow stromal cells (BMSCs) are important determinants of myeloma pathogenesis. However, little is known of the factors sustaining myeloma growth and cell viability at the centers of expanding plasmacytomas, where there are no BMSCs. Histologic sections of 22 plasmacytomas from myeloma patients were examined after immunostaining. Abundant CD68+, CD163+, S100-negative macrophage infiltrates were identified in all tumors, accompanied by scattered collections of CD3+ T lymphocytes. The CD68+ tumor-associated macrophages (TAM) accounted for 2– 12% of nucleated cells and were evenly distributed through the parenchyma. The TAM generally had dendritic morphology, and each dendrite was in close contact with multiple plasma cells. In some cases, the TAM were strikingly clustered around CD34+ blood vessels. To determine whether cells of the monocytic lineage might be exploitable as carriers for delivery of therapeutic agents to plasmacytomas, primary human CD14+ cells were infected with oncolytic measles virus and administered intravenously to mice bearing KAS6/1 human myeloma xenografts. The cell carriers localized to KAS6/1 tumors, where they transferred MV infection to myeloma cells and prolonged the survival of mice bearing disseminated human myeloma disease. Thus, TAM are a universal stromal component of the plasmacytomas of myeloma patients and may offer a promising new target for therapeutic exploitation. PMID:19507209

  19. Calorimetric investigation of proton linkage by monitoring both the enthalpy and association constant of binding: application to the interaction of the Src SH2 domain with a high-affinity tyrosyl phosphopeptide.

    PubMed

    Bradshaw, J M; Waksman, G

    1998-11-03

    The binding of Src homology 2 (SH2) domains to tyrosyl phosphopeptides depends on electrostatic interactions between the phosphotyrosine and its binding site. To probe the role of these interactions, we have used isothermal titration calorimetry to study the pH dependence of the binding of the SH2 domain of the Src kinase to a high-affinity tyrosyl phosphopeptide. Two independent approaches were employed. In a first series of experiments that focused on determining the peptide's association constant between pH 5.0 and 9.0, two ionizable groups were characterized. One group, with free and bound pKas of 6.2 and 4.4, respectively, could be identified as the phosphate in the phosphotyrosine while the other group, with free and bound pKas of 8.2 and 8.5, respectively, could be only tentatively assigned to a cysteine in the phosphotyrosine binding pocket. Further information on the linkage between peptide binding and protonation of the phosphotyrosine was obtained from a second series of experiments, which focused on determining the peptide binding enthalpy at low values of pH in several buffers with different ionization enthalpies. These data provided free and bound pKa values for the phosphotyrosine identical to those derived from the first series of experiments, and hence demonstrated for the first time that the two approaches provide identical information regarding proton linkage. In addition, the second series of experiments also determined the intrinsic enthalpy of binding of both the protonated and deprotonated phosphate forms of the peptide. These two sets of experiments provided a complete energetic profile of the linkage between phosphate ionization and peptide binding. From this profile, it was determined that the PO32- form of the peptide binds 2.3 kcal mol-1 more favorably than the PO3H1- form due entirely to a more favorable entropy of binding.

  20. Differences in the immobilization of arsenite and arsenate by calcite

    NASA Astrophysics Data System (ADS)

    Yokoyama, Yuka; Tanaka, Kazuya; Takahashi, Yoshio

    2012-08-01

    The sorption and coprecipitation experiments of arsenic (As) with calcite coupled with determinations of the chemical state of As both in the reaction fluid and in calcite were conducted to investigate the influence of the As oxidation state on its immobilization into calcite. The oxidation states of As in calcite and water were determined via As K-edge XANES and HPLC-ICP-MS analysis, respectively. The results of the sorption experiments at pH 8.2 show that only As(V) is distributed to calcite regardless of the As oxidation state in the solution. In coprecipitation experiments, As(V) is preferentially incorporated into calcite over a wide range of pH (7-12). On the other hand, the incorporation of As(III) into calcite is not observed at circumneutral pH. This difference between As(III) and As(V) is attributed to the fact that their dissolved species are neutral vs. negatively charged, respectively, at circumneutral pH (arsenite as H3AsO3; arsenate as H2AsO4- or HAsO42-). As the pH increases (>9), up to 33% of As(III)/Astotal ratio is partitioned into calcite or a precursor of calcite (metastable vaterite formed during the early stage of precipitation). The higher interaction of As with calcite at an alkaline pH compared with circumneutral pH is due to the negative charge of As(III) at alkaline pH. However, the As(III)/Astotal ratio decreases as time progresses and only As(V) can be found finally in calcite. The ratio of distribution coefficients of As(III) and As(V) into calcite (KAs(V)/KAs(III)) at pH ˜7 is larger than 2.1 × 103, suggesting that the oxidation state of As is a significant issue in considering the interaction between As and calcite in groundwater. Moreover, low KAs(III) shows that the sequestration of As via coprecipitation with calcite is not an important chemical process under reducing conditions, such as in the groundwaters in Bangladesh and other As-contaminated areas where As(III) is the dominant dissolved species of As. In the system spiked

  1. Ni-Al Protective Coating of Steel Electrodes in Dc Electrolysis for Hydrogen Production / Ni-Al Pārklājuma Ietekme Uz Tērauda Elektrodiem Līdzstrāvas Elektrolīzē Ūdeņraža Ražošanai

    NASA Astrophysics Data System (ADS)

    Aizpurietis, P.; Vanags, M.; Kleperis, J.; Bajars, G.

    2013-04-01

    Hydrogen can be a good alternative to fossil fuels under the conditions of world's crisis as an effective energy carrier derived from renewable resources. Among all the known methods of hydrogen production, water electrolysis gives the ecologically purest hydrogen, so it is of importance to maximize the efficiency of this process. The authors consider the influence of plasma sprayed Ni-Al protective coating of 316L steel anode-cathode electrodes in DC electrolysis. In a long-term (24 h) process the anode corrodes strongly, losing Cr and Ni ions which are transferred to the electrolyte, while only minor corrosion of the cathode occurs. At the same time, the composition of anode and cathode electrodes protected by Ni-Al coating changes only slightly during a prolonged electrolysis. As the voltammetry and Tafel plots evidence, the Ni-Al coating protects both the anode and cathode from the corrosion and reduces the potential of hydrogen evolution. The results obtained show that such a coating works best in the case of steel electrodes. Darbā pētīts, kā līdzstrāvas elektrolīzē tērauda 316L elektrodus (anods un katods) ietekmē ar plazmas izputināšanas metodi iegūts Ni-Al pārklājums. Tikko uznestam pārklājumam ir mikrostrukturēta virsma, kas kodināšanas laikā mainās, gan pēc reljefa, gan elementu sastāva. Veicot ilgstošu (24 stundas elektrolīzi), atrasts, ka tikai tērauda elektrods anoda lomā intensīvi korodē un zaudē hroma un niķeļa jonus, kas pāriet elektrolītā, turpretī katods mainās relatīvi maz. Pārklājums Ni-Al pēc uznešanas tiek kodināts karstā sārmā, kad tiek izšķīdināta daļa sastāvā esošo elementu (Al, Si, Cd), bet ilgstošas elektrolīzes laikā pārklājuma sastāvs mainās maz gan anodam, gan katodam. Elektrodu elektroķīmiskie raksturlielumi noteikti ar voltamperometrijas un Tāfeļa līkņu analīzes metodēm. Atrasts, ka Ni-Al pārklājums aizsargā gan anodu, gan katodu no korozijas un samazina

  2. Fused Deposition Modelling as Rapid Prototyping for Structural Material Improvement: Analytical Solution / Ātrās Prototipēšanas Ar Kausēšanas Metodi Strukturālā Uzlabojuma Analītisks Risinājums

    NASA Astrophysics Data System (ADS)

    Brensons, I.; Polukoshko, S.

    2013-10-01

    Fused deposition modelling (FDM) is one of the most effective rapid prototyping (RP) techniques due to its low cost, available materials and versatility. In FDM, a part of material (usually plastic) is made by heating this material to the molten state, and from the melt it is extruded through a nozzle and deposited on a surface. In the article, an alternative RP method is considered for improvement of the mechanical properties of a rapid prototype. The authors propose an analytical solution which allows for achievement of this purpose via advanced technologies. The base materials applied in RP technology can be combined with liquid resin which solidifies after a definite time. This makes it possible to create a channel through the prototype and fill it with another material having better mechanical properties. The optimal channel sizes can be chosen in order to raise the strength of material parts. Darbā tiek apskatīts ātrās prototipēšanas veids, kura pamatā ir detaļas veidošana, izmantojot kausētu materiālu parasti plastmasu. Šī detaļu veidošanas metode ir kļuvusi par vienu no visizplatītākajām tās zemo izmaksu, pieejamo materiālu un daudzpusības dēļ. Šī raksta mērķis ir izpētīt alternatīvu veidu, kā uzlabot prototipu mehāniskās īpašības, tādējādi palielinot printētu detaļu izmantošanu kā gala produktu. Raksts piedāvā analītisku risinājumu, kā uzlabot ātro prototipu mehāniskās īpašības, uzlabojot tehnoloģiskos procesus, kas iesaistīti detaļu izgatavošanā. Darba pamatā tiek izmantota 3D printēšanas tehnoloģijas iespēja veidot iekšējus kanālus bez ģeometriskiem ierobežojumiem, kā rezultātā ir iespējams izveidot iekšēju kanālu shēmu, ko pēc tam piepilda ar citu materiālu, kam ir labākas mehāniskās īpašības kā pamata materiālam. Pildīšanai izmantotais materiāls ir epoksīda sveķi, kas pieļauj vieglu iepildīšanu šķidrā fāzē, un sniedz labas mehāniskās īpašības p

  3. Triassic arc-derived detritus in the Triassic Karakaya accretionary complex was not derived from either the S Eurasian margin (Istanbul terrane) or the N Gondwana margin (Taurides)

    NASA Astrophysics Data System (ADS)

    Ustaömer, Timur; Ayda Ustaömer, Petek; Robertson, Alastair H. F.; Gerdes, Axel; Zulauf, Gernold

    2014-05-01

    We present new U-Pb zircon source age data for Upper Triassic sandstones of the Istanbul Terrane (S Eurasian margin) and also for Triassic sandstones of the Taurides (N Gondwana margin). The main aim is to detect and quantify the contribution of Triassic magmatism as detritus to either of these crustal blocks. This follows the recent discovery of a Triassic magmatic arc source for the Triassic sandstones of the Palaeotethyan Karakaya subduction-accretion complex (Ustaömer et al. 2013; this meeting). Carboniferous (Variscan) zircon grains also form a significant detrital population, plus several more minor populations. Six sandstone samples were studied, two from the İstanbul Terrane (Bakırlıkıran Formation of the Kocaeli Triassic Basin) and four from the Tauride Autochthon (latest Triassic Üzümdere Formation and Mid-Triassic Kasımlar Formations; Beyşehir region). Detrital zircon grains were dated by the laser ablation-inductively coupled plasma-mass spectrometer (LA-ICP-MS) U-Pb method at Goethe University, Frankfurt. Our results do not reveal Triassic detritus in the Üzümdere Formation. The U-Pb age of the analysed zircon grains ranges from 267 Ma to 3.2 Ga. A small fraction of Palaeozoic zircons are Permian (267 to 296 Ma), whereas the remainder are Early Palaeozoic. Ordovician grains (4%) form two age clusters, one at ca. 450 Ma and the other at ca. 474 Ma. Cambrian-aged grains dominate the zircon population, while the second largest population is Ediacaran (576 to 642 Ma). Smaller populations occur at 909-997 Ma, 827-839 Ma, 1.8-2.0 Ga and 2.4-2.6 Ga. The sandstones of the Kasımlar Formation have similar zircon age cluster to those of the somewhat younger Üzümdere Formation, ranging from 239 Ma to 2.9 Ga. A few grains gave Anisian ages. Cambrian zircon grains are less pronounced than in the Kasımlar Formation compared to the Üzümdere Formation. The detrital zircon record of Tauride sandstones, therefore, not indicates significant contribution

  4. Digital Base Band Converter As Radar Vlbi Backend / Dbbc Kā Ciparošanas Sistēma Radara Vlbi Novērojumiem

    NASA Astrophysics Data System (ADS)

    Tuccari, G.; Bezrukovs, Vl.; Nechaeva, M.

    2012-12-01

    can then allow exploring easily the desired range of search for unknown or not fully determined orbit objects. These features make Radar VLBI personality most useful in the space debris measurements. DBBC sistēma izstrādāta Noto Radioastronomijas institūtā. Sistēmas galvenaisuzdevums - palielināt visa Eiropas VLBI tīkla jutību - realizēts, palielinotvisas novērojamās joslas platumu un pielietojot ciparu signālu apstrādes metodes.Izejas datu plūsma palielināta no 1 līdz 4 Gbps katram radioteleskopam un visasoperācijas, kas saistītas ar signālu apstrādi (frekvences pārveidošana, pastiprinājums,iekšējie ģeneratori, utt.), realizētas digitālā formā, kas ļauj iegūt nozīmīgusuzlabojumus atkārtojamībā, precizitātē, vienkāršībā, nemaz neminot vispārzināmāspriekšrocības, ko nodrošina digitālo tehnoloģiju izmantošana. Maksimālā ieejassignāla frekvenču josla ir 3.5 GHz, un momentānais joslas platums ir līdz 1 GHz uzkatru no astoņiem iespējamajiem RF/IF kanāliem. Šī datu reģistrācijas sistēma irļoti veiktspējīga platforma ne tikai EVN, bet arī citiem radioastronomijas pielietojumiem,un papildus tiek izstrādāta vesela virkne programmatūras pakotņu, kasvēl vairāk paplašina sistēmas funkcionalitāti. Tas ietver PFB (Polifāzes FiltruBanka) uztvērējus "Spectra”, kas piemēroti augstas izšķirtspējas spektroskopijasvajadzībām. Papildus realizēts jaunas programmatūras risinājums, ar mērķiizmantot DBBC sistēmu kā daudzfunkcionālu datu ciparošanas iekārtu, kasizmantojama bistatiskiem radara novērojumiem, tai skaitā arī radara VLBInovērojumiem. Šāda veida novērojumos tiek pētīta kosmisko atlūzu populācija,nodrošinot iespēju detektēt pat centimetra

  5. Res-E Support Policies in the Baltic States: Electricity Price Aspect (Part II)

    NASA Astrophysics Data System (ADS)

    Bobinaite, V.; Priedite, I.

    2015-04-01

    Increasing volumes of electricity derived from renewable energy sources (RES-E) affect the electricity market prices and the prices for final electricity consumers in the Baltic States. The results of a multivariate regression analysis show that in 2013 the RES-E contributed to decreasing the electricity market prices in the Baltic States. However, the final electricity consumers pay for the promotion of RES-E through the approved RES-E component which has a tendency to increase. It is estimated that in 2013 the net benefits from the wind electricity promotion were achieved in Lithuania and Latvia while the net cost - in Estonia. This suggests that the economic efficiency of the wind electricity support scheme based on the application of feed-in tariffs was higher than that based on the feed-in premium. Rakstā analizēta elektroenerģijas ražošanas no atjaunojamiem energoresursiem (AER-E) palielināšanas ietekme uz elektroenerģijas tirgus cenu un gala cenu elektroenerģijas lietotājiem Baltijas valstīs. Daudzfaktoru regresijas analīzes rezultāti atklāja, ka AER-E 2013. gadā varētu samazināt elektroenerģijas tirgus cenas Baltijas valstīs. Tomēr jāņem vērā, ka elektroenerģijas lietotāja gala cenā ir iekļauta AER-E atbalsta komponente, kurai ir raksturīgi palielināties. Aprēķināts, ka no vēja elektroenerģijas ražošanas Latvijā un Lietuvā tika iegūta tīrā peļņa, bet Igaunijā tikai nosedza pašizmaksu. Tas liecina, ka vēja elektroenerģijas atbalsta shēmai, kas balstīta uz obligātā iepirkuma atbalsta principu, ir augstāka ekonomiskā efektivitāte, nekā atbalsta shēmai, kas balstīta uz piemaksu par no AER saražoto elektroenerģiju obligātā iepirkuma ietvaros.

  6. Breeding response of transcript profiling in developing seeds of Brassica napus.

    PubMed

    Hu, Yaping; Wu, Gang; Cao, Yinglong; Wu, Yuhua; Xiao, Ling; Li, Xiaodan; Lu, Changming

    2009-05-24

    The upgrading of rapeseed cultivars has resulted in a substantial improvement in yield and quality in China over the past 30 years. With the selective pressure against fatty acid composition and oil content, high erucic acid- and low oil-content cultivars have been replaced by low erucic acid- and high oil-content cultivars. The high erucic acid cultivar Zhongyou 821 and its descendent, low erucic acid cultivar Zhongshuang 9, are representatives of two generations of the most outstanding Chinese rapeseed cultivars (B. napus) developed the past 2 decades. This paper compares the transcriptional profiles of Zhongshuang 9 and Zhongyou 821 for 32 genes that are principally involved in lipid biosynthesis during seed development in order to elucidate how the transcriptional profiles of these genes responded to quality improvement over the past 20 years. Comparison of the cultivar Zhongyou 821 with its descendent, Zhongshuang 9, shows that the transcriptional levels of seven of the 32 genes were upregulated by 30% to 109%, including FAD3, ACCase, FAE1, GKTP, Caleosin, GAPDH, and PEPC. Of the 32 genes, 10 (KAS3, beta-CT, BcRK6, P450, FatA, Oleosin, FAD6, FatB, alpha-CT and SUC1) were downregulated by at least 20% and most by 50%. The Napin gene alone accounted for over 75% of total transcription from all 32 genes assessed in both cultivars. Most of the genes showed significant correlation with fatty acid accumulation, but the correlation in ZS9 was significantly different from that in ZY821. Higher KCR2 activity is associated with higher C16:0, C18:0, and C18:2 in both cultivars, lower C22:1 and total fatty acid content in ZY821, and lower 18:1 in ZS9. This paper illustrates the response of the transcription levels of 32 genes to breeding in developing rapeseed seeds. Both cultivars showed similar transcription profiles, with the Napin gene predominantly transcribed. Selective pressure for zero erucic acid, low glucosinolate, high oleic acid and high oil content, as well

  7. Aluminum coordinations for aluminosilicate glasses at 1 atm. and 3GPa: a 27Al MAS NMR study

    NASA Astrophysics Data System (ADS)

    Allwardt, J. R.; Stebbins, J. F.; Withers, A. C.; Hirschmann, M. M.

    2003-12-01

    In this study, we used 27Al MAS NMR to investigate the distribution of different aluminum coordinations in ambient pressure and moderate pressure (3GPa) aluminosilicate glasses with compositions of Mx+(9-3x)Al2Si6O18, where M= Ca2+, Na+, and K+. These spectra were collected at 18.8 Tesla to minimize the peak broadening due to second-order quadrupolar effects, which causes overlapping peaks for different coordinations of Al. Aluminum is thought to be mostly tetrahedrally coordinated in ambient-pressure aluminosilicate glasses where M+(2-x)O >= Al2O3, but 27Al NMR studies have shown that small concentrations of high-coordinated Al are present in both charge balanced (Toplis et al. 2000; Stebbins et al. 2001) and "depolymerized" (M+(2-x)O > Al2O3) aluminosilicate glasses (Stebbins and Farnan 1992). The 27Al spectra of samples of this study show that these ambient pressure glasses all contain [5]Al. Interestingly, the NAS (Na-aluminosilicate) glass contains more [5]Al than the KAS glass (0.6 vs. 0.3, respectively), which is opposite of that observed for SiO[5] groups in binary silicate glasses (Stebbins and McMillan 1993). The CAS glass spectrum shows a shoulder at 25 ppm, but the [4]Al peak is too broad to assign a reliable percentage for the amount of [5]Al. Previous studies of high-pressure glasses have shown that Al transforms to higher coordinations with increasing pressures (Yarger et al. 1995). In this study, we observe that the 27Al MAS spectrum of the 3 GPa NAS glass shows that 7% [5]Al and 1% [6]Al species exist. Additionally, the spectra of the KAS glass shows that 2% [5]Al and possibly some [6]Al are present at 3 GPa. These spectra clearly show for the first time that pressure induced Al-coordination changes occur in aluminosilicate glasses at pressures of 3 GPa. Recent 27Al NMR spectra of high-pressure "depolymerized" aluminosilicate glasses with different fictive temperatures have shown that the amount of high-coordinated Al increases with increasing

  8. A promising approach for treatment of tumor-induced bone diseases: utilizing bisphosphonate derivatives of nucleoside antimetabolites.

    PubMed

    Reinholz, Monica M; Zinnen, Shawn P; Dueck, Amylou C; Dingli, David; Reinholz, Gregory G; Jonart, Leslie A; Kitzmann, Kathleen A; Bruzek, Amy K; Negron, Vivian; Abdalla, Abdalla K; Arendt, Bonnie K; Croatt, Anthony J; Sanchez-Perez, Luis; Sebesta, David P; Lönnberg, Harri; Yoneda, Toshiyuki; Nath, Karl A; Jelinek, Diane F; Russell, Stephen J; Ingle, James N; Spelsberg, Thomas C; Dixon, Henry B F Hal; Karpeisky, Alexander; Lingle, Wilma L

    2010-07-01

    Despite palliative treatments, tumor-induced bone disease (TIBD) remains highly debilitating for many cancer patients and progression typically results in death within two years. Therefore, more effective therapies with enhanced anti-resorptive and cytotoxic characteristics are needed. We developed bisphosphonate-chemotherapeutic conjugates designed to bind bone and hydrolyze, releasing both compounds, thereby targeting both osteoclasts and tumor cells. This study examined the effects of our lead compound, MBC-11 (the anhydride formed between arabinocytidine (AraC)-5'-phosphate and etidronate), on bone tumor burden, bone volume, femur bone mineral density (BMD), and overall survival using two distinct mouse models of TIBD, the 4T1/luc breast cancer and the KAS-6/1-MIP1alpha multiple myeloma models. In mice orthotopically inoculated with 4T1/luc mouse mammary cells, MBC-11 (0.04 microg/day; s.c.) reduced the incidence of bone metastases to 40% (4/10), compared to 90% (9/10; p=0.057) and 100% (5/5; p=0.04) of PBS- or similarly-dosed, zoledronate-treated mice, respectively. MBC-11 also significantly decreased bone tumor burden compared to PBS- or zoledronate-treated mice (p=0.021, p=0.017, respectively). MBC-11 and zoledronate (0.04 microg/day) significantly increased bone volume by two- and four-fold, respectively, compared to PBS-treated mice (p=0.005, p<0.001, respectively). In mice systemically injected with human multiple myeloma KAS-6/1-MIP1alpha cells, 0.04 and 4.0 microg/day MBC-11 improved femur BMD by 13% and 16%, respectively, compared to PBS (p=0.025, p=0.017, respectively) at 10 weeks post-tumor cell injection and increased mean survival to 95 days compared to 77 days in mice treated with PBS (p=0.047). Similar doses of zoledronate also improved femur BMD (p< or =0.01 vs PBS) and increased mean survival to 86 days, but this was not significantly different than in PBS-treated mice (p=0.53). These results demonstrate that MBC-11 decreases bone tumor burden

  9. Breeding response of transcript profiling in developing seeds of Brassica napus

    PubMed Central

    Hu, Yaping; Wu, Gang; Cao, Yinglong; Wu, Yuhua; Xiao, Ling; Li, Xiaodan; Lu, Changming

    2009-01-01

    Background The upgrading of rapeseed cultivars has resulted in a substantial improvement in yield and quality in China over the past 30 years. With the selective pressure against fatty acid composition and oil content, high erucic acid- and low oil-content cultivars have been replaced by low erucic acid- and high oil-content cultivars. The high erucic acid cultivar Zhongyou 821 and its descendent, low erucic acid cultivar Zhongshuang 9, are representatives of two generations of the most outstanding Chinese rapeseed cultivars (B. napus) developed the past 2 decades. This paper compares the transcriptional profiles of Zhongshuang 9 and Zhongyou 821 for 32 genes that are principally involved in lipid biosynthesis during seed development in order to elucidate how the transcriptional profiles of these genes responded to quality improvement over the past 20 years. Results Comparison of the cultivar Zhongyou 821 with its descendent, Zhongshuang 9, shows that the transcriptional levels of seven of the 32 genes were upregulated by 30% to 109%, including FAD3, ACCase, FAE1, GKTP, Caleosin, GAPDH, and PEPC. Of the 32 genes, 10 (KAS3, β-CT, BcRK6, P450, FatA, Oleosin, FAD6, FatB, α-CT and SUC1) were downregulated by at least 20% and most by 50%. The Napin gene alone accounted for over 75% of total transcription from all 32 genes assessed in both cultivars. Most of the genes showed significant correlation with fatty acid accumulation, but the correlation in ZS9 was significantly different from that in ZY821. Higher KCR2 activity is associated with higher C16:0, C18:0, and C18:2 in both cultivars, lower C22:1 and total fatty acid content in ZY821, and lower 18:1 in ZS9. Conclusion This paper illustrates the response of the transcription levels of 32 genes to breeding in developing rapeseed seeds. Both cultivars showed similar transcription profiles, with the Napin gene predominantly transcribed. Selective pressure for zero erucic acid, low glucosinolate, high oleic acid and

  10. The impact of medical tourism on colorectal screening among Korean Americans: A community-based cross-sectional study.

    PubMed

    Ko, Linda K; Taylor, Victoria M; Yoon, Jihye; Copeland, Wade K; Hwang, Joo Ha; Lee, Eun Jeong; Inadomi, John

    2016-12-01

    Colorectal cancer (CRC) remains the most commonly diagnosed cancer among Korean Americans (KAs) in part due to low screening rates. Recent studies suggest that some KA patients engage in medical tourism and receive medical care in their home country. The impact of medical tourism on CRC screening is unknown. The purpose of this paper was to 1) investigate the frequency of medical tourism, 2) examine the association between medical tourism and CRC screening, and 3) characterize KA patients who engage in medical tourism. This is a community-based, cross-sectional study involving self-administered questionnaires conducted from August 2013 to October 2013. Data was collected on 193 KA patients, ages 50-75, residing in the Seattle metropolitan area. The outcome variable is up-to-date with CRC screening, defined as having had a stool test (Fecal Occult Blood Test or Fecal Immunochemical Test) within the past year or a colonoscopy within 10 years. Predictor variables are socio-demographics, health factors, acculturation, knowledge, financial concerns for medical care costs, and medical tourism. In multi-variate modeling, medical tourism was significantly related to being up-to-date with CRC screening. Participants who engaged in medical tourism had 8.91 (95% CI: 3.89-23.89) greater odds of being up-to-date with CRC screening compared to those who did not travel for healthcare. Factors associated with engaging in medical tourism were lack of insurance coverage (P = 0.008), higher levels of education (P = 0.003), not having a usual place of care (P = 0.002), older age at immigration (P = 0.009), shorter years-of-stay in the US (P = 0.003), and being less likely to speak English well (P = 0.03). This study identifies the impact of medical tourism on CRC screening and characteristics of KA patients who report engaging in medical tourism. Healthcare providers in the US should be aware of the customary nature of medical tourism among KAs and consider

  11. Expression Quantitative Trait Locus Mapping across Water Availability Environments Reveals Contrasting Associations with Genomic Features in Arabidopsis[C][W][OPEN

    PubMed Central

    Lowry, David B.; Logan, Tierney L.; Santuari, Luca; Hardtke, Christian S.; Richards, James H.; DeRose-Wilson, Leah J.; McKay, John K.; Sen, Saunak; Juenger, Thomas E.

    2013-01-01

    The regulation of gene expression is crucial for an organism’s development and response to stress, and an understanding of the evolution of gene expression is of fundamental importance to basic and applied biology. To improve this understanding, we conducted expression quantitative trait locus (eQTL) mapping in the Tsu-1 (Tsushima, Japan) × Kas-1 (Kashmir, India) recombinant inbred line population of Arabidopsis thaliana across soil drying treatments. We then used genome resequencing data to evaluate whether genomic features (promoter polymorphism, recombination rate, gene length, and gene density) are associated with genes responding to the environment (E) or with genes with genetic variation (G) in gene expression in the form of eQTLs. We identified thousands of genes that responded to soil drying and hundreds of main-effect eQTLs. However, we identified very few statistically significant eQTLs that interacted with the soil drying treatment (GxE eQTL). Analysis of genome resequencing data revealed associations of several genomic features with G and E genes. In general, E genes had lower promoter diversity and local recombination rates. By contrast, genes with eQTLs (G) had significantly greater promoter diversity and were located in genomic regions with higher recombination. These results suggest that genomic architecture may play an important a role in the evolution of gene expression. PMID:24045022

  12. Potent, selective, and orally efficacious antagonists of melanin-concentrating hormone receptor 1.

    PubMed

    Tavares, Francis X; Al-Barazanji, Kamal A; Bigham, Eric C; Bishop, Michael J; Britt, Christy S; Carlton, David L; Feldman, Paul L; Goetz, Aaron S; Grizzle, Mary K; Guo, Yu C; Handlon, Anthony L; Hertzog, Donald L; Ignar, Diane M; Lang, Daniel G; Ott, Ronda J; Peat, Andrew J; Zhou, Hui-Qiang

    2006-11-30

    The high expression of MCH in the hypothalamus with the lean hypophagic phenotype coupled with increased resting metabolic rate and resistance to high fat diet-induced obesity of MCH KO mice has spurred considerable efforts to develop small molecule MCHR1 antagonists. Starting from a lead thienopyrimidinone series, structure-activity studies at the 3- and 6-positions of the thienopyrimidinone core afforded potent and selective MCHR1 antagonists with representative examples having suitable pharmacokinetic properties. Based on structure-activity relationships, a structural model for MCHR1 was constructed to explain the binding mode of these antagonists. In general, a good correlation was observed between pKas and activity in the right-hand side of the template, with Asp123 playing an important role in the enhancement of binding affinity. A representative example when evaluated chronically in diet-induced obese mice resulted in good weight loss effects. These antagonists provide a viable lead series in the discovery of new therapies for the treatment of obesity.

  13. Exploiting Differential Gene Expression and Epistasis to Discover Candidate Genes for Drought-Associated QTLs in Arabidopsis thaliana.

    PubMed

    Lovell, John T; Mullen, Jack L; Lowry, David B; Awole, Kedija; Richards, James H; Sen, Saunak; Verslues, Paul E; Juenger, Thomas E; McKay, John K

    2015-04-01

    Soil water availability represents one of the most important selective agents for plants in nature and the single greatest abiotic determinant of agricultural productivity, yet the genetic bases of drought acclimation responses remain poorly understood. Here, we developed a systems-genetic approach to characterize quantitative trait loci (QTLs), physiological traits and genes that affect responses to soil moisture deficit in the TSUxKAS mapping population of Arabidopsis thaliana. To determine the effects of candidate genes underlying QTLs, we analyzed gene expression as a covariate within the QTL model in an effort to mechanistically link markers, RNA expression, and the phenotype. This strategy produced ranked lists of candidate genes for several drought-associated traits, including water use efficiency, growth, abscisic acid concentration (ABA), and proline concentration. As a proof of concept, we recovered known causal loci for several QTLs. For other traits, including ABA, we identified novel loci not previously associated with drought. Furthermore, we documented natural variation at two key steps in proline metabolism and demonstrated that the mitochondrial genome differentially affects genomic QTLs to influence proline accumulation. These findings demonstrate that linking genome, transcriptome, and phenotype data holds great promise to extend the utility of genetic mapping, even when QTL effects are modest or complex. © 2015 American Society of Plant Biologists. All rights reserved.

  14. The Competing Mechanisms of Phosphate Monoester Dianion Hydrolysis

    PubMed Central

    2016-01-01

    Despite the numerous experimental and theoretical studies on phosphate monoester hydrolysis, significant questions remain concerning the mechanistic details of these biologically critical reactions. In the present work we construct a linear free energy relationship for phosphate monoester hydrolysis to explore the effect of modulating leaving group pKa on the competition between solvent- and substrate-assisted pathways for the hydrolysis of these compounds. Through detailed comparative electronic-structure studies of methyl phosphate and a series of substituted aryl phosphate monoesters, we demonstrate that the preferred mechanism is dependent on the nature of the leaving group. For good leaving groups, a strong preference is observed for a more dissociative solvent-assisted pathway. However, the energy difference between the two pathways gradually reduces as the leaving group pKa increases and creates mechanistic ambiguity for reactions involving relatively poor alkoxy leaving groups. Our calculations show that the transition-state structures vary smoothly across the range of pKas studied and that the pathways remain discrete mechanistic alternatives. Therefore, while not impossible, a biological catalyst would have to surmount a significantly higher activation barrier to facilitate a substrate-assisted pathway than for the solvent-assisted pathway when phosphate is bonded to good leaving groups. For poor leaving groups, this intrinsic preference disappears. PMID:27471914

  15. Specificity of binding of beta-glucoside activators of ryegrass (1-->3)-beta-glucan synthase and the synthesis of some potential photoaffinity activators.

    PubMed Central

    Ng, K; Johnson, E; Stone, B A

    1996-01-01

    Structure-activity relationships among glycoside activators of ryegrass (Lolium multiflorum) (1-->3)-beta-glucan synthase were investigated using a number of natural and synthetic glycosides, including some carrying photoaffinity functions. There is an absolute requirement for a beta-D-glycosyl moiety in the activator, both S- and N-glucosides are active, and the position of the glucosidic linkage in beta-glucose disaccharides has a significant effect on the affinity of binding. However, the binding requirement does not extend beyond a single beta-D-glucosyl residue, and beta-D-oligoglucosides are less effective than disaccharides. The nature of the aglycon has a major influence on the binding affinity. Hydrophobic aglycons lower the concentration required for half-maximal stimulation of the enzyme obtained from an Eadie-Hofstee plot of kinetic data (Ka) for activation, but charge aglycons increase Ka. Relative to methyl-beta-D-glucoside and cellobiose (Ka 1.1 mM), the most potent compounds tested were N-[4-(benzoyl)benzoyl]-beta-D-glucosylamine and 2'-[4-azidosalicylamino]ethyl-1-thio-beta-D-glucoside with K(a)s of approximately 30 microM. The latter also was tested for its potential to specifically label the beta-glucoside-binding site on the synthase, but under the conditions used the binding was found to be nonspecific. PMID:8756503

  16. Kinetics of the initial steps in the aqueous oxidation of thiosulfate by chlorine dioxide.

    PubMed

    Pan, Changwei; Stanbury, David M

    2014-08-28

    The reaction of ClO2(•) with S2O3(2-) in aqueous solution is a component of the "crazy clock" reaction of ClO2(-) with S2O3(2-), and under conditions of excess S2O3(2-) the absorbance at 360 nm due to ClO2(•) decays with sigmoidal kinetics. A chain reaction mechanism is inferred on the basis that very small concentrations of SO3(2-) accelerate the reaction, and methionine inhibits the reaction. Pseudo-first-order kinetics is observed in the presence of relatively large methionine concentrations, leading to the simple rate law -d[ClO2]/dt = (ka[S2O3(2-)] + kb[S2O3(2-)](2))[ClO2], with ka = 452 ± 16 M(-1) s(-1) and kb = (5.7 ± 0.2) × 10(5) M(-2) s(-1) at 25 °C and pH 7.6. Under these conditions, the initial products are ClO2(-) and S4O6(2-). A classical electron-transfer mechanism is assigned to the reaction that occurs under conditions of methionine inhibition.

  17. Extending the Study of the 6,8 Rearrangement in Flavylium Compounds to Higher pH Values: Interconversion between 6-Bromo and 8-Bromo-apigeninidin.

    PubMed

    Cruz, Luís M; Basílio, Nuno M; de Freitas, Victor A; Lima, João C; Pina, Fernando J

    2016-06-01

    The rearrangement between isomers 6- and 8-bromo-apigeninidin (6 and 8) was studied by pH jumps using stopped flow, UV/Vis, NMR, and HPLC analysis. The system constitutes a pH-dependent network of chemical reactions involving up to 18 different species. The dynamic network is equivalent to a single diprotic acid exhibiting two pKas, 2.55 and 5.4. Similar to other flavylium derivatives, the mole fraction of the species hemiketal and cis-chalcone in both multistate isomers are negligible at the equilibrium. At pH 1, the pure isomers are slowly converted in a mixture containing about 50 % of isomers 6 and 8, while at pH 4, the system evolves to mixture of 10 % trans-chalcone and 90 % of quinoidal bases. A series of pH jumps from pure isomer 6 at pH 1 to pH 6 and back to pH 1 leads to the same initial absorption spectra of the pure isomer 6. The same occurs for pure isomer 8, showing the lack of communication between the cis-chalcones, at least in the time scale of few minutes. A pH jump from the equilibrated mixture of the isomers at pH 1.0 to 5.8 permits to follow a very slow isomerization.

  18. Hiding and unveiling trans-chalcone in a constrained derivative of 4',7-dihydroxyflavylium in water: a versatile photochromic system.

    PubMed

    Pessêgo, Márcia; Gago, Sandra; Basílio, Nuno; Laia, César A T; Jorge Parola, A; Lima, João C; Pina, Fernando

    2017-01-04

    A structurally constrained derivative of 4',7-dihydroxyflavylium was studied in aqueous solution and in CTAB micelles by pH jumps, flash photolysis and continuous irradiation with spectroscopic details assessed as well by theoretical calculations. In water, up to pH = 8, the compound shows only acid base chemistry with deprotonation of the flavylium cation to form a quinoidal base that further deprotonates with pKas of 4.8 and 7.4. In the basic region, unprotonated trans-chalcones are formed. No neutral trans-chalcone (Ct) is formed in water preventing the establishment of the well-known photochromism involving photoisomerization of this species with subsequent formation of the flavylium cation. Addition of 0.02 M CTAB drastically changes the mole fraction distribution of species, leading to the formation of Ct (χCt = 1 at pH = 5) and unveiling a photochromic behavior with a pH-tunable colour contrast in a large pH range (2 < pH < 8). The Ct species can be hidden again (irreversibly) upon addition of α-cyclodextrin that disrupts the CTAB micelles, reverting the system to its initial mole fraction distribution of species. These supramolecular inputs work atop the molecular reaction networks by modifying their species' mole fraction distribution.

  19. Glycine Enolates: The Effect of Formation of Iminium Ions to Simple Ketones on α-Amino Carbon Acidity and a Comparison with Pyridoxal Iminium Ions

    PubMed Central

    Crugeiras, Juan; Rios, Ana; Riveiros, Enrique; Amyes, Tina L.; Richard, John P.

    2009-01-01

    Equilibrium constants in D2O were determined by 1H-NMR analyses for formation of imines/iminium ions from addition of glycine methyl ester to acetone and from addition of glycine to phenylglyoxylate. First-order rate constants, also determined by 1H NMR, are reported for deuterium exchange between solvent D2O and the α–amino carbon of glycine methyl ester and glycine in the presence of increasing concentrations of ketone and Brønsted bases. These rate and equilibrium data were used to calculate second-order rate constants for deprotonation by DO− and by Brønsted bases of the α-imino carbon of the ketone adducts. Formation of the iminium ion between acetone and glycine methyl ester and between phenylglyoxylate and glycine is estimated to cause 7 unit and 16 unit decreases, respectively, in the pKas of 21 and 29 for deprotonation of the parent carbon acids. The effect of formation of iminium ions to phenylglyoxylate and to 5′-deoxypyridoxal (DPL) [Toth, K.; Richard, J. P. J. Am. Chem. Soc. 2007, 129, 3013–3021] on the carbon acidity of glycine is similar. However, DPL is a much better catalyst than phenylglyoxylate of deprotonation of glycine, because of the exceptionally large thermodynamic driving force for conversion of the amino acid and DPL to the reactive iminium ion. PMID:18198876

  20. Bohr effect of human hemoglobin: Separation of tertiary and quaternary contributions based on the Wyman equation.

    PubMed

    Okonjo, Kehinde Onwochei

    2017-09-01

    As a prelude to separating tertiary from quaternary structure contributions to the Bohr effect, we employed the Wyman equation to analyze Bohr data for human hemoglobin to which 2,3-bisphosphoglycerate, 2,3-BPG, is bound. Changes in the pKas of the histidine Bohr groups result in a net reduction of their contributions to the Bohr effect at pH 7.4 compared to their contributions in stripped hemoglobin. The non-histidine 2,3-BPG binding groups - the β-chain terminal amino group and Lys82β - make negative and positive contributions, respectively, to the Bohr effect. The final result is that the Bohr effect at physiological pH is higher for 2,3-BPG bound compared to stripped hemoglobin. Contributions linked to His2β, His77β and His143β enable us to separate tertiary from quaternary Bohr contributions in stripped and in 2,3-BPG bound hemoglobin. Both contributions serve to make the Bohr effect for 2,3-BPG bound hemoglobin higher than for stripped hemoglobin at physiological pH. Copyright © 2017 Elsevier B.V. All rights reserved.

