Direct determination of tungsten in the presence of high content of molybdenum in the form of its complex with bromopyrogallol red and hydrogen peroxide

International Nuclear Information System (INIS)

Andreeva, I.Yu.; Lebedeva, L.I.; Flotskaya, E.A.

1982-01-01

It has been shown that tungsten reacts with Bromopyrogallol Red and hydrogen peroxide to form a ternary complex. A procedure has been developed of determining tungsten(6) in the presence of 500 times molar amounts of molybdenum(6). Under the conditions chosen molybdenum forms a stable peroxide complex and does not interfere with the determination

New bisaminoethanethiol (BAT) ligands which form two interconvertible Tc-99m complexes

Energy Technology Data Exchange (ETDEWEB)

Oya, Shunichi; Kung, Mei-Ping; Frederick, Dana; Kung, Hank F

1995-08-01

Most commonly used radiopharmaceuticals in diagnostic nuclear medicine are labeled with Tc-99m. This is due to its superior physical characteristics (T{sub (1(2))} = 6 h and gamma energy 140 KeV) and convenient availability from the {sup 99}Mo/{sup 99mm}Tc generator. In an attempt to fine tune the properties of Tc-99m complexes, the synthesis and radiolabeling of two novel N{sub 2}S{sub 2} ligands, N,-2-mercaptobenzyl-N'-(1-oxo-2-mercapto-2-methyl)propyl ethylenediamine,8, and N,-2-methylthiobenzyl-N'-(1-oxo-2-mercapto-2-methyl)propyl ethylenediamine, 11, with an ionizable SH or unionizable SMe group, respectively, for the formation of complexes with Tc{sup v}O center cores, have been examined. Both ligands initially formed one apparently stable, lipophilic and neutral complex (HPLC, Rt = 7 min, reverse-phase column, acetonitrile: buffer, pH 7.0; (55(45)); V/V; partition coefficient between 1-octanol and buffer of 410 and 335, respectively) with [{sup 99m}Tc]pertechnetate in the presence of stannous chloride. After treatment with a reducing agent, NaCNBH{sub 3}, the initial [{sup 99m}Tc]8 and 11 complexes were reduced; the reduced complexes were less lipophilic (shorter retention time, Rt = 5 min, on the same reversed phase HPLC). However, only the oxidized form showed sufficient stability. The reduced forms of both [{sup 99m}Tc]8 and 11 were readily and completely converted back to the oxidized forms by a stream of air. Biodistribution studies in rats demonstrated that the [{sup 99m}Tc]8 (oxidized form) penetrated the blood-brain barrier (0.67% dose/organ at 2 min postinjection), but washed out from the brain quickly (0.29% dose/organ at 30 min postinjection). On the contrary, [{sup 99m}Tc]11 (oxidized form) did not show any brain uptake (0.03% dose/organ at 2 min postinjection), despite its higher lipophilicity. The disparity between these two Tc-99m complexes may be related to the relative instability of [{sup 99m}Tc]11 (oxidized form) by the introduction of the

Phase behaviour and structure of stable complexes of oppositely charged polyelectrolytes

Science.gov (United States)

Mengarelli, V.; Auvray, L.; Zeghal, M.

2009-03-01

We study the formation and structure of stable electrostatic complexes between oppositely charged polyelectrolytes, a long polymethacrylic acid and a shorter polyethylenimine, at low pH, where the polyacid is weakly charged. We explore the phase diagram as a function of the charge and concentration ratio of the constituents. In agreement with theory, turbidity and ζ potential measurements show two distinct regimes of weak and strong complexation, which appear successively as the pH is increased and are separated by a well-defined limit. Weak complexes observed by neutron scattering and contrast matching have an open, non-compact structure, while strong complexes are condensed.

Formulation of stable protein powders by supercritical fluid drying

NARCIS (Netherlands)

Jovanović, N.

2007-01-01

Protein pharmaceuticals are potent drugs for the treatment of several chronic and life-threatening diseases. However, the complex and sensitive nature of protein molecules requires special attention in the development of stable dosage forms. Developing stable aqueous protein formulations is often a

Modelling of the flow of stable air over a complex region

CSIR Research Space (South Africa)

Scholtz, MT

1976-01-01

Full Text Available The flow of stable air over a general region of complex topography and non-uniform surface temperature has been investigated. In order to gain further understanding of the motion of surface air, it was necessary to study the vertical structure...

Preparation and thermal properties of form stable paraffin phase change material encapsulation

International Nuclear Information System (INIS)

Liu Xing; Liu Hongyan; Wang Shujun; Zhang Lu; Cheng Hua

2006-01-01

Paraffin waxes are cheap and have moderate thermal energy storage density but low thermal conductivity and, hence, require large surface area to be used in energy storage. Form stable paraffin phase change materials (PCM) in which paraffin serves as a latent heat storage material and polyolefins act as a supporting material, because of paraffin leakage, are required to be improved. The form stable paraffin PCM in the present paper was encapsulated in an inorganic silica gel polymer successfully by in situ polymerization. The differential scanning calorimeter (DSC) was used to measure its thermal properties. At the same time, the Washburn equation, which measures the wetting properties of powder materials, was used to test the hydrophilic-lipophilic properties of the PCMs. The result indicated that the enthalpy of the microencapsulated PCMs was reduced little, while their hydrophilic properties were enhanced largely

The retro-GCN4 leucine zipper sequence forms a stable three-dimensional structure

Science.gov (United States)

Mittl, Peer R. E.; Deillon, Christine; Sargent, David; Liu, Niankun; Klauser, Stephan; Thomas, Richard M.; Gutte, Bernd; Grütter, Markus G.

2000-01-01

The question of whether a protein whose natural sequence is inverted adopts a stable fold is still under debate. We have determined the 2.1-Å crystal structure of the retro-GCN4 leucine zipper. In contrast to the two-stranded helical coiled-coil GCN4 leucine zipper, the retro-leucine zipper formed a very stable, parallel four-helix bundle, which now lends itself to further structural and functional studies. PMID:10716989

Measuring the Complexity of Urban Form and Design

OpenAIRE

Boeing, Geoff

2017-01-01

Complex systems have become a popular lens for conceptualizing cities, and complexity has substantial implications for urban performance and resilience. This paper develops a typology of methods and measures for assessing the complexity of the built form at the scale of urban design. It extends quantitative methods from urban planning, network science, ecosystems studies, fractal geometry, and information theory to the physical urban form and the analysis of qualitative human experience. Metr...

Preparation and properties of lauric acid/silicon dioxide composites as form-stable phase change materials for thermal energy storage

International Nuclear Information System (INIS)

Fang Guiyin; Li Hui; Liu Xu

2010-01-01

Form-stable lauric acid (LA)/silicon dioxide (SiO 2 ) composite phase change materials were prepared using sol-gel methods. The LA was used as the phase change material for thermal energy storage, with the SiO 2 acting as the supporting material. The structural analysis of these form-stable LA/SiO 2 composite phase change materials was carried out using Fourier transformation infrared spectroscope (FT-IR). The microstructure of the form-stable composite phase change materials was observed by a scanning electronic microscope (SEM). The thermal properties and thermal stability were investigated by a differential scanning calorimeter (DSC) and a thermogravimetric analysis apparatus (TGA), respectively. The SEM results showed that the LA was well dispersed in the porous network of SiO 2 . The DSC results indicated that the melting latent heat of the form-stable composite phase change material is 117.21 kJ kg -1 when the mass percentage of the LA in the SiO 2 is 64.8%. The results of the TGA showed that these materials have good thermal stability. The form-stable composite phase change materials can be used for thermal energy storage in waste heat recovery and solar heating systems.

Polymorphic drugs examined with neutron spectroscopy: Is making more stable forms really that simple?

International Nuclear Information System (INIS)

Tsapatsaris, Nikolaos; Landsgesell, Sven; Koza, Michael M.; Frick, Bernhard; Boldyreva, Elena V.; Bordallo, Heloisa N.

2013-01-01

Highlights: • Pressure induced transition in the denser polymorphic form. • Weak strength of hydrogen bonds driving new stable packing. • Lattice anisotropy versus charge transfer. - Abstract: Understanding polymorphism in pharmaceutical ingredients is a long-standing challenge in formulation science. A well-known example is paracetamol, C 8 H 9 NO 2 . The marketed stable form I crystallizes with corrugated molecular layers. In contrast, form II, which is thermodynamically favorable at high pressures, has relatively planar layers that can slip over each other without difficulty, but is metastable at ambient conditions. By means of inelastic neutron scattering we demonstrated that the lattice modes of form II exhibit a sudden 1 meV energy shift at 300 K under a pressure of ca 0.4 GPa. Moreover, evidence of an increase of the vibrational energy in both polymorphs was found, which was accompanied, in form I, by an unexpectedly weak increase of the tunnel splitting. These results indicate an anisotropy of the potential surface probed by the methyl rotor, and are discussed in relation to the differences of the strength of the hydrogen bond environment for each polymorph

Polymorphic drugs examined with neutron spectroscopy: Is making more stable forms really that simple?

Energy Technology Data Exchange (ETDEWEB)

Tsapatsaris, Nikolaos [European Spallation Source ESS AB, P.O. Box 176, SE-221 00 Lund (Sweden); Landsgesell, Sven [Helmholtz Zentrum Berlin, Hahn-Meitner Platz, 1, 14109 Berlin (Germany); Koza, Michael M.; Frick, Bernhard [Institut Laue-Langevin, BP 156 38042, Grenoble Cedex 9 (France); Boldyreva, Elena V. [Novosibirsk State University, ul. Pirogova 2, Novosibirsk 630090 (Russian Federation); Institute of Solid State Chemistry and Mechanochemistry, ul. Kutateladze 18, Novosibirsk 630128 (Russian Federation); Bordallo, Heloisa N., E-mail: bordallo@nbi.ku.dk [Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen (Denmark)

2013-12-12

Highlights: • Pressure induced transition in the denser polymorphic form. • Weak strength of hydrogen bonds driving new stable packing. • Lattice anisotropy versus charge transfer. - Abstract: Understanding polymorphism in pharmaceutical ingredients is a long-standing challenge in formulation science. A well-known example is paracetamol, C{sub 8}H{sub 9}NO{sub 2}. The marketed stable form I crystallizes with corrugated molecular layers. In contrast, form II, which is thermodynamically favorable at high pressures, has relatively planar layers that can slip over each other without difficulty, but is metastable at ambient conditions. By means of inelastic neutron scattering we demonstrated that the lattice modes of form II exhibit a sudden 1 meV energy shift at 300 K under a pressure of ca 0.4 GPa. Moreover, evidence of an increase of the vibrational energy in both polymorphs was found, which was accompanied, in form I, by an unexpectedly weak increase of the tunnel splitting. These results indicate an anisotropy of the potential surface probed by the methyl rotor, and are discussed in relation to the differences of the strength of the hydrogen bond environment for each polymorph.

Preparation and flammability of high density polyethylene/paraffin/organophilic montmorillonite hybrids as a form stable phase change material

International Nuclear Information System (INIS)

Cai, Yibing; Hu, Yuan; Song, Lei; Kong, Qinghong; Yang, Rui; Zhang, Yinping; Chen, Zuyao; Fan, Weicheng

2007-01-01

A kind of form stable phase change material (PCM) based on high density polyethylene (HDPE), paraffin, organophilic montmorillonite (OMT) and intumescent flame retardant (IFR) hybrids is prepared by using a twin screw extruder technique. This kind of form stable PCM is made of paraffin as a dispersed phase change material and HDPE as a supporting material. The structure of the montmorillonite (MMT) and OMT is characterized by X-ray diffraction (XRD) and high resolution electron microscopy (HREM). The analysis indicates that the MMT is a kind of lamellar structure, and the structure does not change after organic modification. However, the structure of the hybrid is evidenced by the XRD and scanning electronic microscope (SEM). Its thermal stability, latent heat and flame retardant properties are given by the Thermogravimetry analysis (TGA), differential scanning calorimeter (DSC) method and cone calorimeter, respectively. Synergy is observed between the OMT and IFR. The XRD result indicates that the paraffin intercalates into the silicate layers of the OMT, thus forming a typically intercalated hybrid. The SEM investigation and DSC result show that the additives of OMT and IFR have hardly any effect on the HDPE/paraffin three dimensional netted structure and the latent heat. In TGA curves, although the onset of weight loss of flame-retardant form stable PCMs occur at a lower temperature than that of form stable PCM, flame-retardant form stable PCMs produce a large amount of char residue at 700 o C. The synergy between OMT and IFR leads to the decrease of the heat release rate (HRR), contributing to improvement of the flammability performance

Exact simulation of max-stable processes.

Science.gov (United States)

Dombry, Clément; Engelke, Sebastian; Oesting, Marco

2016-06-01

Max-stable processes play an important role as models for spatial extreme events. Their complex structure as the pointwise maximum over an infinite number of random functions makes their simulation difficult. Algorithms based on finite approximations are often inexact and computationally inefficient. We present a new algorithm for exact simulation of a max-stable process at a finite number of locations. It relies on the idea of simulating only the extremal functions, that is, those functions in the construction of a max-stable process that effectively contribute to the pointwise maximum. We further generalize the algorithm by Dieker & Mikosch (2015) for Brown-Resnick processes and use it for exact simulation via the spectral measure. We study the complexity of both algorithms, prove that our new approach via extremal functions is always more efficient, and provide closed-form expressions for their implementation that cover most popular models for max-stable processes and multivariate extreme value distributions. For simulation on dense grids, an adaptive design of the extremal function algorithm is proposed.

Serum albumin forms a lactoferrin-like soluble iron-binding complex in presence of hydrogen carbonate ions.

Science.gov (United States)

Ueno, Hiroshi M; Urazono, Hiroshi; Kobayashi, Toshiya

2014-02-15

The iron-lactoferrin complex is a common food ingredient because of its iron-solubilizing capability in the presence of hydrogen carbonate ions. However, it is unclear whether the formation of a stable iron-binding complex is limited to lactoferrin. In this study, we investigated the effects of bovine serum albumin (BSA) on iron solubility and iron-catalyzed lipid oxidation in the presence of hydrogen carbonate ions. BSA could solubilize >100-fold molar equivalents of iron at neutral pH, exceeding the specific metal-binding property of BSA. This iron-solubilizing capability of BSA was impaired by thermally denaturing BSA at ≥ 70 °C for 10 min at pH 8.5. The resulting iron-BSA complex inhibited iron-catalyzed oxidation of soybean oil in a water-in-oil emulsion measured using the Rancimat test. Our study is the first to show that BSA, like lactoferrin, forms a soluble iron-binding complex in the presence of hydrogen carbonate ions. Copyright © 2013 Elsevier Ltd. All rights reserved.

Dynamical complexity changes during two forms of meditation

Science.gov (United States)

Li, Jin; Hu, Jing; Zhang, Yinhong; Zhang, Xiaofeng

2011-06-01

Detection of dynamical complexity changes in natural and man-made systems has deep scientific and practical meaning. We use the base-scale entropy method to analyze dynamical complexity changes for heart rate variability (HRV) series during specific traditional forms of Chinese Chi and Kundalini Yoga meditation techniques in healthy young adults. The results show that dynamical complexity decreases in meditation states for two forms of meditation. Meanwhile, we detected changes in probability distribution of m-words during meditation and explained this changes using probability distribution of sine function. The base-scale entropy method may be used on a wider range of physiologic signals.

Preparation, characterization and thermal properties of styrene maleic anhydride copolymer (SMA)/fatty acid composites as form stable phase change materials

International Nuclear Information System (INIS)

Sari, Ahmet; Alkan, Cemil; Karaipekli, Ali; Onal, Adem

2008-01-01

Fatty acids such as stearic acid (SA), palmitic acid (PA), myristic acid (MA) and lauric acid (LA) are promising phase change materials (PCMs) for latent heat thermal energy storage (LHTES) applications, but high cost is the major drawback of them, limiting their utility area in thermal energy storage. The use of fatty acids as form stable PCMs will increase their feasibilities in practical applications due to the reduced cost of the LHTES system. In this regard, a series of styrene maleic anhydride copolymer (SMA)/fatty acid composites, SMA/SA, SMA/PA, SMA/MA, and SMA/LA, were prepared as form stable PCMs by encapsulation of fatty acids into the SMA, which acts as a supporting material. The encapsulation ratio of fatty acids was as much as 85 wt.% and no leakage of fatty acid was observed even when the temperature of the form stable PCM was over the melting point of the fatty acid in the composite. The prepared form stable composite PCMs were characterized using optic microscopy (OM), viscosimetry and Fourier transform infrared (FT-IR) spectroscopy methods, and the results showed that the SMA was physically and chemically compatible with the fatty acids. In addition, the thermal characteristics such as melting and freezing temperatures and latent heats of the form stable composite PCMs were measured by using the differential scanning calorimetry (DSC) technique, which indicated they had good thermal properties. On the basis of all the results, it was concluded that form stable SMA/fatty acid composite PCMs had important potential for practical LHTES applications such as under floor space heating of buildings and passive solar space heating of buildings by using wallboard, plasterboard or floors impregnated with a form stable PCM due to their satisfying thermal properties, easy preparation in desired dimensions, direct usability without needing additional encapsulation thereby eliminating the thermal resistance caused by the shell and, thus, reducing the cost of

Asymptotically stable fourth-order accurate schemes for the diffusion equation on complex shapes

International Nuclear Information System (INIS)

Abarbanel, S.; Ditkowski, A.

1997-01-01

An algorithm which solves the multidimensional diffusion equation on complex shapes to fourth-order accuracy and is asymptotically stable in time is presented. This bounded-error result is achieved by constructing, on a rectangular grid, a differentiation matrix whose symmetric part is negative definite. The differentiation matrix accounts for the Dirichlet boundary condition by imposing penalty-like terms. Numerical examples in 2-D show that the method is effective even where standard schemes, stable by traditional definitions, fail. The ability of the paradigm to be applied to arbitrary geometric domains is an important feature of the algorithm. 5 refs., 14 figs

PEG/SiO2–Al2O3 hybrid form-stable phase change materials with enhanced thermal conductivity

International Nuclear Information System (INIS)

Tang, Bingtao; Wu, Cheng; Qiu, Meige; Zhang, Xiwen; Zhang, Shufen

2014-01-01

The thermal conductivity of form-stable PEG/SiO 2 phase change material (PCM) was enhanced by in situ doping of Al 2 O 3 using an ultrasound-assisted sol–gel method. Fourier transform infrared spectroscopy (FT-IR) was used to characterize the structure, and the crystal performance was characterized by the X-ray diffraction (XRD). Differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA) were used to determine the thermal properties. The phase change enthalpy of PEG/SiO 2 –Al 2 O 3 reached 124 J g −1 , and thermal conductivity improved by 12.8% for 3.3 wt% Al 2 O 3 in the PCM compared with PEG/SiO 2 . The hybrid PCM has excellent thermal stability and form-stable effects. - Highlights: • The PEG/SiO 2 –Al 2 O 3 hybrid form-stable phase change material (PCM) was obtained through the sol–gel method. • The inexpensive aluminum nitrate and tetraethyl orthosilicate were used as sol precursors. • This organic–inorganic hybrid process can effectively enhance the thermal conductivity of PCMs. • The PCM exhibited high thermal stability and excellent form-stable effects

On the interconnection of stable protein complexes: inter-complex hubs and their conservation in Saccharomyces cerevisiae and Homo sapiens networks.

Science.gov (United States)

Guerra, Concettina

2015-01-01

Protein complexes are key molecular entities that perform a variety of essential cellular functions. The connectivity of proteins within a complex has been widely investigated with both experimental and computational techniques. We developed a computational approach to identify and characterise proteins that play a role in interconnecting complexes. We computed a measure of inter-complex centrality, the crossroad index, based on disjoint paths connecting proteins in distinct complexes and identified inter-complex hubs as proteins with a high value of the crossroad index. We applied the approach to a set of stable complexes in Saccharomyces cerevisiae and in Homo sapiens. Just as done for hubs, we evaluated the topological and biological properties of inter-complex hubs addressing the following questions. Do inter-complex hubs tend to be evolutionary conserved? What is the relation between crossroad index and essentiality? We found a good correlation between inter-complex hubs and both evolutionary conservation and essentiality.

Mechanisms Underlying the Formation of Complexes between Maize Starch and Lipids.

Science.gov (United States)

Chao, Chen; Yu, Jinglin; Wang, Shuo; Copeland, Les; Wang, Shujun

2018-01-10

This study aimed to reveal the mechanism of formation of complexes between native maize starch (NMS) and different types of lipids, namely palmitic acid (PA), monopalmitate glycerol (MPG), dipalmitate glycerol (DPG), and tripalmitate glycerol (TPG). The complexing index followed the order of MPG (96.3%) > PA (41.8%) > TPG (8.3%) > DPG (1.1%), indicating that MPG formed more complexes with NMS than PA, and that few complexes were formed between NMS and DPG and TPG. The NMS-PA complex presented higher thermal transition temperatures and lower enthalpy change than the NMS-MPG complex, indicating that although MPG formed more starch complexes, they had less stable crystalline structures than the complex between NMS and PA. X-ray diffraction (XRD) and Raman spectroscopy showed that both MPG and PA formed V-type crystalline structures with NMS, and confirmed that no complexes were formed between NMS and DPG and TPG. We conclude that the monoglyceride formed more starch-lipid complex with maize starch than PA, but that the monoglyceride complex had a less stable structure than that formed with PA. The di- and triglycerides did not form complexes with maize starch.

The Absence of a Mature Cell Wall Sacculus in Stable Listeria monocytogenes L-Form Cells Is Independent of Peptidoglycan Synthesis.

Science.gov (United States)

Studer, Patrick; Borisova, Marina; Schneider, Alexander; Ayala, Juan A; Mayer, Christoph; Schuppler, Markus; Loessner, Martin J; Briers, Yves

2016-01-01

L-forms are cell wall-deficient variants of otherwise walled bacteria that maintain the ability to survive and proliferate in absence of the surrounding peptidoglycan sacculus. While transient or unstable L-forms can revert to the walled state and may still rely on residual peptidoglycan synthesis for multiplication, stable L-forms cannot revert to the walled form and are believed to propagate in the complete absence of peptidoglycan. L-forms are increasingly studied as a fundamental biological model system for cell wall synthesis. Here, we show that a stable L-form of the intracellular pathogen Listeria monocytogenes features a surprisingly intact peptidoglycan synthesis pathway including glycosyl transfer, in spite of the accumulation of multiple mutations during prolonged passage in the cell wall-deficient state. Microscopic and biochemical analysis revealed the presence of peptidoglycan precursors and functional glycosyl transferases, resulting in the formation of peptidoglycan polymers but without the synthesis of a mature cell wall sacculus. In conclusion, we found that stable, non-reverting L-forms, which do not require active PG synthesis for proliferation, may still continue to produce aberrant peptidoglycan.

The Implementation of the Renormalized Complex MSSM in FeynArts and FormCalc

CERN Document Server

Fritzsche, T; Heinemeyer, S; Rzehak, H; Schappacher, C

2014-01-01

We describe the implementation of the renormalized complex MSSM (cMSSM) in the diagram generator FeynArts and the calculational tool FormCalc. This extension allows to perform UV-finite one-loop calculations of cMSSM processes almost fully automatically. The Feynman rules for the cMSSM with counterterms are available as a new model file for FeynArts. Also included are default definitions of the renormalization constants; this fixes the renormalization scheme. Beyond that all model parameters are generic, e.g. we do not impose any relations to restrict the number of input parameters. The model file has been tested extensively for several non-trivial decays and scattering reactions. Our renormalization scheme has been shown to give stable results over large parts of the cMSSM parameter space.

Extremely stable soluble high molecular mass multi-protein complex with DNase activity in human placental tissue.

Directory of Open Access Journals (Sweden)

Evgeniya E Burkova

Full Text Available Human placenta is an organ which protects, feeds, and regulates the grooving of the embryo. Therefore, identification and characterization of placental components including proteins and their multi-protein complexes is an important step to understanding the placenta function. We have obtained and analyzed for the first time an extremely stable multi-protein complex (SPC, ∼ 1000 kDa from the soluble fraction of three human placentas. By gel filtration on Sepharose-4B, the SPC was well separated from other proteins of the placenta extract. Light scattering measurements and gel filtration showed that the SPC is stable in the presence of NaCl, MgCl2, acetonitrile, guanidinium chloride, and Triton in high concentrations, but dissociates efficiently in the presence of 8 M urea, 50 mM EDTA, and 0.5 M NaCl. Such a stable complex is unlikely to be a casual associate of different proteins. According to SDS-PAGE and MALDI mass spectrometry data, this complex contains many major glycosylated proteins with low and moderate molecular masses (MMs 4-14 kDa and several moderately abundant (79.3, 68.5, 52.8, and 27.2 kDa as well as minor proteins with higher MMs. The SPC treatment with dithiothreitol led to a disappearance of some protein bands and revealed proteins with lower MMs. The SPCs from three placentas efficiently hydrolyzed plasmid supercoiled DNA with comparable rates and possess at least two DNA-binding sites with different affinities for a 12-mer oligonucleotide. Progress in study of placental protein complexes can promote understanding of their biological functions.

Complexation of carboxylate on smectite surfaces.

Science.gov (United States)

Liu, Xiandong; Lu, Xiancai; Zhang, Yingchun; Zhang, Chi; Wang, Rucheng

2017-07-19

We report a first principles molecular dynamics (FPMD) study of carboxylate complexation on clay surfaces. By taking acetate as a model carboxylate, we investigate its inner-sphere complexes adsorbed on clay edges (including (010) and (110) surfaces) and in interlayer space. Simulations show that acetate forms stable monodentate complexes on edge surfaces and a bidentate complex with Ca 2+ in the interlayer region. The free energy calculations indicate that the complexation on edge surfaces is slightly more stable than in interlayer space. By integrating pK a s and desorption free energies of Al coordinated water calculated previously (X. Liu, X. Lu, E. J. Meijer, R. Wang and H. Zhou, Geochim. Cosmochim. Acta, 2012, 81, 56-68; X. Liu, J. Cheng, M. Sprik, X. Lu and R. Wang, Geochim. Cosmochim. Acta, 2014, 140, 410-417), the pH dependence of acetate complexation has been revealed. It shows that acetate forms inner-sphere complexes on (110) in a very limited mildly acidic pH range while it can complex on (010) in the whole common pH range. The results presented in this study form a physical basis for understanding the geochemical processes involving clay-organics interactions.

Methods for forming complex oxidation reaction products including superconducting articles

International Nuclear Information System (INIS)

Rapp, R.A.; Urquhart, A.W.; Nagelberg, A.S.; Newkirk, M.S.

1992-01-01

This patent describes a method for producing a superconducting complex oxidation reaction product of two or more metals in an oxidized state. It comprises positioning at least one parent metal source comprising one of the metals adjacent to a permeable mass comprising at least one metal-containing compound capable of reaction to form the complex oxidation reaction product in step below, the metal component of the at least one metal-containing compound comprising at least a second of the two or more metals, and orienting the parent metal source and the permeable mass relative to each other so that formation of the complex oxidation reaction product will occur in a direction towards and into the permeable mass; and heating the parent metal source in the presence of an oxidant to a temperature region above its melting point to form a body of molten parent metal to permit infiltration and reaction of the molten parent metal into the permeable mass and with the oxidant and the at least one metal-containing compound to form the complex oxidation reaction product, and progressively drawing the molten parent metal source through the complex oxidation reaction product towards the oxidant and towards and into the adjacent permeable mass so that fresh complex oxidation reaction product continues to form within the permeable mass; and recovering the resulting complex oxidation reaction product

Structure of Complex Verb Forms in Meiteilon

Directory of Open Access Journals (Sweden)

Lourembam Surjit Singh

2016-12-01

Full Text Available This piece of work proposes to descriptively investigate the structures of complex verbs in Meiteilon. The categorization of such verbs is based on the nature of semantic and syntactic functions of a lexeme or verbal lexeme. A lexeme or verbal lexeme in Meiteilon may have multifunctional properties in the nature of occurrence. Such lexical items can be co-occurred together in a phrase as single functional word. Specifically, in the co-occurrences of two lexical items, the first component of lexical items has different semantic and syntactic functions in comparison to semantic and syntactic functions of the second component of lexical items. Such co-occurrences of two lexical items are the forms of complex verb that are covered with the term complex predicate in this work. The investigation in constructing complex predicate is thoroughly presenting in this work. Keywords: Structures, complex verb, conjunct verb, compound verb, complex predicate

Study on thermal property of lauric–palmitic–stearic acid/vermiculite composite as form-stable phase change material for energy storage

Directory of Open Access Journals (Sweden)

Nan Zhang

2015-09-01

Full Text Available The form-stable composite phase change material of lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite was prepared by vacuum impregnation method for thermal energy storage. The maximum mass fraction of lauric–palmitic–stearic acid ternary eutectic mixture retained in vermiculite was determined as 50 wt% without melted phase change material seepage from the composite phase change material. Fourier transformation infrared spectroscope and scanning electron microscope were used to characterize the structure and morphology of the prepared lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite form-stable composite phase change material, and the results indicate that lauric–palmitic–stearic acid ternary eutectic mixture was well confined into the layer porous structure of vermiculite by physical reaction. The melting and freezing temperatures and latent heats were measured by differential scanning calorimeter as 31.4°C and 30.3°C, and 75.8 and 73.2 J/g, respectively. Thermal cycling test showed that there was no significant change in the thermal properties of lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite form-stable composite phase change material after 1000 thermal cycles. Moreover, 2 wt% expanded graphite was added to improve the thermal conductivity of lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite form-stable composite phase change material. All results indicated that the prepared lauric–palmitic–stearic acid ternary eutectic mixture/vermiculite form-stable composite phase change material had suitable thermal properties and good thermal reliability for the application of thermal energy storage in building energy efficiency.

A water-soluble, mucoadhesive quaternary ammonium chitosan-methyl-β-cyclodextrin conjugate forming inclusion complexes with dexamethasone.

Science.gov (United States)

Piras, Anna Maria; Zambito, Ylenia; Burgalassi, Susi; Monti, Daniela; Tampucci, Silvia; Terreni, Eleonora; Fabiano, Angela; Balzano, Federica; Uccello-Barretta, Gloria; Chetoni, Patrizia

2018-03-30

The ocular bioavailability of lipophilic drugs, such as dexamethasone, depends on both drug water solubility and mucoadhesion/permeation. Cyclodextrins and chitosan are frequently employed to either improve drug solubility or prolong drug contact onto mucosae, respectively. Although the covalent conjugation of cyclodextrin and chitosan brings to mucoadhesive drug complexes, their water solubility is restricted to acidic pHs. This paper describes a straightforward grafting of methyl-β-cyclodextrin (MCD) on quaternary ammonium chitosan (QA-Ch60), mediated by hexamethylene diisocyanate. The resulting product is a water-soluble chitosan derivative, having a 10-atom long spacer between the quaternized chitosan and the cyclodextrin. The derivative is capable of complexing the model drug dexamethasone and stable complexes were also observed for the lyophilized products. Furthermore, the conjugate preserves the mucoadhesive properties typical of quaternized chitosan and its safety as solubilizing excipient for ophthalmic applications was preliminary assessed by in vitro cytotoxicity evaluations. Taken as a whole, the observed features appear promising for future processing of the developed product into 3D solid forms, such as controlled drug delivery systems, films or drug eluting medical devices.

Preparation and characterization of form-stable paraffin/polyurethane composites as phase change materials for thermal energy storage

International Nuclear Information System (INIS)

Chen, Keping; Yu, Xuejiang; Tian, Chunrong; Wang, Jianhua

2014-01-01

Highlights: • Paraffin/polyurethane composite as form-stable phase change material was prepared by bulk polymerization. • Paraffin/polyurethane composite possesses typical character of dual phase transition. • Total latent heat of n-eicosane/PUPCM is as high as 141.2 J/g. • Maximum encapsulation ratio for n-octadecane/PUPCM composites is 25% w/w. - Abstract: Polyurethane phase change material (PUPCM) has been demonstrated to be effective solid–solid phase change material for thermal energy storage. However, the high cost and complex process on preparation of PUPCMs with high enthalpy and broad phase transition temperature range can prohibit industrial-scale applications. In this work, a series of novel form-stable paraffin/PUPCMs composites (n-octadecane/PUPCM, n-eicosane/PUPCM and paraffin wax/PUPCM) with high enthalpy and broad phase transition temperature range (20–65 °C) were directly synthesized via bulk polymerization. The composites were prepared at different mass fractions of n-octadecane (10, 20, 25, 30% w/w). The results indicated that the maximum encapsulation ratio for n-octadecane/PUPCM10000 composites was around 25% w/w. The chemical structure and crystalline properties of these composites were characterized by Fourier transform infrared spectroscopy (FT-IR), polarizing optical microscopy (POM), wide-angle X-ray diffraction (WAXD). Thermal properties and thermal reliability of the composites were determined using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). From DSC analysis, the composites showed a typical dual phase change temperature. The enthalpy for the composite with 25% w/w n-eicosane was as high as 141.2 J/g. TGA analysis indicated that the composites degraded at considerably high temperatures. The process of preparation of PUPCMs and their composites was very simple, inexpensive, environmental friendly and easy to process into desired shapes, which could find the promising applications in solar

DEVELOPMENT OF MODEL FOR QUANTITATIVE EVALUATION OF DYNAMICALLY STABLE FORMS OF RIVER CHANNELS

Directory of Open Access Journals (Sweden)

O. V. Zenkin

2017-01-01

Full Text Available The article highlights the method of calculating the optimum curvature of the river channels using the kinematic model of the flow structure based on the concept of discrete nature of the channel process. It offers the analytic form of the equation of motion of river flow, which can be used simulation modeling for searching dynamically stable form of the river channel, and which can control water level in rivers. The source data for the illustrations of given in the article modeling methods have been served the images received from MODIS on the Terra satellite, for the lower reaches of the river Kur, which merges with the river Urmi, forming the Tunguska river – the left tributary of the Amur.The modified geometric method can be used to calculate obliquity of tangent to the curve and normal in those situations when observed on satellite imagery points are located on the coordinate of the network irregularly and when three points lying on the curve of the riverbed do not form isosceles triangle.The model assembles tangential and radial components of the forces acting on the water flow (centrifugal, friction and gravity. Curvature radius is explicitly expressed in the model through the parameter  – gradient angle relative to the axis X. As solution for the value of the angle  is searched, when the correlation function reaches its maximum. It is assumed that the riverbed shape “wrong” and could be modified so that the resulting curve better correlated with calculated curve. Morphometric dependences for macroforms allow creating series of morphological methods for the calculation of deformations and displacement of the shore in any section of meander scroll.The proposed technique has been tested also on satellite imagery of high resolution. The presented methods of calculation are used as the basis for hydrological projects of geoinformation systems oriented at prediction of morphodynamic processes and morphological evolution of river

INTERPOLYELECTROLYTE COMPLEXES AS PROSPECTIVE CARRIERS FOR CONTROLLED DRUG DELIVERY

OpenAIRE

Kaur Jasmeet; Harikumar S.L.; Kaur Amanpreet

2012-01-01

In the current scenario, polymers as carriers have revolutionized the drug delivery system. A more successful approach, to exploit the different properties of polymers in a solitary system is the complexation of polymers to form polyelectrolyte complexes. These complexes circumvent the use of chemical crosslinking agents, thereby reducing the risk of toxicity. The complex formed is generally applied in different dosage forms for the formulation of stable aggregated macromolecules. There are t...

Malachite green mediates homodimerization of antibody VL domains to form a fluorescent ternary complex with singular symmetric interfaces

Science.gov (United States)

Szent-Gyorgyi, Chris; Stanfield, Robyn L.; Andreko, Susan; Dempsey, Alison; Ahmed, Mushtaq; Capek, Sara; Waggoner, Alan; Wilson, Ian A.; Bruchez, Marcel P.

2013-01-01

We report that a symmetric small molecule ligand mediates the assembly of antibody light chain variable domains (VLs) into a correspondent symmetric ternary complex with novel interfaces. The L5* Fluorogen Activating Protein (FAP) is a VL domain that binds malachite green dye (MG) to activate intense fluorescence. Crystallography of liganded L5* reveals a 2:1 protein:ligand complex with inclusive C2 symmetry, where MG is almost entirely encapsulated between an antiparallel arrangement of the two VL domains. Unliganded L5* VL domains crystallize as a similar antiparallel VL/VL homodimer. The complementarity determining regions (CDRs) are spatially oriented to form novel VL/VL and VL/ligand interfaces that tightly constrain a propeller conformer of MG. Binding equilibrium analysis suggests highly cooperative assembly to form a very stable VL/MG/VL complex, such that MG behaves as a strong chemical inducer of dimerization. Fusion of two VL domains into a single protein tightens MG binding over 1,000-fold to low picomolar affinity without altering the large binding enthalpy, suggesting that bonding interactions with ligand and restriction of domain movements make independent contributions to binding. Fluorescence activation of a symmetrical fluorogen provides a selection mechanism for the isolation and directed evolution of ternary complexes where unnatural symmetric binding interfaces are favored over canonical antibody interfaces. As exemplified by L5*, these self-reporting complexes may be useful as modulators of protein association or as high affinity protein tags and capture reagents. PMID:23978698

Stable isotope probing to study functional components of complex microbial ecosystems.

Science.gov (United States)

Mazard, Sophie; Schäfer, Hendrik

2014-01-01

This protocol presents a method of dissecting the DNA or RNA of key organisms involved in a specific biochemical process within a complex ecosystem. Stable isotope probing (SIP) allows the labelling and separation of nucleic acids from community members that are involved in important biochemical transformations, yet are often not the most numerically abundant members of a community. This pure culture-independent technique circumvents limitations of traditional microbial isolation techniques or data mining from large-scale whole-community metagenomic studies to tease out the identities and genomic repertoires of microorganisms participating in biological nutrient cycles. SIP experiments can be applied to virtually any ecosystem and biochemical pathway under investigation provided a suitable stable isotope substrate is available. This versatile methodology allows a wide range of analyses to be performed, from fatty-acid analyses, community structure and ecology studies, and targeted metagenomics involving nucleic acid sequencing. SIP experiments provide an effective alternative to large-scale whole-community metagenomic studies by specifically targeting the organisms or biochemical transformations of interest, thereby reducing the sequencing effort and time-consuming bioinformatics analyses of large datasets.

Epoxy-Based Organogels for Thermally Reversible Light Scattering Films and Form-Stable Phase Change Materials.

Science.gov (United States)

Puig, Julieta; Dell' Erba, Ignacio E; Schroeder, Walter F; Hoppe, Cristina E; Williams, Roberto J J

2017-03-29

Alkyl chains of β-hydroxyesters synthesized by the capping of terminal epoxy groups of diglycidylether of bisphenol A (DGEBA) with palmitic (C16), stearic (C18), or behenic (C22) fatty acids self-assemble forming a crystalline phase. Above a particular concentration solutions of these esters in a variety of solvents led to supramolecular (physical) gels below the crystallization temperature of alkyl chains. A form-stable phase change material (FS-PCM) was obtained by blending the ester derived from behenic acid with eicosane. A blend containing 20 wt % ester was stable as a gel up to 53 °C and exhibited a heat storage capacity of 161 J/g, absorbed during the melting of eicosane at 37 °C. Thermally reversible light scattering (TRLS) films were obtained by visible-light photopolymerization of poly(ethylene glycol) dimethacrylate-ester blends (50 wt %) in the gel state at room temperature. The reaction was very fast and not inhibited by oxygen. TRLS films consisted of a cross-linked methacrylic network interpenetrated by the supramolecular network formed by the esters. Above the melting temperature of crystallites formed by alkyl chains, the film was transparent due to the matching between refractive indices of the methacrylic network and the amorphous ester. Below the crystallization temperature, the film was opaque because of light dispersion produced by the organic crystallites uniformly dispersed in the material. Of high significance for application was the fact that the contrast ratio did not depend on heating and cooling rates.

Preparation and properties studies of halogen-free flame retardant form-stable phase change materials based on paraffin/high density polyethylene composites

International Nuclear Information System (INIS)

Cai Yibing; Wei Qufu; Huang Fenglin; Gao Weidong

2008-01-01

The halogen-free flame retardant form-stable phase change materials (PCM) based on paraffin/high density polyethylene (HDPE) composites were prepared by using twin-screw extruder technique. The structures and properties of the form-stable PCM composites based on intumescent flame retardant system with expandable graphite (EG) and different synergistic additives, such as ammonium polyphosphate (APP) and zinc borate (ZB) were characterized by scanning electronic microscope (SEM), thermogravimetric analyses (TGA), dynamic Fourier-transform infrared (FTIR) spectra, differential scanning calorimeter (DSC) and Cone calorimeter test. The TGA results showed that the halogen-free flame retardant form-stable PCM composites produced a larger amount of charred residue at 700 deg. C, although the onset of weight loss of the halogen-free flame retardant form-stable PCM composites occurred at a lower temperature due to the thermal decomposition of flame retardant. The DSC measurements indicated that the additives of flame retardant had little effect on the thermal energy storage property, and the temperatures of phase change peaks and the latent heat of the paraffin showed better occurrence during the freezing process. The dynamic FTIR monitoring results revealed that the breakdowns of main chains (HDPE and paraffin) and formations of various residues increased with increasing thermo-oxidation temperature. It was also found from the Cone calorimeter tests that the peak of heat release rate (PHRR) decreased significantly. Both the decrease of the PHRR and the structure of charred residue after combustion indicated that there was a synergistic effect between the EG and APP, contributing to the improved flammability of the halogen-free flame retardant form-stable PCM composites

Synthesis and luminescence properties of hybrid organic-inorganic transparent titania thin film activated by in- situ formed lanthanide complexes

Science.gov (United States)

Wang, Yige; Wang, Li; Li, Huanrong; Liu, Peng; Qin, Dashan; Liu, Binyuan; Zhang, Wenjun; Deng, Ruiping; Zhang, Hongjie

2008-03-01

Stable transparent titania thin films were fabricated at room temperature by combining thenoyltrifluoroacetone (TTFA)-modified titanium precursors with amphiphilic triblock poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO, P123) copolymers. The obtained transparent titania thin films were systematically investigated by IR spectroscopy, PL emission and excitation spectroscopy and transmission electron microscopy. IR spectroscopy indicates that TTFA coordinates the titanium center during the process of hydrolysis and condensation. Luminescence spectroscopy confirms the in-situ formation of lanthanide complexes in the transparent titania thin film. TEM image shows that the in-situ formed lanthanide complexes were homogeneously distributed throughout the whole thin film. The quantum yield and the number of water coordinated to lanthanide metal center have been theoretically determined based on the luminescence data.

THE COMPACT STAR-FORMING COMPLEX AT THE HEART OF NGC 253

Energy Technology Data Exchange (ETDEWEB)

Davidge, T. J., E-mail: tim.davidge@nrc.ca [Dominion Astrophysical Observatory, National Research Council of Canada, 5071 West Saanich Road, Victoria, BC V9E 2E7 (Canada)

2016-02-20

We discuss integral field spectra of the compact star-forming complex that is the brightest near-infrared (NIR) source in the central regions of the starburst galaxy NGC 253. The spectra cover the H and K passbands and were recorded with the Gemini NIR Spectrograph during subarcsecond seeing conditions. Absorption features in the spectrum of the star-forming complex are weaker than in the surroundings. An absorption feature is found near 1.78 μm that coincides with the location of a C{sub 2} bandhead. If this feature is due to C{sub 2} then the star-forming complex has been in place for at least a few hundred Myr. Emission lines of Brγ, [Fe ii], and He i 2.06 μm do not track the NIR continuum light. Pockets of star-forming activity that do not have associated concentrations of red supergiants, and so likely have ages <8 Myr, are found along the western edge of the complex, and there is evidence that one such pocket contains a rich population of Wolf–Rayet stars. Unless the star-forming complex is significantly more metal-poor than the surroundings, then a significant fraction of its total mass is in stars with ages <8 Myr. If the present-day star formation rate is maintained then the timescale to double its stellar mass ranges from a few Myr to a few tens of Myr, depending on the contribution made by stars older than ∼8 Myr. If—as suggested by some studies—the star-forming complex is centered on the galaxy’s nucleus, which presumably contains a large population of old and intermediate-age stars, then the nucleus of NGC 253 is currently experiencing a phase of rapid growth in its stellar mass.

Form-stable paraffin/high density polyethylene composites as solid-liquid phase change material for thermal energy storage: preparation and thermal properties

International Nuclear Information System (INIS)

Sari, Ahmet

2004-01-01

This paper deals with the preparation of paraffin/high density polyethylene (HDPE) composites as form-stable, solid-liquid phase change material (PCM) for thermal energy storage and with determination of their thermal properties. In such a composite, the paraffin (P) serves as a latent heat storage material and the HDPE acts as a supporting material, which prevents leakage of the melted paraffin because of providing structural strength. Therefore, it is named form-stable composite PCM. In this study, two kinds of paraffins with melting temperatures of 42-44 deg. C (type P1) and 56-58 deg. C (type P2) and latent heats of 192.8 and 212.4 J g -1 were used. The maximum weight percentage for both paraffin types in the PCM composites without any seepage of the paraffin in the melted state were found as high as 77%. It is observed that the paraffin is dispersed into the network of the solid HDPE by investigation of the structure of the composite PCMs using a scanning electronic microscope (SEM). The melting temperatures and latent heats of the form-stable P1/HDPE and P2/HDPE composite PCMs were determined as 37.8 and 55.7 deg. C, and 147.6 and 162.2 J g -1 , respectively, by the technique of differential scanning calorimetry (DSC). Furthermore, to improve the thermal conductivity of the form-stable P/HDPE composite PCMs, expanded and exfoliated graphite (EG) by heat treatment was added to the samples in the ratio of 3 wt.%. Thereby, the thermal conductivity was increased about 14% for the form-stable P1/HDPE and about 24% for the P2/HDPE composite PCMs. Based on the results, it is concluded that the prepared form-stable P/HDPE blends as composite type PCM have great potential for thermal energy storage applications in terms of their satisfactory thermal properties and improved thermal conductivity. Furthermore, these composite PCMs added with EG can be considered cost effective latent heat storage materials since they do not require encapsulation and extra cost to enhance

Polymorphic drugs examined with neutron spectroscopy: Is making more stable forms really that simple?

Science.gov (United States)

Tsapatsaris, Nikolaos; Landsgesell, Sven; Koza, Michael M.; Frick, Bernhard; Boldyreva, Elena V.; Bordallo, Heloisa N.

2013-12-01

Understanding polymorphism in pharmaceutical ingredients is a long-standing challenge in formulation science. A well-known example is paracetamol, C8H9NO2. The marketed stable form I crystallizes with corrugated molecular layers. In contrast, form II, which is thermodynamically favorable at high pressures, has relatively planar layers that can slip over each other without difficulty, but is metastable at ambient conditions. By means of inelastic neutron scattering we demonstrated that the lattice modes of form II exhibit a sudden 1 meV energy shift at 300 K under a pressure of ca 0.4 GPa. Moreover, evidence of an increase of the vibrational energy in both polymorphs was found, which was accompanied, in form I, by an unexpectedly weak increase of the tunnel splitting. These results indicate an anisotropy of the potential surface probed by the methyl rotor, and are discussed in relation to the differences of the strength of the hydrogen bond environment for each polymorph.

Secondary Teachers' Conception of Various Forms of Complex Numbers

Science.gov (United States)

Karakok, Gulden; Soto-Johnson, Hortensia; Dyben, Stephenie Anderson

2015-01-01

This study explores in-service high school mathematics teachers' conception of various forms of complex numbers and ways in which they transition between different representations of these forms. One 90-min interview was conducted with three high school mathematics teachers after they completed three professional development sessions, each 4 h, on…

Synthesis and physicochemical characterization of rhenium (V) complexes with bisbenzoylthiosemicarbazones

International Nuclear Information System (INIS)

Gagieva, S.Ch.; Gutnova, N.A.; Tsaloev, A.T.; Khubulov, A.B.; Arutyunyants, A.A.; Galimov, Yu.B.