  1. COMPASS Final Report: Lunar Relay Satellite (LRS)

    NASA Technical Reports Server (NTRS)

    Oleson, Steven R.; McGuire, Melissa L.

    2012-01-01

    The Lunar Relay Satellite (LRS) COllaborative Modeling and Parametric Assessment of Space Systems (COMPASS) session was tasked to design a satellite to orbit in an elliptical lunar polar orbit to provide relay communications between lunar South Pole assets and the Earth. The design included a complete master equipment list, power requirement list, configuration design, and brief risk assessment and cost analysis. The LRS is a half-TDRSS sized box spacecraft, which provides communications and navigation relay between lunar outposts (via Lunar Communications Terminals (LCT)) or Sortie parties (with user radios) and large ground antennas on Earth. The LRS consists of a spacecraft containing all the communications and avionics equipment designed by NASA Jet Propulsion Laboratory s (JPL) Team X to perform the relay between lunar-based assets and the Earth. The satellite design is a standard box truss spacecraft design with a thermal control system, 1.7 m solar arrays for 1 kWe power, a 1 m diameter Ka/S band dish which provides relay communications with the LCT, and a Q-band dish for communications to/from the Earth based assets. While JPL's Team X and Goddard Space Flight Center s (GSFC) I M Design Center (IMDC) have completed two other LRS designs, this NASA Glenn Research Center (GRC) COMPASS LRS design sits between them in terms of physical size and capabilities.

  2. Genome scale transcriptional response diversity among ten ecotypes of Arabidopsis thaliana during heat stress

    PubMed Central

    Barah, Pankaj; Jayavelu, Naresh D.; Mundy, John; Bones, Atle M.

    2013-01-01

    In the scenario of global warming and climate change, heat stress is a serious threat to crop production worldwide. Being sessile, plants cannot escape from heat. Plants have developed various adaptive mechanisms to survive heat stress. Several studies have focused on diversity of heat tolerance levels in divergent Arabidopsis thaliana (A. thaliana) ecotypes, but comprehensive genome scale understanding of heat stress response in plants is still lacking. Here we report the genome scale transcript responses to heat stress of 10 A. thaliana ecotypes (Col, Ler, C24, Cvi, Kas1, An1, Sha, Kyo2, Eri, and Kond) originated from different geographical locations. During the experiment, A. thaliana plants were subjected to heat stress (38°C) and transcript responses were monitored using Arabidopsis NimbleGen ATH6 microarrays. The responses of A. thaliana ecotypes exhibited considerable variation in the transcript abundance levels. In total, 3644 transcripts were significantly heat regulated (p < 0.01) in the 10 ecotypes, including 244 transcription factors and 203 transposable elements. By employing a systems genetics approach- Network Component Analysis (NCA), we have constructed an in silico transcript regulatory network model for 35 heat responsive transcription factors during cellular responses to heat stress in A. thaliana. The computed activities of the 35 transcription factors showed ecotype specific responses to the heat treatment. PMID:24409190

  3. Use of STOP Bang Questionnaire in Outpatient Setting: Increasing Both Identification of Obstructive Sleep Apnea Patients and Polysomnography Referral Accuracy

    DTIC Science & Technology

    2017-05-16

    niqulred to pUbUCl’L(pr~ yoar rllilfMl11Jr; . tt :tou n:r1e a:n’). quesUOJ’ls or CQrCCJn~ i;4~~ cx:nm a lte 59 CROtPlbltc11rccfls ar:o PreV-r.t...bt.cM:llnlprcser’liltk:o, a ne.· 59 Pn::1-ll Farm ~1!39 mzl be subm~ 1or rc...-..ev.• and .:t~L ·a. tt fl!Ur m11rr.Jsa\\X 15’ a«eple-d 1or santnc pc.tl~n. p"kas:e...8217 Al’lilnA.l9 llfld tt 󈧎 Ar:Wnal Woffaro Acl Of fillS(i, as Al11Ql’ldod.. 59 MOW FORM 3039. 20160628 f’r=tllted 11Y 59 M0\\\\1 0-108 PREVIOUS EDITIONS ARE

  4. Substituent Effects on the Thermodynamic Stability of Imines Formed from Glycine and Aromatic Aldehydes: Implications for the Catalytic Activity of Pyridoxal-5'-Phosphate (PLP)

    PubMed Central

    Crugeiras, Juan; Rios, Ana; Riveiros, Enrique; Richard, John P.

    2009-01-01

    Equilibrium constants for addition of glycine to substituted benzaldehydes to form the corresponding imines and pKas for ionization of the iminium ions were determined by 1H NMR analysis in D2O. The introduction of a phenoxide anion substituent into the aromatic ring of benzaldehyde leads to a substantial increase in the pKa of the iminium ion from 6.3 to 10.2 for p-hydroxybenzaldehyde and to 12.1 for salicyaldehyde. An analysis of the differential effect of ortho- versus para-substitution shows that the iminium ion to salicylaldehyde is stabilized by an intramolecular hydrogen bond in aqueous solution, with an estimated energy ca. 3 kcal/mol larger than can be accounted for by a simple electrostatic interaction. A comparison of the o-O− substituent effect on the acidity of the iminium ions of glycine to benzaldehyde and 4-pyridine-carboxaldehyde provides evidence for the existence of an internal hydrogen bond of similar strength in pyridoxal 5'-phosphate (PLP) iminium ions in water. The effects of other ring substituents on the stability of PLP iminium ions are discussed. PMID:19807092

  5. Kinetic analysis of manure pyrolysis and combustion processes.

    PubMed

    Fernandez-Lopez, M; Pedrosa-Castro, G J; Valverde, J L; Sanchez-Silva, L

    2016-12-01

    Due to the depletion of fossil fuel reserves and the environmental issues derived from their use, biomass seems to be an excellent source of renewable energy. In this work, the kinetics of the pyrolysis and combustion of three different biomass waste samples (two dairy manure samples before (Pre) and after (Dig R) anaerobic digestion and one swine manure sample (SW)) was studied by means of thermogravimetric analysis. In this work, three iso-conversional methods (Friedman, Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS)) were compared with the Coats-Redfern method. The Ea values of devolatilization stages were in the range of 152-170kJ/mol, 148-178kJ/mol and 156-209kJ/mol for samples Pre, Dig R and SW, respectively. Concerning combustion process, char oxidation stages showed lower Ea values than that obtained for the combustion devolatilization stage, being in the range of 140-175kJ/mol, 178-199kJ/mol and 122-144kJ/mol for samples Pre, Dig R and SW, respectively. These results were practically the same for samples Pre and Dig R, which means that the kinetics of the thermochemical processes were not affected by anaerobic digestion. Finally, the distributed activation energy model (DAEM) and the pseudo-multi component stage model (PMSM) were applied to predict the weight loss curves of pyrolysis and combustion. DAEM was the best model that fitted the experimental data.

  6. TRANSFORMERLESS OPERATION OF DIII-D WITH HIGH BOOTSTRAP FRACTION

    SciTech Connect

    POLITZER,PA; HYATT,AW; LUCE,TC; MAHDAVI,MA; MURAKAMI,M; PERKINS,FW; PRATER,R; TURNBULL,AD; CASPER,TA; FERRON,JR; JAYAKUMAR,RJ; LAHAYE,RJ; LAZARUS,EA; PETTY,CC; WADE,MR

    2003-07-01

    OAK-B135 The authors have initiated an experimental program to address some of the questions associated with operation of a tokamak with high bootstrap current fraction under high performance conditions, without assistance from a transformer. In these discharges they have maintained stationary (or slowly improving) conditions for > 2.2 s at {beta}{sub N} {approx} {beta}{sub p} {approx} 2.8. Significant current overdrive, with dI/dt > 50 kA/s and zero or negative voltage, is sustained for over 0.7 s. The overdrive condition is usually ended with the appearance of MHD activity, which alters the profiles and reduces the bootstrap current. Characteristically these plasmas have 65%-80% bootstrap current, 25%-30% NBCD, and 5%-10% ECCD. Fully noninductive operation is essential for steady-state tokamaks. For efficient operation, the bootstrap current fraction must be close to 100%, allowing for a small additional ({approx} 10%) external current drive capability to be used for control. In such plasmas the current and pressure profiles are rightly coupled because J(r) is entirely determined by p(r) (or more accurately by the kinetic profiles). The pressure gradient in turn is determined by transport coefficients which depend on the poloidal field profile.

  7. Comparative studies of the pyrolytic and kinetic characteristics of maize straw and the seaweed Ulva pertusa.

    PubMed

    Ye, Naihao; Li, Demao; Chen, Limei; Zhang, Xiaowen; Xu, Dong

    2010-09-10

    Seaweed has attracted considerable attention as a potential biofuel feedstock. The pyrolytic and kinetic characteristics of maize straw and the seaweed Ulva pertusa were studied and compared using heating rates of 10, 30 and 50°C min(-1) under an inert atmosphere. The activation energy, and pre-exponential factors were calculated by the Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Popescu methods. The kinetic mechanism was deduced by the Popescu method. The results indicate that there are three stages to the pyrolysis; dehydration, primary devolatilization and residual decomposition. There were significant differences in average activation energy, thermal stability, final residuals and reaction rates between the two materials. The primary devolatilization stage of U. pertusa can be described by the Avramic-Erofeev equation (n=3), whereas that of maize straw can be described by the Mampel Power Law (n=2). The average activation energy of maize straw and U. pertusa were 153.0 and 148.7 KJ mol(-1), respectively. The pyrolysis process of U.pertusa would be easier than maize straw. And co-firing of the two biomass may be require less external heat input and improve process stability. There were minor kinetic compensation effects between the pre-exponential factors and the activation energy.

  8. Effect of Bronsted Acids and Bases, and Lewis Acid (Sn(2+)) on the Regiochemistry of the Reaction of Amines with Trifluoromethyl-β-diketones: Reaction of 3-Aminopyrrole to Selectively Produce Regioisomeric 1H-Pyrrolo[3,2-b]pyridines.

    PubMed

    De Rosa, Michael; Arnold, David; Hartline, Douglas; Truong, Linda; Verner, Roman; Wang, Tianwei; Westin, Christian

    2015-12-18

    Reaction of 3-aminopyrrole (as its salt) with trifluoromethyl-β-diketones gave γ-1H-pyrrolo[3,2-b]pyridines via reaction at the less reactive carbonyl group. The trifluoromethyl group increased the electrophilicity of the adjacent carbonyl group and decreased the basicity of the hydroxyl group of the CF3 amino alcohol formed. This amino alcohol was formed faster, but its subsequent dehydration to the β-enaminone was slow resulting in the preferential formation of the γ-regioisomer. Reaction of 4,4,4-trifluoro-1-phenyl-1,3-butadione with 3-aminopyrrole was carried out using a series of 6 amine buffers. Yields of the α-1H-pyrrolo[3,2-b]pyridine increased as the pKa of the amine buffer decreased. Surprisingly the yield went down at higher pKas. There was a change in mechanism as the reaction mixture became more basic. With strong amines trifluoromethyl-β-diketones were present mainly or completely as the enolate. Under reductive conditions (3-nitropyrrole/Sn/AcOH/trifluoromethyl-β-diketone) the α-1H-pyrrolo[3,2-b]pyridine was the major product as a result of Lewis acid catalysis by Sn(2+). Similar α-regiochemistry was observed when the reaction of the 3-aminopyrrole salt with trifluoromethyl-β-diketones was carried out in the presence of base and tin(II) acetate.

  9. Expression quantitative trait locus mapping across water availability environments reveals contrasting associations with genomic features in Arabidopsis.

    PubMed

    Lowry, David B; Logan, Tierney L; Santuari, Luca; Hardtke, Christian S; Richards, James H; DeRose-Wilson, Leah J; McKay, John K; Sen, Saunak; Juenger, Thomas E

    2013-09-01

    The regulation of gene expression is crucial for an organism's development and response to stress, and an understanding of the evolution of gene expression is of fundamental importance to basic and applied biology. To improve this understanding, we conducted expression quantitative trait locus (eQTL) mapping in the Tsu-1 (Tsushima, Japan) × Kas-1 (Kashmir, India) recombinant inbred line population of Arabidopsis thaliana across soil drying treatments. We then used genome resequencing data to evaluate whether genomic features (promoter polymorphism, recombination rate, gene length, and gene density) are associated with genes responding to the environment (E) or with genes with genetic variation (G) in gene expression in the form of eQTLs. We identified thousands of genes that responded to soil drying and hundreds of main-effect eQTLs. However, we identified very few statistically significant eQTLs that interacted with the soil drying treatment (GxE eQTL). Analysis of genome resequencing data revealed associations of several genomic features with G and E genes. In general, E genes had lower promoter diversity and local recombination rates. By contrast, genes with eQTLs (G) had significantly greater promoter diversity and were located in genomic regions with higher recombination. These results suggest that genomic architecture may play an important a role in the evolution of gene expression.

  10. The interaction of beta-amyloid protein fragment (12-28) with lipid environments.

    PubMed Central

    Fletcher, T. G.; Keire, D. A.

    1997-01-01

    The neurotoxicity of beta-amyloid protein (beta AP) fragments may be a result of their solution conformation, which is very sensitive to solution conditions. In this work we describe NMR and CD studies of the conformation of beta AP(12-28) in lipid (micelle) environments as a function of pH and lipid type. The interaction of beta AP(12-28) with zwitterionic dodecylphosphocholine (DPC) micelles is weak and alters the conformation when compared to water solution alone. By contrast, the interaction of the peptide with anionic sodium dodecylsulfate (SDS) micelles is strong: beta AP(12-28) is mostly bound, is alpha-helical from K16 to V24, and aggregates slowly. The pH-dependent conformation changes of beta AP(12-28) in solution occur in the pH range at which the side-chain groups of E22, D23, H13, and H14 are deprotonated (pKas ca. 4 and 6.5); the interaction of beta AP(12-28) with SDS micelles alters the pH-dependent conformational transitions of the peptide whereas the weak interaction with DPC micelles causes little change. PMID:9070449

  11. BSE/GW calculations of liquid and solid H2O

    NASA Astrophysics Data System (ADS)

    Vinson, John; Kas, J. J.; Vila, F. D.; Rehr, J. J.; Shirley, E. L.

    2012-02-01

    We have calculated both the UV/VIS and Oxygen K-edge x-ray spectra of model ice and water systems within many-body perturbation theory using state-of-the-art Bethe-Salpeter equation (BSE) and GW self-energy approximations [1], as implemented in the valence- and core-excitation codes OCEAN and AI2NBSE [2]. While the various phases of crystalline ice have well-characterized structures, the local environment and fluctuations of liquid water remain subjects of debate. Due in part to limitations of previous theoretical models, the interpretation of experimental probes has been controversial. We find that the BSE approach, which provides an accurate treatment of core-hole interactions, is vital for a quantitative agreement between experiment and theory. Likewise the effects of self-energy corrections within the GW approximation are needed to explain the observed band-stretching and damping of the spectra. Prospects for further improvements are briefly discussed. [4pt] [1] J. Vinson, J. J. Kas, F. D. Vila, J. J. Rehr, and E. L. Shirley, arXiv:1010.0025 (2011).[0pt] [2] J. Vinson et al., Phys. Rev. B 83, 115106 (2011); H. M. Lawler et al., Phys. Rev. B 78, 205108 (2008).

  12. Thermal properties and optimization of process parameters for the growth of silver thiogallate crystal by differential scanning calorimetry

    NASA Astrophysics Data System (ADS)

    He, Zhiyu; Zhao, Beijun; Zhu, Shifu; Chen, Baojun; Huang, Wei

    2014-09-01

    In present work, thermal properties of silver thiogallate (AgGaS2) crystal were investigated by means of differential scanning calorimetry (DSC) measurements performed at different heating and cooling rates. The DSC results confirmed that the melting point was 1249 K with a slight change around 5 K and that the nucleation temperature varied from 1183 K to 1218 K. The supercooling temperature was evaluated in the range 37.69 K to 62.46 K which was considered to be harmful for the single nucleus formation at the beginning of crystal growth. The activation energy E and the pre-exponential factor A were also calculated using different isoconversional methods, namely Kissinger-Akahira-Sunose (KAS) method and Flynn-Wall-Ozawa (FWO) method, and the results showed good agreement with each other. According to the results of DSC, a larger temperature gradient up to 30 K/cm was utilized to suppress the formation and growth of multi nuclei and a rapid cooling rate 25 K/min was applied to minimize the second-phase precipitates during the process of crystal growth. Finally, an integral and transparent AgGaS2 single crystal with diameter of 22 mm and the length of 55 mm was obtained.

  13. Iso-conversional analysis of glass transition and crystallization in as-synthesis high yield of glassy Se98Cd2 nanorods

    NASA Astrophysics Data System (ADS)

    Dohare, C.; Mehta, N.

    2013-08-01

    In the present work, we have prepared high yield of glassy Se98Cd2 nanorods using melt-quench technique. The morphology and micro-structural analysis of as-prepared nanorods are characterized by SEM, XRD and EDX techniques. The glass transition and crystallization kinetics of glassy Se98Cd2 nanorods are studied at different heating rates (5, 10, 15, 20 K/min) using differential scanning calorimetric (DSC) technique. Four iso-conversional methods [Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), Tang and Straink] were used to determine the various kinetic parameters (crystallization temperature T αc, transition temperature T αg, activation energy of crystallization E αc, activation energy of glass transition E αg, order parameter n) of glass transition and crystallization process in non-isothermal mode. The monotonous decrease in activation energy E α with the crystallization fraction α confirm the complex kinetic mechanism of the glassy Se98Cd2 nanorods.

  14. Thermochemical conversion pathways of Kappaphycus alvarezii granules through study of kinetic models.

    PubMed

    Das, Prasanta; Mondal, Dibyendu; Maiti, Subarna

    2017-03-10

    Kappaphycus alvarezii seaweed belongs to the class of red alga (Rhodophyta). The granules obtained after recovery of "sap" (liquid plant stimulant) from freshly harvested alga is a promising biomass feedstock for energy application. Herein we report the kinetic behaviour of the granules using thermogravimetric analysis (TGA) at different heating rates in N2 atmosphere and thermogravimetric-mass spectrometry (TG-MS) analysis. Sawdust as lignocellulosic biomass is considered for comparative study. Four different kinetic models (i) multilinear regression technique, (ii) Friedman method, (iii) Flynn-Wall-Ozawa (FWO) method and (iv) Kissinger-Akahira-Sunose (KAS) method are used to evaluate the apparent activation energy (Ea), the pre-exponential factor (Aα) and the overall reaction order (n). Maximum SO2 peak at 300°C and 950°C (from TG-MS), indicates that slow pyrolysis at 500°C, with a packed bed lime scrubber at the outlet during temperature rise, is the best suited thermochemical pathway for energy harnessing.

  15. Exploiting Differential Gene Expression and Epistasis to Discover Candidate Genes for Drought-Associated QTLs in Arabidopsis thaliana

    PubMed Central

    Lovell, John T.; Mullen, Jack L.; Lowry, David B.; Awole, Kedija; Richards, James H.; Sen, Saunak; Verslues, Paul E.; Juenger, Thomas E.; McKay, John K.

    2015-01-01

    Soil water availability represents one of the most important selective agents for plants in nature and the single greatest abiotic determinant of agricultural productivity, yet the genetic bases of drought acclimation responses remain poorly understood. Here, we developed a systems-genetic approach to characterize quantitative trait loci (QTLs), physiological traits and genes that affect responses to soil moisture deficit in the TSUxKAS mapping population of Arabidopsis thaliana. To determine the effects of candidate genes underlying QTLs, we analyzed gene expression as a covariate within the QTL model in an effort to mechanistically link markers, RNA expression, and the phenotype. This strategy produced ranked lists of candidate genes for several drought-associated traits, including water use efficiency, growth, abscisic acid concentration (ABA), and proline concentration. As a proof of concept, we recovered known causal loci for several QTLs. For other traits, including ABA, we identified novel loci not previously associated with drought. Furthermore, we documented natural variation at two key steps in proline metabolism and demonstrated that the mitochondrial genome differentially affects genomic QTLs to influence proline accumulation. These findings demonstrate that linking genome, transcriptome, and phenotype data holds great promise to extend the utility of genetic mapping, even when QTL effects are modest or complex. PMID:25873386

  16. Influence of affinity on antibody determination in microtiter ELISA systems

    SciTech Connect

    Peterman, J.H.; Voss, E.W. Jr.; Butler, J.E.

    1986-03-01

    Theoretically, all immunoassays are affinity (Ka) dependent when the product of the antibody (Ab) Ka and the free epitope concentration is less than 10. Thus, the degree of dependence on Ka depends on the concentration of available antigen in the system. The authors examined the binding of /sup 125/I-anti-fluorescein (a-FLU) monoclonal antibodies of different affinities to FLU-gelatin adsorbed on Immunlon 2 microtiter plates. Data obtained were in general agreement with our theoretical predictions; the percent of /sup 125/I-a-FLU which bound correlated with Ka, as did the shape of the titration curves. Measurement of 5 a-FLU monoclonals by the ELISA showed that the determination of Ab concentrations depends on the FLU-gelatin concentration, epitope density, and on the relationship between the Kas of test samples and the reference standard Ab preparation. Thus the ELISA is Ka dependent and should not be used routinely to estimate the absolute amount to Ab in unknown samples. However, the Ka dependency of the ELISA might provide a convenient assay for the estimation of the relative functional Ka (rfKa) of antibody preparations.

  17. Synthesis, characterization and non-isothermal decomposition kinetics of manganese hypophosphite monohydrate

    NASA Astrophysics Data System (ADS)

    Noisong, Pittayagorn; Danvirutai, Chanaiporn; Srithanratana, Tipaporn; Boonchom, Banjong

    2008-11-01

    The manganese hypophosphite monohydrate (α-Mn(H 2PO 2) 2·H 2O) was synthesized and characterized by differential thermal analysis-thermogravimetry (TG/DTG/DTA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The thermal transformation products form the synthesized Mn(H 2PO 2) 2·H 2O according to the thermal treatment at 160 and 450 °C were found to be α-Mn(H 2PO 2) 2· xH 2O and Mn 2P 2O 7, respectively. The activation energies of two decomposition reaction steps of Mn(H 2PO 2) 2·H 2O were calculated through the isoconversional methods of Ozawa and KAS. The obtained activation energies can be concluded that the reactions of the dehydration and the decomposition steps for Mn(H 2PO 2) 2·H 2O were the single and multi-step mechanisms, respectively.

  18. Thermal analysis and kinetics of coal during oxy-fuel combustion

    NASA Astrophysics Data System (ADS)

    Kosowska-Golachowska, Monika

    2017-08-01

    The pyrolysis and oxy-fuel combustion characteristics of Polish bituminous coal were studied using non-isothermal thermogravimetric analysis. Pyrolysis tests showed that the mass loss profiles were almost similar up to 870°C in both N2 and CO2 atmospheres, while further mass loss occurred in CO2 atmosphere at higher temperatures due to char-CO2 gasification. Replacement of N2 in the combustion environment by CO2 delayed the combustion of bituminous coal. At elevated oxygen levels, TG/DTG profiles shifted through lower temperature zone, ignition and burnout temperatures decreased and mass loss rate significantly increased and complete combustion was achieved at lower temperatures and shorter times. Kinetic analysis for the tested coal was performed using Kissinger-Akahira-Sunose (KAS) method. The activation energies of bituminous coal combustion at the similar oxygen content in oxy-fuel with that of air were higher than that in air atmosphere. The results indicated that, with O2 concentration increasing, the activation energies decreased.

  19. Comparative study on pyrolysis of lignocellulosic and algal biomass using a thermogravimetric and a fixed-bed reactor.

    PubMed

    Yuan, Ting; Tahmasebi, Arash; Yu, Jianglong

    2015-01-01

    Pyrolysis characteristics of four algal and lignocellulosic biomass samples were studied by using a thermogravimetric analyzer (TGA) and a fixed-bed reactor. The effects of pyrolysis temperature and biomass type on the yield and composition of pyrolysis products were investigated. The average activation energy for pyrolysis of biomass samples by FWO and KAS methods in this study were in the range of 211.09-291.19kJ/mol. CO2 was the main gas component in the early stage of pyrolysis, whereas H2 and CH4 concentrations increased with increasing pyrolysis temperature. Bio-oil from Chlorellavulgaris showed higher content of nitrogen containing compounds compared to lignocellulosic biomass. The concentration of aromatic organic compounds such as phenol and its derivatives were increased with increasing pyrolysis temperature up to 700°C. FTIR analysis results showed that with increasing pyrolysis temperature, the concentration of OH, CH, CO, OCH3, and CO functional groups in char decreased sharply. Copyright © 2014 Elsevier Ltd. All rights reserved.

  20. Kinetics of thermal decomposition of some biomasses in an inert environment. An investigation of the effect of lead loaded by biosorption.

    PubMed

    Martín-Lara, María Ángeles; Iáñez-Rodríguez, Irene; Blázquez, Gabriel; Quesada, Lucía; Pérez, Antonio; Calero, Mónica

    2017-09-23

    The thermal behavior of some types of raw and lead-polluted biomasses typical in south Spain was studied by non-isothermal thermogravimetry. Experiments were carried out in nitrogen atmosphere at three heating rates (5, 10 and 20°C/min). The results of thermogravimetric tests carried out proved that the presence of lead did not change the main degradation pathways of selected biomass (almond shell (AS) and olive pomace (OP)). However, from a point of view of mass loss, lead-polluted samples showed higher decomposition temperatures and decomposition at higher rate. The determination of activation energies was performed by isoconversional methods of Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Friedman (FR). In general, lead-polluted samples showed lower activation energies than raw ones. Then, Coast-Redfern method was applied to determine kinetic function. The kinetic function that seems to determine the mechanism of thermal degradation of main components of all samples was nth order reaction. Finally, a model based on three parallel reactions (for three pseudocomponents) that fit to nth order reactions was evaluated. This model was appropriate to predict the pyrolysis behavior of the raw and lead-polluted samples in all pyrolysis conditions studied. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. COMPASS Final Report: Lunar Communications Terminal (LCT)

    NASA Technical Reports Server (NTRS)

    Oleson, Steven R.; McGuire, Melissa L.

    2010-01-01

    The Lunar Communications Terminal (LCT) COllaborative Modeling and Parametric Assessment of Space Systems (COMPASS) session designed a terminal to provide communications between lunar South Pole assets, communications relay to/from these assets through an orbiting Lunar Relay Satellite (LRS) and navigation support. The design included a complete master equipment list, power requirement list, configuration design, and brief risk assessment and cost analysis. The Terminal consists of a pallet containing the communications and avionics equipment, surrounded by the thermal control system (radiator), an attached, deployable 10-m tower, upon which were mounted locally broadcasting and receiving modems and a deployable 1 m diameter Ka/S band dish which provides relay communications with the lunar relay satellites and, as a backup, Earth when it is in view. All power was assumed to come from the lunar outpost Habitat. Three LCT design options were explored: a stand-alone LCT servicing the manned outpost, an integrated LCT (into the Habitat or Lunar Lander), and a mini-LCT which provides a reduced level of communication for primarily robotic areas dealing as in situ resource utilization (ISRU) and remote science. Where possible all the designs assumed single fault tolerance. Significant mass savings were found when integrating the LCT into the Habitat or Lander but increases in costs occurred depending upon the level of man rating required for such designs.

  2. Myeloma Xenograft Destruction by a Nonviral Vector Delivering Oncolytic Infectious Nucleic Acid

    PubMed Central

    Hadac, Elizabeth M; Kelly, Elizabeth J; Russell, Stephen J

    2011-01-01

    The feasibility of using a nonviral vector formulation to initiate an oncolytic viral infection has not been previously demonstrated. We therefore sought to determine whether infectious nucleic acid (INA) could be used in place of virus particles to initiate an oncolytic picornavirus infection in vivo. Infectious RNA encoding coxsackievirus A21 (CVA21) was transcribed from plasmid DNA using T7 polymerase. Within 48 hours of injecting this RNA into KAS6/1 myeloma xenografts, high titers of infectious CVA21 virions were detected in the bloodstream. Tumors regressed rapidly thereafter and mice developed signs of myositis. At euthanasia, CVA21 was recovered from regressing tumors and from skeletal muscles. Treatment outcomes were comparable following intratumoral injection of naked RNA or fully infectious CVA21 virus. Dose–response studies showed that an effective oncolytic infection could be established by intratumoral injection of 1 µg of infectious RNA. The oncolytic infection could also be initiated by intravenous injection of infectious RNA. Our study demonstrates that INA is a highly promising alternative drug formulation for oncolytic virotherapy. PMID:21505425

  3. Genetics of Local Adaptation in the Laboratory: Flowering Time Quantitative Trait Loci under Geographic and Seasonal Conditions in Arabidopsis

    PubMed Central

    Li, Yan; Roycewicz, Peter; Smith, Evadne; Borevitz, Justin O.

    2006-01-01

    Flowering time in Arabidopsis thaliana is controlled by a large number of genes and various environmental factors, such as light and temperature. The objective of this study was to identify flowering time quantitative trait loci (QTL) under growth conditions simulating seasonal conditions from native geographic locations. Our growth chambers were set to simulate the spring conditions in Spain and Sweden, with appropriate changes in light color, intensity and day length, as well as temperature and relative humidity. Thus the Sweden-like spring conditions changed more dramatically compared to Spain-like spring conditions across the duration of our experiment. We have used these conditions to map QTL responsible for flowering time in the Kas-1/Col-gl1 recombinant inbred lines (RILs) across two replicate blocks. A linkage map from 96 RILs was established using 119 markers including 64 new SNPs markers. One major QTL, mapping to the FRIGIDA (FRI) locus, was detected on the top of chromosome 4 that showed significant gene×seasonal environment interactions. Three other minor QTL also were detected. One QTL mapping near FLOWERING LOCUS M (FLM) showed an epistatic interaction with the QTL at FRI. These QTL×environment and QTL×QTL interactions suggest that subtle ecologically relevant changes in light, temperature, and relative humidity are differentially felt by alleles controlling flowering time and may be responsible for adaptation to regional environments. PMID:17205109

  4. Degradation of anionic surfactants during drying of UASBR sludges on sand drying beds.

    PubMed

    Mungray, Arvind Kumar; Kumar, Pradeep

    2008-09-01

    Anionic surfactant (AS) concentrations in wet up-flow anaerobic sludge blanket reactor (UASBR) sludges from five sewage treatment plants (STPs) were found to range from 4480 to 9,233 mg kg(-1)dry wt. (average 7,347 mg kg(-1)dry wt.) over a period of 18 months. After drying on sand drying beds (SDBs), AS in dried-stabilized sludges averaged 1,452 mg kg(-1)dry wt., a reduction of around 80%. The kinetics of drying followed simple first-order reduction of moisture with value of drying constant (k(d))=0.051 d(-1). Reduction of AS also followed first-order kinetics. AS degradation rate constant (k(AS)) was found to be 0.034 d(-1) and half-life of AS as 20 days. The order of rates of removal observed was k(d)>k(AS)>k(COD)>k(OM) (drying >AS degradation>COD reduction>organic matter reduction). For the three applications of dried-stabilized sludges (soil, agricultural soil, grassland), values of risk quotient (RQ) were found to be <1, indicating no risk.

  5. Coupled Electron and Proton Transfer Reactions during the O→E Transition in Bovine Cytochrome c Oxidase

    PubMed Central

    Popović, Dragan M.; Stuchebrukhov, Alexei A.

    2014-01-01

    A combined DFT/electrostatic approach is employed to study the coupling of proton and electron transfer reactions in cytochrome c oxidase (CcO) and its proton pumping mechanism. The coupling of the chemical proton to the internal electron transfer between heme a and the binuclear center is examined for the O→E transition. The novel features of the His291 pumping model are proposed, which involve timely well-synchronized sequence of the proton-coupled electron transfer reactions. The obtained pKas and Ems of the key ionizable and redox-active groups at the different stages of the O→E transition are consistent with available experimental data. The PT step from E242 to H291 is examined in detail for various redox states of the hemes and various conformations of E242 side-chain. Redox potential calculations of the successive steps in the reaction cycle during the O→E transition are able to explain a cascade of equilibria between the different intermediate states and electron redistribution between the metal centers during the course of the catalytic activity. All four electrometric phases are discussed in the light of the obtained results, providing a robust support for the His291 model of proton pumping in CcO. PMID:22086149

  6. Greenhouse Gas Emission Reduction Due to Improvement of Biodegradable Waste Management System

    NASA Astrophysics Data System (ADS)

    Bendere, R.; Teibe, I.; Arina, D.; Lapsa, J.

    2014-12-01

    ārdāmo atkritumu apsaimniekošanas statistikas datu novērtējums atbilstoši likumdošanas prasībām. Izmantojot matemātisko modelēšanas programmu WAMPS, analizēti trīs dažādi bioloģisko noārdāmo atkritumu apsaimniekošanas scenāriji, kuriem veikts vides ietekmes novērtējums, kas izteikts klimata pārmaiņu potenciālā - tonnas CO2 ekv. Darbā secināts, ka lielākais siltumnīcefektu (SEG) avots atkritumu apsaimniekošanas ir atkritumu poligoni (Bāzes scenārijs), ko galvenokārt ietekmē CH4 rašanās, organiskajiem atkritumiem sadaloties anaerobos apstākļos. Būtisku pozitīvo efektu SEG emisiju samazināšanā dod atkritumu pārstrāde otrreizējās izejvielās un sadedzināšana cementa ražotnē, kas ļauj samazināt dabīgo izejmateriālu un fosilo enerģijas resursu patēriņu. Attīstot pārtikas atkritumu pārstrādi biogāzē, lietderīgi veidot alternatīvās vai izmantot esošās sistēmas, kas nodrošina iegūtās enerģijas un digestāta patēriņu, t.i lauksaimniecība, transports vai komunālie pakalpojumi. Lai no zaļajiem dārza atkritumiem iegūtu augstvērtīgu kompostu, valstī jārada tam nepieciešami likumdošanas un ekonomiskie instrumenti, kas veicina komposta tirgus attīstību.

  7. Thermal decomposition kinetics of sorghum straw via thermogravimetric analysis.

    PubMed

    Dhyani, Vaibhav; Kumar, Jitendra; Bhaskar, Thallada

    2017-09-01

    The thermal decomposition of sorghum straw was investigated by non-isothermal thermogravimetric analysis, where the determination of kinetic triplet (activation energy, pre-exponential factor, and reaction model), was the key objective. The activation energy was determined using different isoconversional methods: Friedman, Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS), Starink, Iterative method of Chai & Chen, Vyazovkin AIC method, and Li & Tang equation. The pre-exponential factor was calculated using Kissinger's equation; while the reaction model was predicted by comparison of z-master plot obtained from experimental values with the theoretical plots. The values of activation energy obtained from isoconversional methods were further used for evaluation of thermodynamic parameters, enthalpy, entropy and Gibbs free energy. Results showed three zones of pyrolysis having average activation energy values of 151.21kJ/mol, 116.15kJ/mol, and 136.65kJ/mol respectively. The data was well fitting with two-dimension 'Valensi' model for conversion values from 0 to 0.4 with a coefficient of determination (R(2)) value of 0.988, and with third order reaction model for values from 0.4 to 0.9 with an R(2) value of 0.843. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Enhanced astaxanthin production from Haematococcus pluvialis using butylated hydroxyanisole.

    PubMed

    Shang, Minmin; Ding, Wei; Zhao, Yongteng; Xu, Jun-Wei; Zhao, Peng; Li, Tao; Ma, Huixian; Yu, Xuya

    2016-10-20

    Haematococcus pluvialis is a promising natural source of high-value antioxidant astaxanthin under stress conditions. Biotic or abiotic elicitors are effective strategies for improving astaxanthin production in H. pluvialis. Butylated hydroxyanisole (BHA) was identified as an effective inducer for H. pluvialis LUGU. Under a treatment of 2mgL(-1) BHA (BHA2), astaxanthin content reached a maximum of 29.03mgg(-1) dry weight (DW) (2.03-fold of that in the control) after 12day of the mid-exponential growth phase. Subsequently, H. pluvialis LUGU was subjected to BHA2 at different growth phases because an appropriate time node for adding elicitors is vital for the entire production to succeed. As a result, the highest astaxanthin content (29.3mgg(-1) DW) was obtained in cells on day 14 (BHA2 14) of the late-exponential growth phase. Furthermore, the samples treated with BHA2 14 and the control group were compared in terms of the transcriptional expression of seven carotenogenesis genes, fatty acid composition, and total accumulated astaxanthin. All selected genes exhibited up-regulated expression profiles, with chy, crtO, and bkt exhibiting higher maximum transcriptional levels than the rest. Oleic acid content increased 33.15-fold, with acp, fad, and kas expression being enhanced on the day when astaxanthin was produced rapidly.

  9. Hydrothermal growth of potassium titanyl arsenate (KTA) in large autoclaves

    NASA Astrophysics Data System (ADS)

    Belt, Roger F.; Ings, John B.

    1993-03-01

    Solubility and phase relations were investigated for selected K/As ratios in KH2AsO4-KOH solutions at 600°C and 2040 atm. All initial data were obtained with 5 mm diameter x 50 mm long platinum capsules in Tem-Pres type autoclaves. The most favorable results were repeated in Morey type autoclaves of 2.2 cm diameter. The P-V-T data were generated and extrapolated for use in gold liners and René 41 autoclaves with a pressure balancing method. Transfer to the 3.8 cm diameter x 46 cm long autoclaves with gold liners was achieved. Both nutrient and larger seed crystals were grown from a K2WO4-Li2WO4 flux. The internal and external degrees of fill were adjusted to obtain a balance of pressure at 1700 atm and 590°C. Initial growth runs were made for 1-2 weeks under a gradient of 30°C with a 4 molar KH2AsO4 mineralizer. Natural facet seeds were employed first while later runs utilized (011) cut and polished seeds.

  10. Combustion characteristics and kinetics of anthracite with added chlorine

    NASA Astrophysics Data System (ADS)

    Wang, Cui; Zhang, Jian-liang; Wang, Guang-wei; Jiao, Ke-xin; Liu, Zheng-jian; Chou, Kuo-chih

    2017-07-01

    The combustion process of Yangquan anthracite (YQ) with the addition of 0.045wt%, 0.211wt%, 1.026wt%, and 2.982wt% chlorine was investigated using a thermogravimetric method from an ambient temperature to 1173 K in an air atmosphere. Results show that the YQ combustion characteristics are not significantly affected by an increase in chlorine content. Data acquired for combustion conversion are then further processed for kinetic analysis. Average apparent activation energies determined using the model-free method (specifically the KAS method) are 103.025, 110.250, 99.906, and 110.641 kJ/mol, respectively, and the optimal kinetic model for describing the combustion process of chlorine-containing YQ is the nucleation kinetic model, as determined by the z( α) master plot method. The mechanism function of the nucleation kinetic model is then employed to estimate the pre-exponential factor, by making use of the compensation effect. The kinetic models to describe chlorine-containing YQ combustion are thus obtained through advanced determination of the optimal mechanism function, average apparent activation energy, and the pre-exponential factor.

  11. Characterization and thermal dehydration kinetics of highly crystalline mcallisterite, synthesized at low temperatures.

    PubMed

    Moroydor Derun, Emek; Senberber, Fatma Tugce

    2014-01-01

    The hydrothermal synthesis of a mcallisterite (Mg2(B6O7(OH)6)2 · 9(H2O)) mineral at low temperatures was characterized. For this purpose, several reaction temperatures (0-70°C) and reaction times (30-240 min) were studied. Synthesized minerals were subjected to X-ray diffraction (XRD), fourier transform infrared (FT-IR), and Raman spectroscopies and scanning electron microscopy (SEM). Additionally, experimental analyses of boron trioxide (B2O3) content and reaction yields were performed. Furthermore, thermal gravimetry and differential thermal analysis (TG/DTA) were used for the determination of thermal dehydration kinetics. According to the XRD results, mcallisterite, which has a powder diffraction file (pdf) number of "01-070-1902," was formed under certain reaction parameters. Pure crystalline mcallisterite had diagnostic FT-IR and Raman vibration peaks and according to the SEM analysis, for the minerals which were synthesized at 60°C and 30 min of reaction time, particle size was between 398.30 and 700.06 nm. Its B2O3 content and reaction yield were 50.80 ± 1.12% and 85.80 ± 0.61%, respectively. Finally, average activation energies (conversion values (α) that were selected between 0.1 and 0.6) were calculated as 100.40 kJ/mol and 98.31 kJ/mol according to Ozawa and Kissinger-Akahira-Sunose (KAS) methods, respectively.

  12. A liquid chromatography-tandem mass spectrometry method for measurement of N-modified phosphatidylethanolamines.

    PubMed

    Guo, Lilu; Amarnath, Venkataraman; Davies, Sean S

    2010-10-15

    N-Acyl phosphatidylethanolamines (NAPEs) are synthesised in response to stress in a variety of organisms from bacteria to humans. More recently, nonenzymatic modification of the ethanolamine headgroup of phosphatidylethanolamine (PE) by various aldehydes, including levuglandins/isoketals (which are gamma-ketoaldehydes [gammaKAs] derived from arachidonic acid), has also been demonstrated. The levels of these various N-modified PEs formed during stress and their biological significance remain to be fully characterized. Such studies require an accurate, facile, and cost-effective method for quantifying N-modified PEs. Previously, NAPE and some of the nonenzymatically N-modified PE species have been quantified by mass spectrometry after hydrolysis to their constituent N-acylethanolamine by enzymatic hydrolysis, most typically with Streptomyces chromofuscus phospholipase D. However, enzymatic hydrolysis is not cost-effective for routine analysis of a large number of samples, and hydrolytic efficiency may vary for different N-modified PEs, making quantitation more difficult. Therefore, we sought a robust and inexpensive chemical hydrolysis approach. Methylamine (CH(3)NH(2))-mediated deacylation has previously been used in headgroup analysis of phosphatidylinositol phosphates. Therefore, we developed an accurate assay for NAPEs and gammaKA-PEs using CH(3)NH(2)-mediated deacylation and quantitation of the resulting glycerophospho-N-modified ethanolamines by liquid chromatography-tandem mass spectrometry. Copyright 2010 Elsevier Inc. All rights reserved.

  13. A new genus and family for the misclassified chytrid, Rhizophlyctis harderi.

    PubMed

    Powell, Martha J; Letcher, Peter M; Chambers, James G; Roychoudhury, Sonali

    2015-01-01

    A chytrid first discovered in Mediterranean sands and called Rhizophlyctis harderi was classified in the genus Rhizophlyctis based on its interbiotic vegetative thalli with multiple rhizoidal axes and resting thalli with tufts of rhizoid-like appendages. Developmental, electron microscopic and molecular analyses, however, have brought into question the proper placement of this chytrid. Because its original description was in German and not Latin, the name R. harderi is not validly published. We found that this chytrid produces three thallus forms that could place it in three different morpho-genera: Rhizophydium, Phlyctochytrium or Rhizophlyctis. The ultrastructural architecture of its zoospore is different from that of zoospores of Rhizophlyctis rosea, the type species for Rhizophlyctis, and shares zoospore ultrastructural characteristics with the Rhizophydiales. Zoospores of this chytrid exhibit a distinctive kinetosome-associated structure (KAS), a curved shield bridged to two of the kinetosomal triplets and a layered cap anterior to the kinetosome. Phylogenetic analyses of nuc rDNA also support the placement of this chytrid in the Rhizophydiales and not in the Rhizophlyctidales. Given its molecularly based phylogenetic placement and its distinctive zoospore architecture, we describe this chytrid in a new genus, Uebelmesseromyces, in the Rhizophydiales and erect Uebelmesseromycetaceae as a new family to accommodate it. © 2015 by The Mycological Society of America.

  14. Depth: a web server to compute depth, cavity sizes, detect potential small-molecule ligand-binding cavities and predict the pKa of ionizable residues in proteins

    PubMed Central

    Tan, Kuan Pern; Nguyen, Thanh Binh; Patel, Siddharth; Varadarajan, Raghavan; Madhusudhan, M. S.

    2013-01-01

    Residue depth accurately measures burial and parameterizes local protein environment. Depth is the distance of any atom/residue to the closest bulk water. We consider the non-bulk waters to occupy cavities, whose volumes are determined using a Voronoi procedure. Our estimation of cavity sizes is statistically superior to estimates made by CASTp and VOIDOO, and on par with McVol over a data set of 40 cavities. Our calculated cavity volumes correlated best with the experimentally determined destabilization of 34 mutants from five proteins. Some of the cavities identified are capable of binding small molecule ligands. In this study, we have enhanced our depth-based predictions of binding sites by including evolutionary information. We have demonstrated that on a database (LigASite) of ∼200 proteins, we perform on par with ConCavity and better than MetaPocket 2.0. Our predictions, while less sensitive, are more specific and precise. Finally, we use depth (and other features) to predict pKas of GLU, ASP, LYS and HIS residues. Our results produce an average error of just <1 pH unit over 60 predictions. Our simple empirical method is statistically on par with two and superior to three other methods while inferior to only one. The DEPTH server (http://mspc.bii.a-star.edu.sg/depth/) is an ideal tool for rapid yet accurate structural analyses of protein structures. PMID:23766289

  15. A study of switchgrass pyrolysis: Product variability and reaction kinetics

    NASA Astrophysics Data System (ADS)

    Bovee, Jonathan Matthew

    Samples of the same cultivar of cave-in-rock switchgrass were harvested from plots in Frankenmuth, Roger City, Cass County, and Grand Valley, Michigan. It was determined that variation exists, between locations, among the pyrolytic compounds which can lead to variability in bio-oil and increased processing costs at bio-refineries to make hydrocarbon fuels. Washed and extractives-free switchgrass samples, which contain a lower alkali and alkaline earth metals content than untreated samples, were shown to produce lower amounts of acids, esters, furans, ketones, phenolics, and saccharides and also larger amounts of aldehydes upon pyrolysis. Although the minerals catalyzed pyrolytic reactions, there was no evidence indicating their effect on reducing the production of anhydrosugars, specifically levoglucosan. To further link minerals present in the biomass to a catalytic pathway, mathematic models were employed to determine the kinetic parameters of the switchgrass. While the calculated activation energies of switchgrass, using the FWO and KAS methods, were 227.7 and 217.8 kJ/mol, correspondingly, it was concluded that the activation energies for the switchgrass hemicellulose and cellulose peaks were 115.5 and 158.2 kJ/mol, respectively, using a modified model-fitting method. The minerals that effect the production of small molecules and levoglucosan also have an observable catalytic effect on switchgrass reaction rate, which may be quantifiable through the use of reaction kinetics so as to determine activation energy.

  16. Zoospore ultrastructure and phylogenetic position of Phlyctochytrium aureliae Ajello is revealed (Chytridiaceae, Chytridiales, Chytridiomycota).

    PubMed

    Letcher, Peter M; Powell, Martha J; Picard, Kathryn T

    2012-01-01

    From forest soils in Scotland Phlyctochytrium aureliae was observed and brought into pure culture. Previously included in a molecular phylogenetic study of Chytridiales as Phlyctochytrium sp. KP 061, the organism groups with Phlyctochytrium planicorne, P. bullatum, Chytridium olla and C. lagenaria in the family Chytridiaceae. Thallus morphology and development as well as zoospore ultrastructure are detailed herein. The sporangium is epibiotic, spherical or subspherical, apophysate or non-apophysate, and ornamented with dentate enations. The overall zoospore ultrastructural features are consistent with the Group II type zoospore that characterizes family Chytridiaceae in the Chytridiales, although the zoospore also has two character states unique to this taxon: the MLC cisterna fenestrations are one-third to one-half the diameter of fenestrations in other Chytridiaceae zoospores and an accumulation of electron-dense material (a kinetosome-associated structure, or KAS) proximal to the kinetosome and non-flagellated centriole is extensive and unique. This study verifies that zoospore ultrastructure of P. aureliae zoospores places this species in the Chytridiales and Chytridiaceae, as indicated in a previous molecular phylogenetic study.

  17. Non-isothermal kinetic study of de-oiled seeds cake of African star apple (Chrosophyllum albidum) using thermogravimetry.

    PubMed

    Sokoto, M A; Singh, Rawel; Krishna, Bhavya B; Kumar, Jitendra; Bhaskar, Thallada

    2016-10-01

    Thermal decomposition and kinetics behaviour of the de-oiled seed cake of African star apple (Chrosophyllum albidum) has been investigated using thermogravimetry under the nitrogen atmosphere from ambient temperature to 900 °C. The thermogravimetric data for the cake decomposition at six different heating rates (5, 10, 15, 20, 30 and 40 °C/min) were used to evaluate the kinetic decomposition of the cake using Friedman (FD), Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) models. Thermal decomposition of the cake showed thermograms indicating dehydration and devolitilization stages (200-400 °C). The maximum temperature for the decomposition of the cake (Tmax) increases from 289.42-335.96 °C with increase in heating rates. The average apparent activation energy (Ea) values of 153.15, 145.14 and 147.15 kJ/mol were calculated using Friedman, Kissinger-Akahira-Sunose, and Flynn-Wall-Ozawa models respectively. The extent of mass conversion (α) shows dependence on apparent activation Ea values which is an evidence of multi-step decomposition kinetic. The thermal profile and kinetic data obtained could be helpful in evaluating the thermal stability of the cake as well as modeling, designing and developing a thermo-chemical system for the conversion of the cake to fuel.

  18. Influence of external chloride concentration on the kinetics of mobile charges in the cell membrane of Valonia utricularis

    PubMed Central

    Wang, Jianning; Wehner, Günter; Benz, Roland; Zimmermann, Ulrich

    1991-01-01

    Charge pulse relaxation studies were performed on cells of the giant marine alga Valonia utricularis. Two exponential voltage relaxations were recorded as found previously (Benz, R., and U. Zimmermann. 1983. Biophys. J. 43:13-26.). The parameters of the two exponential voltage decays were studied as a function of the chloride concentration in the artificial sea water. Replacement of external chloride by 2(N-morpholino)ethanesulfonate (Mes-) had a dramatic influence on the four relaxation parameters. This chloride dependence could not be satisfactorily explained by the simplified model used earlier. Accordingly, additional reaction steps had to be included in the model. Only two relaxation processes could be resolved under all experimental conditions. This means that the heterogeneous complexation reactions, kR (association), and kD (dissociation) were too fast to be resolved. Therefore a carrier model with equilibrium heterogeneous surface reactions was used to fit the experimental results. From the charge pulse data at different chloride concentrations the translocation rate constants of the free and complexed carriers, kS and kAS, through the membrane, as well as the total surface concentration of carrier systems, N0, could be evaluated. The results described here indicate that the cell membrane of Valonia utricularis contains an electrogenic transport system for chloride. PMID:19431785

  19. Comparative Studies of the Pyrolytic and Kinetic Characteristics of Maize Straw and the Seaweed Ulva pertusa

    PubMed Central

    Ye, Naihao; Li, Demao; Chen, Limei; Zhang, Xiaowen; Xu, Dong

    2010-01-01

    Seaweed has attracted considerable attention as a potential biofuel feedstock. The pyrolytic and kinetic characteristics of maize straw and the seaweed Ulva pertusa were studied and compared using heating rates of 10, 30 and 50°C min−1 under an inert atmosphere. The activation energy, and pre-exponential factors were calculated by the Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Popescu methods. The kinetic mechanism was deduced by the Popescu method. The results indicate that there are three stages to the pyrolysis; dehydration, primary devolatilization and residual decomposition. There were significant differences in average activation energy, thermal stability, final residuals and reaction rates between the two materials. The primary devolatilization stage of U. pertusa can be described by the Avramic-Erofeev equation (n = 3), whereas that of maize straw can be described by the Mampel Power Law (n = 2). The average activation energy of maize straw and U. pertusa were 153.0 and 148.7 KJ mol−1, respectively. The pyrolysis process of U.pertusa would be easier than maize straw. And co-firing of the two biomass may be require less external heat input and improve process stability. There were minor kinetic compensation effects between the pre-exponential factors and the activation energy. PMID:20844751

  20. Physical, kinetic and spectrophotometric studies of a NAD(P)-dependent benzaldehyde dehydrogenase from Pseudomonas putida ATCC 12633.

    PubMed

    Yeung, Catherine K; Yep, Alejandra; Kenyon, George L; McLeish, Michael J

    2008-09-01

    The mandelate pathway of Pseudomonas putida ATCC 12633 comprises five enzymes and catalyzes the conversion of R- and S-mandelamide to benzoic acid which subsequently enters the beta-ketoadipate pathway. Although the first four enzymes have been extensively characterized the terminal enzyme, a NAD(P)+-dependent benzaldehyde dehydrogenase (BADH), remains largely undescribed. Here we report that BADH is a dimer in solution, and that DTT is necessary both to maintain the activity of BADH and to prevent oligimerization of the enzyme. Site-directed mutagenesis confirms that Cys249 is the catalytic cysteine and identifies Cys140 as the cysteine likely to be involved in inter-monomer disulfide formation. BADH can utilize a range of aromatic substrates and will also operate efficiently with cyclohexanal as well as medium-chain aliphatic aldehydes. The logV and logV/K pH-rate profiles for benzaldehyde with either NAD+ or NADP+ as the coenzyme are both bell-shaped. The pKa values on the ascending limb range from 6.2 to 7.1 while those on the descending limb range from 9.6 to 9.9. A spectrophotometric approach was used to show that the pKa of Cys249 was 8.4, i.e., Cys249 is not responsible for the pKas observed in the pH-rate profiles.

  1. Genome scale transcriptional response diversity among ten ecotypes of Arabidopsis thaliana during heat stress.

    PubMed

    Barah, Pankaj; Jayavelu, Naresh D; Mundy, John; Bones, Atle M

    2013-01-01

    In the scenario of global warming and climate change, heat stress is a serious threat to crop production worldwide. Being sessile, plants cannot escape from heat. Plants have developed various adaptive mechanisms to survive heat stress. Several studies have focused on diversity of heat tolerance levels in divergent Arabidopsis thaliana (A. thaliana) ecotypes, but comprehensive genome scale understanding of heat stress response in plants is still lacking. Here we report the genome scale transcript responses to heat stress of 10 A. thaliana ecotypes (Col, Ler, C24, Cvi, Kas1, An1, Sha, Kyo2, Eri, and Kond) originated from different geographical locations. During the experiment, A. thaliana plants were subjected to heat stress (38°C) and transcript responses were monitored using Arabidopsis NimbleGen ATH6 microarrays. The responses of A. thaliana ecotypes exhibited considerable variation in the transcript abundance levels. In total, 3644 transcripts were significantly heat regulated (p < 0.01) in the 10 ecotypes, including 244 transcription factors and 203 transposable elements. By employing a systems genetics approach- Network Component Analysis (NCA), we have constructed an in silico transcript regulatory network model for 35 heat responsive transcription factors during cellular responses to heat stress in A. thaliana. The computed activities of the 35 transcription factors showed ecotype specific responses to the heat treatment.

  2. Blockade of interleukin-6 signalling with siltuximab enhances melphalan cytotoxicity in preclinical models of multiple myeloma.

    PubMed

    Hunsucker, Sally A; Magarotto, Valeria; Kuhn, Deborah J; Kornblau, Steven M; Wang, Michael; Weber, Donna M; Thomas, Sheeba K; Shah, Jatin J; Voorhees, Peter M; Xie, Hong; Cornfeld, Mark; Nemeth, Jeffrey A; Orlowski, Robert Z

    2011-03-01

    Signalling through the interleukin (IL)-6 pathway induces proliferation and drug resistance of multiple myeloma cells. We therefore sought to determine whether the IL-6-neutralizing monoclonal antibody siltuximab, formerly CNTO 328, could enhance the activity of melphalan, and to examine some of the mechanisms underlying this interaction. Siltuximab increased the cytotoxicity of melphalan in KAS-6/1, INA-6, ANBL-6, and RPMI 8226 human myeloma cell lines (HMCLs) in an additive-to-synergistic manner, and sensitized resistant RPMI 8226.LR5 cells to melphalan. These anti-proliferative effects were accompanied by enhanced activation of drug-specific apoptosis in HMCLs grown in suspension, and in HMCLs co-cultured with a human-derived stromal cell line. Siltuximab with melphalan enhanced activation of caspase-8, caspase-9, and the downstream effector caspase-3 compared with either of the single agents. This increased induction of cell death occurred in association with enhanced Bak activation. Neutralization of IL-6 also suppressed signalling through the phosphoinositide 3-kinase/Akt pathway, as evidenced by decreased phosphorylation of Akt, p70 S6 kinase and 4E-BP1. Importantly, the siltuximab/melphalan regimen demonstrated enhanced anti-proliferative effects against primary plasma cells derived from patients with myeloma, monoclonal gammopathy of undetermined significance, and amyloidosis. These studies provide a rationale for translation of siltuximab into the clinic in combination with melphalan-based therapies.

  3. Burkholderia pseudomallei γ-carbonic anhydrase is strongly activated by amino acids and amines.

    PubMed

    Vullo, Daniela; Del Prete, Sonia; Osman, Sameh M; AlOthman, Zeid; Capasso, Clemente; Donald, William A; Supuran, Claudiu T

    2017-01-01

    Activation of the γ-class carbonic anhydrase (CAs, EC 4.2.1.1) from the pathogenic bacterium Burkholderia pseudomallei (BpsγCA) with a series of natural and non-natural amino acids and aromatic/heterocyclic amines has been investigated. The best BpsγCA activators were d-His, l-DOPA, d-Trp, 4-amino-l-Phe, dopamine, 2-(2-aminoethyl)pyridine, 2-aminoethyl-piparazine/morpholine and l-adrenaline, which showed activation constants ranging between 9 and 86nM. The least effective activators were l-His, l-Phe and 2-pyridyl-methylamine, with KAs in the range of 1.73-24.7μM. As little is known about the role of γ-CAs in the lifecycle and virulence of this saprophytic bacterium, this study may shed some light on such phenomena. This is the first CA activation study of a γ-CA from a pathogenic bacterium, the only other such study being on the enzyme discovered in the archaeon Methanosarcina thermophila, Cam. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Isoconversional and Isokinetic Studies of 2605SA1 Metglass

    NASA Astrophysics Data System (ADS)

    Lilly Shanker Rao, T.; Shanker Rao, T.

    2015-02-01

    Isoconversional methods (KAS,OFW,Li-Tang,and Vyazovkin) as well as isokinetic methods ((IKP) and CR) are used to determine the activation energy for crystallization (E), pre-exponential factor (A) and the conversion function f(α), for Fe-based 2605SA1 metallic glass.The non-isothennal differential scanning calorimetry data obtained at different heating rates ranging from 2 to 10 K/min are utilized for the analysis. The E for the peak I and II obtained by the IKP method are in good agreement with the values obtained from various isoconversional methods. The calculated kinetic triplets from IKP for peak I is: E = 445.6 ± 24 kJ/mol, A = 9.4 × 1022 sec-1 and f(α) = [-ln(l-α)]1/4 and for peak II is : E=325.7 ± 8 kJ/mol, A= 7.1 × 1015 sec-1 and f(α) = α1/4. All the above mentioned methods are summarized and discussed elaborately from the point of view of their applicability and correctness.

  5. Energy Consumption of Battery-Operated Screwdriver at Assembling Fixed Threaded Joints / Akumulatora Skrūvgrieža Elektroenerģijas Patēriņa Aprēķins, Veicot Nekustīga Vītņu Savienojuma Salikšanu Atkarībā No Operatora Reakcijas Laika

    NASA Astrophysics Data System (ADS)

    Grinevich, I.; Mozga, N.; Rudzitis, J.

    2013-10-01

    The electrical energy consumption of battery-operated screwdrivers, which are widely used in many industries, e.g. automotive, heavy, chemical, etc., can be considerably reduced. This would allow increasing the service life of a battery and reducing the time of its charging, thus increasing the productivity and decreasing the prime cost of this battery. It is shown that up to 17.9% of electrical energy could be saved at assembling fixed threaded joints by removing power from the screwdriver immediately after reaching the required tightening torque. Dotajā rakstā uzmanība tiek pievērsta akumulatora skrūvgrieža elektroenerģijas patēriņa samazināšanas iespējām sakarā ar problēmas aktualitāti šīs grupas plaši pielietotajiem instrumentiem. Elektroenerģijas patēriņa samazināšana masveida ražošanā, kur tiek izmantoti akumulatora skrūvgrieži, ļautu paildzināt akumulatora baterijas kalpošanas mūžu un samazināt uzlādēšanas laiku, kas, savukārt, novestu pie ražības palielināšanas un produkcijas pašizmaksas samazināšanas.

  6. Investigation of Structural Dynamics of Enzymes and Protonation States of Substrates Using Computational Tools

    PubMed Central

    Chang, Chia-En A.; Huang, Yu-Ming M.; Mueller, Leonard J.; You, Wanli

    2016-01-01

    This review discusses the use of molecular modeling tools, together with existing experimental findings, to provide a complete atomic-level description of enzyme dynamics and function. We focus on functionally relevant conformational dynamics of enzymes and the protonation states of substrates. The conformational fluctuations of enzymes usually play a crucial role in substrate recognition and catalysis. Protein dynamics can be altered by a tiny change in a molecular system such as different protonation states of various intermediates or by a significant perturbation such as a ligand association. Here we review recent advances in applying atomistic molecular dynamics (MD) simulations to investigate allosteric and network regulation of tryptophan synthase (TRPS) and protonation states of its intermediates and catalysis. In addition, we review studies using quantum mechanics/molecular mechanics (QM/MM) methods to investigate the protonation states of catalytic residues of β-Ketoacyl ACP synthase I (KasA). We also discuss modeling of large-scale protein motions for HIV-1 protease with coarse-grained Brownian dynamics (BD) simulations. PMID:27885336

  7. Benchmarking pKa prediction

    PubMed Central

    Davies, Matthew N; Toseland, Christopher P; Moss, David S; Flower, Darren R

    2006-01-01

    Background pKa values are a measure of the protonation of ionizable groups in proteins. Ionizable groups are involved in intra-protein, protein-solvent and protein-ligand interactions as well as solubility, protein folding and catalytic activity. The pKa shift of a group from its intrinsic value is determined by the perturbation of the residue by the environment and can be calculated from three-dimensional structural data. Results Here we use a large dataset of experimentally-determined pKas to analyse the performance of different prediction techniques. Our work provides a benchmark of available software implementations: MCCE, MEAD, PROPKA and UHBD. Combinatorial and regression analysis is also used in an attempt to find a consensus approach towards pKa prediction. The tendency of individual programs to over- or underpredict the pKa value is related to the underlying methodology of the individual programs. Conclusion Overall, PROPKA is more accurate than the other three programs. Key to developing accurate predictive software will be a complete sampling of conformations accessible to protein structures. PMID:16749919

  8. Analysis of dermatologic events in vemurafenib-treated patients with melanoma.

    PubMed

    Lacouture, Mario E; Duvic, Madeleine; Hauschild, Axel; Prieto, Victor G; Robert, Caroline; Schadendorf, Dirk; Kim, Caroline C; McCormack, Christopher J; Myskowski, Patricia L; Spleiss, Olivia; Trunzer, Kerstin; Su, Fei; Nelson, Betty; Nolop, Keith B; Grippo, Joseph F; Lee, Richard J; Klimek, Matthew J; Troy, James L; Joe, Andrew K

    2013-01-01

    Vemurafenib has been approved for the treatment of patients with advanced BRAF(V600E)-mutant melanoma. This report by the Vemurafenib Dermatology Working Group presents the characteristics of dermatologic adverse events (AEs) that occur in vemurafenib-treated patients, including cutaneous squamous cell carcinoma (cuSCC). Dermatologic AEs were assessed from three ongoing trials of BRAF(V600E) mutation-positive advanced melanoma. Histologic central review and genetic characterization were completed for a subset of cuSCC lesions. A total of 520 patients received vemurafenib. The most commonly reported AEs were dermatologic AEs, occurring in 92%-95% of patients. Rash was the most common AE (64%-75% of patients), and the most common types were rash not otherwise specified, erythema, maculopapular rash, and folliculitis. Rash development did not appear to correlate with tumor response. Photosensitivity occurred in 35%-63% of patients, and palmar-plantar erythrodysesthesia (PPE) occurred in 8%-10% of patients. The severity of rash, photosensitivity, and PPE were mainly grade 1 or 2. In all, 19%-26% of patients developed cuSCC, mostly keratoacanthomas (KAs). The majority of patients with cuSCC continued therapy without dose reduction after resection. Genetic analysis of 29 cuSCC/KA samples demonstrated HRAS mutations in 41%. Dermatologic AEs associated with vemurafenib treatment in patients with melanoma were generally manageable with supportive care measures. Dose interruptions and/or reductions were required in <10% of patients.

  9. Electron Flow through Nitrotyrosinate in Pseudomonas aeruginosa Azurin

    PubMed Central

    Warren, Jeffrey J.; Herrera, Nadia; Hill, Michael G.; Winkler, Jay R.; Gray, Harry B.

    2013-01-01

    We have designed ruthenium-modified Pseudomonas aeruginosa azurins that incorporate 3-nitrotyrosine (NO2YOH) between Ru(2,2′-bipyridine)2(imidazole)(histidine) and Cu redox centers in electron transfer (ET) pathways. We investigated the structures and reactivities of three different systems: RuH107NO2YOH109, RuH124NO2YOH122, and RuH126NO2YOH122. RuH107NO2YOH109, unlabeled H124NO2YOH122, and unlabeled H126NO2YOH122 were structurally characterized. The pKas of NO2YOH at positions 122 and 109 are 7.2 and 6.0, respectively. Reduction potentials of 3-nitrotyrosinate (NO2YO−)-modified azurins were estimated from cyclic and differential pulse voltammetry data: oxidation of NO2YO−122 occurs near 1.1 versus NHE; that for NO2YO−109 is near 1.2 V. Our analysis of transient optical spectroscopic experiments indicates that hopping via NO2YO− enhances CuI oxidation rates over single-step ET by factors of 32 (RuH107NO2YO−109), 46 (RuH126NO2YO−122), and 13 (RuH124NO2YO−122). PMID:23859602

  10. Analysis of Dermatologic Events in Vemurafenib-Treated Patients With Melanoma

    PubMed Central

    Duvic, Madeleine; Hauschild, Axel; Prieto, Victor G.; Robert, Caroline; Schadendorf, Dirk; Kim, Caroline C.; McCormack, Christopher J.; Myskowski, Patricia L.; Spleiss, Olivia; Trunzer, Kerstin; Su, Fei; Nelson, Betty; Nolop, Keith B.; Grippo, Joseph F.; Lee, Richard J.; Klimek, Matthew J.; Troy, James L.; Joe, Andrew K.

    2013-01-01

    Background. Vemurafenib has been approved for the treatment of patients with advanced BRAFV600E-mutant melanoma. This report by the Vemurafenib Dermatology Working Group presents the characteristics of dermatologic adverse events (AEs) that occur in vemurafenib-treated patients, including cutaneous squamous cell carcinoma (cuSCC). Methods. Dermatologic AEs were assessed from three ongoing trials of BRAFV600E mutation-positive advanced melanoma. Histologic central review and genetic characterization were completed for a subset of cuSCC lesions. Results. A total of 520 patients received vemurafenib. The most commonly reported AEs were dermatologic AEs, occurring in 92%–95% of patients. Rash was the most common AE (64%–75% of patients), and the most common types were rash not otherwise specified, erythema, maculopapular rash, and folliculitis. Rash development did not appear to correlate with tumor response. Photosensitivity occurred in 35%–63% of patients, and palmar-plantar erythrodysesthesia (PPE) occurred in 8%–10% of patients. The severity of rash, photosensitivity, and PPE were mainly grade 1 or 2. In all, 19%–26% of patients developed cuSCC, mostly keratoacanthomas (KAs). The majority of patients with cuSCC continued therapy without dose reduction after resection. Genetic analysis of 29 cuSCC/KA samples demonstrated HRAS mutations in 41%. Conclusions. Dermatologic AEs associated with vemurafenib treatment in patients with melanoma were generally manageable with supportive care measures. Dose interruptions and/or reductions were required in <10% of patients. PMID:23457002

  11. Hierarchical nuclear and cytoplasmic genetic architectures for plant growth and defense within Arabidopsis.

    PubMed

    Joseph, Bindu; Corwin, Jason A; Züst, Tobias; Li, Baohua; Iravani, Majid; Schaepman-Strub, Gabriela; Turnbull, Lindsay A; Kliebenstein, Daniel J

    2013-06-01

    To understand how genetic architecture translates between phenotypic levels, we mapped the genetic architecture of growth and defense within the Arabidopsis thaliana Kas × Tsu recombinant inbred line population. We measured plant growth using traditional size measurements and size-corrected growth rates. This population contains genetic variation in both the nuclear and cytoplasmic genomes, allowing us to separate their contributions. The cytoplasmic genome regulated a significant variance in growth but not defense, which was due to cytonuclear epistasis. Furthermore, growth adhered to an infinitesimal model of genetic architecture, while defense metabolism was more of a moderate-effect model. We found a lack of concordance between quantitative trait loci (QTL) regulating defense and those regulating growth. Given the published evidence proving the link between glucosinolates and growth, this is likely a false negative result caused by the limited population size. This size limitation creates an inability to test the entire potential genetic landscape possible between these two parents. We uncovered a significant effect of glucosinolates on growth once we accounted for allelic differences in growth QTLs. Therefore, other growth QTLs can mask the effects of defense upon growth. Investigating direct links across phenotypic hierarchies is fraught with difficulty; we identify issues complicating this analysis.

  12. New class of 19F pH indicators: fluoroanilines.

    PubMed Central

    Deutsch, C J; Taylor, J S

    1989-01-01

    The pH dependence of the 19F chemical shift has been characterized for a number of fluorine-substituted aniline derivatives. These compounds constitute a new class of 19F nuclear magnetic resonance (NMR) pH indicators, characterized by single 19F resonance lines with sensitivities ranging from 2 to 7 ppm/pH unit near the aniline pKa; total shifts between conjugate acid and base of 5-15 ppm; and pKas ranging from 1 to 7. One compound, N,N-(methyl-2-carboxyisopropyl)-4-fluoroaniline, has a pKa of 6.8 and a sensitivity of 5 ppm/pH unit. This compound displays significant broadening of its 19F resonance near the aniline pKa (6.8), due to a decreased rate of exchange between conjugate acid and base species. Our results are consistent with slow dissociation of an intramolecular hydrogen bond in the zwitterionic species that limits the exchange rate between protonated and unprotonated forms for N,N-(methyl-2-carboxyisopropyl)-4-fluoroaniline. PMID:2720073

  13. Synthetic control and empirical prediction of redox potentials for Co4O4 cubanes over a 1.4 V range: implications for catalyst design and evaluation of high-valent intermediates in water oxidation

    DOE PAGES

    Nguyen, Andy I.; Wang, Jianing; Levine, Daniel S.; ...

    2017-04-07

    The oxo-cobalt cubane unit [Co4O4] is of interest as a homogeneous oxygen-evolution reaction (OER) catalyst, and as a functional mimic of heterogeneous cobalt oxide OER catalysts. The synthesis of several new cubanes allows evaluation of redox potentials for the [Co4O4] cluster, which are highly sensitive to the ligand environment and span a remarkable range of 1.42 V. The [CoIII4O4]4+/[CoIII3CoIVO4]5+ and [CoIII3CoIVO4]5+/[CoIII2CoIV2O4]6+ redox potentials are reliably predicted by the pKas of the ligands. Hydrogen bonding is also shown to significantly raise the redox potentials, by ~500 mV. The potential-pKa correlation is used to evaluate the feasibility of various proposed OER catalyticmore » intermediates, including high-valent Co-oxo species. The synthetic methods and structure–reactivity relationships developed by these studies should better guide the design of new cubane-based OER catalysts.« less

  14. Synthesis, characterization and non-isothermal decomposition kinetic of a new galactochloralose based polymer.

    PubMed

    Kök, Gökhan; Ay, Kadir; Ay, Emriye; Doğan, Fatih; Kaya, Ismet

    2014-01-30

    A glycopolymer, poly(3-O-methacroyl-5,6-O-isopropylidene-1,2-O-(S)-trichloroethylidene-α-d-galactofuranose) (PMIPTEG) was synthesized from the sugar-carrying methacrylate monomer, 3-O-methacroyl-5,6-O-isopropylidene-1,2-O-(S)-trichloroethylidene-α-d-galactofuranose (MIPTEG) via conventional free radical polymerization with AIBN in 1,4-dioxane. The structures of glycomonomer and their polymers were confirmed by UV-vis, FT-IR, (1)H NMR, (13)C NMR, GPC, TG/DTG-DTA, DSC, and SEM techniques. SEM images showed that PMIPTEG had a straight-chain length structure. On the other hand, the thermal decomposition kinetics of polymer were investigated by means of thermogravimetric analysis in dynamic nitrogen atmosphere at different heating rates. The apparent activation energies for thermal decomposition of the PMIPTEG were calculated using the Kissinger, Kim-Park, Tang, Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) and Friedman methods and were found to be 100.15, 104.40, 102.0, 102.2, 103.2 and 99.6 kJ/mol, respectively. The most likely process mechanism related to the thermal decomposition stage of PMIPTEG was determined to be a Dn deceleration type in terms of master plots results.

  15. Preclinical Pharmacology and Toxicology of Intravenous MV-NIS, an Oncolytic Measles Virus Administered With or Without Cyclophosphamide

    PubMed Central

    Myers, RM; Greiner, SM; Harvey, ME; Griesmann, G; Kuffel, MJ; Buhrow, SA; Reid, JM; Federspiel, M; Ames, MM; Dingli, D; Schweikart, K; Welch, A; Dispenzieri, A; Peng, K-W; Russell, SJ

    2009-01-01

    MV-NIS is an oncolytic measles virus encoding the human thyroidal sodium iodide symporter (NIS). Here, we report the results of preclinical pharmacology and toxicology studies conducted in support of our clinical protocol “Phase I Trial of Systemic Administration of Edmonston Strain of Measles Virus, Genetically Engineered to Express NIS, with or without Cyclophosphamide, in Patients with Recurrent or Refractory Multiple Myeloma.” Dose–response studies in the KAS-6/1 myeloma xenograft model demonstrated a minimum effective dose of 4 × 106 TCID50 (tissue culture infectious dose 50)/kg. Toxicity studies in measles-naive squirrel monkeys and measles-susceptible transgenic mice were negative at intravenous doses up to 108 and 4 × 108 TCID50/kg, respectively. Abundant viral mRNA, maximal on day 8, was detected in cheek swabs of squirrel monkeys, more so after pretreatment with cyclophosphamide. On the basis of these data, the safe starting dose of MV-NIS for our clinical protocol was set at 1 – 2 × 104 TCID50/kg (106 TCID50 per patient). PMID:17971816

  16. A molecular phylogenetic evaluation of the spizellomycetales.

    PubMed

    Wakefield, William S; Powell, Martha J; Letcher, Peter M; Barr, Donald J S; Churchill, Perry F; Longcore, Joyce E; Chen, Shu-Fen

    2010-01-01

    Order Spizellomycetales was delineated based on a unique suite of zoospore ultrastructural characters and currently includes five genera and 14 validly published species, all of which have a propensity for soil habitats. We generated DNA sequences from small (SSU), large (LSU) and 5.8S ribosomal subunit genes to assess the monophyly of all genera and species in this order. The 53 cultures analyzed included isolates on which all described species were based, plus other spizellomycetalean cultures. Phylogenetic placement of these chytrids was explored with maximum parsimony and maximum likelihood analyses, both of which yielded comparable topologies. Kochiomyces, Powellomyces and Triparticalcar were monophyletic, while Gaertneriomyces and Spizellomyces were polyphyletic. Isolates, distinct from described species, clustered among each of the five genera, indicating that species diversity in genera is greater than currently recognized. One isolate formed a clade that included no described species, representing a new genus. Zoospore ultrastructural features and architecture seem to be good indicators of phylogenetic relationships, but finer scrutiny of characters such as kinetosome-associated structures (KAS) is needed to understand more clearly the diversity within this order as it is revised.

  17. Progress in the prediction of pKa values in proteins

    SciTech Connect

    Alexov, Emil; Mehler, Ernest L.; Baker, Nathan A.; Baptista, Antonio; Huang, Yong; Milletti, Francesca; Nielsen, Jens E.; Farrell, Damien; Carstensen, Tommy; Olsson, Mats H.; Shen, Jana K.; Warwicker, Jim; Williams, Sarah; Word, J Michael

    2011-12-15

    The pKa-cooperative aims to provide a forum for experimental and theoretical researchers interested in protein pKa values and protein electrostatics in general. The first round of the pKa -cooperative, which challenged computational labs to carry out blind predictions against pKas experimentally determined in the laboratory of Bertrand Garcia-Moreno, was completed and results discussed at the Telluride meeting (July 6-10, 2009). This paper serves as an introduction to the reports submitted by the blind prediction participants that will be published in a special issue of PROTEINS: Structure, Function and Bioinformatics. Here we briefly outline existing approaches for pKa calculations, emphasizing methods that were used by the participants in calculating the blind pKa values in the first round of the cooperative. We then point out some of the difficulties encountered by the participating groups in making their blind predictions, and finally try to provide some insights for future developments aimed at improving the accuracy of pKa calculations.

  18. PHEPS: web-based pH-dependent Protein Electrostatics Server

    PubMed Central

    Kantardjiev, Alexander A.; Atanasov, Boris P.

    2006-01-01

    PHEPS (pH-dependent Protein Electrostatics Server) is a web service for fast prediction and experiment planning support, as well as for correlation and analysis of experimentally obtained results, reflecting charge-dependent phenomena in globular proteins. Its implementation is based on long-term experience (PHEI package) and the need to explain measured physicochemical characteristics at the level of protein atomic structure. The approach is semi-empirical and based on a mean field scheme for description and evaluation of global and local pH-dependent electrostatic properties: protein proton binding; ionic sites proton population; free energy electrostatic term; ionic groups proton affinities (pKa,i) and their Coulomb interaction with whole charge multipole; electrostatic potential of whole molecule at fixed pH and pH-dependent local electrostatic potentials at user-defined set of points. The speed of calculation is based on fast determination of distance-dependent pair charge-charge interactions as empirical three exponential function that covers charge–charge, charge–dipole and dipole–dipole contributions. After atomic coordinates input, all standard parameters are used as defaults to facilitate non-experienced users. Special attention was given to interactive addition of non-polypeptide charges, extra ionizable groups with intrinsic pKas or fixed ions. The output information is given as plain-text, readable by ‘RasMol’, ‘Origin’ and the like. The PHEPS server is accessible at . PMID:16845042

  19. Latvian Waste Management Modelling in View of Environmental Impact Reduction / Latvijas Atkritumu SAIMNIECĪBAS ATTĪSTĪBA un TĀS RADĪTĀS Ietekmes UZ Vidi SAMAZINĀŠANAS MODELĒŠANA

    NASA Astrophysics Data System (ADS)

    Teibe, I.; Bendere, R.; Arina, D.