2003-01-01

Rhenium (V) complexing with mono- and bis-benzoylthiosemicarbazones is studied in dependence on hydrohalic acids concentration changes. It is determined that in media with high concentration of hydrohalic acids (6 mol/l HCl, 7 mol/l HBr) in dependence on reaction conditions stable complexes with bi- and tridentate coordination of thiosemicarbazone are formed. In the case of hydrohalic acid concentration decreasing stable binuclear and oxohydroxycomplexes are formed. Composition and structure of the compounds obtained are determined by the methods of element analysis, IR spectroscopy, conductometry. Thermal investigations of the compounds obtained are done [ru

Purification of Ovine Respiratory Complex I Results in a Highly Active and Stable Preparation*

Science.gov (United States)

Letts, James A.; Degliesposti, Gianluca; Fiedorczuk, Karol; Skehel, Mark; Sazanov, Leonid A.

2016-01-01

NADH-ubiquinone oxidoreductase (complex I) is the largest (∼1 MDa) and the least characterized complex of the mitochondrial electron transport chain. Because of the ease of sample availability, previous work has focused almost exclusively on bovine complex I. However, only medium resolution structural analyses of this complex have been reported. Working with other mammalian complex I homologues is a potential approach for overcoming these limitations. Due to the inherent difficulty of expressing large membrane protein complexes, screening of complex I homologues is limited to large mammals reared for human consumption. The high sequence identity among these available sources may preclude the benefits of screening. Here, we report the characterization of complex I purified from Ovis aries (ovine) heart mitochondria. All 44 unique subunits of the intact complex were identified by mass spectrometry. We identified differences in the subunit composition of subcomplexes of ovine complex I as compared with bovine, suggesting differential stability of inter-subunit interactions within the complex. Furthermore, the 42-kDa subunit, which is easily lost from the bovine enzyme, remains tightly bound to ovine complex I. Additionally, we developed a novel purification protocol for highly active and stable mitochondrial complex I using the branched-chain detergent lauryl maltose neopentyl glycol. Our data demonstrate that, although closely related, significant differences exist between the biochemical properties of complex I prepared from ovine and bovine mitochondria and that ovine complex I represents a suitable alternative target for further structural studies. PMID:27672209

Distribution tactics for success in turbulent versus stable environments: A complexity theory approach

Directory of Open Access Journals (Sweden)

Roger Bruce Mason

2013-11-01

Full Text Available This article proposes that the external environment influences the choice of distribution tactics. Since businesses and markets are complex adaptive systems, using complexity theory to understand such environments is necessary, but it has not been widely researched. A qualitative case method using in-depth interviews investigated four successful, versus less successful, companies in turbulent versus stable environments. The results tentatively confirmed that the more successful company, in a turbulent market, sees distribution activities as less important than other aspects of the marketing mix, but uses them to stabilise customer relationships and to maintain distribution processes. These findings can benefit marketers by emphasising a new way to consider place activities. How marketers can be assisted, and suggestions for further research, are provided.

PEG/SiO{sub 2}–Al{sub 2}O{sub 3} hybrid form-stable phase change materials with enhanced thermal conductivity

Energy Technology Data Exchange (ETDEWEB)

Tang, Bingtao, E-mail: tangbt@dlut.edu.cn; Wu, Cheng; Qiu, Meige; Zhang, Xiwen; Zhang, Shufen

2014-03-01

The thermal conductivity of form-stable PEG/SiO{sub 2} phase change material (PCM) was enhanced by in situ doping of Al{sub 2}O{sub 3} using an ultrasound-assisted sol–gel method. Fourier transform infrared spectroscopy (FT-IR) was used to characterize the structure, and the crystal performance was characterized by the X-ray diffraction (XRD). Differential scanning calorimetry (DSC) and thermogravimetric analyzer (TGA) were used to determine the thermal properties. The phase change enthalpy of PEG/SiO{sub 2}–Al{sub 2}O{sub 3} reached 124 J g{sup −1}, and thermal conductivity improved by 12.8% for 3.3 wt% Al{sub 2}O{sub 3} in the PCM compared with PEG/SiO{sub 2}. The hybrid PCM has excellent thermal stability and form-stable effects. - Highlights: • The PEG/SiO{sub 2}–Al{sub 2}O{sub 3} hybrid form-stable phase change material (PCM) was obtained through the sol–gel method. • The inexpensive aluminum nitrate and tetraethyl orthosilicate were used as sol precursors. • This organic–inorganic hybrid process can effectively enhance the thermal conductivity of PCMs. • The PCM exhibited high thermal stability and excellent form-stable effects.

Estimation of stability of polynuclear rare earth complexes with EDTA in the presence of stable monocomplexonates

International Nuclear Information System (INIS)

Le Ba Tkhun; Kupriyanova, G.N.; Smirnova, N.S.; Martynenko, L.I.; Evseeva, A.M.

1987-01-01

Complexing in rare-earth-EDTA system at the mole ratio making up (M 3+ ):(H 2 A 2- )=1:1, 2:1, 5:1, (M=Nd, Yb), C H 2 A 2- =0.010, 0.015 mol/l, μ=0.5 (KCl) is studied in pH 1.6-3.0 interval by pH-metric titration technique using mathematical modelling method. A model containing MA - , MHA, M 2 A 2+ complexes for which stability constants, equalling respectively (lgK) to 15.66, 2.11, 1.06 (for neodymium complexes) and 18.70, 1.78, 0.45 (for ytterbium complexes) are determined by non-linear LSF, appears to be adequate. It is shown that binuclear complex concentration in solution with M 3+ excess is comparable to stable monocomplexonate concentration

Extrapolation of π-meson form factor, zeros in the analyticity domain

International Nuclear Information System (INIS)

Morozov, P.T.

1978-01-01

The problem of a stable extrapolation from the cut to an arbitrary interior of the analyticity domain for the pion form factor is formulated and solved. As it is shown a stable solution can be derived if module representations with the Karleman weight function are used as the analyticity conditions. The case when the form factor has zeros is discussed. If there are zeros in the complex plane they must be taken into account when determining the extrapolation function

Purification of Ovine Respiratory Complex I Results in a Highly Active and Stable Preparation.

Science.gov (United States)

Letts, James A; Degliesposti, Gianluca; Fiedorczuk, Karol; Skehel, Mark; Sazanov, Leonid A

2016-11-18

NADH-ubiquinone oxidoreductase (complex I) is the largest (∼1 MDa) and the least characterized complex of the mitochondrial electron transport chain. Because of the ease of sample availability, previous work has focused almost exclusively on bovine complex I. However, only medium resolution structural analyses of this complex have been reported. Working with other mammalian complex I homologues is a potential approach for overcoming these limitations. Due to the inherent difficulty of expressing large membrane protein complexes, screening of complex I homologues is limited to large mammals reared for human consumption. The high sequence identity among these available sources may preclude the benefits of screening. Here, we report the characterization of complex I purified from Ovis aries (ovine) heart mitochondria. All 44 unique subunits of the intact complex were identified by mass spectrometry. We identified differences in the subunit composition of subcomplexes of ovine complex I as compared with bovine, suggesting differential stability of inter-subunit interactions within the complex. Furthermore, the 42-kDa subunit, which is easily lost from the bovine enzyme, remains tightly bound to ovine complex I. Additionally, we developed a novel purification protocol for highly active and stable mitochondrial complex I using the branched-chain detergent lauryl maltose neopentyl glycol. Our data demonstrate that, although closely related, significant differences exist between the biochemical properties of complex I prepared from ovine and bovine mitochondria and that ovine complex I represents a suitable alternative target for further structural studies. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

Alanine water complexes.

Science.gov (United States)

Vaquero, Vanesa; Sanz, M Eugenia; Peña, Isabel; Mata, Santiago; Cabezas, Carlos; López, Juan C; Alonso, José L

2014-04-10

Two complexes of alanine with water, alanine-(H2O)n (n = 1,2), have been generated by laser ablation of the amino acid in a supersonic jet containing water vapor and characterized using Fourier transform microwave spectroscopy. In the observed complexes, water molecules bind to the carboxylic group of alanine acting as both proton donors and acceptors. In alanine-H2O, the water molecule establishes two intermolecular hydrogen bonds forming a six-membered cycle, while in alanine-(H2O)2 the two water molecules establish three hydrogen bonds forming an eight-membered ring. In both complexes, the amino acid moiety is in its neutral form and shows the conformation observed to be the most stable for the bare molecule. The microsolvation study of alanine-(H2O)n (n = 1,2) can be taken as a first step toward understanding bulk properties at a microscopic level.

ATP forms a stable complex with the essential histidine kinase WalK (YycG) domain

Energy Technology Data Exchange (ETDEWEB)

Celikel, Reha; Veldore, Vidya Harini [University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205 (United States); Mathews, Irimpan [Stanford Synchrotron Radiation Lightsource, 2575 Sand Hill Road, Menlo Park, CA 94025 (United States); Devine, Kevin M., E-mail: kdevine@tcd.ie [Trinity College Dublin, Dublin 2 (Ireland); Varughese, Kottayil I., E-mail: kdevine@tcd.ie [University of Arkansas for Medical Sciences, 4301 West Markham Street, Little Rock, AR 72205 (United States)

2012-07-01

The histidine WalK (YycG) plays a crucial role in coordinating murein synthesis with cell division and the crystal structure of its ATP binding domain has been determined. Interestingly the bound ATP was not hydrolyzed during crystallization and remains intact in the crystal lattice. In Bacillus subtilis, the WalRK (YycFG) two-component system coordinates murein synthesis with cell division. It regulates the expression of autolysins that function in cell-wall remodeling and of proteins that modulate autolysin activity. The transcription factor WalR is activated upon phosphorylation by the histidine kinase WalK, a multi-domain homodimer. It autophosphorylates one of its histidine residues by transferring the γ-phosphate from ATP bound to its ATP-binding domain. Here, the high-resolution crystal structure of the ATP-binding domain of WalK in complex with ATP is presented at 1.61 Å resolution. The bound ATP remains intact in the crystal lattice. It appears that the strong binding interactions and the nature of the binding pocket contribute to its stability. The triphosphate moiety of ATP wraps around an Mg{sup 2+} ion, providing three O atoms for coordination in a near-ideal octahedral geometry. The ATP molecule also makes strong interactions with the protein. In addition, there is a short contact between the exocyclic O3′ of the sugar ring and O2B of the β-phosphate, implying an internal hydrogen bond. The stability of the WalK–ATP complex in the crystal lattice suggests that such a complex may exist in vivo poised for initiation of signal transmission. This feature may therefore be part of the sensing mechanism by which the WalRK two-component system is so rapidly activated when cells encounter conditions conducive for growth.

Form-Stable Phase Change Materials Based on Eutectic Mixture of Tetradecanol and Fatty Acids for Building Energy Storage: Preparation and Performance Analysis

Directory of Open Access Journals (Sweden)

Yiran li

2013-10-01

Full Text Available This paper is focused on preparation and performance analysis of a series of form-stable phase change materials (FSPCMs, based on eutectic mixtures as phase change materials (PCMs for thermal energy storage and high-density polyethylene (HDPE-ethylene-vinyl acetate (EVA polymer as supporting materials. The PCMs were eutectic mixtures of tetradecanol (TD–capric acid (CA, TD–lauric acid (LA, and TD–myristic acid (MA, which were rarely explored before. Thermal properties of eutectic mixtures and FSPCMs were measured by differential scanning calorimeter (DSC. The onset melting/solidification temperatures of form-stable PCMs were 19.13 °C/13.32 °C (FS TD–CA PCM, 24.53 °C/24.92 °C (FS TD–LA PCM, and 33.15 °C/30.72 °C (FS TD–MA PCM, respectively, and latent heats were almost greater than 90 J/g. The surface morphologies and chemical stability of form-stable PCM were surveyed by scanning electron microscopy (SEM and Fourier-transform infrared (FT-IR spectroscopy, respectively. The thermal cycling test revealed that the thermal reliability of these three form-stable PCMs was good. Thermal storage/release experiment indicated melting/solidification time was shortened by introducing 10 wt % aluminum powder (AP. It is concluded that these FSPCMs can act as potential building thermal storage materials in terms of their satisfactory thermal properties.

Form-Stable Phase Change Materials Based on Eutectic Mixture of Tetradecanol and Fatty Acids for Building Energy Storage: Preparation and Performance Analysis.

Science.gov (United States)

Huang, Jingyu; Lu, Shilei; Kong, Xiangfei; Liu, Shangbao; Li, Yiran

2013-10-22

This paper is focused on preparation and performance analysis of a series of form-stable phase change materials (FSPCMs), based on eutectic mixtures as phase change materials (PCMs) for thermal energy storage and high-density polyethylene (HDPE)-ethylene-vinyl acetate (EVA) polymer as supporting materials. The PCMs were eutectic mixtures of tetradecanol (TD)-capric acid (CA), TD-lauric acid (LA), and TD-myristic acid (MA), which were rarely explored before. Thermal properties of eutectic mixtures and FSPCMs were measured by differential scanning calorimeter (DSC). The onset melting/solidification temperatures of form-stable PCMs were 19.13 °C/13.32 °C (FS TD-CA PCM), 24.53 °C/24.92 °C (FS TD-LA PCM), and 33.15 °C/30.72 °C (FS TD-MA PCM), respectively, and latent heats were almost greater than 90 J/g. The surface morphologies and chemical stability of form-stable PCM were surveyed by scanning electron microscopy (SEM) and Fourier-transform infrared (FT-IR) spectroscopy, respectively. The thermal cycling test revealed that the thermal reliability of these three form-stable PCMs was good. Thermal storage/release experiment indicated melting/solidification time was shortened by introducing 10 wt % aluminum powder (AP). It is concluded that these FSPCMs can act as potential building thermal storage materials in terms of their satisfactory thermal properties.

Strategic directions of personnel potential forming of a building complex

Directory of Open Access Journals (Sweden)

Simonova Marina

2016-01-01

Full Text Available The analysis of directions of strategic approach forming of labor potential management of a building complex is carried out in this paper. On the basis of this analysis the system of actions for strategy forming divided into consecutive stages is offered. The development of the personnel forecast is a strategic planning basis. One of personnel forecast variants is the correlation of needs estimates in personnel of a building complex with available allowances. On the basis of the personnel forecast strategic analysis it is possible to compose working programs for the stated goals of implementation. Operational assessment of personnel requirements of a building complex is proved to be combined with strategic objectives. Some assessment approaches to qualitative and quantitative need for specialists of a building complex are offered. The fact that high-quality labor power supply system of a building complex with should be based on industry development forecast and increase in construction products competitiveness is revealed in the article. Strategic management priority will allow to react immediately to the current situation changes, to introduce amendments both into tactical, and operational management.

Platinated DNA oligonucleotides: new probes forming ultrastable conjugates with graphene oxide

Science.gov (United States)

Wang, Feng; Liu, Juewen

2014-05-01

Metal containing polymers have expanded the property of polymers by involving covalently associated metal complexes. DNA is a special block copolymer. While metal ions are known to influence DNA, little is explored on its polymer property when strong metal complexes are associated. In this work, we study cisplatin modified DNA as a new polymer and probe. Out of the complexes formed between cisplatin-A15, HAuCl4-A15, Hg2+-T15 and Ag+-C15, only the cisplatin adduct is stable under the denaturing gel electrophoresis condition. Each Pt-nucleobase bond gives a positive charge and thus makes DNA a zwitterionic polymer. This allows ultrafast adsorption of DNA by graphene oxide (GO) and the adsorbed complex is highly stable. Non-specific DNA, protein, surfactants and thiolated compounds cannot displace platinated DNA from GO, while non-modified DNA is easily displaced in most cases. The stable GO/DNA conjugate is further tested for surface hybridization. This is the first demonstration of using metallated DNA as a polymeric material for interfacing with nanoscale materials.Metal containing polymers have expanded the property of polymers by involving covalently associated metal complexes. DNA is a special block copolymer. While metal ions are known to influence DNA, little is explored on its polymer property when strong metal complexes are associated. In this work, we study cisplatin modified DNA as a new polymer and probe. Out of the complexes formed between cisplatin-A15, HAuCl4-A15, Hg2+-T15 and Ag+-C15, only the cisplatin adduct is stable under the denaturing gel electrophoresis condition. Each Pt-nucleobase bond gives a positive charge and thus makes DNA a zwitterionic polymer. This allows ultrafast adsorption of DNA by graphene oxide (GO) and the adsorbed complex is highly stable. Non-specific DNA, protein, surfactants and thiolated compounds cannot displace platinated DNA from GO, while non-modified DNA is easily displaced in most cases. The stable GO/DNA conjugate

Colchiceine Complexes with Lithium, Sodium and Potassium Salts − Spectroscopic Studies

Directory of Open Access Journals (Sweden)

Joanna Kurek

2016-09-01

Full Text Available Colchiceine complexes with Li+, Na+ and K+ cations have been synthesized and studied by 1H and 13C NMR, FT-IR, FAB MS and UV-Vis. It has been shown that colchiceine forms stable complexes especially with lithium cation and the most stable structures of the complexes are those in which the acetamide groups are involved in the coordination process. The structures of the colchiceine complexes with Li+, Na+ and K+ cations are discussed in details. This work is licensed under a Creative Commons Attribution 4.0 International License.

Utility of Lithium in Rare-Earth Metal Reduction Reactions to Form Nontraditional Ln2+ Complexes and Unusual [Li(2.2.2-cryptand)]1+ Cations.

Science.gov (United States)

Huh, Daniel N; Darago, Lucy E; Ziller, Joseph W; Evans, William J

2018-02-19

The utility of lithium compared to other alkali metals in generating Ln 2+ rare-earth metal complexes via reduction of Ln 3+ precursors in reactions abbreviated as LnA 3 /M (Ln = rare-earth metal; A = anionic ligand; M = alkali metal) is described. Lithium reduction of Cp' 3 Ln (Cp' = C 5 H 4 SiMe 3 ; Ln = Y, Tb, Dy, Ho) under Ar in the presence of 2.2.2-cryptand (crypt) forms new examples of crystallographically characterizable Ln 2+ complexes of these metals, [Li(crypt)][Cp' 3 Ln]. In each complex, lithium is found in an N 2 O 4 donor atom coordination geometry that is unusual for the cryptand ligand. Magnetic susceptibility data on these new examples of nontraditional divalent lanthanide complexes are consistent with 4f n 5d 1 electronic configurations. The Dy and Ho complexes have exceptionally high single-ion magnetic moments, 11.35 and 11.67 μ B , respectively. Lithium reduction of Cp' 3 Y under N 2 at -35 °C forms the Y 2+ complex (Cp' 3 Y) 1- , which reduces dinitrogen upon warming to room temperature to generate the (N 2 ) 2- complex [Cp' 2 Y(THF)] 2 (μ-η 2 :η 2 -N 2 ). These results provide insight on the factors that lead to reduced dinitrogen complexes and/or stable divalent lanthanide complexes as a function of the specific reducing agent and conditions.

Lys and Arg in UBI: A specific site for a stable Tc-99m complex?

International Nuclear Information System (INIS)

Melendez-Alafort, Laura; Ramirez, Flor de Maria; Ferro-Flores, Guillermina; Murphy, Consuelo Arteaga de; Pedraza-Lopez, Martha; Hnatowich, Donald J.

2003-01-01

The aim of this study was to help establish if ubiquicidin peptide 29-41 fragment (UBI) contains a specific site for 99m Tc labeling by a new direct method under alkaline conditions. Since this peptide does not have cysteine residues, it is possible that neighboring arginine and lysine in the peptide amino acid sequence (Thr-Gly-Arg-Ala-Lys-Arg-Arg-Met-Gln-Tyr-Asn-Arg-Arg) could be a specific coordination site to form a stable 99m Tc-UBI complex. Following direct labeling, the in vitro stability of 99m Tc-UBI was compared to UBI radiolabeled by one indirect method using HYNIC/tricine and HYNIC/tricine/EDDA. Radiochemical purity of 99m Tc-UBI averaged 97% compared to 88% for 99m Tc-HYNIC-UBI/tricine and 98% for 99m Tc-HYNIC-UBI/tricine/EDDA. Both 99m Tc-HYNIC-UBI (tricine or EDDA) and 99m Tc-UBI showed stability in human serum and solutions of cysteine. 99m Tc-UBI radiochemical purity 24 h after dilution in 0.9% NaCl was greater than 90% at pH 9 and greater than 95% at pH 6.5. Under one set of experimental conditions, in vitro binding to bacteria of 99m Tc-UBI was 35% and identical to that of 99m Tc-HYNIC-UBI/tricine and 99m Tc-HYNIC-UBI/tricine/EDDA at 32% and 31% respectively. The biodistribution of 99m Tc-UBI in mice showed a rapid renal clearance. To help identify the site(s) of 99m Tc binding following direct labeling, molecular mechanics and quantum-mechanical calculations were performed which showed that the amine groups of Arg 7 and Lys are the most probable site. The calculations show that these groups can form a square pyramid with two water molecules for the Tc cation (dxysp 3 ). It will be necessary to isolate and characterize the 99 Tc(V)(O)-UBI . (H 2 O) n complex to confirm these results

A novel stable 3D luminescent uranyl complex for highly efficient and sensitive recognition of Ru3+ and biomolecules

Science.gov (United States)

Tian, Hong-Hong; Chen, Liang-Ting; Zhang, Rong-Lan; Zhao, Jian-She; Liu, Chi-Yang; Weng, Ng Seik

2018-02-01

A novel highly stable 3D luminescent uranyl coordination polymer, namely {[UO2(L)]·DMA}n (1), was assembled with uranyl salt and a glycine-derivative ligand [6-(carboxymethyl-amino)-4-oxo-4,5-dihydro-[1,3,5]triazin-2-ylamino]-acetic acid (H2L) under solvothermal reaction. Besides, It was found that complex 1 possesses excellent luminescent properties, particularly the efficient selectivity and sensitivity in the recognition of Ru3+, biomacromolecule bovine serum albumin (BSA), biological small molecules dopamine (DA), ascorbic acid (AA) and uric acid (UA) in the water solution based on a "turn-off" mechanism. Accordingly, the luminescent explorations also demonstrated that complex 1 could be acted as an efficient luminescent probe with high quenching efficiency and low detection limit for selectively detecting Ru3+ and biomolecules (DA, AA, UA and BSA). It was noted that the framework structure of complex 1 still remains highly stable after quenching, which was verified by powder X-ray diffraction (PXRD).

Preparation, thermal and flammability properties of a novel form-stable phase change materials based on high density polyethylene/poly(ethylene-co-vinyl acetate)/organophilic montmorillonite nanocomposites/paraffin compounds

International Nuclear Information System (INIS)

Cai Yibing; Song Lei; He Qingliang; Yang Dandan; Hu Yuan

2008-01-01

The paraffin is one of important thermal energy storage materials with many desirable characteristics (i.e., high heat of fusion, varied phase change temperature, negligible supercooling, self-nucleating, no phase segregation and cheap, etc.), but has low thermal stability and flammable. Hence, a novel form-stable phase change materials (PCM) based on high density polyethylene (HDPE)/poly(ethylene-co-vinyl acetate) (EVA)/organophilic montmorillonite (OMT) nanocomposites and paraffin are prepared by twin-screw extruder technique. The structures of the HDPE-EVA/OMT nanocomposites and the form-stable PCM are evidenced by the X-ray diffraction (XRD), transmission electronic microscopy (TEM) and scanning electronic microscope (SEM). The results of XRD and TEM show that the HDPE-EVA/OMT nanocomposites form the ordered intercalated nanomorphology. The form-stable PCM consists of the paraffin, which acts as a dispersed phase change material and the HDPE-EVA/OMT nanocomposites, which acts as the supporting material. The paraffin disperses in the three-dimensional net structure formed by HDPE-EVA/OMT nanocomposites. The thermal stability, latent heat and flammability properties are characterized by thermogravimetry analysis (TGA), dynamic Fourier-transform infrared (FTIR), differential scanning calorimeter (DSC) and cone calorimeter, respectively. The TGA and dynamic FTIR analyses indicate that the incorporation of suitable amount of OMT into the form-stable PCM increase the thermal stability. The DSC results show that the latent heat of the form-stable PCM has a certain degree decrease. The cone calorimeter shows that the heat release rate (HRR) has remarkably decreases with loading of OMT in the form-stable PCM, contributing to the improved flammability properties

Mobility of organic complexes of some non-TRU fission and activation products: a selective review

Energy Technology Data Exchange (ETDEWEB)

Wiggins, D.J.; Franz, J.A.

1978-05-01

Zr, Nb, Ni, and possibly Tc are mobile in the presence of aqueous organic complexing agents to a certain extent. Low pH appears to be required for efficient complex formations with organic ligands in aqueous media. Zr complexes with a number of synthetic chelating agents such as EDTA, and DTPA to form stable, water-soluble complexes in acidic and neutral aqueous systems. Zr also complexes with HIMDA or HXG to form a stable, water soluble complex in any aqueous system and with ..cap alpha..-hydroxy carboxylic acids in alkaline aqueous systems. Uncomplexed Zr would be readily absorbed by or precipitated on soil. It is predicted that the organic complexes of Zr would be absorbed less by soil than uncomplexed zirconium. Nb generally forms the most stable complexes with nitrogen containing chelating ligands such as EDTA, and less stable complexes with ..cap alpha..-hydroxy carboxylic acids and monodentate ligands. Uncomplexed Nb would be efficiently absorbed by or precipitated on soil from aqueous systems. Despite the high stability constants of complexed Nb, one would predict that organic complexes of niobium would be absorbed by soil because of hydrolysis of complexed Nb to insoluble hydrous niobium oxide. Ni complexes strongly with a number of oxygen and nitrogen containing organic ligands. Uncomplexed Ni is absorbed by soil in acidic and neutral aqueous systems and precipitated on soil in alkaline aqueous systems. Two complexes of Ni are known to be absorbed to a much lesser extent by soil (Ni-DTPA, Ni-EDTA). Fulvic acid and synthetic chelating agents are known to greatly enhance the movement of Ni in soil and to reduce Ni absorption by soil. Tc complexes with organic ligands in a reducing environment but the behavior of these complexes in a nonreducing environment is unknown. 8 tables, 3 figs. 62 refs.

Mobility of organic complexes of some non-TRU fission and activation products: a selective review

International Nuclear Information System (INIS)

Wiggins, D.J.; Franz, J.A.

1978-05-01

Zr, Nb, Ni, and possibly Tc are mobile in the presence of aqueous organic complexing agents to a certain extent. Low pH appears to be required for efficient complex formations with organic ligands in aqueous media. Zr complexes with a number of synthetic chelating agents such as EDTA, and DTPA to form stable, water-soluble complexes in acidic and neutral aqueous systems. Zr also complexes with HIMDA or HXG to form a stable, water soluble complex in any aqueous system and with α-hydroxy carboxylic acids in alkaline aqueous systems. Uncomplexed Zr would be readily absorbed by or precipitated on soil. It is predicted that the organic complexes of Zr would be absorbed less by soil than uncomplexed zirconium. Nb generally forms the most stable complexes with nitrogen containing chelating ligands such as EDTA, and less stable complexes with α-hydroxy carboxylic acids and monodentate ligands. Uncomplexed Nb would be efficiently absorbed by or precipitated on soil from aqueous systems. Despite the high stability constants of complexed Nb, one would predict that organic complexes of niobium would be absorbed by soil because of hydrolysis of complexed Nb to insoluble hydrous niobium oxide. Ni complexes strongly with a number of oxygen and nitrogen containing organic ligands. Uncomplexed Ni is absorbed by soil in acidic and neutral aqueous systems and precipitated on soil in alkaline aqueous systems. Two complexes of Ni are known to be absorbed to a much lesser extent by soil (Ni-DTPA, Ni-EDTA). Fulvic acid and synthetic chelating agents are known to greatly enhance the movement of Ni in soil and to reduce Ni absorption by soil. Tc complexes with organic ligands in a reducing environment but the behavior of these complexes in a nonreducing environment is unknown. 8 tables, 3 figs. 62 refs

AIMAR survey on complex forms of bronchial asthma and COPD, their management and perception of critical issues.

Science.gov (United States)

Donner, Claudio F; Visconti, Alberto

2014-01-01

The management of patients with complex forms of bronchial asthma and COPD is not usually addressed in the major international guidelines and management documents which exclusively address pure forms. AIMAR thus undertook a survey to obtain information about: a) the perceived frequency of complex forms of asthma/COPD in adult patients and in the elderly; b) patient management regarding the complex forms (focus on therapeutic goals and consequent treatment); c) the management problems perceived in diagnosis, management, monitoring, indices of appropriateness in pharmacological treatment and adherence to treatment. The survey consisted of 18 multiple choice questions, completed by means of a web-based electronic form published in internet. All the data and responses inserted in the system were checked on-line for coherence and completeness directly during the phase of insertion and each participant had one only possibility of participating. The data thus collected were memorized directly within a relational database, based on consolidated open-source MySQL technology, and thus were immediately available for examination also during the course of the survey. Access to the data, mediated by a "back office" system of interrogation and report, enabled constant monitoring of the survey as it was being carried out, as well as extractions and verification, even on smaller data sets. The survey was carried out in the full month of December 2013 and first half of January 2014. A total of 252 questionnaires were collected from the following physician groups: pneumologists (n = 180), general practitioners (GPs) (n = 32), allergologists (n = 8), internal medicine specialists (n = 20), other specialists (n = 12). Complex forms of bronchial asthma and COPD are frequently observed and considered present in variable percentages ranging from about 10% to about 50% of patients visited and considered typical of patients with a previous history of asthma. Risk factors

Self-complexity, self-evaluation, and depression: an examination of form and content within the self-schema.

Science.gov (United States)

Woolfolk, R L; Novalany, J; Gara, M A; Allen, L A; Polino, M

1995-06-01

Six studies examined the relationship between self-complexity and variables related to self-evaluation. Self-complexity was found to comprise two components: positive self-complexity and negative self-complexity. Positive self-complexity was sensitive to methodological factors, namely, variations in stimulus materials used for self-ratings. Negative self-complexity was relatively stable in the face of different rating stimuli and tasks and was related to trait measures of self-evaluation, psychic distress, and psychopathology. These findings were observed and replicated. Higher negative self-complexity was associated with increases in depression symptoms over time. Higher negative self-complexity also predicted a poorer prognosis and less complete recovery from depression in a clinical sample. Results are discussed in light of related research and possible social-cognitive mechanisms.

New glyme-cyclic imide lithium salt complexes as thermally stable electrolytes for lithium batteries

Science.gov (United States)

Tamura, Takashi; Hachida, Takeshi; Yoshida, Kazuki; Tachikawa, Naoki; Dokko, Kaoru; Watanabe, Masayoshi

New glyme-Li salt complexes were prepared by mixing equimolar amounts of a novel cyclic imide lithium salt LiN(C 2F 4S 2O 4) (LiCTFSI) and a glyme (triglyme (G3) or tetraglyme (G4)). The glyme-Li salt complexes, [Li(G3)][CTFSI] and [Li(G4)][CTFSI], are solid and liquid, respectively, at room temperature. The thermal stability of [Li(G4)][CTFSI] is much higher than that of pure G4, and the vapor pressure of [Li(G4)][CTFSI] is negligible at temperatures lower than 100 °C. Although the viscosity of [Li(G4)][CTFSI] is high (132.0 mPa s at 30 °C), because of its high molar concentration (ca. 3 mol dm -3), its ionic conductivity at 30 °C is relatively high, i.e., 0.8 mS cm -1, which is slightly lower than that of a conventional organic electrolyte solution (1 mol dm -3 LiTFSI dissolved in propylene carbonate). The self-diffusion coefficients of a Li + cation, a CTFSI - anion, and a glyme molecule were measured by the pulsed gradient spin-echo NMR method (PGSE-NMR). The ionicity (dissociativity) of [Li(G4)][CTFSI] at 30 °C is ca. 0.5, as estimated from the PGSE-NMR diffusivity measurements and the ionic conductivity measurements. Results of linear sweep voltammetry revealed that [Li(G4)][CTFSI] is electrochemically stable in an electrode potential range of 0-4.5 V vs. Li/Li +. The reversible deposition-stripping behavior of lithium was observed by cyclic voltammetry. The [LiCoO 2|[Li(G4)][CTFSI]|Li metal] cell showed a stable charge-discharge cycling behavior during 50 cycles, indicating that the [Li(G4)][CTFSI] complex is applicable to a 4 V class lithium secondary battery.

Lexical Complexity of Decision-Making Writing Tasks: Form-focused Guided Strategic Planning

Directory of Open Access Journals (Sweden)

Fatemeh Mahdavirad

2016-06-01

Full Text Available The present study is an attempt to investigate the effect of form-focused guided strategic planning on lexical complexity of learners’ performance in writing tasks. The twenty intermediate level participants of the study performed an unplanned and then a planned decision-making task. In the planned task condition, the participants were provided with form-focused guided strategic planning which contained detailed instructions about how to plan, by being instructed to focus on form. The guidance included an explanation of the necessary structural and lexical patterns employed to express the learners’ views while developing a comparison-and-contrast paragraph in each task. The results of the statistical analysis indicated that the participants produced a written product with a greater lexical complexity in their performance of the task in the form-focused strategic planning condition. The findings emphasize the importance of guided strategic planning as a task condition in syllabus design for task-based language teaching and the necessity of incorporating this task feature for accomplishing lexical complexity in decision-making writing tasks.

Rapid presumptive identification of the Mycobacterium tuberculosis-bovis complex by radiometric determination of heat stable urease

International Nuclear Information System (INIS)

Gandy, J.H.; Pruden, E.L.; Cox, F.R.

1983-01-01

Simple and rapid Bactec methodologies for the determination of neat (unaltered) and heat stable urease activity of mycobacteria are presented. Clinical isolates (63) and stock cultures (32)--consisting of: M. tuberculosis (19), M. bovis (5), M. kansasii (15), M. marinum (4), M. simiae (3), M. scrofulaceum (16), M. gordonae (6), M. szulgai (6), M. flavescens (1), M. gastri (1), M. intracellulare (6), M. fortuitum-chelonei complex (12), and M. smegmatis (1)--were tested for neat urease activity by Bactec radiometry. Mycobacterial isolates (50-100 mg wet weight) were incubated at 35 degrees C for 30 minutes with microCi14C-urea. Urease-positive mycobacteria gave Bactec growth index (GI) values greater than 100 units, whereas urease-negative species gave values less than 10 GI units. Eighty-three isolates possessing neat urease activity were heated at 80 degrees C for 30 minutes followed by incubation at 35 degrees C for 30 minutes with 1 microCi14C-urea. Mycobacterium tuberculosis-bovis complex demonstrated heat-stable urease activity (GI more than 130 units) and could be distinguished from mycobacteria other than tuberculosis (MOTT), which gave GI values equal to or less than 40 units

Broken Homes: Stable Risk, Changing Reasons, Changing Forms.

Science.gov (United States)

Sweetser, Dorrian Apple

1985-01-01

Cohort membership and two measures of social disadvantage were used as explanatory variables in analysis of the risk of growing up in a broken home and of the living arrangements of children with broken homes. The risk of a broken home by age 16 proved to be stable across cohorts and greater for those from disadvantaged homes. (Author/BL)

Stable tetrabenzo-Chichibabin's hydrocarbons: Tunable ground state and unusual transition between their closed-shell and open-shell resonance forms

KAUST Repository

Zeng, Zebing

2012-09-05

Stable open-shell polycyclic aromatic hydrocarbons (PAHs) are of fundamental interest due to their unique electronic, optical, and magnetic properties and promising applications in materials sciences. Chichibabin\\'s hydrocarbon as a classical open-shell PAH has been investigated for a long time. However, most of the studies are complicated by their inherent high reactivity. In this work, two new stable benzannulated Chichibabin\\'s hydrocarbons 1-CS and 2-OS were prepared, and their electronic structure and geometry in the ground state were studied by various experiments (steady-state and transient absorption spectra, NMR, electron spin resonance (ESR), superconducting quantum interference device (SQUID), FT Raman, X-ray crystallographic etc.) and density function theory (DFT) calculations. 1-CS and 2-OS exhibited tunable ground states, with a closed-shell quinoidal structure for 1-CS and an open-shell biradical form for 2-OS. Their corresponding excited-state forms 1-OS and 2-CS were also chemically approached and showed different decay processes. The biradical 1-OS displayed an unusually slow decay to the ground state (1-CS) due to a large energy barrier (95 ± 2.5 kJ/mol) arising from severe steric hindrance during the transition from an orthogonal biradical form to a butterfly-like quinoidal form. The quick transition from the quinoidal 2-CS (excited state) to the orthogonal biradicaloid 2-OS (ground state) happened during the attempted synthesis of 2-CS. Compounds 1-CS and 2-OS can be oxidized into stable dications by FeCl 3 and/or concentrated H 2SO 4. The open-shell 2-OS also exhibited a large two-photon absorption (TPA) cross section (760 GM at 1200 nm). © 2012 American Chemical Society.

X-ray fluorescence analysis of bimetallic complexes on the basis of tantalocene trihydride

International Nuclear Information System (INIS)

Shurupova, T.I.; Sokolova, T.A.

1989-01-01

Methods of X-ray fluorescence determination of metals in tantalocene trihydride complexes of Cp 2 TaH 3 ·nMeHalm composition where Me=Cu, Mg, Hal=Cl, I, n=1 or 2, m=1 or 2 are developed. To obtain the form, stable in relation to the air oxygen and water vapours, the complexes were burut off up to metal oxides. Possibility of direct X-ray fluorescent determination is tested taking the most stable iodide copper-containing complex as an example

Finding Non-Zero Stable Fixed Points of the Weighted Kuramoto model is NP-hard

OpenAIRE

Taylor, Richard

2015-01-01

The Kuramoto model when considered over the full space of phase angles [$0,2\\pi$) can have multiple stable fixed points which form basins of attraction in the solution space. In this paper we illustrate the fundamentally complex relationship between the network topology and the solution space by showing that determining the possibility of multiple stable fixed points from the network topology is NP-hard for the weighted Kuramoto Model. In the case of the unweighted model this problem is shown...

Inert and stable erbium(III)-cored complexes based on metalloporphyrins bearing aryl-ether dendron for optical amplification: synthesis and emission enhancement

International Nuclear Information System (INIS)

Oh, Jae Buem; Kim, Yong Hee; Nah, Min Kook; Kim, Hwan Kyu

2005-01-01

We have developed novel inert and stable erbium (Er)(III)-cored complexes based on metalloporphyrins for optical amplification. The functionalized metalloporphyrin ligands have been designed and synthesized to provide enough coordination sites for the formation of inert and stable 9-coordinated Er(III)-cored complexes. Er 3+ ions were encapsulated by the metalloporphyrin ligands, such as Zn(II)- and Pt(II)-porphyrins. The near-infrared (IR) emission intensity of Er 3+ ion is much stronger in the Er(III)-cored complex based on Pt(II)-porphyrin than Er(III)-cored complex based on Zn(II)-porphyrin. Furthermore, we have incorporated a G2-aryl-ether functionalized dendron into the Er(III)-cored complex, yielding an Er(III)-cored dendrimer complex bearing the Pt(II)-porphyrin. The Er(III)-cored dendrimer complex shows the stronger near-IR emission intensity than the corresponding complex based on Pt(II)-porphyrin by seven times in solid state. The lifetimes of the emission band of Pt(II)-porphyrin ligands in the visible region were found to be 30 and 40 μs for the Er(III)-cored complex and the Er(III)-cored dendrimer complex based on Pt(II)-porphyrin in deoxygenated THF solution samples, respectively. Also, in both cases, the sensitized luminescence intensity is increased in deoxygenated solution. Therefore, it indicates that the energy transfer from the metalloporphyrins to Er 3+ ions takes places through the triplet state. In this paper, the synthesis and photophysical properties of novel Er(III)-cored complexes based on metalloporphyrins and Er(III)-cored dendrimer complex based on metalloporphyrin will be discussed

Anion-π aromatic neutral tweezers complexes: are they stable in polar solvents?

Science.gov (United States)

Sánchez-Lozano, Marta; Otero, Nicolás; Hermida-Ramón, Jose M; Estévez, Carlos M; Mandado, Marcos

2011-03-17

The impact of the solvent environment on the stabilization of the complexes formed by fluorine (T-F) and cyanide (T-CN) substituted tweezers with halide anions has been investigated theoretically. The study was carried out using computational methodologies based on density functional theory (DFT) and symmetry adapted perturbation theory (SAPT). Interaction energies were obtained at the M05-2X/6-31+G* level. The obtained results show a large stability of the complexes in solvents with large dielectric constant and prove the suitability of these molecular tweezers as potential hosts for anion recognition in solution. A detailed analysis of the effects of the solvent on the electron withdrawing ability of the substituents and its influence on the complex stability has been performed. In particular, the interaction energy in solution was split up into intermonomer and solvent-complex terms. In turn, the intermonomer interaction energy was partitioned into electrostatic, exchange, and polarization terms. Polar resonance structures in T-CN complexes are favored by polar solvents, giving rise to a stabilization of the intermonomer interaction, the opposite is found for T-F complexes. The solvent-complex energy increases with the polarity of the solvent in T-CN complexes, nonetheless the energy reaches a maximum and then decreases slowly in T-F complexes. An electron density analysis was also performed before and after complexation, providing an explanation to the trends followed by the interaction energies and their different components in solution.

Structure of the active form of human origin recognition complex and its ATPase motor module

Energy Technology Data Exchange (ETDEWEB)

Tocilj, Ante; On, Kin Fan; Yuan, Zuanning; Sun, Jingchuan; Elkayam, Elad; Li, Huilin; Stillman, Bruce; Joshua-Tor, Leemor

2017-01-23

Binding of the Origin Recognition Complex (ORC) to origins of replication marks the first step in the initiation of replication of the genome in all eukaryotic cells. Here, we report the structure of the active form of human ORC determined by X-ray crystallography and cryo-electron microscopy. The complex is composed of an ORC1/4/5 motor module lobe in an organization reminiscent of the DNA polymerase clamp loader complexes. A second lobe contains the ORC2/3 subunits. The complex is organized as a double-layered shallow corkscrew, with the AAA+ and AAA+-like domains forming one layer, and the winged-helix domains (WHDs) forming a top layer. CDC6 fits easily between ORC1 and ORC2, completing the ring and the DNA-binding channel, forming an additional ATP hydrolysis site. Analysis of the ATPase activity of the complex provides a basis for understanding ORC activity as well as molecular defects observed in Meier-Gorlin Syndrome mutations.

Heavy stable isotopes of oxyanion-forming metals and metalloids (Cr, Se, U, Sb, and Te) as indicators of redox reactions: Theory, systematics, and the outlook for practical applications.

Science.gov (United States)

Johnson, T. M.

2016-12-01

The complex chemical behaviors of Cr, Se, U, Sb, and Te present challenges as we try to understand, predict, and/or manipulate their mobility, bioavailability, and toxicity in the environment. Redox reactions are particularly important and complex. In natural systems, aqueous concentrations and speciation can be used to infer the occurrence and rates of redox reactions, but are often of limited usefulness, for example when a reaction product is insoluble and its production is not readily observed in the field. Stable isotope ratio shifts in these elements can provide direct evidence for the occurrence of reduction, a critically important process that usually renders their soluble and mobile oxidized forms insoluble (or less soluble, in the case of Sb). Reduction kinetics differ between isotopes, and the remaining unreacted, oxidized contaminant becomes progressively shifted in its isotope ratio as reduction proceeds, providing a direct indicator of reduction in natural systems. Estimates of the extent of reduction are possible, but carry considerable uncertainty: The magnitude of isotopic fractionation induced by a reaction depends on the reaction mechanism and conditions, and thus prediction of fractionation factors for specific locations is uncertain. Furthermore, the simple Rayleigh distillation model is inaccurate due to complex reactive transport dynamics in aquifers and surface water systems. Nonetheless, useful estimates of reduction rates have been made and should be increasingly helpful as they are combined with other methods in environmental studies. Oxidation is less consistent in generating isotopic fractionation; this can be understood in terms of fundamental kinetic considerations. Furthermore, the reduced forms are usually solid and this further limits isotopic fractionation during oxidation. Sorption processes in some cases induce isotopic fractionation, but generally of smaller magnitude than reduction because bonding changes are relatively small

Ranking stability and super-stable nodes in complex networks.

Science.gov (United States)

Ghoshal, Gourab; Barabási, Albert-László

2011-07-19

Pagerank, a network-based diffusion algorithm, has emerged as the leading method to rank web content, ecological species and even scientists. Despite its wide use, it remains unknown how the structure of the network on which it operates affects its performance. Here we show that for random networks the ranking provided by pagerank is sensitive to perturbations in the network topology, making it unreliable for incomplete or noisy systems. In contrast, in scale-free networks we predict analytically the emergence of super-stable nodes whose ranking is exceptionally stable to perturbations. We calculate the dependence of the number of super-stable nodes on network characteristics and demonstrate their presence in real networks, in agreement with the analytical predictions. These results not only deepen our understanding of the interplay between network topology and dynamical processes but also have implications in all areas where ranking has a role, from science to marketing.

Increasing volume and complexity of pediatric epilepsy surgery with stable seizure outcome between 2008 and 2014

DEFF Research Database (Denmark)

Barba, Carmen; Specchio, Nicola; Guerrini, Renzo

2017-01-01

Objective The objective of the study was to assess common practice in pediatric epilepsy surgery in Italy between 2008 and 2014. Methods A survey was conducted among nine Italian epilepsy surgery centers to collect information on presurgical and postsurgical evaluation protocols, volumes and type...... and facilities. Significance This survey reveals an increase in volume and complexity of pediatric epilepsy surgery in Italy between 2008 and 2014, associated with a stable seizure outcome....

Chemistry of Stable Carbenes and «Green» Technologies

Directory of Open Access Journals (Sweden)

Korotkikh, N.I.

2015-11-01

Full Text Available Brief analysis of fundamental research in the chemistry of stable carbenes and applications in the field of «green» chemistry on their basis carried out at the L.M. Litvinenko Institute of Physical Organic & Coal Chemistry of NAS of Ukraine over the last decade is given. Carbene versions of ester Claisen condensation to form zwitterionic compounds, the Leuckart-Wallach reaction with the autoreduction of carbenoid azolium salts, Hofmann cleavage of aminocarbene insertion products, an induced tandem autotransformation of 1,2,4-triazol-5-ylidenes into 5-amidino-1,2,4-triazoles were found. New carbene reactions of ad dition, deesterification, oxidation and complexation were revealed. Effective methods of obtaining stable carbenes and carbenoids were suggested. New types of carbenes, namely benzimidazolylidenes, superstable conjugated biscarbenes and new types of carbenoids were synthesized. The existence of hypernucleophilic carbenes was theoretically predicted and experimentally confirmed. The prospects of the use of carbenes and their derivatives, in particular, carbene complexes of transition metals in catalysis of organic reactions and the search of biologically active compounds were shown.

Fractionation of Stable Isotopes in Atmospheric Aerosol Reactions

DEFF Research Database (Denmark)

Meusinger, Carl

-independent) fractionation processes of stable isotopes of C, N, O and S in order to investigate three different systems related to aerosols: 1. Post-depositional processes of nitrate in snow that obscure nitrate ice core records 2. Formation and aging of secondary organic aerosol generated by ozonolysis of X...... reactions and undergo complex chemical and physical changes during their lifetimes. In order to assess processes that form and alter aerosols, information provided by stable isotopes can be used to help constrain estimates on the strength of aerosol sources and sinks. This thesis studies (mass...... as required. The kndings provide important results for the studies' respective felds, including a description of the isotopic fractionation and quantum yield of nitrate photolysis in snow, equilibrium fractionation in secondary organic aerosol and fractionation constants of different oxidation pathways of SO2....

Polymorphic drugs examined with neutron spectroscopy: Is making more stable forms really that simple?