    2013-12-01

    In the work, the life-cycle assessment approach is applied to the planning of waste management development in a seaside region (Piejūra) using the Waste Management Planning System (WAMPS) program. In Latvia, the measures to be taken for the climate change mitigation are of utmost importance - especially as related to the WM performance, since a disposal of biodegradable waste presents the primary source of GHG emissions. To reduce the amount of such waste is therefore one of the most significant goals in the State WM plan for 2013-2020, whose adoption is the greatest challenge for municipalities. The authors analyse seven models which involve widely employed biomass processing methods, are based on experimental data and intended for minimising the direct disposal of organic mass at the solid waste landfills. The numerical results obtained evidence that the thermal or biotechnological treatment of organic waste substantially reduces the negative environmental impact of WM practices - by up to 6% as compared with the currently existing. Klimata pārmaiņu samazināšanas pasākumi Latvijā atkritumu saimniecības sektorā ir īpaši svarīgi. jo bioloģiski sadalāmo atkritumu apglabāšana ir viens no būtiskākajiem SEG emisiju avotiem valstī. Pētījumā modelēti virkne sadzīves atkritumu apsaimniekošanas modeļi. kas ietver plašāk izmantotās biomasas pārstrādes metodes un samazina tiešu organiskās masas apglabāšanu cieto sadzīves atkritumu poligonos. Atkritumu apsaimniekošanas modeļu radītās vides ietekmes novērtēšanai izmantota WAMPS (Waste Management Planning System) programma, kas balstīta uz atkritumu apsaimniekošanas procesu dzīves cikla novērtējumu vienā no desmit Latvijas atkritumu apsaimniekošanas reģioniem - Piejūra. Iegūtie kvantitatīvie rezultāti norāda. ka organiskās atkritumu masas pārstrāde un stabilizēšana, izmantojot biotehnoloģijas vai termisko pārstrādi, būtiski samazina atkritumu apsaimniekošanas rad

  20. Operative and technological management of super-large united power grids: lessons of major world's blackouts

    NASA Astrophysics Data System (ADS)

    Brinkis, K.; Kreslins, V.; Mutule, A.

    2014-02-01

    Power system (PS) blackouts still persist worldwide, evidencing that the existing protective structures need to be improved. The discussed requirements and criteria to be met for joint synchronous operation of large and super-large united PSs should be based on close co-ordination of operative and technological management of all PSs involved in order to ensure secure and stable electricity supply and minimise or avoid the threat of a total PS blackout. The authors analyse the July 2012 India blackout - the largest power outage in history, which affected over 620 million people, i.e. half of India's population and spread across its 22 states. The analysis is of a general character, being applicable also to similar blackouts that have occurred in Europe and worldwide since 2003. The authors summarise and develop the main principles and methods of operative and technological management aimed at preventing total blackouts in large and super-large PSs. Neskatoties uz sasniegumiem elektroenerģētikas jomā un energosistēmu nepārtrauktu modernizāciju, pasaulē regulāri notiek sabrukumu avārijas. Rakstā apskatīti lielu un superlielu energosistēmu apvienību savstarpējas sinhronas darbības nodrošinājuma prasības un kritēriji, kas pamatojas uz operatīvās un tehnoloģiskās vadības ciešu koordināciju starp energosistēmām. Savstarpējas sinhronas darbības nodrošinājuma prasībām un kritērijiem ir izšķiroša nozīme, lai panāktu elektroapgādes drošumu un stabilitāti katrā energosistēmā, kas darbojas apvienotas energosistēmas sastāvā. Šo prasību un kritēriju ievērošana sekmē totālo avāriju izcelšanās iespēju samazināšanu un to novēršanu. Indijas 2012.gada totālo avāriju un citu analogo avāriju Eiropā un Amerikā analīze un izvērtējums laika posmā no 2003.gada, deva iespēju apkopot un izstrādāt lielu un superlielu energosistēmu operatīvās un tehnoloģiskās vadības principus un metodoloģiju, lai novērstu vai

  1. Testing alternative tectonic models of Palaeotethys in the E Mediterranean region: new U-Pb and Lu-Hf isotopic analyses of detrital zircons from Late Carboniferous and Late Triassic sandstones associated with the Anatolide and Tauride blocks (S Turkey)

    NASA Astrophysics Data System (ADS)

    Ustaömer, Timur; Ayda Ustaömer, Petek; Robertson, Alastair; Gerdes, Axel

    2016-04-01

    Alternative tectonic models of Palaeotethys during Late Palaeozoic-Early Mesozoic time infer: 1. southward subduction beneath the north margin of Gondwana; 2. northward subduction beneath the south margin of Eurasia, or 3. double subduction (northwards and southwards), at least during Late Carboniferous. U-Pb and Lu-Hf isotopic analysis of detrital zircons, extracted from sandstones, can provide strong indications of age and identity of source terranes. Here, we consider the provenance of both Late Carboniferous and Late Triassic sandstones from both relatively allochthonous and relatively autochthonous units that are all spatially associated with the Anatolide and Tauride continental blocks. The relatively allochthonous units are sandstones (3 samples) from the Late Carboniferous Aladaǧ Nappe (Tauride; in the east), the Konya Complex (Anatolide; central area) and the Karaburun Mélange (Tauride-related; in the west). The relatively autochthonous units are Late Triassic sandstones (4 samples) from the Üzümdere Formation, the Kasımlar Formation (both western Taurides) and the Güvercinlik Formation (Karaburun Peninsula-Tauride related; far west). The Late Carboniferous sandstones from the three relatively allochthonous units are dominated by Precambrian zircon populations, the age distribution of which suggests derivation from two contrasting source regions: First, a NE African-type source (i.e. Saharan craton) for the sandstones of the Konya Mélange and the Aladaǧ Nappe because these sediments have prominent zircon populations dated at 0.5-0.7, 0.8 and 0.9-1.1 Ga. Palaeozoic zircons are minimal in the sandstones of the Aladaǧ Nappe and the Konya Complex (3 and 5% of the whole data, respectively) and are confined to Cambrian to Ordovician. Secondly, a contrasting NW African-type source is inferred for sandstone from the Karaburun Mélange because of the marked absence of Tonian-Stenian zircons and the predominance of ~2 Ga zircons over ~2.5 Ga zircons. In

  2. Obtaining a Well-Aligned ZnO Nanotube Array Using the Hydrothermal Growth Method / Labi Sakārtotu Zno Nanocauruļu Kopu Iegūšana, Izmantojot Hidrotermālo Metodi

    NASA Astrophysics Data System (ADS)

    Krasovska, M.; Gerbreders, V.; Paskevics, V.; Ogurcovs, A.; Mihailova, I.

    2015-10-01

    Optimal growing parameters have been found using the hydrothermal method to obtain well-aligned vertical ZnO nanorod and nanotube arrays. The influence of different growing factors (such as temperature, growing solution concentration, method of obtaining seed layer and condition) on nanotube morphology and size is described in the paper. Well-structured ZnO nanotubes have been obtained by using a selfselective etching method with lowering temperatures of growth during the hydrothermal process. It is shown that the optical properties of the nanostructure arrays obtained are sensitive to the medium in which they are placed, which is why they can be used as sensors for pure substance detection and in different solutions for impurity determination. Dotajā darbā tika noteikti optimāli parametri labi sakārtotu ZnO nanocaurulīšu kopu iegūšanai, izmantojot hidrotermālo metodi ar temperatūras pazemināšanu, jeb t.s. selektīvu pa\\vskodināšanas metodi (self-selective etching), ir uzsvērtas šās metodes priekšrocības salīdzinājumā ar ķīmiskās kodināšanas metodi, kā arī tika aprakstīta dažādu augšanas faktora (tādu, ka darba šķīduma koncentrācija, augšanas temperatūra un laiks, iedīgļu slāņa iegūšanas veids un iegūšanas parametri) ietekme uz iegūtu nanostraktūra morfoloģiju. Tika konstatēts, ka noteicošu lomu ZnO nanocaurulīšu audzēšanas procesā spēlē iedīgļu slāņa graudu izmēri, kas savā staipā nosaka augošu nanostieņu izmērus un to tendenci pie pa\\vskodināšanas. Rentgenogrannnas parāda, ka iegūtām pie noteiktiem parametriem ZnO nanostruktūrām piemīt augsta kristāliskuma pakāpe un sakārtotība vertikālā virzienā. Optiskie mērījumi parāda, ka ZnO nanocauralītes ir jutīgas gan pret tīrām vielām (ūdens, spirts), gan pret dažādiem šķīdumiem, kas ļauj izmantot tos kā pie­jaukumu sensora. Salīdzinājumā ar ZnO nanostieņiem caurulīšu jūtība pieaug, jo pieaug nanostrakt

  3. Assessment of Wind Shear and Wind Energy Potential in the Baltic Sea Region of Latvia

    NASA Astrophysics Data System (ADS)

    Bezrukovs, V.; Bezrukovs, Vl.; Zacepins, A.; Komashilovs, V.

    2015-04-01

    The paper is devoted to the investigation into the wind energy potential based on long-term observations of the wind speed and energy density fluctuations at heights from 10 to 160 m on the Baltic Sea coast of Latvia. During the observations (2004 - 2013), the wind speed and direction values were measured, and the statistical database was accumulated using a LOGGER 9200 Symphonie measuring systems mounted on 60 m masts - one on the western coast and another on the north-east of Latvia. From June 2011 to May 2012, these measurements were complemented with the data for the heights from 40 to 160 m obtained by means of a ZephIR lidar and with the metrological data provided by "Latvian Environment, Geology and Meteorology Centre" for the same period. The graphs of seasonal fluctuations in the wind speed were obtained for the heights up to 160 m by measurements over the period of 2007 - 2013. The results of the research on the wind speed distribution up to 200 m are promising for evaluation of the wind energy potential of Latvia and will be helpful in assessment of prospective sites for construction of WPPs. Zinātniskais raksts ir veltīts pētījumam par vēja enerģijas potenciālu Latvijas teritorijā, Baltijas jūras piekrastē, balstoties uz ilgtermiņa vēja ātruma un vēja enerģijas blīvuma svārstību novērojumiem no 10 līdz 160 metriem augstumā. Vēja ātruma un vēja virziena mērījumu dati tika iegūti un apkopoti statistiskajā datubāzē laika periodā no 2004 līdz 2013. gadam, izmantojot mērīšanas sistēmu LOGGER 9200 Symphonie, kas bija ierīkotā uz 60 metru augsta masta - viena rietumu piekrastē un otra Latvijas ziemeļu-austrumos. No 2011. gada jūnija līdz 2012. gada maijam mērījumu datubāze tika papildināta ar datiem, kas tika iegūti ar lidaruZephIR augstumos no 40 līdz 160 metriem, un datiem no "Latvijas Vides, ģeoloģijas un meteoroloģijas centra" tam pašam laika periodam. Analizējot mērījumus 2007. g.-2013. g., grafiki ar

  4. Development of Dynamically Optimized Wireless Transmission System for Wireless Sensor Networks in Highrise Apartment Building Heating Systems / Optimizētas Dinamiskās Bezvadu Sensoru Tīklu Pārraides Risinājuma Izstrāde Daudzstāvu Ēku Apkures Sistēmas Parametru Izgūšanai Un Vadībai

    NASA Astrophysics Data System (ADS)

    Isakovs, V.; Kondratjevs, K.; Kunicina, N.; Freliha, B.; Zabasta, A.

    2015-08-01

    Smart meters will be at the centre of the integrated solutions, including interaction with other networks in the next decade. The developed solution for multi-apartment building ventilation and heating parameter monitoring aims to increase energy efficiency and optimal control of the existing system. Dynamic control of heat and ventilation systems, heat loss detection, calculation and mitigation, and individual heat energy accounting are difficult tasks to accomplish. This article deals with the data transmission system using battery powered ISM band radio transmitters. The temperature measurement sensors with cumulative temperature reading are used as sensor part for this solution. The offered approach to monitoring system is used for overall building and individual apartment monitoring. Data coding and antenna designs are explained for this particular application. Daudzstāvu ēkas, kuras nav sākotnēji plānotas integrācijai ar ēku vadības sistēmām, rada kompleksu problemātisko vidi modernizācijai. Vadu sensoru sistēmu uzstādīšana šādās ēkās kļūst nepraktiska vai pat neiespējama. Šī iemesla dēļ ir nepieciešamas efektīvas bezvadu sensoru sistēmas, kas spētu nodrošināt mērījumu nogādi, ņemot vērā daudzstāvu ēku specifiku. Rakstā tiek piedāvāts bezvadu sensoru tīkla risinājums efektīvai datu pārraidei siltumapgādes sistēmas parametru izgūšanai. Tiek izstrādāta un aprobēta specializētā virziena antena efektīvai radio telegrammu savākšanai no dzīvokļiem, nogādājot mērījumus datu koncentratoros. Ziņojumu telegrammu efektīvai pārraidei tiek piedāvāta datu kodēšanas kumulatīvā metode. Piedāvātais risinājums pielietojams gan jaunām, gan esošām ēkām. Izgūtie dati ir pielietojami siltuma apgādes sistēmas uzraudzībai, regulēšanai, kā arī individuālā siltuma patēriņa tarifikācijai.

  5. Multi-Objective Optimization of Transmission Lines / Elektropārvades Līnijas Daudzkriteriālā Optimizācija

    NASA Astrophysics Data System (ADS)

    Berjozkina, S.; Sauhats, A.; Neimane, V.

    2013-10-01

    Introduction of new advanced electrical connections into a transmission grid reduces the capacity of existing overhead lines (OHLs). At the same time, designing & building of new OHLs and substations involves considerable technical, environmental and economical problems. The authors propose a concept of the multi-objective optimization for selection of transmission line routes, towers (their type, placement and geometry), of conductors, insulators, dampers, earthing and lightning protection systems, span lengths, etc.. The optimization is organized in five stages. At the first and second stages a search for optimum solutions is performed along with determination of the main impacting factors. The next two stages present a two-objective optimization based on Pareto's approach. At the last stage (exemplified by a case study), the probability of the restriction removal conditions is assessed, and preventive measures are identified. The presented approach uses a real line design and is intended for minimizing the total invested capital and maximizing the net present value. In the framework of this approach 20 alternatives have been elaborated, which can successfully be applied in the cases described in the paper. Elektropārvades tīklam rodas nepieciešamība pēc jauniem elektriskajiem pieslēgumiem, kas noved pie esošo gaisvadu līniju jaudas nepietiekamības. Viens no iespējamajiem pastāvošās problēmas risinājumiem ir jaunu gaisvadu līniju un apakšstacijas būvniecība. Gaisvadu līniju projektēšana ir saistīta ar ievērojamām tehniskām, vides un ekonomiskām problēmām. Darbā aprakstīta elektropārvades līnijas optimālās trases izvēles daudzkritēriju optimizācijas koncepcija, ieskaitot balstu tipa, balstu izvietojuma koordināšu, balstu ģeometrijas, vadu tipu un parametru, izolatoru tipu, vibroslāpētāju tipu, zibensaizsardzības un zemēšanas sistēmu, kā arī laidumu garumu izvēles optimizāciju. Optimizācijas uzdevums tiek organiz

  6. Heterologous production of kasugamycin, an aminoglycoside antibiotic from Streptomyces kasugaensis, in Streptomyces lividans and Rhodococcus erythropolis L-88 by constitutive expression of the biosynthetic gene cluster.

    PubMed

    Kasuga, Kano; Sasaki, Akira; Matsuo, Takashi; Yamamoto, Chika; Minato, Yuiko; Kuwahara, Naoya; Fujii, Chikako; Kobayashi, Masayuki; Agematu, Hitosi; Tamura, Tomohiro; Komatsu, Mamoru; Ishikawa, Jun; Ikeda, Haruo; Kojima, Ikuo

    2017-02-27

    Kasugamycin (KSM), an aminoglycoside antibiotic isolated from Streptomyces kasugaensis cultures, has been used against rice blast disease for more than 50 years. We cloned the KSM biosynthetic gene (KBG) cluster from S. kasugaensis MB273-C4 and constructed three KBG cassettes (i.e., cassettes I-III) to enable heterologous production of KSM in many actinomycetes by constitutive expression of KBGs. Cassette I comprised all putative transcriptional units in the cluster, but it was placed under the control of the P neo promoter from Tn5. It was not maintained stably in Streptomyces lividans and did not transform Rhodococcus erythropolis. Cassette II retained the original arrangement of KBGs, except that the promoter of kasT, the specific activator gene for KBG, was replaced with P rpsJ , the constitutive promoter of rpsJ from Streptomyces avermitilis. To enhance the intracellular concentration of myo-inositol, an expression cassette of ino1 encoding the inositol-1-phosphate synthase from S. avermitilis was inserted into cassette II to generate cassette III. These two cassettes showed stable maintenance in S. lividans and R. erythropolis to produce KSM. Particularly, the transformants of S. lividans induced KSM production up to the same levels as those produced by S. kasugaensis. Furthermore, cassette III induced more KSM accumulation than cassette II in R. erythropolis, suggesting an exogenous supply of myo-inositol by the ino1 expression in the host. Cassettes II and III appear to be useful for heterologous KSM production in actinomycetes. Rhodococcus exhibiting a spherical form in liquid cultivation is also a promising heterologous host for antibiotic fermentation.

  7. Calculating Free Energy Changes in Continuum Solvation Models

    DOE PAGES

    Ho, Junming; Ertem, Mehmed Z.

    2016-02-27

    We recently showed for a large dataset of pKas and reduction potentials that free energies calculated directly within the SMD continuum model compares very well with corresponding thermodynamic cycle calculations in both aqueous and organic solvents (Phys. Chem. Chem. Phys. 2015, 17, 2859). In this paper, we significantly expand the scope of our study to examine the suitability of this approach for the calculation of general solution phase kinetics and thermodynamics, in conjunction with several commonly used solvation models (SMDM062X, SMD-HF, CPCM-UAKS, and CPCM-UAHF) for a broad range of systems and reaction types. This includes cluster-continuum schemes for pKa calculations,more » as well as various neutral, radical and ionic reactions such as enolization, cycloaddition, hydrogen and chlorine atom transfer, and bimolecular SN2 and E2 reactions. On the basis of this benchmarking study, we conclude that the accuracies of both approaches are generally very similar – the mean errors for Gibbs free energy changes of neutral and ionic reactions are approximately 5 kJ mol-1 and 25 kJ mol-1 respectively. In systems where there are significant structural changes due to solvation, as is the case for certain ionic transition states and amino acids, the direct approach generally afford free energy changes that are in better agreement with experiment. The results indicate that when appropriate combinations of electronic structure methods are employed, the direct approach provides a reliable alternative to the thermodynamic cycle calculations of solution phase kinetics and thermodynamics across a broad range of organic reactions.« less

  8. Hemofagocitinė limfohistiocitozė: literatūros apžvalga

    PubMed Central

    Bereikienė, Simona; Rascon, Jelena

    2017-01-01

    Hemofagocitinė limfohistiocitozė – tai sindromas, besivystantis dėl sutrikusios imuninio atsako aktyvacijos ir slopinimo pusiausvyros. Išskiriama pirminė (genetinė arba šeiminė) sindromo forma, nulemta genų, dalyvaujančių imuninių ląstelių sąveikoje, mutacijų; ir antrinė (sporadinė) forma, besivystanti dėl infekcijos, navikinio, autoimuninio proceso ar metabolinių sutrikimų. Antrinės hemofagocitinės limfohistiocitozės genetinis pagrindas kol kas nežinomas. Pirminei ir antrinei formoms būdingas toks pats specifinis hiperuždegiminių reakcijų bei klinikinių simptomų kompleksas, kuriuo grindžiama patologijos diagnostika. Tačiau pirminės ir antrinės formų atskyrimas dažnai tampa iššūkiu dėl patologijos retumo, plataus klinikinių požymių spektro, dėl riboto specifinių testų prieinamumo ir, svarbiausia, gydymo taktikos ypatumų. Etiopatogenetinis pirminės formos gydymas yra skubi alogeninė kraujodaros kamieninių ląstelių transplantacija, be kurios išeitis neišvengiamai fatali. Antrinės formos gydymas priklauso nuo klinikinės išraiškos ir ją sukėlusios infekcijos pobūdžio. Labai svarbi laiku atlikta diagnostika norint kuo skubiau pradėti tinkamą gydymą bei pagerinti išgyvenamumą. Hemofagocitinės limfohistiocitozės gydymą komplikuoja didelis su gydymu susijęs mirtingumo dažnis bei ligos polinkis recidyvuoti. PMID:28630593

  9. Attributing the influence of urban and industrial nitrous oxide emission sources on atmospheric concentrations measured at surface monitoring stations. A case study from Central Europe (Poland).

    NASA Astrophysics Data System (ADS)

    Galkowski, M.; Gerbig, C.; Nęcki, J. M.; Chmura, Ł.; Rozanski, K.

    2015-12-01

    A regional study of the source-receptor relationship is analysed between the strong anthropogenic sources of nitrous oxide and the concentrations of this gas measured at two surface stations of distinct characteristics: urban (represented by Kraków station - KRK) and clean environment (high-mountain station Kasprowy Wierch - KAS). A long-term records of N2O mixing ratios at both stations (2012-2014) provide the necessary statistics and temporal patterns. To achieve that purpose, a modeling framework has been established that utilizes the Stochastic Time-Inverted Lagrangian Model (STILT), driven by the meteorological fields from the Integrated Forecasting System and coupled to the IER hourly emission database.. The framework allowed spatial source apportionment of the nitrous oxide loads measured at both stations. The influences of the most important regional sources of N2O have been analyzed, including Krakow agglomeration (waste, transport and power production) and chemical plant (nitric acid and caprolactam production), located ca. 100 km east of Krakow. The relative enhancement of these sources were analyzed against the reference scenario (all available European emission sources) and against the regional total. The results have shown significant differences in the station characteristics, with very small enhancements of N2O concentrations predicted for Kasprowy Wierch (maximum 2 ppb). For Kraków, the predicted concentrations were higher (close to 2 ppb monthly median). Influence of the sources located in Małopolska have been shown to be in the range of 20% - 80% with a temporal variability on daily and seasonal scales. The predictions of the model were validated against in-situ observations performed at both stations, pointing to possible misattribution of the local sources in Kraków.

  10. Cap-binding activity of an eIF4E homolog from Leishmania

    PubMed Central

    YOFFE, YAEL; ZUBEREK, JOANNA; LEWDOROWICZ, MAGDALENA; ZEIRA, ZIV; KEASAR, CHEN; ORR-DAHAN, IRIT; JANKOWSKA-ANYSZKA, MARZENA; STEPINSKI, JANUSZ; DARZYNKIEWICZ, EDWARD; SHAPIRA, MICHAL

    2004-01-01

    All eukaryotic mRNAs possess a 5′-cap (m7GpppN) that is recognized by a family of cap-binding proteins. These participate in various processes, such as RNA transport and stabilization, as well as in assembly of the translation initiation complex. The 5′-cap of trypanosomatids is complex; in addition to 7-methyl guanosine, it includes unique modifications on the first four transcribed nucleotides, and is thus denoted cap-4. Here we analyze a cap-binding protein of Leishmania, in an attempt to understand the structural features that promote its binding to this unusual cap. LeishIF4E-1, a homolog of eIF4E, contains the conserved cap-binding pocket, similar to its mouse counterpart. The mouse eIF4E has a higher Kas for all cap analogs tested, as compared with LeishIF4E-1. However, whereas the mouse eIF4E shows a fivefold higher affinity for m7GTP than for a chemically synthesized cap-4 structure, LeishIF4E-1 shows similar affinities for both ligands. A sequence alignment shows that LeishIF4E-1 lacks the region that parallels the C terminus in the murine eIF4E. Truncation of this region in the mouse protein reduces the difference that is observed between its binding to m7GTP and cap-4, prior to this deletion. We hypothesize that variations in the structure of LeishIF4E-1, possibly also the absence of a region that is homologous to the C terminus of the mouse protein, promote its ability to interact with the cap-4 structure. LeishIF4E-1 is distributed in the cytoplasm, but its function is not clear yet, because it cannot substitute the mammalian eIF4E in a rabbit reticulocyte in vitro translation system. PMID:15388875

  11. Bohr effect of hemoglobins: Accounting for differences in magnitude.

    PubMed

    Okonjo, Kehinde O

    2015-09-07

    The basis of the difference in the Bohr effect of various hemoglobins has remained enigmatic for decades. Fourteen amino acid residues, identical in pairs and located at specific 'Bohr group positions' in human hemoglobin, are implicated in the Bohr effect. All 14 are present in mouse, 11 in dog, eight in pigeon and 13 in guinea pig hemoglobin. The Bohr data for human and mouse hemoglobin are identical: the 14 Bohr groups appear at identical positions in both molecules. The dog data are different from the human because three Bohr group positions are occupied by non-ionizable groups in dog hemoglobin; the pigeon data are vastly different from the human because six Bohr group positions are occupied by non-ionizable groups in pigeon hemoglobin. The guinea pig data are quite complex. Quantitative analyses showed that only the pigeon data could be fitted with the Wyman equation for the Bohr effect. We demonstrate that, apart from guinea pig hemoglobin, the difference between the Bohr effect of each of the other hemoglobins and of pigeon hemoglobin can be accounted for quantitatively on the basis of the occupation of some of their Bohr group positions by non-ionizable groups in pigeon hemoglobin. We attribute the anomalous guinea pig result to a new salt-bridge formed in its R2 quaternary structure between the terminal NH3(+) group of one β-chain and the COO(-) terminal group of the partner β-chain in the same molecule. The pKas of this NH3(+) group are 6.33 in the R2 and 4.59 in the T state. Copyright © 2015 Elsevier Ltd. All rights reserved.

  12. Redox-linked proton translocation in cytochrome oxidase: the importance of gating electron flow. The effects of slip in a model transducer.

    PubMed Central

    Blair, D F; Gelles, J; Chan, S I

    1986-01-01

    In at least one component of the mitochondrial respiratory chain, cytochrome c oxidase, exothermic electron transfer reactions are used to drive vectorial proton transport against an electrochemical hydrogen ion gradient across the mitochondrial inner membrane. The role of the gating of electrons (the regulation of the rates of electron transfer into and out of the proton transport site) in this coupling between electron transfer and proton pumping has been explored. The approach involves the solution of the steady-state rate equations pertinent to proton pump models which include, to various degrees, the uncoupled (i.e., not linked to proton pumping) electron transfer processes which are likely to occur in any real electron transfer-driven proton pump. This analysis furnishes a quantitative framework for examining the effects of variations in proton binding site pKas and metal center reduction potentials, the relationship between energy conservation efficiency and turnover rate, the conditions for maximum power output or minimum heat production, and required efficiency of the gating of electrons. Some novel conclusions emerge from the analysis, including: An efficient electron transfer-driven proton pump need not exhibit a pH-dependent reduction potential; Very efficient gating of electrons is required for efficient electron transfer driven proton pumping, especially when a reasonable correlation of electron transfer rate and electron transfer exoergonicity is assumed; and A consideration of the importance and possible mechanisms of the gating of electrons suggests that efficient proton pumping by CuA in cytochrome oxidase could, in principle, take place with structural changes confined to the immediate vicinity of the copper ion, while proton pumping by Fea would probably require conformational coupling between the iron and more remote structures in the enzyme. The conclusions are discussed with reference to proton pumping by cytochrome c oxidase, and some

  13. Solvation of copper(II) sulfate in binary water/N,N-dimethylformamide mixtures: from the solution to the gas phase.

    PubMed

    Tsierkezos, Nikos G; Roithova, Jana; Schröder, Detlef; Molinou, Ioanna E; Schwarz, Helmut

    2008-04-10

    The solvation of copper(II) sulfate in binary mixtures of water and N,N-dimethylformamide (DMF) is studied by a combined approach using electrochemical studies in solution and a mass spectrometric assay of the solvated ions formed from these solutions upon electrospray ionization (ESI). In the condensed phase, the limiting transference numbers (t(+/-)(o)) and the apparent ion association constants (K(A)'s) of CuSO(4) have been determined in water/DMF solutions at 20 degrees C. The t(+)(o) values decrease with increasing DMF content, demonstrating a gradual solvation of Cu(2+) by DMF molecules. The association constants indicate that aggregation becomes more pronounced as the DMF content increases. In order to achieve complementary insight, the intrinsic interactions among the ions and solvent molecules are investigated in gas-phase experiments of the CuSO(4)/water/DMF system using ESI mass spectrometry. Under the conditions used, the dications [Cu(DMF)(n)](2+) (n = 3-6), [Cu(2)(DMF)(n)SO(4)](2+) (n = 2-7), and [Cu(3)(DMF)(n)(SO(4))(2)](2+) (n = 2-7), and the monocations [Cu(OH)(DMF)(n)](+), [Cu(DMF)(n)(HSO(4))](+) (both, n = 1-3), and [Cu(DMF)(n)](+) (n = 1, 2), are formed as the leading copper-containing cations. Likewise, polynuclear copper clusters observed in the anion ESI spectra support partial aggregation occurring in solution. The gas-phase studies clearly support the conclusions that (i) DMF is a highly preferred ligand for CuII in comparison to water and that (ii) DMF supports ion association for which the mass spectrometric data suggest the formation of polynuclear copper clusters.

  14. Development of Technologies for Natural Gas and Biogas Utilization in Transport / Apskats Par Transporta SEKTORĀ IZMANTOJAMĀM DABASGĀZES un BIOGĀZES TEHNOLOĢIJĀM

    NASA Astrophysics Data System (ADS)

    Gelfgat, Y.; Smigins, R.

    2013-12-01

    Popularity of methane-containing gaseous fuels has slowly been growing since their appearance, especially in the last decades. Occasional non-availability of liquid fossil fuels, the necessity to reduce the transportation costs and to improve the air quality are the basic factors which stimulated development of gas utilization technologies - from accumulation, compression and deflation of gas to its usage in internal combustion engines. Since then different solutions have been offered, and the authors are reviewing them - from the first use of natural gas to nowadays. Metāna saturošo gāzu popularitāte kopš to atklāšanas ir pakāpeniski augusi, jo īpaši pēdējās desmitgadēs. Šķidro fosilo degvielu ierobežotā pieejamība dažādos laika periodos, transporta izdevumu izmaksu samazināšana, nepieciešamība uzlabot gaisa kvalitāti - tie ir pamatfaktori, kas sekmējuši gāzes izmantošanas tehnoloģiju attīstību, sākot no gāzes uzkrāšanas, kompresijas un izplūdes sistēmām, un beidzot ar to izmantošanu iekšdedzes motoru darbināšanai. Šajā laikā ir parādījušies dažādi šo tehnoloģiju risinājumi, un dotais raksts sniedz pārskatu par tiem, sākot no pirmās dabasgāzes izmantošanas līdz pat mūsdienām.

  15. Natural Variation of Cold Deacclimation Correlates with Variation of Cold-Acclimation of the Plastid Antioxidant System in Arabidopsis thaliana Accessions

    PubMed Central

    Juszczak, Ilona; Cvetkovic, Jelena; Zuther, Ellen; Hincha, Dirk K.; Baier, Margarete

    2016-01-01

    Temperature variations impact on the balance between photosynthetic electron transport and electron-consuming assimilation reactions and transiently increase generation of reactive oxygen species (ROS). Previous studies demonstrated that the expression of C-repeat binding factors (CBFs), which activate cold acclimation reactions, respond to chloroplast ROS signals and that cold deacclimation is partly halted for days after the transfer of acclimated plants to optimal growth conditions in four Arabidopsis accessions from cold-continental habitats. We hypothesized that these accessions differ from others in the regulation of the plastid antioxidant system (PAS). In the present study, we compared the expression intensity of the 12 most prominent PAS genes for peroxidases, superoxide dismutase and low molecular weight antioxidant regenerating enzymes in 10 Arabidopsis accessions with regulation of CBF and COR (cold regulated genes) transcript levels and cold-regulated metabolite levels prior to cold, after 2 week long cold acclimation and during the first 3 days of deacclimation. In the accessions with prolonged activation of cold responses, by trend, weaker induction of various cold-inducible PAS genes and stronger decreases in the expression of negatively cold-regulated PAS genes were observed. Low PAS gene expression delayed the post-cold decrease in H2O2 levels after transfer of the plants from cold to optimal growth conditions. We conclude that weaker expression of various PAS genes in the cold is an adapted strategy of the Arabidopsis accessions N14, N13, Ms-0, and Kas-1 to avoid full inactivation of cold-responses in the first days after the end of the cold period. PMID:27014325

  16. 14 kA HTS Current Leads with one 4.8 K Helium Stream for the Prototype Test Facility at GSI

    NASA Astrophysics Data System (ADS)

    Raach, Henning; Schroeder, Claus H.; Floch, Eric; Bleile, Alexander; Schnizer, Pierre; Andersen, Torben P.

    The key part of the international FAIR project in Darmstadt, Germany, is the synchrotron SIS100, for which superconducting mag- nets are employed. For the First of Series Dipole a pair of HTS current leads with a nominal current of 14 kA DC were specified, manufactured and successfully tested. The motivation for these current leads was a high operation current and the liquefaction limit of 1 g/s of the cooling plant. In the design it has to be taken into account that per lead only one helium stream is available for the entirely inner cooling. For I=0 (8 kA DC) only 0.25 g/s/lead (0.38) were necessary to be compared to 0.365 (0.51) specified. Slow ramping with 50 A/s up to 17 kA was accomplished. Triangular cycles with 27 kA/s up to 14 kA were achieved. The current leads withstood the test voltage of 3 kV between two leads and between lead and ground. The one stream helium flow is regulated by the temperature at the warm end of the HTS to be 50 K. The reliability of the first pair, especially of the cold terminal, is a clear go for the series of HTS current leads needed for the Series Test Facility, the String Test and the SIS100 ring. There is a separate 50 K helium gas supply which allows a significant reduction of cooling requirements. These 19 pairs in total shall have a common design which will be slightly different to that of the first pair for the Prototype Test Facility.

  17. The Effect of Mutation of Carboxyl Side-Chain Amino Acids Near the Heme on the Midpoint Potentials and Ligand Binding Constants of Nitrophorin 2 and Its NO, Histamine and Imidazole Complexes

    PubMed Central

    Berry, Robert E.; Shokhirev, Maxim N.; Ho, Arthur Y. W.; Yang, Fei; Shokhireva, Tatiana K.; Zhang, Hongjun; Weichsel, Andrzej; Montfort, William R.; Walker, F. Ann

    2009-01-01

    Nitrophorins (NPs) are a group of NO-carrying heme proteins found in the saliva of a bloodsucking insect from tropical Central and South America, Rhodnius prolixus, the “kissing bug”. NO is kept stable for long periods of time by binding it as an axial ligand to a ferriheme center. The fact that the nitrophorins are stabilized as FeIII-NO proteins is a unique property, for most heme proteins are readily autoreduced by excess NO, and bind NO to the Fe(II) heme irreversibly (Kds in the pM range). In contrast, the nitrophorins, as Fe(III) heme centers, have Kds in the μM to nM range, and thus allow NO to dissociate upon dilution following injection into the tissues of the victim. This NO can cause vasodilation, and thereby allow more blood to be transported to the site of the wound. We have prepared thirteen site-directed mutants of three major nitrophorins, NP2, NP1 and NP4, to investigate the stabilization of the ferric–NO heme center and preservation of reversible binding that facilitates these proteins’ NO storage, transport and release functions. Of the mutations in which Glu and/or Asp were replaced by Ala, most of these carboxyls show a significant role stabilizing FeIII-NO over FeII-NO, with buried E53 of NP2 or E55 of NP1 and NP4 being the most important, and partially buried D29 of NP2 or D30 of NP4 being second in importance. The pKas of the carboxyl groups studied vary significantly, but all are largely deprotonated at pH 7.5 except E124. PMID:19175316

  18. Effects of surface chemistry and size on iron oxide nanoparticle delivery of oligonucleotides

    NASA Astrophysics Data System (ADS)

    Shen, Christopher

    The discovery of RNA interference and the increasing understanding of disease genetics have created a new class of potential therapeutics based on oligonucleotides. This therapeutic class includes antisense molecules, small interfering RNA (siRNA), and microRNA modulators such as antagomirs (antisense directed against microRNA) and microRNA mimics, all of which function by altering gene expression at the translational level. While these molecules have the promise of treating a host of diseases from neurological disorders to cancer, a major hurdle is their inability to enter cells on their own, where they may render therapeutic effect. Nanotechnology is the engineering of materials at the nanometer scale and has gained significant interest for nucleic acid delivery due to its biologically relevant length-scale and amenability to multifunctionality. While a number of nanoparticle vehicles have shown promise for oligonucleotide delivery, there remains a lack of understanding of how nanoparticle coating and size affect these delivery processes. This dissertation seeks to elucidate some of these factors by evaluating oligonucleotide delivery efficiencies of a panel of iron oxide nanoparticles with varying cationic coatings and sizes. A panel of uniformly-sized nanoparticles was prepared with surface coatings comprised of various amine groups representing high and low pKas. A separate panel of nanoparticles with sizes of 40, 80, 150, and 200 nm but with the same cationic coating was also prepared. Results indicated that both nanoparticle surface coating and nanoparticle hydrodynamic size affect transfection efficiency. Specific particle coatings and sizes were identified that gave superior performance. The intracellular fate of iron oxide nanoparticles was also tracked by electron microscopy and suggests that they function via the proton sponge effect. The research presented in this dissertation may aid in the rational design of improved nanoparticle delivery vectors for

  19. Molecular mechanisms for generating transmembrane proton gradients.

    PubMed

    Gunner, M R; Amin, Muhamed; Zhu, Xuyu; Lu, Jianxun

    2013-01-01

    Membrane proteins use the energy of light or high energy substrates to build a transmembrane proton gradient through a series of reactions leading to proton release into the lower pH compartment (P-side) and proton uptake from the higher pH compartment (N-side). This review considers how the proton affinity of the substrates, cofactors and amino acids are modified in four proteins to drive proton transfers. Bacterial reaction centers (RCs) and photosystem II (PSII) carry out redox chemistry with the species to be oxidized on the P-side while reduction occurs on the N-side of the membrane. Terminal redox cofactors are used which have pKas that are strongly dependent on their redox state, so that protons are lost on oxidation and gained on reduction. Bacteriorhodopsin is a true proton pump. Light activation triggers trans to cis isomerization of a bound retinal. Strong electrostatic interactions within clusters of amino acids are modified by the conformational changes initiated by retinal motion leading to changes in proton affinity, driving transmembrane proton transfer. Cytochrome c oxidase (CcO) catalyzes the reduction of O2 to water. The protons needed for chemistry are bound from the N-side. The reduction chemistry also drives proton pumping from N- to P-side. Overall, in CcO the uptake of 4 electrons to reduce O2 transports 8 charges across the membrane, with each reduction fully coupled to removal of two protons from the N-side, the delivery of one for chemistry and transport of the other to the P-side.

  20. Homology modeling and docking studies of FabH (β-ketoacyl-ACP synthase III) enzyme involved in type II fatty acid biosynthesis of Chlorella variabilis: a potential algal feedstock for biofuel production.

    PubMed

    Misra, Namrata; Patra, Mahesh Chandra; Panda, Prasanna Kumar; Sukla, Lala Bihari; Mishra, Barada Kanta

    2013-03-01

    The concept of using microalgae as an alternative renewable source of biofuel has gained much importance in recent years. However, its commercial feasibility is still an area of concern for researchers. Unraveling the fatty acid metabolic pathway and understanding structural features of various key enzymes regulating the process will provide valuable insights to target microalgae for augmented oil content. FabH (β-ketoacyl-acyl carrier protein synthase; KAS III) is a condensing enzyme catalyzing the initial elongation step of type II fatty acid biosynthetic process and acyl carrier protein (ACP) facilitates the shuttling of the fatty acyl intermediates to the active site of the respective enzymes in the pathway. In the present study, a reliable three-dimensional structure of FabH from Chlorella variabilis, an oleaginous green microalga was modeled and subsequently the key residues involved in substrate binding were determined by employing protein-protein docking and molecular dynamics (MD) simulation protocols. The FabH-ACP complex having the lowest docking energy score showed the binding of ACP to the electropositive FabH surface with strong hydrogen bond interactions. The MD simulation results indicated that the substrate-complexed FabH adopted a more stable conformation than the free enzyme. Further, the FabH structure retained its stability throughout the simulation although noticeable displacements were observed in the loop regions. Molecular simulation studies suggested the importance of crucial hydrogen bonding of the conserved Arg(91) of FabH with Glu(53) and Asp(56) of ACP for exhibiting high affinity between the enzyme and substrate. The molecular modeling results are consistent with available experimental results on the flexibility of FabH and the present study provides first in silico insights into the structural and dynamical aspect of catalytic mechanism of FabH, which could be used for further site-specific mutagenic experiments to develop

  1. Redox chemistry of selenenic acids and the insight it brings on transition state geometry in the reactions of peroxyl radicals.

    PubMed

    Zielinski, Zosia; Presseau, Nathalie; Amorati, Riccardo; Valgimigli, Luca; Pratt, Derek A

    2014-01-29

    The redox chemistry of selenenic acids has been explored for the first time using a persistent selenenic acid, 9-triptyceneselenenic acid (RSeOH), and the results have been compared with those we recently obtained with its lighter chalcogen analogue, 9-triptycenesulfenic acid (RSOH). Specifically, the selenenyl radical was characterized by EPR spectroscopy and equilibrated with a phenoxyl radical of known stability in order to determine the O-H bond dissociation enthalpy of RSeOH (80.9 ± 0.8 kcal/mol): ca. 9 kcal/mol stronger than in RSOH. Kinetic measurements of the reactions of RSeOH with peroxyl radicals demonstrate that it readily undergoes H-atom transfer reactions (e.g., k = 1.7 × 10(5) M(-1) s(-1) in PhCl), which are subject to kinetic solvent effects and kinetic isotope effects similar to RSOH and other good H-atom donors. Interestingly, the rate constants for these reactions are only 18- and 5-fold smaller than those measured for RSOH in PhCl and CH3CN, respectively, despite being 9 kcal/mol less exothermic for RSeOH. IR spectroscopic studies demonstrate that RSeOH is less H-bond acidic than RSOH, accounting for these solvent effects and enabling estimates of the pKas in RSeOH and RSOH of ca. 15 and 10, respectively. Calculations suggest that the TS structures for these reactions have significant charge transfer between the chalcogen atom and the internal oxygen atom of the peroxyl radical, which is nominally better for the more polarizable selenenic acid. The higher than expected reactivity of RSeOH toward peroxyl radicals is the strongest experimental evidence to date for charge transfer/secondary orbital interactions in the reactions of peroxyl radicals with good H-atom donors.

  2. WAX INDUCER1 (HvWIN1) transcription factor regulates free fatty acid biosynthetic genes to reinforce cuticle to resist Fusarium head blight in barley spikelets

    PubMed Central

    Kumar, Arun; Yogendra, Kalenahalli N.; Karre, Shailesh; Kushalappa, Ajjamada C.; Dion, Yves; Choo, Thin M.

    2016-01-01

    Fusarium head blight (FHB), caused by Fusarium graminearum, is one of the most devastating diseases of wheat and barley. Resistance to FHB is highly complex and quantitative in nature, and is most often classified as resistance to spikelet infection and resistance to spread of pathogen through the rachis. In the present study, a resistant (CI9831) and a susceptible (H106-371) two-row barley genotypes, with contrasting levels of spikelet resistance to FHB, pathogen or mock-inoculated, were profiled for metabolites based on liquid chromatography and high resolution mass spectrometry. The key resistance-related (RR) metabolites belonging to fatty acids, phenylpropanoids, flavonoids and terpenoid biosynthetic pathways were identified. The free fatty acids (FFAs) linoleic and palmitic acids were among the highest fold change RR induced (RRI) metabolites. These FFAs are deposited as cutin monomers and oligomers to reinforce the cuticle, which acts as a barrier to pathogen entry. Quantitative real-time PCR studies revealed higher expressions of KAS2, CYP86A2, CYP89A2, LACS2 and WAX INDUCER1 (HvWIN1) transcription factor in the pathogen-inoculated resistant genotype than in the susceptible genotype. Knockdown of HvWIN1 by virus-induced genes silencing (VIGS) in resistant genotype upon pathogen inoculation increased the disease severity and fungal biomass, and decreased the abundance of FFAs like linoleic and palmitic acids. Notably, the expression of CYP86A2, CYP89A2 and LAC2 genes was also suppressed, proving the link of HvWIN1 in regulating these genes in cuticle biosynthesis as a defense response. PMID:27194736

  3. Specificity of recognition of mRNA 5' cap by human nuclear cap-binding complex.

    PubMed

    Worch, Remigiusz; Niedzwiecka, Anna; Stepinski, Janusz; Mazza, Catherine; Jankowska-Anyszka, Marzena; Darzynkiewicz, Edward; Cusack, Stephen; Stolarski, Ryszard

    2005-09-01

    The heterodimeric nuclear cap-binding complex (CBC) binds to the mono-methylated 5' cap of eukaryotic RNA polymerase II transcripts such as mRNA and U snRNA. The binding is important for nuclear maturation of mRNAs and possibly in the first round of translation and nonsense-mediated decay. It is also essential for nuclear export of U snRNAs in metazoans. We report characterization by fluorescence spectroscopy of the recognition of 5' capped RNA by human CBC. The association constants (K(as)) for 17 mono- and dinucleotide cap analogs as well as for the oligomer m7GpppA(m2') pU(m2')pA(m2') cover the range from 1.8 x 10(6) M(-1) to 2.3 x 10(8) M(-1). Higher affinity for CBC is observed for the dinucleotide compared with mononucleotide analogs, especially for those containing a purine nucleoside next to m7G. The mRNA tetramer associates with CBC as tightly as the dinucleotide analogs. Replacement of Tyr138 by alanine in the CBP20 subunit of CBC reduces the cap affinity except for the mononucleotide analogs, consistent with the crystallographic observation of the second base stacking on this residue. Our spectroscopic studies showed that contrary to the other known cap-binding proteins, the first two nucleotides of a capped-RNA are indispensable for its specific recognition by CBC. Differences in the cap binding of CBC compared with the eukaryotic translation initiation factor 4E (eIF4E) are analyzed and discussed regarding replacement of CBC by eIF4E.

  4. Diverse role of three tyrosines in binding of the RNA 5' cap to the human nuclear cap binding complex.

    PubMed

    Worch, Remigiusz; Jankowska-Anyszka, Marzena; Niedzwiecka, Anna; Stepinski, Janusz; Mazza, Catherine; Darzynkiewicz, Edward; Cusack, Stephen; Stolarski, Ryszard

    2009-01-16

    The heterodimeric nuclear cap-binding complex (CBC) specifically recognizes the monomethylguanosine 5' cap structure of the eukaryotic RNA polymerase II transcripts such as mRNA and U snRNA. The binding is essential for nuclear maturation of mRNA, for nuclear export of U snRNA in metazoans, and for nonsense-mediated decay of mRNA and the pioneer round of translation. We analysed the recognition of the cap by native human CBC and mutants in which each tyrosine that stacks with the 7-methylguanosine moiety was replaced by phenylalanine or alanine and both tyrosines were replaced by phenylalanines. The equilibrium association constants (K(as)) for two selected cap analogues, P(1)-7-methylguanosine-5' P(3)-guanosine-5' triphosphate and 7-methylguanosine triphosphate, were determined by two independent methods, fluorescence titration and surface plasmon resonance. We could distinguish two tyrosines, Y43 and Y20, in stabilization of the cap inside the CBC-binding pocket. In particular, lack of Y20 in CBC leads to a greater affinity of the mono- than the dinucleotide cap analogue, in contrast to the wild-type protein. A crucial role of cation-pi stacking in the mechanism of the specific cap recognition by CBC was postulated from the comparison of the experimentally derived Gibbs free binding energy (DeltaG degrees) with the stacking energy (DeltaE) of the 7-methylguanosine/Y binary and ternary complexes calculated by the Møller-Plesset second-order perturbation method. The resulting kinetic model of the association between the capped RNA and CBC, based on the experimental data and quantum calculations, is discussed with respect to the "CBC-to-eukaryotic initiation factor 4E handoff" of mRNA.

  5. Analytical Treatment of Forecasts of Electric Energy Consumption in Latvia

    NASA Astrophysics Data System (ADS)

    Balodis, M.; Gavars, V.; Andersons, J.

    2014-06-01

    In the paper, the changes in electric energy consumption are analyzed as associated with structural changes in the Latvian economy of postsocialistic period. To the analysis, a particular approach is applied, which consists in comparison of the basic and specific electricity consumption indices in West-, Central-, and East-European states for the time span of 1990-2010, with differences and tendencies of changes revealed. Tendencies of the type are determined for the electric energy consumption in Latvia, and recommendations are given for the use of such indices in the relevant forecasts. Rakstā apskatītas elektroenerģijas patēriņa izmaiņas, kas saistītas ar Latvijas postsociālisma perioda ekonomikas strukturālām izmaiņām. Rakstā dota Latvijas galveno elektroenerģijas patēriņa indikatoru analīze, lietojot īpašu pieeju - Rietumeiropas, Centrāleiropas un Austrumeiropas valstu indikatoru salīdzinājumu. Analizēts periods no 1990. gada līdz 2010. gadam. Salīdzināti Eiropas valstu grupu īpatnējie elektroenerģijas patēriņa indikatori un noskaidrotas to atšķirības un izmaiņu tendences. Noteiktas elektroenerģijas patēriņa izmaiņu tendences Latvijā. Dotas rekomendācijas par šo indikatoru izmantošanu elektroenerģijas patēriņa prognozēšanā. 07.05.2014.

  6. Electric Machines with Non-Radially Mounted Rectangular Permanent Magnets / Elektriskās Mašīnas Ar Prizmatiskiem Neradiāli Novietotiem Pastāvīgajiem Magnētiem

    NASA Astrophysics Data System (ADS)

    Levin, N.; Pugachev, V.; Dirba, J.; Lavrinovicha, L.

    2013-04-01

    The authors analyze the advantages and disadvantages of brushless synchronous electric machines with radially and non-radially mounted rectangular permanent magnets. The results show that the proposed nonradial mounting of permanent magnets considered in the paper, in several cases (e.g. multi-pole brushless generators with tooth windings of the armature) allows achievement of the following advantages: better technology of manufacturing the electric machine owing to simple packing of the stator winding in the stator open slots, which also increases the copper slot fillfactor; reduction in the mass-and-size of permanent magnets at least twice; significantly lower cost of the electric machine; and, finally, its greater specific power. Darbā tiek analizētas priekšrocības un trūkumi sinhronām bezkontaktu mašīnām ar radiāli un neradiāli novietotiem prizmatiskiem pastāvīgajiem magnētiem. Parādīts, ka vairākos gadījumos, piemēram, daudzpolu bezkontaktu sinhronajos ģeneratoros ar zobu tinumiem, neradiāls pastāvīgo magnētu izvietojums nodrošina vairākas priekšrocības: uzlabojas mašīnas izgatavošanas tehnoloģija, jo statora atvērtajās rievās vieglāk novietot tinumus un iespējams sasniegt augstāku rievas aizpildījuma koeficientu; samazinās pastāvīgo magnētu masa un izmaksas; palielinās mašīnas īpatnēja jauda.

  7. Characterization and Thermal Dehydration Kinetics of Highly Crystalline Mcallisterite, Synthesized at Low Temperatures

    PubMed Central

    Senberber, Fatma Tugce

    2014-01-01

    The hydrothermal synthesis of a mcallisterite (Mg2(B6O7(OH)6)2·9(H2O)) mineral at low temperatures was characterized. For this purpose, several reaction temperatures (0–70°C) and reaction times (30–240 min) were studied. Synthesized minerals were subjected to X-ray diffraction (XRD), fourier transform infrared (FT-IR), and Raman spectroscopies and scanning electron microscopy (SEM). Additionally, experimental analyses of boron trioxide (B2O3) content and reaction yields were performed. Furthermore, thermal gravimetry and differential thermal analysis (TG/DTA) were used for the determination of thermal dehydration kinetics. According to the XRD results, mcallisterite, which has a powder diffraction file (pdf) number of “01-070-1902,” was formed under certain reaction parameters. Pure crystalline mcallisterite had diagnostic FT-IR and Raman vibration peaks and according to the SEM analysis, for the minerals which were synthesized at 60°C and 30 min of reaction time, particle size was between 398.30 and 700.06 nm. Its B2O3 content and reaction yield were 50.80 ± 1.12% and 85.80 ± 0.61%, respectively. Finally, average activation energies (conversion values (α) that were selected between 0.1 and 0.6) were calculated as 100.40 kJ/mol and 98.31 kJ/mol according to Ozawa and Kissinger-Akahira-Sunose (KAS) methods, respectively. PMID:24719585

  8. Loss of compatibility might explain resistance of the Arabidopsis thaliana accession Te-0 to Golovinomyces cichoracearum

    PubMed Central

    2012-01-01

    Background The establishment of compatibility between plants and pathogens requires compliance with various conditions, such as recognition of the right host, suppression of defence mechanisms, and maintenance of an environment allowing pathogen reproduction. To date, most of the plant factors required to sustain compatibility remain unknown, with the few best characterized being those interfering with defence responses. A suitable system to study host compatibility factors is the interaction between Arabidopsis thaliana and the powdery mildew (PM) Golovinomyces cichoracearum. As an obligate biotrophic pathogen, this fungus must establish compatibility in order to perpetuate. In turn, A. thaliana displays natural variation for susceptibility to this invader, with some accessions showing full susceptibility (Col-0), and others monogenic dominant resistance (Kas-1). Interestingly, Te-0, among other accessions, displays recessive partial resistance to this PM. Results In this study, we characterized the interaction of G. cichoracearum with Te-0 plants to investigate the basis of this plant resistance. We found that Te-0´s incompatibility was not associated with hyper-activation of host inducible defences. Te-0 plants allowed germination of conidia and development of functional haustoria, but could not support the formation of mature conidiophores. Using a suppressive subtractive hybridization technique, we identified plant genes showing differential expression between resistant Te-0 and susceptible Col-0 plants at the fungal pre-conidiation stage. Conclusions Te-0 resistance is likely caused by loss of host compatibility and not by stimulation of inducible defences. Conidiophores formation is the main constraint for completion of fungal life cycle in Te-0 plants. The system here described allowed the identification of genes proposed as markers for susceptibility to this PM. PMID:22883024

  9. Cine-servo lens technology for 4K broadcast and cinematography

    NASA Astrophysics Data System (ADS)

    Nurishi, Ryuji; Wakazono, Tsuyoshi; Usui, Fumiaki

    2015-09-01

    Central to the rapid evolution of 4K image capture technology in the past few years, deployment of large-format cameras with Super35mm Single Sensors is increasing in TV production for diverse shows such as dramas, documentaries, wildlife, and sports. While large format image capture has been the standard in the cinema world for quite some time, the recent experiences within the broadcast industry have revealed a variety of requirement differences for large format lenses compared to those of the cinema industry. A typical requirement for a broadcast lens is a considerably higher zoom ratio in order to avoid changing lenses in the middle of a live event, which is mostly not the case for traditional cinema productions. Another example is the need for compact size, light weight, and servo operability for a single camera operator shooting in a shoulder-mount ENG style. On the other hand, there are new requirements that are common to both worlds, such as smooth and seamless change in angle of view throughout the long zoom range, which potentially offers new image expression that never existed in the past. This paper will discuss the requirements from the two industries of cinema and broadcast, while at the same time introducing the new technologies and new optical design concepts applied to our latest "CINE-SERVO" lens series which presently consists of two models, CN7x17KAS-S and CN20x50IAS-H. It will further explain how Canon has realized 4K optical performance and fast servo control while simultaneously achieving compact size, light weight and high zoom ratio, by referring to patent-pending technologies such as the optical power layout, lens construction, and glass material combinations.

  10. Thermal degradation of paper industry wastes from a recovered paper mill using TGA. Characterization and gasification test.

    PubMed

    Arenales Rivera, Jorge; Pérez López, Virginia; Ramos Casado, Raquel; Sánchez Hervás, José-María

    2016-01-01

    In this survey, a refuse derived fuel (RDF) was produced from paper industry wastes through a mechanical treatment (MT). The two main wastes generated from a recovered paper mill were rejects and de-inking sludge, which were produced principally in the pulping and de-inking processes, respectively. This work presents raw wastes characterization, fuel preparation and gasification tests performed in a circulating fluidized bed (CFB) gasifier pilot plant. The characterization was carried out by proximate and ultimate analysis. Several blends of pre-conditioned rejects and de-inking sludge were densified by means of pelletizing, studying the energy consumption and its quality properties. Besides, thermal degradation of blends was studied under thermogravimetric analysis (TGA). The experimental runs were made from 30 to 900°C in nitrogen atmosphere at three heating ranges, β=5, 10 and 20°C/min. Two thermal stages were identified during the thermal degradation, which are linked to cellulose and plastic degradation. In addition, kinetics parameters were estimated by the application of non-isothermal methods: Kissinger-Akahira-Sunose (KAS), Flynn-Ozawa-Wall (FOW) and Coats and Redfern. The activation energy values were about 140-160 kJ/mol and 60-80 kJ/mol for plastic and cellulosic materials, respectively. Regarding waste valorisation, a blend composed of 95% of rejects and 5% of de-inking sludge was selected for gasification tests. The energy consumption during the preparation was recorded and a gasification tests were done to prove the usability of these pellets in a CFB gasifier. The main results were a net calorific value (NCV) of 5 MJ/Nm(3) and a total tar content of 11.44 g/Nm(3) at an equivalence ratio (ER) of 0.3. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Multiconformation Continuum Electrostatics Analysis of the Effects of a Buried Asp Introduced Near Heme a in Rb. sphaeroides Cytochrome c Oxidase

    PubMed Central

    Zhang, Jun; Gunner, M.R.

    2013-01-01

    Cytochrome c oxidase (CcO) reduces O2 to water via a series of proton coupled electron transfers generating a transmembrane electrochemical gradient. Coupling electron and proton transfer requires changing buried residues pKas at each stage in the reaction cycle. Heme a is a key cofactor in the CcO electron transfer chain. Mutation of Ser44 to Asp has been reported (Mills et al Biochemistry (2008) 47, 11499-11509), changing the hydrogen bond acceptor from His102, the Heme a axial ligand in Rhodobactor sphaeroides CcO. This adds an acidic residue to the CcO interior. The electrochemical behavior of Heme a in wild type and S44D CcO is compared using the continuum electrostatics program MCCE. The introduced, deeply buried Asp remains ionized at physiological pH only when the nearby heme is oxidized. Heme a reduction is now calculated to be strongly coupled to Asp proton binding, while with Ser44 it is weakly coupled to small protonation shifts at multiple sites, increasing the pH dependence in the mutant. At pH 7, the partially ionized Asp44 is calculated to lower the Heme redox potential by 50 mV as expected given the thermodynamics of coupled electron and proton transfers. This highlights an inconsistency in the experimental results where a low Asp pKa is found together with a stabilized reduced Heme. The stabilization of a model complex heme oxidation by a hydrogen bond to the axial His ligand calculated with Continuum Electrostatics and with Density Functional Theory was in good agreement. PMID:20701325

  12. [Pharmacological effects of N-acetyl-L-cysteine on the respiratory tract. (I). Quantitative and qualitative changes in respiratory tract fluid and sputum (author's transl)].

    PubMed

    Kogi, K; Saito, T; Kasé, Y; Hitoshi, T

    1981-06-01

    The following three experiments were performed to determine the effects of N-acetyl-L-cysteine (NAC) on the quantity and quality of respiratory tract fluid (RTF) and sputum. All drugs used were administered into the stomach through a gastric tube. 1) Indirect measurement of bronchial secretion in rats, which was expressed by the amounts of dye excreted into the respiratory tract, was carried out according the the Sakuno's method, with some modification. Some expectorants of the secretomotor type, such as bromhexine and pilocarpine, significantly increased the secretion, even at low doses. On the other hand, mucolytic agents such as NAC augmented the secretion only in doses of 500 to 1500 mg/kg. 2)As a direct method of measurements, Kasé's modification of Perry and Boyd's method was used to collect RTF, quantitatively, from rabbits. The RTF of healthy rabbits was colorless and watery. The administration of NAC in doses of 500 to 1500 mg/kg augmented the output volume and RTF became slightly turbid, probably due to an increase in the viscous mucus. 3) Rabbits with subacute bronchitis were prepared by long-term exposure to air contaminated with SO2 gas and sputa were collected before and after administration of NAC, respectively, according to the Kase's method. The sputa were opalescent and viscous gel included nodular masses. The administration of NAC, 1000 and 1500 mg/kg resulted in a dose dependent decrease in the relative viscosity. The percent-decreased in viscosity with NAC was statistically correlated with that in amounts of dry matter, those in protein and polysaccharide in the sputa. From the results described above, it was concluded that NAC given into the stomach can liquefy sputum by splitting mucoprotein disulphide linkages, that is, altering the rheological characteristics of sputum to facilitate expectoration.

  13. Interleukin 6 supports the maintenance of p53 tumor suppressor gene promoter methylation.

    PubMed

    Hodge, David R; Peng, Benjamin; Cherry, James C; Hurt, Elaine M; Fox, Stephen D; Kelley, James A; Munroe, David J; Farrar, William L

    2005-06-01

    A strong association exists between states of chronic inflammation and cancer, and it is believed that mediators of inflammation may be responsible for this phenomenon. Interleukin 6 (IL-6) is an inflammatory cytokine known to play a role in the growth and survival of many types of tumors, yet the mechanisms employed by this pleomorphic cytokine to accomplish this feat are still poorly understood. Another important factor in tumor development seems to be the hypermethylation of CpG islands located within the promoter regions of tumor suppressor genes. This common epigenetic alteration enables tumor cells to reduce or inactivate the expression of important tumor suppressor and cell cycle regulatory genes. Here we show that in the IL-6-responsive human multiple myeloma cell line KAS 6/1, the promoter region of p53 is epigenetically modified by methyltransferases, resulting in decreased levels of expression. Furthermore, cells treated with IL-6 exhibit an increase in the expression of the DNA maintenance methylation enzyme, DNMT-1. The DNA methyltransferase inhibitor zebularine reverses the methylation of the p53 promoter, allowing the resumption of its expression. However, when zebularine is withdrawn from the cells, the reestablishment of the original CpG island methylation within the p53 promoter does not occur in the absence of IL-6, and cells which do not receive IL-6 eventually die, as p53 expression continues unchecked by remethylation. Interestingly, this loss of viability seems to involve not the withdrawal of cytokine, but the inability of the cell to resilence the promoter. Consistent with this model, when cells that express IL-6 in an autocrine fashion are subjected to identical treatment, p53 expression is reduced shortly after withdrawal of zebularine. Therefore, it seems IL-6 is capable of maintaining promoter methylation thus representing one of the possible mechanisms used by inflammatory mediators in the growth and survival of tumors.

  14. Role of embB Codon 306 Mutations in Mycobacterium tuberculosis Revisited: a Novel Association with Broad Drug Resistance and IS6110 Clustering Rather than Ethambutol Resistance

    PubMed Central

    Hazbón, Manzour Hernando; Bobadilla del Valle, Miriam; Guerrero, Marta Inírida; Varma-Basil, Mandira; Filliol, Ingrid; Cavatore, Magali; Colangeli, Roberto; Safi, Hassan; Billman-Jacobe, Helen; Lavender, Caroline; Fyfe, Janet; García-García, Lourdes; Davidow, Amy; Brimacombe, Michael; León, Clara Inés; Porras, Tania; Bose, Mridula; Chaves, Fernando; Eisenach, Kathleen D.; Sifuentes-Osornio, José; Ponce de León, Alfredo; Cave, M. Donald; Alland, David

    2005-01-01

    Mutations at position 306 of embB (embB306) have been proposed as a marker for ethambutol resistance in Mycobacterium tuberculosis; however, recent reports of embB306 mutations in ethambutol-susceptible isolates caused us to question the biological role of this mutation. We tested 1,020 clinical M. tuberculosis isolates with different drug susceptibility patterns and of different geographical origins for associations between embB306 mutations, drug resistance patterns, and major genetic group. One hundred isolates (10%) contained a mutation in embB306; however, only 55 of these mutants were ethambutol resistant. Mutations in embB306 could not be uniquely associated with any particular type of drug resistance and were found in all three major genetic groups. A striking association was observed between these mutations and resistance to any drug (P < 0.001), and the association between embB306 mutations and resistance to increasing numbers of drugs was highly significant (P < 0.001 for trend). We examined the association between embB306 mutations and IS6110 clustering (as a proxy for transmission) among all drug-resistant isolates. Mutations in embB306 were significantly associated with clustering by univariate analysis (odds ratio, 2.44; P = 0.004). In a multivariate model that also included mutations in katG315, katG463, gyrA95, and kasA269, only mutations in embB306 (odds ratio, 2.14; P = 0.008) and katG315 (odds ratio, 1.99; P = 0.015) were found to be independently associated with clustering. In conclusion, embB306 mutations do not cause classical ethambutol resistance but may predispose M. tuberculosis isolates to the development of resistance to increasing numbers of antibiotics and may increase the ability of drug-resistant isolates to be transmitted between subjects. PMID:16127055

  15. Can Citizen Science Survey Non-indigenous Fish Species in the Eastern Mediterranean Sea?

    NASA Astrophysics Data System (ADS)

    Bodilis, P.; Louisy, P.; Draman, M.; Arceo, H. O.; Francour, P.

    2014-01-01

    Engaging non-scientists to survey ecosystems, a process known as citizen science has been adopted worldwide. For the first time, this was applied to monitor fish assemblages in the Kas Peninsula, Turkey, an area known for its important Lessepsian fish populations. For 3 years (2004, 2007 and 2010), fish assemblages were surveyed using underwater visual census by transect method. A total of 29 species was observed, seven of which were Lessepsian species. Results show a significant increase in the Lessepsian species over the study period. In 2004, they represented 34 % of the total abundance, increasing to >61 % in 2010. Differences were observed in the progression of populations between two invasive herbivores, Siganus rivulatus and Siganus luridus (Siganidae), and two native herbivores, Sparisoma cretense (Scaridae) and Sarpa salpa (Sparidae). The siganids were recorded each year in all sites, whereas S. cretense was regularly observed in fewer numbers, while S. salpa was rarely censused. Abundance of Siganus spp. increased threefold in 6 years while abundances of S. cretense and S. salpa remained stable. S. rivulatus was the most abundant among the four species. Its competitive superiority may be due to its greater adaptability to fluctuating environmental conditions and biological traits, e.g. rapid growth, earlier sexual maturity, high fecundity. Because siganids are herbivorous, their presence can strongly impact algal ecosystems. It is then important to follow their spreading at a large scale, but this can be challenging due to the limited number of scientists. Adopting citizen science can thus be a useful strategy to monitor the spread of invasive species in the Mediterranean.

  16. Thermal analysis during partial carbonizing process of rhubarb, moutan and burnet

    PubMed Central

    Ma, Junnan; Meng, Xianglong; Guo, Xiaohui; Lan, Yaru; Zhang, Shuosheng

    2017-01-01

    Control of temperature and duration of partial carbonization for Chinese medicines have been mainly based on experience of the processors. No quantitative methods and parameters are available that can be used to precisely control the temperature and determine the energy changes during the process. In our research, with a simulated atmosphere air condition, the partial carbonization processes of three Chinese herb medicines rhubarb, moutan and burnet were simulated at different heating rates (5, 10 and 20°C • min-1) and analyzed by thermal gravimetric analysis (TGA) to quantify the upper limits of the temperature. The activation energy was calculated with Friedman, Kissinger-Akahira-Sunose (KAS) method and Ozawa-Flynn-Wall (OFW) methods in iso-conversional models and independent parallel reaction model (IPR). The upper temperatures were calculated to be 280, 184 and 246°C for rhubarb, moutan and burnet, respectively, at corresponding conversion rates of 0.4, 0.2 and 0.1. Calculation of the activation energy has been found impossible with the IPR model. Results obtained from the three iso-conversional methods were different. For rhubarb and burnet, the conversion rates at the upper temperature limits were at the highest or second highest activation energy, while for moutan, it was at the lowest value of activation energy. These results confirmed scientific rationales of traditional Chinese medicine theory that rhubarb and burnet be prepared at high temperature and moutan be prepared at medium temperature. Application of thermal analysis techniques would broaden and deepen traditional Chinese medicine research, and are applicable to the processing of medicinal materials including traditional Chinese medicines. Results obtained from the study could provide new ideas and methods for research to modernize the preparation of traditional Chinese medicines. PMID:28323877

  17. Natural Variation of Cold Deacclimation Correlates with Variation of Cold-Acclimation of the Plastid Antioxidant System in Arabidopsis thaliana Accessions.

    PubMed

    Juszczak, Ilona; Cvetkovic, Jelena; Zuther, Ellen; Hincha, Dirk K; Baier, Margarete

    2016-01-01

    Temperature variations impact on the balance between photosynthetic electron transport and electron-consuming assimilation reactions and transiently increase generation of reactive oxygen species (ROS). Previous studies demonstrated that the expression of C-repeat binding factors (CBFs), which activate cold acclimation reactions, respond to chloroplast ROS signals and that cold deacclimation is partly halted for days after the transfer of acclimated plants to optimal growth conditions in four Arabidopsis accessions from cold-continental habitats. We hypothesized that these accessions differ from others in the regulation of the plastid antioxidant system (PAS). In the present study, we compared the expression intensity of the 12 most prominent PAS genes for peroxidases, superoxide dismutase and low molecular weight antioxidant regenerating enzymes in 10 Arabidopsis accessions with regulation of CBF and COR (cold regulated genes) transcript levels and cold-regulated metabolite levels prior to cold, after 2 week long cold acclimation and during the first 3 days of deacclimation. In the accessions with prolonged activation of cold responses, by trend, weaker induction of various cold-inducible PAS genes and stronger decreases in the expression of negatively cold-regulated PAS genes were observed. Low PAS gene expression delayed the post-cold decrease in H2O2 levels after transfer of the plants from cold to optimal growth conditions. We conclude that weaker expression of various PAS genes in the cold is an adapted strategy of the Arabidopsis accessions N14, N13, Ms-0, and Kas-1 to avoid full inactivation of cold-responses in the first days after the end of the cold period.

  18. An R2R3-MYB Transcription Factor Regulates Capsaicinoid Biosynthesis1[OPEN

    PubMed Central

    Arce-Rodríguez, Magda L.

    2017-01-01

    Capsaicinoids are responsible for the hot taste of chili peppers. They are restricted to the genus Capsicum and are synthesized by the acylation of the aromatic compound vanillylamine (derived from the phenylpropanoid pathway) with a branched-chain fatty acid by the catalysis of the putative enzyme capsaicinoid synthase. R2R3-MYB transcription factors have been reported in different species of plants as regulators of structural genes of the phenylpropanoid pathway; therefore, we hypothesized that MYB genes might be involved in the regulation of the biosynthesis of pungent compounds. In this study, an R2R3-MYB transcription factor gene, designated CaMYB31, was isolated and characterized in Capsicum annuum ‘Tampiqueño 74’. Bioinformatic analysis suggested that CaMYB31 could be involved in secondary metabolism, stress and plant hormone responses, and development. CaMYB31 expression analysis from placental tissue of pungent and nonpungent chili pepper fruits showed a positive correlation with the structural genes Ca4H, Comt, Kas, pAmt, and AT3 expression and also with the content of capsaicin and dihydrocapsacin during fruit development. However, CaMYB31 also was expressed in vegetative tissues (leaves, roots, and stems). Moreover, CaMYB31 silencing significantly reduced the expression of capsaicinoid biosynthetic genes and the capsaicinoid content. Additionally, CaMYB31 expression was affected by the plant hormones indoleacetic acid, jasmonic acid, salicylic acid, and gibberellic acid or by wounding, temperature, and light, factors known to affect the production of capsaicinoids. These findings indicate that CaMYB31 is indeed involved in the regulation of structural genes of the capsaicinoid biosynthetic pathway. PMID:28483879

  19. An R2R3-MYB Transcription Factor Regulates Capsaicinoid Biosynthesis.

    PubMed

    Arce-Rodríguez, Magda L; Ochoa-Alejo, Neftalí

    2017-07-01

    Capsaicinoids are responsible for the hot taste of chili peppers. They are restricted to the genus Capsicum and are synthesized by the acylation of the aromatic compound vanillylamine (derived from the phenylpropanoid pathway) with a branched-chain fatty acid by the catalysis of the putative enzyme capsaicinoid synthase. R2R3-MYB transcription factors have been reported in different species of plants as regulators of structural genes of the phenylpropanoid pathway; therefore, we hypothesized that MYB genes might be involved in the regulation of the biosynthesis of pungent compounds. In this study, an R2R3-MYB transcription factor gene, designated CaMYB31, was isolated and characterized in Capsicum annuum 'Tampiqueño 74'. Bioinformatic analysis suggested that CaMYB31 could be involved in secondary metabolism, stress and plant hormone responses, and development. CaMYB31 expression analysis from placental tissue of pungent and nonpungent chili pepper fruits showed a positive correlation with the structural genes Ca4H, Comt, Kas, pAmt, and AT3 expression and also with the content of capsaicin and dihydrocapsacin during fruit development. However, CaMYB31 also was expressed in vegetative tissues (leaves, roots, and stems). Moreover, CaMYB31 silencing significantly reduced the expression of capsaicinoid biosynthetic genes and the capsaicinoid content. Additionally, CaMYB31 expression was affected by the plant hormones indoleacetic acid, jasmonic acid, salicylic acid, and gibberellic acid or by wounding, temperature, and light, factors known to affect the production of capsaicinoids. These findings indicate that CaMYB31 is indeed involved in the regulation of structural genes of the capsaicinoid biosynthetic pathway. © 2017 American Society of Plant Biologists. All Rights Reserved.

  20. Difference in capsaicinoid biosynthesis gene expression in the pericarp reveals elevation of capsaicinoid contents in chili peppers (Capsicum chinense).

    PubMed

    Tanaka, Yoshiyuki; Nakashima, Fumihiro; Kirii, Erasmus; Goto, Tanjuro; Yoshida, Yuichi; Yasuba, Ken-Ichiro

    2017-02-01

    This research reveals that the up-regulated expression of multiple capsaicinoid biosynthetic genes in pericarp tissue leads to the elevation of total capsaicinoid content in chili pepper fruit. Capsaicinoids are health-functional compounds that are produced uniquely in chili pepper fruits. A high capsaicinoid level is one of the major parameters determining the commercial quality and health-promoting properties of chili peppers. To investigate the mechanisms responsible for its high contents, we compared an extremely pungent cultivar 'Trinidad Moruga Scorpion Yellow' (MY) with other cultivars of different pungency levels (Fushimi-amanaga, Takanotsume, Red Habanero). Capsaicinoid concentrations were markedly higher in MY fruit (23.9 mg/g DW) than in other pungent cultivars including 'Red Habanero' (HB) fruit (14.3 mg/g DW). Comparative analysis of MY and HB reveals that both cultivars accumulated similar capsaicinoid concentrations in the placental septum, with that in the HB pericarp (1.8 mg/g DW) being markedly lower than that in the placental septum (69.1 mg/g DW). The capsaicinoid concentration in HB fruit is dependent on the placental septum, as reported in other accessions. Therefore, even though placental septum tissue contains high capsaicinoid concentrations, those in the pericarp and seeds attenuated its total content. In contrast, the MY pericarp exhibited a markedly higher concentration (23.2 mg/g DW). A qRT-PCR analysis revealed that multiple capsaicinoid biosynthetic pathway genes (Pun1, pAMT, KAS, and BCAT) were strongly up-regulated in placental septum of pungent cultivars. The genes were expressed exclusively in the MY pericarp, but were barely detected in the pericarps of other pungent cultivars. Collectively, the present study indicates that the up-regulated expression of these genes not only in placental septum but also in pericarp plays an important role in driving capsaicinoid accumulation in the whole fruit.

  1. Electrostatic dominoes: long distance propagation of mutational effects in photosynthetic reaction centers of Rhodobacter capsulatus.

    PubMed

    Sebban, P; Maróti, P; Schiffer, M; Hanson, D K

    1995-07-04

    Two point mutants from the purple bacterium Rhodobacter capsulatus, both modified in the M protein of the photosynthetic reaction center, have been studied by flash-induced absorbance spectroscopy. These strains carry either the M231Arg --> Leu or M43ASN --> Asp mutations, which are located 9 and 15 A, respectively, from the terminal electron acceptor QB. In the wild-type Rb. sphaeroides structure, M231Arg is involved in a conserved salt bridge with H125Glu and H232Glu and M43Asn is located among several polar residues that form or surround the QB binding site. These substitutions were originally uncovered in phenotypic revertants isolated from the photosynthetically incompetent L212Glu-L213Asp --> Ala-Ala site-specific double mutant. As second-site suppressor mutations, they have been shown to restore the proton transfer function that is interrupted in the L212Ala-L213Ala double mutant. The electrostatic effects that are induced in reaction centers by the M231Arg --> Leu and M43Asn --> Asp substitutions are roughly the same in either the double-mutant or wild-type backgrounds. In a reaction center that is otherwise wild type in sequence, they decrease the free energy gap between the QA- and QB- states by 24 +/- 5 and 45 +/- 5 meV, respectively. The pH dependences of K2, the QA-QB <--> QAQB- equilibrium constant, are altered in reaction centers that carry either of these substitutions, revealing differences in the pKas of titratable groups compared to the wild type.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. The titrations of Asp-85 and of the cation binding residues in bacteriorhodopsin are not coupled.

    PubMed

    Eliash, T; Ottolenghi, M; Sheves, M

    1999-03-26

    An outstanding problem relating to the structure and function of bacteriorhodopsin (bR), which is the only protein in the purple membrane of the photosynthetic microorganism Halobacterium salinarium, is the relation between the titration of Asp-85 and the binding/unbinding of metal cations. An extensively accepted working hypothesis has been that the two titrations are coupled, namely, protonation of Asp-85 (located in the vicinity of the retinal chromophore) and cation unbinding occur concurrently. We have carried out a series of experiments in which the purple blue equilibrium and the binding of Mn2+ ions (monitored by electron spin resonance) were followed as a function of pH for several (1-4) R = [Mn2+]/[bR] molar ratios. Data were obtained for native bR, bR mutants, artificial bR and chemically modified bR. We find that in the native pigment the two titrations are separated by more than a pKa unit [delta pKa = pKa(P/B)-pKa(Mn2+) = (4.2-2.8) = 1.4]. In the non-native systems, delta pKa values as high as 5 units, as well as negative delta pKas, are observed. We conclude that the pH titration of cation binding residues in bR is not directly related to the titration of Asp-85. This conclusion is relevant to the nature of the high affinity cation sites in bR and to their role in the photosynthetic function of the pigment.

  3. Indole-3-acetic acid (IAA) induced changes in oil content, fatty acid profiles and expression of four fatty acid biosynthetic genes in Chlorella vulgaris at early stationary growth phase.

    PubMed

    Jusoh, Malinna; Loh, Saw Hong; Chuah, Tse Seng; Aziz, Ahmad; Cha, Thye San

    2015-03-01

    Microalgae lipids and oils are potential candidates for renewable biodiesel. Many microalgae species accumulate a substantial amount of lipids and oils under environmental stresses. However, low growth rate under these adverse conditions account for the decrease in overall biomass productivity which directly influence the oil yield. This study was undertaken to investigate the effect of exogenously added auxin (indole-3-acetic acid; IAA) on the oil content, fatty acid compositions, and the expression of fatty acid biosynthetic genes in Chlorella vulgaris (UMT-M1). Auxin has been shown to regulate growth and metabolite production of several microalgae. Results showed that oil accumulation was highest on days after treatment (DAT)-2 with enriched levels of palmitic (C16:0) and stearic (C18:0) acids, while the linoleic (C18:2) and α-linolenic (C18:3n3) acids levels were markedly reduced by IAA. The elevated levels of saturated fatty acids (C16:0 and C18:0) were consistent with high expression of the β-ketoacyl ACP synthase I (KAS I) gene, while low expression of omega-6 fatty acid desaturase (ω-6 FAD) gene was consistent with low production of C18:2. However, the increment of stearoyl-ACP desaturase (SAD) gene expression upon IAA induction did not coincide with oleic acid (C18:1) production. The expression of omega-3 fatty acid desaturase (ω-3 FAD) gene showed a positive correlation with the synthesis of PUFA and C18:3n3.