DEFF Research Database (Denmark)

Tsapatsaris, Nikolaos; Landsgesell, Sven; Koza, Michael Marek

2013-01-01

Understanding  polymorphism  in  pharmaceutical  ingredients  is  a   long-­  standing  challenge.  A  well-­known  example  is  paracetamol,  C8H9NO2.   The  marketed  stable  form  I  crystallizes  with  corrugated  molecular  layers.   In  contrast,  form  II,  which  is  thermodynamically......  favorable  at  high   pressures,  has  relatively  planar  layers  that  can  slip  over  each  other   without  difficulty,    is  metastable  at  ambient  conditions.  By  means  of   inelastic  neutron  scattering  we  demonstrated  that  the  lattice  modes  of   form  II  exhibit  a  sudden  1  me......V  energy  shift  at  300  K  under  a  pressure  of   ca  0.4  GPa.  Moreover,  evidence  of  an  increase  of  the  vibrational  energy   in  both  polymorphs  was  found,  which  was  accompanied,  in  form  I,  by  an   unexpectedly  weak  increase  of  the  tunnel  splitting.  These  results   indicate...

Preparation, Characterization and Thermal Properties of Paraffin Wax – Expanded Perlite Form-Stable Composites for Latent Heat Storage

Directory of Open Access Journals (Sweden)

Tugba GURMEN OZCELIK

2017-02-01

Full Text Available In this study, form-stable composite phase change materials (PCM for latent heat storage were prepared by impregnating paraffin wax into the pores of the expanded perlite (EP. The characterization of the composite PCMs was performed by FTIR, TGA, SEM and DSC analysis. The melting point and heat of fusion were determined for 25 % paraffin included composite, as 54.3 °C and 94.71 J/g and for 45 % paraffin included composite as 53.6 °C and 106.69 J/g, respectively. The FTIR results showed that there were no chemical reaction between the perlite and paraffin. TGA analysis indicated that both composite PCMs had good thermal stability. SEM images showed that the paraffin was dispersed uniformly into the pores and on the EP surface. There was no leakage and degradation at the composite PCMs after heating and cooling cycles. According to the results, both prepared composites showed good thermal energy storage properties, reliability and stability. All results suggested that the presented form- stable composite PCMs has great potential for thermal energy storage applications.DOI: http://dx.doi.org/10.5755/j01.ms.23.1.13661

Split degenerate states and stable p+ip phases from holography

Energy Technology Data Exchange (ETDEWEB)

Nie, Zhang-Yu; Zeng, Hui [Kunming University of Science and Technology, Kunming (China); Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing (China); Pan, Qiyuan [Hunan Normal Univ., Key Lab. of Low Dimensional Quantum Structures and Quantum Control of Ministry of Education, and Synergetic Innovation Center for Quantum Effects and Applications, Dept. of Physics, Changsha (China); Zeng, Hua-Bi [Yangzhou University, College of Physics Science and Technology, Yangzhou, Jiangsu (China); National Central University, Department of Physics, Chungli (China)

2017-02-15

In this paper, we investigate the p+ip superfluid phases in the complex vector field holographic p-wave model. We find that in the probe limit, the p+ip phase and the p-wave phase are equally stable, hence the p and ip orders can be mixed with an arbitrary ratio to form more general p+λip phases, which are also equally stable with the p-wave and p+ip phases. As a result, the system possesses a degenerate thermal state in the superfluid region. We further study the case on considering the back-reaction on the metric, and we find that the degenerate ground states will be separated into p-wave and p+ip phases, and the p-wave phase is more stable. Finally, due to the different critical temperature of the zeroth order phase transitions from p-wave and p+ip phases to the normal phase, there is a temperature region where the p+ip phase exists but the p-wave phase does not. In this region we find the stable holographic p+ip phase for the first time. (orig.)

What can Fe stable isotopes tell us about magmas?

DEFF Research Database (Denmark)

Stausberg, Niklas

the differentiation of magmas from the perspective of Fe stable isotopes, integrated with petrology, by studying igneous rocks and their constituent phases (minerals and glasses) from the Bushveld Complex, South Africa, Thingmuli, Iceland, Pantelleria, Italy, and the Bishop Tuff, USA. The findings are interpreted......The majority of the Earth’s crust is formed by magmas, and understanding their production and differentiation is important to interpret the geologic rock record. A powerful tool to investigate magmatic processes is the distribution of the stable isotopes of the major redox-sensitive element...... in magmas, Fe. Fe isotope compositions of magmatic rocks exhibit systematic differences, where the heaviest compositions are found in rhyolites and granites. Understanding of these systematics is complicated by a lack of constraints on Fe isotope fractionation among minerals and liquids under magmatic...

Synchronization of complex chaotic systems in series expansion form

International Nuclear Information System (INIS)

Ge Zhengming; Yang Chenghsiung

2007-01-01

This paper studies the synchronization of complex chaotic systems in series expansion form by Lyapunov asymptotical stability theorem. A sufficient condition is given for the asymptotical stability of an error dynamics, and is applied to guiding the design of the secure communication. Finally, numerical results are studied for the Quantum-CNN oscillators synchronizing with unidirectional/bidirectional linear coupling to show the effectiveness of the proposed synchronization strategy

Structure of stable degeneration of K3 surfaces into pairs of rational elliptic surfaces

Science.gov (United States)

Kimura, Yusuke

2018-03-01

F-theory/heterotic duality is formulated in the stable degeneration limit of a K3 fibration on the F-theory side. In this note, we analyze the structure of the stable degeneration limit. We discuss whether stable degeneration exists for pairs of rational elliptic surfaces. We demonstrate that, when two rational elliptic surfaces have an identical complex structure, stable degeneration always exists. We provide an equation that systematically describes the stable degeneration of a K3 surface into a pair of isomorphic rational elliptic surfaces. When two rational elliptic surfaces have different complex structures, whether their sum glued along a smooth fiber admits deformation to a K3 surface can be determined by studying the structure of the K3 lattice. We investigate the lattice theoretic condition to determine whether a deformation to a K3 surface exists for pairs of extremal rational elliptic surfaces. In addition, we discuss the configurations of singular fibers under stable degeneration. The sum of two isomorphic rational elliptic surfaces glued together admits a deformation to a K3 surface, the singular fibers of which are twice that of the rational elliptic surface. For special situations, singular fibers of the resulting K3 surface collide and they are enhanced to a fiber of another type. Some K3 surfaces become attractive in these situations. We determine the complex structures and the Weierstrass forms of these attractive K3 surfaces. We also deduce the gauge groups in F-theory compactifications on these attractive K3 surfaces times a K3. E 6, E 7, E 8, SU(5), and SO(10) gauge groups arise in these compactifications.

High-field/ high-frequency EPR study on stable free radicals formed in sucrose by gamma-irradiation.

Science.gov (United States)

Georgieva, Elka R; Pardi, Luca; Jeschke, Gunnar; Gatteschi, Dante; Sorace, Lorenzo; Yordanov, Nicola D

2006-06-01

The EPR spectrum of sucrose irradiated by high-energy radiation is complex due to the presence of more than one radical species. In order to decompose the spectrum and elucidate the radical magnetic parameters a high-field (HF(-)EPR) study on stable free radicals in gamma-irradiated polycrystalline sucrose (table sugar) was performed at three different high frequencies--94, 190 and 285 GHz as well as at the conventional X-band. We suggest a presence of three stable radicals R1, R2 and R3 as the main radical species. Due to the increase of g-factor resolution at high fields the g-tensors of these radicals could be extracted by accurate simulations. The moderate g-anisotropy suggests that all three radicals are carbon-centred. Results from an earlier ENDOR study on X-irradiated sucrose single crystals (Vanhaelewyn et al., Appl Radiat Isot, 52, 1221 (2000)) were used for analyzing of the spectra in more details. It was confirmed that the strongest hyperfine interaction has a relatively small anisotropy, which indicates either the absence of alpha-protons or a strongly distorted geometry of the radicals.

Elaboration of Stable and Antibody Functionalized Positively Charged Colloids by Polyelectrolyte Complexation between Chitosan and Hyaluronic Acid

Directory of Open Access Journals (Sweden)

Ramona C. Polexe

2013-07-01

Full Text Available In this study, we describe the elaboration of multifunctional positively charged polyelectrolyte complex (PEC nanoparticles, designed to be stable at physiological salt concentration and pH, for effective targeted delivery. These nanoparticles were obtained by charge neutralization between chitosan (CS as polycation and hyaluronic acid (HA as polyanion. We showed that the course of the complexation process and the physico-chemical properties of the resulting colloids were impacted by (i internal parameters such as the Degree of Acetylation (DA, i.e., the molar ration of acetyl glucosamine residues and molar mass of CS, the HA molar mass and (ii external parameters like the charge mixing ratio and the polymer concentrations. As a result, nonstoichiometric colloidal PECs were obtained in water or PBS (pH 7.4 and remained stable over one month. The polymer interactions were characterized by thermal analysis (DSC and TGA and the morphology was studied by scanning electron microscopy. A model antibody, anti-ovalbumine (OVA immunoglobulin A (IgA was sorbed on the particle surface in water and PBS quantitatively in 4 h. The CS-HA/IgA nanoparticles average size was between 425–665 nm with a positive zeta potential. These results pointed out that CS-HA can be effective carriers for use in targeted drug delivery.

Lexical Complexity of Decision-Making Writing Tasks: Form-focused Guided Strategic Planning

OpenAIRE

Mahdavirad, Fatemeh

2016-01-01

The present study is an attempt to investigate the effect of form-focused guided strategic planning on lexical complexity of learners’ performance in writing tasks. The twenty intermediate level participants of the study performed an unplanned and then a planned decision-making task. In the planned task condition, the participants were provided with form-focused guided strategic planning which contained detailed instructions about how to plan, by being instructed to focus on form. The guidanc...

Spectroscopic study of divalent copper complexes forming in the systems CuCl2-MCl (M= Na, K, Rb, Cs)

International Nuclear Information System (INIS)

Utorov, N.P.; Bakshi, Yu.M.; Bazov, V.P.; Gel'bshtejn, A.I.

1982-01-01

The structure of complex ions formed in salt systems CuCl 2 -MCl depending on the nature of cation of alkali metal chloride at different mole ratios (n=MCl/CuCl 2 ) is studied. The data obtained using the methods of oscillation and electron spectroscopy enable to consider that during the melting of CuCl 2 and CsCl at n 4 2- ions, have the symmetry Csub(2v) at n=1. π-bonding, which is realized with participation of of Cl - p-orbitals and Cu 2+ d-orbitals plays a very important role in the formation of dimers and polymer chains. π-conjugated systems are characterized by the spectrum of charge transfer in the visible region. Charge transfer promotes metal reduction in the excited state which is adequate to the change of electron configuration of copper from d 9 for d 10 . It results in the decrease of acceptor and increase of dative ability of copper cation in the composition of salt complex. Big (n >= 2) additions of CsCl lead to the formation of separate stable ions of CuCl 4 2- type with the symmetry Dsub(2d)

Characterization of polymethyl methacrylate/polyethylene glycol/aluminum nitride composite as form-stable phase change material prepared by in situ polymerization method

International Nuclear Information System (INIS)

Zhang, Lei; Zhu, Jiaoqun; Zhou, Weibin; Wang, Jun; Wang, Yan

2011-01-01

Highlights: → Form-stable PMMA/PEG/AlN PCMs were prepared by in situ polymerization method. → AlN additive effectively enhanced the heat transfer property of composite PCMs. → The composites exhibited desirable thermal performance and electric insulativity. → The composites were available for the thermal management of electronic device. - Abstract: This work was focused on the preparation and characterization of a new type of form-stable phase change material (PCM) employed in thermal management. Using the method of in situ polymerization, polyethylene glycol (PEG) acting as the PCM and aluminum nitride (AlN) serving as the thermal conductivity promoter were uniformly encapsulated and embedded inside the three-dimensional network structure of PMMA matrix. When the mass fraction of PEG was below 70%, the prepared composite PCMs remained solid without leakage above the melting point of the PEG. XRD and FT-IR results indicated that the PEG was physically combined with PMMA matrix and AlN additive and did not participate in the polymerization. Thermal analysis results showed that the prepared composite PCMs possess available latent heat capacity and thermal stability, and the AlN additive was able to effectively enhance the heat transfer property of organic PCM. Moreover, the volume resistivity of composite achieved (5.92 ± 0.16) x 10 10 Ω cm when the mass ratio of AlN was 30%. To sum up, the prepared form-stable PCMs were competent for the thermal management of electronic device due to their acceptable thermal performance and electric insulativity.

Computation of 3D form factors in complex environments

International Nuclear Information System (INIS)

Coulon, N.

1989-01-01

The calculation of radiant interchange among opaque surfaces in a complex environment poses the general problem of determining the visible and hidden parts of the environment. In many thermal engineering applications, surfaces are separated by radiatively non-participating media and may be idealized as diffuse emitters and reflectors. Consenquently the net radiant energy fluxes are intimately related to purely geometrical quantities called form factors, that take into account hidden parts: the problem is reduced to the form factor evaluation. This paper presents the method developed for the computation of 3D form factors in the finite-element module of the system TRIO, which is a general computer code for thermal and fluid flow analysis. The method is derived from an algorithm devised for synthetic image generation. A comparison is performed with the standard contour integration method also implemented and suited to convex geometries. Several illustrative examples of finite-element thermal calculations in radiating enclosures are given

Quasi-stable injection channels in a wakefield accelerator

CERN Document Server

Wiltshire-Turkay, Mara; Pukhov, Alexander

2016-01-01

Particle-driven plasma-wakefield acceleration is a promising alternative to conventional electron acceleration techniques, potentially allowing electron acceleration to energies orders of magnitude higher than can currently be achieved. In this work we investigate the dependence of the energy gain on the position at which electrons are injected into the wake. Test particle simulations show previously unobserved complex structure in the parameter space, with quasi-stable injection channels forming for particles injected in narrow regions away from the centre of the wake. The result is relevant to the planning and tuning of experiments making use of external injection.

Interpolymer complexation: comparisons of bulk and interfacial structures.

Science.gov (United States)

Cattoz, Beatrice; de Vos, Wiebe M; Cosgrove, Terence; Crossman, Martin; Espidel, Youssef; Prescott, Stuart W

2015-04-14

The interactions between the strong polyelectrolyte sodium poly(styrenesulfonate), NaPSS, and the neutral polymer poly(vinylpyrrolidone), PVP, were investigated in bulk and at the silica/solution interface using a combination of diffusion nuclear magnetic resonance spectroscopy (NMR), small-angle neutron scattering (SANS), solvent relaxation NMR, and ellipsometry. We show for the first time that complex formation occurs between NaPSS and PVP in solution; the complexes formed were shown not to be influenced by pH variation, whereas increasing the ionic strength increases the complexation of NaPSS but does not influence the PVP directly. The complexes formed contained a large proportion of NaPSS. Study of these interactions at the silica interface demonstrated that complexes also form at the nanoparticle interface where PVP is added in the system prior to NaPSS. For a constant PVP concentration and varying NaPSS concentration, the system remains stable until NaPSS is added in excess, which leads to depletion flocculation. Surface complex formation using the layer-by-layer technique was also reported at a planar silica interface.

Development of form stable Poly(methyl methacrylate) (PMMA) coated thermal phase change material for solar water heater applications

Science.gov (United States)

Munusamy, Y.; Shanmugam, S.; Shi-Ying, Kee

2018-04-01

Phase change material (PCM) is one of the most popular and widely used thermal energy storage material in solar water heater because it able to absorb and release a large amount of latent heat during a phase change process over a narrow temperature range. However the practical application of PCM is limited by two major issues; 1) leakage which leads to material loss and corrosion of tank and 2) large volume change during phase change process which cause pressure build up in the tank. In this work, form-stable PCM was prepared by coating myristic acid with Poly(methyl methacrylate) (PMMA) to prevent leakage of PCM. PMMA was mixed with different weight percentage (0.1, 0.2, 0.3, 0.4 and 0.5 wt%) of dicumyl peroxide (DCP). The purpose of adding DCP to PMMA is to crosslink the polymer and to increase the mechanical strength of PMMA to hold the myristic acid content inside the coating during the phase change process. Leakage test results showed that PMMA mixed with 0.1% DCP exhibit 0% leakage. This result is further supported by Field Emission Scanning Electron Microscopy (FESEM) images and Fourier transform infrared spectroscopy (FTIR) analysis results, where a compact and uniform coating without cracks were formed for PCM coated with PMMA with 0.1% DCP. Differential scanning calorimetry (DSC) results shows that the melting point of form-stable PCM is 55°C, freezing point is 50°C, the latent heat of melting and freezing is 67.59 J/g.

Study on polyethylene glycol/epoxy resin composite as a form-stable phase change material

International Nuclear Information System (INIS)

Fang Yutang; Kang Huiying; Wang Weilong; Liu Hong; Gao Xuenong

2010-01-01

Form-stable polyethylene glycol (PEG)/epoxy resin (EP) composite as a novel phase change material (PCM) was prepared using casting molding method. In this new material, PEG acts as the latent heat storage material and EP polymer serves as the supporting material, which provides structural strength and prevents the leakage of the melted PEG. The structure and morphology of the novel composite were observed using Fourier transformation infrared spectroscope (FTIR) and scanning electronic microscope (SEM). The thermo-mechanical property and transition behavior were characterized by polarizing optical microscope (POM), static thermo-mechanical analysis (TMA) and differential scanning calorimeter (DSC). The experimental results show that, as a result of the physical tangled function of the epoxy resin carrier to the PEG segment, the composite macroscopically presents the solid-solid phase change characteristic.

Correlation between microstructure and mechanical properties of stable mixtures formed by austenite and martensite

International Nuclear Information System (INIS)

Eckstein, C.B.

1982-03-01

The influence of martensite in mechanical properties of stable mixtures formed by austenite and martensite was studied by varying the amount of martensite in the mixtures. Microstructural parameters were determined by Optical Quantitative Metallography and used to establish the correlation between the mechanical response of the mixtures in tension and their microstructures. The 'in situ' deformation of each phase in mixtures was determined experimentally in terms of the rule of mixtures. It is shown that the partitioning of the deformation depends on the amount of martensite in the mixture and that it tends to a condition of isostrain at higher martensite volume fractions. Optical observation of fractured specimens showed that the beginning of the fracture process may related to regions of the austenite grain boundaries where they meet martensite plates. (Author) [pt

Rubber pad forming - Efficient approach for the manufacturing of complex structured sheet metal blanks for food industry

Science.gov (United States)

Spoelstra, Paul; Djakow, Eugen; Homberg, Werner

2017-10-01

The production of complex organic shapes in sheet metals is gaining more importance in the food industry due to increasing functional and hygienic demands. Hence it is necessary to produce parts with complex geometries promoting cleanability and general sanitation leading to improvement of food safety. In this context, and especially when stainless steel has to be formed into highly complex geometries while maintaining desired surface properties, it is inevitable that alternative manufacturing processes will need to be used which meet these requirements. Rubber pad forming offers high potential when it comes to shaping complex parts with excellent surface quality, with virtually no tool marks and scratches. Especially in cases where only small series are to be produced, rubber pad forming processes offers both technological and economic advantages. Due to the flexible punch, variation in metal thickness can be used with the same forming tool. The investments to set-up Rubber pad forming is low in comparison to conventional sheet metal forming processes. The process facilitates production of shallow sheet metal parts with complex contours and bends. Different bending sequences in a multiple tool set-up can also be conducted. The planned contribution thus describes a brief overview of the rubber pad technology. It shows the prototype rubber pad forming machine which can be used to perform complex part geometries made from stainless steel (1.4301). Based on an analysis of the already existing systems and new machines for rubber pad forming processes, together with their process properties, influencing variables and areas of application, some relevant parts for the food industry are presented.

NMR studies of inclusion complexes formed by (R)-α-lipoic acid with α-, β-, and γ-cyclodextrins

International Nuclear Information System (INIS)

Ikeda, Hiroshi; Ikuta, Naoko; Nakata, Daisuke; Ishida, Yoshiyuki; Terao, Keiji

2015-01-01

The structures of inclusion complexes of (R)-α-lipoic acid with α-, β-, and γ-cyclodextrin (CD) were constructed using restraints derived from ROESY spectra and MMFF94 molecular mechanics calculations. (R)-α-lipoic acid and α-CD generate a single stable inclusion complex, in which the 1,2-dithiolane ring of the (R)-α-lipoic acid is oriented toward the secondary hydroxy side of the α-CD. NMR data suggests that β-CD produces two kinds of inclusion complexes with α-lipoic acid. Finally, γ-CD yields 1:1 and 1:2 host/guest complexes with (R)-α-lipoic acid. The estimated structure of the 1:1 γ-CD inclusion complex has the 1,2-dithiolane ring oriented toward the primary hydroxy side of the γ-CD. (author)

Measurement of the bio-availability in man of a pharmaceutic form of magnesium, by the means of stable isotopes

International Nuclear Information System (INIS)

Benech, H.; Pruvost, A.; Grognet, J.M.; Morge, X.

1994-01-01

A method for measuring the absolute bio-availability, in man, of an oral magnesium pharmaceutic form by the means of the simultaneous utilization of two stable magnesium isotopes, 25 Mg and 26 Mg, by oral or intra-venous administrations in order to study the metabolism of magnesium in the human body, is presented. Fecal elimination and urinary excretion of magnesium are recorded. 10 refs

Formation of stable nanoparticles via electrostatic complexation between sodium caseinate and gum arabic.

Science.gov (United States)

Ye, Aiqian; Flanagan, John; Singh, Harjinder

2006-06-05

The formation of electrostatic complexes between sodium caseinate and gum arabic (GA) was studied as a function of pH (2.0-7.0), using slow acidification in situ with glucono-delta-lactone (GDL) or titration with HCl. The colloidal behavior of the complexes under specific conditions was investigated using absorbance measurements (at 515 or 810 nm) and dynamic light scattering (DLS). In contrast to the sudden increase in absorbance and subsequent precipitation of sodium caseinate solutions at pH sodium caseinate and GA increased to a level that was dependent on GA concentration at pH 5.4 (pH(c)). The absorbance values remained constant with further decreases in pH until a sudden increase in absorbance was observed (at pH(phi)). The pH(phi) was also dependent upon the GA concentration. Dynamic light scattering (DLS) data showed that the sizes of the particles formed by the complexation of sodium caseinate and GA between pH(c) and pH(phi) were between 100 and 150 nm and these nanoparticles were visualized using negative staining transmission electron microscopy (TEM). Below pH(phi), the nanoparticles associated to form larger particles, causing phase separation. zeta-Potential measurements of the nanoparticles and chemical analysis after phase separation showed that phase separation was a consequence of charge neutralization. The formation of complexes between sodium caseinate and GA was inhibited at high ionic strength (>50 mM NaCl). It is postulated that the structure of the nanoparticles comprises an aggregated caseinate core, protected from further aggregation by steric repulsion of one, or more, electrostatically attached GA molecules. Copyright 2005 Wiley Periodicals, Inc.

A complex of meteorite-forming bodies (the Innisfree - Ridgedale family).

Science.gov (United States)

Shestaka, I. S.

1994-12-01

For the first time a swarm of meteorite-forming bodies was identified. Yearly this swarm's orbit approaches the Earth's orbit in early February. This swarm contains the Innisfree and Ridgedale fireballs, 9 small meteoric swarms, several asteroids and 12 fireballs photographed by the cameras of the Prairie Network and Canadian Meteorite Observation and Discovery Project. The discovery of this complex, intensive bombardments of the Moon's surface recorded by means of seismographs left on the Moon, the analysis of the time distributions of meteorite falls on the Earth and other established facts confirm the existence of swarms of meteorite-forming bodies which are crossing the Earth's orbit.

Mixed complexes formed by rare earths with nitrilotriacetic and malic acids

International Nuclear Information System (INIS)

Samir Abu Ali; Dobrynina, N.A.; Martynenko, L.I.; Borisova, L.I.

1980-01-01

The composition of the mixed ligand and homogeneous complexes, forming in the Ln 3+ system-nitrilotriacetic acid (H 3 X)-malic acid (H 2 Mal) is determined and stability constants are calculated according to the data of the spectrography and pH-metry with the help of the mathematical statistics. The LnHMal 2+ , LnX 0 , LnX 2 - 3 and LnXMal 2- complexes are found in the solutions with the LnCl 3 : H 3 X : H 2 Mal= 1 : 1 : 1 and 1 : 1 : 2 composition

Competition of hydrogen bonds and halogen bonds in complexes of hypohalous acids with nitrogenated bases.

Science.gov (United States)

Alkorta, Ibon; Blanco, Fernando; Solimannejad, Mohammad; Elguero, Jose

2008-10-30

A theoretical study of the complexes formed by hypohalous acids (HOX, X = F, Cl, Br, I, and At) with three nitrogenated bases (NH 3, N 2, and NCH) has been carried out by means of ab initio methods, up to MP2/aug-cc-pVTZ computational method. In general, two minima complexes are found, one with an OH...N hydrogen bond and the other one with a X...N halogen bond. While the first one is more stable for the smallest halogen derivatives, the two complexes present similar stabilities for the iodine case and the halogen-bonded structure is the most stable one for the hypoastatous acid complexes.

Forms of iron in soils on basement complex rocks of Kaduna state in ...

African Journals Online (AJOL)

The forms of iron extracted by different methods were studied in soils developed on four basement complex rocks within Northern Guinea Savanna of Nigeria namely: migmatite gneisses, older granite, quartzites and mica schists. The study shows that forms of iron generally decreased in the order of total elemental iron ...

Mixed-ligand complexes of dioxouranium(VI)

International Nuclear Information System (INIS)

Ahuja, Renu; Dwivedi, K.

1995-01-01

A number of mixed ligand complexes of UO 2 2+ ion have been studied with aminopolycarboxylic acids, such as ethylenediaminetetraacetic acid with coordination number (CN) = 6, nitrilotriacetic acid with CN = 4 and iminodiacetic acid with CN = 3. Ethyleneglycol-bis-2-aminoethylether tetraacetic acid (EGTA) is an octadentate aminopolycarboxylic acid and forms stable binary complexes with many metal ions at low pH. In this paper the results obtained for the study of 1:1:1 UO 2 VI -EGTA-aspartic acid/glutamic acid systems are studied. (author). 7 refs., 1 fig., 1 tab

A stable isotope approach for source apportionment of chlorinated ethene plumes at a complex multi-contamination events urban site

Science.gov (United States)

Nijenhuis, Ivonne; Schmidt, Marie; Pellegatti, Eleonora; Paramatti, Enrico; Richnow, Hans Hermann; Gargini, Alessandro

2013-10-01

The stable carbon isotope composition of chlorinated aliphatic compounds such as chlorinated methanes, ethanes and ethenes was examined as an intrinsic fingerprint for apportionment of sources. A complex field site located in Ferrara (Italy), with more than 50 years history of use of chlorinated aliphatic compounds, was investigated in order to assess contamination sources. Several contamination plumes were found in a complex alluvial sandy multi-aquifer system close to the river Po; sources are represented by uncontained former industrial and municipal dump sites as well as by spills at industrial areas. The carbon stable isotope signature allowed distinguishing 2 major sources of contaminants. One source of chlorinated aliphatic contaminants was strongly depleted in 13C (-40‰ which is commonly observed in recent production of chlorinated solvents. The degradation processes in the plumes could be traced interpreting the isotope enrichment and depletion of parent and daughter compounds, respectively. We demonstrate that, under specific production conditions, namely when highly chlorinated ethenes are produced as by-product during chloromethanes production, 13C depleted fingerprinting of contaminants can be obtained and this can be used to track sources and address the responsible party of the pollution in urban areas.

Dual hydrogen-bonding motifs in complexes formed between tropolone and formic acid

Science.gov (United States)

Nemchick, Deacon J.; Cohen, Michael K.; Vaccaro, Patrick H.

2016-11-01

The near-ultraviolet π*←π absorption system of weakly bound complexes formed between tropolone (TrOH) and formic acid (FA) under cryogenic free-jet expansion conditions has been interrogated by exploiting a variety of fluorescence-based laser-spectroscopic probes, with synergistic quantum-chemical calculations built upon diverse model chemistries being enlisted to unravel the structural and dynamical properties of the pertinent ground [X˜ 1A'] and excited [A˜ 1A'(" separators="π*π )] electronic states. For binary TrOH ṡ FA adducts, the presence of dual hydrogen-bond linkages gives rise to three low-lying isomers designated (in relative energy order) as INT, EXT1, and EXT2 depending on whether docking of the FA ligand to the TrOH substrate takes place internal or external to the five-membered reaction cleft of tropolone. While the symmetric double-minimum topography predicted for the INT potential surface mediates an intermolecular double proton-transfer event, the EXT1 and EXT2 structures are interconverted by an asymmetric single proton-transfer process that is TrOH-centric in nature. The A ˜ -X ˜ origin of TrOH ṡ FA at ν˜ 00=27 484 .45 cm-1 is displaced by δ ν˜ 00=+466 .76 cm-1 with respect to the analogous feature for bare tropolone and displays a hybrid type - a/b rotational contour that reflects the configuration of binding. A comprehensive analysis of vibrational landscapes supported by the optically connected X˜ 1A' and A˜ 1A'(" separators="π*π ) manifolds, including the characteristic isotopic shifts incurred by partial deuteration of the labile TrOH and FA protons, has been performed leading to the uniform assignment of numerous intermolecular (viz., modulating hydrogen-bond linkages) and intramolecular (viz., localized on monomer subunits) degrees of freedom. The holistic interpretation of all experimental and computational findings affords compelling evidence that an external-binding motif (attributed to EXT1), rather than the

Properties of aqueous dispersion of chitosan and chondroitin sulfate complex derived from aquatic organisms

Directory of Open Access Journals (Sweden)

Novikov V. Yu.

2016-09-01

Full Text Available Investigation of production of chondroitin sulfate, chitosan and polyelectrolyte complexes based on them received from the local marine raw materials is relevant from the point of view of developing a comprehensive waste-free technology for natural raw materials processing. The objects of study are chitosan derived from the shell of the Kamchatka crab Paralithodes camtschaticus and chondroitin sulfate derived from cartilage of salmon Salmon salar. To determine the surface tension of polyelectrolyte complex solutions and dispersions the Wilhelmy method has been used, the effective radius of particle dispersion has been calculated by light scattering, measurements of effective viscosity have been carried out under shear deformation. The conditions of formation, surface and rheological properties of the chitosan and chondroitin sulfate complex extracted from aquatic organisms in the Barents Sea have been studied. Obtaining conditions and molar ratios of these polyelectrolytes in which the aqueous dispersion of the complex remains stable for a long time have been established. It has been found that by addition of chondroitin sulfate solution to chitosan solution in molar ratios of 1 : 3; 1 : 6 the dispersion of the polyelectrolyte complex stable for 2 to 3 days has been formed. The polyelectrolyte complex dispersions behave as non-Newtonian pseudoplastic liquid. When the molar ratio of the mixed solution is 1 : 1 (regardless of the sequence of mixing suspension of the polyelectrolyte complex has been formed, then there is precipitation. Equilibrium surface tension of the aqueous dispersion of the polyelectrolyte complex is higher than that of solutions of chondroitin sulfate and chitosan. The effective radius of particles in the complex dispersion has been determined. The effective radius of the particles in the complex dispersion depends on the molar ratio of chondroitin sulfate : chitosan. A qualitative scheme of formation of polyelectrolyte

Interactions of trivalent and tetravalent heavy metal-siderophore complexes with pseudomonas fluorescens

International Nuclear Information System (INIS)

Yoshida, T.; Ozaki, T.; Ohnuki, T.; Francis, A.J.

2004-01-01

We investigated the interactions of the Fe(III)-, Eu(III)-, and Hf(IV)-desferrioxamine B (DFO) complexes with the Gram-negative aerobic bacterium Pseudomonas fluorescens. Potentiometric titration of 1:1 Fe(III)-, Eu(III)-, and Hf(IV)-DFO complexes showed that Hf(IV) formed a strong complex with DFO whose stability was comparable to that of the Fe(III)-DFO complex, while Eu(III) formed a weaker one. DFO in a growth medium was not degraded by P. fluorescens. Contact of P. fluorescens cells with the Fe(III)-, Eu(III)-, and Hf(IV)-DFO complexes at pH 4-9 revealed that there was negligible adsorption of Hf(IV) and Fe(III), whereas Eu(III) was dissociated from DFO and was readily adsorbed by the cells. These results suggest that Fe(III) and Hf(IV) form stable complexes with DFO and are not adsorbed by P. fluorescens cells. Europium(III) forms a weaker complex with DFO than Fe(III) and Hf(IV) do and its DFO complex is readily dissociated in the presence of the cells. (orig.)

Investigation into complexing of pentavalent actinide forms with some anions of organic acids by the coprecipitation method

International Nuclear Information System (INIS)

Moskvin, A.I.; Poznyakov, A.N.; AN SSSR, Moscow. Inst. Geokhimii i Analiticheskoj Khimii)

1979-01-01

Complexing of pentavolent forms of Np, Pu, Am actinides with anions of acetic, oxalic acids and EDTA is studied using the method of coprecipitation with iron hydroxide. Composition and stability constants of the actinide complexes formed are determined. The acids anions are arranged in a row in the order of decrease of complexing tendency that is EDTA anion>C 2 O 4 2- >CH 3 COO -

The chemical fate of 212Bi-DOTA formed by β- decay of 212Pb(DOTA)2-

International Nuclear Information System (INIS)

Mirzadeh, S.; Kumar, K.; Gansow, O.A.

1993-01-01

The increasing use of inert metal complexes in radioimmunotherapy prompted us to explore the potential use of 212 Pb chelates. Herein, we report a study of the chemical fate of the 212 Bi-DOTA complex formed by β - decay of 212 Pb(DOTA) 2- (H 4 DOTA = 1,4,7,10-tetraazacyclododecanetetraacetic acid). To assure that both parent and daughter complexes were thermally stable, kinetic studies were performed with 203 Pb(II) and 206 Bi(III) which showed that both lead and bismuth complexes with DOTA undergo chemical exchange only very slowly in aqueous solution at pH 4-10. To investigate whether the complex ion which results from decay of 212 Pb(DOTA) 2- was intact and also stable, solutions initially containing only this ion were analyzed for amounts of DOTA-complexed and uncomplexed 212 Bi after attaining transient equilibrium with 212 Bi. The fraction of 212 Bi radioactivity not complexed to DOTA, vide infra, was found to be 36±2%. This value represents the fraction of breakup of 212 Bi(DOTA) - formed from β - decay of the parent complex. By considering the various extranuclear processes responsible for kinetic and electronic excitation of the 212 Bi daughter, break-up of the 212 Bi-DOTA complex is ascribed to the internal conversion of γ-rays emitted by the excited 212 Bi nuclide. (orig.)

Biochemical principles underlying the stable maintenance of LTP by the CaMKII/NMDAR complex.

Science.gov (United States)

Lisman, John; Raghavachari, Sridhar

2015-09-24

Memory involves the storage of information at synapses by an LTP-like process. This information storage is synapse specific and can endure for years despite the turnover of all synaptic proteins. There must, therefore, be special principles that underlie the stability of LTP. Recent experimental results suggest that LTP is maintained by the complex of CaMKII with the NMDAR. Here we consider the specifics of the CaMKII/NMDAR molecular switch, with the goal of understanding the biochemical principles that underlie stable information storage by synapses. Consideration of a variety of experimental results suggests that multiple principles are involved. One switch requirement is to prevent spontaneous transitions from the off to the on state. The highly cooperative nature of CaMKII autophosphorylation by Ca(2+) (Hill coefficient of 8) and the fact that formation of the CaMKII/NMDAR complex requires release of CaMKII from actin are mechanisms that stabilize the off state. The stability of the on state depends critically on intersubunit autophosphorylation, a process that restores any loss of pT286 due to phosphatase activity. Intersubunit autophosphorylation is also important in explaining why on state stability is not compromised by protein turnover. Recent evidence suggests that turnover occurs by subunit exchange. Thus, stability could be achieved if a newly inserted unphosphorylated subunit was autophosphorylated by a neighboring subunit. Based on other recent work, we posit a novel mechanism that enhances the stability of the on state by protection of pT286 from phosphatases. We posit that the binding of the NMNDAR to CaMKII forces pT286 into the catalytic site of a neighboring subunit, thereby protecting pT286 from phosphatases. A final principle concerns the role of structural changes. The binding of CaMKII to the NMDAR may act as a tag to organize the binding of further proteins that produce the synapse enlargement that underlies late LTP. We argue that these

Gas-phase complexes formed between amidoxime ligands and vanadium or iron investigated using electrospray ionization mass spectrometry.

Science.gov (United States)

Mustapha, Adetayo M; Pasilis, Sofie P

2016-08-15

Amidoxime-functionalized sorbents can be used to extract uranium from seawater. Iron(III) and vanadium(V) may compete with uranium for adsorption sites. We use 2,6-dihydroxyiminopiperidine (DHIP) and N(1) ,N(5) -dihydroxypentanediimidamide (DHPD) to model amidoxime functional groups and characterize the vanadium(V) and iron(III) complexes with these ligands. We also examine the effect of iron(III) and vanadium(V) on uranyl(VI) complexation by DHIP and DHPD. The experiments were carried out in positive ion mode using a quadrupole ion trap mass spectrometer equipped with an electrospray ionization source. The effect on the mass spectra of changes in ligand, metal:ligand mole ratio, and pH was examined. Iron(III) formed a 1:2 metal:ligand complex with DHIP at all metal:ligand mole ratios and pH values investigated; it formed both 1:2 and 1:3 metal:ligand complexes with DHPD. Vanadium(V) formed 1:1 and 1:2 metal:ligand complexes with DHIP. A 1:2 metal:ligand complex was formed with DHPD at all vanadium(V):DHPD mole ratios investigated. Changes in solution pH did not affect the ions observed. The relative binding affinities of the metal ions towards DHIP followed the order iron(III) > vanadium(V) > uranyl(VI). This study presents a first look at the gas-phase vanadium(V)- and iron(III)-DHIP and -DHPD complexes using electrospray ionization mass spectrometry. These metals form stronger complexes with amidoxime ligands than uranyl(VI), and will affect uranyl(VI) adsorption to amidoxime-based sorbents. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Tor forms a dimer through an N-terminal helical solenoid with a complex topology

Science.gov (United States)

Baretić, Domagoj; Berndt, Alex; Ohashi, Yohei; Johnson, Christopher M.; Williams, Roger L.

2016-04-01

The target of rapamycin (Tor) is a Ser/Thr protein kinase that regulates a range of anabolic and catabolic processes. Tor is present in two complexes, TORC1 and TORC2, in which the Tor-Lst8 heterodimer forms a common sub-complex. We have determined the cryo-electron microscopy (EM) structure of Tor bound to Lst8. Two Tor-Lst8 heterodimers assemble further into a dyad-symmetry dimer mediated by Tor-Tor interactions. The first 1,300 residues of Tor form a HEAT repeat-containing α-solenoid with four distinct segments: a highly curved 800-residue N-terminal 'spiral', followed by a 400-residue low-curvature 'bridge' and an extended `railing' running along the bridge leading to the 'cap' that links to FAT region. This complex topology was verified by domain insertions and offers a new interpretation of the mTORC1 structure. The spiral of one TOR interacts with the bridge of another, which together form a joint platform for the Regulatory Associated Protein of TOR (RAPTOR) regulatory subunit.

Automated local line rolling forming and simplified deformation simulation method for complex curvature plate of ships

Directory of Open Access Journals (Sweden)

Y. Zhao

2017-06-01

Full Text Available Local line rolling forming is a common forming approach for the complex curvature plate of ships. However, the processing mode based on artificial experience is still applied at present, because it is difficult to integrally determine relational data for the forming shape, processing path, and process parameters used to drive automation equipment. Numerical simulation is currently the major approach for generating such complex relational data. Therefore, a highly precise and effective numerical computation method becomes crucial in the development of the automated local line rolling forming system for producing complex curvature plates used in ships. In this study, a three-dimensional elastoplastic finite element method was first employed to perform numerical computations for local line rolling forming, and the corresponding deformation and strain distribution features were acquired. In addition, according to the characteristics of strain distributions, a simplified deformation simulation method, based on the deformation obtained by applying strain was presented. Compared to the results of the three-dimensional elastoplastic finite element method, this simplified deformation simulation method was verified to provide high computational accuracy, and this could result in a substantial reduction in calculation time. Thus, the application of the simplified deformation simulation method was further explored in the case of multiple rolling loading paths. Moreover, it was also utilized to calculate the local line rolling forming for the typical complex curvature plate of ships. Research findings indicated that the simplified deformation simulation method was an effective tool for rapidly obtaining relationships between the forming shape, processing path, and process parameters.

Fluorescence ratiometric sensing of polyols by phenylboronic acid complexes with ligands exhibiting excited-state intramolecular proton transfer in aqueous micellar media

Energy Technology Data Exchange (ETDEWEB)

Trejo-Huizar, Karla Elisa; Jiménez-Sánchez, Arturo; Martínez-Aguirre, Mayte A.; Yatsimirsky, Anatoly K., E-mail: anatoli@unam.mx

2016-11-15

2-Phenyl-3-hydroxy-4(1H)-quinolone possessing dual fluorescence due to excited-state intramolecular proton transfer (ESIPT) forms stable complex with phenylboronic acid with blue shifted emission maximum in micellar medium of a cationic surfactant even though the compound lacks required for complexation with boronic acids cis-diol structure. No complexation is observed in the presence of neutral or anionic surfactants. Titrations of this complex with polyols including sugars and nucleotides at pH 8 displace free quinolone showing ratiometric response, which allows determination of polyols with detection limits 0.05–1 mM and unusually wide linear dynamic ranges. Another ESIPT dye 2-(2′-hydroxyphenyl)−1H-benzimidazole also lacking cis-diol structure forms equally stable complex with phenylboronic acid and allows ratiometric determination of polyols with similar characteristics. The results of this study demonstrate that blocking ESIPT of signaling molecule by complexation of the receptor with the proton donor group eliminates the low energy emission from tautomeric form but strongly enhances the high energy emission typical for “normal” form of signaling molecule creating a possibility of ratiometric sensing.

Complex forming properties of natural organic acids. Pt. 2

International Nuclear Information System (INIS)

Ephraim, J.H.; Mathuthu, A.S.; Marinsky, J.A.

1990-07-01

An ultrafiltration technique combined with ion-selective-electrode and atomic absorption methods have been employed to obtain information on the complex forming properties of fulvic acid with iron and calcium. A model for interpreting complexation of metal ions to fulvic acid at any pH, medium ionic strength and metal to fulvic acid ratio developed earlier has been used in an attempt to predict the nature of iron and calcium interaction to Armadale Horizon Bh fulvic acid. Binding of calcium to fulvic acid which is enhanced at pHs greater than 6.0 has reasonably been predicted by the model taking into consideration complications due to the polyelectrolyte nature and the heterogeneity of the fulvic acid. The lack of agreement observed between the model predicted binding behavior and the experimentally observed results for the fulvic acid-iron system has been attributed to the formation of metal-induced aggregation. Reduction of Fe(III) to Fe(II) by the fulvic acid as reported by other workers is corroborated. (orig.)

Redox reactions of Cu(II)-amine complexes in aqueous solutions

International Nuclear Information System (INIS)

Kumbhar, A.G.; Kishore, Kamal

2003-01-01

A number of amines can be employed for all volatile treatment (AVT) of steam generator (SG) systems of nuclear power reactors. These amines form complexes with Cu 2+ and Ni 2+ ions which come into water due to corrosion. The redox reactions of a number of Cu(II)-AVT amine complexes and the stability of the transient species formed have been studied by pulse radiolysis technique. Rate constants for the reaction of e aq - with a number of Cu(II)-amine complexes have been determined by following the decay of e aq - absorption. Stability of Cu(I)-amine complexes was studied by following the kinetics of the bleaching signal formed at the λ max of the Cu(II) amine complex. Except for Cu(I)-triethanolamine complex all other Cu(I)-amine complexes were found to be stable. One-electron oxidation of Cu(II) amine complexes was studied using azidyl radicals for the oxidation reaction as OH radicals react with the alcohol groups present in the amines used in this study. Cu(III)-amine complexes were found to be unstable and decayed by second-order kinetics

Elg1 forms an alternative RFC complex important for DNA replication and genome integrity

NARCIS (Netherlands)

Bellaoui, Mohammed; Chang, Michael; Ou, Jiongwen; Xu, Hong; Boone, Charles; Brown, Grant W

2003-01-01

Genome-wide synthetic genetic interaction screens with mutants in the mus81 and mms4 replication fork-processing genes identified a novel replication factor C (RFC) homolog, Elg1, which forms an alternative RFC complex with Rfc2-5. This complex is distinct from the DNA replication RFC, the DNA

Experimental and numerical investigation of form-stable dodecane/hydrophobic fumed silica composite phase change materials for cold energy storage

International Nuclear Information System (INIS)

Chen, Jiajie; Ling, Ziye; Fang, Xiaoming; Zhang, Zhengguo

2015-01-01

Highlights: • Form-stable dodecane/fumed silica composite for cold storage is prepared. • A suggesting hypothesis that explains infiltration mechanism is proposed. • The performance of the composite phase change material is investigated. • Numerical simulation of system is carried out and results fit well. - Abstract: A kind of form-stable composite phase change materials used for cold thermal energy storage is prepared by absorbing dodecane into the hydrophobic fumed silica. With relatively suitable pore diameter and hydrophobic groups, hydrophobic fumed silica is beneficial to the penetration and infiltration of dodecane and the leakage problem solving. Scanned by electron micrographs and Fourier transformation infrared, the composite phase change material is characterized to be just physical penetration. Besides, the differential scanning calorimeter and thermo gravimetric analysis reveals the high enthalpy, good thermal stability and cycling performance of this composite phase change material. What’s more, Hot-Disk thermal constants analyzer demonstrates that the composite phase change material has low thermal conductivity which is desired in cold storage application. In the experiment, a cold energy storage system is set up and the results from the experiment show that the system has excellent performance of cold storage by incorporating composite phase change material. Apart from that, the experimental data is found to have a great agreement with the numerical simulation which is carried out by using the commercial computational fluid dynamics software FLUENT.

Determination of UO2(II), and Ce(III) complexes formed with halogen and nitro derivatives of 8-hydroxyquinoline

International Nuclear Information System (INIS)

Teksoez, S.; Uenak, P.

2001-01-01

Proton-ligand stability constants for some iodo and nitro derivatives of 8-hydroxyquinoline were determined by Calvin Bjerrum potantiometrical method. The stability constants of the corresponding chelates with UO 2 (II), Th(IV) and Ce(III) were studied potentiometrically at 25 degree Celsius by applying Irving-Rossotti computing method. The complexes of the nitro-substituted ligands were less stable than the corresponding complexes of the unsubstituted ligands. The stability constants of metal-ligands depend on the ionic radii and ionic charge of metals and also they decrease with steric repulsions of the nitro groups

High Molecular Weight Forms of Mammalian Respiratory Chain Complex II

Czech Academy of Sciences Publication Activity Database

Kovářová, Nikola; Mráček, Tomáš; Nůsková, Hana; Holzerová, Eliška; Vrbacký, Marek; Pecina, Petr; Hejzlarová, Kateřina; Klučková, Katarína; Rohlena, Jakub; Neužil, Jiří; Houštěk, Josef

2013-01-01

Roč. 8, č. 8 (2013), e71869 E-ISSN 1932-6203 R&D Projects: GA ČR(CZ) GPP303/10/P227; GA MŠk(CZ) LL1204; GA MZd(CZ) NT12370; GA ČR(CZ) GAP301/10/1937 Institutional research plan: CEZ:AV0Z50520701 Institutional support: RVO:67985823 Keywords : supercomplexes * high molecular weihgt forms of complex II * native electrophoretic systems Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 3.534, year: 2013

Uses of stable isotopes

International Nuclear Information System (INIS)

Axente, Damian

1998-01-01

The most important fields of stable isotope use with examples are presented. These are: 1. Isotope dilution analysis: trace analysis, measurements of volumes and masses; 2. Stable isotopes as tracers: transport phenomena, environmental studies, agricultural research, authentication of products and objects, archaeometry, studies of reaction mechanisms, structure and function determination of complex biological entities, studies of metabolism, breath test for diagnostic; 3. Isotope equilibrium effects: measurement of equilibrium effects, investigation of equilibrium conditions, mechanism of drug action, study of natural processes, water cycle, temperature measurements; 4. Stable isotope for advanced nuclear reactors: uranium nitride with 15 N as nuclear fuel, 157 Gd for reactor control. In spite of some difficulties of stable isotope use, particularly related to the analytical techniques, which are slow and expensive, the number of papers reporting on this subject is steadily growing as well as the number of scientific meetings organized by International Isotope Section and IAEA, Gordon Conferences, and regional meeting in Germany, France, etc. Stable isotope application development on large scale is determined by improving their production technologies as well as those of labeled compound and the analytical techniques. (author)

Synthesis and characterization of thermally stable oligomer-metal ...

African Journals Online (AJOL)

The thermal stabilities of the oligomer-metal complexes were compared by thermogravimetric (TG) and differential thermal (DTA) analyses. According to TG, oligomer-metal complexes were stable against to temperature and thermooxidative decomposition. The weight losses of oligomer-metal complexes were found to be 5 ...

Forming the management model in industrial partnerships of the machine-building complex of Ukraine

OpenAIRE

Reshetilova, T.; Kuvaieva, T.

2016-01-01

Stages of development the processes of forming the industrial networks, technological and logistic chains, partnership and their varieties are analyzed. Factors that determine the rate and scale of the process of forming the partnerships in the machine-building complex of Ukraine are established. A group of the factors that lead to forming the vertical partnership based on Partner Relationship Management (PRM) in mining machinery and mining industry are determined and analyzed. It is possible...

Complex forms of mitochondrial DNA in human B cells transformed by Epstein-Barr virus (EBV)

DEFF Research Database (Denmark)

Christiansen, Gunna; Christiansen, C; Zeuthen, J

1983-01-01

Human lymphocytes and lymphoid cell lines were analyzed for the presence of complex forms of mitochondrial DNA (mtDNA) by electron microscopy. A high frequency (9%-14.5%) of catenated dimers, circular dimers, or oligomers were found in samples from Epstein-Barr-virus-(EBV) transformed lymphoblast......Human lymphocytes and lymphoid cell lines were analyzed for the presence of complex forms of mitochondrial DNA (mtDNA) by electron microscopy. A high frequency (9%-14.5%) of catenated dimers, circular dimers, or oligomers were found in samples from Epstein-Barr-virus-(EBV) transformed...

Humic substances in natural waters and their complexation with trace metals and radionuclides: a review

International Nuclear Information System (INIS)

Boggs, S. Jr.; Livermore, D.; Seitz, M.G.

1985-07-01

Dissolved humic substances (humic and fulvic acids) occur in surface waters and groundwaters in concentrations ranging from less than 1 mg(C)/L to more than 100 mg(C)/L. Humic substances are strong complexing agents for many trace metals in the environment and are also capable of forming stable soluble complexes or chelates with radionuclides. Concentrations of humic materials as low as 1 mg(C)/L can produce a detectable increase in the mobility of some actinide elements by forming soluble complexes that inhibit sorption of the radionuclides onto rock materials. The stability of trace metal- or radionuclide-organic complexes is commonly measured by an empirically determined conditional stability constant (K'), which is based on the ratio of complexed metal (radionuclide) in solution to the product concentration of uncomplexed metal and humic complexant. Larger values of stability constants indicate greater complex stability. The stability of radionuclide-organic complexes is affected both by concentration variables and envionmental factors. In general, complexing is favored by increased of radionuclide, increased pH, and decreased ionic strength. Actinide elements are generally most soluble in their higher oxidation states. Radionuclides can also form stable, insoluble complexes with humic materials that tend to reduce radionuclide mobility. These insoluble complexes may be radionuclide-humate colloids that subsequently precipitate from solution, or complexes of radionuclides and humic substances that sorb to clay minerals or other soil particulates strongly enough to immobilize the radionuclides. Colloid formation appears to be favored by increased radionuclide concentration and lowered pH; however, the conditions that favor formation of insoluble complexes that sorb to particulates are still poorly understood. 129 refs., 25 figs., 19 tabs

Machine-Building for Fuel and Energy Complex: Perspective Forms of Interaction

Science.gov (United States)

Nikitenko, S. M.; Goosen, E. V.; Pakhomova, E. A.; Rozhkova, O. V.; Mesyats, M. A.

2017-10-01

The article is devoted to the study of the existing forms of cooperation between the authorities, business and science in the fuel and energy complex and the machine-building industry at the regional level. The possibilities of applying the concept of the “triple helix” and its multi-helix modifications for the implementation of the import substitution program for high- tech products have been considered.

Crystallographic and theoretical studies of an inclusion complex of β-cyclodextrin with fentanyl.

Science.gov (United States)

Ogawa, Noriko; Nagase, Hiromasa; Loftsson, Thorsteinn; Endo, Tomohiro; Takahashi, Chisato; Kawashima, Yoshiaki; Ueda, Haruhisa; Yamamoto, Hiromitsu

2017-10-15

The crystal structure of an inclusion complex of β-cyclodextrin (β-CD) with fentanyl was determined by single crystal X-ray diffraction analysis. The crystal belongs to the triclinic space group P1 and the complex comprises one fentanyl, two β-CD, and several water molecules. β-CD and fentanyl form a host-guest inclusion complex at a ratio of 2:1 and the asymmetric unit of the complex contains two host molecules (β-CDs) in a head-to-head arrangement that form dimers through hydrogen bonds between the secondary hydroxyl groups of β-CD and one guest molecule. Fentanyl is totally contained within the β-CD cavity and the structure of the phenylethyl part of fentanyl inside the dimeric cavity of the complex is disordered. Furthermore, theoretical molecular conformational calculations were conducted to clarify the mobility of the guest molecule in the β-CD cavity using CONFLEX software. Crystal optimization and crystal energy calculations were also conducted. The results of the theoretical calculations confirmed that the conformation of disorder part 1, which was high in occupancy by crystal structure analysis, was more stable. The phenylethyl part of fentanyl existed in several stable conformations. Copyright © 2017 Elsevier B.V. All rights reserved.

Host-derived, pore-forming toxin-like protein and trefoil factor complex protects the host against microbial infection.

Science.gov (United States)

Xiang, Yang; Yan, Chao; Guo, Xiaolong; Zhou, Kaifeng; Li, Sheng'an; Gao, Qian; Wang, Xuan; Zhao, Feng; Liu, Jie; Lee, Wen-Hui; Zhang, Yun

2014-05-06

Aerolysins are virulence factors belonging to the bacterial β-pore-forming toxin superfamily. Surprisingly, numerous aerolysin-like proteins exist in vertebrates, but their biological functions are unknown. βγ-CAT, a complex of an aerolysin-like protein subunit (two βγ-crystallin domains followed by an aerolysin pore-forming domain) and two trefoil factor subunits, has been identified in frogs (Bombina maxima) skin secretions. Here, we report the rich expression of this protein, in the frog blood and immune-related tissues, and the induction of its presence in peritoneal lavage by bacterial challenge. This phenomena raises the possibility of its involvement in antimicrobial infection. When βγ-CAT was administrated in a peritoneal infection model, it greatly accelerated bacterial clearance and increased the survival rate of both frogs and mice. Meanwhile, accelerated Interleukin-1β release and enhanced local leukocyte recruitments were determined, which may partially explain the robust and effective antimicrobial responses observed. The release of interleukin-1β was potently triggered by βγ-CAT from the frog peritoneal cells and murine macrophages in vitro. βγ-CAT was rapidly endocytosed and translocated to lysosomes, where it formed high molecular mass SDS-stable oligomers (>170 kDa). Lysosomal destabilization and cathepsin B release were detected, which may explain the activation of caspase-1 inflammasome and subsequent interleukin-1β maturation and release. To our knowledge, these results provide the first functional evidence of the ability of a host-derived aerolysin-like protein to counter microbial infection by eliciting rapid and effective host innate immune responses. The findings will also largely help to elucidate the possible involvement and action mechanisms of aerolysin-like proteins and/or trefoil factors widely existing in vertebrates in the host defense against pathogens.

Optimizing structure of complex technical system by heterogeneous vector criterion in interval form

Science.gov (United States)

Lysenko, A. V.; Kochegarov, I. I.; Yurkov, N. K.; Grishko, A. K.

2018-05-01

The article examines the methods of development and multi-criteria choice of the preferred structural variant of the complex technical system at the early stages of its life cycle in the absence of sufficient knowledge of parameters and variables for optimizing this structure. The suggested methods takes into consideration the various fuzzy input data connected with the heterogeneous quality criteria of the designed system and the parameters set by their variation range. The suggested approach is based on the complex use of methods of interval analysis, fuzzy sets theory, and the decision-making theory. As a result, the method for normalizing heterogeneous quality criteria has been developed on the basis of establishing preference relations in the interval form. The method of building preferential relations in the interval form on the basis of the vector of heterogeneous quality criteria suggest the use of membership functions instead of the coefficients considering the criteria value. The former show the degree of proximity of the realization of the designed system to the efficient or Pareto optimal variants. The study analyzes the example of choosing the optimal variant for the complex system using heterogeneous quality criteria.

Group living in squamate reptiles: a review of evidence for stable aggregations.

Science.gov (United States)

Gardner, Michael G; Pearson, Sarah K; Johnston, Gregory R; Schwarz, Michael P

2016-11-01

How sociality evolves and is maintained remains a key question in evolutionary biology. Most studies to date have focused on insects, birds, and mammals but data from a wider range of taxonomic groups are essential to identify general patterns and processes. The extent of social behaviour among squamate reptiles is under-appreciated, yet they are a promising group for further studies. Living in aggregations is posited as an important step in the evolution of more complex sociality. We review data on aggregations among squamates and find evidence for some form of aggregations in 94 species across 22 families. Of these, 18 species across 7 families exhibited 'stable' aggregations that entail overlapping home ranges and stable membership in long-term (years) or seasonal aggregations. Phylogenetic analysis suggests that stable aggregations have evolved multiple times in squamates. We: (i) identify significant gaps in our understanding; (ii) outline key traits which should be the focus of future research; and (iii) outline the potential for utilising reproductive skew theory to provide insights into squamate sociality. © 2015 Cambridge Philosophical Society.

Osmium(VI) complexes as a new class of potential anti-cancer agents.

Science.gov (United States)

Ni, Wen-Xiu; Man, Wai-Lun; Cheung, Myra Ting-Wai; Sun, Raymond Wai-Yin; Shu, Yuan-Lan; Lam, Yun-Wah; Che, Chi-Ming; Lau, Tai-Chu

2011-02-21

A nitridoosmium(VI) complex [Os(VI)(N)(sap)(OH(2))Cl] (H(2)sap = N-salicylidene-2-aminophenol) displays prominent in vitro and in vivo anti-cancer properties, induces S- and G2/M-phase arrest and forms a stable adduct with dianionic 5'-guanosine monophosphate.

Stable and rigid DTPA-like paramagnetic tags suitable for in vitro and in situ protein NMR analysis.

Science.gov (United States)

Chen, Jia-Liang; Zhao, Yu; Gong, Yan-Jun; Pan, Bin-Bin; Wang, Xiao; Su, Xun-Cheng

2018-02-01

Organic synthesis of a ligand with high binding affinities for paramagnetic lanthanide ions is an effective way of generating paramagnetic effects on proteins. These paramagnetic effects manifested in high-resolution NMR spectroscopy are valuable dynamic and structural restraints of proteins and protein-ligand complexes. A paramagnetic tag generally contains a metal chelating moiety and a reactive group for protein modification. Herein we report two new DTPA-like tags, 4PS-PyDTTA and 4PS-6M-PyDTTA that can be site-specifically attached to a protein with a stable thioether bond. Both protein-tag adducts form stable lanthanide complexes, of which the binding affinities and paramagnetic tensors are tunable with respect to the 6-methyl group in pyridine. Paramagnetic relaxation enhancement (PRE) effects of Gd(III) complex on protein-tag adducts were evaluated in comparison with pseudocontact shift (PCS), and the results indicated that both 4PS-PyDTTA and 4PS-6M-PyDTTA tags are rigid and present high-quality PREs that are crucially important in elucidation of the dynamics and interactions of proteins and protein-ligand complexes. We also show that these two tags are suitable for in-situ protein NMR analysis.

Segregation and persistence of form in the lateral occipital complex.

Science.gov (United States)

Ferber, Susanne; Humphrey, G Keith; Vilis, Tutis

2005-01-01

While the lateral occipital complex (LOC) has been shown to be implicated in object recognition, it is unclear whether this brain area is responsive to low-level stimulus-driven features or high-level representational processes. We used scrambled shape-from-motion displays to disambiguate the presence of contours from figure-ground segregation and to measure the strength of the binding process for shapes without contours. We found persisting brain activation in the LOC for scrambled displays after the motion stopped indicating that this brain area subserves and maintains figure-ground segregation processes, a low-level function in the object processing hierarchy. In our second experiment, we found that the figure-ground segregation process has some form of spatial constancy indicating top-down influences. The persisting activation after the motion stops suggests an intermediate role in object recognition processes for this brain area and might provide further evidence for the idea that the lateral occipital complex subserves mnemonic functions mediating between iconic and short-term memory.

Complex cobordism and stable homotopy groups of spheres

CERN Document Server

Ravenel, Douglas C

2003-01-01

Since the publication of its first edition, this book has served as one of the few available on the classical Adams spectral sequence, and is the best account on the Adams-Novikov spectral sequence. This new edition has been updated in many places, especially the final chapter, which has been completely rewritten with an eye toward future research in the field. It remains the definitive reference on the stable homotopy groups of spheres. The first three chapters introduce the homotopy groups of spheres and take the reader from the classical results in the field though the computational aspects

Photophysical and physicochemical studies of rare earths complexes formed with calyx(n)arenes

International Nuclear Information System (INIS)

Ramirez, F.M.; Varbanov, S.; Corine, C.; Muller, G.; Fatin-Rouge, N.; Scopelliti, R.; Bunzli J, C.G.

2001-01-01

In this work, some of the photophysical and physicochemical properties are presented which are observed in the rare earths complexes that are formed with diverse functionalized calyx(n)arenes receptors where n=4-6 designed with predetermined properties and synthesized by own methods. (Author)

Electrically active induced energy levels and metastability of B and N vacancy-complexes in 4H–SiC

Science.gov (United States)

Igumbor, E.; Olaniyan, O.; Mapasha, R. E.; Danga, H. T.; Omotoso, E.; Meyer, W. E.

2018-05-01

Electrically active induced energy levels in semiconductor devices could be beneficial to the discovery of an enhanced p or n-type semiconductor. Nitrogen (N) implanted into 4H–SiC is a high energy process that produced high defect concentrations which could be removed during dopant activation annealing. On the other hand, boron (B) substituted for silicon in SiC causes a reduction in the number of defects. This scenario leads to a decrease in the dielectric properties and induced deep donor and shallow acceptor levels. Complexes formed by the N, such as the nitrogen-vacancy centre, have been reported to play a significant role in the application of quantum bits. In this paper, results of charge states thermodynamic transition level of the N and B vacancy-complexes in 4H–SiC are presented. We explore complexes where substitutional N/N or B/B sits near a Si (V) or C (V) vacancy to form vacancy-complexes (NV, NV, NV, NV, BV, BV, BV and BV). The energies of formation of the N related vacancy-complexes showed the NV to be energetically stable close to the valence band maximum in its double positive charge state. The NV is more energetically stable in the double negative charge state close to the conduction band minimum. The NV on the other hand, induced double donor level and the NV induced a double acceptor level. For B related complexes, the BV and BV were energetically stable in their single positive charge state close to the valence band maximum. As the Fermi energy is varied across the band gap, the neutral and single negative charge states of the BV become more stable at different energy levels. B and N related complexes exhibited charge state controlled metastability behaviour.

Does the centre of mass remain stable during complex human postural equilibrium tasks in weightlessness?

Science.gov (United States)

Stapley, Paul; Pozzo, Thierry

In normal gravity conditions the execution of voluntary movement involves the displacement of body segments as well as the maintenance of a stable reference value for equilibrium control. It has been suggested that centre of mass (CM) projection within the supporting base (BS) is the stabilised reference for voluntary action, and is conserved in weightlessness. The purpose of this study was to determine if the CM is stabilised during whole body reaching movements executed in weightlessness. The reaching task was conducted by two cosmonauts aboard the Russian orbital station MIR, during the Franco-Russian mission ALTAIR, 1993. Movements of reflective markers were recorded using a videocamera, successive images being reconstructed by computer every 40ms. The position of the CM, ankle joint torques and shank and thigh angles were computed for each subject pre- in- and post-flight using a 7-link mathematical model. Results showed that both cosmonauts adopted a backward leaning posture prior to reaching movements. Inflight, the CM was displaced throughout values in the horizontal axis three times those of pre-flight measures. In addition, ankle dorsi flexor torques inflight increased to values double those of pre- and post-flight tests. This study concluded that CM displacements do not remain stable during complex postural equilibrium tasks executed in weightlessness. Furthermore, in the absence of gravity, subjects changed their strategy for producing ankle torque during spaceflight from a forward to a backward leaning posture.

MURC/Cavin-4 and cavin family members form tissue-specific caveolar complexes.

Science.gov (United States)

Bastiani, Michele; Liu, Libin; Hill, Michelle M; Jedrychowski, Mark P; Nixon, Susan J; Lo, Harriet P; Abankwa, Daniel; Luetterforst, Robert; Fernandez-Rojo, Manuel; Breen, Michael R; Gygi, Steven P; Vinten, Jorgen; Walser, Piers J; North, Kathryn N; Hancock, John F; Pilch, Paul F; Parton, Robert G

2009-06-29

Polymerase I and transcript release factor (PTRF)/Cavin is a cytoplasmic protein whose expression is obligatory for caveola formation. Using biochemistry and fluorescence resonance energy transfer-based approaches, we now show that a family of related proteins, PTRF/Cavin-1, serum deprivation response (SDR)/Cavin-2, SDR-related gene product that binds to C kinase (SRBC)/Cavin-3, and muscle-restricted coiled-coil protein (MURC)/Cavin-4, forms a multiprotein complex that associates with caveolae. This complex can constitutively assemble in the cytosol and associate with caveolin at plasma membrane caveolae. Cavin-1, but not other cavins, can induce caveola formation in a heterologous system and is required for the recruitment of the cavin complex to caveolae. The tissue-restricted expression of cavins suggests that caveolae may perform tissue-specific functions regulated by the composition of the cavin complex. Cavin-4 is expressed predominantly in muscle, and its distribution is perturbed in human muscle disease associated with Caveolin-3 dysfunction, identifying Cavin-4 as a novel muscle disease candidate caveolar protein.

(Pyridine)(tetrahydroborato)zinc complex, (Zn(BH4)2(py)), as a new stable, efficient and chemoselective reducing agent for reduction of carbonyl compounds

International Nuclear Information System (INIS)

Zeynizadeh, Behzad; Faraji, Fariba

2003-01-01

(Pyridine)(tetrahydroborato)zinc complex, (Zn(BH 4 ) 2 (py)), as a stable white solid, was prepared quantitatively by complexation of an equimolar amount of zinc tetrahydroborate and pyridine at room temperature. This reagent can easily reduce variety of carbonyl compounds such as aldehydes, ketones, acyloins, α-diketones and α,β-unsaturated carbonyl compounds to their corresponding alcohols in good to excellent yields. Reduction reactions were performed in ether or THF at room temperature or under reflux conditions. In addition, the chemoselective reduction of aldehydes over ketones was accomplished successfully with this reducing agent

Humic substances in natural waters and their complexation with trace metals and radionuclides: a review. [129 references

Energy Technology Data Exchange (ETDEWEB)

Boggs, S. Jr.; Livermore, D.; Seitz, M.G.

1985-07-01

Dissolved humic substances (humic and fulvic acids) occur in surface waters and groundwaters in concentrations ranging from less than 1 mg(C)/L to more than 100 mg(C)/L. Humic substances are strong complexing agents for many trace metals in the environment and are also capable of forming stable soluble complexes or chelates with radionuclides. Concentrations of humic materials as low as 1 mg(C)/L can produce a detectable increase in the mobility of some actinide elements by forming soluble complexes that inhibit sorption of the radionuclides onto rock materials. The stability of trace metal- or radionuclide-organic complexes is commonly measured by an empirically determined conditional stability constant (K'), which is based on the ratio of complexed metal (radionuclide) in solution to the product concentration of uncomplexed metal and humic complexant. Larger values of stability constants indicate greater complex stability. The stability of radionuclide-organic complexes is affected both by concentration variables and envionmental factors. In general, complexing is favored by increased of radionuclide, increased pH, and decreased ionic strength. Actinide elements are generally most soluble in their higher oxidation states. Radionuclides can also form stable, insoluble complexes with humic materials that tend to reduce radionuclide mobility. These insoluble complexes may be radionuclide-humate colloids that subsequently precipitate from solution, or complexes of radionuclides and humic substances that sorb to clay minerals or other soil particulates strongly enough to immobilize the radionuclides. Colloid formation appears to be favored by increased radionuclide concentration and lowered pH; however, the conditions that favor formation of insoluble complexes that sorb to particulates are still poorly understood. 129 refs., 25 figs., 19 tabs.

Synergistic effect of signaling from receptors of soluble platelet agonists and outside-in signaling in formation of a stable fibrinogen-integrin αIIbβ3-actin cytoskeleton complex.

Science.gov (United States)

Budnik, Ivan; Shenkman, Boris; Savion, Naphtali

2015-01-01

Thrombus formation in the injured vessel wall is a highly complex process involving various blood-born components that go through specific temporal and spatial changes as observed by intravital videomicroscopy. Platelets bind transiently to the developing thrombus and may either become stably incorporated into or disengage from the thrombus. The aim of the present study was to reveal the processes involved in the formation of a stable thrombus. Platelet-rich plasma and washed platelets were studied by the aggregometer. The aggregate stability was challenged by eptifibatide. Platelet Triton-insoluble fraction was prepared and the actin and αIIb content in the cytoskeleton was analyzed by western blot. Maximal actin polymerization is achieved 1min after platelet activation while maximal αIIbβ3-actin cytoskeleton association requires 5 to 10min of activation and fibrinogen-mediated platelet-to-platelet bridging. Thus, actin polymerization is dependent on platelet activation and requires neither αIIbβ3 integrin occupation nor platelet aggregation. Formation of a stable aggregate requires platelet activation for more than 1min, complete increase in actin cytoskeleton fraction and partial association of αIIbβ3 with the actin cytoskeleton. However, direct αIIbβ3 activation is not sufficient for cytoskeleton complex formation. Thus, stable αIIbβ3-fibrinogen interaction, representing stable aggregate, is achieved after more than 1min agonist activation, involving inside-out and outside-in signaling but not after direct integrin activation, involving only outside-in signaling. Formation of a stable fibrinogen-αIIbβ3-actin cytoskeleton complex is the result of the combined effect of platelet stimulation by soluble agonists, activation of αIIbβ3, fibrinogen binding and platelet-to-platelet bridging. Copyright © 2014 Elsevier Ltd. All rights reserved.

Thermal stability of the complex formed between carotenoids from sea buckthorn (Hippophae rhamnoides L.) and bovine β-lactoglobulin

Science.gov (United States)

Aprodu, Iuliana; Ursache, Florentina-Mihaela; Turturică, Mihaela; Râpeanu, Gabriela; Stănciuc, Nicoleta

2017-02-01

Sea buckthorn has gained importance as a versatile nutraceutical, due to its high nutritive value in terms of carotenoids content. β-Lactoglobulin (β-LG) is a natural carrier for various bioactive compounds. In this study, the effect of thermal treatment in the temperature range of 25 to 100 °C for 15 min on the complex formed by β-LG and carotenoids from sea buckthorn was reported, based on fluorescence spectroscopy, molecular docking and molecular dynamics simulation results. Also, the berries extracts were analyzed for their carotenoids content. The chromatographic profile of the sea buckthorn extracts revealed the presence of zeaxanthin and β-carotene, as major compounds. The Stern-Volmer constants and binding parameters between β-LG and β-carotene were estimated based on quenching experiments. When thermally treating the β-LG-carotenoids mixtures, an increase in intrinsic and extrinsic fluorescence intensity up to 90 °C was observed, together with blue-shifts in maximum emission in the lower temperature range and red-shifts at higher temperature. Based on fluorescence spectroscopy results, the unfolding of the protein molecules at high temperature was suggested. Detailed information obtained at atomic level revealed that events taking place in the complex heated at high temperature caused important changes in the β-carotene binding site, therefore leading to a more thermodynamically stable assembly. This study can be used to understand the changes occurring at molecular level that could help food operators to design new ingredients and functional foods, and to optimize the processing methods in order to obtain healthier food products.

Stable dissipative optical vortex clusters by inhomogeneous effective diffusion.

Science.gov (United States)

Li, Huishan; Lai, Shiquan; Qui, Yunli; Zhu, Xing; Xie, Jianing; Mihalache, Dumitru; He, Yingji

2017-10-30

We numerically show the generation of robust vortex clusters embedded in a two-dimensional beam propagating in a dissipative medium described by the generic cubic-quintic complex Ginzburg-Landau equation with an inhomogeneous effective diffusion term, which is asymmetrical in the two transverse directions and periodically modulated in the longitudinal direction. We show the generation of stable optical vortex clusters for different values of the winding number (topological charge) of the input optical beam. We have found that the number of individual vortex solitons that form the robust vortex cluster is equal to the winding number of the input beam. We have obtained the relationships between the amplitudes and oscillation periods of the inhomogeneous effective diffusion and the cubic gain and diffusion (viscosity) parameters, which depict the regions of existence and stability of vortex clusters. The obtained results offer a method to form robust vortex clusters embedded in two-dimensional optical beams, and we envisage potential applications in the area of structured light.

Chaos synchronization and chaotization of complex chaotic systems in series form by optimal control

International Nuclear Information System (INIS)

Ge Zhengming; Yang, C.-H.

2009-01-01

By the method of quadratic optimum control, a quadratic optimal regulator is used for synchronizing two complex chaotic systems in series form. By this method the least error with less control energy is achieved, and the optimization on both energy and error is realized synthetically. The simulation results of two Quantum-CNN chaos systems in series form prove the effectiveness of this method. Finally, chaotization of the system is given by optimal control.

Superoxide scavenging activity of pirfenidone-iron complex

International Nuclear Information System (INIS)

Mitani, Yoshihiro; Sato, Keizo; Muramoto, Yosuke; Karakawa, Tomohiro; Kitamado, Masataka; Iwanaga, Tatsuya; Nabeshima, Tetsuji; Maruyama, Kumiko; Nakagawa, Kazuko; Ishida, Kazuhiko; Sasamoto, Kazumi

2008-01-01

Pirfenidone (PFD) is focused on a new anti-fibrotic drug, which can minimize lung fibrosis etc. We evaluated the superoxide (O 2 ·- ) scavenging activities of PFD and the PFD-iron complex by electron spin resonance (ESR) spectroscopy, luminol-dependent chemiluminescence assay, and cytochrome c reduction assay. Firstly, we confirmed that the PFD-iron complex was formed by mixing iron chloride with threefold molar PFD, and the complex was stable in distillated water and ethanol. Secondary, the PFD-iron complex reduced the amount of O 2 ·- produced by xanthine oxidase/hypoxanthine without inhibiting the enzyme activity. Thirdly, it also reduced the amount of O 2 ·- released from phorbor ester-stimulated human neutrophils. PFD alone showed few such effects. These results suggest the possibility that the O 2 ·- scavenging effect of the PFD-iron complex contributes to the anti-fibrotic action of PFD used for treating idiopathic pulmonary fibrosis

Numerical and experimental study on temperature control of solar panels with form-stable paraffin/expanded graphite composite PCM

International Nuclear Information System (INIS)

Luo, Zigeng; Huang, Zhaowen; Xie, Ning; Gao, Xuenong; Xu, Tao; Fang, Yutang; Zhang, Zhengguo

2017-01-01

Highlights: • A passive cooling PV-PCM system was developed. • Form-stable paraffin/EG composite PCM with high thermal conductivity was utilized. • Numerical simulation on the temperature of PV-PCM panel was carried out. • Effects of density were studied under the given weather conditions. - Abstract: Performance of photovoltaic (PV) panels is greatly affected by its operating temperature. And traditional active and passive cooling methods usually suffer from the disadvantages of external energy consumption, uneven temperature distribution and low thermal conductivity of phase change materials (PCMs). In this work, a PV-PCM system was developed to control the temperature of a PV panel by applying high thermal conductive form-stable paraffin (ZDJN-28)/EG composite PCM. The temperature, output voltage and power of a conventional PV panel and the PV-PCM panel were measured and compared. A numerical simulation model established by CFD software FLUENT was used to simulate the temperature change process of the PV-PCM panel with different material densities under the same conditions as experiment. The experiment results showed that compared with the temperature of the conventional PV panel, the temperature of the PV-PCM panel is kept below 50 °C for 200 min extended by 146 min with output power averagely increased by 7.28% in heating process. Simulated temperatures were in good agreement with experimental temperatures and indicated that the higher the density of the PCM is, the better the temperature management performance the PV panel could achieve. Besides, the PCM with density of 900 kg/m 3 was found sufficient to achieve a good temperature management performance when the average ambient temperature below 25 °C with the highest solar irradiation of 901 w/m 2 . In summary, this work is of great importance in the design of a PV-PCM system for temperature management of PV panels.

Characteristic Ligand-Induced Crystal Forms of HIV-1 Protease Complexes: A Novel Discovery of X-Ray Crystallography

International Nuclear Information System (INIS)

Olajuyigbe, Folasade M.; Geremia, Silvano

2009-10-01

Mixtures of saquinavir (SQV) and ritonavir (RTV) were cocrystallized with HIV-1 protease (PR) in an attempt to compare their relative potencies using a crystallographic approach and factors responsible for the respective crystal forms obtained were examined. The mixture ratio of the SQV/RTV was in the range of 1:1 to 1:50 with increasing concentration of dimethyl sulphoxide (DMSO) used. Two crystal forms of PR complexes were obtained. At concentrations of 0.8 and 1.2 % DMSO using 1:1 and 1:15 ratios of SQV/RTV, the crystal form was monoclinic while increasing the concentration of DMSO to 3.2 and 5.0% using 1:15 and 1:50 ratios of SQV/RTV, the orthorhombic crystal form was obtained. The high resolution X-ray crystal structures of the PR/ inhibitor complexes reveal that crystal forms with respective space groups are dependent on the occupancy of either SQV or RTV in the active site of the PR. The occupancy of either of the PR inhibitors in the active site of PR has interestingly demonstrated unique cooperativity effects in crystallization of protein-ligand complexes. The crystal forms obtained were also related to the concentration of DMSO and ammonium sulphate in crystallization, and storage conditions of purified PR. Surprisingly, the relative occupancies of these inhibitors in the active site suggested a competition between the two inhibitors which were not inhibition constants related. Analysis of the structures in both crystal forms show no difference in DMSO content but at higher concentration of DMSO (3.2 - 5.0%) in the orthorhombic crystal forms, there were protein-sulphate interactions which were absent in the monoclinic forms with lower concentration (0.8 - 1.2%) of DMSO. This work has clearly demonstrated that there is cooperativity in crystallization and the conditions of crystallization influence specific intermolecular contacts in crystal packing (crystal form). (author)

Perception and the strongest sensory memory trace of multi-stable displays both form shortly after the stimulus onset.

Science.gov (United States)

Pastukhov, Alexander

2016-02-01

We investigated the relation between perception and sensory memory of multi-stable structure-from-motion displays. The latter is an implicit visual memory that reflects a recent history of perceptual dominance and influences only the initial perception of multi-stable displays. First, we established the earliest time point when the direction of an illusory rotation can be reversed after the display onset (29-114 ms). Because our display manipulation did not bias perception towards a specific direction of illusory rotation but only signaled the change in motion, this means that the perceptual dominance was established no later than 29-114 ms after the stimulus onset. Second, we used orientation-selectivity of sensory memory to establish which display orientation produced the strongest memory trace and when this orientation was presented during the preceding prime interval (80-140 ms). Surprisingly, both estimates point towards the time interval immediately after the display onset, indicating that both perception and sensory memory form at approximately the same time. This suggests a tighter integration between perception and sensory memory than previously thought, warrants a reconsideration of its role in visual perception, and indicates that sensory memory could be a unique behavioral correlate of the earlier perceptual inference that can be studied post hoc.

A pH-responsive carboxylic β-1,3-glucan polysaccharide for complexation with polymeric guests.

Science.gov (United States)

Lien, Le Thi Ngoc; Shiraki, Tomohiro; Dawn, Arnab; Tsuchiya, Youichi; Tokunaga, Daisuke; Tamaru, Shun-ichi; Enomoto, Naoya; Hojo, Junichi; Shinkai, Seiji

2011-06-07

The helix-forming nature of β-1,3-glucan polysaccharides is a characteristic that has potential for producing gene carriers, bio-nanomaterials and other chiral nanowires. Herein, carboxylic curdlan (CurCOOH) bearing the β-1,3-polyglucuronic acid structure was successfully prepared from β-1,3-glucan polysaccharide curdlan (Cur) by one-step oxidation using a 4-acetamido-TEMPO/NaClO/NaClO(2) system as the oxidant. The resulting high-molecular-weight CurCOOH was proved to bear the 6-COOH group in 100% purity. The optical rotatory dispersion (ORD) spectra indicated that the obtained CurCOOH behaves as a water-soluble single-strand in various pH aqueous media. This advantage has allowed us to use CurCOOH as a polymeric host to form various macromolecular complexes. For example, complexation of CurCOOH with single-walled carbon nanotubes (SWNTs) resulted in a water-soluble one-dimensional architecture, which formed a dispersion in aqueous solution that was stable for several months, and much more stable than SWNTs complexes of the similar negatively-charged polyacrylic acid (PAA) and polymethacrylic acid (PMAA). It was shown that in the complex, SWNTs are effectively wrapped by a small amount of CurCOOH, enabling them to avoid electrostatic repulsion. This pH-responsive CurCOOH formed a very stable complex with cationic water-soluble polythiophenes (PT-1), which was stabilized not only by the hydrophobic interaction but also by the electrostatic attraction between trimethylammonium cations in PT-1 and dissociated anionic COO(-) groups in CurCOOH. The included PT-1 became CD-active only in the neutral to basic pH region, and the positive Cotton effect suggested that the conjugated main chain is twisted in the right-handed direction. We also found that CurCOOH can interact with polycytidylic acid (poly(C)) only under high NaCl concentrations, the binding and release of which could be controlled by a change in the salt concentration. We believe, therefore, that Cur

A core hSSB1–INTS complex participates in the DNA damage response

OpenAIRE

Zhang, Feng; Ma, Teng; Yu, Xiaochun

2013-01-01

Human single-stranded DNA-binding protein 1 (hSSB1) plays an important role in the DNA damage response and the maintenance of genomic stability. It has been shown that the core hSSB1 complex contains hSSB1, INTS3 and C9orf80. Using protein affinity purification, we have identified integrator complex subunit 6 (INTS6) as a major subunit of the core hSSB1 complex. INTS6 forms a stable complex with INTS3 and hSSB1 both in vitro and in vivo. In this complex, INTS6 directly interacts with INTS3. I...

Characterization of the adenoassociated virus Rep protein complex formed on the viral origin of DNA replication

International Nuclear Information System (INIS)

Li Zengi; Brister, J. Rodney; Im, Dong-Soo; Muzyczka, Nicholas

2003-01-01

Interaction between the adenoassociated virus (AAV) replication proteins, Rep68 and 78, and the viral terminal repeats (TRs) is mediated by a DNA sequence termed the Rep-binding element (RBE). This element is necessary for Rep-mediated unwinding of duplex DNA substrates, directs Rep catalyzed cleavage of the AAV origin of DNA replication, and is required for viral transcription and proviral integration. Six discrete Rep complexes with the AAV TR substrates have been observed in vitro, and cross-linking studies suggest these complexes contain one to six molecules of Rep. However, the functional relationship between Rep oligomerization and biochemical activity is unclear. Here we have characterized Rep complexes that form on the AAV TR. Both Rep68 and Rep78 appear to form the same six complexes with the AAV TR, and ATP seems to stimulate formation of specific, higher order complexes. When the sizes of these Rep complexes were estimated on native polyacrylamide gels, the four slower migrating complexes were larger than predicted by an amount equivalent to one or two TRs. To resolve this discrepancy, the molar ratio of protein and DNA was calculated for the three largest complexes. Data from these experiments indicated that the larger complexes included multiple TRs in addition to multiple Rep molecules and that the Rep-to-TR ratio was approximately 2. The two largest complexes were also associated with increased Rep-mediated, origin cleavage activity. Finally, we characterized a second, Rep-mediated cleavage event that occurs adjacent to the normal nicking site, but on the opposite strand. This second site nicking event effectively results in double-stranded DNA cleavage at the normal nicking site

Charge transfer complex studies between some non-steroidal anti-inflammatory drugs and π-electron acceptors

Science.gov (United States)

Duymus, Hulya; Arslan, Mustafa; Kucukislamoglu, Mustafa; Zengin, Mustafa

2006-12-01

Charge transfer (CT) complexes of some non-steroidal anti-inflammatory drugs, naproxen and etodolac which are electron donors with some π-acceptors, such as tetracyanoethylene (TCNE), 2,3-dichloro-5,6-dicyano- p-benzoquinone (DDQ), p-chloranil ( p-CHL), have been investigated spectrophotometrically in chloroform at 21 °C. The coloured products are measured spectrophotometrically at different wavelength depending on the electronic transition between donors and acceptors. Beer's law is obeyed and colours were produced in non-aqueous media. All complexes were stable at least 2 h except for etodolac with DDQ stable for 5 min. The equilibrium constants of the CT complexes were determined by the Benesi-Hildebrand equation. The thermodynamic parameters Δ H, Δ S, Δ G° were calculated by Van't Hoff equation. Stochiometries of the complexes formed between donors and acceptors were defined by the Job's method of the continuous variation and found in 1:1 complexation with donor and acceptor at the maximum absorption bands in all cases.

Oligomeric adiponectin forms and their complexes in the blood of healthy donors and patients with type 2 diabetes mellitus.

Science.gov (United States)

Kogan, Alexander E; Filatov, Vladimir L; Kolosova, Olga V; Katrukha, Ivan A; Mironova, Ekaterina V; Zhuravleva, Natalya S; Nagibin, Oleg A; Kara, Andrei N; Bereznikova, Anastasiya V; Katrukha, Alexey G

2013-01-01

Adiponectin (Adn) is a protein that circulates in the blood in several oligomeric forms, namely low-, medium-, and high-molecular-weight forms. Adn may serve as a risk factor for type 2 diabetes mellitus (T2DM). The aims of this work were (1) to produce monoclonal antibodies (MAbs) specific to different Adn oligomeric forms, (2) to design immunoassays suitable for measuring the Adn forms present in human blood, and (3) to investigate the changes in Adn forms that occur in patients with T2DM. Gel filtration, fluoroimmunoassays, and Western blotting were utilized as major techniques in this study. MAbs recognizing various oligomeric forms of Adn were obtained. Complexes between Adn and complement component C1q and between the low molecular weight form of Adn and albumin were described in human blood. A decrease in the total Adn and Adn-albumin complex levels in the blood of patients with T2DM and no difference in the levels of the Adn-C1q complex in comparison with healthy volunteers were demonstrated. An Adn94-Adn63 fluoroimmunoassay was selected as the technique that most accurately measured the mass ratio of Adn oligomers in blood samples, and an Adn214-Adn27 assay that measured the low-molecular-weight form of Adn only.

Activity of Topotecan toward the DNA/Topoisomerase I Complex: A Theoretical Rationalization.

Science.gov (United States)

Bali, Semiha Kevser; Marion, Antoine; Ugur, Ilke; Dikmenli, Ayse Kumru; Catak, Saron; Aviyente, Viktorya

2018-03-06

Topotecan (TPT) is a nontoxic anticancer drug characterized by a pH-dependent lactone/carboxyl equilibrium. TPT acts on the covalently bonded DNA/topoisomerase I (DNA/TopoI) complex by intercalating between two DNA bases at the active site. This turns TopoI into a DNA-damaging agent and inhibits supercoil relaxation. Although only the lactone form of the drug is active and effectively inhibits TopoI, both forms have been co-crystallized at the same location within the DNA/TopoI complex. To gain further insights into the pH-dependent activity of TPT, the differences between two TPT:DNA/TopoI complexes presenting either the lactone (acidic pH) or the carboxyl (basic pH) form of TPT were studied by means of molecular dynamic simulations, quantum mechanical/molecular mechanical calculations, and topological analysis. We identified two specific amino acids that have a direct relationship with the activity of the drug, i.e., lysine 532 (K532) and asparagine 722 (N722). K532 forms a stable hydrogen bond bridge between TPT and DNA only when the drug is in its active lactone form. The presence of the active drug triggers the formation of an additional stable interaction between DNA and protein residues, where N722 acts as a bridge between the two fragments, thus increasing the binding affinity of DNA for TopoI and further slowing the release of DNA. Overall, our results provide a clear understanding of the activity of the TPT-like class of molecules and can help in the future design of new anticancer drugs targeting topoisomerase enzymes.

Cation and anion dependence of stable geometries and stabilization energies of alkali metal cation complexes with FSA(-), FTA(-), and TFSA(-) anions: relationship with physicochemical properties of molten salts.

Science.gov (United States)

Tsuzuki, Seiji; Kubota, Keigo; Matsumoto, Hajime

2013-12-19

Stable geometries and stabilization energies (Eform) of the alkali metal complexes with bis(fluorosulfonyl)amide, (fluorosulfonyl)(trifluoromethylslufonyl)amide and bis(trifluoromethylsulfonyl)amide (FSA(-), FTA(-) and TFSA(-)) were studied by ab initio molecular orbital calculations. The FSA(-) complexes prefer the bidentate structures in which two oxygen atoms of two SO2 groups have contact with the metal cation. The FTA(-) and TFSA(-) complexes with Li(+) and Na(+) prefer the bidentate structures, while the FTA(-) and TFSA(-) complexes with Cs(+) prefer tridentate structures in which the metal cation has contact with two oxygen atoms of an SO2 group and one oxygen atom of another SO2 group. The two structures are nearly isoenergetic in the FTA(-) and TFSA(-) complexes with K(+) and Rb(+). The magnitude of Eform depends on the alkali metal cation significantly. The Eform calculated for the most stable TFSA(-) complexes with Li(+), Na(+), K(+), Rb(+) and Cs(+) cations at the MP2/6-311G** level are -137.2, -110.5, -101.1, -89.6, and -84.1 kcal/mol, respectively. The viscosity and ionic conductivity of the alkali TFSA molten salts have strong correlation with the magnitude of the attraction. The viscosity increases and the ionic conductivity decreases with the increase of the attraction. The melting points of the alkali TFSA and alkali BETA molten salts also have correlation with the magnitude of the Eform, which strongly suggests that the magnitude of the attraction play important roles in determining the melting points of these molten salts. The anion dependence of the Eform calculated for the complexes is small (less than 2.9 kcal/mol). This shows that the magnitude of the attraction is not the cause of the low melting points of alkali FTA molten salts compared with those of corresponding alkali TFSA molten salts. The electrostatic interactions are the major source of the attraction in the complexes. The electrostatic energies for the most stable TFSA

Structure of β- N-dimethylamino-4-dodecyloxypropiophenone complexes with di- and polycarboxylic acids

Science.gov (United States)

Lebedeva, Tamara L.; Shandryuk, George A.; Sycheva, Tatyana I.; Bezborodov, Vladimir S.; Talroze, Raissa V.; Platé, Nicolai A.

1995-07-01

The type of bonds responsible for the complexation of di- and polyacids with the tertiary amine β- N-dimethylamino-4-dodecyloxypropiophenone is studied by means of FTIR spectroscopy. The complexes are shown to be stable due to strong H-bonding with partial charge transfer. The characteristic composition for complexes of polyacrylic, polymethacrylic and malonic acids is calculated as 2:1 (number of carboxylic groups per number of amine molecules) whereas glutaric acid forms complexes of different composition including 1:1. The characteristic composition results from the structure of the initial acid. The structures of both the characteristic complex and "excess" acid are also discussed.

Stability of the spherical form of nuclei

International Nuclear Information System (INIS)

Sabry, A.A.

1976-08-01

An extension of the mass formula for a spherical nucleus in the drop model to include a largely deformed nucleus of different forms is investigated. It is found that although the spherical form is stable under small deformations from equilibrium, there exists for heavier nuclei another more favourable stable form, which can be approximated by two, or three touching prolate ellipsoids of revolution

Formation of aqueous complexes of metal ions formed during the reprocessing of nuclear fuels with ortho-phenanthroline and dibutylphosphate

International Nuclear Information System (INIS)

Musikas, C.; Le Marois, G.; Racinoux, J.

1979-01-01

In this work the formation of aqueous complexes of metalions (lanthanides, actinides) was investigated that occurs during reprocessing of nuclear combustibles with ortho-phenanthroline and dibutylphosphate. Complexes with different ligand numbers and solubility are formed. Cationic and anionic forms according to the DBP concentration in the extraction solution. Acid-base titrations, absorption spectra and solubility determinations were used for the characterization. (RB) [de

Method for recovering or recirculating stable nitroxide radicals

NARCIS (Netherlands)

Heeres, Andre; Van Doren, Hendrik Arend; Bleeker, Ido Pieter; Gotlieb, Kornelis Fester.

1996-01-01

The invention relates fo a method for recovering stable nitroxide radicals, wherein at least a part of a reaction mixt. consisting of a soln. or suspension, or a filtrate or supernatant of a suspension, in which stable nitroxide radicals are present in non-solid form, is subjected to an azeotropic

Formation of molecular complexes of salicylic acid, acetylsalicylic acid, and methyl salicylate in a mixture of supercritical carbon dioxide with a polar cosolvent

Science.gov (United States)

Petrenko, V. E.; Antipova, M. L.; Gurina, D. L.; Odintsova, E. G.

2015-08-01

The solvate structures formed by salicylic acid, acetylsalicylic acid, and methyl salicylate in supercritical (SC) carbon dioxide with a polar cosolvent (methanol, 0.03 mole fractions) at a density of 0.7 g/cm3 and a temperature of 318 K were studied by the molecular dynamics method. Salicylic and acetylsalicylic acids were found to form highly stable hydrogen-bonded complexes with methanol via the hydrogen atom of the carboxyl group. For methyl salicylate in which the carboxyl hydrogen is substituted by a methyl radical, the formation of stable hydrogen bonds with methanol was not revealed. The contribution of other functional groups of the solute to the interactions with the cosolvent was much smaller. An analysis of correlations between the obtained data and the literature data on the cosolvent effect on the solubility of the compounds in SC CO2 showed that the dissolving ability of SC CO2 with respect to a polar organic substance in the presence of a cosolvent increased only when stable hydrogen-bonded complexes are formed between this substance and the cosolvent.

Structural basis of the pH-dependent assembly of a botulinum neurotoxin complex.

Science.gov (United States)

Matsui, Tsutomu; Gu, Shenyan; Lam, Kwok-Ho; Carter, Lester G; Rummel, Andreas; Mathews, Irimpan I; Jin, Rongsheng

2014-11-11

Botulinum neurotoxins (BoNTs) are among the most poisonous biological substances known. They assemble with non-toxic non-hemagglutinin (NTNHA) protein to form the minimally functional progenitor toxin complexes (M-PTC), which protects BoNT in the gastrointestinal tract and releases it upon entry into the circulation. Here we provide molecular insight into the assembly between BoNT/A and NTNHA-A using small-angle X-ray scattering. We found that the free form BoNT/A maintains a pH-independent conformation with limited domain flexibility. Intriguingly, the free form NTNHA-A adopts pH-dependent conformational changes due to a torsional motion of its C-terminal domain. Once forming a complex at acidic pH, they each adopt a stable conformation that is similar to that observed in the crystal structure of the M-PTC. Our results suggest that assembly of the M-PTC depends on the environmental pH and that the complex form of BoNT/A is induced by interacting with NTNHA-A at acidic pH. Copyright © 2014 Elsevier Ltd. All rights reserved.

Synthesis, characterization, DFT calculations and antibacterial activity of palladium(II) cyanide complexes with thioamides

Science.gov (United States)

Ahmad, Saeed; Nadeem, Shafqat; Anwar, Aneela; Hameed, Abdul; Tirmizi, Syed Ahmed; Zierkiewicz, Wiktor; Abbas, Azhar; Isab, Anvarhusein A.; Alotaibi, Mshari A.