  4. Interaction of Xanthomonas campestris with Arabidopsis thaliana: characterization of a gene from X. c. pv. raphani that confers avirulence to most A. thaliana accessions.

    PubMed

    Parker, J E; Barber, C E; Fan, M J; Daniels, M J

    1993-01-01

    Infiltration of leaves of Arabidopsis thaliana accession Columbia with Xanthomonas campestris pathovar campestris leads to bacterial growth and disease symptoms reminiscent of those incited in Brassica plants inoculated under the same conditions. A search among A. thaliana accessions for variation in the reaction phenotype to strains of X. campestris pathovars campestris, aberrans, and raphani showed that there were no clear differential responses between plant accessions to the individual bacterial strains tested. X. c. pv. raphani strain 1067 was avirulent to all A. thaliana accessions tested. A gene was cloned from X. c. pv. raphani 1067 which, when transferred into the virulent X. c. pv. campestris strain 8004, strongly reduced symptom development and bacterial growth in A. thaliana Columbia plants but did not affect virulence to Brassica plants. The gene (denoted avrXca) interacted with all A. thaliana accessions tested except one, Kas-1, which developed disease symptoms and supported growth of the transconjugant to levels similar to those with X. c. pv. campestris 8004 alone. Sequence analysis of avrXca revealed a probable open reading frame encoding a protein of 66,566 Da that has no homology with other known sequences. A sequence motif conserved among hrp genes was identified in the 5' noncoding region of avrXca, and features characteristic of a signal peptide were found in the N-terminal portion of the presumed AvrXca protein. DNA from different phytopathogenic bacteria contained sequences hybridizing with avrXca in related X. campestris pathovars but not in Erwinia or Pseudomonas strains.

  5. Differences in Organizational Structure of Insulin Receptor on Rat Adipocyte and Liver Plasma Membranes: Role of Disulfide Bonds

    NASA Astrophysics Data System (ADS)

    Schweitzer, John B.; Smith, Robert M.; Jarett, Leonard

    1980-08-01

    Binding of 125I-labeled insulin to rat liver and adipocyte plasma membranes has been investigated after treatment of the membranes with agents that modify disulfide bonds or sulfhydryl groups. Dithiothreitol, a disulfide-reducing agent, produced a bimodal response in adipocyte plasma membranes with dose-dependent increases in binding occurring over the range of 0-1 mM dithiothreitol; 5 mM dithiothreitol produced decreased binding. Insulin binding reached its maximal increase at 1 mM and was 3 times control values. Scatchard analysis of the 1 mM dithiothreitol effect revealed a straight line plot indicative of one class of sites with a Ka of 1.0× 108 M-1 which is intermediate between the two Kas obtained from the curvilinear Scatchard plot of control membranes. There was a 20-fold increase in the number of intermediate-affinity receptors compared to high-affinity receptors. The increased 125I-labeled insulin binding after dithiothreitol treatment was reversed by oxidized glutathione in a dose-dependent manner. Interposition of treatment with N-ethylmaleimide, an alkylating agent, prevented oxidized glutathione from reversing the dithiothreitol effect. Reduced glutathione produced the same effect as dithiothreitol. Liver plasma membranes treated with up to 1 mM dithiothreitol exhibited a maximum increase in insulin binding of 20% compared to control. Dithiothreitol at 5 mM decreased insulin binding below that of control membranes. The results indicate that the dithiothreitol effect on insulin binding to adipocyte plasma membranes is due to disruption of disulfide bonds, and that the structural organization of the insulin receptor on the plasma membranes is different for liver and for adipose tissue. The data imply that the insulin receptors on the plasma membrane of adipocytes possess at least two functionally distinct subclasses of disulfide bond but liver insulin receptors do not.

  6. Critical Design Features of Phenyl Carboxylate-Containing Polymer Microbicides

    PubMed Central

    Rando, Robert F.; Obara, Sakae; Osterling, Mark C.; Mankowski, Marie; Miller, Shendra R.; Ferguson, Mary L.; Krebs, Fred C.; Wigdahl, Brian; Labib, Mohamed; Kokubo, Hiroyasu

    2006-01-01

    Recent studies of cellulose-based polymers substituted with carboxylic acids like cellulose acetate phthalate (CAP) have demonstrated the utility of using carboxylic acid groups instead of the more common sulfate or sulfonate moieties. However, the pKa of the free carboxylic acid group is very important and needs careful selection. In a polymer like CAP the pKa is approximately 5.28. This means that under the low pH conditions found in the vaginal lumen, CAP would be only minimally soluble and the carboxylic acid would not be fully dissociated. These issues can be overcome by substitution of the cellulose backbone with a moiety whose free carboxylic acid group(s) has a lower pKa. Hydroxypropyl methylcellulose trimellitate (HPMCT) is structurally similar to CAP; however, its free carboxylic acids have pKas of 3.84 and 5.2. HPMCT, therefore, remains soluble and molecularly dispersed at a much lower pH than CAP. In this study, we measured the difference in solubility and dissociation between CAP and HPMCT and the effect these parameters might have on antiviral efficacy. Further experiments revealed that the degree of acid substitution of the cellulose backbone can significantly impact the overall efficacy of the polymer, thereby demonstrating the need to optimize any prospective polymer microbicide with respect to pH considerations and the degree of acid substitution. In addition, we have found HPMCT to be a potent inhibitor of CXCR4, CCR5, and dual tropic strains of human immunodeficiency virus in peripheral blood mononuclear cells. Therefore, the data presented herein strongly support further evaluation of an optimized HPMCT variant as a candidate microbicide. PMID:16940105

  7. Solid State Physics. Nitrogen Adsorption by Thermoexfoliated Graphite / Slāpekļa Adsorbcija Uz Termoeksfoliētā Grafīta

    NASA Astrophysics Data System (ADS)

    Grehov, V.; Kalnacs, J.; Matzui, L.; Knite, M.; Murashov, A.; Vilken, A.

    2013-02-01

    Adsorption by thermochemically exfoliated graphite (TEG) is studied and compared with that by other carbon structures under the same conditions. In BET determination of the specific surface area (SBET) for the TEG samples it was found that good approximation could be observed in two different pressure ranges. Such ranges of BET approximation are also visible in the isotherms of aquadag and milled graphite. The experimental results are discussed and their interpretation proposed Ar sorbcijas iekārtu Autosorb-1 (Quantochrome Instruments Co, Florida, USA) pētīta termiski eksfoliēta grafīta slāpekļa sorbcijas spēja salīdzinājumā ar citu oglekļa struktūru sorbciju tādos pašos apstākļos. Atrasti divi izotermu rajoni, kas raksturojas ar mazu (SBET1) un palielinātu (SBET2) īpatnējo virsmu.. Šāda veida izotermas raksturīgas slikti adsorbējošiem materiāliem, pie kādiem pieder arī akvadags. Labi adsorbējošās oglekļa struktūrām, tādām kā aktīvā ogle un oglekļa nanocaurules, raksturīgas cita veida izotermas. Apspriesta eksperimentālā rezultāta interpretācija

  8. The Starburst-AGN connection: quenching the fire and feeding the monster

    NASA Astrophysics Data System (ADS)

    Melnick, Jorge; Telles, Eduardo; De Propris, Roberto; Chu, Zhang-Hu

    2015-10-01

    The merger of two spiral galaxies is believed to be one of the main channels for the production of elliptical and early-type galaxies. In the process, the system becomes an (ultra) luminous infrared galaxy, or (U)LIRG, that morphs to a quasar, to a K+A galaxy, and finally to an early-type galaxy. The time scales for this metamorphosis are only loosely constrained by observations. In particular, the K+A phase should follow immediately after the quasi stellar object (QSO) phase during which the dust and gas remaining from the (U)LIRG phase are expelled by the active galactic nucleus (AGN). An intermediate class of QSOs with K+A spectral signatures, the post-starburst QSOs (PSQ), may represent the transitional phase between QSOs and K+As. We have compiled a sample of 72 bona fide z < 0.5 PSQ from the SDSS DR7 QSO catalogue. We find the intermediate age populations in this sample to be on average significantly weaker and metal poorer than their putative descendants, the K+A galaxies. The typical spectral energy distribution of PSQ is well fitted by three components: starlight; an obscured power-law; and a hot dust component required to reproduce the mid-IR fluxes. From the slope and bolometric luminosity of the power-law component we estimate typical masses and accretion rates of the AGN, but we find little evidence of powerful radio-loud or strong X-ray emitters in our sample. This may indicate that the power-law component originates in a nuclear starburst rather than in an AGN, as expected if the bulk of their young stars are still being formed, or that the AGN is still heavily enshrouded in dust and gas. We find that both alternatives are problematic and that more and better optical, X-ray, and mm-wave observations are needed to elucidate the evolutionary history of PSQ.

  9. Molecular mechanisms for generating transmembrane proton gradients

    PubMed Central

    Gunner, M.R.; Amin, Muhamed; Zhu, Xuyu; Lu, Jianxun

    2013-01-01

    Membrane proteins use the energy of light or high energy substrates to build a transmembrane proton gradient through a series of reactions leading to proton release into the lower pH compartment (P-side) and proton uptake from the higher pH compartment (N-side). This review considers how the proton affinity of the substrates, cofactors and amino acids are modified in four proteins to drive proton transfers. Bacterial reaction centers (RCs) and photosystem II (PSII) carry out redox chemistry with the species to be oxidized on the P-side while reduction occurs on the N-side of the membrane. Terminal redox cofactors are used which have pKas that are strongly dependent on their redox state, so that protons are lost on oxidation and gained on reduction. Bacteriorhodopsin is a true proton pump. Light activation triggers trans to cis isomerization of a bound retinal. Strong electrostatic interactions within clusters of amino acids are modified by the conformational changes initiated by retinal motion leading to changes in proton affinity, driving transmembrane proton transfer. Cytochrome c oxidase (CcO) catalyzes the reduction of O2 to water. The protons needed for chemistry are bound from the N-side. The reduction chemistry also drives proton pumping from N- to P-side. Overall, in CcO the uptake of 4 electrons to reduce O2 transports 8 charges across the membrane, with each reduction fully coupled to removal of two protons from the N-side, the delivery of one for chemistry and transport of the other to the P-side. PMID:23507617

  10. Detecting Novel Genetic Variants Associated with Isoniazid-Resistant Mycobacterium tuberculosis

    PubMed Central

    Chan, Maurice K. L.; Ong, Danny C. T.; Tongyoo, Pumipat; Wong, Sin-Yew; Lee, Ann S. G.

    2014-01-01

    Background Isoniazid (INH) is a highly effective antibiotic central for the treatment of Mycobacterium tuberculosis (MTB). INH-resistant MTB clinical isolates are frequently mutated in the katG gene and the inhA promoter region, but 10 to 37% of INH-resistant clinical isolates have no detectable alterations in currently known gene targets associated with INH-resistance. We aimed to identify novel genes associated with INH-resistance in these latter isolates. Methodology/Principal Findings INH-resistant clinical isolates of MTB were pre-screened for mutations in the katG, inhA, kasA and ndh genes and the regulatory regions of inhA and ahpC. Twelve INH-resistant isolates with no mutations, and 17 INH-susceptible MTB isolates were subjected to whole genome sequencing. Phylogenetically related variants and synonymous mutations were excluded and further analysis revealed mutations in 60 genes and 4 intergenic regions associated with INH-resistance. Sanger sequencing verification of 45 genes confirmed that mutations in 40 genes were observed only in INH-resistant isolates and not in INH-susceptible isolates. The ratios of non-synonymous to synonymous mutations (dN/dS ratio) for the INH-resistance associated mutations identified in this study were 1.234 for INH-resistant and 0.654 for INH-susceptible isolates, strongly suggesting that these mutations are indeed associated with INH-resistance. Conclusion The discovery of novel targets associated with INH-resistance described in this study may potentially be important for the development of improved molecular detection strategies. PMID:25025225

  11. Biorefinery Technologies for Biomass Conversion Into Chemicals and Fuels Towards Zero Emissions (Review) / Nulles Emisiju Princips Biomasas Konversijas Tehnoloģijās Aizstājot Fosilos Resursus (Pārskata Raksts)

    NASA Astrophysics Data System (ADS)

    Gravitis, J.; Abolins, J.

    2013-10-01

    Exhausting of world resources, increasing pollution, and climate change are compelling the shift of the world economy from continuous growth to a kind of economy based on integration of technologies into zero emissions production systems. Transition from non-renewable fossil resources to renewable resources provided by solar radiation and the current processes in biosphere is seen in the bio-refinery approach - replacing crude oil refineries by biomass refineries. Biotechnology and nano-technologies are getting accepted as important players along with conventional biomass refinery technologies. Systems design is a significant element in the integration of bio-refinery technologies in clusters. A number of case-studies, steam explosion auto-hydrolysis (SEA) in particular, are reviewed to demonstrate conversion of biomass into value-added chemicals and fuels. Analysis of energy flows is made as part of modelling the SEA processes, the eMergy (energy memory) approach and sustainability indices being applied to assess environmental impacts. Resursu izsīkums, vides piesārņojums un globāla mēroga klimatiskās izmaiņas ir civilizācijas izdzīvošanai būtiski faktori, kas virza pasaules ekonomikas pārmaiņas, atsakoties no nepārtrauktas izaugsmes idejas par labu tādai ekonomikai, kas balstās uz atjaunojošamies resursiem un dažādu tehnoloģiju integrācijemisiju principam atbilstošās ražošanas sistēmās. Saules radiācijas ierosinātajos planētas biosfērā notiekošajos procesos radīto organisko vielu pārstrādes kompleksi, kas operē ievērojot sabalansētu nulles emisiju principu, tiek uzlūkoti kā tās ekonomiskās (ražošanas) struktūras, kurām jānodrošina pāreja uz atjaunojošos resursu izmantošanu, aizstājot esošās fosilo resursu (naftas, ogļu) pārstrādes rūpnīcas. Līdzās jau apgūtajām biomasas rafinēšanas tehnoloģijām svarīga un pieaugoša loma ekonomiskās sistēmas resursu bāzes nomaiņā ir bio- un nanotehnolo

  12. Chromophore Poling in Thin Films of Organic Glasses. 3. Setup for Corona Triode Discharge / Hromoforu Polarizēšana Plānās Organisko Stiklu Kārtiņās 3. Koronas Izlādes Triodes Ierīce

    NASA Astrophysics Data System (ADS)

    Vilitis, O.; Titavs, E.; Nitiss, E.; Rutkis, M.

    2013-02-01

    The corona discharge is described focusing on the advantages of corona triode techniques for the direct current (DC) positive poling of optical polymers. The proposed experimental setup allows the corona poling of nonlinear optical (NLO) polymers in the modes of DC constant current (the lowest 1nA) and of the fixed corona-grid voltage, making it possible to carry out the corona-onset poling at elevated temperature (COPET) up to 200 oC. The setup also provides a wide range of the corona discharge voltage (3 kV - 15 kV), variable reciprocal distance of electrodes as well as the possibility to choose from different types of the corona electrode (needle, multi-needle, wire, etc.). By keeping the corona-to-grid voltage constant, a stable corona discharge at electrode is attained. The grid voltage can be varied in the range from 0 to 3kV. The corona poling area on the sample surface is pre-defined by placing ring spacers above it. The setup is completely computerized, allowing both control and monitoring of the corona discharge, which promotes research into the process of charging NLO polymer samples and selection of the optimal poling mode. Using the voltage-current characteristics and the second-harmonic measurements of a poled polymer we also demonstrate the influence of the setup parameters on the efficiency of poling the thin film NLO polymers. Darba ievadā īsumā aprakstīta koronas izlāde, izceļot koronas triodes theniskās metodes lietošanas priekšrocības optisko polimeru polarizēšanā ar pozitīvās koronas līdzstrāvu. Rakstā apskatīta eksperimentāla koronas polēšanas ierīce, kas sniedz iespēju polarizēt nelineāros optiskos (NLO) polimērus pie konstantas strāvas (līdz pat 1 nA) un fiksēta koronas elektroda-tīkliņa sprieguma, ļaujot veikt polēšanu paaugstinātās temperatūrās līdz 200 oC. Ierīcē paredzētas plašas koronas izlādes sprieguma izvēles robežas (3-15 kV), iespējas mainīt elektrodu savstarpējo izvietojumu un izv

  13. Development and Experimental Study of Phantoms for Mapping Skin Chromophores

    NASA Astrophysics Data System (ADS)

    Silapetere, A.; Spigulis, J.; Saknite, I.

    2014-06-01

    Skin chromophore phantoms are widely used for better understanding of the light interaction with tissue and for calibration of skin diagnostic imaging techniques. In this work, different phantoms were examined and compared in order to find biologically equivalent substances that are the most promising for this purpose. For mimicking the skin medium and layered structure, a fibrin matrix with epidermal and dermal cell inclusion was used. Synthesized bilirubin, red blood cells and nigrosin were taken as absorbers. For spectral analysis of the developed phantoms a computer-aided multispectral imaging system Nuance 2.4 (Cambridge Research & Instrumentation, Inc., USA) was used. In this study, skin phantoms were created using such substances as bilirubin, melanin, haemoglobin and nigrosin Mūsdienās multispektrālās attēlošanas iekārtas izmanto ādas parametru un fizioloģisko procesu aprakstīšanai gan pētniecības, gan diagnostikas nolūkiem. Iekārtu darbības uzlabošanai ir nepieciešams labāk saprast gaismas mijiedarbību ar audiem, kā arī veikt šo iekārtu kalibrēšanu ar ādas maketu. Redzamā un tuvā infrasarkanā optiskā diapazona spektroskopijā ir svarīgi ādas maketi, kas simulē audu slāņaino struktūru un ķīmiskās īpašības, kā arī maketi, kas ir bioloģiski līdzvērtīgi. Šajā pētījumā tika izveidots ādas makets no bioloģiskām un ķīmiski sintezētām struktūrām. Ādas maketa izveidei tika izmantota fibrīna matrica ar dermālo un epidermālo šūnu piejaukumu, lai imitētu ādas slāņaino struktūru. Fibrīna matrica tiek veidota no 0,47 ml asins plazmas, 0,4 ml fizioloģiskā šķīduma, 0,8 μl treneksāmskābes un 89,4 μl kalcija glukanāta. Izveidoto matricu ievieto šūnu inkubatorā, lai tā polimerizētos. Nākošais slānis tiek veidots ar dermālo šūnu piejaukumu (180-270 šūnas), un pēdējais fibrīna matriksa slānis tiek veidots ar epidermālo šūnu piejaukumu (270 šūnas) un šūnu aug

  14. Domain analysis of 3 Keto Acyl-CoA synthase for structural variations in Vitis vinifera and Oryza brachyantha using comparative modelling.

    PubMed

    Sagar, Mamta; Pandey, Neetesh; Qamar, Naseha; Singh, Brijendra; Shukla, Akanksha

    2015-03-01

    The long chain fatty acids incorporated into plant lipids are derived from the iterative addition of C2 units which is provided by malonyl-CoA to an acyl-CoA after interactions with 3-ketoacyl-CoA synthase (KCS), found in several plants. This study provides functional characterization of three 3 ketoacyl CoA synthase like proteins in Vitis vinifera (one) and Oryza brachyantha (two proteins). Sequence analysis reveals that protein of Oryza brachyantha shows 96% similarity to a hypothetical protein in Sorghum bicolor; total 11 homologs were predicted in Sorghum bicolor. Conserved domain prediction confirm the presence of FAE1/Type III polyketide synthase-like protein, Thiolase-like, subgroup; Thiolase-like and 3-Oxoacyl-ACP synthase III, C-terminal and chalcone synthase like domain but very long chain 3-keto acyl CoA domain is absent. All three proteins were found to have Chalcone and stilbene synthases C terminal domain which is similar to domain of thiolase and β keto acyl synthase. Its N terminal domain is absent in J3M9Z7 protein of Oryza brachyantha and F6HH63 protein of Vitis vinifera. Differences in N-terminal domain is responsible for distinguish activity. The J3MF16 protein of Oryza brachyantha contains N terminal domain and C terminal domain and characterized using annotation of these domains. Domains Gcs (streptomyces coelicolor) and Chalcone-stilbene synthases (KAS) in 2-pyrone synthase (Gerbera hybrid) and chalcone synthase 2 (Medicago sativa) were found to be present in three proteins. This similarity points toward anthocyanin biosynthetic process. Similarity to chalcone synthase 2 reveals its possible role in Naringenine and Chalcone synthase like activity. In 3 keto acyl CoA synthase of Oryza brachyantha. Active site residues C-240, H-407, N-447 are present in J3MF16 protein that are common in these three protein at different positions. Structural variations among dimer interface, product binding site, malonyl-CoA binding sites, were predicted in

  15. Toward Quantitatively Accurate Calculation of the Redox-Associated Acid–Base and Ligand Binding Equilibria of Aquacobalamin

    SciTech Connect

    Johnston, Ryne C.; Zhou, Jing; Smith, Jeremy C.; Parks, Jerry M.

    2016-07-08

    In redox processes in complex transition metal-containing species are often intimately associated with changes in ligand protonation states and metal coordination number. Moreover, a major challenge is therefore to develop consistent computational approaches for computing pH-dependent redox and ligand dissociation properties of organometallic species. Reduction of the Co center in the vitamin B12 derivative aquacobalamin can be accompanied by ligand dissociation, protonation, or both, making these properties difficult to compute accurately. We examine this challenge here by using density functional theory and continuum solvation to compute Co ligand binding equilibrium constants (Kon/off), pKas and reduction potentials for models of aquacobalamin in aqueous solution. We consider two models for cobalamin ligand coordination: the first follows the hexa, penta, tetra coordination scheme for CoIII, CoII, and CoI species, respectively, and the second model features saturation of each vacant axial coordination site on CoII and CoI species with a single, explicit water molecule to maintain six directly interacting ligands or water molecules in each oxidation state. Comparing these two coordination schemes in combination with five dispersion-corrected density functionals, we find that the accuracy of the computed properties is largely independent of the scheme used, but including only a continuum representation of the solvent yields marginally better results than saturating the first solvation shell around Co throughout. PBE performs best, displaying balanced accuracy and superior performance overall, with RMS errors of 80 mV for seven reduction potentials, 2.0 log units for five pKas and 2.3 log units for two log Kon/off values for the aquacobalamin system. Furthermore, we find that the BP86 functional commonly used in corrinoid studies suffers from erratic behavior and inaccurate descriptions of

  16. Charging of the Electric Vehicles in Private Sector: Technical and Economic Aspects

    NASA Astrophysics Data System (ADS)

    Grackova, L.; Oleinikova, I.; Klavs, G.

    2014-12-01

    The economic aspect considered in the work is related to the charging of an electric vehicle (EV) at a single private house when this is done every day. To perform the relevant cost estimation it was necessary to determine: the average annual electricity consumption under the condition of everyday charging an EV and the average electricity consumption off the mains for covering a distance of 100 km by an EV and the time in hours for its charging. Comparison is made for the day-time intervals from which it is possible to choose the preferable for proper loading the electric line and the most beneficial for the consumer. Under analysis are two EV connection scenarios for 100 individual households from which 10%, 20% and 30% have EVs, with 8-h duration of each charging at the current of 13A. The authors consider the consumption and electric energy payment packages which - with planned opening of the electric energy market on January 1, 2015 - will offer the clients the enterprises rendering services on the electric energy sale. Šajā rakstā tiek analizēts vidējais diennakts elektroenerģijas patēriņš un diennakts slodzes grafiki privātmājās apstākļos, kad privātmājas īpašnieki lādē elektroautomobili katru dienu vidējam brauciena attālumam 100 km. Elektroautomobiļa uzlādes režīmi tiek analizēti, ņemot vērā patēriņa elektriskās slodzes grafika kvalitāti raksturojošos rādītājus un patērētāja ekonomiskos ieguvumus. Lai novērtētu ekonomiski stimulētu patērētāju elektroautomobiļa uzlādes laika izvēles ietekmi uz diennakts elektriskās slodzes aizpildījuma koeficientu, tika izveidoti un analizēti 2 scenāriji, kas apraksta 100 privātmāju ar dažādu elektroautomobiļu piederības īpatsvaru divas atšķirīgas automobiļu uzlādes gadījumus.

  17. pH-dependent transitions in xanthorhodopsin.

    PubMed

    Imasheva, Eleonora S; Balashov, Sergei P; Wang, Jennifer M; Lanyi, Janos K

    2006-01-01

    Xanthorhodopsin (XR), the light-driven proton pump of the halophilic eubacterium Salinibacter ruber, exhibits substantial homology to bacteriorhodopsin (BR) of archaea and proteorhodopsin (PR) of marine bacteria, but unlike them contains a light-harvesting carotenoid antenna, salinixanthin, as well as retinal. We report here the pH-dependent properties of XR. The pKa of the retinal Schiff base is as high as in BR, i.e. > or =12.4. Deprotonation of the Schiff base and the ensuing alkaline denaturation cause large changes in the absorption bands of the carotenoid antenna, which lose intensity and become broader, making the spectrum similar to that of salinixanthin not bound to XR. A small redshift of the retinal chromophore band and increase of its extinction, as well as the pH-dependent amplitude of the M intermediate indicate that in detergent-solubilized XR the pKa of the Schiff base counterion and proton acceptor is about 6 (compared to 2.6 in BR, and 7.5 in PR). The protonation of the counterion is accompanied by a small blueshift of the carotenoid absorption bands. The pigment is stable in the dark upon acidification to pH 2. At pH < 2 a transition to a blueshifted species absorbing around 440 nm occurs, accompanied by loss of resolution of the carotenoid absorption bands. At pH < 3 illumination of XR with continuous light causes accumulation of long-lived photoproduct(s) with an absorption maximum around 400 nm. The photocycle of XR was examined between pH 4 and 10 in solubilized samples. The pH dependence of recovery of the initial state slows at both acid and alkaline pH, with pKas of 6.0 and 9.3. The decrease in the rates with pKa 6.0 is apparently caused by protonation of the counterion and proton acceptor, and that at high pH reflects the pKa of the internal proton donor, Glu94, at the times in the photocycle when this group equilibrates with the bulk.

  18. Binding of Escherichia coli heat-stable enterotoxin to rat intestinal cells and brush border membranes.

    PubMed Central

    Frantz, J C; Jaso-Friedman, L; Robertson, D C

    1984-01-01

    The association of heat-stable enterotoxin (STa) produced by enterotoxigenic Escherichia coli 431 with isolated rat intestinal epithelial cells and brush border membranes was characterized. Specific binding of strain 431 125I-STa to a single class of specific high-affinity receptors was saturable and temperature dependent and reached a maximum between 5 and 10 min. A 1,000-fold excess of unlabeled 431 STa competitively displaced 90 to 95% of radiolabeled enterotoxin bound to brush border membranes. In contrast, specific binding of 431 125I-STa to intestinal cells ranged from 40 to 65%. The number of STa-specific receptors on rat intestinal cells determined by Scatchard analysis was 47,520 +/- 14,352 (mean +/- standard error of the mean) per cell, with affinity constants (KaS) of 2.55 X 10(11)and 4.32 x 10(11) liters/mol determined for intestinal cells and brush border membranes, respectively. Villus intestinal cells appeared to possess about twice as many STa receptors as did crypt cells. Dissociation of specifically bound 431 125I-STa from intestinal cells and brush border membranes was minimal (2 to 5%). In addition, neither the rate nor the extent of dissociation was increased by a 1,000-fold excess of unlabeled homologous 431 Sta. Binding experiments with 431 125I-STa and brush border membranes showed that purified unlabeled STas from enterotoxigenic E. coli strains 667 (class 1 porcine enteropathogen), B-41 (bovine enteropathogen), and human strains 213C2 (Mexico) and 153961-2 (Dacca, Bangledesh) exhibited patterns of competitive inhibition similar to those of homologous unlabeled 431 STa (class 2 enteropathogen). A lipid extract which contained gangliosides and glycolipids exhibited dose-dependent competitive inhibition of heat-labile enterotoxin binding to brush border membranes but did not inhibit binding of 431 125I-STa. Purified heat-labile enterotoxin from strain 286C2 did not inhibit binding of 431 STa to brush border membranes. Pronase treatment of

  19. Structural and dynamical aspects of Streptococcus gordonii FabH through molecular docking and MD simulations.

    PubMed

    Shamim, Amen; Abbasi, Sumra Wajid; Azam, Syed Sikander

    2015-07-01

    β-Ketoacyl-ACP-synthase III (FabH or KAS III) has become an attractive target for the development of new antibacterial agents which can overcome the multidrug resistance. Unraveling the fatty acid biosynthesis (FAB) metabolic pathway and understanding structural coordinates of FabH will provide valuable insights to target Streptococcus gordonii for curing oral infection. In this study, we designed inhibitors against therapeutic target FabH, in order to block the FAB pathway. As compared to other targets, FabH has more interactions with other proteins, located on the leading strand with higher codon adaptation index value and associated with lipid metabolism category of COG. Current study aims to gain in silico insights into the structural and dynamical aspect of S. gordonii FabH via molecular docking and molecular dynamics (MD) simulations. The FabH protein is catalytically active in dimerization while it can lock in monomeric state. Current study highlights two residues Pro88 and Leu315 that are close to each other by dimerization. The active site of FabH is composed of the catalytic triad formed by residues Cys112, His249, and Asn279 in which Cys112 is involved in acetyl transfer, while His249 and Asn279 play an active role in decarboxylation. Docking analysis revealed that among the studied compounds, methyl-CoA disulfide has highest GOLD score (82.75), binding affinity (-11 kcal/mol) and exhibited consistently better interactions. During MD simulations, the FabH structure remained stable with the average RMSD value of 1.7 Å and 1.6 Å for undocked protein and docked complex, respectively. Further, crucial hydrogen bonding of the conserved catalytic triad for exhibiting high affinity between the FabH protein and ligand is observed by RDF analysis. The MD simulation results clearly demonstrated that binding of the inhibitor with S. gordonii FabH enhanced the structure and stabilized the dimeric FabH protein. Therefore, the inhibitor has the potential to become

  20. Conserved mechanism of PLAG1 activation in salivary gland tumors with and without chromosome 8q12 abnormalities: identification of SII as a new fusion partner gene.

    PubMed

    Aström, A K; Voz, M L; Kas, K; Röijer, E; Wedell, B; Mandahl, N; Van de Ven, W; Mark, J; Stenman, G

    1999-02-15

    We have previously shown (K. Kas et al, Nat. Genet., 15: 170-174, 1997) that the developmentally regulated zinc finger gene pleomorphic adenoma gene 1 (PLAG1) is the target gene in 8q12 in pleomorphic adenomas of the salivary glands with t(3;8)(p21;q12) translocations. The t(3;8) results in promoter swapping between PLAG1 and the constitutively expressed gene for beta-catenin (CTNNB1), leading to activation of PLAG1 expression and reduced expression of CTNNB1. Here we have studied the expression of PLAG1 by Northern blot analysis in 47 primary benign and malignant human tumors with or without cytogenetic abnormalities of 8q12. Overexpression of PLAG1 was found in 23 tumors (49%). Thirteen of 17 pleomorphic adenomas with a normal karyotype and 5 of 10 with 12q13-15 abnormalities overexpressed PLAG1, which demonstrates that PLAG1 activation is a frequent event in adenomas irrespective of karyotype. In contrast, PLAG1 was overexpressed in only 2 of 11 malignant salivary gland tumors analyzed, which suggests that, at least in salivary gland tumors, PLAG1 activation preferentially occurs in benign tumors. PLAG1 over-expression was also found in three of nine mesenchymal tumors, i.e., in two uterine leiomyomas and one leiomyosarcoma. RNase protection, rapid amplification of 5'-cDNA ends (5'-RACE), and reverse transcription-PCR analyses of five adenomas with a normal karyotype revealed fusion transcripts in three tumors. Nucleotide sequence analysis of these showed that they contained fusions between PLAG1 and CTNNB1 (one case) or PLAG1 and a novel fusion partner gene, i.e., the gene encoding the transcription elongation factor SII (two cases). The fusions occurred in the 5' noncoding region of PLAG1, leading to exchange of regulatory control elements and, as a consequence, activation of PLAG1 gene expression. Because all of the cases had grossly normal karyotypes, the rearrangements must result from cryptic rearrangements. The results suggest that in addition to

  1. Progresses in Ab Initio QM/MM Free Energy Simulations of Electrostatic Energies in Proteins: Accelerated QM/MM Studies of pKa, Redox Reactions and Solvation Free Energies

    SciTech Connect

    Kamerlin, Shina C. L.; Haranczyk, Maciej; Warshel, Arieh

    2009-03-01

    Hybrid quantum mechanical / molecular mechanical (QM/MM) approaches have been used to provide a general scheme for chemical reactions in proteins. However, such approaches still present a major challenge to computational chemists, not only because of the need for very large computer time in order to evaluate the QM energy but also because of the need for propercomputational sampling. This review focuses on the sampling issue in QM/MM evaluations of electrostatic energies in proteins. We chose this example since electrostatic energies play a major role in controlling the function of proteins and are key to the structure-function correlation of biological molecules. Thus, the correct treatment of electrostatics is essential for the accurate simulation of biological systems. Although we will be presenting here different types of QM/MM calculations of electrostatic energies (and related properties), our focus will be on pKa calculations. This reflects the fact that pKa of ionizable groups in proteins provide one of the most direct benchmarks for the accuracy of electrostatic models of macromolecules. While pKa calculations by semimacroscopic models have given reasonable results in many cases, existing attempts to perform pKa calculations using QM/MM-FEP have led to large discrepancies between calculated and experimental values. In this work, we accelerate our QM/MM calculations using an updated mean charge distribution and a classical reference potential. We examine both a surface residue (Asp3) of the bovine pancreatic trypsin inhibitor, as well as a residue buried in a hydrophobic pocket (Lys102) of the T4-lysozyme mutant. We demonstrate that by using this approach, we are able to reproduce the relevant sidechain pKas with an accuracy of 3 kcal/mol. This is well within the 7 kcal/mol energy difference observed in studies of enzymatic catalysis, and is thus sufficient accuracy to determine the main contributions to the catalytic energies of enzymes. We also provide an

  2. Advanced Concept for Creation of Security Holograms / PROGRESĪVĀ Koncepcija AIZSARDZĪBAS Hologrammas Izveidei

    NASA Astrophysics Data System (ADS)

    Bulanovs, A.; Gerbreders, S.

    2013-12-01

    A new concept is proposed for digital hologram production along with the relevant techniques developed in our laboratory. The main idea of the concept is to maximally separate the calculation of hologram from its optical recording on the light-sensitive media. A special file format containing information on each holographic pixel is created at the stage of calculation. The file is a device-independent by structure, and can be employed for recording a hologram using any of the existing techniques (dot-matrix, optical matrix lithography, e-beam lithography). An optical lithography device is applied to calculate the images for a spatial light modulator at the stage of hologram recording in accordance with the data from the file and in conformity with the hardware features of the device. The proposed method was tested and successfully used to record security holograms. For commercial use a software package and an optical recording system have been developed. Šajā rakstā tiek apskatītas koncepcijas un metodes, kuras tiek izmantotas drošības hologrammu ražošanai mūsu laboratorijā. Koncepcijas galvenā ideja ir hologrammas aprēķina posmu maksimālais sadalījums no hologrammu optiskā ieraksta uz gaismas jūtīgām vidēm. Hologrammas aprēķina posmā tiek izveidots īpaša formāta fails, kas satur pilnu informāciju par katru hologrāfisko pikseli. Pēc struktūras fails ir neatkarīgs no ierīces un to var izmantot hologrammas ierakstam pēc jebkuras no esošajām tehnoloģijām. Hologrammas ieraksta posmā optiskā litogrāfijas iekārta pēc faila datiem veic SLM (Spatial Light Modulator) attēla aprēķinu, ievērojot iekārtas darbības īpatnības. Piedāvātā metode ir pārbaudīta un veiksmīgi tiek izmantota drošības hologrammu ierakstam. Izstrādāta programmu pakete un optiskā ieraksta iekārta komerciālai izmantošanai.

  3. Toward Quantitatively Accurate Calculation of the Redox-Associated Acid–Base and Ligand Binding Equilibria of Aquacobalamin

    SciTech Connect

    Johnston, Ryne C.; Zhou, Jing; Smith, Jeremy C.; Parks, Jerry M.

    2016-07-08

    In redox processes in complex transition metal-containing species are often intimately associated with changes in ligand protonation states and metal coordination number. Moreover, a major challenge is therefore to develop consistent computational approaches for computing pH-dependent redox and ligand dissociation properties of organometallic species. Reduction of the Co center in the vitamin B12 derivative aquacobalamin can be accompanied by ligand dissociation, protonation, or both, making these properties difficult to compute accurately. We examine this challenge here by using density functional theory and continuum solvation to compute Co ligand binding equilibrium constants (Kon/off), pKas and reduction potentials for models of aquacobalamin in aqueous solution. We consider two models for cobalamin ligand coordination: the first follows the hexa, penta, tetra coordination scheme for CoIII, CoII, and CoI species, respectively, and the second model features saturation of each vacant axial coordination site on CoII and CoI species with a single, explicit water molecule to maintain six directly interacting ligands or water molecules in each oxidation state. Comparing these two coordination schemes in combination with five dispersion-corrected density functionals, we find that the accuracy of the computed properties is largely independent of the scheme used, but including only a continuum representation of the solvent yields marginally better results than saturating the first solvation shell around Co throughout. PBE performs best, displaying balanced accuracy and superior performance overall, with RMS errors of 80 mV for seven reduction potentials, 2.0 log units for five pKas and 2.3 log units for two log Kon/off values for the aquacobalamin system. Furthermore, we find that the BP86 functional commonly used in corrinoid studies suffers from erratic behavior and inaccurate descriptions of

  4. Substituent Effects on Electrophilic Catalysis by the Carbonyl Group: Anatomy of the Rate Acceleration for PLP-Catalyzed Deprotonation of Glycine

    PubMed Central

    Crugeiras, Juan; Rios, Ana; Riveiros, Enrique; Richard, John P.

    2011-01-01

    First-order rate constants, determined by 1H NMR, are reported for deuterium exchange between solvent D2O and the α-amino carbon of glycine in the presence of increasing concentrations of carbonyl compounds (acetone, benzaldehyde and salicylaldehyde) and at different pD and buffer concentrations. These rate data were combined with 1H NMR data that define the position of the equilibrium for formation of imines/iminium ions from addition of glycine to the respective carbonyl compounds, to give second-order rate constants kDO for deprotonation of α-imino carbon by DO−. The assumption that these second-order rate constants lie on linear structure-reactivity correlations between log kOL and pKa was made in estimating the following pKas for deprotonation of α-imino carbon: pKa = 22, glycine–acetone iminium ion; pKa = 27, glycine–benzaldehyde imine; pKa ≈ 23, glycine–benzaldehyde iminium ion; and, pKa = 25, glycine–salicylaldehyde iminium ion. The much lower pKa of 17 [Toth, K.; Richard, J. P. J. Am. Chem. Soc. 2007, 129, 3013–3021] for carbon deprotonation of the adduct between 5′-deoxypyridoxal (DPL) and glycine shows that the strongly electron-withdrawing pyridinium ion is unique in driving the extended delocalization of negative charge from the α-iminium to the α-pyridinium carbon. This favors carbanion protonation at the α–pyridinium carbon, and catalysis of the 1,3-aza-allylic isomerization reaction that is a step in enzyme-catalyzed transamination reactions. An analysis of the effect of incremental changes in structure on the activity of benzaldehyde in catalysis of deprotonation of glycine shows the carbonyl group electrophile, the 2-O− ring substituent and the cation pyridinium nitrogen of DPL each make a significant contribution to the catalytic activity of this cofactor analog. The extraordinary activity of DPL in catalysis of deprotonation of α–amino carbon results from the summation of these three smaller effects. PMID:21323335

  5. Superdiffusion of Carbon by Vacancies Irradiated with Soft X-Rays in CZ Silicon / Superdifūzija Ar Vakancēm Iestarota Ar Mīkstajiem Rentgenstariem CZ Silīcijā

    NASA Astrophysics Data System (ADS)

    Janavičius, A. J.; Mekys, A.; Purlys, R.; Norgėla, Ž.; Daugėla, S.; Rinkūnas, R.