2017-08-01

Palladium(II) cyanide complexes of thioamides (or thiones) having the general formula PdL2(CN)2, where L = Thiourea (Tu), Methylthiourea (Metu), N,N‧-Dimethylthiourea (Dmtu), Tetramethylthiourea (Tmtu), 2-Mercaptopyridine (Mpy) and 2-Mercaptopyrimidine (Mpm) were prepared by reacting K2[PdCl4] with potassium cyanide and thioamides in the molar ratio of 1:2:2. The complexes were characterized by elemental analysis, thermal and spectroscopic methods (IR, 1H and 13C NMR). The structures of three of the complexes were predicted by DFT calculations. The appearance of a band around 2100 cm-1 in IR and resonances around 120-130 ppm in the 13C NMR spectra indicated the coordination of cyanide to palladium(II). More than one resonances were observed for CN- carbon atoms in 13C NMR indicating the existence of equilibrium between different species in solution. DFT calculations revealed that in the case of the palladium(II) complex of Tmtu, the ionic dinuclear [Pd(Tmtu)4][Pd(CN)4] form was more stable than the dimer of mononuclear complex [Pd(Tmtu)2(CN)2] by 0.91 kcal mol-1, while for the complexes of Tu or Mpy ligands, the nonionic [Pd(L)2(CN)2] forms were more stable than the corresponding [Pd(L)4][Pd(CN)4] complexes by 1.26 and 6.49 kcal mol-1 for L = Tu and Mpy, respectively. The complexes were screened for antibacterial effects and some of them showed significant activities against both gram positive as well as gram negative bacteria.

EXAFS investigation of uranium(6) complexes formed at Acidithiobacillus ferro oxidans types

International Nuclear Information System (INIS)

Merroun, M.; Reich, T.; Hennig, Ch.; Selenska-Pobell, S.

2002-01-01

Mining activities have brought excessive amounts of uranium into the environment. In uranium deposits a number of acidophilic chemo-litho-autotrophic bacteria have been identified which are able to oxidize sulphide minerals, elemental sulphur, ferrous iron and also (in the presence of uranium mineral) U(IV). In particular, the interaction of one representative of the group Acidithiobacillus ferro oxidans (new designation of Thiobacillus ferro oxidans) with uranium has been investigated. Uranium(VI) complex formations at the surfaces of Acidithiobacillus ferro oxidans were studied using uranium L III -edge extended X-ray absorption fine structure (EXAFS) spectroscopy. In all samples uranium is co-ordinated by two axial oxygen atoms (O ax ) at a distance of 1.77-1.78 angstrom. The average distance between uranium and the equatorial oxygen atoms (O eq ) is 2.35 angstrom. The co-ordination number for O eq is 5-6. In comparison to the uranium crystal structure data, the U-O eq distance indicates a co-ordination number of the equatorial oxygen of 5. Within the experimental error, there are no differences in the U-O bond distances between samples from the three types of A. ferro oxidans investigated. The fit to the EXAFS data of samples measured as wet pastes gave the same results as for dried samples. No significant structural differences were observed for the uranium complexes formed by the eco-types of A. ferro oxidans. However, the EXAFS spectra do indicate a formation of uranium complexes which are different from those formed by Bacilli where the bond length of 2.28 angstrom indicates a co-ordination number of 4 for the equatorial oxygen atoms. (authors)

Identification of a small TAF complex and its role in the assembly of TAF-containing complexes.

Science.gov (United States)

Demény, Màté A; Soutoglou, Evi; Nagy, Zita; Scheer, Elisabeth; Jànoshàzi, Agnes; Richardot, Magalie; Argentini, Manuela; Kessler, Pascal; Tora, Laszlo

2007-03-21

TFIID plays a role in nucleating RNA polymerase II preinitiation complex assembly on protein-coding genes. TFIID is a multisubunit complex comprised of the TATA box binding protein (TBP) and 14 TBP-associated factors (TAFs). Another class of multiprotein transcriptional regulatory complexes having histone acetyl transferase (HAT) activity, and containing TAFs, includes TFTC, STAGA and the PCAF/GCN5 complex. Looking for as yet undiscovered subunits by a proteomic approach, we had identified TAF8 and SPT7L in human TFTC preparations. Subsequently, however, we demonstrated that TAF8 was not a stable component of TFTC, but that it is present in a small TAF complex (SMAT), containing TAF8, TAF10 and SPT7L, that co-purified with TFTC. Thus, TAF8 is a subunit of both TFIID and SMAT. The latter has to be involved in a pathway of complex formation distinct from the other known TAF complexes, since these three histone fold (HF)-containing proteins (TAF8, TAF10 and SPT7L) can never be found together either in TFIID or in STAGA/TFTC HAT complexes. Here we show that TAF8 is absolutely necessary for the integration of TAF10 in a higher order TFIID core complex containing seven TAFs. TAF8 forms a heterodimer with TAF10 through its HF and proline rich domains, and also interacts with SPT7L through its C-terminal region, and the three proteins form a complex in vitro and in vivo. Thus, the TAF8-TAF10 and TAF10-SPT7L HF pairs, and also the SMAT complex, seem to be important regulators of the composition of different TFIID and/or STAGA/TFTC complexes in the nucleus and consequently may play a role in gene regulation.

Selenite and tellurite form mixed seleno- and tellurotrisulfides with CstR from Staphylococcus aureus

OpenAIRE

Luebke, Justin L.; Arnold, Randy J.; Giedroc, David P.

2013-01-01

Staphylococcus aureus CstR (CsoR-like sulfur transferase repressor) is a member of the CsoR family of transition metal sensing metalloregulatory proteins. Unlike CsoR, CstR does not form a stable complex with transition metals but instead reacts with sulfite to form a mixture of di- and trisulfide species, CstR2(RS-SR′) and CstR2(RS-S-SR′)n, n = 1 or 2, respectively. Here, we investigate if CstR performs similar chemistry with related chalcogen oxyanions selenite and tellurite. In this work w...

Architecture of Amylose Supramolecules in Form of Inclusion Complexes by Phosphorylase-Catalyzed Enzymatic Polymerization

Directory of Open Access Journals (Sweden)

Jun-ichi Kadokawa

2013-07-01

Full Text Available This paper reviews the architecture of amylose supramolecules in form of inclusion complexes with synthetic polymers by phosphorylase-catalyzed enzymatic polymerization. Amylose is known to be synthesized by enzymatic polymerization using α-d-glucose 1-phosphate as a monomer, by phosphorylase catalysis. When the phosphorylase-catalyzed enzymatic polymerization was conducted in the presence of various hydrophobic polymers, such as polyethers, polyesters, poly(ester-ether, and polycarbonates as a guest polymer, such inclusion supramolecules were formed by the hydrophobic interaction in the progress of polymerization. Because the representation of propagation in the polymerization is similar to the way that a vine of a plant grows, twining around a rod, this polymerization method for the formation of amylose-polymer inclusion complexes was proposed to be named “vine-twining polymerization”. To yield an inclusion complex from a strongly hydrophobic polyester, the parallel enzymatic polymerization system was extensively developed. The author found that amylose selectively included one side of the guest polymer from a mixture of two resemblant guest polymers, as well as a specific range in molecular weights of the guest polymers poly(tetrahydrofuran (PTHF in the vine-twining polymerization. Selective inclusion behavior of amylose toward stereoisomers of chiral polyesters, poly(lactides, also appeared in the vine-twining polymerization.

Stable X chromosome inactivation involves the PRC1 Polycomb complex and requires histone MACROH2A1 and the CULLIN3/SPOP ubiquitin E3 ligase

DEFF Research Database (Denmark)

Hernández-Muñoz, Inmaculada; Lund, Anders H; van der Stoop, Petra

2005-01-01

X inactivation involves the stable silencing of one of the two X chromosomes in XX female mammals. Initiation of this process occurs during early development and involves Xist (X-inactive-specific transcript) RNA coating and the recruitment of Polycomb repressive complex (PRC) 2 and PRC1 proteins...

Thermally stable sintered porous metal articles

International Nuclear Information System (INIS)

Gombach, A.L.; Thellmann, E.L.

1980-01-01

A sintered porous metal article is provided which is essentially thermally stable at elevated temperatures. In addition, a method for producing such an article is also provided which method comprises preparing a blend of base metal particles and active dispersoid particles, forming the mixture into an article of the desired shape, and heating the so-formed article at sintering temperatures

Method for forming thermally stable nanoparticles on supports

Science.gov (United States)

Roldan Cuenya, Beatriz; Naitabdi, Ahmed R.; Behafarid, Farzad

2013-08-20

An inverse micelle-based method for forming nanoparticles on supports includes dissolving a polymeric material in a solvent to provide a micelle solution. A nanoparticle source is dissolved in the micelle solution. A plurality of micelles having a nanoparticle in their core and an outer polymeric coating layer are formed in the micelle solution. The micelles are applied to a support. The polymeric coating layer is then removed from the micelles to expose the nanoparticles. A supported catalyst includes a nanocrystalline powder, thin film, or single crystal support. Metal nanoparticles having a median size from 0.5 nm to 25 nm, a size distribution having a standard deviation .ltoreq.0.1 of their median size are on or embedded in the support. The plurality of metal nanoparticles are dispersed and in a periodic arrangement. The metal nanoparticles maintain their periodic arrangement and size distribution following heat treatments of at least 1,000.degree. C.

(Pyridine)(tetrahydroborato)zinc complex, (Zn(BH{sub 4}){sub 2}(py)), as a new stable, efficient and chemoselective reducing agent for reduction of carbonyl compounds

Energy Technology Data Exchange (ETDEWEB)

Zeynizadeh, Behzad; Faraji, Fariba [Urima Univ., Urima (Iran, Islamic Republic of)

2003-04-01

(Pyridine)(tetrahydroborato)zinc complex, (Zn(BH{sub 4}){sub 2}(py)), as a stable white solid, was prepared quantitatively by complexation of an equimolar amount of zinc tetrahydroborate and pyridine at room temperature. This reagent can easily reduce variety of carbonyl compounds such as aldehydes, ketones, acyloins, {alpha}-diketones and {alpha},{beta}-unsaturated carbonyl compounds to their corresponding alcohols in good to excellent yields. Reduction reactions were performed in ether or THF at room temperature or under reflux conditions. In addition, the chemoselective reduction of aldehydes over ketones was accomplished successfully with this reducing agent.

Development of indirect spectrophotometric method for quantification of cephalexin in pure form and commercial formulation using complexation reaction

International Nuclear Information System (INIS)

Khan, M.N.; Hussain, R.; Kalsoom, S.; Saadiq, M.

2016-01-01

A simple, accurate and indirect spectrophotometric method was developed for the quantification of cephalexin in pure form and pharmaceutical products using complexation reaction. The developed method is based on the oxidation of the cephalexin with Fe/sup 3+/ in acidic medium. Then 1, 10- phenanthroline reacts with Fe/sup 2+/ and a red colored complex was formed. The absorbance of the complex was measured at 510 nm by spectrophotometer. Different experimental parameters affecting the complexation reactions were studied and optimized. Beer law was obeyed in the concentration range 0.4 -10 micro gmL/sup -1/ with a good correlation of 0.992. The limit of detection and limit of quantification were found to be 0.065 micro gmL/sup -1/ and 0.218 micro gmL/sup -1/ , respectively. The method have good reproducibility with a relative standard deviation of 6.26 percent (n = 6). The method was successfully applied for the determination of cephalexin in bulk powder and commercial formulation. Percent recoveries were found to range from 95.47 to 103.87 percent for the pure form and 98.62 to 103.35 percent for commercial formulations. (author)

PUBLIC-PRIVATE PARTNERSHIP AS A FORM OF DEVELOPMENT OF THE AGRO-INDUSTRIAL COMPLEX OF THE RUSSIAN FEDERATION

Directory of Open Access Journals (Sweden)

Albert G. Mnatsakanyan

2018-03-01

Full Text Available The article examines the current state of public-private partnership in the agro-industrial complex of the Russian Federation, provides a refined definition of public-private partnership. The authors give a full determination of the public-private partnership in Russia. The structure of existing agro-industrial clusters on the territory of the Russian Federation is studied. The article contains characteristics of the agro-industrial complex, which affect the low involvement of private investment. The state of the agro-industrial complex is analyzed, the main problems of applying public-private partnerships in the agro-industrial complex are revealed, and recommendations for improving the mechanism for applying public-private partnerships are given. The study highlights the main advantages of using the mechanism of public-private partnership, analyzes trends and prospects for using this mechanism. The scientific works of domestic and foreign scientists in the field of public-private partnership and agro-industrial complex became the methodological basis of scientific research. System analysis, a set of methods of economic and statistical analysis, methods of synthesis and analysis of economic information, a comparative method were used as the methods of research. The article concludes that it is necessary to use the mechanisms of public-private partnership in the agro-industrial complex of the Russian Federation regarding the need for significant investments in the industry to maintain competitiveness. It is necessary to use such forms of public-private partnership that will use financial and administrative resources of state authorities even at the initial stage of the project, and later private business will repay the share of the invested state funds, up to the privatization of the property complex. This form of cooperation will help reduce the risks of private investors and attract new investments in the agro-industrial complex of the Russian

Ageing as a price of cooperation and complexity: self-organization of complex systems causes the gradual deterioration of constituent networks.

Science.gov (United States)

Kiss, Huba J M; Mihalik, Agoston; Nánási, Tibor; Ory, Bálint; Spiró, Zoltán; Soti, Csaba; Csermely, Peter

2009-06-01

The network concept is increasingly used for the description of complex systems. Here, we summarize key aspects of the evolvability and robustness of the hierarchical network set of macromolecules, cells, organisms and ecosystems. Listing the costs and benefits of cooperation as a necessary behaviour to build this network hierarchy, we outline the major hypothesis of the paper: the emergence of hierarchical complexity needs cooperation leading to the ageing (i.e. gradual deterioration) of the constituent networks. A stable environment develops cooperation leading to over-optimization, and forming an 'always-old' network, which accumulates damage, and dies in an apoptosis-like process. A rapidly changing environment develops competition forming a 'forever-young' network, which may suffer an occasional over-perturbation exhausting system resources, and causing death in a necrosis-like process. Giving a number of examples we demonstrate how cooperation evokes the gradual accumulation of damage typical to ageing. Finally, we show how various forms of cooperation and consequent ageing emerge as key elements in all major steps of evolution from the formation of protocells to the establishment of the globalized, modern human society.

NMR Investigation of the complexation of (S-2-isopropyl- 1-(o-nitrophenylsulfonylaziridine with -cyclodextrin

Directory of Open Access Journals (Sweden)

Mohamed Z. Sliman

2014-07-01

Full Text Available Aziridines are known to undergo hydrolysis in the presence of cyclodextrins, whereas the latter are largely investigated as potential vectors of biologically active compounds. Despite this easy cyclodextrin-induced cleavage of aziridines in aqueous medium, it was of interest to find out a model aziridine derivative that would be sufficiently water-stable and form a stable complex with b-cyclodextrin in aqueous medium, so that it could be used as a reference in future formulations or vectorization work. Among compounds we have investigated, we found out that only (S-2-isopropyl-1-(o-nitrophenylsulfonylaziridine complied with the above-mentioned solubility and stability requirements. NMR studies of the inclusion complex of this derivative with b-cyclodextrin provided useful parameters related to the stoichiometry of the complex and the association constant Ka. The geometry of the complex was assessed by 2D-ROESY experiments, suggesting a deep insertion of the aziridine into the cavity of b-cyclodextrin.

ESR study of /sup 99/Tc(II) complex formed by reduction of ammonium pertechnetate with ascorbic acid in concentrated hydrochloric acid

Energy Technology Data Exchange (ETDEWEB)

Kudo, T; Tsuchihashi, N; Ogata, T

1987-07-30

Paramagnetic /sup 99/Tc complex formed by the reduction of ammonium pertechnetate by ascorbic acid with excess sodium nitrite in concentrated hydrochloric acid was investigated by ESR technique. This complex had total electron spin S=1/2 and the obtained ESR parameters are 2.032, 2.043; and 264, 108 gauss, respectively. It was concluded that the formed species was low spin /sup 99/Tc(II) complex. (author) 13 refs.

Behaviors and chemical forms of radionuclides in seawater

International Nuclear Information System (INIS)

Honda, Yoshihide

1981-01-01

Although the radionuclides introduced into the marine environment from various sources and routes are finally distributed among the components of the marine ecosystem, the residence time is one of the most useful measures of the reactivity of an element in the oceanic chemical system. Heavy metals such as Mn, Fe, Co and Zn which have shorter residence times, reveal more complicated behaviours in relation to marine radioecological interest than alkaline earth element such as Sr which has a longer residence time. The possible physico-chemical forms of radionuclides in the oceans are usually classified into three categories, that is, species in true solution, colloidal species, and particulate forms. The modeling to study the dispersion of radionuclides introduced into the marine environment can be approached with the aid of the knowledge of behaviors of their stable counterparts in seawater. The different physico-chemical forms between stable and radioactive nuclides in seawater may cause different biological concentration of the element. To realize the chemical speciation of radionuclides in the marine environment, it is also important in thermodynamical calculation to consider heterogeneous interfaces where cause raising the concentration of reactants in seawater, especially in the coastal waters. In the discussion on the primary factors that can affect the elemental distribution in the marine environment, primary productivity and bacterial activity are emphasized for the transformation of physicochemical states of radionuclides in the marine environment. Finally, the radioecological differences between radiocobalt in organic complexed and ionic forms were demonstrated in the experiments on the uptake and elimination of radiocobalt by mussels. (J.P.N.)

Complexes of uranyl nitrate with 2,6-pyridinedicarboxamides: synthesis, crystal structure, and DFT study

Energy Technology Data Exchange (ETDEWEB)

Alyapyshev, Mikhail; Babain, Vasiliy [ITMO University, 49, Kronverksky pr., 197101, St. Petersburg (Russian Federation); ThreeArc Mining Ltd., 5, Stary Tolmachevskiy per., 115184, Moscow (Russian Federation); Tkachenko, Lyudmila; Lumpov, Alexander [Khlopin Radium Institute, 28, 2nd Murinskiy pr., 194021, St. Petersburg (Russian Federation); Gurzhiy, Vladislav; Zolotarev, Andrey; Dar' in, Dmitriy [St. Petersburg State University, 7-9, Universitetskaya nab., 199034, St. Petersburg (Russian Federation); Ustynyuk, Yuriy; Gloriozov, Igor [M.V. Lomonosov Moscow State University, 119991, Moscow (Russian Federation); Paulenova, Alena [Department of Nuclear Engineering, Oregon State University, Corvallis, OR (United States)

2017-05-04

Two complexes of uranyl nitrate with N,N,N',N'-tetrabutyl-2,6-pyridinedicarboxamide (TBuDPA) and N,N'-diethyl-N,N'-diphenyl-2,6-pyridinedicarboxamide (EtPhDPA) were synthesized and studied. The complex of tetraalkyl-2,6-pyridinedicarboxamide with metal nitrate was synthesized for the first time. XRD analysis revealed the different type of complexation: a 1:1 metal:ligand complex for EtPhDPA and complex with polymeric structure for TBuDPA. The quantum chemical calculations (DFT) confirm that both ligands form the most stable complexes that match the minimal values pre-organization energy of the ligands. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

The Optimal Conditions for Form-Focused Instruction: Method, Target Complexity, and Types of Knowledge

Science.gov (United States)

Kim, Jeong-eun

2012-01-01

This dissertation investigates optimal conditions for form-focused instruction (FFI) by considering effects of internal (i.e., timing and types of FFI) and external (i.e., complexity and familiarity) variables of FFI when it is offered within a primarily meaning-focused context of adult second language (L2) learning. Ninety-two Korean-speaking…

VHL type 2B mutations retain VBC complex form and function.

Directory of Open Access Journals (Sweden)

Kathryn E Hacker

Full Text Available von Hippel-Lindau disease is characterized by a spectrum of hypervascular tumors, including renal cell carcinoma, hemangioblastoma, and pheochromocytoma, which occur with VHL genotype-specific differences in penetrance. VHL loss causes a failure to regulate the hypoxia inducible factors (HIF-1alpha and HIF-2alpha, resulting in accumulation of both factors to high levels. Although HIF dysregulation is critical to VHL disease-associated renal tumorigenesis, increasing evidence points toward gradations of HIF dysregulation contributing to the degree of predisposition to renal cell carcinoma and other manifestations of the disease.This investigation examined the ability of disease-specific VHL missense mutations to support the assembly of the VBC complex and to promote the ubiquitylation of HIF. Our interaction analysis supported previous observations that VHL Type 2B mutations disrupt the interaction between pVHL and Elongin C but maintain partial regulation of HIF. We additionally demonstrated that Type 2B mutant pVHL forms a remnant VBC complex containing the active members ROC1 and Cullin-2 which retains the ability to ubiquitylate HIF-1alpha.Our results suggest that subtypes of VHL mutations support an intermediate level of HIF regulation via a remnant VBC complex. These findings provide a mechanism for the graded HIF dysregulation and genetic predisposition for cancer development in VHL disease.

Stable isotope views on ecosystem function: challenging or challenged?

Science.gov (United States)

Resco, Víctor; Querejeta, José I; Ogle, Kiona; Voltas, Jordi; Sebastià, Maria-Teresa; Serrano-Ortiz, Penélope; Linares, Juan C; Moreno-Gutiérrez, Cristina; Herrero, Asier; Carreira, José A; Torres-Cañabate, Patricia; Valladares, Fernando

2010-06-23

Stable isotopes and their potential for detecting various and complex ecosystem processes are attracting an increasing number of scientists. Progress is challenging, particularly under global change scenarios, but some established views have been challenged. The IX meeting of the Spanish Association of Terrestrial Ecology (AAET, Ubeda, 18-22 October 2009) hosted a symposium on the ecology of stable isotopes where the linear mixing model approach of partitioning sinks and sources of carbon and water fluxes within an ecosystem was challenged, and new applications of stable isotopes for the study of plant interactions were evaluated. Discussion was also centred on the need for networks that monitor ecological processes using stable isotopes and key ideas for fostering future research with isotopes.

Mathematical Models to Determine Stable Behavior of Complex Systems

Science.gov (United States)

Sumin, V. I.; Dushkin, A. V.; Smolentseva, T. E.

2018-05-01

The paper analyzes a possibility to predict functioning of a complex dynamic system with a significant amount of circulating information and a large number of random factors impacting its functioning. Functioning of the complex dynamic system is described as a chaotic state, self-organized criticality and bifurcation. This problem may be resolved by modeling such systems as dynamic ones, without applying stochastic models and taking into account strange attractors.

Complex organic molecules toward low-mass and high-mass star forming regions

Science.gov (United States)

Favre, C.; Ceccarelli, C.; Lefloch, B.; Bergin, E.; Carvajal, M.; Brouillet, N.; Despois, D.; Jørgensen, J.; Kleiner, I.

2016-12-01

One of the most important questions in molecular astrophysics is how, when, and where complex organic molecules, COMs (≥ 6 atoms) are formed. In the Interstellar-Earth connection context, could this have a bearing on the origin of life on Earth? Formation mechanisms of COMs, which include potentially prebiotic molecules, are still debated and may include grain-mantle and/or gas-phase chemistry. Understanding the mechanisms that lead to the interstellar molecular complexification, along with the involved physicochemical processes, is mandatory to answer the above questions. In that context, active researches are ongoing in theory, laboratory experiment, chemical modeling and observations. Thanks to recent progress in radioastronomy instrumentation for both single-dish and millimeter array (e.g. Herschel, NOEMA, ALMA), new results have been obtained. I will review some notable results on the detection of COMs, including prebiotic molecules, towards star forming regions.

Two forms of acid alpha-D-mannosidase in monkey brain: evidence for the co-existence of high mannose and complex oligosaccharides in one form.

Science.gov (United States)

Mathur, R; Alvares, K; Balasubramanian, A S

1984-09-28

Lysosomal alpha-D-mannosidase of monkey brain existed in two forms. One form of mannosidase was bound to the Ricinus communis agglutinin120 (RCA1)-Sepharose and could be specifically eluted with lactose. The other form did not bind to the RCA1-Sepharose. Both forms of mannosidase could bind to a similar extent to the immobilized brain lysosomal receptor protein. Both the forms were purified to apparent homogeneity. Neutral sugar analysis by GLC showed the presence of glucose, mannose and galactose in the RCA1-Sepharose bindable mannosidase and glucose and mannose in the non-bindable mannosidase. Several other brain lysosomal hydrolases did not bind to the RCA1-Sepharose. The results suggested the existence of only high mannose oligosaccharides in the RCA1 non-bindable mannosidase and both high mannose and complex oligosaccharides in the bindable mannosidase.

Correlation of mitochondrial protein expression in complexes I to V with natural and induced forms of canine idiopathic dilated cardiomyopathy.

Science.gov (United States)

Lopes, Rosana; Solter, Philip F; Sisson, D David; Oyama, Mark A; Prosek, Robert

2006-06-01

To identify qualitative and quantitative differences in cardiac mitochondrial protein expression in complexes I to V between healthy dogs and dogs with natural or induced dilated cardiomyopathy (DCM). Left ventricle samples were obtained from 7 healthy dogs, 7 Doberman Pinschers with naturally occurring DCM, and 7 dogs with DCM induced by rapid right ventricular pacing. Fresh and frozen mitochondrial fractions were isolated from the left ventricular free wall and analyzed by 2-dimensional electrophoresis. Protein spots that increased or decreased in density by 2-fold or greater between groups were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry or quadrupole selecting, quadrupole collision cell, time-of-flight mass spectrometry. A total of 22 altered mitochondrial proteins were identified in complexes I to V. Ten and 12 were found in complex I and complexes II to V, respectively. Five were mitochondrial encoded, and 17 were nuclear encoded. Most altered mitochondrial proteins in tissue specimens from dogs with naturally occurring DCM were associated with complexes I and V, whereas in tissue specimens from dogs subjected to rapid ventricular pacing, complexes I and IV were more affected. In the experimentally induced form of DCM, only nuclear-encoded subunits were changed in complex I. In both disease groups, the 22-kd subunit was downregulated. Natural and induced forms of DCM resulted in altered mitochondrial protein expression in complexes I to V. However, subcellular differences between the experimental and naturally occurring forms of DCM may exist.

H2XP:OH2 Complexes: Hydrogen vs. Pnicogen Bonds

Directory of Open Access Journals (Sweden)

Ibon Alkorta

2016-02-01

Full Text Available A search of the Cambridge Structural Database (CSD was carried out for phosphine-water and arsine-water complexes in which water is either the proton donor in hydrogen-bonded complexes, or the electron-pair donor in pnicogen-bonded complexes. The range of experimental P-O distances in the phosphine complexes is consistent with the results of ab initio MP2/aug’-cc-pVTZ calculations carried out on complexes H2XP:OH2, for X = NC, F, Cl, CN, OH, CCH, H, and CH3. Only hydrogen-bonded complexes are found on the H2(CH3P:HOH and H3P:HOH potential surfaces, while only pnicogen-bonded complexes exist on H2(NCP:OH2, H2FP:OH2, H2(CNP:OH2, and H2(OHP:OH2 surfaces. Both hydrogen-bonded and pnicogen-bonded complexes are found on the H2ClP:OH2 and H2(CCHP:OH2 surfaces, with the pnicogen-bonded complexes more stable than the corresponding hydrogen-bonded complexes. The more electronegative substituents prefer to form pnicogen-bonded complexes, while the more electropositive substituents form hydrogen-bonded complexes. The H2XP:OH2 complexes are characterized in terms of their structures, binding energies, charge-transfer energies, and spin-spin coupling constants 2hJ(O-P, 1hJ(H-P, and 1J(O-H across hydrogen bonds, and 1pJ(P-O across pnicogen bonds.

Spectroscopic and first-principles calculation studies of the chemical forms of palladium ion in nitric acid solution for development of disposal of high-level radioactive nuclear wastes

Science.gov (United States)

Watanabe, Shinta; Sato, Toshikazu; Yoshida, Tomoko; Nakaya, Masato; Yoshino, Masahito; Nagasaki, Takanori; Inaba, Yusuke; Takeshita, Kenji; Onoe, Jun

2018-04-01

We have investigated the chemical forms of palladium (Pd) ion in nitric acid solution, using XAFS/UV-vis spectroscopic and first-principles methods in order to develop the disposal of high-level radioactive nuclear liquid wastes (HLLW: radioactive metal ions in 2 M nitric acid solution). The results of theoretical calculations and XAFS/UV-vis spectroscopy indicate that Pd is a divalent ion and forms a square-planar complex structure coordinated with four nitrate ions, [Pd(NO3)4]2-, in nitric acid solution. This complex structure is also thermodynamically predicted to be most stable among complexes [Pd(H2O)x(NO3)4-x]x-2 (x = 0-4). Since the overall feature of UV-vis spectra of the Pd complex was independent of nitric acid concentration in the range 1-6 M, the structure of the Pd complex remains unchanged in this range. Furthermore, we examined the influence of γ-ray radiation on the [Pd(NO3)4]2- complex, using UV-vis spectroscopy, and found that UV-vis spectra seemed not to be changed even after 1.0 MGy irradiation. This implies that the Pd complex structure will be still stable in actual HLLW. These findings obtained above are useful information to develop the vitrification processes for disposal of HLLW.

Preparation of phenacylchloride, morpholinophenacyl and N-Piperidinophenacyl oximes and study of their complexation with Copper (II) and Cobalt (II) ions

International Nuclear Information System (INIS)

Ali, Kamal Eldin Ahmed

1999-01-01

The aim of the present work is to prepare phenacyl chloride oxime and phenacyl of N-Piperidine and morpholine derivatives, and mainly to study their complexes with Cu(II) and Co(II) ions with objective ascertaining that one of these ligands can be used in quantitative extraction of these metal ions from the aqueous solution. Copper (II) salts form 1:1 complexes with the phenyacyl oximes of N-piperidine and morpholine and 1:2 complex with phenacyl chloride oxime. However, cobalt(II) salts form 1:2 complexes with phenacyl oxime of N-piperidine and morpholine but does not complex with phenacyl chloride oxime. The stoichiometry of these complexes were determined by UV/VIS spectrophotometry using the mole ratio, continuous variation and slope ratio methods.The stability constants of the five complexes were calculated from aberrances using Job's method. They showed that the copper (II) and cobalt (II) complexes with N-piperidinophenacy oxime are more stable than those with morpholinophenacyl oxime. Copper (II) complexes with any of these two ligands are more stable than those of cobalt (II). IR spectra of the complexes of copper (II) and cobalt (II) with phenacyl oxime of N-piperidine and morpholine show diminished peaks of hydrogen bonds between N and O atoms of the ligand. Specific extractabilities using amylalcohol of copper (II) complexes with the three ligands increase from PH4 to reach its maximum at PH8. The high value for N-piperidinophenacyl oxime ligand (96%-97%) indicates that, this ligand can be used as analytical reagent for the quantitative spectrophotometric determination of copper (II) salts in aqueous media. Cobalt (II) complexes were formed and extracted from solution only at PH6 (specific PH). The extractabilities ranging from 81.6-87.2% warrants the use of these ligands in quantitative spectrophotometric determination of cobalt (II).(Author)

Heterobimetallic gadolinium(III)-iron(III) complex of DTPA-bis(3-hydroxytyramide)

International Nuclear Information System (INIS)

Parac-Vogt, Tatjana N.; Kimpe, Kristof; Binnemans, Koen

2004-01-01

A derivative of diethylenetriamine-N,N,N',N'',N''-pentaacetic acid (DTPA), carrying two catechol functional groups has been synthesised by the reaction between DTPA-bis(anhydride) and 3-hydroxytyramine (dopamine). The ligand DTPA-bis(3-hydroxytyramide), [DTPA(HTA) 2 ], is able to form stable heterobimetallic complexes with gadolinium(III) and iron(III) ions. The gadolinium(III) occupies the internal coordination cage of DTPA formed by three nitrogens, two carboxylate and two amide oxygens, while the [Fe(NTA)(H 2 O) 2 ] (nitrilotriacetic acid, NTA) binds to catechol units by the substitution of two water ligands. The formation of polymeric species was avoided by using the tripodal NTA ligand. The heterobimetallic complex was characterised by means of visible absorption spectroscopy, electron spray ionisation-mass spectrometry (ESI-MS), and nuclear magnetic resonance (NMR) spectroscopy

Nanostructured Thin Films Obtained from Fischer Aminocarbene Complexes

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Rosa E. Lazo-Jiménez

2016-03-01

Full Text Available The synthesis of four amphiphilic organometallic complexes with the general formula RC = M(CO5NH(CH215CH3, where R is a ferrocenyl 2(a-b or a phenyl 4(a-b group as a donor moiety and a Fischer carbene of chromium (0 or tungsten (0 as an acceptor group, are reported. These four push-pull systems formed Langmuir (L monolayers at the air-water interface, which were characterized by isotherms of surface pressure versus molecular area and compression/expansion cycles (hysteresis curves; Brewster angle microscopic images were also obtained. By using the Langmuir–Blodgett (LB method, molecular monolayers were transferred onto glass substrates forming Z-type multilayers. LB films were characterized through ultraviolet-visible spectroscopy, atomic force microscopy and X-ray diffraction techniques. Results indicated that films obtained from 2b complex [(Ferrocenyl(hexadecylaminemethylidene] pentacarbonyl tungsten (0 are the most stable and homogeneous; due to their properties, these materials may be incorporated into organic electronic devices.

Nanostructured Thin Films Obtained from Fischer Aminocarbene Complexes

Science.gov (United States)

Lazo-Jiménez, Rosa E.; Ortega-Alfaro, M. Carmen; López-Cortés, José G.; Alvarez-Toledano, Cecilio; Chávez-Carvayar, José Á.; Ignés-Mullol, Jordi; González-Torres, Maykel; Carreón-Castro, Pilar

2016-01-01

The synthesis of four amphiphilic organometallic complexes with the general formula RC = M(CO)5NH(CH2)15CH3, where R is a ferrocenyl 2(a-b) or a phenyl 4(a-b) group as a donor moiety and a Fischer carbene of chromium (0) or tungsten (0) as an acceptor group, are reported. These four push-pull systems formed Langmuir (L) monolayers at the air-water interface, which were characterized by isotherms of surface pressure versus molecular area and compression/expansion cycles (hysteresis curves); Brewster angle microscopic images were also obtained. By using the Langmuir–Blodgett (LB) method, molecular monolayers were transferred onto glass substrates forming Z-type multilayers. LB films were characterized through ultraviolet-visible spectroscopy, atomic force microscopy and X-ray diffraction techniques. Results indicated that films obtained from 2b complex [(Ferrocenyl)(hexadecylamine)methylidene] pentacarbonyl tungsten (0) are the most stable and homogeneous; due to their properties, these materials may be incorporated into organic electronic devices. PMID:28773289

Preparation and thermal energy storage properties of paraffin/calcined diatomite composites as form-stable phase change materials

International Nuclear Information System (INIS)

Sun, Zhiming; Zhang, Yuzhong; Zheng, Shuilin; Park, Yuri; Frost, Ray L.

2013-01-01

Highlights: ► Composite phase change material (PCM) was prepared by blending composite paraffin and calcined diatomite. ► The optimum mixed proportion was obtained through differential scanning calorimetry. ► Thermal energy storage properties of the composite PCMs were determined by DSC. ► Thermal cycling test showed that the prepared PCMs are thermally reliable and chemically stable. - Abstract: A composite paraffin-based phase change material (PCM) was prepared by blending composite paraffin and calcined diatomite through the fusion adsorption method. In this study, raw diatomite was purified by thermal treatment in order to improve the adsorption capacity of diatomite, which acted as a carrier material to prepare shape-stabilized PCMs. Two forms of paraffin (paraffin waxes and liquid paraffin) with different melting points were blended together by the fusion method, and the optimum mixed proportion with a suitable phase-transition temperature was obtained through differential scanning calorimetry (DSC) analysis. Then the prepared composite paraffin was adsorbed in calcined diatomite. The prepared paraffin/calcined diatomite composites were characterized by the scanning electron microscope (SEM) and Fourier transformation infrared (FT-IR) analysis techniques. Thermal energy storage properties of the composite PCMs were determined by DSC method. DSC results showed that there was an optimum adsorption ratio between composite paraffin and calcined diatomite and the phase-transition temperature and the latent heat of the composite PCMs were 33.04 °C and 89.54 J/g, respectively. Thermal cycling test of composite PCMs showed that the prepared material is thermally reliable and chemically stable. The obtained paraffin/calcined diatomite composites have proper latent heat and melting temperatures, and show practical significance and good potential application value

Preparation and thermal energy storage properties of paraffin/calcined diatomite composites as form-stable phase change materials

Energy Technology Data Exchange (ETDEWEB)

Sun, Zhiming [School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, 2 George Street, GPO Box 2434, Brisbane, Queensland 4001 (Australia); Zhang, Yuzhong [School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Zheng, Shuilin, E-mail: shuilinzh@yahoo.com.cn [School of Chemical and Environmental Engineering, China University of Mining and Technology, Beijing 100083 (China); Park, Yuri [Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, 2 George Street, GPO Box 2434, Brisbane, Queensland 4001 (Australia); Frost, Ray L., E-mail: r.frost@qut.edu.au [Chemistry Discipline, Faculty of Science and Technology, Queensland University of Technology, 2 George Street, GPO Box 2434, Brisbane, Queensland 4001 (Australia)

2013-04-20

Highlights: ► Composite phase change material (PCM) was prepared by blending composite paraffin and calcined diatomite. ► The optimum mixed proportion was obtained through differential scanning calorimetry. ► Thermal energy storage properties of the composite PCMs were determined by DSC. ► Thermal cycling test showed that the prepared PCMs are thermally reliable and chemically stable. - Abstract: A composite paraffin-based phase change material (PCM) was prepared by blending composite paraffin and calcined diatomite through the fusion adsorption method. In this study, raw diatomite was purified by thermal treatment in order to improve the adsorption capacity of diatomite, which acted as a carrier material to prepare shape-stabilized PCMs. Two forms of paraffin (paraffin waxes and liquid paraffin) with different melting points were blended together by the fusion method, and the optimum mixed proportion with a suitable phase-transition temperature was obtained through differential scanning calorimetry (DSC) analysis. Then the prepared composite paraffin was adsorbed in calcined diatomite. The prepared paraffin/calcined diatomite composites were characterized by the scanning electron microscope (SEM) and Fourier transformation infrared (FT-IR) analysis techniques. Thermal energy storage properties of the composite PCMs were determined by DSC method. DSC results showed that there was an optimum adsorption ratio between composite paraffin and calcined diatomite and the phase-transition temperature and the latent heat of the composite PCMs were 33.04 °C and 89.54 J/g, respectively. Thermal cycling test of composite PCMs showed that the prepared material is thermally reliable and chemically stable. The obtained paraffin/calcined diatomite composites have proper latent heat and melting temperatures, and show practical significance and good potential application value.

Stable isotope views on ecosystem function: challenging or challenged?

Science.gov (United States)

Resco, Víctor; Querejeta, José I.; Ogle, Kiona; Voltas, Jordi; Sebastià, Maria-Teresa; Serrano-Ortiz, Penélope; Linares, Juan C.; Moreno-Gutiérrez, Cristina; Herrero, Asier; Carreira, José A.; Torres-Cañabate, Patricia; Valladares, Fernando

2010-01-01

Stable isotopes and their potential for detecting various and complex ecosystem processes are attracting an increasing number of scientists. Progress is challenging, particularly under global change scenarios, but some established views have been challenged. The IX meeting of the Spanish Association of Terrestrial Ecology (AAET, Úbeda, 18–22 October 2009) hosted a symposium on the ecology of stable isotopes where the linear mixing model approach of partitioning sinks and sources of carbon and water fluxes within an ecosystem was challenged, and new applications of stable isotopes for the study of plant interactions were evaluated. Discussion was also centred on the need for networks that monitor ecological processes using stable isotopes and key ideas for fostering future research with isotopes. PMID:20015858

Financial Support of the Forestry Complex Development Priorities: Diversification of Forms and Means

OpenAIRE

Golyan Vasyl A.; Holub Oleh A.

2016-01-01

It is found that at the present stage the funding of the forestry complex development priorities occurs in the following forms: 1) the budget financing of reforestation; 2) financial support of forestry and forest protection projects with the use of funds raised by public and private entities of forest entrepreneurship on the basis of self-financing activities; 3) the receiving of financial resources by forestry entrepreneurship entities as a result of compensation of losses...

A New Modular Approach to Nanoassembly: Stable and Addressable DNA Nanoconstructs via Orthogonal Click Chemistries

KAUST Repository

Gerrard, Simon R.

2012-10-23

Thermodynamic instability is a problem when assembling and purifying complex DNA nanostructures formed by hybridization alone. To address this issue, we have used photochemical fixation and orthogonal copper-free, ring-strain-promoted, click chemistry for the synthesis of dimeric, trimeric, and oligomeric modular DNA scaffolds from cyclic, double-stranded, 80-mer DNA nanoconstructs. This particular combination of orthogonal click reactions was more effective for nanoassembly than others explored. The complex nanostructures are stable to heat and denaturation agents and can therefore be purified and characterized. They are addressable in a sequence-specific manner by triplex formation, and they can be reversibly and selectively deconstructed. Nanostructures utilizing this orthogonal, chemical fixation methodology can be used as building blocks for nanomachines and functional DNA nanoarchitectures. © 2012 American Chemical Society.

Purification and spectroscopic characterization of photosystem II reaction center complexes isolated with or without Triton X-100.

NARCIS (Netherlands)

Eijckelhoff, C.; van Roon, H.; Groot, M.L.; van Grondelle, R.; Dekker, J.P.

1996-01-01

The pigment composition of the isolated photosystem II reaction center complex in its most stable and pure form currently is a matter of considerable debate. In this contribution, we present a new method based on a combination of gel filtration chromatography and diode array detection to analyze the

Manufacture of a four-sheet complex component from different titanium alloys by superplastic forming

Science.gov (United States)

Allazadeh, M. R.; Zuelli, N.

2017-10-01

A superplastic forming (SPF) technology process was deployed to form a complex component with eight-pocket from a four-sheet sandwich panel sheetstock. Six sheetstock packs were composed of two core sheets made of Ti-6Al-4V or Ti-5Al-4Cr-4Mo-2Sn-2Zr titanium alloy and two skin sheets made of Ti-6Al-4V or Ti-6Al-2Sn-4Zr-2Mo titanium alloy in three different combinations. The sheets were welded with two subsequent welding patterns over the core and skin sheets to meet the required component's details. The applied welding methods were intermittent and continuous resistance seam welding for bonding the core sheets to each other and the skin sheets over the core panel, respectively. The final component configuration was predicted based on the die drawings and finite element method (FEM) simulations for the sandwich panels. An SPF system set-up with two inlet gas pipe feeding facilitated the trials to deliver two pressure-time load cycles acting simultaneously which were extracted from FEM analysis for specific forming temperature and strain rate. The SPF pressure-time cycles were optimized via GOM scanning and visually inspecting some sections of the packs in order to assess the levels of core panel formation during the inflation process of the sheetstock. Two sets of GOM scan results were compared via GOM software to inspect the surface and internal features of the inflated multisheet packs. The results highlighted the capability of the tested SPF process to form complex components from a flat multisheet pack made of different titanium alloys.

FILAMENTARY STRUCTURE OF STAR-FORMING COMPLEXES

International Nuclear Information System (INIS)

Myers, Philip C.

2009-01-01

The nearest young stellar groups are associated with 'hubs' of column density exceeding 10 22 cm -2 , according to recent observations. These hubs radiate multiple 'filaments' of parsec length, having lower column density and fewer stars. Systems with many filaments tend to have parallel filaments with similar spacing. Such 'hub-filament structure' is associated with all of the nine young stellar groups within 300 pc, forming low-mass stars. Similar properties are seen in infrared dark clouds forming more massive stars. In a new model, an initial clump in a uniform medium is compressed into a self-gravitating, modulated layer. The outer layer resembles the modulated equilibrium of Schmid-Burgk with nearly parallel filaments. The filaments converge onto the compressed clump, which collapses to form stars with high efficiency. The initial medium and condensations have densities similar to those in nearby star-forming clouds and clumps. The predicted structures resemble observed hub-filament systems in their size, shape, and column density, and in the appearance of their filaments. These results suggest that HFS associated with young stellar groups may arise from compression of clumpy gas in molecular clouds.

Stable preparations of tyrosine hydroxylase provide the solution structure of the full-length enzyme

Science.gov (United States)

Bezem, Maria T.; Baumann, Anne; Skjærven, Lars; Meyer, Romain; Kursula, Petri; Martinez, Aurora; Flydal, Marte I.

2016-01-01

Tyrosine hydroxylase (TH) catalyzes the rate-limiting step in the biosynthesis of catecholamine neurotransmitters. TH is a highly complex enzyme at mechanistic, structural, and regulatory levels, and the preparation of kinetically and conformationally stable enzyme for structural characterization has been challenging. Here, we report on improved protocols for purification of recombinant human TH isoform 1 (TH1), which provide large amounts of pure, stable, active TH1 with an intact N-terminus. TH1 purified through fusion with a His-tagged maltose-binding protein on amylose resin was representative of the iron-bound functional enzyme, showing high activity and stabilization by the natural feedback inhibitor dopamine. TH1 purified through fusion with a His-tagged ZZ domain on TALON is remarkably stable, as it was partially inhibited by resin-derived cobalt. This more stable enzyme preparation provided high-quality small-angle X-ray scattering (SAXS) data and reliable structural models of full-length tetrameric TH1. The SAXS-derived model reveals an elongated conformation (Dmax = 20 nm) for TH1, different arrangement of the catalytic domains compared with the crystal structure of truncated forms, and an N-terminal region with an unstructured tail that hosts the phosphorylation sites and a separated Ala-rich helical motif that may have a role in regulation of TH by interacting with binding partners. PMID:27462005

Preparation, description and properties of {sup 3}H- DNA - {sup 131}I-ribonuclease complexes; Preparation, caracterisation et proprietes des complexes ADN{sup 3}H - RNase {sup 131}I

Energy Technology Data Exchange (ETDEWEB)

Tshitenge, G. [Centre nucléaire TRICO, Kinshasa (Congo, The Democratic Republic of the); Ledoux, L. [Centre d’étude de l' énergie nucléaire Mol (Belgium)

1970-01-15

Bacterial DNA, both radioactive and non-radioactive, and pancreatic ribonuclease labelled with iodine-131 are mixed together at a high ion strength and neutral pH. They are then dialysed against 0.009M sodium chloride. During dialysis a precipitate is formed, which is then separated with a centrifuge and redissolved at a neutral pH in a 0.1M phosphate buffer solution, or in 0.15M sodium chloride and 0.015M sodium citrate solution adjusted to pH 7. This solution is then analysed: (1) by DEAE-cellulose paper chromatography using a centrifuge; (2) by sedimentation of caesium chloride along a gradient; (3) by electrophoresis in agar gel. The results obtained show that a stable complex is formed between the DNA and ribonuclease. The properties of this complex are such that it can be compared with natural nucleoproteins. (author) [French] Des ADN bactériens radioactifs ou non et de la ribonucléase pancréatique marquée a l'iode-131 sont mélangés, à force ionique élevée et à pH neutre. Ils sont ensuite dialyses contre du NaCl 0.009M. Au cours de cette dialyse, un précipité se forme. Ce précipité est séparé par centrifugation et redissous à pH neutre dans du tampon phosphate 0,1M, ou dans une solution 0.015M en citrate de Na et 0,15M en NaCl ajustée à pH 7. Cette solution a été analysée: 1) par Chromatographie centrifugée sur pulpe de papier de DEAE- cellulose; 2) par sédimentation en gradient de CsCl; 3) par électrophorèse en gel d'agar. Les résultats obtenus montrent qu'un complexe stable sfest formé entre l'ADN et la RNase. Les propriétés de ce complexe permettent de le comparer aux nucléoprotéines naturelles. (author)

The Enhanced Intramolecular Energy Transfer and Strengthened ff Luminescence of a Stable Helical Eu Complex in Ionic Liquids

Directory of Open Access Journals (Sweden)

Yuki Hasegawa

2018-01-01

Full Text Available The luminescence of a Eu complex (EuL is enhanced by stabilization of the coordination structure in highly viscous ionic liquids. The EuL was found to maintain a stable single helical structure both in organic solvents and in the ionic liquids [BMIM][PF6] and [EMIM][PF6]. A colorless solution of EuL dissolved in [BMIM][PF6] exhibits bright red luminescence with a quantum yield of 32.3%, a value that is much higher than that in acetonitrile (12%. Estimated rate constants for the energy relaxation pathway indicate that the energy transfer efficiency is enhanced in [BMIM][PF6] as a result of the suppression of molecular fluctuations in the ligands. Additionally, a highly luminescent helical structure is preserved in [EMIM][PF6] up to 120 °C.