    2015-10-01

    The soft X-ray photons absorbed in the inner K, L, M shells of Si atoms produce photoelectrons and Auger electrons, thus generating vacancies, interstitials and metastable oxygen complexes. The samples of Czochralski silicon crystals covered with 0.1 μm thickness layer of carbon have been irradiated by X-rays using different voltages of Cu anode of the Russian diffractometer DRON-3M. The influence of X-rays on the formation of point defects and vacancy complexes, and their dynamics in Cz-Si crystals have been studied by infrared absorption. We have measured and calculated dynamics of concentration of carbon and interstitial oxygen using FTIR spectroscopy at room temperature after irradiation by soft X-rays. Using transmittance measurements and nonlinear diffusion theory we have calculated densities increasing for substitutional carbon and interstitial oxygen by reactions and very fast diffusion. The superdiffusion coefficients of carbon in silicon at room temperature generated by X-rays are about hundred thousand times greater than diffusion coefficients obtained for thermodiffusion. Rezumējums: Rentgena staru fotoni, absorbēti Si atoma iekšējos slāņos, izstaro fotoelektronus un Ožē elektronus, ģenerējot vakances, starpmezglu silīcija atomus, vakanču un skābekļa kompleksus. Čohraļska silīcija kristāli, kas pārklāti ar oglekli 0.1 μm biezuma kārtā, tika apstaroti ar rentgena stariem, izmantojot krievu difraktometru DRON-3M. Oglekļa un skābekļa difūzija un koncentrāciju izmaiņa silīcijā tika izmērīta izmantojot infrasarkano staru FTIR spektroskopiju. Rentgena staru ģenerētās ļoti ātrās oglekļa difūzijas vai superdifūzijas koeficients istabas temperatūrā silīcijā ir simtiem tūkstošu reižu lielāks nekā termodifūzijas gadījumā.

  6. Synthesis and Iron Sequestration Equilibria of Novel Exocyclic 3-Hydroxy-2-pyridinone Donor Group Siderophore Mimics

    PubMed Central

    Harrington, James M.; Chittamuru, Sumathi; Dhungana, Suraj; Jacobs, Hollie K.; Gopalan, Aravamudan S.; Crumbliss, Alvin L.

    2011-01-01

    The synthesis of a novel class of exocyclic bis- and tris-3,2-hydroxypyridinone (HOPO) chelators built on N2 and N3 aza-macrocyclic scaffolds and the thermodynamic solution characterization of their complexes with Fe(III) are described. The chelators for this study were prepared by reaction of either piperazine or N, N’, N”-1,4,7-triazacyclononane with a novel electrophilic HOPO iminium salt in good yields. Subsequent removal of the benzyl protecting groups using hydrogenolysis gave bis-HOPO chelators N2(etLH)2 and N2(prLH)2, and tris-HOPO chelator N3(etLH)3 in excellent yields. Solution thermodynamic characterization of their complexes with Fe(III) has been accomplished using spectrophotometric, potentiometric and ESI-MS methods. The pKas of N2(etLH)2, N2(prLH)2, and N3(etLH)3, were determined spectrophotometrically and potentiometrically. The Fe(III) complex stability constants for the tetradentate N2(etLH)2 and N2(prLH)2, and hexadentate N3(etLH)3, were measured by spectrophotometric and potentiometric titration, and by competition with EDTA. N3(etLH)3 forms a 1:1 complex with Fe(III) with log β110 = 27.34 ± 0.04. N2(prLH)2 forms a 3:2 L:Fe complex with Fe(III) where log β230 = 60.46 ± 0.04 and log β110 = 20.39 ± 0.02. While N2(etLH)2 also forms a 3:2 L:Fe complex with Fe(III), solubility problems precluded determining log β230; log β110 was found to be 20.45 ± 0.04. The pFe values of 26.5 for N3(etLH)3 and 24.78 for N2(prLH)2 are comparable to other siderophore molecules used in the treatment of iron overload, suggesting that these hydroxypyridinone ligands may be useful in the development of new chelation therapy agents. PMID:20715813

  7. Speciation of ferric phenoxide intermediates during the reduction of iron(III)-μ-oxo dimers by hydroquinone.

    PubMed

    Kerber, William D; Perez, Kaitlyn A; Ren, Chuqiao; Siegler, Maxime A

    2014-11-03

    The aqueous speciation of iron(III)-tris(pyridylmethyl)amine (TPA) complexes was determined from potentiometric titration data, and the overall formation constants (β) for relevant species were calculated. At pH < 3 the mononuclear complex [Fe(TPA)](+3)(aq) predominates (log β = 10.75(15). Above pH 3 Fe(3+)-OH2 hydrolysis produces the μ-oxo dimer [Fe2(μ-O)(TPA)2(H2O)2](+4) (1a; log β = 19.91(12)). This species is a diprotic acid with the conjugate bases [Fe2(μ-O)(TPA)2(H2O)(OH)](+3) (1b; log β = 15.53(6)) and [Fe2(μ-O)(TPA)2(OH)2](+2) (1c; log β = 10.27(7)). The pKas of 1a are 4.38(14) and 5.26(9). Compounds 1a-c quantitatively oxidize hydroquinone to benzoquinone with concomitant formation of 2 equiv of Fe(II). Kinetic and spectroscopic data at pH 5.6 are consistent with rapid equilibrium formation of a diiron(III)-phenoxide intermediate followed by rate-controlling electron transfer. The equilibrium constant for the formation of the intermediate complex is 25(3) M(-1), and the rate constant for its decomposition is 0.56(9) s(-1). A kinetic isotope effect of kH/kD = 1.5 was determined from proton inventory experiments in mixed H/D media. The μ-oxo-diiron(III) phenoxide intermediate is hydrolyzed in a pH dependent process to form a mononuclear iron(III)-phenoxide, which complicates the kinetics by introducing a fractional dependence on total iron(III) concentration in the pH range 4.1-5.2. The pH-dependent cleavage of μ-oxo-diiron(III)-phenoxides was investigated with phenol, a redox-inert proxy for hydroquinone. The addition of phenol to 1 facilitates acidic cleavage of the μ-oxo dimer to form [Fe(TPA)(OPh)(H2O)](+2), which becomes the dominant iron(III)-phenoxide as the pH decreases to 4. The 2-naphtholate analogue of this intermediate, [Fe(TPA)(2-naphtholate)(OCH3)]ClO4 (6), was characterized by single-crystal X-ray diffraction (C29H28FeN4O2,ClO4; P21; a = 13.2646(2) Å, b = 15.2234(3) Å, c = 13.7942(3) Å; Z = 4).

  8. Lietuvos erdvinės informacijos sklaidos galimybės ir perspektyvos

    NASA Astrophysics Data System (ADS)

    Beconytė, Giedrė; Papšienė, Lina; Kryžanauskas, Audrius

    2010-01-01

    Padidėjęs erdvinių duomenų ir jų naudojimo poreikis paskatino kurti erdvinių duomenų infrastruktūras, leidžiančias teikti erdvinius duomenis aprašančią informaciją bei pačius duomenis iš įvairių šaltinių, nepriklausomai kur jie bebūtų bei duomenų formato ar struktūros. Lietuvoje dauguma erdvinių duomenų rinkinių "izoliuoti", o informacija apie juos sunkiai prieinama, todėl buvo siekiama sukurti modernią visą šalį apimančią vieną viešojo sektoriaus erdvinių duomenų paie\\vskos ir perdavimo sistemą. 2009 m. buvo sukurta Lietuvos erdvinės informacijos infrastruktūra (LEII), suteikianti priemones užtikrinti nacionalinių erdvinių duomenų pasiekiamumą ir teikimą internetu naudotojams jiems priimtinu būdu. Pagrindinis Europos Bendrijos erdvinės informacijos infrastruktūros (INSPIRE) kūrimo tikslas - pasiekti visų Bendrijos narių erdvinės informacijos suderinamumą. Įvairiose šalyse duomenų kaupimo, tvarkymo ir teikimo praktika skirtinga, todėl yra kuriamos bendros, vienijančios INSPIRE temų erdvinių duomenų rinkinių specifikacijos. Europos Bendrijos narės bus įpareigotos teikti duomenis INSPIRE laikantis šių specifkacijų, todėl atsiras galimybė iš skirtingų Europos Bendrijos valstybių gautus erdvinius duomenis sujungti ir naudoti kaip bendrus. Sukūrus LEII, Lietuvoje technologi\\vskai pasirengta teikti erdvinius duomenis bei yra sukaupti 56 oficialių duomenų rinkiniai, atitinkantys INSPIRE temas. Nors kol kas visi duomenų rinkiniai ne visi\\vskai atitinka patvirtintąsias specifikacijas, taikant Lietuvos erdvinės informacijos infrastruktūros technologijas, duomenis galima transformuoti į reikiamą struktūrą teikimo proceso metu.

  9. Potential of the Lower Daugava for Siting Hydrokinetic Turbines / Daugavas Lejteces Enerģētiskais Potenciāls Hidrokinētisko Turbīnu Izmantošanai

    NASA Astrophysics Data System (ADS)

    Kalnach, A.; Kalnach, J.; Mutule, A.; Persis, U.

    2013-04-01

    The article outlines the requirements and criteria for the hydrokinetic turbine site and determines the water flow characteristics based on which the energy potential of such a turbine is calculated for lower reaches of the River Daugava. The changes in the energy potential caused by fluctuations in the water density and flow rate are evaluated. Two investigated spans (total > 22 km) are split into ten smaller subregions with similar characteristics and comparatively evaluated regarding their suitability for electricity generation by hydrokinetic turbines. Īsumā rakstā apskatītās tēmas var rezumēt sekojoši: 1. Aprakstīti iegūtie dati un secinājumi par Daugavas lejteces straumes ātrumiem, kas var tikt izmantoti elektrostaciju, kuras darbina hidrokinētiskās turbīnas, ierīkošanai. Izvērtēts hidrokinētisko turbīnu izmantošanas enerģētiskais potenciāls Daugavas lejtecē (vairāk nekā 22 km upes garuma). 2. Aprakstītas un pamatotas atrastās iespējamās vietas dažādu atsevišķu hidrokinētisko turbīnu un to parku uzstādīšanai. 3. Darba rezultāti ļauj aptuveni novērtēt arī citu Daugavas tuvāko posmu potenciālu hidrokinētisko turbīnu izmantošanai tuvākā un tālākā nākotnē, kad hidrokinētisko turbīnu tehnoloģijas attīstīsies, dodot iespēju ražot elektroenerģiju pie zemākiem straumju ātrumiem.

  10. The Marocche rock avalanches (Trentino, Italy)

    NASA Astrophysics Data System (ADS)

    Ivy-Ochs, Susan; Martin, Silvana; Campedel, Paolo; Viganò, Alfio; Alberti, Silvio; Rigo, Manuel; Vockenhuber, Christof

    2015-04-01

    The floors of the Adige and Sarca River valleys are punctuated by numerous rock avalanche deposits of undetermined age. With a view to understanding predisposition and triggering factors, thus ultimately paleoseismicity in the region, we are studying the geomorphology and timing of the largest rock avalanches of the River Sarca-Lake Garda area (e.g., Marocche, Monte Spinale, Lago di Tovel, Lago di Molveno, San Giovanni and Torbole). Among the most extensive of these deposits, with an area of 13 km2 and a volume of about 109 m3, are the Marocche. Marocche deposits cover the lower Sarca valley north of Lake Garda for a length of more than 8 km with 200 m of debris. Both collapse and bedding parallel sliding are a consequence of dip slopes and the extreme relief on the right side of the valley of nearly 2000 m from the bedrock below the valley floor to the peaks combined with the zones of structural weakness. The rock avalanches developed within carbonate rocks of Mesozoic age, mainly limestones of the Jurassic Calcari Grigi Group. The main scarps are located on the western side of the lower Sarca Valley, along the steep faces of Mt. Brento and Mt. Casale. The presence of these scarps is strictly related to the Southern Giudicarie and the Ballino fault systems. The former is here constituted by regular NNE-directed ESE-vergent thrust faults. The latter has been reactivated as normal faults. These complicated structural relationships favored complex failure mechanisms, including rock slide and massive collapse. At the Marocche itself, based on field relationships and analysis of lidar imagery, we differentiated two large rock avalanches: the Marocca di Kas in the south which overlies and in part buries the Marocche (s.s.) in the northern sector. Previous mapping had suggested up to five rock avalanches in the area where we differentiate two. In spite of hypotheses suggesting failure of the rock avalanches onto stagnating late Pleistocene glaciers, preliminary 36Cl

  11. pH-metric log P. II: Refinement of partition coefficients and ionization constants of multiprotic substances.

    PubMed

    Avdeef, A

    1993-02-01

    A generalized, weighted, nonlinear least squares procedure is developed, based on pH titration data, for the refinement of octanol-water partition coefficients (log P) and ionization constants (pKa) of multiprotic substances. Ion-pair partition reactions, self-association reactions forming oligomers, and formations of mixed-substance complexes can be treated with this procedure. The procedure allows for CO2 corrections in instances where the base titrant may have CO2 as an impurity. Optionally, the substance purity and the titrant strength may be treated as adjustable parameters. The partial differentiation in the Gauss-Newton refinement procedure is based on newly derived analytical expressions. The new procedure was experimentally demonstrated with benzoic acid, 1-benzylimidazole, (+/-)-propranolol, and mellitic acid (benzenehexacarboxylic acid, AH6). Ionic strength (l) was adjusted with KNO3. Benzoic acid (20 degrees C; l 0.1 M): pKa = 3.99 +/- 0.02, log P = 1.96 +/- 0.02, log P (anion) = -1.2; 1-benzylimidazole (25 degrees C; l 0.1 M): pKa = 6.70 +/- 0.03, log P = 1.60 +/- 0.04; propranolol (25 degrees C; l 0.1 M): pKa = 9.53 +/- 0.06, log P = 3.35 +/- 0.03, log P (cation) = 0.62 +/- 0.08; mellitic acid (26 degrees C; l 0.2 M): pKas 1.10 +/- 0.46, 1.69 +/- 0.03, 2.75 +/- 0.02, 4.00 +/- 0.02, 5.05 +/- 0.01, and 6.04 +/- 0.02; in the presence of 0.01 M n-Bu4NBr, log P (AH6) = 1.5, log P (AH5-) = 1.1, log P (AH4(2-)) = 0.8, log P (AH3(3-)) = 0.3, log P (AH2(4-)) = -0.1, and log P (AH5-) = -0.5 (all +/- 0.1).(ABSTRACT TRUNCATED AT 250 WORDS)

  12. PA/p Ka equalization and the prediction of the hydrogen-bond strength: A synergism of classical thermodynamics and structural crystallography

    NASA Astrophysics Data System (ADS)

    Gilli, Paola; Pretto, Loretta; Gilli, Gastone

    2007-11-01

    geometries and Δp Kas, the p Ka differences between H-bond donor and acceptor groups, can deal with these three classes of bonds at the same time and has, therefore, the chance to become the method of election for a quick and reasonably accurate prediction of H-bond strengths based on thermodynamic acid-base indicators.

  13. Syntheses of new imidazole ligand series and evaluation of 1-, 2- and 4,5-imidazole substituent electronic and steric effects on N-donor strengths

    NASA Astrophysics Data System (ADS)

    Eseola, Abiodun O.; Sun, Wen-Hua; Li, Wen; Woods, Joseph A. O.

    2010-12-01

    A series of new imidazole based heterocycles (5-(4,5-diphenyl-1H-imidazol-2-yl)furan-2-yl)methyl acetate ( Him-dp), (5-(1H-phenanthro[9,10-d]imidazol-2-yl)furan-2-yl)methyl acetate ( HIm-pt), (5-(1H-imidazo[4,5-f][1,10]phenanthrolin-2-yl)furan-2-yl)methyl acetate ( HIm-phen), 2-(2-nitrophenyl)-4,5-diphenyl-1H-imidazole ( HIm-n), 1-methyl-2-(2-nitrophenyl)-4,5-diphenyl-1H-imidazole ( MeIm-n), N-(2-(1-ethyl-4,5-diphenyl-1H-imidazol-2-yl)phenyl)benzamide ( EtIm-ba) and 2,4-di-tert-butyl-6-(8-(1-ethyl-4,5-diphenyl-1H-imidazol-2-yl)-1,4-dihydroquinolin-2-yl)phenol ( EtIm-q) were synthesized and studied for the dependence of their azole donor characteristics on substituent factors by means of experimentally determined ionization constant data (derived as p Kas), spectroscopic analyses and calculated properties of their DFT optimized molecular geometries performed at the B3LYP/6-311 + G * level. Results showed that the lowest donor strength recorded for HIm-pt (p Ka = 2.67 ± 0.07) could be traced to the extensive electronic conjugation of the azole π-electrons with 4,5- and 2-substituents. On the other hand, the strongest imidazole donor strength in the series was obtained from EtIm-q (p Ka = 4.61 ± 0.04) for which the substituents possessed negligible π-overlap with the azole ring. The experimental results and theoretical calculations lead to conclusions that effective conjugation between the imidazole ring and substituent aromatic groups is accountable for significant withdrawal of charge densities on the imidazole N-donor atom and vice versa. Furthermore, observed donor strengths in the series suggest that electronic inductive effects of the substituents provided lesser impact on donor strength modification of imidazole base and that alkylation of 1-imidazole position did not yield the anticipated push of electron density in favour of the N-donor atom. It is anticipated that the results should promote the understanding of azole-containing bio-macromolecular species

  14. Hydraulic properties of naturally regenerated beech saplings respond to canopy opening.

    PubMed

    Caquet, Blandine; Barigah, Têtè S; Cochard, Hervé; Montpied, Pierre; Collet, Catherine; Dreyer, Erwin; Epron, Daniel

    2009-11-01

    Enhanced sapling growth in advance regeneration requires gaps in the canopy, but is often delayed after canopy opening, because acclimation of saplings to the new environment is gradual and may last for several years. Canopy opening is expected to result in an increased transpiration because of a larger climatic demand and a higher stomatal conductance linked to the higher rates of photosynthesis. Therefore, we focused on the changes in water relations and the hydraulic properties of beech (Fagus sylvatica L.) saplings during 2 years after canopy opening. We tested the hypothesis that an increase in leaf-specific hydraulic conductance and a decrease in vulnerability to cavitation occur to sustain an enhanced transpiration. Hydraulic conductance of defoliated shoots, vulnerability to cavitation, size and density of xylem vessels as well as stomatal conductance were recorded on saplings growing in shade (S saplings) or in gaps created by opening the canopy (shade-to-light, SL saplings). Hydraulic conductance per unit cross-sectional area (K(AS)) did not differ in the shoots of S and SL saplings. But a higher ratio stem cross-sectional area/leaf area resulted in a higher leaf-specific hydraulic conductance of the shoots (K(AL)) of SL saplings. Contrary to expectations, vulnerability to cavitation increased transitorily in stems during the first year after canopy opening and no difference was observed between the two treatments in light-saturated stomatal conductance. During the second year, vulnerability to cavitation was similar in the S and SL saplings and light-saturated stomatal conductance increased in SL saplings. These results demonstrate a release of the hydraulic constraints after canopy opening with an adjustment of the ratio stem cross-sectional area/leaf area. But the larger vulnerability to cavitation during the first year could limit stomatal opening and therefore the ability of beech saplings to use the available light for photosynthesis and could

  15. How active site protonation state influences the reactivity and ligation of the heme in chlorite dismutase

    PubMed Central

    Streit, Bennett R.; Blanc, Béatrice; Lukat-Rodgers, Gudrun S.; Rodgers, Kenton R.; DuBois, Jennifer L.

    2010-01-01

    Chlorite dismutase catalyzes O2 release from chlorite with exquisite efficiency and specificity. The spectroscopic properties, ligand binding affinities, and steady state kinetics of chlorite dismutase from Dechloromonas aromatica were examined over pH 3–11.5 to gain insight into how the protonation state of the heme environment influences dioxygen formation. An acid/base transition was observed by UV/visible and resonance Raman spectroscopy with a pKa of 8.7, 2–3 pH units below analogous transitions observed in typical His-ligated peroxidases. This transition marks the conversion of a five coordinate high spin Fe(III) to a mixed high/low spin ferric-hydroxide, as confirmed by resonance Raman (rR) spectroscopy. The two Fe–OH stretching frequencies are quite low, consistent with a weak Fe–OH bond, despite the nearly neutral imidazole side chain of the proximal histidine ligand. The hydroxide is proposed to interact strongly with a distal H-bond donor, thereby weakening the Fe–OH bond. The rR spectra of Cld-CO as a function of pH reveal two forms of the complex, one in which there is minimal interaction of distal residues with the carbonyl oxygen and another, acidic form in which the oxygen is under the influence of positive charge. Recent crystallographic data reveal arginine 183 as the lone H-bond donating residue in the distal pocket. It is likely that this Arg is the strong, positively charged H-bond donor implicated by vibrational data to interact with exogenous axial heme ligands. The same Arg in its neutral (pKa ~ 6.5) form also appears to act as the active site base in binding reactions of protonated ligands, such as HCN, to ferric Cld. The steady state profile for the rate of chlorite decomposition is characterized by these same pKas. The 5 coordinate high spin acidic Cld is more active than the alkaline hydroxide-bound form. The acid form decomposes chlorite most efficiently when the distal Arg is protonated/cationic (maximum kcat = 2.0 (±0.6)

  16. A Calorimetric Method for Determination of Heat Capacity of Ceramics for Concentrated Solar Thermal Systems / Skenējošās Kalorimetrijas Metode Siltumietilpības Noteikšanai Saules Kolektoru Keramikā

    NASA Astrophysics Data System (ADS)

    Kalnačs, J.; Grehovs, V.; Mežinskis, G.; Bidermanis, L.

    2013-10-01

    Differential scanning calorimetry was carried out to determine the heat capacity (Cp) of the high temperature resistant ceramic materials to be used as protective coatings for stainless steel tubes of parabolic trough solar collectors in concentrated solar power (CSP) systems. The Cp(T) measurements and calculations were performed at continuous scanning in the temperature range 20-800 °C. In the work, calibration curves have been derived for conversion of measuring units from mcV into mW. To achieve a better repeatability of measurements, methods for stabilization of the thermal contact between the sample-containing vessel and the probe have been developed. The Cp(T) dependence was obtained for different ceramic materials. Rakstā izklāstīta izstrādātā metodika keramikas un emalju siltumietilpības noteikšanai pēc diferenciālās skenējošās kalorimetrijas mērījumiem. Parādīta virkne traucējošo faktoru kalibrēšanas līknes un mērījumu veikšanai, piedāvātas metodes to samazināšanai vai novēršanai, precīzāku rezultātu ieguvei. Noteikta siltumietilpības atkarība no temperatūras virknei emalju, kas var tikt izmantotas saules siltuma kolektoros, kā aizsargpārklājumi. Parādīta siltumietilpības noteikšanas atkārtojamības atkarība no siltuma kontakta. Izstrādāta metode termiskā kontakta stabilizācijai. Virknei emalju noteikta siltumietilpības atkarība no temperatūras diapazonā 20 - 800°C.

  17. A Histidine Residue of the Influenza Virus Hemagglutinin Controls the pH Dependence of the Conformational Change Mediating Membrane Fusion

    PubMed Central

    Mair, Caroline M.; Meyer, Tim; Schneider, Katjana; Huang, Qiang; Veit, Michael

    2014-01-01

    ABSTRACT The conformational change of the influenza virus hemagglutinin (HA) protein mediating the fusion between the virus envelope and the endosomal membrane was hypothesized to be induced by protonation of specific histidine residues since their pKas match the pHs of late endosomes (pKa of ∼6.0). However, such critical key histidine residues remain to be identified. We investigated the highly conserved His184 at the HA1-HA1 interface and His110 at the HA1-HA2 interface of highly pathogenic H5N1 HA as potential pH sensors. By replacing both histidines with different amino acids and analyzing the effect of these mutations on conformational change and fusion, we found that His184, but not His110, plays an essential role in the pH dependence of the conformational change of HA. Computational modeling of the protonated His184 revealed that His184 is central in a conserved interaction network possibly regulating the pH dependence of conformational change via its pKa. As the propensity of histidine to get protonated largely depends on its local environment, mutation of residues in the vicinity of histidine may affect its pKa. The HA of highly pathogenic H5N1 viruses carries a Glu-to-Arg mutation at position 216 close to His184. By mutation of residue 216 in the highly pathogenic as well as the low pathogenic H5 HA, we observed a significant influence on the pH dependence of conformational change and fusion. These results are in support of a pKa-modulating effect of neighboring residues. IMPORTANCE The main pathogenic determinant of influenza viruses, the hemagglutinin (HA) protein, triggers a key step of the infection process: the fusion of the virus envelope with the endosomal membrane releasing the viral genome. Whereas essential aspects of the fusion-inducing mechanism of HA at low pH are well understood, the molecular trigger of the pH-dependent conformational change inducing fusion has been unclear. We provide evidence that His184 regulates the pH dependence of

  18. Designing green oxidation catalysts for purifying environmental waters

    PubMed Central

    Ellis, W. Chadwick; Tran, Camly T.; Roy, Riddhi; Rusten, Marte; Fischer, Andreas; Ryabov, Alexander D.

    2010-01-01

    We describe the synthesis, characterization, aqueous behavior, and catalytic activity of a new generation of FeIII-TAML (TetraAmido Macrocycle Ligand) activators of peroxides (2), variants of (2d), which have been designed to be especially suitable for purifying water of recalcitrant oxidizable pollutants. Activation of H2O2 by 2 (kI) as a function of pH was analyzed via kinetic studies of Orange II bleaching. This was compared with the known behavior of the first generation of FeIII-TAMLs (1). Novel reactivity features impact the potential for oxidant activation for water purification by 2d and its aromatic ring substituted dinitro (2e) and tetrachloro (2f) derivatives. Thus, the maximum activity for 2e occurs at pH 9, the closest yet to the EPA guidelines for drinking water (6.5–8.5) allowing 2e to rapidly activate H2O2 at pH 7.7. In water, 2e has two axial water ligands with pKas of 8.4 and 10.0 (25 °C). The former is the lowest for all FeIII-TAMLs developed to date and is key to 2e’s exceptional catalytic activity in neutral and slightly basic solutions. Below pH 7 2d was found to be quite sensitive to demetalation in phosphate buffers. This was overcome by iterative design to give 2e (hydrolysis rate 2d > 100×2e). Mechanistic studies highlight 2e’s increased stability by establishing that to demetalate 2e at a comparable rate to which H2PO4− demetalates 2d, H3PO4 is required. A critical criterion for green catalysts for water purification is the avoidance of endocrine disruptors, which can impair aquatic life. FeIII-TAMLs do not alter transcription mediated by mammalian thyroid, androgen or estrogen hormone receptors, suggesting that 2 do not bind to the receptors and reducing concerns that the catalysts might have endocrine disrupting activity. PMID:20565079

  19. Kinetic Mechanism of Human Histidine Triad Nucleotide Binding Protein 1 (Hint1)

    PubMed Central

    Zhou, Xin; Chou, Tsui-Fen; Aubol, Brandon E; Park, Chin Ju; Wolfenden, Richard; Adams, Joseph; Wagner, Carston R.

    2013-01-01

    Human histidine triad nucleotide binding protein 1 (hHint1) is a member of a ubiquitous and ancient branch of the histidine triad (HIT) protein superfamily. hHint1 is a homodimeric protein that catalyzes the hydrolysis of model substrates, phosphoramidate (TpAd) and acyl adenylate (AIPA), with a high efficiency. Recently, catalytically inactive hHint1 has been identified as the cause of inherited peripheral neuropathy (1). We have carried out the first detailed kinetic mechanistic studies of hHint1 and have found that the reaction mechanism is consistent with a double displacement mechanism, in which the active site nucleophile His112 is first adenylylated by the substrate, followed by hydrolysis of the AMP-enzyme intermediate. A transient burst phase followed by a linear phase from the stopped-flow fluorescence assay indicated that enzyme adenylylation was faster than the subsequent intermediate hydrolysis and product release. Solvent viscosity experiments suggested that both chemical transformation and diffusion-sensitive events (product release or protein conformational change) limit the overall turnover. The catalytic trapping experiments and data simulation indicated that the true koff rate of the final product AMP is unlikely to control the overall kcat. Therefore, a protein conformational change associated with product release is likely rate limiting. In addition, the rate of Hint1 adenylylation was found to be dependent on two residues with pKas of 6.5 and 8, with the former pKa agreeing well with the NMR titration results for the pKa of the active site nucleophile His112. When compared to the uncatalyzed rates, hHint1 was shown to enhance acyl-AMP and AMP phosphoramidate hydrolysis by 106 to 108- fold. Taken together, our analysis indicates that hHint1 catalyzes the hydrolysis of phosphoramidate and acyl adenylate with high efficiency, through a mechanism that relies on rapid adenylylation of the active residue, His-112, while being partially rate limited

  20. The effects of drug complexation on the stability and conformation of human serum albumin: protein unfolding.

    PubMed

    Ahmed-Ouameur, A; Diamantoglou, S; Sedaghat-Herati, M R; Nafisi, Sh; Carpentier, R; Tajmir-Riahi, H A

    2006-01-01

    We report different analytical methods used to study the effects of 3\\'-azido-3\\'-deoxythymidine, aspirin, taxol, cisplatin, atrazine, 2,4-dichlorophenoxyacetic, biogenic polyamines, chlorophyll, chlorophyllin, poly(ethylene glycol), vanadyl cation, vanadate anion, cobalt-hexamine cation, and As2O3, on the stability and secondary structure of human serum albumin (HSA) in aqueous solution, using capillary electrophoresis, Fourier transform infrared, ultraviolet visible, and circular dichroism (CD) spectroscopic methods. The concentrations of HSA used were 4% to 2% or 0.6 to 0.3 mM, while different ligand concentrations were 1 microM to 1 mM. Structural data showed drugs are mostly located along the polypeptide chains with both specific and nonspecific interactions. The stability of drug-protein complexes were in the order K(VO(2+)) 1.2 x 10(8) M(-1) > K(AZT) 1.9 x 10(6) M(-)1 > K(PEG) 4.1 x 10(5) M(-1) > K(atrazine) 3.5 x 10(4) M(-1) > K(chlorophyll) 2.9 x 10(4) M(-1) > K2,4-D 2.5 x 10(4) M-1 > K(spermine) 1.7 x 10(4) M(-1) > K(taxol) 1.43 x 10(4) M(-1) > K(Co(3+)) > 1.1 x 10(4) M(-1) > K(aspirin) 1.04 x 10(4)i(-1) > K(chlorophyllin) 7.0 x 10(3) M(-1) > K(VO(3)(-)) 6.0 x 103 M(-1) > K(spermidine) 5.4 x 10(3) M(-1) > K(putrescine) 3.9 x 10(3) M(-1) > K(As(2)O(3)) 2.2 x 10(3) M(-1)> K(cisplatin) 1.2 x 10(2) M(-1). The protein conformation was altered (infrared and CD results) with major reduction of alpha-helix from 60 to 55% (free HSA) to 49 to 40% and increase of beta-structure from 22 to 15% (free HSA) to 33 to 23% in the drug-protein complexes. The alterations of protein secondary structure are attributed to a partial unfolding of HSA on drug complexation.

  1. The Miocene to Recent evolution of an active transform fault at the junction of Hellenic and Cyprus Arcs, eastern Mediterranean: the linkage between the western Antalya Basin and Finike Basin and Anaximander Seamounts

    NASA Astrophysics Data System (ADS)

    Cinar, E.; King, H.; Aksu, A.; Hall, J.; Gurcay, S.; Çifçi, G.

    2011-12-01

    A 100 km-wide transform ('STEP') fault zone separates the Hellenic and Cyprus Arcs at the convergent plate boundary of the eastern Mediterranean, where the African plate to the south is being subducted below the Aegean-Anatolian microplate to the north. The eastern edge of the transform fault zone is a N-S transtensional lineament which occurs at the shelf edge between the onland Bey Daglari mountains and the offshore Antalya Basin. The lineament runs northwards to the Isparta Angle in southern Turkey; and continues southwards to veer to the southwest through the Anaximander Seamounts to connect with the Strabo Trough. The Finike Basin lies immediately west of the transtensional fault zone, and south of the Turkish shelf. Its Pliocene-Quaternary sedimentary fill is trapped between the shelf and the Anaximander Seamounts, which appear to override it in a shallow-dipping north-verging thrust which carries the Sirri Erinç Plateau. Recent acquisition of around 1500 km of multi-channel seismic reflection profiles has enabled us to discern the relationships of the Finike Basin with the fault systems which bound it. Miocene thrusts verging to the south characterise the area, and many are reactivated in Pliocene-Quaternary time, accompanied by back thrusts (verging to the north) indicative of transpression. A north-verging thrust carries the Sirri Erinç Plateau over the southern margin of the Finike Basin, and similarly-verging thrusts occur within the Basin. These, like the back-thrusts, are indicative of the (?)sinistral transpression that characterizes the STEP fault zone in Pliocene-Quaternary time. The Kas 1 well illustrates south-verging thrusting on land, probably as a continuation of the contraction in the Taurides to the north. We suggest that the normal faulting along the coast is superficial and gravitational, formed on the back of the deep thrusts carrying Tauride Mountains. The Finike Basin has similarities with the adjacent Rhodes Basin. It is a deep

  2. Experimental and Numerical Study of Swirling Flows and Flame Dynamics

    NASA Astrophysics Data System (ADS)

    Abricka, M.; Barmina, I.; Valdmanis, R.; Zake, M.

    2014-08-01

    The effect of swirling air on the flow dynamics was investigated for the cold non-reacting flows and the flame arising at thermo-chemical conversion of biomass pellets downstream of a cylindrical channel. Under experimental and numerical investigation was the swirling flow dynamics with the primary axial air supply below a biomass layer and swirling air supply above it. The results indicate that for cold flows the swirling air jet outflow from tangential nozzles leads to the formation of a complex flow dynamics which is influenced both by upstream and downstream air swirl propagation near the channel walls, with correlating swirl-enhanced formation of the upstream and downstream axial flows close to the flow centreline depending on the swirling air supply rate. These axial flows can be completely balanced at their stagnation within the axial recirculation zone. It is shown that at equal boundary conditions for the swirling flame and the cold flows the swirling flow dynamics is influenced by the upstream air swirl-enhanced mixing of the reactants below the air swirl nozzles. This determines the formation of a downstream reaction zone with correlating development of the flow velocity, temperature and composition profiles in the downstream flame regions with improved combustion stability. The low swirl intensity in these regions prevents the formation of a recirculation zone Ir veikti kompleksi aukstu nereaģējošu un liesmas virpuļplūsmu dinamikas veidošanās eksperimentālie pētījumi, izvērtējot galvenos faktorus, kas ietekmē šo plūsmu dinamikas veidošanos cilindriskā kanālā virs granulēta biomasas slāņa pie aksiālas primārā gaisa padeves zem granulu slāņa un gaisa virpuļplūsmas padeves virs tā. Auksto virpuļplūsmu pētījumi apliecina, ka plūsmas dinamiku būtiski ietekmē divu savstarpēji konkurējošu un pretēji vērstu virpuļplūsmu veidošanās pie tangenciālās gaisa padeves sprauslas izejas. Lejupvērstā virpuļplūsma, kas

  3. The partitioning behavior of As and Au in S-free and S-bearing magmatic assemblages

    NASA Astrophysics Data System (ADS)

    Simon, Adam C.; Pettke, Thomas; Candela, Philip A.; Piccoli, Philip M.; Heinrich, Christoph A.

    2007-04-01

    The partitioning of As and Au between rhyolite melt and low-salinity vapor (2 wt% NaCl eq.) in a melt-vapor-Au metal ± magnetite ± pyrrhotite assemblage has been quantified at 800 °C, 120 MPa and f=NNO. The S-bearing runs have calculated values for the fugacities of H 2S, SO 2 and S 2 of logfS=1.1, logf=-1.5, and logf=-3.0. The ratio of H 2S to SO 2 is on the order of 400. The experiments constrain the effect of S on the partitioning behavior of As and Au at magmatic conditions. Calculated average Nernst-type partition coefficients (±1 σ) for As between vapor and melt, DAsv/m, are 1.0 ± 0.1 and 2.5 ± 0.3 in the S-free and S-bearing assemblages, respectively. These results suggest that sulfur has a small, but statistically meaningful, effect on the mass transfer of As between silicate melt and low-salinity vapor at the experimental conditions. Efficiencies of removal, calculated following Candela and Holland (1986), suggest that the S-free and S-bearing low-salinity vapor can scavenge approximately 41% and 63% As from water-saturated rhyolite melt, respectively, during devolatilization assuming that As is partitioned into magnetite and pyrrhotite during second boiling. The S-free data are consistent with the presence of arsenous acid, As(OH) 3 in the vapor phase. However, the S-bearing data suggest the presence of both arsenous acid and a As-S complex in S-bearing magmatic vapor. Apparent equilibrium constants, logKAs'(±1σ), describing the partitioning of As between melt and vapor are -1.3 (0.1) and -1.1 (0.1) for the S-free and S-bearing runs, respectively. The increase in the value of KAs' with the addition of S suggests a role for S in complexing and scavenging As from the melt during degassing. The calculated vapor/melt partition coefficients (±1 σ) for Au between vapor and melt, DAuv/m, in S-free and S-bearing assemblages are 15 ± 2.5 and 12 ± 0.3, respectively. Efficiencies of removal ( Candela and Holland, 1986) for the S-free melt, calculated

  4. 15N nuclear magnetic resonance studies of acid-base properties of pyridoxal-5'-phosphate aldimines in aqueous solution.

    PubMed

    Sharif, Shasad; Huot, Monique Chan; Tolstoy, Peter M; Toney, Michael D; Jonsson, K Hanna M; Limbach, Hans-Heinrich

    2007-04-19

    By use of 15N NMR spectroscopy, we have measured the pKa values of the aldimines 15N-(pyridoxyl-5'-phosphate-idine)-methylamine (2a), N-(pyridoxyl-5'-phosphate-15N-idine)-methylamine (2b), and 15N-(pyridoxyl-idine)-methylamine (3). These aldimines model the cofactor pyridoxal-5'-phosphate (PLP, 1) in a variety of PLP-dependent enzymes. The acid-base properties of the aldimines differ substantially from those of the free cofactor in the aldehyde form 1a or in the hydrated form 1b, which were also investigated using 15N NMR for comparison. All compounds contain three protonation sites, the pyridine ring, the phenol group, and the side chain phosphate (1, 2) or hydroxyl group (3). In agreement with the literature, 1a exhibits one of several pKas at 2.9 and 1b at 4.2. The 15N chemical shifts indicate that the corresponding deprotonation occurs partially in the pyridine and partially in the phenolic site, which compete for the remaining proton. The equilibrium constant of this ring-phenolate tautomerism was measured to be 0.40 for 1a and 0.06 for 1b. The tautomerism is essentially unaltered above pH 6.1, where the phosphate group is deprotonated to the dianion. This means that the pyridine ring is more basic than the phenolate group. Pyridine nitrogen deprotonation occurs at 8.2 for 1a and at 8.7 for 1b. By contrast, above pH 4 the phosphate site of 2 is deprotonated, while the pyridine ring pKa is 5.8. The Schiff base nitrogen does not deprotonate below pH 11.4. When the phosphate group is removed, the pKa of the Schiff base nitrogen decreases to 10.5. The phenol site cannot compete for the proton of the Schiff base nitrogen and is present in the entire pH range as a phenolate, preferentially hydrogen bonded to the solvent. The intrinsic 15N chemical shifts provide information about the hydrogen bond structures of the protonated and unprotonated species involved. Evidence is presented that the intramolecular OHN hydrogen bond of PLP aldimines is broken in aqueous

  5. Gravimetric and Spectroscopic Studies of Reversible Hydrogen Sorption on Nanoporous Clinoptilolite

    NASA Astrophysics Data System (ADS)

    Lesnicenoks, P.; Grinberga, L.; Kleperis, J.