Trypanin, a component of the flagellar Dynein regulatory complex, is essential in bloodstream form African trypanosomes.

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Katherine S Ralston

2006-09-01

Full Text Available The Trypanosoma brucei flagellum is a multifunctional organelle with critical roles in motility, cellular morphogenesis, and cell division. Although motility is thought to be important throughout the trypanosome lifecycle, most studies of flagellum structure and function have been restricted to the procyclic lifecycle stage, and our knowledge of the bloodstream form flagellum is limited. We have previously shown that trypanin functions as part of a flagellar dynein regulatory system that transmits regulatory signals from the central pair apparatus and radial spokes to axonemal dyneins. Here we investigate the requirement for this dynein regulatory system in bloodstream form trypanosomes. We demonstrate that trypanin is localized to the flagellum of bloodstream form trypanosomes, in a pattern identical to that seen in procyclic cells. Surprisingly, trypanin RNA interference is lethal in the bloodstream form. These knockdown mutants fail to initiate cytokinesis, but undergo multiple rounds of organelle replication, accumulating multiple flagella, nuclei, kinetoplasts, mitochondria, and flagellum attachment zone structures. These findings suggest that normal flagellar beat is essential in bloodstream form trypanosomes and underscore the emerging concept that there is a dichotomy between trypanosome lifecycle stages with respect to factors that contribute to cell division and cell morphogenesis. This is the first time that a defined dynein regulatory complex has been shown to be essential in any organism and implicates the dynein regulatory complex and other enzymatic regulators of flagellar motility as candidate drug targets for the treatment of African sleeping sickness.

Structural characterization of the Actinides (III) and (IV) - DOTA complexes

International Nuclear Information System (INIS)

Audras, Matthieu

2014-01-01

cation is located inside the cavity formed by the macrocycle DOTA. However, the kinetics of actinide(IV) complexation is slower than for the actinides(III) complexation. Moreover, the study of thorium(IV)-DOTA complexes shows differences since 1:1 and 1:2 complexes in solution are detected, and where only the carboxylate functions are involved in the coordination sphere of the cation. Finally, an initial estimate of the stability constant of the plutonium(IV)-DOTA complexes by electrochemical measurements indicates that complexes of actinide(IV) are approximately 10 orders of magnitude more stable than complexes of actinides(III), as previously observed with other polyamino-carboxylate anions. (author) [fr

Quantum mechanical calculation of aqueuous uranium complexes: carbonate, phosphate, organic and biomolecular species

Directory of Open Access Journals (Sweden)

Jha Prashant

2009-08-01

Full Text Available Abstract Background Quantum mechanical calculations were performed on a variety of uranium species representing U(VI, U(V, U(IV, U-carbonates, U-phosphates, U-oxalates, U-catecholates, U-phosphodiesters, U-phosphorylated N-acetyl-glucosamine (NAG, and U-2-Keto-3-doxyoctanoate (KDO with explicit solvation by H2O molecules. These models represent major U species in natural waters and complexes on bacterial surfaces. The model results are compared to observed EXAFS, IR, Raman and NMR spectra. Results Agreement between experiment and theory is acceptable in most cases, and the reasons for discrepancies are discussed. Calculated Gibbs free energies are used to constrain which configurations are most likely to be stable under circumneutral pH conditions. Reduction of U(VI to U(IV is examined for the U-carbonate and U-catechol complexes. Conclusion Results on the potential energy differences between U(V- and U(IV-carbonate complexes suggest that the cause of slower disproportionation in this system is electrostatic repulsion between UO2 [CO3]35- ions that must approach one another to form U(VI and U(IV rather than a change in thermodynamic stability. Calculations on U-catechol species are consistent with the observation that UO22+ can oxidize catechol and form quinone-like species. In addition, outer-sphere complexation is predicted to be the most stable for U-catechol interactions based on calculated energies and comparison to 13C NMR spectra. Outer-sphere complexes (i.e., ion pairs bridged by water molecules are predicted to be comparable in Gibbs free energy to inner-sphere complexes for a model carboxylic acid. Complexation of uranyl to phosphorus-containing groups in extracellular polymeric substances is predicted to favor phosphonate groups, such as that found in phosphorylated NAG, rather than phosphodiesters, such as those in nucleic acids.

Financial Support of the Forestry Complex Development Priorities: Diversification of Forms and Means

Directory of Open Access Journals (Sweden)

Golyan Vasyl A.

2016-08-01

Full Text Available It is found that at the present stage the funding of the forestry complex development priorities occurs in the following forms: 1 the budget financing of reforestation; 2 financial support of forestry and forest protection projects with the use of funds raised by public and private entities of forest entrepreneurship on the basis of self-financing activities; 3 the receiving of financial resources by forestry entrepreneurship entities as a result of compensation of losses in forestry production; 4 the financing of environmental protection measures relating to reproduction of the forest resource potential due to the environmental tax and the rent. There identified main negative factors affecting financial activities of permanent forest users — state forestry enterprises, which include: the lack of a mechanism of rational use of the forest resources export potential caused by the insignificant proportion of products with a high share of added value; a latent character of the mechanism for stimulating deep timber processing; underdeveloped mechanisms of regulating the flow of forest rents from the forestry to the timber processing segment of the forest-based sector. There improved theoretical and methodological approaches to diversification of forms and means of funding the development priorities of the forest-based sector, which involve raising the level of concentration of the investmentpotential of forestry and timber processing subdivisions of the territorial and forestry complex through forming integrated business associations of the holding and cluster type; separating the timber processing from forestry, which will ensure the equal level of access for timber processing businesses of different forms of ownership to unprocessed timber and will contribute to increasing the level of capitalization of forest and forestry assets; extension of the specification of forestry and forest protection activities, which will improve the efficiency of

Structure of stable degeneration of K3 surfaces into pairs of rational elliptic surfaces

OpenAIRE

Kimura, Yusuke

2018-01-01

F-theory/heterotic duality is formulated in the stable degeneration limit of a K3 fibration on the F-theory side. In this note, we analyze the structure of the stable degeneration limit. We discuss whether stable degeneration exists for pairs of rational elliptic surfaces. We demonstrate that, when two rational elliptic surfaces have an identical complex structure, stable degeneration always exists. We provide an equation that systematically describes the stable degeneration of a K3 surface i...

(2+1)-dimensional stable spatial Raman solitons

International Nuclear Information System (INIS)

Shverdin, M.Y.; Yavuz, D.D.; Walker, D.R.

2004-01-01

We analyze the formation, propagation, and interaction of stable two-frequency (2+1)-dimensional solitons, formed in a Raman media driven near maximum molecular coherence. The propagating light is trapped in the two transverse dimensions

Pesticides Curbing Soil Fertility: Effect of Complexation of Free Metal Ions

Science.gov (United States)

Kaur, Sukhmanpreet; Kumar, Vijay; Chawla, Mohit; Cavallo, Luigi; Poater, Albert; Upadhyay, Niraj

2017-07-01

Researchers have suggested that the reason behind infertility is pernicious effect of broad spectrum pesticides on non target, beneficial microorganism of soil. Here, studying the chelating effect of selective organophosphate and carbamate pesticides with essential metal ions, at all possible combinations of three different pH (4±0.05, 7±0.05 and 9±0.05) and three different temperatures (15±0.5°C, 30±0.5°C and 45±0.5°C), shows very fast rate of reaction which further increases with increase of pH and temperature. Carbonyl oxygen of carbamate and phosphate oxygen of organophosphate were found to be common ligating sites among all the complexes. Formed metal complexes were found to be highly stable and water insoluble on interaction with essential metal ions in solvent medium as well as over silica. Density functional theory (DFT) calculations not only reinforced the experimental observations, but, after a wide computational conformational analysis, unraveled the nature of the high stable undesired species that consist of pesticides complexed by metal ions from the soil. All in all, apart from the direct toxicity of pesticides, the indirect effect by means of complexation of free metal ions impoverishes the soil.

Pesticides Curbing Soil Fertility: Effect of Complexation of Free Metal Ions

KAUST Repository

Kaur, Sukhmanpreet

2017-07-04

Researchers have suggested that the reason behind infertility is pernicious effect of broad spectrum pesticides on non target, beneficial microorganism of soil. Here, studying the chelating effect of selective organophosphate and carbamate pesticides with essential metal ions, at all possible combinations of three different pH (4 ± 0.05, 7 ± 0.05 and 9 ± 0.05) and three different temperatures (15 ± 0.5°C, 30 ± 0.5°C and 45 ± 0.5°C), shows very fast rate of reaction which further increases with increase of pH and temperature. Carbonyl oxygen of carbamate and phosphate oxygen of organophosphate were found to be common ligating sites among all the complexes. Formed metal complexes were found to be highly stable and water insoluble on interaction with essential metal ions in solvent medium as well as over silica. Density functional theory (DFT) calculations not only reinforced the experimental observations, but, after a wide computational conformational analysis, unraveled the nature of the high stable undesired species that consist of pesticides complexed by metal ions from the soil. All in all, apart from the direct toxicity of pesticides, the indirect effect by means of complexation of free metal ions impoverishes the soil.

Pesticides Curbing Soil Fertility: Effect of Complexation of Free Metal Ions

KAUST Repository

Kaur, Sukhmanpreet; Kumar, Vijay; Chawla, Mohit; Cavallo, Luigi; Poater, Albert; Upadhyay, Niraj

2017-01-01

Researchers have suggested that the reason behind infertility is pernicious effect of broad spectrum pesticides on non target, beneficial microorganism of soil. Here, studying the chelating effect of selective organophosphate and carbamate pesticides with essential metal ions, at all possible combinations of three different pH (4 ± 0.05, 7 ± 0.05 and 9 ± 0.05) and three different temperatures (15 ± 0.5°C, 30 ± 0.5°C and 45 ± 0.5°C), shows very fast rate of reaction which further increases with increase of pH and temperature. Carbonyl oxygen of carbamate and phosphate oxygen of organophosphate were found to be common ligating sites among all the complexes. Formed metal complexes were found to be highly stable and water insoluble on interaction with essential metal ions in solvent medium as well as over silica. Density functional theory (DFT) calculations not only reinforced the experimental observations, but, after a wide computational conformational analysis, unraveled the nature of the high stable undesired species that consist of pesticides complexed by metal ions from the soil. All in all, apart from the direct toxicity of pesticides, the indirect effect by means of complexation of free metal ions impoverishes the soil.

Spectrophotometric study of the complexes of cerium and uranides with diethylenetetraaminepentaacetic acid (DTPA); Contribution a l'etude de la complexation du cerium et des uranides par l'acide diethylenetetraminepentaacetique (DTPA)

Energy Technology Data Exchange (ETDEWEB)

Hafez, M B [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1968-03-01

A spectrophotometric determination was made of the complexes of cerium and uranides in their different degrees of oxidation with diethylenetriaminepentaacetic acid (DTPA). Two physico-chemical states, the ionic and hydrolysis ones, were considered. In the former case, we studied the influence of the pH on the formation of the complex, and whenever the complexes were stable, we determined the molecular ratio and calculated their stability constants. In the latter case, we studied the conditions of solubilization of the precipitate by formation of complexes soluble in water as a function of pH, age of the precipitate and time of precipitate-chelate contact. (authors) [French] Etude spectrophotometrique de la complexation du cerium et des uranides (uranium, neptunium, plutonium et americium) dans leurs differents etats d'oxydation par l'acide diethylenetriaminepentaacetique (DTPA). Deux etats physicochimiques ont retenu notre attention, l'etat ionique et l'etat precipite d'hydrolyse. Dans le premier cas, nous avons etudie l'influence du pH sur la formation du complexe, et dans tous les cas ou le complexe est stable, nous avons determine le rapport moleculaire (5) [element]/[chelatant] du complexe forme et nous avons calcule leurs constantes de stabilite. Dans le deuxieme cas, l'etat de precipite d'hydrolyse, nous avons etudie les conditions de solubilisation du precipite, par formation du complexe, en fonction du pH, de l'age du precipite et du temps de contact precipite - chelatant. (auteurs)

Interaction of Cr (III), Ni (II), Pb (II) with DTPA complexes of essential metal ions

International Nuclear Information System (INIS)

Gulzar, S.; Zahida; Maqsood, T.; Naqvi, R.R.

2002-01-01

With the increase of anthropogenic activities in the environment, heavy metal toxicity (Chromium, Nickel and Lead) is more common now. DTPA (diethylene triamine pentaacetic acid) a polyamino carboxylic acid is widely used to form hydrophilic and stable complexes with most of the metal ions. In this spectrophotometric study, concentration of Cr(III), Ni(II) and Pb(II) (toxic metal ions) exchanged with Fe(III), Zn(II) and Ca(II) from their DTPA complexes were estimated at pH 4,7 and 9. Concentration of added metal was varied from 1-4 times to that of complexed metal. (author)

Formation, transformation and dissolution of phases formed on surfaces

International Nuclear Information System (INIS)

Shoesmith, D.W.

1983-03-01

The basic mechanisms of film growth, transformation, and dissolution of phases formed on surfaces are discussed. Film growth can occur via solid-state processes or via substrate (usally metal or alloy) dissolution, followed by local supersaturation and precipitation of an insoluble phase. The phase(s) formed may be metastable and transform to a more stable phase, via either solid-state or dissolution-reprecipitation processes. Film dissolution reactions can also occur via a variety of mechanisms, including: (i) direct chemical dissolution when no oxidation state change occurs; (ii) redox dissolution when the film dissolves via a redox reaction involving a reducing or oxidizing agent in solution; and (iii) autoreduction, where film dissolution is coupled to metal dissolution. Such film-growth and dissolution processes, which often produce complex multilayer films, are common in the nuclear industry. A number of examples are discussed

Crystallization and preliminary crystallographic studies of the YafN–YafO complex from Escherichia coli

International Nuclear Information System (INIS)

Zhang, Fan; Xing, Li; Teng, Maikun; Li, Xu

2012-01-01

The ribosome-dependent mRNA interferase YafO from Escherichia coli belongs to a type II toxin–antitoxin (TA) system and its cognate antitoxin YafN neutralizes cell toxicity by forming a stable YafN–YafO complex. Here, the YafN–YafO complex has been expressed and crystallized. The ribosome-dependent mRNA interferase YafO from Escherichia coli belongs to a type II toxin–antitoxin (TA) system and its cognate antitoxin YafN neutralizes cell toxicity by forming a stable YafN–YafO complex. The YafN–YafO TA system is upregulated by the SOS response (a global response to DNA damage in which the cell cycle is arrested and mutagenesis is induced) and may then inhibit protein synthesis by endoribonuclease activity of YafO with the 50S ribosome subunit. Structural information on the YafN–YafO complex and related complexes would be helpful in order to understand the structural basis of the mechanism of mRNA recognition and cleavage, and the assembly of these complexes. Here, the YafN–YafO complex was expressed and crystallized. Crystals grown by the hanging-drop vapour-diffusion method diffracted to 3.50 Å resolution and belonged to the hexagonal space group P622, with unit-cell parameters a = 86.14, b = 86.14, c = 173.11 Å, α = β = 90, γ = 120°. Both Matthews coefficient analysis and the self-rotation function suggested the presence of one molecule per asymmetric unit in the crystal, with a solvent content of 65.69% (V M = 3.58 Å 3 Da −1 )

Extractive spectrophotometric determination of five selected drugs by ion-pair complex formation with bromothymol blue in pure form and pharmaceutical preparations

Directory of Open Access Journals (Sweden)

Sneha G. Nair

2015-12-01

Full Text Available Simple, precise, selective, and expeditious spectrophotometric methods have been developed for the determination of itopride (ITO, midodrine (MID, diclofenac (DIC, mesalamine (MES, and sumatriptan (SUM in their pure form as well as in pharmaceutical preparations. The method was based on ion-pair complex formation between the drugs and anionic dye, bromothymol blue in an acidic medium (pH 2.0–4.0. The yellow colored complexes formed were quantitatively extracted into chloroform and measured at 411, 410, 413, 412, and 414 nm wavelength for ITO, MID, DIC, MES, and SUM, respectively. Beer’s law was obeyed in the concentration range of 3.0–30 µg/mL for ITO, 1.0–20 µg/mL for MID, 1.5–40 µg/mL for DIC, 1.2–12 µg/mL for MES, and 0.5–15 µg/mL for SUM. The stoichiometry of the complexes formed between the drugs and the dye was 1:1 as determined by Job’s method of continuous variation. The association constant (KIP of the ion-pair complexes formed was evaluated using Benesi–Hildebrand equation. Limit of detection, limit of quantification, and Sandell’s sensitivity of the methods were also estimated. The proposed methods were successfully employed for the determination of these drugs in their pharmaceutical dosage forms.

Mechanochemical Preparation of Stable Sub-100 nm γ-Cyclodextrin:Buckminsterfullerene (C60) Nanoparticles by Electrostatic or Steric Stabilization.

Science.gov (United States)

Van Guyse, Joachim F R; de la Rosa, Victor R; Hoogenboom, Richard

2018-02-21

Buckminster fullerene (C 60 )'s main hurdle to enter the field of biomedicine is its low bioavailability, which results from its extremely low water solubility. A well-known approach to increase the water solubility of C 60 is by complexation with γ-cyclodextrins. However, the formed complexes are not stable in time as they rapidly aggregate and eventually precipitate due to attractive intermolecular forces, a common problem in inclusion complexes of cyclodextrins. In this study we attempt to overcome the attractive intermolecular forces between the complexes by designing custom γ-cyclodextrin (γCD)-based supramolecular hosts for C 60 that inhibit the aggregation found in native γCD-C 60 complexes. The approach entails the introduction of either repulsive electrostatic forces or increased steric hindrance to prevent aggregation, thus enhancing the biomedical application potential of C 60 . These modifications have led to new sub-100 nm nanostructures that show long-term stability in solution. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cadmium complexation by solid waste leachates

DEFF Research Database (Denmark)

Xu Ze Lun; Christensen, Thomas H.

1989-01-01

A previously reported method for determination of Cd species in solid waste leachates has been applied to ten leachate samples representing five different types of solid waste: refuse compost, flyash from coal combustion, sewage sludge, refuse incineration residues and landfilled municipal waste......, slowly labile complexes and stable complexes. Leachates originating from the same type of solid waste showed different fractions of Cd, in particular with respect to free divalent Cd and stable Cd complexes. Only coal flyash showed almost identical fractions of Cd in the two leachates. The latter is due...

Hermitian-Einstein metrics on parabolic stable bundles

International Nuclear Information System (INIS)

Li Jiayu; Narasimhan, M.S.

1995-12-01

Let M-bar be a compact complex manifold of complex dimension two with a smooth Kaehler metric and D a smooth divisor on M-bar. If E is a rank 2 holomorphic vector bundle on M-bar with a stable parabolic structure along D, we prove the existence of a metric on E' = E module MbarD (compatible with the parabolic structure) which is Hermitian-Einstein with respect to the restriction of Kaehler metric of M-barD. A converse is also proved. (author). 24 refs

Preparation and chemical studies on Tc(III) complexes containing polyaminocarboxylic acids

International Nuclear Information System (INIS)

Gonzalez, R.; Kremer, C.; Chiozzone, R.; Torres, J.; Rivero, M.; Kremer, E.; Leon, A.

1998-01-01

Tc(III)-edta (edta = ethylenediaminetetraacetate), Tc(III)-dtpa (dtpa = diethylenetriaminepentaacetate) and Tc(III)-mebrofenin (mebrofenin = 3-bromo-2,4,6-trimethylacetanilideiminodiacetate) complexes were prepared by ligand substitution reactions on hexakis(thiourea)technetium(III) cation with the polycarboxylates. By a combination of different techniques (UV-Vis, IR and 1 H-NMR spectroscopy, Tc elemental analyses and cerimetric titrations) it was concluded that 1:1 complexes are formed with edta and dtpa while mebrofening adopts a 2:1 (ligand to metal) stoichiometry. Complementary, molecular mechanics calculations were performed to analyze the spatial arrangement of the molecules. The stability of the Tc(III) complexes was studied in aqueous solution by paper chromatography, paper electrophoresis and cyclic voltammetry. The chelates are rather stable, in particular when compared with the precursor. (orig.)

Study on complexation behaviour of uranium and thorium with amino acids at different temperatures in aqueous media

International Nuclear Information System (INIS)

Joshi, J.D.; Patel, M.R.; Patel, A.D.

1992-01-01

The complexation behaviour of uranium and thorium with important amino acids have been studied using Irving-Rossotti titration technique at 25deg, 35deg and 45degC in inert atmosphere of nitrogen and 0.1M ionic strength using NaClO 4 . The thermodynamic parameters ΔG, ΔH and ΔS have been calculated. Results indicate that thorium (IV) is forming more stable complexes than UO 2 2+ . (author). 3 refs., 2 tab

Gelatin Zymography Using Leupeptin for the Detection of Various Cathepsin L Forms.

Science.gov (United States)

Hashimoto, Yoko

2017-01-01

Zymography is a highly sensitive method to assess the activities as well as molecular weights of enzymes in crude biological fluids and tissue extracts. Cathepsin L is a lysosomal cysteine proteinase that is optimally active at slightly acidic pH and is highly unstable in alkaline solutions such as electrode buffer (pH 8.3). Large amounts of cathepsin L are secreted by various cancer cells, where it promotes invasion and metastasis. Leupeptin is a tight-binding inhibitor of cysteine proteinases, and its complex with cathepsin L is stable in alkaline solutions. Moreover, leupeptin can be easily removed from the complex because it is a reversibly binding inhibitor. In addition, leupeptin is too small to influence the electrode migration distance of the complex with cathepsin L on a sodium dodecyl sulfate-polyacrylamide gel. Here, a novel gelatin zymography technique that employs leupeptin to detect pro-, intermediate, and mature cathepsin L forms on the basis of their gelatinolytic activities is described. Further, the differences in the glycosylation, phosphorylation, and processing statuses of lysosomal and secreted cathepsin L forms isolated from cultured HT 1080 cells are demonstrated using this method.

Stable isotope labeling strategy based on coding theory

Energy Technology Data Exchange (ETDEWEB)

Kasai, Takuma; Koshiba, Seizo; Yokoyama, Jun; Kigawa, Takanori, E-mail: kigawa@riken.jp [RIKEN Quantitative Biology Center (QBiC), Laboratory for Biomolecular Structure and Dynamics (Japan)

2015-10-15

We describe a strategy for stable isotope-aided protein nuclear magnetic resonance (NMR) analysis, called stable isotope encoding. The basic idea of this strategy is that amino-acid selective labeling can be considered as “encoding and decoding” processes, in which the information of amino acid type is encoded by the stable isotope labeling ratio of the corresponding residue and it is decoded by analyzing NMR spectra. According to the idea, the strategy can diminish the required number of labelled samples by increasing information content per sample, enabling discrimination of 19 kinds of non-proline amino acids with only three labeled samples. The idea also enables this strategy to combine with information technologies, such as error detection by check digit, to improve the robustness of analyses with low quality data. Stable isotope encoding will facilitate NMR analyses of proteins under non-ideal conditions, such as those in large complex systems, with low-solubility, and in living cells.

Stable isotope labeling strategy based on coding theory

International Nuclear Information System (INIS)

Kasai, Takuma; Koshiba, Seizo; Yokoyama, Jun; Kigawa, Takanori

2015-01-01

We describe a strategy for stable isotope-aided protein nuclear magnetic resonance (NMR) analysis, called stable isotope encoding. The basic idea of this strategy is that amino-acid selective labeling can be considered as “encoding and decoding” processes, in which the information of amino acid type is encoded by the stable isotope labeling ratio of the corresponding residue and it is decoded by analyzing NMR spectra. According to the idea, the strategy can diminish the required number of labelled samples by increasing information content per sample, enabling discrimination of 19 kinds of non-proline amino acids with only three labeled samples. The idea also enables this strategy to combine with information technologies, such as error detection by check digit, to improve the robustness of analyses with low quality data. Stable isotope encoding will facilitate NMR analyses of proteins under non-ideal conditions, such as those in large complex systems, with low-solubility, and in living cells

Decomposition of uranyl peroxo-carbonato complex ion in the presence of metal oxides in carbonate media

International Nuclear Information System (INIS)

Dong-Yong Chung; Min-Sung Park; Keun-Young Lee; Eil-Hee Lee; Kwang-Wook Kim; Jei-Kwon Moon

2015-01-01

Uranium oxide was dissolved in the form of the uranyl peroxo-carbonato complex ion, UO 2 (O 2 )(CO 3 ) 2 4- in carbonate solutions with hydrogen peroxide. When UO 2 (O 2 )(CO 3 ) 2 4- ions lose their peroxide component, they become a stable species of uranyl tricarbonato complex ion, UO 2 (O 2 )(CO 3 ) 2 4- . The uranyl peroxo-carbonato complex self-decomposed more rapidly into the uranyl tricarbonato complex ion in the presence of a metal oxide in the carbonate solution. In this study, decomposition of the uranyl peroxo-carbonato complex in a carbonate solution was investigated in the presence of several metal oxides using absorption spectroscopy. (author)

Synthesis and Self-Assembly of Chiral Cylindrical Molecular Complexes: Functional Heterogeneous Liquid-Solid Materials Formed by Helicene Oligomers

Directory of Open Access Journals (Sweden)

Nozomi Saito

2018-01-01

Full Text Available Chiral cylindrical molecular complexes of homo- and hetero-double-helices derived from helicene oligomers self-assemble in solution, providing functional heterogeneous liquid-solid materials. Gels and liotropic liquid crystals are formed by fibril self-assembly in solution; molecular monolayers and fibril films are formed by self-assembly on solid surfaces; gels containing gold nanoparticles emit light; silica nanoparticles aggregate and adsorb double-helices. Notable dynamics appears during self-assembly, including multistep self-assembly, solid surface catalyzed double-helix formation, sigmoidal and stairwise kinetics, molecular recognition of nanoparticles, discontinuous self-assembly, materials clocking, chiral symmetry breaking and homogeneous-heterogeneous transitions. These phenomena are derived from strong intercomplex interactions of chiral cylindrical molecular complexes.

Stable convergence and stable limit theorems

CERN Document Server

Häusler, Erich

2015-01-01

The authors present a concise but complete exposition of the mathematical theory of stable convergence and give various applications in different areas of probability theory and mathematical statistics to illustrate the usefulness of this concept. Stable convergence holds in many limit theorems of probability theory and statistics – such as the classical central limit theorem – which are usually formulated in terms of convergence in distribution. Originated by Alfred Rényi, the notion of stable convergence is stronger than the classical weak convergence of probability measures. A variety of methods is described which can be used to establish this stronger stable convergence in many limit theorems which were originally formulated only in terms of weak convergence. Naturally, these stronger limit theorems have new and stronger consequences which should not be missed by neglecting the notion of stable convergence. The presentation will be accessible to researchers and advanced students at the master's level...

Preparation and thermal properties of form-stable palmitic acid/active aluminum oxide composites as phase change materials for latent heat storage

International Nuclear Information System (INIS)

Fang, Guiyin; Li, Hui; Cao, Lei; Shan, Feng

2012-01-01

Form-stable palmitic acid (PA)/active aluminum oxide composites as phase change materials were prepared by adsorbing liquid palmitic acid into active aluminum oxide. In the composites, the palmitic acid was used as latent heat storage materials, and the active aluminum oxide was used as supporting material. Fourier transformation infrared spectroscope (FT-IR), X-ray diffractometer (XRD) and scanning electronic microscope (SEM) were used to determine the chemical structure, crystalloid phase and microstructure of the composites, respectively. The thermal properties and thermal stability were investigated by a differential scanning calorimeter (DSC) and a thermogravimetry analyzer (TGA). The FT-IR analyses results indicated that there is no chemical interaction between the palmitic acid and active aluminum oxide. The SEM results showed that the palmitic acid was well adsorbed into porous network of the active aluminum oxide. The DSC results indicated that the composites melt at 60.25 °C with a latent heat of 84.48 kJ kg −1 and solidify at 56.86 °C with a latent heat of 78.79 kJ kg −1 when the mass ratio of the PA to active aluminum oxide is 0.9:1. Compared with that of the PA, the melting and solidifying time of the composites CPCM5 was reduced by 20.6% and 21.4% because of the increased heat transfer rate through EG addition. The TGA results showed that the active aluminum oxide can improve the thermal stability of the composites. -- Highlights: ► Form-stable PA/active aluminum oxide composites as PCMs were prepared. ► Chemical structure, crystalloid phase and microstructure of composites were determined. ► Thermal properties and thermal stability of the composites were investigated. ► Expanded graphite can improve thermal conductivity of the composites.

Contribution of stable isotopes to the study of pharmacokinetics of magnesium salts; Apport des isotopes stables a l'etude de la pharmacocinetique de sels de magnesium

Energy Technology Data Exchange (ETDEWEB)

Benech, H

1999-05-28

The use of stable isotopes as labels is becoming an attractive tool for the study of magnesium behavior in humans. It has been used two stable isotopes of magnesium, {sup 25}Mg and {sup 26}Mg, to measure the absolute bioavailability of a pharmaceutical form of magnesium. (N.C.)

CmRBP50 protein phosphorylation is essential for assembly of a stable phloem-mobile high-affinity ribonucleoprotein complex.

Science.gov (United States)

Li, Pingfang; Ham, Byung-Kook; Lucas, William J

2011-07-01

RNA-binding proteins (RBPs) form ribonucleoprotein (RNP) complexes that play crucial roles in RNA processing for gene regulation. The angiosperm sieve tube system contains a unique population of transcripts, some of which function as long-distance signaling agents involved in regulating organ development. These phloem-mobile mRNAs are translocated as RNP complexes. One such complex is based on a phloem RBP named Cucurbita maxima RNA-binding protein 50 (CmRBP50), a member of the polypyrimidine track binding protein family. The core of this RNP complex contains six additional phloem proteins. Here, requirements for assembly of this CmRBP50 RNP complex are reported. Phosphorylation sites on CmRBP50 were mapped, and then coimmunoprecipitation and protein overlay studies established that the phosphoserine residues, located at the C terminus of CmRBP50, are critical for RNP complex assembly. In vitro pull-down experiments revealed that three phloem proteins, C. maxima phloem protein 16, C. maxima GTP-binding protein, and C. maxima phosphoinositide-specific phospholipase-like protein, bind directly with CmRBP50. This interaction required CmRBP50 phosphorylation. Gel mobility-shift assays demonstrated that assembly of the CmRBP50-based protein complex results in a system having enhanced binding affinity for phloem-mobile mRNAs carrying polypyrimidine track binding motifs. This property would be essential for effective long-distance translocation of bound mRNA to the target tissues.

CASPT2 study of inverse sandwich-type dinuclear Cr(I) and Fe(I) complexes of the dinitrogen molecule: significant differences in spin multiplicity and coordination structure between these two complexes.

Science.gov (United States)

Nakagaki, Masayuki; Sakaki, Shigeyoshi

2014-02-20

Inverse sandwich-type complexes (ISTCs), (μ-N2)[M(AIP)]2 (AIPH = (Z)-1-amino-3-imino-prop-1-ene; M = Cr and Fe), were investigated with the CASPT2 method. In the ISTC of Cr, the ground state takes a singlet spin multiplicity. However, the singlet to nonet spin states are close in energy to each other. The thermal average of effective magnetic moments (μeff) of these spin multiplicities is close to the experimental value. The η(2)-side-on coordination structure of N2 is calculated to be more stable than the η(1)-end-on coordination one. This is because the d-orbital of Cr forms a strong dπ-π* bonding interaction with the π* orbital of N2 in molecular plane. In the ISTC of Fe, on the other hand, the ground state takes a septet spin multiplicity, which agrees well with the experimentally reported μeff value. The η(1)-end-on structure of N2 is more stable than the η(2)-side-on structure. In the η(1)-end-on structure, two doubly occupied d-orbitals of Fe can form two dπ-π* bonding interactions. The negative spin density is found on the bridging N2 ligand in the Fe complex but is not in the Cr complex. All these interesting differences between ISTCs of Cr and Fe are discussed on the basis of the electronic structure and bonding nature.

A model for a stable coronal loop

International Nuclear Information System (INIS)

Hoven, G.V.; Chiuderi, C.; Giachetti, R.

1977-01-01

We present here a new plasma-physics model of a stable active-region arch which corresponds to the structure observed in the EUV. Pressure gradients are seen, so that the equilibrium magnetic field must depart from the force-free form valid in the surrounding corona. We take advantage of the data and of the approximate cylindrical symmetry to develop a modified form of the commonly assumed sheared-spiral structure. The dynamic MHD behavior of this new pressure/field model is then evaluated by the Newcomb criterion, taken from controlled-fusion physics, and the results show short-wavelength stability in a specific parameter range. Thus we demonstrate the possibility, for pressure profiles with widths of the order of the magnetic-field scale, that such arches can persist for reasonable periods. Finally, the spatial proportions and magnetic fields of a characteristic stable coronal loop are described

SV40 large T-p53 complex: evidence for the presence of two immunologically distinct forms of p53

International Nuclear Information System (INIS)

Milner, J.; Gamble, J.

1985-01-01

The transforming protein of SV40 is the large T antigen. Large T binds a cellular protein, p53, which is potentially oncogenic by virtue of its functional involvement in the control of cell proliferation. This raises the possibility that p53 may mediate, in part, the transforming function of SV40 large T. Two immunologically distinct forms of p53 have been identified in normal cells: the forms are cell-cycle dependent, one being restricted to nondividing cells (p53-Go) and the second to dividing cells (p53-G divided by). The authors have now dissociated and probed the multimeric complex of SV40 large T-p53 for the presence of immunologically distinct forms of p53. Here they present evidence for the presence of p53-Go and p53-G divided by complexed with SV40 large T

Complexometric determination: Part I - EDTA and complex formation with the Cu2+ ion

Directory of Open Access Journals (Sweden)

Rajković Miloš B.

2002-01-01

Full Text Available Compounds forming very stable complexes - chelates, have a wide field of application in analytical chemistry. The most famous group of these compounds are complexons. Complexons represent organic polyaminocarbonic acids as for example ethylenediaminetetraacetic acid (EDTA and its salts. The EDTA molecule has six coordinative sites. It is a hexadentate ligands i.e. it has two binding nitrogen atoms and four oxygen atoms from carboxyl groups and it forms complexes with almost all metal ions. EDTA as a tetraprotonic acid, H4Y disociates through four steps, yielding the ions HsY-, H2Y2-, HY3- and Y4-. Which of the EDTA forms will be encountered in a solution, depends on the pH. Due to the poor solubility of EDTA in pure water, as well as in most organic solvents, the disodium salt of EDTA Na2H2Y-2H2O, under the commercial name complexon III, is utilized for analytical determinations. In water, EDTA forms soluble, stabile chelate complexes with all cations, at the molar ratio 1:1, regardless of the charge of the metal ion. In contrast to other equilibria, which are mainly defined by Le Chatellier's principle, equilibria related to metal-EDTA complex formation are also dependent on the influence of the secondary equilibria of EDTA complex formation. Complexing reactions, which are equilibrium reactions, are simultaneously influenced by the following factors: solution pH and the presence of complexing agents which may also form a stabile complex with metal ions. The secondary reaction influence may be viewed and monitored through conditional stability constants. In the first part of the paper, the reaction of the formation of the Cu2+-ion complex with EDTA is analyzed beginning from the main reaction through various influences of secondary reactions on the complex Cu2+-EDTA: pH effect, complexation effect and hydrolysis effect. The equations are given for conditional stability constants, which include equilibrium reactions under actual conditions.

Complexes of vanadyl and uranyl ions with the chelating groups of humic matter

International Nuclear Information System (INIS)

Goncalves, M.L.S.; Mota, A.M.

1987-01-01

The uranyl and vanadyl complexes formed with salicylic, phthalic and 3,4-dihydroxybenzoic acids have been studied by potentiometry in order to determine the stability constants of the Msub(m) Lsub(n) species formed in solution, and the constants for hydrolysis and polymeric complexes, at 25.0 0 , in 0.10, 0.40 and 0.70M sodium perchlorate. MINIQUAD was used in process the data to find the best models for the species in solution, and calculate the formation constants. The uranyl-salicylic acid sytem was also studied by spectrophotometry and the program SQUAD used to process the data obtained. The best models for these systems show that co-ordination of the uranyl ion by carboxylate groups is easier than for the vanadyl ion, whereas the vanadyl ion seems to form more stable complexes with phenolate groups. Both oxo-cations seem to tend to hydrolyse rather than form complexes when the L:M ratios are greater than unity. Although the change in the constants with ionic strength is small, the activity coefficients of the salicylate and phthalate species have been calculated at ionic strengths 0.40 and 0.70M, along with the interaction parameters with Na + , from the stability constants found for the species ML and H 2 L, according to the Bronsted-Guggenheim expression. (author)

Contribution of stable isotopes to the study of pharmacokinetics of magnesium salts; Apport des isotopes stables a l'etude de la pharmacocinetique de sels de magnesium

Energy Technology Data Exchange (ETDEWEB)

Benech, H

1999-05-28

The use of stable isotopes as labels is becoming an attractive tool for the study of magnesium behavior in humans. It has been used two stable isotopes of magnesium, {sup 25}Mg and {sup 26}Mg, to measure the absolute bioavailability of a pharmaceutical form of magnesium. (N.C.)

STABLE ISOTOPE GEOCHEMISTRY OF MASSIVE ICE

Directory of Open Access Journals (Sweden)

Yurij K. Vasil’chuk

2016-01-01

Full Text Available The paper summarises stable-isotope research on massive ice in the Russian and North American Arctic, and includes the latest understanding of massive-ice formation. A new classification of massive-ice complexes is proposed, encompassing the range and variabilityof massive ice. It distinguishes two new categories of massive-ice complexes: homogeneousmassive-ice complexes have a similar structure, properties and genesis throughout, whereasheterogeneous massive-ice complexes vary spatially (in their structure and properties andgenetically within a locality and consist of two or more homogeneous massive-ice bodies.Analysis of pollen and spores in massive ice from Subarctic regions and from ice and snow cover of Arctic ice caps assists with interpretation of the origin of massive ice. Radiocarbon ages of massive ice and host sediments are considered together with isotope values of heavy oxygen and deuterium from massive ice plotted at a uniform scale in order to assist interpretation and correlation of the ice.

26 S proteasomes function as stable entities

DEFF Research Database (Denmark)

Hendil, Klavs B; Hartmann-Petersen, Rasmus; Tanaka, Keiji

2002-01-01

, shuttles between a free state and the 26-S proteasome, bringing substrate to the complex. However, S5a was not found in the free state in HeLa cells. Besides, all subunits in PA700, including S5a, exchanged at similar low rates. It therefore seems that 26-S proteasomes function as stable entities during...

Thermodynamics of U(VI) and Eu(III) complexation by unsaturated carboxylates

Energy Technology Data Exchange (ETDEWEB)

Rawat, Neetika; Bhattacharyya, A. [Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Tomar, B.S., E-mail: bstomar@barc.gov.in [Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Ghanty, T.K. [Theoretical Chemistry Section, Bhabha Atomic Research Centre, Mumbai 400085 (India); Manchanda, V.K. [Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

2011-05-10

Highlights: {yields} {Delta}H and log K determined for U(VI) and Eu(III) complexes with maleate and fumarate. {yields} log K and coordination environment of Eu(III) complexes has been studied by TRFS. {yields} Higher log K of U(VI) complexes than Eu(III) complexes is due to higher entropy. {yields} Plot of log K vs log K{sub P} suggest charge polarization in fumarate complexes. {yields} Ab initio calculations support charge polarization in fumarate complexes. - Abstract: The thermodynamic parameters ({Delta}G, {Delta}H and {Delta}S) of complexation of U(VI) and Eu(III) by unsaturated dicarboxylic acids, namely, maleic and fumaric acid, has been determined by potentiometric and microcalorimetric titrations at fixed ionic strength (I = 1.0 M) and temperature (298 K). The results show formation of 1:1 complexes by both the ligands with Eu(III). In the case of U(VI), maleate forms both 1:1 and 1:2 complexes, while only 1:1 complex was formed with fumarate. The fluorescence emission spectra of Eu(III)-dicarboxylate solutions at varying ligand to metal ratio were also used to obtain their stability constants. In addition, the fluorescence lifetimes reveal higher dehydration of Eu(III)-maleate compared to Eu(III)-fumarate which corroborates the {Delta}S values. The thermodynamic quantities suggest charge polarization effects in the case of U(VI) and Eu(III) complexes of fumarate, which is further corroborated by theoretical calculations. For the same ligand, U(VI) complexes were found to be more stable which was mainly due to higher entropy term.

Human orexin/hypocretin receptors form constitutive homo- and heteromeric complexes with each other and with human CB1 cannabinoid receptors

International Nuclear Information System (INIS)

Jäntti, Maria H.; Mandrika, Ilona; Kukkonen, Jyrki P.

2014-01-01

Highlights: • OX 1 and OX 2 orexin and CB 1 cannabinoid receptor dimerization was investigated. • Bioluminescence resonance energy transfer method was used. • All receptors readily formed constitutive homo- and heteromeric complexes. - Abstract: Human OX 1 orexin receptors have been shown to homodimerize and they have also been suggested to heterodimerize with CB 1 cannabinoid receptors. The latter has been suggested to be important for orexin receptor responses and trafficking. In this study, we wanted to assess the ability of the other combinations of receptors to also form similar complexes. Vectors for expression of human OX 1 , OX 2 and CB 1 receptors, C-terminally fused with either Renilla luciferase or GFP 2 green fluorescent protein variant, were generated. The constructs were transiently expressed in Chinese hamster ovary cells, and constitutive dimerization between the receptors was assessed by bioluminescence energy transfer (BRET). Orexin receptor subtypes readily formed homo- and hetero(di)mers, as suggested by significant BRET signals. CB 1 receptors formed homodimers, and they also heterodimerized with both orexin receptors. Interestingly, BRET efficiency was higher for homodimers than for almost all heterodimers. This is likely to be due to the geometry of the interaction; the putatively symmetric dimers may place the C-termini in a more suitable orientation in homomers. Fusion of luciferase to an orexin receptor and GFP 2 to CB 1 produced more effective BRET than the opposite fusions, also suggesting differences in geometry. Similar was seen for the OX 1 –OX 2 interaction. In conclusion, orexin receptors have a significant propensity to make homo- and heterodi-/oligomeric complexes. However, it is unclear whether this affects their signaling. As orexin receptors efficiently signal via endocannabinoid production to CB 1 receptors, dimerization could be an effective way of forming signal complexes with optimal cannabinoid concentrations

Mannan-binding protein forms complexes with alpha-2-macroglobulin. A protein model for the interaction

DEFF Research Database (Denmark)

Storgaard, P; Holm Nielsen, E; Skriver, E

1995-01-01

We report that alpha-2-macroglobulin (alpha 2M) can form complexes with a high molecular weight porcine mannan-binding protein (pMBP-28). The alpha 2M/pMBP-28 complexes was isolated by PEG-precipitation and affinity chromatography on mannan-Sepharose, protein A-Sepharose and anti-IgM Sepharose......-PAGE, which reacted with antibodies against alpha 2M and pMBP-28, respectively, in Western blotting. Furthermore, alpha 2M/pMBP-28 complexes were demonstrated by electron microscopy. Fractionation of pMBP-containing D-mannose eluate from mannan-Sepharose on Superose 6 showed two protein peaks which reacted...... with anti-C1 s antibodies in ELISA, one of about 650-800 kDa, which in addition contained pMBP-28 and anti-alpha 2M reactive material, the other with an M(r) of 100-150 kDa. The latter peak revealed rhomboid molecules (7 x 15 nm) in the electron microscope and a 67 kDa band in SDS-PAGE under reducing...

Synthesis of several tetraaza macrocyclic amine ligands and the biodistribution of their Tc-complexes

International Nuclear Information System (INIS)

Ketring, A.R.

1982-01-01

Several macrocyclic tetraaza ligands were synthesized and their /sup 99m/Tc-complexes prepared. The biological distribution of these complexes was examined to determine their possible utility as radiodiagnostic agents. The simplest of the macrocyclic tetraaza ligands studied, cyclam, forms a very stable cationic complex with Tc when pertechnetate is reduced with stannous ion in an aqueous solution of the ligand. When injected intravenously into mice Tc-cyclam was excreted predominantly by the urinary system. Derivatives of cyclam which were synthesized contained aromatic or aliphatic substituents and formed more lipophilic complexes with Tc. The complexes were formed in high yield as determined by paper chromatography, thin layer chromatography, electrophoresis and/or high performance liquid chromatography. Relative lipophilicities were determined for the complexes by octanol-to-water extractions. Animal studies using mice indicated there was an inverse relationship between the octanol-to-water extraction ratio and urinary excretion. Two of the complexes having relatively high octanol-to-water extraction ratios were significantly excreted by the hepatobiliary system with localization in the gall bladder. The complex having the highest octanol-to-water ratio was not excreted significantly by the hepatobiliary system, but cleared very slowly from the blood and localized in the liver, lungs, spleen and to some extent the heart. Derivatization of cyclam can be performed without greatly reducing its ability to complex Tc but greatly influencing the biological distribution of its Tc complex. This indicates that there is a potential for preparing radiodiagnostic agents using macrocyclic tetraaza ligands

Crystallization, data collection and processing of the chymotrypsin–BTCI–trypsin ternary complex

Energy Technology Data Exchange (ETDEWEB)

Esteves, Gisele Ferreira; Teles, Rozeni Chagas Lima; Cavalcante, Nayara Silva; Neves, David; Ventura, Manuel Mateus [Laboratório de Biofísica, Instituto de Ciências Biológicas, Universidade de Brasília, 70910-900 Brasília-DF (Brazil); Barbosa, João Alexandre Ribeiro Gonçalves, E-mail: joao@lnls.br [Center for Structural Molecular Biology (CeBiME), Brazilian Synchrotron Light Laboratory (LNLS), CP 6192, 13083-970 Campinas-SP (Brazil); Freitas, Sonia Maria de, E-mail: joao@lnls.br [Laboratório de Biofísica, Instituto de Ciências Biológicas, Universidade de Brasília, 70910-900 Brasília-DF (Brazil)

2007-12-01

A ternary complex of the proteinase inhibitor (BTCI) with trypsin and chymotrypsin was crystallized and its crystal structure was solved by molecular replacement. A ternary complex of the black-eyed pea trypsin and chymotrypsin inhibitor (BTCI) with trypsin and chymotrypsin was crystallized by the sitting-drop vapour-diffusion method with 0.1 M HEPES pH 7.5, 10%(w/v) polyethylene glycol 6000 and 5%(v/v) 2-methyl-2,4-pentanediol as precipitant. BTCI is a small protein with 83 amino-acid residues isolated from Vigna unguiculata seeds and is able to inhibit trypsin and chymotrypsin simultaneously by forming a stable ternary complex. X-ray data were collected from a single crystal of the trypsin–BTCI–chymotrypsin ternary complex to 2.7 Å resolution under cryogenic conditions. The structure of the ternary complex was solved by molecular replacement using the crystal structures of the BTCI–trypsin binary complex (PDB code) and chymotrypsin (PDB code) as search models.

Crystallization, data collection and processing of the chymotrypsin–BTCI–trypsin ternary complex

International Nuclear Information System (INIS)

Esteves, Gisele Ferreira; Teles, Rozeni Chagas Lima; Cavalcante, Nayara Silva; Neves, David; Ventura, Manuel Mateus; Barbosa, João Alexandre Ribeiro Gonçalves; Freitas, Sonia Maria de

2007-01-01

A ternary complex of the proteinase inhibitor (BTCI) with trypsin and chymotrypsin was crystallized and its crystal structure was solved by molecular replacement. A ternary complex of the black-eyed pea trypsin and chymotrypsin inhibitor (BTCI) with trypsin and chymotrypsin was crystallized by the sitting-drop vapour-diffusion method with 0.1 M HEPES pH 7.5, 10%(w/v) polyethylene glycol 6000 and 5%(v/v) 2-methyl-2,4-pentanediol as precipitant. BTCI is a small protein with 83 amino-acid residues isolated from Vigna unguiculata seeds and is able to inhibit trypsin and chymotrypsin simultaneously by forming a stable ternary complex. X-ray data were collected from a single crystal of the trypsin–BTCI–chymotrypsin ternary complex to 2.7 Å resolution under cryogenic conditions. The structure of the ternary complex was solved by molecular replacement using the crystal structures of the BTCI–trypsin binary complex (PDB code) and chymotrypsin (PDB code) as search models

The stable nonequilibrium state of bicarbonate aqueous systems

Science.gov (United States)

Voeikov, V. L.; Vilenskaya, N. D.; Ha, Do Minh; Malyshenko, S. I.; Buravleva, E. V.; Yablonskaya, O. I.; Timofeev, K. N.

2012-09-01

Data obtained by electron paramagnetic resonance (EPR) and chemiluminescence analysis indicate that in aqueous solutions of bicarbonates, superoxide radical and other reactive oxygen species (ROS) are constantly produced. The stationary level of the superoxide radical is found to increase when a solution is illuminated. Reactions involving ROS are shown to be accompanied by the generation of electron excitation energy, keeping bicarbonate solutions in a stable nonequilibrium state. The system can emit part of this energy. Variations in emitting activity are found to correlate with variations in the cosmophysical factors. The emitting activity of solutions is found to vary in the presence of low and ultralow concentrations of hydrated fullerenes. It is noted that the phenomenon of spontaneous charge separation in aqueous systems (G. H. Pollack) could play a role in maintaining a stable nonequilibrium state in bicarbonate systems where the reactions with ROS participation are catalyzed by forms of carbonate. It is concluded that the abovementioned properties of bicarbonate aqueous systems most likely keep living matter whose structural basis is formed by these systems in a stable excited state, thereby making it highly sensitive to the action of external factors with low and ultralow intensities.

Complexation between carrageenan and methylene blue for sensor design

Science.gov (United States)

Ling, Yew Pei; Heng, Lee Yook

2013-11-01

Theoretical studies on the methylene blue (MB)-carrageenans complexation at solution and solid states have been carried out via ultraviolet spectrophotoscopy and reflectometry methods. The equilibrium constant (Ka) of the MBcarrageenans complexation follows the order of Iota > Lambda > Kappa carrageenans, which indicated Iota-carrageenan forms a stable complex. MB-carrageenan complexation reaction showed decrease in Ka value from 210.71 ppm-1 to 114.57 ppm-1 when the reaction temperature increased from 298 K to 323 K. Le Chatelier's principle and mass action law explained that the MB-carrageenan complexation was an exothermic reaction (ΔH=-18.54 kJmol-1) that release heat. Thus MB-carrageenan complex was less stable at high temperature and tend to dissociate into free MB and carrageenan molecules. It was also supported by the van't Hoff equation. The reaction is a spontaneous process (ΔG=-13.23 kJmol-1) where the randomness of the molecules reduced (ΔS=-17.83 Jmol-1K-1) due to complexation. Besides, linear regression of the concentration and absorption of the MB-carrageenan reaction obeys the Beer Lambert law, which elucidated that the complexation process was not affected by any concentration dependent factors such as aggregation and self-quenching. Moreover, linear Benesi Hilderbrend plot revealed that the interaction between MB and carrageenan was a reversible and stoichiometric reaction with 1:1 ratio. However, the molar extinction coefficient (ɛ) and molar adsorption coefficient (μa) of the MB-carrageenan complex were lower compared to free MB, described that the complex was less adsorptive. The sensor constructed based on these theoretical investigations showed response behavior that was similar with solution test as both have attraction for carrageenans in the sequence of Iota-, Lambda-, Kappa- carrageenans. Likewise, carrageenan sensor was more selective towards Iota-carrageenan than to Lambda- and Kappa-carrageenans, and no response observed when

Molecular Mechanisms of the Cytotoxicity of Human α-Lactalbumin Made Lethal to Tumor Cells (HAMLET) and Other Protein-Oleic Acid Complexes*

Science.gov (United States)

Nakamura, Takashi; Aizawa, Tomoyasu; Kariya, Ryusho; Okada, Seiji; Demura, Makoto; Kawano, Keiichi; Makabe, Koki; Kuwajima, Kunihiro

2013-01-01

Although HAMLET (human α-lactalbumin made lethal to tumor cells), a complex formed by human α-lactalbumin and oleic acid, has a unique apoptotic activity for the selective killing of tumor cells, the molecular mechanisms of expression of the HAMLET activity are not well understood. Therefore, we studied the molecular properties of HAMLET and its goat counterpart, GAMLET (goat α-lactalbumin made lethal to tumor cells), by pulse field gradient NMR and 920-MHz two-dimensional NMR techniques. We also examined the expression of HAMLET-like activities of complexes between oleic acid and other proteins that form a stable molten globule state. We observed that both HAMLET and GAMLET at pH 7.5 were heterogeneous, composed of the native protein, the monomeric molten globule-like state, and the oligomeric species. At pH 2.0 and 50 °C, HAMLET and GAMLET appeared in the monomeric state, and we identified the oleic acid-binding site in the complexes by two-dimensional NMR. Rather surprisingly, the binding site thus identified was markedly different between HAMLET and GAMLET. Furthermore, canine milk lysozyme, apo-myoglobin, and β2-microglobulin all formed the HAMLET-like complex with the anti-tumor activity, when the protein was treated with oleic acid under conditions in which their molten globule states were stable. From these results, we conclude that the protein portion of HAMLET, GAMLET, and the other HAMLET-like protein-oleic acid complexes is not the origin of their cytotoxicity to tumor cells and that the protein portion of these complexes plays a role in the delivery of cytotoxic oleic acid molecules into tumor cells across the cell membrane. PMID:23580643

Molecular mechanisms of the cytotoxicity of human α-lactalbumin made lethal to tumor cells (HAMLET) and other protein-oleic acid complexes.

Science.gov (United States)

Nakamura, Takashi; Aizawa, Tomoyasu; Kariya, Ryusho; Okada, Seiji; Demura, Makoto; Kawano, Keiichi; Makabe, Koki; Kuwajima, Kunihiro

2013-05-17

Although HAMLET (human α-lactalbumin made lethal to tumor cells), a complex formed by human α-lactalbumin and oleic acid, has a unique apoptotic activity for the selective killing of tumor cells, the molecular mechanisms of expression of the HAMLET activity are not well understood. Therefore, we studied the molecular properties of HAMLET and its goat counterpart, GAMLET (goat α-lactalbumin made lethal to tumor cells), by pulse field gradient NMR and 920-MHz two-dimensional NMR techniques. We also examined the expression of HAMLET-like activities of complexes between oleic acid and other proteins that form a stable molten globule state. We observed that both HAMLET and GAMLET at pH 7.5 were heterogeneous, composed of the native protein, the monomeric molten globule-like state, and the oligomeric species. At pH 2.0 and 50 °C, HAMLET and GAMLET appeared in the monomeric state, and we identified the oleic acid-binding site in the complexes by two-dimensional NMR. Rather surprisingly, the binding site thus identified was markedly different between HAMLET and GAMLET. Furthermore, canine milk lysozyme, apo-myoglobin, and β2-microglobulin all formed the HAMLET-like complex with the anti-tumor activity, when the protein was treated with oleic acid under conditions in which their molten globule states were stable. From these results, we conclude that the protein portion of HAMLET, GAMLET, and the other HAMLET-like protein-oleic acid complexes is not the origin of their cytotoxicity to tumor cells and that the protein portion of these complexes plays a role in the delivery of cytotoxic oleic acid molecules into tumor cells across the cell membrane.

The Effect of Focus on Form and Task Complexity on L2 Learners' Oral Task Performance

Science.gov (United States)

Salimi, Asghar

2015-01-01

Second Language learners' oral task performance has been one of interesting and research generating areas of investigations in the field of second language acquisition specially, task-based language teaching and learning. The main purpose of the present study is to investigate the effect of focus on form and task complexity on L2 learners' oral…

Tetra- and hexavalent uranium forms bidentate-mononuclear complexes with particulate organic matter in a naturally uranium-enriched peatland

DEFF Research Database (Denmark)

Mikutta, Christian; Langner, Peggy; Bargar, John R.

2016-01-01

Peatlands frequently serve as efficient biogeochemical traps for U. Mechanisms of U immobilization in these organic matter-dominated environments may encompass the precipitation of U-bearing mineral(oid)s and the complexation of U by a vast range of (in)organic surfaces. The objective of this work...... of bidentate-mononuclear U(IV/VI) complexes with carboxyl groups. We neither found evidence for U shells at ∼3.9 Å, indicative of mineral-associated U or multinuclear U(IV) species, nor for a substantial P/Fe coordination of U. Our data indicates that U(IV/VI) complexation by natural organic matter prevents...... the precipitation of U minerals as well as U complexation by Fe/Mn phases at our field site, and suggests that organically complexed U(IV) is formed via reduction of organic matter-bound U(VI)....

Variational energy principle for compressible, baroclinic flow. 2: Free-energy form of Hamilton's principle

Science.gov (United States)

Schmid, L. A.

1977-01-01

The first and second variations are calculated for the irreducible form of Hamilton's Principle that involves the minimum number of dependent variables necessary to describe the kinetmatics and thermodynamics of inviscid, compressible, baroclinic flow in a specified gravitational field. The form of the second variation shows that, in the neighborhood of a stationary point that corresponds to physically stable flow, the action integral is a complex saddle surface in parameter space. There exists a form of Hamilton's Principle for which a direct solution of a flow problem is possible. This second form is related to the first by a Friedrichs transformation of the thermodynamic variables. This introduces an extra dependent variable, but the first and second variations are shown to have direct physical significance, namely they are equal to the free energy of fluctuations about the equilibrium flow that satisfies the equations of motion. If this equilibrium flow is physically stable, and if a very weak second order integral constraint on the correlation between the fluctuations of otherwise independent variables is satisfied, then the second variation of the action integral for this free energy form of Hamilton's Principle is positive-definite, so the action integral is a minimum, and can serve as the basis for a direct trail and error solution. The second order integral constraint states that the unavailable energy must be maximum at equilibrium, i.e. the fluctuations must be so correlated as to produce a second order decrease in the total unavailable energy.

MECHANISMS OF THE COMPLEX FORMATION BY d-METALS ON POROUS SUPPORTS AND THE CATALYTIC ACTIVITY OF THE FORMED COMPLEXES IN REDOX REACTIONS

Directory of Open Access Journals (Sweden)

T. L. Rakitskaya

2015-11-01

Full Text Available The catalytic activity of supported complexes of d metals in redox reactions with participation of gaseous toxicants, PH3, CO, O3, and SO2, depends on their composition. Owing to the variety of physicochemical and structural-adsorption properties of available supports, their influence on complex formation processes, the composition and catalytic activity of metal complexes anchored on them varies over a wide range. The metal complex formation on sup-ports with weak ion-exchanging properties is similar to that in aqueous solutions. In this case, the support role mainly adds up to the ability to reduce the activity of water adsorbed on them. The interaction between a metal complex and a support surface occurs through adsorbed water molecules. Such supports can also affect complex formation processes owing to protolytic reactions on account of acidic properties of sorbents used as supports. The catalytic activity of metal complexes supported on polyphase natural sorbents considerably depends on their phase relationship. In the case of supports with the nonsimple structure and pronounced ion-exchanging properties, for instance, zeolites and laminar silicates, it is necessary to take into account the variety of places where metal ions can be located. Such location places determine distinctions in the coordination environment of the metal ions and the strength of their bonding with surface adsorption sites and, therefore, the catalytic activity of surface complexes formed by theses metal ions. Because of the energy surface inhomogeneity, it is important to determine a relationship between the strength of a metal complex bonding with a support surface and its catalytic activity. For example, bimetallic complexes are catalytically active in the reactions of oxidation of the above gaseous toxicants. In particular, in the case of carbon monoxide oxidation, the most catalytic activity is shown by palladium-copper complexes in which copper(II is strongly

Stable carbon isotope fractionation of organic cyst-forming dinoflagellates: Evaluating the potential for a CO2 proxy

Science.gov (United States)

Hoins, Mirja; Van de Waal, Dedmer B.; Eberlein, Tim; Reichart, Gert-Jan; Rost, Björn; Sluijs, Appy

2015-07-01

Over the past decades, significant progress has been made regarding the quantification and mechanistic understanding of stable carbon isotope fractionation (13C fractionation) in photosynthetic unicellular organisms in response to changes in the partial pressure of atmospheric CO2 (pCO2). However, hardly any data is available for organic cyst-forming dinoflagellates while this is an ecologically important group with a unique fossil record. We performed dilute batch experiments with four harmful dinoflagellate species known for their ability to form organic cysts: Alexandrium tamarense, Scrippsiella trochoidea, Gonyaulax spinifera and Protoceratium reticulatum. Cells were grown at a range of dissolved CO2 concentrations characterizing past, modern and projected future values (∼5-50 μmol L-1), representing atmospheric pCO2 of 180, 380, 800 and 1200 μatm. In all tested species, 13C fractionation depends on CO2 with a slope of up to 0.17‰ (μmol L)-1. Even more consistent correlations were found between 13C fractionation and the combined effects of particulate organic carbon quota (POC quota; pg C cell-1) and CO2. Carbon isotope fractionation as well as its response to CO2 is species-specific. These results may be interpreted as a first step towards a proxy for past pCO2 based on carbon isotope ratios of fossil organic dinoflagellate cysts. However, additional culture experiments focusing on environmental variables other than pCO2, physiological underpinning of the recorded response, testing for possible offsets in 13C values between cells and cysts, as well as field calibration studies are required to establish a reliable proxy.

Contribution of stable isotopes to the study of pharmacokinetics of magnesium salts

International Nuclear Information System (INIS)

Benech, H.

1999-01-01

The use of stable isotopes as labels is becoming an attractive tool for the study of magnesium behavior in humans. It has been used two stable isotopes of magnesium, 25 Mg and 26 Mg, to measure the absolute bioavailability of a pharmaceutical form of magnesium. (N.C.)

New Spectrophotometric and Conductometric Methods for Macrolide Antibiotics Determination in Pure and Pharmaceutical Dosage Forms Using Rose Bengal

Directory of Open Access Journals (Sweden)

Rania A. Sayed

2013-01-01

Full Text Available Two Simple, accurate, precise, and rapid spectrophotometric and conductometric methods were developed for the estimation of erythromycin thiocyanate (I, clarithromycin (II, and azithromycin dihydrate (III in both pure and pharmaceutical dosage forms. The spectrophotometric procedure depends on the reaction of rose bengal and copper with the cited drugs to form stable ternary complexes which are extractable with methylene chloride, and the absorbances were measured at 558, 557, and 560 nm for (I, (II, and (III, respectively. The conductometric method depends on the formation of an ion-pair complex between the studied drug and rose bengal. For the spectrophotometric method, Beer's law was obeyed. The correlation coefficient ( for the studied drugs was found to be 0.9999. The molar absorptivity (, Sandell’s sensitivity, limit of detection (LOD, and limit of quantification (LOQ were also calculated. The proposed methods were successfully applied for the determination of certain pharmaceutical dosage forms containing the studied drugs

The relationship between fractional flow reserve, platelet reactivity and platelet leukocyte complexes in stable coronary artery disease

NARCIS (Netherlands)

Sels, J.W.E.M.; Rutten, B.; Holten, van T.C.; Hillaert, M.A.K.; Waltenberger, J.; Pijls, N.H.J.; Pasterkamp, G.; Groot, de P.G.; Roest, M.

2013-01-01

Background: The presence of stenoses that significantly impair blood flow and cause myocardial ischemia negatively affects prognosis of patients with stable coronary artery disease. Altered platelet reactivity has been associated with impaired prognosis of stable coronary artery disease. Platelets

Utilizing whey protein isolate and polysaccharide complexes to stabilize aerated dairy gels.

Science.gov (United States)

O'Chiu, Emily; Vardhanabhuti, Bongkosh

2017-05-01

Heated soluble complexes of whey protein isolate (WPI) with polysaccharides may be used to modify the properties of aerated dairy gels, which could be formulated into novel-textured high-protein desserts. The objective of this study was to determine the effect of polysaccharide charge density and concentration within a WPI-polysaccharide complex on the physical properties of aerated gels. Three polysaccharides having different degrees of charge density were chosen: low-methoxyl pectin, high-methoxyl type D pectin, and guar gum. Heated complexes were prepared by heating the mixed dispersions (8% protein, 0 to 1% polysaccharide) at pH 7. To form aerated gels, 2% glucono-δ-lactone was added to the dispersions of skim milk powder and heated complex and foam was generated by whipping with a handheld frother. The foam set into a gel as the glucono-δ-lactone acidified to a final pH of 4.5. The aerated gels were evaluated for overrun, drainage, gel strength, and viscoelastic properties. Without heated complexes, stable aerated gels could not be formed. Overrun of aerated gel decreased (up to 73%) as polysaccharide concentration increased from 0.105 to 0.315% due to increased viscosity, which limited air incorporation. A negative relationship was found between percent drainage and dispersion viscosity. However, plotting of drainage against dispersion viscosity separated by polysaccharide type revealed that drainage decreased most in samples with high-charge-density, low-methoxyl pectin followed by those with low-charge-density, high-methoxyl type D pectin. Aerated gels with guar gum (no charge) did not show improvement to stability. Rheological results showed no significant difference in gelation time among samples; therefore, stronger interactions between WPI and high-charge-density polysaccharide were likely responsible for increased stability. Stable dairy aerated gels can be created from WPI-polysaccharide complexes. High-charge-density polysaccharides, at

Local Search Approaches in Stable Matching Problems

Directory of Open Access Journals (Sweden)

Toby Walsh

2013-10-01

Full Text Available The stable marriage (SM problem has a wide variety of practical applications, ranging from matching resident doctors to hospitals, to matching students to schools or, more generally, to any two-sided market. In the classical formulation, n men and n women express their preferences (via a strict total order over the members of the other sex. Solving an SM problem means finding a stable marriage where stability is an envy-free notion: no man and woman who are not married to each other would both prefer each other to their partners or to being single. We consider both the classical stable marriage problem and one of its useful variations (denoted SMTI (Stable Marriage with Ties and Incomplete lists where the men and women express their preferences in the form of an incomplete preference list with ties over a subset of the members of the other sex. Matchings are permitted only with people who appear in these preference lists, and we try to find a stable matching that marries as many people as possible. Whilst the SM problem is polynomial to solve, the SMTI problem is NP-hard. We propose to tackle both problems via a local search approach, which exploits properties of the problems to reduce the size of the neighborhood and to make local moves efficiently. We empirically evaluate our algorithm for SM problems by measuring its runtime behavior and its ability to sample the lattice of all possible stable marriages. We evaluate our algorithm for SMTI problems in terms of both its runtime behavior and its ability to find a maximum cardinality stable marriage. Experimental results suggest that for SM problems, the number of steps of our algorithm grows only as O(n log(n, and that it samples very well the set of all stable marriages. It is thus a fair and efficient approach to generate stable marriages. Furthermore, our approach for SMTI problems is able to solve large problems, quickly returning stable matchings of large and often optimal size, despite the

The promyelocytic leukemia gene product (PML) forms stable complexes with the retinoblastoma protein

DEFF Research Database (Denmark)

Alcalay, M; Tomassoni, L; Colombo, E

1998-01-01

PML is a nuclear protein with growth-suppressive properties originally identified in the context of the PML-retinoic acid receptor alpha (RAR alpha) fusion protein of acute promyelocytic leukemia. PML localizes within distinct nuclear structures, called nuclear bodies, which are disrupted by the ...

An AAA-DDD triply hydrogen-bonded complex easily accessible for supramolecular polymers.

Science.gov (United States)

Han, Yi-Fei; Chen, Wen-Qiang; Wang, Hong-Bo; Yuan, Ying-Xue; Wu, Na-Na; Song, Xiang-Zhi; Yang, Lan

2014-12-15

For a complementary hydrogen-bonded complex, when every hydrogen-bond acceptor is on one side and every hydrogen-bond donor is on the other, all secondary interactions are attractive and the complex is highly stable. AAA-DDD (A=acceptor, D=donor) is considered to be the most stable among triply hydrogen-bonded sequences. The easily synthesized and further derivatized AAA-DDD system is very desirable for hydrogen-bonded functional materials. In this case, AAA and DDD, starting from 4-methoxybenzaldehyde, were synthesized with the Hantzsch pyridine synthesis and Friedländer annulation reaction. The association constant determined by fluorescence titration in chloroform at room temperature is 2.09×10(7)  M(-1) . The AAA and DDD components are not coplanar, but form a V shape in the solid state. Supramolecular polymers based on AAA-DDD triply hydrogen bonded have also been developed. This work may make AAA-DDD triply hydrogen-bonded sequences easily accessible for stimuli-responsive materials. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Biodegradation of metal citrate complexes and implications for toxic-metal mobility

International Nuclear Information System (INIS)

Francis, A.J.; Dodge, C.J.; Gillow, J.B.

1992-01-01

The presence of synthetic and naturally occurring chelating agents in nuclear and toxic-metal wastes is a major concern because of their potential to enhance mobilization of metal ions away from the disposal sites. Of particular interest is citric acid, which is present in low-level and transuranic radioactive wastes and in domestic and industrial wastes (as washing fluids, for instance), as well as being found naturally. Citrate ions form multidentate, stable complexes with a variety of toxic metals and radionuclides; but biodegradation of these complexes, precipitating the metal ions as insoluble hydroxides, oxides or other salts, may retard migration. Here we report a study of the biodegradation of citrate complexes of Ca, Fe(II), Fe(III), Cd, Cu, Ni, Pb and U. Several of these complexes were not readily degraded by bacteria, and the biodegradability depended on the chemical nature of the complex, not on the toxicity of the metal to the bacteria. This resistance to biodegradation implies that citrate complexation may play an important part in migration of these hazardous wastes. (author)

Collective almost synchronisation in complex networks.

Science.gov (United States)

Baptista, Murilo S; Ren, Hai-Peng; Swarts, Johen C M; Carareto, Rodrigo; Nijmeijer, Henk; Grebogi, Celso

2012-01-01

This work introduces the phenomenon of Collective Almost Synchronisation (CAS), which describes a universal way of how patterns can appear in complex networks for small coupling strengths. The CAS phenomenon appears due to the existence of an approximately constant local mean field and is characterised by having nodes with trajectories evolving around periodic stable orbits. Common notion based on statistical knowledge would lead one to interpret the appearance of a local constant mean field as a consequence of the fact that the behaviour of each node is not correlated to the behaviours of the others. Contrary to this common notion, we show that various well known weaker forms of synchronisation (almost, time-lag, phase synchronisation, and generalised synchronisation) appear as a result of the onset of an almost constant local mean field. If the memory is formed in a brain by minimising the coupling strength among neurons and maximising the number of possible patterns, then the CAS phenomenon is a plausible explanation for it.

The cellular transcription factor CREB corresponds to activating transcription factor 47 (ATF-47) and forms complexes with a group of polypeptides related to ATF-43.

Science.gov (United States)

Hurst, H C; Masson, N; Jones, N C; Lee, K A

1990-12-01

Promoter elements containing the sequence motif CGTCA are important for a variety of inducible responses at the transcriptional level. Multiple cellular factors specifically bind to these elements and are encoded by a multigene family. Among these factors, polypeptides termed activating transcription factor 43 (ATF-43) and ATF-47 have been purified from HeLa cells and a factor referred to as cyclic AMP response element-binding protein (CREB) has been isolated from PC12 cells and rat brain. We demonstrated that CREB and ATF-47 are identical and that CREB and ATF-43 form protein-protein complexes. We also found that the cis requirements for stable DNA binding by ATF-43 and CREB are different. Using antibodies to ATF-43 we have identified a group of polypeptides (ATF-43) in the size range from 40 to 43 kDa. ATF-43 polypeptides are related by their reactivity with anti-ATF-43, DNA-binding specificity, complex formation with CREB, heat stability, and phosphorylation by protein kinase A. Certain cell types vary in their ATF-43 complement, suggesting that CREB activity is modulated in a cell-type-specific manner through interaction with ATF-43. ATF-43 polypeptides do not appear simply to correspond to the gene products of the ATF multigene family, suggesting that the size of the ATF family at the protein level is even larger than predicted from cDNA-cloning studies.

Phase solubility, 1H NMR and molecular modelling studies of bupivacaine hydrochloride complexation with different cyclodextrin derivates

Science.gov (United States)

Jug, Mario; Mennini, Natascia; Melani, Fabrizio; Maestrelli, Francesca; Mura, Paola

2010-11-01

A novel method, which simultaneously exploits experimental (NMR) and theoretically calculated data obtained by a molecular modelling technique, was proposed, to obtain deeper insight into inclusion geometry and possible stereoselective binding of bupivacaine hydrochloride with selected cyclodextrin derivatives. Sulphobuthylether-β-cyclodextrin and water soluble polymeric β-cyclodextrin demonstrated to be the best complexing agents for the drug, resulting in formation of the most stable inclusion complexes with the highest increase in aqueous drug solubility. The drug-carrier binding modes with these cyclodextrins and phenomena which may be directly related to the higher stability and better aqueous solubility of complexes formed were discussed in details.

The Fanconi anemia protein FANCF forms a nuclear complex with FANCA, FANCC and FANCG.

Science.gov (United States)

de Winter, J P; van der Weel, L; de Groot, J; Stone, S; Waisfisz, Q; Arwert, F; Scheper, R J; Kruyt, F A; Hoatlin, M E; Joenje, H

2000-11-01

Fanconi anemia (FA) is a chromosomal instability syndrome associated with a strong predisposition to cancer, particularly acute myeloid leukemia and squamous cell carcinoma. At the cellular level, FA is characterized by spontaneous chromosomal breakage and a unique hypersensitivity to DNA cross-linking agents. Complementation analysis has indicated that at least seven distinct genes are involved in the pathogenesis of FA. Despite the identification of four of these genes (FANCA, FANCC, FANCF and FANCG), the nature of the 'FA pathway' has remained enigmatic, as the FA proteins lack sequence homologies or motifs that could point to a molecular function. To further define this pathway, we studied the subcellular localizations and mutual interactions of the FA proteins, including the recently identified FANCF protein, in human lymphoblasts. FANCF was found predominantly in the nucleus, where it complexes with FANCA, FANCC and FANCG. These interactions were detected in wild-type and FA-D lymphoblasts, but not in lymphoblasts of other FA complementation groups. This implies that each of the FA proteins, except FANCD, is required for these complexes to form. Similarly, we show that the interaction between FANCA and FANCC is restricted to wild-type and FA-D cells. Furthermore, we document the subcellular localization of FANCA and the FANCA/FANCG complex in all FA complementation groups. Our results, along with published data, culminate in a model in which a multi-protein FA complex serves a nuclear function to maintain genomic integrity.

A comparison of outcomes involving highly cohesive, form-stable breast implants from two manufacturers in patients undergoing primary breast augmentation.

Science.gov (United States)

Jewell, Mark L; Jewell, James L

2010-01-01

Although there have been reports of single-surgeon outcomes with highly cohesive, form-stable silicone gel implants in women undergoing primary breast augmentation, there has been only one study published that compares the outcomes between the Allergan 410 and the Mentor CPG devices. The goal of the study is to compare outcomes in each cohort and to determine if quality systems and processes would have an impact on lowering the surgical revision rate, as compared to published reports for round gel implants and form-stable implants. Patients selected for the study were required to meet predefined inclusion criteria and general indications for breast augmentation. All subjects were treated uniformly with extensive informed consent prior to surgery. The entire process of breast augmentation (patient assessment, informed consent, the surgical procedure itself and postoperative instructions) was identical between the two groups. Patients were not randomized, as the studies did not start at the same time. The process for management of each patient was based on adaptation of the Toyota Production System and Lean Manufacturing, with emphasis on achieving operational excellence in the use of planning templates for surgery, including accurate management of patient expectations regarding size outcome. Outcomes data included physical breast measurements, quality of life metrics, and patient/surgeon satisfaction assessment. Adverse events were compared against published data for breast implants. Follow-up ranged between 20-77 months (Allergan 410) and 16-77 months (Mentor CPG). The outcome data indicate that these devices produce natural-appearing breasts with extremely low aggregate reoperation rate (4.2%). Only 0.8% of the reoperations were attributable to surgeon-related factors. There were no reoperations to correct mismanaged size expectations during the course of each study. There were 13 pregnancies and no difficulties with lactation were reported. Rippling (lateral

Enhanced splicing correction effect by an oligo-aspartic acid-PNA conjugate and cationic carrier complexes.

Science.gov (United States)

Bae, Yun Mi; Kim, Myung Hee; Yu, Gwang Sig; Um, Bong Ho; Park, Hee Kyung; Lee, Hyun-il; Lee, Kang Taek; Suh, Yung Doug; Choi, Joon Sig

2014-02-10

Peptide nucleic acids (PNAs) are synthetic structural analogues of DNA and RNA. They recognize specific cellular nucleic acid sequences and form stable complexes with complementary DNA or RNA. Here, we designed an oligo-aspartic acid-PNA conjugate and showed its enhanced delivery into cells with high gene correction efficiency using conventional cationic carriers, such as polyethylenimine (PEI) and Lipofectamine 2000. The negatively charged oligo-aspartic acid-PNA (Asp(n)-PNA) formed complexes with PEI and Lipofectamine, and the resulting Asp(n)-PNA/PEI and Asp(n)-PNA/Lipofectamine complexes were introduced into cells. We observed significantly enhanced cellular uptake of Asp(n)-PNA by cationic carriers and detected an active splicing correction effect even at nanomolar concentrations. We found that the splicing correction efficiency of the complex depended on the kind of the cationic carriers and on the number of repeating aspartic acid units. By enhancing the cellular uptake efficiency of PNAs, these results may provide a novel platform technology of PNAs as bioactive substances for their biological and therapeutic applications. Copyright © 2013 Elsevier B.V. All rights reserved.

Complex-forming capacity of some biologically active imidazoles

Energy Technology Data Exchange (ETDEWEB)

Lenarcik, B; Wisniewski, M

1983-01-01

By using the potentiometric and spectrophotometric methods, formation of Co(2), Cu(2), Zn(2), Ni(2) and Cd(2) complexes of (3S-cis)-3-ethyl-dihydro-4-((1-methyl-1H-imidazol-5-yl)-methyl)-2(3H)-furanone (pilocarpine, PLC), 4,5-dihydro-2-(phenylmethyl)-1H-imidazole (tolazoline, TLZ), 2-methyl-5-nitro-1H-imidazole-1-ethanol (metronidazole, MET) and 1H-imidazole-4-ethanamine (histamine, HIST) was investigated. The stability constants, ..beta../sub n/, of these complexes were determined. It was shown that the electron-donor strength of the ligands was controlled by the heterocyclic nitrogen atom, and that the formation of the Zn(2)-PLC complex was accompanied by the change in the structure of the coordination sphere of the metal. With Cu(2), the PLC and TLZ ligands were shown to enhance the Jahn-Teller deformation.

Interaction between Nbp35 and Cfd1 proteins of cytosolic Fe-S cluster assembly reveals a stable complex formation in Entamoeba histolytica.

Directory of Open Access Journals (Sweden)

Shadab Anwar

Full Text Available Iron-Sulfur (Fe-S proteins are involved in many biological functions such as electron transport, photosynthesis, regulation of gene expression and enzymatic activities. Biosynthesis and transfer of Fe-S clusters depend on Fe-S clusters assembly processes such as ISC, SUF, NIF, and CIA systems. Unlike other eukaryotes which possess ISC and CIA systems, amitochondriate Entamoeba histolytica has retained NIF & CIA systems for Fe-S cluster assembly in the cytosol. In the present study, we have elucidated interaction between two proteins of E. histolytica CIA system, Cytosolic Fe-S cluster deficient 1 (Cfd1 protein and Nucleotide binding protein 35 (Nbp35. In-silico analysis showed that structural regions ranging from amino acid residues (P33-K35, G131-V135 and I147-E151 of Nbp35 and (G5-V6, M34-D39 and G46-A52 of Cfd1 are involved in the formation of protein-protein complex. Furthermore, Molecular dynamic (MD simulations study suggested that hydrophobic forces surpass over hydrophilic forces between Nbp35 and Cfd1 and Van-der-Waal interaction plays crucial role in the formation of stable complex. Both proteins were separately cloned, expressed as recombinant fusion proteins in E. coli and purified to homogeneity by affinity column chromatography. Physical interaction between Nbp35 and Cfd1 proteins was confirmed in vitro by co-purification of recombinant Nbp35 with thrombin digested Cfd1 and in vivo by pull down assay and immunoprecipitation. The insilico, in vitro as well as in vivo results prove a stable interaction between these two proteins, supporting the possibility of its involvement in Fe-S cluster transfer to target apo-proteins through CIA machinery in E. histolytica. Our study indicates that initial synthesis of a Fe-S precursor in mitochondria is not necessary for the formation of Cfd1-Nbp35 complex. Thus, Cfd1 and Nbp35 with the help of cytosolic NifS and NifU proteins can participate in the maturation of non-mitosomal Fe-S proteins

Comparative biogeochemical behaviors of iron-55 and stable iron in the marine environment

International Nuclear Information System (INIS)

Weimer, W.C.; Langford, J.C.; Jenkins, C.E.

1978-01-01

Studies of atmospheric aerosols have demonstrated that much of the 55 Fe associated with the aerosol input to the oceans is present as either an amorphous or hydrous iron oxide or as very small particulate species attached to the surfaces of the large aerosol particles. By comparison, nearly all of the stable iron is bound in the mineral phase of aerosol particles. This difference in the chemical and physical forms of the radioactive and stable iron isotopes results in the 55 Fe being more biologically available than is the stable iron. This difference in availability is responsible for the transfer of a much higher specific activity 55 Fe to certain ocean organisms and man relative to the specific activity of the total aerosol or of sea water. This differential biological uptake of the radioactive element and its stable element counterpart points out that natural levels of stable elements in the marine environment may not effectively dilute radioelements or other stable elements of anthropogenic sources. The effectiveness of dilution by natural sources depends on the chemical and physical forms of the materials in both the source terms and the receiving environments. The large difference in specific activities of 55 Fe in aerosols and sea water relative to ocean organisms reflects the independent behaviors of 55 Fe and stable iron

A note on Hermitian-Einstein metrics on parabolic stable bundles

International Nuclear Information System (INIS)

Li Jiayu; Narasimhan, M.S.

2000-01-01

Let M-bar be a compact complex manifold of complex dimension two with a smooth Kaehler metric and D a smooth divisor on M-bar. If E is a rank 2 holomorphic vector bundle on M-bar with a stable parabolic structure along D, we prove that there exists a Hermitian-Einstein metric on E' = E-vertical bar M-barbackslashD compatible with the parabolic structure, and whose curvature is square integrable. (author)

A neutral lipophilic complex of sup(99m)Tc with a multidentate amine oxime

International Nuclear Information System (INIS)

Troutner, D.E.; Volkert, W.A.; Hoffman, T.J.; Holmes, R.A.

1984-01-01

Propylene amine oxime, 3,3'-(1,3-propanediyldiimino)bis(3-methyl-2-butanone)dioxime, (PnAO) forms a neutral lipophilic complex with sup(99m)Tc in >95% yield at room temperature at pH 5-10. The complex can be prepared with generator produced sup(99m)Tc using 10 -5 M SnC 4 H 4 O 6 as the reducing agent at ligand concentrations as low as 3 x 10 -5 M. It is stable in saline solutions for as long as 24 h. [Sup(99m)Tc]PnAO may be useful as an imaging agent which passively diffuses across the blood brain barrier. (author)

Migraine genetics : from monogenic to complex forms

NARCIS (Netherlands)

Vanmolkot, Kaate Raymond Josepha

2008-01-01

Migraine has a strong genetic component, but the identification of these factors has proven difficult mainly because of the complex interaction of multiple loci and environmental factors. Unraveling its molecular basis and deciphering pathways leading to migraine attacks will help identifying novel

IgG Fab Fragments Forming Bivalent Complexes by a Conformational Mechanism That Is Reversible by Osmolytes*

Science.gov (United States)

Nelson, Alfreda D.; Hoffmann, Michele M.; Parks, Christopher A.; Dasari, Surendra; Schrum, Adam G.; Gil, Diana

2012-01-01

Generated by proteolytic cleavage of immunoglobulin, Fab fragments possess great promise as blocking reagents, able to bind receptors or other targets without inducing cross-linking. However, aggregation of Fab preparations is a common occurrence, which generates intrinsic stimulatory capacity and thwarts signal blockade strategies. Using a panel of biochemical approaches, including size exclusion chromatography, SDS-PAGE, mass spectrometry, and cell stimulation followed by flow cytometry, we have measured the oligomerization and acquisition of stimulatory capacity that occurs in four monoclonal IgG Fabs specific for TCR/CD3. Unexpectedly, we observed that all Fabs spontaneously formed complexes that were precisely bivalent, and these bivalent complexes possessed most of the stimulatory activity of each Fab preparation. Fabs composing bivalent complexes were more susceptible to proteolysis than monovalent Fabs, indicating a difference in conformation between the Fabs involved in these two different states of valency. Because osmolytes represent a class of compounds that stabilize protein folding and conformation, we sought to determine the extent to which the amino acid osmolyte l-proline might impact bivalent Fab complexation. We found that l-proline (i) inhibited the adoption of the conformation associated with bivalent complexation, (ii) preserved Fab monovalency, (iii) reversed the conformation of preformed bivalent Fabs to that of monovalent Fabs, and (iv) separated a significant percentage of preformed bivalent complexes into monovalent species. Thus, Fab fragments can adopt a conformation that is compatible with folding or packing of a bivalent complex in a process that can be inhibited by osmolytes. PMID:23109335

pH-induced photocurrent switching based on a highly stable drop-casting film of imidazole moiety-containing dinuclear Ru(II) Complex

International Nuclear Information System (INIS)

Xue, Long-Xin; Duan, Zhi-Ming; Jia, Jia; Wang, Ke-Zhi; Haga, Masa-aki

2014-01-01

Graphical abstract: > Solvent-casting Ru(II) complex modified electrode. > Positive shifting of half-wave potentials of Ru(III)/Ru(II) by pH decreases. > Greatly enhanced cathodic photocurrents by pH decreases. - Highlights: • Solvent-casting Ru(II) complex modified electrode. • Positive shifting of half-wave potentials of Ru(III)/Ru(II) by pH decreases. • Greatly enhanced cathodic photocurrents by pH decreases. - Abstract: A new dinuclear Ru(II) complex of [(H 2 L 1 )Ru(H 2 L 2 )Ru(H 2 L 1 )](ClO 4 ) 4 {H 2 L 1 = 2,6-bis(2-benzimidazolyl)pyridine; H 2 L 2 = 2,6-bis(4-([2,2′:6′,2″-terpyridin]-4′-yl)phenyl)-1,5- dihydrobenzo[1,2-d:4,5-d’]diimidazole} is synthesized and characterized. The Ru(II) complex modified indium-tin oxide electrode prepared using a drop-casting method, exhibited a couple of stable surface-confined Ru(III)/Ru(II)-based redox waves centered at +0.65 V vs saturated calomel electrode that were almost unchanged after 50 consecutive cyclic voltammetry scanning. The modified electrode showed pH-dependent redox behaviors with the formal potential being decreased by 430 mV due to the occurrance of the proton-coupled redox reactions. The cathodic photocurrent generation of the modified electrode was also found to be highly pH-dependent, switching from an “off” state at pH ∼11.0 to an “on” state at pH = 2.20 with an enhancement factor of 18. The modified electrode was shown to have promising applications as photoelectrochemical pH sensing and switching devices

Fundamentals of the LISA stable flight formation

International Nuclear Information System (INIS)

Dhurandhar, S V; Nayak, K Rajesh; Koshti, S; Vinet, J-Y

2005-01-01

The joint NASA-ESA mission, LISA, relies crucially on the stability of the three-spacecraft constellation. Each of the spacecraft is in heliocentric orbit forming a stable triangle. In this paper we explicitly show with the help of the Clohessy-Wiltshire equations that any configuration of spacecraft lying in the planes making angles of ±60 0 with the ecliptic and given suitable initial velocities within the plane, can be made stable in the sense that the inter-spacecraft distances remain constant to first order in the dimensions of the configuration compared with the distance to the Sun. Such analysis would be useful in order to carry out theoretical studies on the optical links, simulators, etc

Dynamics of water around the complex structures formed between the KH domains of far upstream element binding protein and single-stranded DNA molecules

Energy Technology Data Exchange (ETDEWEB)

Chakraborty, Kaushik; Bandyopadhyay, Sanjoy, E-mail: sanjoy@chem.iitkgp.ernet.in [Molecular Modeling Laboratory, Department of Chemistry, Indian Institute of Technology, Kharagpur 721302 (India)

2015-07-28

Single-stranded DNA (ss-DNA) binding proteins specifically bind to the single-stranded regions of the DNA and protect it from premature annealing, thereby stabilizing the DNA structure. We have carried out atomistic molecular dynamics simulations of the aqueous solutions of two DNA binding K homology (KH) domains (KH3 and KH4) of the far upstream element binding protein complexed with two short ss-DNA segments. Attempts have been made to explore the influence of the formation of such complex structures on the microscopic dynamics and hydrogen bond properties of the interfacial water molecules. It is found that the water molecules involved in bridging the ss-DNA segments and the protein domains form a highly constrained thin layer with extremely retarded mobility. These water molecules play important roles in freezing the conformational oscillations of the ss-DNA oligomers and thereby forming rigid complex structures. Further, it is demonstrated that the effect of complexation on the slow long-time relaxations of hydrogen bonds at the interface is correlated with hindered motions of the surrounding water molecules. Importantly, it is observed that the highly restricted motions of the water molecules bridging the protein and the DNA components in the complexed forms originate from more frequent hydrogen bond reformations.

A Stable-Isotope Mass Spectrometry-Based Metabolic Footprinting Approach to Analyze Exudates from Phytoplankton

Directory of Open Access Journals (Sweden)

Mark R. Viant

2013-10-01

Full Text Available Phytoplankton exudates play an important role in pelagic ecology and biogeochemical cycles of elements. Exuded compounds fuel the microbial food web and often encompass bioactive secondary metabolites like sex pheromones, allelochemicals, antibiotics, or feeding attractants that mediate biological interactions. Despite this importance, little is known about the bioactive compounds present in phytoplankton exudates. We report a stable-isotope metabolic footprinting method to characterise exudates from aquatic autotrophs. Exudates from 13C-enriched alga were concentrated by solid phase extraction and analysed by high-resolution Fourier transform ion cyclotron resonance mass spectrometry. We used the harmful algal bloom forming dinoflagellate Alexandrium tamarense to prove the method. An algorithm was developed to automatically pinpoint just those metabolites with highly 13C-enriched isotope signatures, allowing us to discover algal exudates from the complex seawater background. The stable-isotope pattern (SIP of the detected metabolites then allowed for more accurate assignment to an empirical formula, a critical first step in their identification. This automated workflow provides an effective way to explore the chemical nature of the solutes exuded from phytoplankton cells and will facilitate the discovery of novel dissolved bioactive compounds.

Differential forms orthogonal to holomorphic functions or forms, and their properties

CERN Document Server

Aizenberg, L A

1983-01-01

The authors consider the problem of characterizing the exterior differential forms which are orthogonal to holomorphic functions (or forms) in a domain D\\subset {\\mathbf C}^n with respect to integration over the boundary, and some related questions. They give a detailed account of the derivation of the Bochner-Martinelli-Koppelman integral representation of exterior differential forms, which was obtained in 1967 and has already found many important applications. They study the properties of \\overline \\partial-closed forms of type (p, n - 1), 0\\leq p\\leq n - 1, which turn out to be the duals (with respect to the orthogonality mentioned above) to holomorphic functions (or forms) in several complex variables, and resemble holomorphic functions of one complex variable in their properties.

Electrically active induced energy levels and metastability of B and N vacancy-complexes in 4H-SiC.

Science.gov (United States)

Igumbor, E; Olaniyan, O; Mapasha, R E; Danga, H T; Omotoso, E; Meyer, W E

2018-05-10

Electrically active induced energy levels in semiconductor devices could be beneficial to the discovery of an enhanced p or n-type semiconductor. Nitrogen (N) implanted into 4H-SiC is a high energy process that produced high defect concentrations which could be removed during dopant activation annealing. On the other hand, boron (B) substituted for silicon in SiC causes a reduction in the number of defects. This scenario leads to a decrease in the dielectric properties and induced deep donor and shallow acceptor levels. Complexes formed by the N, such as the nitrogen-vacancy centre, have been reported to play a significant role in the application of quantum bits. In this paper, results of charge states thermodynamic transition level of the N and B vacancy-complexes in 4H-SiC are presented. We explore complexes where substitutional N[Formula: see text]/N[Formula: see text] or B[Formula: see text]/B[Formula: see text] sits near a Si (V[Formula: see text]) or C (V[Formula: see text]) vacancy to form vacancy-complexes (N[Formula: see text]V[Formula: see text], N[Formula: see text]V[Formula: see text], N[Formula: see text]V[Formula: see text], N[Formula: see text]V[Formula: see text], B[Formula: see text]V[Formula: see text], B[Formula: see text]V[Formula: see text], B[Formula: see text]V[Formula: see text] and B[Formula: see text]V[Formula: see text]). The energies of formation of the N related vacancy-complexes showed the N[Formula: see text]V[Formula: see text] to be energetically stable close to the valence band maximum in its double positive charge state. The N[Formula: see text]V[Formula: see text] is more energetically stable in the double negative charge state close to the conduction band minimum. The N[Formula: see text]V[Formula: see text] on the other hand, induced double donor level and the N[Formula: see text]V[Formula: see text] induced a double acceptor level. For B related complexes, the B[Formula: see text]V[Formula: see text] and B[Formula: see text

Mathematics for electric engineers. Complex numbers; Mathematiques pour l`electricien. Nombres complexes

Energy Technology Data Exchange (ETDEWEB)

Rouxel, C. [Conservatoire National des Arts et Metiers (CNAM), 75 - Paris (France)

1999-05-01

Complex numbers are widely used in electrical engineering. This article is divided into 5 parts dealing successively with: the cartesian form of complex numbers (definition, conjugated complex numbers, graphical representation); the trigonometrical form of complex numbers (module and argument, trigonometrical form, exponential notation, multiplication and division of two complex numbers); Moivre and Euler formulae; applications (square root and second degree equation, n. roots, plan rotation and similarity); cissoidal transformation (definition, properties, applications to electricity: complex impedance in permanent sinusoidal regime, transfer function of a linear system in permanent regime, study of an example). (J.S.)

Principal Physicochemical Methods Used to Characterize Dendrimer Molecule Complexes Used as Genetic Therapy Agents, Nanovaccines or Drug Carriers.