    2014-06-01

    Large surface aluminosilicate compounds such as zeolites are not the best option for hydrogen storage due to their low hydrogen sorption capacity above cryogenic temperatures. However, the known crystal structure and easy ion exchange allows considering zeolites as easily tuneable media that with a little effort can be changed to suitable porous media for hydrogen sorption. Metal (Li, Mg) and ammonia ion exchange is performed in natural clinoptilolite samples with the aim to increase the amount of adsorbed hydrogen. The Fourier transform infrared spectroscopy of the prepared samples is used to study sorption of hydrogen molecules in the vicinity of light metal ions. An original thermogravimetric method is applied to characterise the amount of sorbed hydrogen. Our experiments show that the highest hydrogen uptake (~ 6.2 wt%) is for a clinoptilolite sample treated in acid. The cation exchange did not provide the expected hydrogen sorption capability; however, the amount of sorbed hydrogen exceeded that for the initial material. Lielas virsmas alumosilikāta savienojumi, piemēram, ceolīti, nav labākais risinājums ūdeņraža uzglabāšanai, ņemot vērā to niecīgo sorbētā ūdeņraža daudzumu temperatūrā, kas augstāka par kriogēno. Tomēr zināmā kristāla struktūra un vieglā jonu apmaiņas iespēja paver iespēju izmantot ceolītus kā viegli pielāgojamu materiālu, kuru ar nelielām modifikācijām var pārveidot par piemērotu vidi ūdeņraža sorbcijai. Darbā metālu (Li, Mg) un amonjaka jonu apmaiņa tiek veikta dabīgā klinoptilolīta paraugos ar mērķi palielināt sorbētā ūdeņraža daudzumu materiālā. Furjē infrasarkanā spektroskopija tiek izmantota, lai pētītu ūdeņraža molekulas sorbciju vieglo metālu jonu tuvumā. Oriģināla termogravimetrijas metode tiek pielietota, lai raksturotu uzkrātā ūdeņraža daudzumu paraugos. Eksperimentālie rezultāti liecina, ka vislielākais uzkrātā ūdeņraža daudzums (~6,2 masas%) ir ar

  6. Electrostatic modification of the active site of myoglobin: characterization of the proximal Ser92Asp variant.

    PubMed

    Lloyd, E; Burk, D L; Ferrer, J C; Maurus, R; Doran, J; Carey, P R; Brayer, G D; Mauk, A G

    1996-09-10

    derivative. The metMbCN and deoxyMb derivatives also exhibit pH-dependent behavior, with pKas of 5.60 +/- 0.07 and 6.60 +/- 0.07, respectively, compared to the wild-type values of 5.4 +/- 0.04 and 5.8 +/- 0.1. The heme-linked ionizable group is proposed to be His97 in all three derivatives. The reduction potential of the variant is 72 +/- 2 mV vs SHE [25.0 degrees C, mu = 0.10 M (phosphate), pH 6.0], an increase of 8 mV over the wild-type value. The possible influence of a number of variables on the magnitude of the reduction potential in myoglobin and other heme proteins is discussed.

  7. In pursuit of empowerment: Sensei Nellie Kleinsmidt, race and gender challenges in South Africa.

    PubMed

    Jones, D E

    2001-01-01

    This chapter traces the way in which Nellie Kleinsmidt, known as the grandmother of karate in Africa, has negotiated discriminatory practices and overcome race and gender-related struggles, including the struggle to free the female body, in pursuit of empowerment. It explores her expectations and the constraints and frustrations she experienced, as well as the many contributions she has made to women's karate in South Africa. Nellie Kleinsmidt's karate career, which began in 1965, coincided with the early developments of South African karate. As a woman of colour her life and karate career were significantly shaped by apartheid legislation. It divided the country into areas of occupancy and residency according to race and was designed to prevent contact between the people of the government defined race groups. Black karate-kas were prohibited by law from practising karate in white designated areas. Lack of facilities and qualified instructors in areas allocated to Kleinsmidt's race group meant that she received very little formal karate instruction between 1966 and 1973. Soon after, she met Johan Roux, a white male. He was to become her chief karate instructor and life-long companion. They defied the apartheid legislation and in 1978 set up home together. They organized defiance campaigns, resisting the pressures from government to close their dojo because of its non-racial policies. Freeing her body at the broader political level involved the abolition of the race categories and all other apartheid legislation which impacted on her life choices and experiences. Initially this struggle and that of freeing her body occurred simultaneously. In her ongoing struggle against gender discrimination in the sport, it was in karate that Nellie Kleinsmidt could strive for the personal empowerment she sought. She could however not translate this into freedom in South African society itself. The impact of apartheid legislation together with the imposition of a sports moratorium

  8. Influence of Light Intensity and Temperature on Cultivation of Microalgae Desmodesmus Communis in Flasks and Laboratory-Scale Stirred Tank Photobioreactor

    NASA Astrophysics Data System (ADS)

    Vanags, J.; Kunga, L.; Dubencovs, K.; Galvanauskas, V.; Grīgs, O.

    2015-04-01

    Optimization of the microalgae cultivation process and of the bioprocess in general traditionally starts with cultivation experiments in flasks. Then the scale-up follows, when the process from flasks is transferred into a laboratory-scale bioreactor, in which further experiments are performed before developing the process in a pilot-scale reactor. This research was done in order to scale-up the process from a 0.4 1 shake flask to a 4.0 1 laboratory-scale stirred-tank photobioreactor for the cultivation of Desmodesmus (D.) communis microalgae. First, the effect of variation in temperature (21-29 ºC) and in light intensity (200-600 μmol m-2s-1) was studied in the shake-flask experiments. It was shown that the best results (the maximum biomass concentration of 2.72 g 1-1 with a specific growth rate of 0.65 g g-1d-1) can be achieved at the cultivation temperature and light intensity being 25 °C and 300 μmol m2s-1, respectively. At the same time, D. communis cultivation under the same conditions in stirred-tank photobioreactor resulted in average volumetric productivities of biomass due to the light limitation even when the light intensity was increased during the experiment (the maximum biomass productivity 0.25 g 1-1d-1; the maximum biomass concentration 1.78 g 1-1). Mikroaļģu kultivēšanas procesa optimizēšana parasti sākas ar kultivēšanas eksperimentiem kolbās. Tālāk seko procesa pārnese uz laboratorijas mēroga fotobioreaktoru, kurā tiek veikti tālāki eksperimenti, pirms tiek izveidots pilota mēroga reaktors. Šis pētījums tika veikts ar mērķi, pārnest Desmodesmus communis kultivēšanas procesu no 0.4 1 kolbas uz 4.0 1 laboratorijas fotobioreaktoru. Vispirms tika pētīta dažādu temperatūru (21-29 ºC) un gaismas intensitātes (200-600 μmol m-2s-1) ietekme uz aļģu biomasu veicot eksperimentus kolbās. Labākie rezultāti (maksimālā biomasas koncentrācija 2.72 g 1-1; īpatnējais augšanas ātrums 0.65 g g-1d-1) sasniegti, kad

  9. Biochemical characterization of the arginine-specific proteases of Porphyromonas gingivalis W50 suggests a common precursor.

    PubMed Central

    Rangarajan, M; Smith, S J; U, S; Curtis, M A

    1997-01-01

    Extracellular proteases of Porphyromonas gingivalis specific for arginyl peptide bonds are considered to be important virulence factors in periodontal disease. In order to determine the number, inter-relationship and kinetic properties of these proteases, extracellular enzymes with this peptide-bond specificity were purified and characterized from P. gingivalis W50. Three forms, which we denote RI, RI-A and RI-B, accounted for all of the activity in the supernatant. All three enzymes contain an alpha chain of approximately 54 kDa with the same N-terminal amino acid sequence. RI is a heterodimer of non-covalently linked alpha and beta chains which migrate to the same position on SDS/PAGE but which can be resolved by 8 M urea/PAGE. RI-A and RI-B are both monomeric, but the molecular mass of RI-B (70-80 kDa) is significantly increased due to post-translational modification with lipopolysaccharide. All forms show absolute specificity for peptide bonds with Arg in the P1 position and are also capable of hydrolysing N-terminal Arg and C-terminal Arg-Arg peptide bonds. Thus they show limited amino- and carboxy-peptidase activity. For the hydrolysis of Nalpha-benzoyl-L-Arg-p-nitroanilide, the pH optimum is 8.0 at 30 degrees C. The Vmax for all three enzymes is controlled by ionization of two residues with apparent pKas at 30 degrees C of 6. 5+/-0.05 and 9.7+/-0.05, and DeltaH values of approximately 29 kJ/mol and approximately 24 kJ/mol in the enzyme-substrate complex. By analogy with papain, the pKa of 6.5 could be ascribed to a Cys and the pKa of 9.7 to a His residue. E-64 [L-trans-epoxysuccinyl-leucylamide-4-(4-guanidino)butane] is a competitive inhibitor of RI, RI-A and RI-B. Based on physical properties and kinetic behaviour, RI-A appears to be analogous to gingipain from P. gingivalis HG66. However the alpha/beta structure of RI differs significantly from that of the high-molecular-mass multimeric complex of gingipain containing four haemagglutinins described by

  10. Developed Design for Humeral Head Replacement Using 3D Surface Mapping

    NASA Astrophysics Data System (ADS)

    Salah, H. R.

    2014-12-01

    Assessment of dimensional and geometrical data on the humeral head replacement (HHR) objects is essential for solving the relevant designing problems in the physics of reverse engineering (RE). In this work, 2D-assessment for human humerus was performed using the computed tomography (CT) technique within the RE plan, after which the 2D images of humeral objects were converted into 3D images. The conversion was successful and indicated a clear difference in the 2D and 3D estimates of sizes and geometry of the humerus. The authors have analyzed and confirmed experimentally the statistical information on the relevant anatomical objects. The results of finite-element simulation of the compressive stresses affecting the geometry of 3D surface mapping were analyzed using SolidWorks software. For developing the biomechanical design of an HHR object suitable biomaterials were selected, and different metal-based biomaterials are discussed as applied at various loads. New methodology is presented for the size estimation of humeral head - both anatomical and artificial - in 3D-shape. A detailed interpretation is given for the results of CT D-measurements. Izmēru un ģeometrisko datu novērtējums, kas attiecas uz pleca kaula galviņas nomaiņas (PKGN) objektiem, nepieciešams, lai risinātu virkni reversīvās inženierijas (RI) problēmu. Šajā darbā cilvēka pleca kaula galviņas divdimensiju novērtējums tika veikts ar datortomogrāfijas palīdzību (RI) ietvaros, un pēc tam objekta divdimensiju attēlojums tika pārveidots trīsdimensiju. Pārveidojums bija sekmīgs, parādot pleca kaula galviņas izmēru un ģeometrijas atšķirības starp 2D un 3D novērtējumiem. Autori izanalizēja un eksperimentāli apstiprināja statistisko informāciju pēc dotā veida anatomiskiem objektiem. Saspiešanas sasprindzinājumi, kuri ietekmē trīsdimensiju virsmas attēlojuma ģeometriju, tika analizēti ar gala-elementu simulācijas metodi, lietojot programmu Solid

  11. Investigation of epstein-barr virus and parvovirus b19 DNA in allogeneic stem cell transplant patients.

    PubMed

    Atalay, Altay; Gökahmetoğlu, Selma; Durmaz, Süleyman; Kandemir, Idris; Sağlam, Derya; Kaynar, Leylagül; Eser, Bülent; Cetin, Mustafa; Kılıç, Hüseyin

    2014-06-01

    Amaç: Bu çalışmada, 2009-2010 yılları arasında allojenik kök hücre transplantasyonu (AKHT) yapılan hastalarda transplantasyon sonrası EBV ve parvovirus B19 DNA araştırılması amaçlandı. Gereç ve Yöntemler: Bu çalışmaya Erciyes Üniversitesi Tıp Fakültesi İç Hastalıkları Anabilim Dalı Hematoloji-Onkoloji Bilim Dalı’nda Nisan 2009-Kasım 2010 tarihleri arasında AKHT yapılmış 45 erişkin hasta dahil edildi. Hastaların transplantasyon sonrası 1-6. aylar arasında alınan toplam 135 plazma örneğinde EBV ve parvovirus B19 DNA varlığı gerçek zamanlı PCR yöntemi ile araştırıldı. Hastalara ait transplantasyon öncesi EBV ve parvovirus B19 serolojik göstergeleri hasta dosyalarından temin edildi. Bulgular: AKHT öncesi serolojik göstergelerde, 45 hastanın 32’sinde (%71,1) EBNA-1 IgG (+), VCA IgM (-) ve VCA IgG (+) idi. İki hastada (%4,45) EBNA-1 IgG (+), VCA IgM (-) ve VCA IgG (-), bir hastada (%2,2) EBNA-1 IgG (-), VCA IgM (-) ve VCA IgG (+) ve 2 (%4,45) hastada tüm serolojik göstergeler negatifti. Transplantasyon sonrası düşük EBV DNA pozitifliği (<600 kopya/mL) 4 (%8,9) hastada saptandı, bu hastaların hepsinde VCA IgM negatif, VCA IgG pozitif bulundu. Düşük viral yüke rağmen bu hastalarda EBV ilişkili semptom görülmemiş ve PTLD gelişmemiştir. Kırk beş hastanın 44’ünde (%97,7) parvovirus B19 IgM negatif, IgG pozitif iken sadece bir hastada (%2,3) parvovirus B19 IgM pozitif, IgG negatifti. Kırk beş hastadan elde edilen örneklerin hiçbirinde parvovirus B19 DNA saptanmadı. Sonuç: Bu çalışmada AKHT hastalarında EBV ve parvovirus B19 DNA araştırıldı. Hastaların hiçbirinde PTLD gelişmezken parvovirus B19 DNA pozitifliği de saptanmadı. Ancak bu konunun aydınlatılmasında daha geniş hasta serileri ile yapılan, prospektif, çok merkezli ileri çalışmalara ihtiyaç vardır.

  12. Venous Thromboembolism after Allogeneic Pediatric Hematopoietic Stem Cell Transplantation: A Single-Center Study.

    PubMed

    Azık, Fatih; Gökçebay, Dilek Gürlek; Tavil, Betül; Işık, Pamir; Tunç, Bahattin; Uçkan, Duygu

    2015-09-01

    Amaç: Hematopoetik kök hücre nakli (HSCT) yapılan hastalarda venöz tromboembolizm (VTE) yüksek morbiditeye sahiptir. Bu çalışmanın amacı pediatrik allojenik HSCT alıcılarındaki VTE insidansını belirlemek ve pretransplant protrombotik risk faktörlerinin trombozdaki rolünü saptamaktır. Yöntem ve Gereçler: Nisan 2010-Kasım 2012 tarihleri arasında allojenik HSCT yapılan ve HSCT sonrası 100 gününü tamamlayan 92 hasta retrospektif olarak değerlendirildi. Kök hücre nakli öncesinde tüm hastalardan koagülasyon profili, kazanılmış ve konjenital protrombotik risk faktörlerinden faktör V Leiden, protrombin G20210A, metilentetrahidrofolat redüktaz (MTHFR) C677T, MTHFR A1298C mutasyonları ile serum homosistein ve lipoprotein(a), plazma antitrombin III, protein C ve protein S düzeyleri alındı. Bulgular: Trombofili taramasında; toplam sekiz hasta (%9) faktör V Leiden heterozigot, beş hasta (%6) MTHFR 677TT homozigot, 12 hasta (%14) MTHFR 1298CC homozigot ve iki (%2) hasta prothrombin G20210A heterozigot mutasyonuna sahipti. Venöz tromboembolizm beş hastada (%5.4) izlendi; herhangi bir protrombotik risk faktörü beş hastadan üçünde tespit edilirken, dört hastanın santral venöz kateteri vardı. Venöz tromboembolizm ile kalıtsal protrombotik risk faktörleri arasında anlamlı ilişki saptanmadı. Sonuç: Hematopoetik kök hücre nakli sonrasında VTE; muhtemelen düşük dozda düşük moleküler ağırlıklı heparin kullanımına bağlı olarak az sıklıkta görülebilen bir komplikasyon olup, prospektif bir çalışma yapılmaksızın kalıtsal protrombotik risk faktörlerinin trombozdaki rolünün tam olarak dışlanması mümkün değildir.

  13. Projects of High-Temperature Nuclear Reactors

    NASA Astrophysics Data System (ADS)

    Ekmanis, J.; Tomsons, E.; Zeltiņš, N.

    2013-04-01

    Part 2 of the overview gives emphasis to the projects of high-temperature NRs, whose development is an area of active engagement for the specialists from the USA, France, Japan, Russia, China, the Netherlands, and Germany. Projects of several powerful NRs of the HTGR type for commercial use had been worked out in the USA and Germany already by 1970 but not yet implemented. Augstas temperatūras ar gāzes dzesēšanu HTGR (High Temperature Gas cooled Reactor) tipa kodolreaktoru (KR) izstrādes koncepcija bija piedāvāta 1956. gadā Lielbritānijā. Apmēram tanī pašā laikā minētā tipa KR izstrādi uzsāka Vācijā un ASV. HTGR tipa KR kodoldegviela un kodoldegvielas atražošanas materiāla sīkās daļiņas ar diametru apmēram 0.5 mm pārklātas ar vairākām aizsargkārtām un atrodas grafīta neitronu palēninātājā, kas aizsargā daļiņas no neitronu palēninātāja un dzesētāja iedarbes. Augstas temperatūras KR bez hēlija gāzes siltumnesēja var izmantot šķidrus metālus (nātriju, svinu vai svina-bismuta sakausējumu) un izkausētu sāli. Pašlaik darbojās divi augstas temperatūras ar hēlija gāzi dzesēti eksperimentālie HTGR tipa KR. Viens Japānā "HTTR" no 1998. gada oktobra (sākts būvēt 1991. gada 15. martā) ar 30 MWth siltuma jaudu. Otrs Ķīnā "HTR-10" no 2000.gada decembra (sākts būvēt 1995. gada14. jūnijā) ar 10 MWth siltuma jaudu. Ķīnā Shandong provincē 2011.gada aprīlī uzsāka augstas temperatūras "HTR-PM" (High Temperature Gas-cooled Reactor - Pebble bed Module) tipa kodolreaktora celtniecību ar 250 MWth siltuma jaudu. Augstas temperatūras kodolreaktoru izstrādē pašlaik aktīvi iesaistīti ASV, Francijas, Japānas, Krievijas, Ķīnas, Nīderlandes un Vācijas speciālisti.

  14. Identity of Innovative Multifunctional Material Manufacturing Business in Latvia / Inovatīvu Daudzfunkcionālo Materiālu Ražotāju Identitāte Latvijā

    NASA Astrophysics Data System (ADS)

    Geipele, I.; Staube, T.; Ciemleja, G.; Zeltins, N.; Ekmanis, Yu.

    2015-08-01

    The publication comprises the results from the practical scientific investigation to define the profile and distinctions of the Latvian innovative multifunctional material manufacturing industry. The research is carried out by a holistic approach, including expert interviews, qualitative analysis of the official register data, practical survey, and financial data analysis. The paper seeks to give the detailed data on a technological profile of the mentioned representative companies, if there is a synergy or tough competition in the Latvian market. The current research is topical, because it is unique and does not have analogues in Latvia, and the research is timely due to correspondence with recently stated Research and Innovation Strategies for Smart Specialisation in Latvia. The main findings are associated with recognition of the factors that make impact on commercialisation of the finished goods, obtained financial results and planned directions of development of the respondent companies. Publikācija sniedz veiktā zinātniski praktiskā pētījuma rezultātus, kura ietvaros tika noteikts Latvijas inovatīvu daudzfunkcionālo materiālu ražotāju darbības profils un identitāte. Pētījumā tika izmantota kompleksās analīzes metode, kas ietvēra ekspertu intervijas, uzņēmumu oficiāli reģistrēto datu kvalitatīvo analīzi, zinātniski praktisko aptauju, kā arī pētāmo uzņēmumu finanšu darbības rezultātu analīzi. Zinātniskais darbs sniedz izsmeļošu informāciju par mērķa uzņēmumu tehnoloģisko profilu un pēta, vai Latvijas mērķa ražošanas nozarē ir sinerģijas vai sīvās konkurences pazīmes. Šim zinātniskajam pētījumam ir noteikta aktualitāte saskaņā ar tā unikalitāti Latvijas valsts mērogā un atbilstība Viedās specializācijas stratēģijai. Pētījuma galvenie secinājumi ir saistīti ar uzņēmumu produkcijas komercializācijas ietekmējošo faktoru apzināšanu, sasniegtajiem finansiālajiem rezultātiem un pl

  15. Kinetics of the hydrolysis of N-benzoyl-l-serine methyl ester catalysed by bromelain and by papain. Analysis of modifier mechanisms by lattice nomography, computational methods of parameter evaluation for substrate-activated catalyses and consequences of postulated non-productive binding in bromelain- and papain-catalysed hydrolyses

    PubMed Central

    Wharton, Christopher W.; Cornish-Bowden, Athel; Brocklehurst, Keith; Crook, Eric M.

    1974-01-01

    of α-N-benzoyl-l-arginine amide; Km1 and k for the serine ester hydrolysis are somewhat similar to Km and kcat. for the arginine amide hydrolysis and Kas and k′ for the serine ester hydrolysis are somewhat similar to Km and kcat. for the arginine ester hydrolysis. 9. A previous interpretation of the inter-relationships of the values of kcat. and Km for the bromelain-catalysed hydrolysis of the arginine ester and amide substrates is discussed critically and an alternative interpretation involving substantial non-productive binding of the arginine amide substrate to bromelain is suggested. 10. The parameters for the bromelain-catalysed hydrolysis of the serine ester substrate are tentatively interpreted in terms of non-productive binding in the binary complex and a decrease of this type of binding by ternary complex-formation. 11. The Michaelis parameters for the papain-catalysed hydrolysis of the serine ester substrate (Km=52±4mm, kcat.=2.80±0.1s−1 at pH7.0, I=0.1, 25.0°C) are similar to those for the papain-catalysed hydrolysis of methyl hippurate. 12. Urea and guanidine hydrochloride at concentrations of 1m have only small effects on the kinetic parameters for the hydrolysis of the serine ester substrate catalysed by bromelain and by papain. PMID:4455211

  16. UV Sensing Properties of ZnO Nanowires Grown on Glass by Rapid Thermal Oxidation of Zinc Films

    NASA Astrophysics Data System (ADS)

    Mihailova, I.; Gerbreders, V.; Sļedevskis, Ē.; Bulanovs, A.; Paškevičs, V.

    2014-08-01

    The nanostructured ZnO thin films were successfully synthesized by rapid thermal oxidation of metallic zinc films without catalysts or additives. On the surface of thin films the formation of ZnO nanowires was observed. In the work, the optical and electrical parameters and photoresponses of the obtained ZnO thin films were investigated. Nanostructured thin films of the type have a promising potential for the use in optoelectronics, sensor technique and biomedical sciences Šī darba galvenais mērķis bija izpētīt UV fotodetektora izgatavošanas iespējamību uz nanostrukturētu ZnO plāno kārtiņu bāzes, kas sintezētas termiski oksidējot Zn plānās kārtiņas. Termiskās oksidēšanas rezultātā tika novērota adatveidīgu ZnO nanostruktūru formēšanās uz kārtiņu virsmas. Izpētītas iegūto paraugu optiskās un elektriskās īpašības, kā arī fotoreakcija. Tika konstatēts, ka iegūto nanostrukturēto ZnO kārtiņu elektriskā vadītspēja ir ārkārtīgi jutīga pret UV starojumu, taču, apstarojot ar redzamo gaismu, strāva paliek gandrīz nemainīga. Kārtiņu elektriskās vadītspējas fotoreakcija ir atkarīga arī no nanostruktūru daudzuma uz virsmas. Visaugstākā UV fotovadītspēja tika novērota paraugam ar vislielāko ZnO nanoadatu koncentrāciju. UV gaismas inducētais vadītspējas pieaugums ļauj ZnO nanoadatas reversīvi pārslēgt starp stāvokļiem "ieslēgts" un "izslēgts". Līdz ar to, šīs fotojutīgās nanoadatas var tikt izmantotas UV gaismas detektoros un optiskajos slēdžos. Šādas nanostrukturētas plānās kārtiņas var tikt pielietotas arī ķīmiskajos un bioloģiskajos sensoros, pjezoelektriskajās ierīcēs, saules elementos utt. Turklāt, šādu nanostrukturēto ZnO plāno kārtiņu sintēzes process ir salīdzinoši lēts un vienkāršs, dodot iespēju liela mēroga produkcijas ražošanai

  17. Effects of Using Channelling Devices to Increase Efficiency of Hydrokinetic Devices

    NASA Astrophysics Data System (ADS)

    Kalnacs, A.; Kalnacs, J.; Mutule, A.; Entins, V.

    2015-04-01

    In the rivers of Latvia and of many other countries the flow velocity in the places that are most suitable for installation of hydrokinetic devices is 0.4 to 0.9 m/s. In a stream or a river the hydrokinetic devices can reach full efficiency starting from about twice higher flow velocities. It is advisable to at least double this velocity thus increasing the efficiency and power output of the hydrokinetic devices installed in such places. Since Latvia has abundance of slow rivers and almost none are fast, research in this field is of high importance. Diversified technical methods are known that allow increasing substantially the efficiency of hydrokinetic devices. These methods include the use of diffusers, concentrators, different types of other channelling devices and means of flow control. Desirable effects are achieved through changing the cross-section and/or direction of a flow, its pressure, minimizing the turbulence, etc. This work substantiates the use of such devices for increasing the efficiency of hydrokinetic devices. A method is proposed for evaluation of the effects on power output gained owing to the use of channelling devices. Results show that the efficiency of hydrokinetic devices can be increased by at least 110%. Kā rāda pētījumi, Latvijā upju vietās, kuras ir piemērotas hidrokinētisko HES ierīkošanai, straumes ātrums pārsvarā ir robežās 0,4 līdz 0,9 m/s. Būtu izdevīgi vismaz dubultot šo ātrumu, līdz ar to būtiski palielinot šādās vietās izvietojamo iekārtu efektivitāti un jaudu. Sakarā ar to, ka Latvijā ir daudz tieši lēni plūstošu upju, minēto tēmu izpēte un iekārtu izmantošana Latvijai ir sevišķi aktuāla. Ir zināmi dažādi tehniskie paņēmieni, kas dod iespējas būtiski palielināt hidrokinētisko iekārtu efektivitāti. Šādas iespējas dod koncentratori, difuzori, dažādi plūsmas virzītāji un citi speciāli plūsmas vadības paņēmieni. Šīs ierīces maina straumes šķērsgriezumu un

  18. Micro-grid for on-site wind-and-hydrogen powered generation

    NASA Astrophysics Data System (ADS)

    Suskis, P.; Andreiciks, A.; Steiks, I.; Krievs, O.; Kleperis, J.

    2014-02-01

    The authors propose a micro-grid for autonomous wind-and-hydrogen power generation thus replacing such traditional fossil-fuelled equipment as domestic diesel generators, gas micro-turbines, etc. In the proposed microgrid the excess of electrical energy from a wind turbine is spent on electrolytic production of hydrogen which is then stored under low-pressure in absorbing composite material. The electrolyser has a non-traditional feeding unit and electrode coatings. The proposed DC/DC conversion topologies for different micro-grid nodes are shown to be well-designed. The prototypes elaborated for the converters and hydrogen storage media were tested and have demonstrated a good performance. Rakstā piedāvātā mikrotīkla izpēte ir veikta ar mērķi izstrādāt autonomu, uz vēja un ūdeņraža enerģiju balstītu elektroapgādes sistēmu, kas varētu aizvietot tradicionālās fosilā kurināmā sistēmas, piemēram, mājsaimniecību dīzeļa ģeneratorus, gāzes mikroturbīnas u.c. Mikrotīkla elektroapgādes sistēmā vēja agregāta saražotā elektroenerģija tiek pārveidota atbilstoši standarta maiņsprieguma elektroapgādes parametriem un piegādāta slodzei. Pārpalikusī enerģija tiek pārveidota un uzkrāta ūdeņraža formā, izmantojot elektrolīzes iekārtu un kompozītmateriālu uzkrājēju. Ja pieejamā vēja enerģija nenosedz slodzes enerģijas patēriņu, elektroenerģijas padeves funkciju ar atbilstoša energoelektronikas pārveidotāja palīdzību pārņem ūdeņraža degvielas elements. Ja, savukārt, slodzei nav nepieciešama enerģija, no vēja saražoto enerģiju izmanto elektrolīzes iekārta un tā tiek uzkrāta ūdeņraža formā, atbilstoši uzkrājēja ietilpībai. Piedāvātajā mikrotīklā ir izmantota elektrolīzes iekārta ar netradicionāliem elektrodu pārklājumiem un barošanas bloku, kā arī zemspiediena kompozītmateriālu ūdeņraža uzkrājējs. Galvenie mikrotīkla elektriskās enerģijas pārveidošanas mezgli ir

  19. An ecodesign method for reducing the effects of hazardous substances in the product lifecycle

    NASA Astrophysics Data System (ADS)

    Simanovska, J.; Valters, K.; Bažbauers, G.; Luttropp, C.

    2012-10-01

    ārtējo vidi novēršanu. Tāpēc radīta jauna, daļēji kvantitatīva ekodizaina metode, apvienojot produktu izstrādes prasības ar zinātniskā ķīmiskā riska novērtēšanas principiem, kas piedāvā bīstamo īpašību prioritizēšanu, izmantojot Globāli harmonizētās sistēmas ķīmisko vielu klasifikācijas kodus, kā arī iedarbības un materiālu efektivitātes aspektu prioritizēšanu. Metode tika aprobēta, demonstrējot tās izmantošanu. Metode ļauj produkta izstrādātājam identificēt pārmaiņu nepieciešamību, izstrādāt ekodizaina priekšlikumus, izvērtēt alternatīvas, un palīdz uzlabot saziņu par materiālu īpašībām un ietekmi uz vidi un cilvēka veselību izejvielu un produktu piegādes ķēdē.

  20. Wear Calculation for Sliding Friction Pairs

    NASA Astrophysics Data System (ADS)

    Springis, G.; Rudzitis, J.; Avisane, A.; Leitans, A.

    2014-04-01

    One of the principal objectives of modern production process is the improvement of quality level; this means also guaranteeing the required service life of different products and increase in their wear resistance. To perform this task, prediction of service life of fitted components is of crucial value, since with the development of production technologies and measuring devices it is possible to determine with ever increasing precision the data to be used also in analytical calculations. Having studied the prediction theories of wear process that have been developed in the course of time and can be classified into definite groups one can state that each of them has shortcomings that might strongly impair the results thus making unnecessary theoretical calculations. The proposed model for wear calculation is based on the application of theories from several branches of science to the description of 3D surface micro-topography, assessing the material's physical and mechanical characteristics, substantiating the regularities in creation of the material particles separated during the wear process and taking into consideration definite service conditions of fittings. ums Mūsdienu ražošanas procesa viens no pamatmērķiem ir produkcijas kvalitātes līmeņa paaugstināšana, tas nozīmē arī dažādu izstrādājumu nepieciešamā kalpošanas laika nodrošināšanu un nodilumizturības palielināšanu. Svarīga loma šī uzdevuma sasniegšanā ir salāgojamo detaļu kalpošanas laika prognozēšanai, kas ir ļoti aktuāls jautājums, jo attīstoties dažādām ražošanas, kā arī mēriekārtu tehnoloģijām, kļūst iespējams arvien precīzāk noteikt nepieciešamos datus, kuri vēlāk tiek izmantoti arī analītiskajos aprēķinos. Apskatot laika gaitā izstrādātās dilšanas procesa prognozēšanas teorijas, kuras var klasificēt, apkopojot tās noteiktās grupās, ņemot par pamatu līdzīgas teorētiskās pieejas, jāsaka, ka katrai no tām piemīt da

  1. Power Generation Investment Planning in a Modern Power System With High Share of Renewables

    NASA Astrophysics Data System (ADS)

    Oleinikova, I.; Ruksans, O.; Turcik, M.

    2014-04-01

    This article is focused on investment planning in power generation industry, which becomes an important direction of research under the conditions of newly formed environment of electricity market. The authors emphasize the key role of effective instruments and methods for estimation of the costs and economic efficiency of a generating capacity and its adequacy in a modern power system. In the paper, cost-based concepts are analyzed which form a basis for decision-making and long-term planning of investments in the power generation sector for a power system with high share of renewable energy sources. Mūsdienās energoinfrastruktūras attīstības un tā vadības procesā ir jāpieņem un jāpilda vairāki lēmumi par nepieciešamiem kapitālieguldījumiem, kas ir rūpīgi jāplāno un jāpamato. Viedo tīklu tehnoloģiju ieviešana un energosistēmas drošuma uzturēšana, ņemot vērā liberalizēto elektroenerģijas tirgu, rada nepieciešamību pēc principiāli jaunām pieejām un metodēm kapitālieguldījumu novērtēšanas uzdevumu risināšanai. Pētījums veltīts investīciju plānošanai elektroenerģijas ģenerācijas iekārtai elektroenerģijas tirgus apstākļos, ņemot vērā lielo atjaunīgo energoresursu (AER) īpatsvaru. Modernu energosistēmu vadība prasa pietiekamu ģenerācijas jaudas elastīgumu un to pareizo kombināciju. Lai to sasniegtu, vispirms ir nepieciešama dažādu ģenerācijas tehnoloģijas izmaksu novērtēšana, ko var veikt, izmantojot pienācīgo instrumentu. Tas arī ir pētījuma mērķis, kura rezultātā tika piedāvāta elektrostaciju ekonomiskas dzīvotspējas novērtēšanas koncepcija, balstoties uz elektroenerģijas ražošanas līmeņizmaksām (ed costs), lai salīdzinātu dažādu elektroenerģijas ražošanas tehnoloģijas izmaksas. Lai to sasniegtu tika veikti: - investīciju plānošana ģenerācijā, metožu pētīšana; - elektrostaciju darbības principu analīze elektroenerģijas tirgū; - elektrostaciju

  2. Determination of Two-Liquid Mixture Composition by Assessing Dielectric Parameters 1. Precise Measuring System / Divu Šķidrumu Maisījuma Sastāva Noteikšana, Izvērtējot to Dielektriskos Parametrus 1. Precīza Mērīšanas Sistēma

    NASA Astrophysics Data System (ADS)

    Vilitis, O.; Shipkovs, P.; Merkulovs, D.

    2013-08-01

    ,01%. Šajā darbā piedāvātajā jaunajā mērīšanas sistēmas struktūras risinājumā iekļautas divas tiešas signālu digitālās sintēzes mikrosistēmas, kas ar augstu precizitāti ģenerē mērīšanai nepieciešamās formas, fāzes un amplitūdas signālus ar 100,000 kHz frekvenci un tiek vadītas no mikrokontrolera. Mērīšanas sistēmā izmantota mērsignālu sinhronizētās detektēšanas tehnika. Izstrādātās sistēmas konigurācija, mērīšanas režīma uzstādījums un vadība automātiski praktiski izslēdz virkni mērīšanas signālu parazītisko fāzes nobīžu un fāzes uzstādījumu kļūdas. Izstrādātā mērīšanas sistēma ērti piemērojama vispārējai izmantošanai kapacitātes vai impedances mērierīcēs. Samērā nelielā prognozējamā mērīšanas sistēmas pašizmaksa un kompaktā, portatīvā konstrukcija, kā arī iepriekš minētās priekšrocības paplašina sistēmas lietojumu ne tikai etanola koncentrācijas mērīanai bioetanola ražošanas procesā, bet šī sistēma var tikt izmantota arī eļļas, benzīna un citu degvielu testēšanai, ķīmiskajā, farmācijas un pārtikas industrijā, mikrobioloģijā un medicīnā, lai noteiktu glikozes, antigēnu, antivielu, proteīna, DNS fragmentu un citu vielu saturu šķīdumos u.c.

  3. Reduction of Electric Breakdown Voltage in LC Switching Shutters / Elektriskās Caursites Sprieguma Samazināšana Šķidro Kristālu Šūnās

    NASA Astrophysics Data System (ADS)

    Mozolevskis, G.; Ozols, A.; Nitiss, E.; Linina, E.; Tokmakov, A.; Rutkis, M.

    2015-10-01

    ātes dēļ ir liela varbūtība šķidro kristālu (LC) šūnā novērot elektrisko caursiti, kuras laikā LC šūna tiek sabojāta. Šis ir viens no galvenajiem iemesliem, kāpēc šāda tipa ekrāni pagaidām vēl nav komerciāli plaši pieejami. Šajā darbā mēs skaidrojam rezultātus, kas iegūti, veicot LC šūnu caursites pētījumus. Elektrisko caursiti LC šūnā novēro brīdī, kad strāva tajā pārsniedz noteiktu sliekšņa vērtību. Strāvas stipruma sliekšņa vērtību nosaka šķidrā kristāla īpatnējā vadītspējā, kā arī punktu defekti LC šūnā, piemēram, putekļi, elektrodu raupjums, caurumi u.c. Strāvas stipruma ierobežošanai šūnā šajā darbā tika izmantotas dažādas metodes - buferslāņu iekļaušana, elektroda izlīdzinošā slāņa iekļaušana, kā arī elektroda sadalīšana ar lāzera ablācijas metodi. Tiek demonstrēts, ka elektrisko lauku, pie kura novēro caursiti šūnās, ir iespējams būtiski palielināt, šūnā iekļaujot elektriskos izolējošus buferslāņus un sadalot elektrodu.

  4. PREFACE: Liquid-solid interfaces: structure and dynamics from spectroscopy and simulations Liquid-solid interfaces: structure and dynamics from spectroscopy and simulations

    NASA Astrophysics Data System (ADS)

    Gaigeot, Marie-Pierre; Sulpizi, Marialore

    2012-03-01

    energy electron diffraction (LEED), He atom scattering (HAS) and STM, to investigate the organization of water on metal, namely Pd(111) and Pt(111). Direct measurements of hyperpolarizabilities for non-linear spectroscopy can be made through hyper-Rayleigh scattering experiments, which are presented here by the group of P F Brevet on gold and silver nanoparticles. From the point of view of molecular dynamics simulations of interfaces, complementary levels of calculations are presented in this special section. The groups of K Leung, M-P Gaigeot, M Sulpizi and M Sprik provide theoretical investigations with DFT-based molecular dynamics simulations. Leung et al and Gaigeot et al address the hot topic issue of the reactivity of oxides surface sites and especially reliable methods to calculate pKas of these sites, with simulations taking into account both the solid and the liquid explicitly, and at the same first principles level of theory. Gaigeot, Sprik and Sulpizi furthermore combine the information on the structural organization of liquid water at the interface with quartz and alumina via pKa calculations and vibrational features (and their microscopic assignments). Mixed quantum/classical molecular dynamics (QM/MM) simulations are presented by Ishiyama and Morita for the investigation of another topical interface, i.e. the liquid-air interface. They provide the theoretical VSFG spectrum of the water-vapor interface and some understanding at the microscopic level of the experimental vibrational features. Molecular dynamics simulations based on empirical force fields have been applied to investigate hydrophobic interfaces by the groups of B Space and P Carloni. Carloni et al address salt effects at water-hydrophobic interfaces, investigating how the salts affect the structural organization of water at these interfaces. Space et al provide theoretical approximations to VSFG calculations in the special case of the carbon tetrachloride-water interface and the assignments of