Science.gov (United States)

Alberto, Rodríguez Fonseca Rolando; Joao, Rodrigues; de Los Angeles, Muñoz-Fernández María; Alberto, Martínez Muñoz; Manuel Jonathan, Fragoso Vázquez; José, Correa Basurto

2017-08-30

Nanomedicine is the application of nanotechnology to medicine. This field is related to the study of nanodevices and nanomaterials applied to various medical uses, such as in improving the pharmacological properties of different molecules. Dendrimers are synthetic nanoparticles whose physicochemical properties vary according to their chemical structure. These molecules have been extensively investigated as drug nanocarriers to improve drug solubility and as sustained-release systems. New therapies such as gene therapy and the development of nanovaccines can be improved by the use of dendrimers. The biophysical and physicochemical characterization of nucleic acid/peptide-dendrimer complexes is crucial to identify their functional properties prior to biological evaluation. In that sense, it is necessary to first identify whether the peptide-dendrimer or nucleic aciddendrimer complexes can be formed and whether the complex can dissociate under the appropriate conditions at the target cells. In addition, biophysical and physicochemical characterization is required to determine how long the complexes remain stable, what proportion of peptide or nucleic acid is required to form the complex or saturate the dendrimer, and the size of the complex formed. In this review, we present the latest information on characterization systems for dendrimer-nucleic acid, dendrimer-peptide and dendrimer-drug complexes with several biotechnological and pharmacological applications. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Direct transition from a stable equilibrium to quasiperiodicity in non-smooth systems

DEFF Research Database (Denmark)

Zhusubaliyev, Z.T.; Mosekilde, Erik

2008-01-01

The purpose of this Letter is to show how a border-collision bifurcation in a piecewise-smooth dynamical system can produce a direct transition from a stable equilibrium point to a two-dimensional invariant torus. Considering a system of nonautonomous differential equations describing the behavior...... of a power electronic DC/DC converter, we first determine the chart of dynamical modes and show that there is a region of parameter space in which the system has a single stable equilibrium point. Under variation of the parameters, this equilibrium may collide with a discontinuity boundary between two smooth...... regions in phase space. When this happens, one can observe a number of different bifurcation scenarios. One scenario is the continuous transformation of the stable equilibrium into a stable period-1 cycle. Another is the transformation of the stable equilibrium into an unstable period-1 cycle with complex...

Synthesis of Cr(III-Morin Complex: Characterization and Antioxidant Study

Directory of Open Access Journals (Sweden)

Qadeer K. Panhwar

2014-01-01

Full Text Available The complex formation between Cr(III and morin was carried out in methanol and confirmed by analytical characterization using UV-Vis, IR, 1H NMR, and TG-DTA. UV-Vis shows significant bathochromic shift in benzoyl upon coordination as well as IR well illustrates the peak shift of C=O group and formation of a O–Cr(III bond. Likewise, 1H NMR studies clarify that Cr(III metal ion replaces the 5OH proton hence; 5-hydroxy-4-keto site is employed by morin in chelation to form six-membered stable ring system out of three available chelating sites. In addition, TG-DTA denotes the presence of coordinated and crystalline water molecules. The melting point of the complex was found to be 389°C by DSC. In addition, Cr(III-morin complex was found to be a more potent antioxidant than morin as evaluated by DPPH• and FRAP methods.

Assessment of Stable Isotope Distribution in Complex Systems

Science.gov (United States)

He, Y.; Cao, X.; Wang, J.; Bao, H.

2017-12-01

Biomolecules in living organisms have the potential to approach chemical steady state and even apparent isotope equilibrium because enzymatic reactions are intrinsically reversible. If an apparent local equilibrium can be identified, enzymatic reversibility and its controlling factors may be quantified, which helps to understand complex biochemical processes. Earlier research on isotope fractionation tends to focus on specific process and compare mostly two different chemical species. Using linear regression, "Thermodynamic order", which refers to correlated δ13C and 13β values, has been proposed to be present among many biomolecules by Galimov et al. However, the concept "thermodynamic order" they proposed and the approach they used has been questioned. Here, we propose that the deviation of a complex system from its equilibrium state can be rigorously described as a graph problem as is applied in discrete mathematics. The deviation of isotope distribution from equilibrium state and apparent local isotope equilibrium among a subset of biomolecules can be assessed using an apparent fractionation difference matrix (|Δα|). Applying the |Δα| matrix analysis to earlier published data of amino acids, we show the existence of apparent local equilibrium among different amino acids in potato and a kind of green alga. The existence of apparent local equilibrium is in turn consistent with the notion that enzymatic reactions can be reversible even in living systems. The result also implies that previous emphasis on external carbon source intake may be misplaced when studying isotope distribution in physiology. In addition to the identification of local equilibrium among biomolecules, the difference matrix approach has the potential to explore chemical or isotope equilibrium state in extraterrestrial bodies, to distinguish living from non-living systems, and to classify living species. This approach will benefit from large numbers of systematic data and advanced pattern

Unraveling chaotic attractors by complex networks and measurements of stock market complexity

International Nuclear Information System (INIS)

Cao, Hongduo; Li, Ying

2014-01-01

We present a novel method for measuring the complexity of a time series by unraveling a chaotic attractor modeled on complex networks. The complexity index R, which can potentially be exploited for prediction, has a similar meaning to the Kolmogorov complexity (calculated from the Lempel–Ziv complexity), and is an appropriate measure of a series' complexity. The proposed method is used to research the complexity of the world's major capital markets. None of these markets are completely random, and they have different degrees of complexity, both over the entire length of their time series and at a level of detail. However, developing markets differ significantly from mature markets. Specifically, the complexity of mature stock markets is stronger and more stable over time, whereas developing markets exhibit relatively low and unstable complexity over certain time periods, implying a stronger long-term price memory process

Unraveling chaotic attractors by complex networks and measurements of stock market complexity.

Science.gov (United States)

Cao, Hongduo; Li, Ying

2014-03-01

We present a novel method for measuring the complexity of a time series by unraveling a chaotic attractor modeled on complex networks. The complexity index R, which can potentially be exploited for prediction, has a similar meaning to the Kolmogorov complexity (calculated from the Lempel-Ziv complexity), and is an appropriate measure of a series' complexity. The proposed method is used to research the complexity of the world's major capital markets. None of these markets are completely random, and they have different degrees of complexity, both over the entire length of their time series and at a level of detail. However, developing markets differ significantly from mature markets. Specifically, the complexity of mature stock markets is stronger and more stable over time, whereas developing markets exhibit relatively low and unstable complexity over certain time periods, implying a stronger long-term price memory process.

Synthesis and X-ray Crystal Structure of a Stable cis-1,2-bis(diphenylphosphinoethene Monodentate Thiolate Platinum Complex and TGA Studies of its Precursors

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Vaz Rodrigo H.

2002-01-01

Full Text Available The stable Pt(II complex [Pt(SPh2(dppen (4, (dppen, Ph2PCH=CHPPh2 was obtained from [PtCl(SPh2(SnPh3cod] (1 (cod = 1,5-cyclooctadiene by reductive elimination reaction of SnClPh3 and substitution of the cod ligand by the diphosphine, albeit in low yields. Yields of 80% were obtained when [Pt(SPh2cod] (3 was used as the starting material instead. The viability of these reactions was suggested by a TG study, performed on the starting materials. Complex 4 was characterized by multinuclear NMR (195Pt, 31P, ¹H and 13C and IR spectroscopies and elemental analysis. The molecular structure, solved by an X-ray diffraction study, exhibted a slightly distorted square-planar geometry and short C=C and Pt-P bond distances which were interpreted in terms of a p interaction between the double bond and the metal-ligand bond, as observed for other diphosphine compounds described previously.

Decomposition of overlapping protein complexes: A graph theoretical method for analyzing static and dynamic protein associations

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Guimarães Katia S

2006-04-01

Full Text Available Abstract Background Most cellular processes are carried out by multi-protein complexes, groups of proteins that bind together to perform a specific task. Some proteins form stable complexes, while other proteins form transient associations and are part of several complexes at different stages of a cellular process. A better understanding of this higher-order organization of proteins into overlapping complexes is an important step towards unveiling functional and evolutionary mechanisms behind biological networks. Results We propose a new method for identifying and representing overlapping protein complexes (or larger units called functional groups within a protein interaction network. We develop a graph-theoretical framework that enables automatic construction of such representation. We illustrate the effectiveness of our method by applying it to TNFα/NF-κB and pheromone signaling pathways. Conclusion The proposed representation helps in understanding the transitions between functional groups and allows for tracking a protein's path through a cascade of functional groups. Therefore, depending on the nature of the network, our representation is capable of elucidating temporal relations between functional groups. Our results show that the proposed method opens a new avenue for the analysis of protein interaction networks.

Characterization of Protein and Peptide Binding to Nanogels Formed by Differently Charged Chitosan Derivatives

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Anastasia Zubareva

2013-07-01

Full Text Available Chitosan (Chi is a natural biodegradable cationic polymer with remarkable potency as a vehicle for drug or vaccine delivery. Chi possesses multiple groups, which can be used both for Chi derivatization and for particle formation. The aim of this work was to produce stable nanosized range Chi gels (nanogels, NGs with different charge and to study the driving forces of complex formation between Chi NGs and proteins or peptides. Positively charged NGs of 150 nm in diameter were prepared from hexanoyl chitosan (HC by the ionotropic gelation method while negatively charged NGs of 190 nm were obtained from succinoyl Chi (SC by a Ca2+ coacervation approach. NGs were loaded with a panel of proteins or peptides with different weights and charges. We show that NGs preferentially formed complexes with oppositely charged molecules, especially peptides, as was demonstrated by gel-electrophoresis, confocal microscopy and HPLC. Complex formation was accompanied by a change in zeta-potential and decrease in size. We concluded that complex formation between Chi NGs and peptide/proteins is mediated mostly by electrostatic interactions.

Human orexin/hypocretin receptors form constitutive homo- and heteromeric complexes with each other and with human CB{sub 1} cannabinoid receptors

Energy Technology Data Exchange (ETDEWEB)

Jäntti, Maria H., E-mail: maria.jantti@helsinki.fi [Department of Veterinary Biosciences, POB 66, FIN-00014 University of Helsinki (Finland); Mandrika, Ilona, E-mail: ilona@biomed.lu.lv [Latvian Biomedical Research and Study Centre, Ratsupites Str. 1, Riga LV 1067 (Latvia); Kukkonen, Jyrki P., E-mail: jyrki.kukkonen@helsinki.fi [Department of Veterinary Biosciences, POB 66, FIN-00014 University of Helsinki (Finland)

2014-03-07

Highlights: • OX{sub 1} and OX{sub 2} orexin and CB{sub 1} cannabinoid receptor dimerization was investigated. • Bioluminescence resonance energy transfer method was used. • All receptors readily formed constitutive homo- and heteromeric complexes. - Abstract: Human OX{sub 1} orexin receptors have been shown to homodimerize and they have also been suggested to heterodimerize with CB{sub 1} cannabinoid receptors. The latter has been suggested to be important for orexin receptor responses and trafficking. In this study, we wanted to assess the ability of the other combinations of receptors to also form similar complexes. Vectors for expression of human OX{sub 1}, OX{sub 2} and CB{sub 1} receptors, C-terminally fused with either Renilla luciferase or GFP{sup 2} green fluorescent protein variant, were generated. The constructs were transiently expressed in Chinese hamster ovary cells, and constitutive dimerization between the receptors was assessed by bioluminescence energy transfer (BRET). Orexin receptor subtypes readily formed homo- and hetero(di)mers, as suggested by significant BRET signals. CB{sub 1} receptors formed homodimers, and they also heterodimerized with both orexin receptors. Interestingly, BRET efficiency was higher for homodimers than for almost all heterodimers. This is likely to be due to the geometry of the interaction; the putatively symmetric dimers may place the C-termini in a more suitable orientation in homomers. Fusion of luciferase to an orexin receptor and GFP{sup 2} to CB{sub 1} produced more effective BRET than the opposite fusions, also suggesting differences in geometry. Similar was seen for the OX{sub 1}–OX{sub 2} interaction. In conclusion, orexin receptors have a significant propensity to make homo- and heterodi-/oligomeric complexes. However, it is unclear whether this affects their signaling. As orexin receptors efficiently signal via endocannabinoid production to CB{sub 1} receptors, dimerization could be an effective way

Thermochemistry of minerals stable near the earth's surface

International Nuclear Information System (INIS)

1990-01-01

The present proposal continues the evolution, of changing emphasis from silicate melts to glass and toward crystalline minerals stable in the shallow crustal environment, particularly amphiholes, micas, and related hydrous phases adding zeolites and carbonates to our areas of interest. This is made possible both by recent advances in our high-temperature calorimetric techniques and by an interest in extending our ideas about the systematics of ionic substitutions to more complex structures. The proposal presents the following: (a) a listing of papers, theses, and abstracts in the past 3 years supported by the present grant, (b) a summary of work on glasses containing highly charged cations and on some related crystalline phases, with proposed new directions, (c) a discussion of advances in calorimetric methods and what new possibilities they open, (d) completed and planned work on amphiboles, micas, and clays, (e) completed and proposed work on amorpous low temperature materials, (f) proposed work on zeolites, and (g) proposed work on carbonates and (h) a discussion of the energy relevance of the above projects. This is followed by the required forms, budget pages, and CV. 34 refs., 5 figs., 1 tab

Zirconium (IV) complexes with some polymethylenediimines | Na ...

African Journals Online (AJOL)

The syntheses of zirconium (IV) complexes have been carried out by the reaction of oxozirconium (IV) chloride with the appropriate diimines (Schiff bases). The complexes were isolated as yellow solids which are stable to heat. The complexes were found to be insoluble in most solvents. The infrared spectra, elemental ...

Purification, crystallization and preliminary X-ray crystallographic analysis of the ATPase domain of human TAP in nucleotide-free and ADP-, vanadate- and azide-complexed forms

International Nuclear Information System (INIS)

Meena, Sita R.; Gangwar, Shanti P.; Saxena, Ajay K.

2012-01-01

The ATPase domain of human TAP in nucleotide free, ADP, vanadate and azide complexed forms were purified and crystallized. The X-ray diffraction data sets were collected for all crystals in the resolution range of 2.8–3.0 Å. The human transporter associated with antigen processing (TAP) protein belongs to the ATP-binding cassette (ABC) transporter superfamily and is formed by the heterodimerization of TAP1 and TAP2 subunits. TAP selectively pumps cytosolic peptides into the lumen of the endoplasmic reticulum in an ATP-dependent manner. The catalytic cycle of the ATPase domain of TAP is not understood at the molecular level. The structures of catalytic intermediates of the ATPase domain of TAP will contribute to the understanding of the chemical mechanism of ATP hydrolysis. In order to understand this mechanism, the ATPase domain of human TAP1 (NBD1) was expressed and purified, crystallized in nucleotide-free and transition-state complex forms and X-ray crystallographic studies were performed. The NBD1 protein was crystallized (i) in the nucleotide-free apo form; (ii) in complex with ADP–Mg 2+ , mimicking the product-bound state; (iii) in complex with vanadate–ADP–Mg 2+ , mimicking the ATP-bound state; and (iv) in complex with azide–ADP–Mg 2+ , also mimicking the ATP-bound state. X-ray diffraction data sets were collected for apo and complexed NBD1 using an in-house X-ray diffraction facility at a wavelength of 1.5418 Å. The apo and complexed NBD1 crystals belonged to the primitive hexagonal space group P6 2 , with one monomer in the asymmetric unit. Here, the crystallization, data collection and preliminary crystallographic analysis of apo and complexed NBD1 are reported

AB INITIO INVESTIGATION OF 12-CROWN-4 AND BENZO-12-CROWN-4 COMPLEXES WITH Li+, Na+, K+, Zn2+, Cd2+, AND Hg2+

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Yahmin Yahmin

2010-06-01

Full Text Available The structure and binding energies of 12-crown-4 and benzo-12-crown-4 complexes with Li+, Na+, K+, Zn2+, Cd2+, and Hg2+were investigated with ab initio calculations using Hartree-Fock approximation and second-order perturbation theory. The basis set used in this study is lanl2mb. The structure optimization of cation-crown ether complexes was evaluated at HF/lanl2mb level of theory and interaction energy of the corresponding complexes was calculated at MP2/lanl2mb level of theory (MP2/lanl2mb//HF/lanl2mb. Interactions of the crown ethers and the cations were discussed in term of the structure parameter of crown ether. The binding energies of the complexes show that all complex formed from transition metal cations is more stable than the complexes formed from alkali metal cations.   Keywords: 12-crown-4, benzo-12-crown-4, alkali metals, transition metals

Earth's first stable continents did not form by subduction.

Science.gov (United States)

Johnson, Tim E; Brown, Michael; Gardiner, Nicholas J; Kirkland, Christopher L; Smithies, R Hugh

2017-03-09

The geodynamic environment in which Earth's first continents formed and were stabilized remains controversial. Most exposed continental crust that can be dated back to the Archaean eon (4 billion to 2.5 billion years ago) comprises tonalite-trondhjemite-granodiorite rocks (TTGs) that were formed through partial melting of hydrated low-magnesium basaltic rocks; notably, these TTGs have 'arc-like' signatures of trace elements and thus resemble the continental crust produced in modern subduction settings. In the East Pilbara Terrane, Western Australia, low-magnesium basalts of the Coucal Formation at the base of the Pilbara Supergroup have trace-element compositions that are consistent with these being source rocks for TTGs. These basalts may be the remnants of a thick (more than 35 kilometres thick), ancient (more than 3.5 billion years old) basaltic crust that is predicted to have existed if Archaean mantle temperatures were much hotter than today's. Here, using phase equilibria modelling of the Coucal basalts, we confirm their suitability as TTG 'parents', and suggest that TTGs were produced by around 20 per cent to 30 per cent melting of the Coucal basalts along high geothermal gradients (of more than 700 degrees Celsius per gigapascal). We also analyse the trace-element composition of the Coucal basalts, and propose that these rocks were themselves derived from an earlier generation of high-magnesium basaltic rocks, suggesting that the arc-like signature in Archaean TTGs was inherited from an ancestral source lineage. This protracted, multistage process for the production and stabilization of the first continents-coupled with the high geothermal gradients-is incompatible with modern-style plate tectonics, and favours instead the formation of TTGs near the base of thick, plateau-like basaltic crust. Thus subduction was not required to produce TTGs in the early Archaean eon.

Stable isotopes

International Nuclear Information System (INIS)

Evans, D.K.

1986-01-01

Seventy-five percent of the world's stable isotope supply comes from one producer, Oak Ridge Nuclear Laboratory (ORNL) in the US. Canadian concern is that foreign needs will be met only after domestic needs, thus creating a shortage of stable isotopes in Canada. This article describes the present situation in Canada (availability and cost) of stable isotopes, the isotope enrichment techniques, and related research programs at Chalk River Nuclear Laboratories (CRNL)

Spectral and thermal behaviours of rare earth element complexes with 3,5-dimethoxybenzoic acid

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JANUSZ CHRUŚCIEL

2003-10-01

Full Text Available The conditions for the formation of rare earth element 3,5-dimethytoxybenzoates were studied and their quantitative composition and solubilities in water at 293 K were determined. The complexes are anhydrous or hydrated salts and their solubilities are of the orders of 10-5 – 10-4 mol dm-3. Their FTIR, FIR and X-ray spectra were recorded. The compounds were also characterized by thermogravimetric studies in air and nitrogen atmospheres and by magnetic measurements. All complexes are crystalline compounds. The carboxylate group in these complexes is a bidentate, chelating ligand. On heating in air to 1173 K, the 3,5-dimethoxybenzoates of rare earth elements decompose in various ways. The hydrated complexes first dehydrate to form anhydrous salts which then decompose in air to the oxides of the respective metals while in nitrogen to mixtures of carbon and oxides of the respective metals. The complexes are more stable in air than in nitrogen.

Sensitive and selective spectrophotometric assay of piroxicam in pure form, capsule and human blood serum samples via ion-pair complex formation

Science.gov (United States)

Alizadeh, Nina; Keyhanian, Fereshteh

2014-09-01

A simple, accurate and highly sensitive spectrophotometric method has been developed for the rapid determination of piroxicam (PX) in pure and pharmaceutical formulations. The proposed method involves formation of stable yellow colored ion-pair complexes of the amino derivative (basic nitrogen) of PX with three sulphonphthalein acid dyes namely; bromocresol green (BCG), bromothymol blue (BTB), bromophenol blue (BPB) in acidic medium. The colored species exhibited absorption maxima at 438, 429 and 432 nm with molar absorptivity values of 9.400 × 103, 1.218 × 103 and 1.02 × 104 L mol-1 cm-1 for PX-BCG, PX-BTB and PX-BPB complexes, respectively. The effect of optimum conditions via acidity, reagent concentration, time and solvent were studied. The reactions were extremely rapid at room temperature and the absorbance values remained constant for 48 h. Beer’s law was obeyed with a good correlation coefficient in the concentration ranges 1-100 μg mL-1 for BCG, BTB complexes and 1-95 μg mL-1 for BPB complex. The composition ratio of the ion-pair complexes were found to be 1:1 in all cases as established by Job’s method. No interference was observed from common additives and excipients which may be present in the pharmaceutical preparations. The proposed method was successfully applied for the determination of PX in capsule and human blood serum samples with good accuracy and precision.

Crystalline structure and propylene oxidation in complex bismuth-molybdenum oxide catalysts

International Nuclear Information System (INIS)

Manaila, R.; Ionescu, N.I.; Caldararu, M.

1980-01-01

Complex Bi-Mo oxide catalysts supported on amorphous SiO 2 were prepared by coprecipitation and tested in the reaction of selective oxidation of propylene to acrolein. They consist of a mixture of molybdate phases and excess MoO 3 . The Fe 2 (MoO 4 ) 3 phase was found to have a high concentration of lattice defects, induced by a Mo excess. These defects could be related to the catalytic conversion and to the selectivity to total oxidation by varying the calcination temperature. Calcination above 500 0 C induced also the transition of the metastable modification β-NiMoO 4 to the stable form α, accompanied by a loss of conversion. A complex Bi molybdate with scheelitic structure was found to have a high selectivity to acrolein. (author)

A Compact Unconditionally Stable Method for Time-Domain Maxwell's Equations

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Zhuo Su

2013-01-01

Full Text Available Higher order unconditionally stable methods are effective ways for simulating field behaviors of electromagnetic problems since they are free of Courant-Friedrich-Levy conditions. The development of accurate schemes with less computational expenditure is desirable. A compact fourth-order split-step unconditionally-stable finite-difference time-domain method (C4OSS-FDTD is proposed in this paper. This method is based on a four-step splitting form in time which is constructed by symmetric operator and uniform splitting. The introduction of spatial compact operator can further improve its performance. Analyses of stability and numerical dispersion are carried out. Compared with noncompact counterpart, the proposed method has reduced computational expenditure while keeping the same level of accuracy. Comparisons with other compact unconditionally-stable methods are provided. Numerical dispersion and anisotropy errors are shown to be lower than those of previous compact unconditionally-stable methods.

Electrostatic interactions between polyglutamic acid and polylysine yields stable polyion complex micelles for deoxypodophyllotoxin delivery

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Wang Y

2017-10-01

Full Text Available Yutong Wang,1–3,* Liping Huang,1,2,* Yan Shen,1,2,* Lidan Tang,1,2,4 Runing Sun,1,5 Di Shi,6 Thomas J Webster,6 Jiasheng Tu,1,2 Chunmeng Sun1,2 1Center for Research Development and Evaluation of Pharmaceutical Excipients and Generic Drugs, China Pharmaceutical University, 2State Key Laboratory of Natural Medicines, Department of Pharmaceutics, School of Pharmacy, China Pharmaceutical University, 3Department of Pharmacy, Nanjing University of Chinese Medicine, Nanjing, 4Changzhou Second People’s Hospital, Changzhou, 5School of Engineering, China Pharmaceutical University, Nanjing, People’s Republic of China; 6Department of Chemical Engineering, Northeastern University, Boston, MA, USA *These authors contributed equally to this work Abstract: To achieve enhanced physical stability of poly(ethylene glycol-poly(D,L-lactide polymeric micelles (PEG-PDLLA PMs, a mixture of methoxy PEG-PDLLA-polyglutamate (mPEG-PDLLA-PLG and mPEG-PDLLA-poly(L-lysine (mPEG-PDLLA-PLL copolymers was applied to self-assembled stable micelles with polyion-stabilized cores. Prior to micelle preparation, the synthetic copolymers were characterized by 1H-nuclear magnetic resonance (NMR and infrared spectroscopy (IR, and their molecular weights were calculated by 1H-NMR and gel permeation chromatography (GPC. Dialysis was used to prepare PMs with deoxypodophyllotoxin (DPT. Transmission electron microscopy (TEM images showed that DPT polyion complex micelles (DPT-PCMs were spherical, with uniform distribution and particle sizes of 36.3±0.8 nm. In addition, compared with nonpeptide-modified DPT-PMs, the stability of DPT-PCMs was significantly improved under various temperatures. In the meantime, the pH sensitivity induced by charged peptides allowed them to have a stronger antitumor effect and a pH-triggered release profile. As a result, the dynamic characteristic of DPT-PCM was retained, and high biocompatibility of DPT-PCM was observed in an in vivo study. These results

The role of microorganisms in the mobility of radionuclides in soil II. Evaluation of siderophone-cation complex forming capacity

International Nuclear Information System (INIS)

Konyi, J.; Koska, P.; Berzsenyi, G.; Gazso, L.G.; Appanna, V.D.

1997-01-01

Siderophores are cation binding agents produced by microorganisms. They are specific for Fe(III) but may bind other cations, too. Gram positive bacteria, Gram negative bacteria, filamentous bacteria and fungi isolated from soil samples were examined for siderophore production using chrome-asurol agar plates. We found that 44.5% of the isolates are able to produce siderophores. Spectral analysis of the produced exudates shoved cobalt and zinc binding capacity. Adding of a strong complexing agent (EDDHA) does not influence the stability of the formed metal-complex. (authors)

Selenophene transition metal complexes

Energy Technology Data Exchange (ETDEWEB)

White, Carter James [Iowa State Univ., Ames, IA (United States)

1994-07-27

This research shows that selenophene transition metal complexes have a chemistry that is similar to their thiophene analogs. Selenophene coordination has been demonstrated and confirmed by molecular structure in both the η⁵- and the η¹(Se)-coordination modes. The reaction chemistry of selenophene complexes closely resembles that of the analogous thiophene complexes. One major difference, however, is that selenophene is a better donor ligand than thiophene making the selenophene complexes more stable than the corresponding thiophene complexes. The ⁷⁷Se NMR chemical shift values for selenophene complexes fall within distinct regions primarily depending on the coordination mode of the selenophene ligand. In the final paper, the C-H bond activation of η¹(S)-bound thiophenes, η¹(S)-benzothiophene and η¹(Se)-bound selenophenes has been demonstrated. The deprotonation and rearrangement of the η¹(E)-bound ligand to the carbon bound L-yl complex readily occurs in the presence of base. Reprotonation with a strong acid gives a carbene complex that is unreactive towards nucleophilic attack at the carbene carbon and is stable towards exposure to air. The molecular structure of [Cp(NO)(PPh₃)Re(2-benzothioenylcarbene)]O₃SCF₃ was determined and contains a Re-C bond with substantial double bond character. Methyl substitution for the thienylcarbene or selenylcarbene gives a carbene that rearranges thermally to give back the η¹(E)-bound complex. Based on these model reactions, a new mechanism for the H/D exchange of thiophene over the hydrodesulfurization catalyst has been proposed.

Uncertainty principle and the stable interpretation of spectrometric experiment results

International Nuclear Information System (INIS)

Zhukovskij, E.L.

1984-01-01

Two stable forms for recording least-swuare method used for evaluation of parameters durmng automated processing and interpretation of various type spectra were derived on the basis of the Kramer-Rao inequality. Spectra described by linear equations are considered for which parameter evaluations are recorded in a final form. It is shown that the suggested form of the interpreting functional is maintained for the spectra of different nature (NMR-, IR-, UV-, RS- and mass-spectra), their parameters depending nonlinearly on the wave number

Engineering stable topography in dense bio-mimetic 3D collagen scaffolds

Directory of Open Access Journals (Sweden)

T Alekseeva

2012-01-01

Full Text Available Topographic features are well known to influence cell behaviour and can provide a powerful tool for engineering complex, functional tissues. This study aimed to investigate the mechanisms of formation of a stable micro-topography on plastic compressed (PC collagen gels. The uni-directional fluid flow that accompanies PC of collagen gels creates a fluid leaving surface (FLS and a non-fluid leaving surface (non-FLS. Here we tested the hypothesis that the resulting anisotropy in collagen density and stiffness between FLS and non-FLS would influence the fidelity and stability of micro-grooves patterned on these surfaces. A pattern template of parallel-aligned glass fibres was introduced to the FLS or non-FLS either at the start of the compression or halfway through, when a dense FLS had already formed. Results showed that both early and late patterning of the FLS generated grooves that had depth (25 ±7 µm and 19 ±8 µm, respectively and width (55 ±11 µm and 50 ±12 µm, respectively which matched the glass fibre diameter (50 µm. In contrast, early and late patterning of the non-FLS gave much wider (151 ±50 µm and 89 ±14 µm, respectively and shallower (10 ±2.7 µm and 13 ±3.5 µm, respectively grooves than expected. The depth to width ratio of the grooves generated on the FLS remained unaltered under static culture conditions over 2 weeks, indicating that grooves were stable under long term active cell-mediated matrix remodelling. These results indicate that the FLS, characterised by a higher matrix collagen density and stiffness than the non-FLS, provides the most favourable mechanical surface for precise engineering of a stable micro-topography in 3D collagen hydrogel scaffolds.

Stable Isotope Data

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Tissue samples (skin, bone, blood, muscle) are analyzed for stable carbon, stable nitrogen, and stable sulfur analysis. Many samples are used in their entirety for...

stableGP

Data.gov (United States)

National Aeronautics and Space Administration — The code in the stableGP package implements Gaussian process calculations using efficient and numerically stable algorithms. Description of the algorithms is in the...

A primary microcephaly protein complex forms a ring around parental centrioles.

Science.gov (United States)

Sir, Joo-Hee; Barr, Alexis R; Nicholas, Adeline K; Carvalho, Ofelia P; Khurshid, Maryam; Sossick, Alex; Reichelt, Stefanie; D'Santos, Clive; Woods, C Geoffrey; Gergely, Fanni

2011-10-09

Autosomal recessive primary microcephaly (MCPH) is characterized by a substantial reduction in prenatal human brain growth without alteration of the cerebral architecture and is caused by biallelic mutations in genes coding for a subset of centrosomal proteins. Although at least three of these proteins have been implicated in centrosome duplication, the nature of the centrosome dysfunction that underlies the neurodevelopmental defect in MCPH is unclear. Here we report a homozygous MCPH-causing mutation in human CEP63. CEP63 forms a complex with another MCPH protein, CEP152, a conserved centrosome duplication factor. Together, these two proteins are essential for maintaining normal centrosome numbers in cells. Using super-resolution microscopy, we found that CEP63 and CEP152 co-localize in a discrete ring around the proximal end of the parental centriole, a pattern specifically disrupted in CEP63-deficient cells derived from patients with MCPH. This work suggests that the CEP152-CEP63 ring-like structure ensures normal neurodevelopment and that its impairment particularly affects human cerebral cortex growth.

Dynamics and control of twisting bi-stable structures

Science.gov (United States)

Arrieta, Andres F.; van Gemmeren, Valentin; Anderson, Aaron J.; Weaver, Paul M.

2018-02-01

Compliance-based morphing structures have the potential to offer large shape adaptation, high stiffness and low weight, while reducing complexity, friction, and scalability problems of mechanism based systems. A promising class of structure that enables these characteristics are multi-stable structures given their ability to exhibit large deflections and rotations without the expensive need for continuous actuation, with the latter only required intermittently. Furthermore, multi-stable structures exhibit inherently fast response due to the snap-through instability governing changes between stable states, enabling rapid configuration switching between the discrete number of programmed shapes of the structure. In this paper, the design and utilisation of the inherent nonlinear dynamics of bi-stable twisting I-beam structures for actuation with low strain piezoelectric materials is presented. The I-beam structure consists of three compliant components assembled into a monolithic single element, free of moving parts, and showing large deflections between two stable states. Finite element analysis is utilised to uncover the distribution of strain across the width of the flange, guiding the choice of positioning for piezoelectric actuators. In addition, the actuation authority is maximised by calculating the generalised coupling coefficient for different positions of the piezoelectric actuators. The results obtained are employed to tailor and test I-beam designs exhibiting desired large deflection between stable states, while still enabling the activation of snap-through with the low strain piezoelectric actuators. To this end, the dynamic response of the I-beams to piezoelectric excitation is investigated, revealing that resonant excitations are insufficient to dynamically trigger snap-through. A novel bang-bang control strategy, which exploits the nonlinear dynamics of the structure successfully triggers both single and constant snap-through between the stable states

NMR studies of differences in the conformations and dynamics of ligand complexes formed with mutant dihydrofolate reductases

International Nuclear Information System (INIS)

Birdsall, B.; Andrews, J.; Ostler, G.; Tendler, S.J.B.; Feeney, J.; Roberts, G.C.K.; Davies, R.W.; Cheung, H.T.A.

1989-01-01

Two mutants of Lactobacillus casei dihydrofolate reductase, Trp 21 → Leu and Asp 26 → Glu, have been prepared by using site-directed mutagenesis methods, and their ligand binding and structural properties have been compared with those of the wild-type enzyme. 1 H, 13 C, and 31 P NMR studies have been carried out to characterize the structural changes in the complexes of the mutant and wild-type enzymes. Replacement of the conserved Trp 21 by a Leu residue causes a decrease in activity of the enzyme and reduces the NADPH binding constant by a factor of 400. The binding of substrates and substrate analogues is only slightly affected. 1 H NMR studies of the Trp 21 → Leu enzyme complexes have confirmed the original resonance assignments for Trp 21. In complexes formed with methotrexate and the mutant enzyme, the results indicate some small changes in conformation occurring as much as 14 angstrom away from the site of substitution. For the enzyme-NADPH complexes, the chemical shifts of nuclei in the bound coenzyme indicate that the nicotinamide ring binds differently in complexes with the mutant and the wild-type enzyme. There are complexes where the wild-type enzyme has been shown to exist in solution as a mixture of conformations, and studies on the corresponding complexes with the Trp 21 → Leu mutant indicate that the delicately poised equilibria can be perturbed. Some conformational adjustments are required to allow the carboxylate of Glu 26 to bind effectively to the N1 proton of inhibitors such as methotrexate and trimethoprim

Stable Isotope Evidence for a Complex Fluid Evolution of the Northwestern British Columbia Coast Ranges Related to Terrane Accretion

Science.gov (United States)

Moertle, J.; Holk, G. J.

2015-12-01

Stable isotope geochemistry reveals a complex fluid evolution for the Western Metamorphic Belt (WMB), Coast Ranges Batholith (CRB), Central Gneiss Complex (CGC) and Coast Ranges Megalineament (CRM). These fluids are a product of a complex tectonic history related to terrane accretion that includes oblique convergence, metamorphism, magmatism, and orogenic collapse. From W-to-E, these fluid systems are as follows. High-pressure greenschist-to-amphibolite facies metasedimentary rocks of the WMB record variable mineral δD (-61 to -104‰) and δ18O (e.g., quartz +9.6 to +13.4‰) values with multiple minerals in apparent isotopic equilibrium (T ~ 450-550°C) suggest a low W/R system dominated by metamorphic fluids. Variable and non-equilibrium δD (-53 to -143‰) and δ18O (e.g., biotite +2.3 to +5.3‰) values from diorites of the Quottoon pluton affected by the ductile CRM suggest a complex evolution that involved both metamorphic and meteoric-hydrothermal fluids in this dextral shear zone; these results differ from those 300 km along strike to the north that documented only metamorphic fluids in the CRM (Goldfarb et al., 1988). Our data and those of Magaritz and Taylor (1976) from granulite facies metasediments of the CGC and plutons of the western CRB reveal homogeneous δD values (-62 to -78‰) and a restricted range of δ18O values (e.g., quartz +8.5 to +11.5‰) with all minerals in equilibrium at T > 570°C indicate a system dominated by magmatic fluids. Calculated whole-rock δ18O values (~ +7‰) for the Quottoon pluton and CRB intrusive rocks suggest a mantle origin for these magmas. Reinterpretation of very low δD (< -150‰) and quartz-feldspar δ18O pairs that display extreme disequilibrium (feldspar δ18O values as low as -5‰) from the Ponder pluton, eastern CRB, and Hazelton Group point reveals that the major meteoric-hydrothermal system that affected these rocks was related to Eocene detachment faulting along the Shames Lake fault system, a

Preparation and isolation of dithiolene thiophosphoryl molecules as stable, protected forms of dithiolene ligands.

Science.gov (United States)

Arumugam, Kuppuswamy; Bollinger, James E; Fink, Mark; Donahue, James P

2007-04-16

The reaction of P4S10 with acyloins, RC(O)CH(OH)R, in refluxing dioxane, followed by the addition of alkylating agents, forms dithiolene thiophosphoryl thiolate compounds, (R2C2S2)P(S)(SR'), which are readily isolated and purified. The compounds that have been prepared and identified spectroscopically are those with R = p-anisyl, R' = Me (1); R = p-anisyl, R' = Bz (2); R = Ph, R' = Me (4); R = Et, R' = Bz (5). Compounds 1, 2, and 4 were structurally characterized by X-ray crystallography and found to possess a tetrahedral coordination geometry about the phosphorus atom, with overall Cs symmetry. In each case, the mirror plane bisects the dithiolene S-P-S chelate and contains the thiophosphoryl bond, which ranges in length from 1.9241(8) to 1.9361(7) A. The use of 2-(bromomethyl)naphthalene as organic electrophile in the P4S10/acyloin reaction produced bis(2-methylnaphthalenyl) disulfide as the only identifiable product. The substitution of Lawesson's reagent for P4S10 in reactions with acyloins produced deoxy acyloin rather than products resulting from chalcogen exchange. Compounds 1-2 and 4-5 are Group 5 analogues of 1,3-dithiol-2-ones, (R2C2S2)C=O, and undergo a similar hydrolysis in aqueous base to liberate ene-1,2-dithiolate dianions from which corresponding metal dithiolene complexes may be prepared. Deprotection of 1 in MeO-/MeOH, followed by the addition of NiCl2.6H2O and then I2, produces square planar [Ni(S2C2(C6H4-p-OCH3)2)2] (8) in 93% yield. A high-resolution structure of 8 (P) reveals dithiolene C-C and C-S bond lengths that are clearly indicative of the thionyl radical monoanionic nature of the ligand. The use of isolated (R2C2S2)P(S)(SR') compounds as a dithiolene ligand source for the preparation of metal dithiolene complexes offers the advantages of clean reactivity and high yield.

Modified calcium oxide as stable solid base catalyst for Aldol ...

Indian Academy of Sciences (India)

A highly efficient and stable solid-base catalyst for Aldol condensation was ... was bonded on surface of CaO chemically and almost no Ca(OH)2 formed during the modification process. ... cation, corrosion and waste generation attract great.

Absence of hydrocortisone from cytoplasmic hormone-protein complexes formed in vivo after administration of biologically active doses of [3H] hydrocortisone

International Nuclear Information System (INIS)

Voigt, J.; Grote, H.; Sekeris, C.E.

1981-01-01

After administration of [ 3 H] hydrocortisone to adrenalectomized rats, hormone-protein complexes were isolated from liver cytosol by DEAE-cellulose chromatography. After application of biologically active and inactive doses of hydrocortisone five binding components were detected eluting at the same salt concentrations as the hormone-protein complexes observed after incubation of cytosol with [ 3 H] hydrocortisone in vitro. The isolated hormone-protein fractions were acidified and extracted with ethylacetate and the steroids were analyzed by thin-layer chromatography. No significant amount of hydrocortisone could be detected in any of the complexes formed in vivo 5-60 min after administration of biologically active doses of hydrocortisone. 3xi,11β,17α,20xi, 21-Pentahydroxypregnane, steroidal carboxy acids, glucuronides and a very polar conjugate of hydrocortisone were found in the different fractions. After an in vivo dose of hydrocortisone of about 1/5000th of the minimal dose required for enzyme induction, hydrocortisone could be found in all the cytoplasmic hormone-protein complexes formed. In contrast to the cytoplasmic hormone-protein complexes, hydrocortisone could be readily demonstrated in nuclei isolated after the administration of biologically active doses of hormone, although acid metabolites were found to represent the main part of the radioactive compounds present in the nuclei. These acid metabolites were located in the nuclear envelope. (orig.)

Development of Orodispersible Tablets of Candesartan Cilexetil-β-cyclodextrin Complex

Directory of Open Access Journals (Sweden)

Maddukuri Sravya

2013-01-01

Full Text Available The aim of this study was to investigate the use of inclusion complexation technique employing β-cyclodextrin in improving the dissolution profile of candesartan cilexetil, a BCS class-II drug, and to formulate the inclusion complex into orodispersible tablets. The inclusion complexes were formed by physical mixing, kneading, coevaporation, and lyophilisation methods. Inclusion complexes were characterized by FTIR, DSC, XRD, NMR, and mass spectral studies. Inclusion complexes prepared using kneading, and lyophilisation techniques in the molar ratio 1 : 5 with β-cyclodextrin were used for formulating orodispersible tablets by direct compression with different superdisintegrants like croscarmellose sodium, crospovidone, sodium starch glycolate, and low substituted hydroxypropyl cellulose in varying concentrations. The directly compressible powder was evaluated for precompression parameters, and the prepared orodispersible tablets were evaluated for postcompression parameters. Drug-excipient compatibility studies showed no interaction, and characterization proved the formation of inclusion complex. In vitro disintegration time was found to be within 3 minutes, and all the formulations showed complete drug release of 100% within 20 minutes. The optimized formulation was found to be stable after 6 months and showed no significant change in drug content. This work proved β-cyclodextrins to be effective solubilizing agent in improving the solubility of poorly water soluble drugs.

The Bonding of Pa to d8-ML3 Complexes

OpenAIRE

Kang, Sung-Kwon; Albright, Thomas A.; Silvestre, Jerome

1985-01-01

Extended Hiickel calculmions were carried out on 171, 'f/ 2, and 'f/3 complexes of P4 to Rh(PH3)2Cl. The 'f/ 1-square planar and an 'f/2 complex with C2v symmetry are the most stable. Geometrical optimizations and a detailed account of the bonding in each have been carried out. d10 'f/1-tetrahedral complexes of P4 are expected to be quite stable. The best candidate for an 'f/3 mode of bonding is the trimer Fe3(C0)9. Alternative complexes at 'f/3 include a d6-ML3 and d4-ML...

An air-stable copper reagent for nucleophilic trifluoromethylthiolation of aryl halides

KAUST Repository

Weng, Zhiqiang

2012-12-12

A series of copper(I) trifluoromethyl thiolate complexes have been synthesized from the reaction of CuF2 with Me3SiCF 3 and S8 (see scheme; Cu red, F green, N blue, S yellow). These air-stable complexes serve as reagents for the efficient conversion of a wide range of aryl halides into the corresponding aryl trifluoromethyl thioethers in excellent yields. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An air-stable copper reagent for nucleophilic trifluoromethylthiolation of aryl halides

KAUST Repository

Weng, Zhiqiang; He, Weiming; Chen, Chaohuang; Lee, Richmond; Tan, Davin; Lai, Zhiping; Kong, Dedao; Yuan, Yaofeng; Huang, Kuo-Wei

2012-01-01

A series of copper(I) trifluoromethyl thiolate complexes have been synthesized from the reaction of CuF2 with Me3SiCF 3 and S8 (see scheme; Cu red, F green, N blue, S yellow). These air-stable complexes serve as reagents for the efficient conversion of a wide range of aryl halides into the corresponding aryl trifluoromethyl thioethers in excellent yields. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Studies on electronic spectrum and electron spin resonance of vanadium (IV) complexes with organophosphorus compounds and high molecular weight amines

International Nuclear Information System (INIS)

Sato, Taichi; Nakamura, Takato

1981-01-01

In the extraction of vanadium (IV) from aqueous solutions containing hydrochloric acid and/or a mixture of hydrochloric acid and lithium chloride by bis(2-ethylhexyl) hydrogenphosphate (DEHPA; HX), trioctylmethylammonium chloride (Aliquat-336), trioctylamine (TOA), trioctylphosphine oxide (TOPO) and tributyl phosphate (TBP), the complexes formed in the organic phases have been examined by spectrophotometry and electron spin resonance spectroscopy. It is found that in the extraction by DEHPA, the vanadium in the organic phase exists as the monomeric species, VO(X 2 H) 2 , or the polymeric one, (VOX 2 )sub(n), and that in the extractions by Aliquat-336, TOA, TOPO, and TBP, tetravalent vanadium complexes are stable in the organic phases extracted from a mixed solution of hydrochloric acid and lithium chloride, while complexes containing pentavalent vanadium and VOV 4+ ions are formed in the organic phases extracted from hydrochloric acid solutions. (author)

Historical and contemporary stable isotope tracer approaches to studying mammalian protein metabolism

Science.gov (United States)

2016-01-01

Over a century ago, Frederick Soddy provided the first evidence for the existence of isotopes; elements that occupy the same position in the periodic table are essentially chemically identical but differ in mass due to a different number of neutrons within the atomic nucleus. Allied to the discovery of isotopes was the development of some of the first forms of mass spectrometers, driven forward by the Nobel laureates JJ Thomson and FW Aston, enabling the accurate separation, identification, and quantification of the relative abundance of these isotopes. As a result, within a few years, the number of known isotopes both stable and radioactive had greatly increased and there are now over 300 stable or radioisotopes presently known. Unknown at the time, however, was the potential utility of these isotopes within biological disciplines, it was soon discovered that these stable isotopes, particularly those of carbon (13C), nitrogen (15N), oxygen (18O), and hydrogen (2H) could be chemically introduced into organic compounds, such as fatty acids, amino acids, and sugars, and used to “trace” the metabolic fate of these compounds within biological systems. From this important breakthrough, the age of the isotope tracer was born. Over the following 80 yrs, stable isotopes would become a vital tool in not only the biological sciences, but also areas as diverse as forensics, geology, and art. This progress has been almost exclusively driven through the development of new and innovative mass spectrometry equipment from IRMS to GC‐MS to LC‐MS, which has allowed for the accurate quantitation of isotopic abundance within samples of complex matrices. This historical review details the development of stable isotope tracers as metabolic tools, with particular reference to their use in monitoring protein metabolism, highlighting the unique array of tools that are now available for the investigation of protein metabolism in vivo at a whole body down to a single protein level

Spectroscopic and structural study of the newly synthesized heteroligand complex of copper with creatinine and urea.

Science.gov (United States)

Gangopadhyay, Debraj; Singh, Sachin Kumar; Sharma, Poornima; Mishra, Hirdyesh; Unnikrishnan, V K; Singh, Bachcha; Singh, Ranjan K

2016-02-05

Study of copper complex of creatinine and urea is very important in life science and medicine. In this paper, spectroscopic and structural study of a newly synthesized heteroligand complex of copper with creatinine and urea has been discussed. Structural studies have been carried out using DFT calculations and spectroscopic analyses were carried out by FT-IR, Raman, UV-vis absorption and fluorescence techniques. The copper complex of creatinine and the heteroligand complex were found to have much increased water solubility as compared to pure creatinine. The analysis of FT-IR and Raman spectra helps to understand the coordination properties of the two ligands and to determine the probable structure of the heteroligand complex. The LIBS spectra of the heteroligand complex reveal that the complex is free from other metal impurities. UV-visible absorption spectra and the fluorescence emission spectra of the aqueous solution of Cu-Crn-urea heteroligand complex at different solute concentrations have been analyzed and the complex is found to be rigid and stable in its monomeric form at very low concentrations. Copyright © 2015 Elsevier B.V. All rights reserved.

Thermodynamic study of dihydrogen phosphate dimerisation and complexation with novel urea- and thiourea-based receptors.

Science.gov (United States)

Bregović, Nikola; Cindro, Nikola; Frkanec, Leo; Užarević, Krunoslav; Tomišić, Vladislav

2014-11-24

Complexation of dihydrogen phosphate by novel thiourea and urea receptors in acetonitrile and dimethyl sulfoxide was studied in detail by an integrated approach by using several methods (isothermal titration calorimetry, ESI-MS, and (1)H NMR and UV spectroscopy). Thermodynamic investigations into H2PO4(-) dimerisation, which is a process that has been frequently recognised, but rarely quantitatively described, were carried out as well. The corresponding equilibrium was taken into account in the anion-binding studies, which enabled reliable determination of the complexation thermodynamic quantities. In both solvents the thiourea derivatives exhibited considerably higher binding affinities with respect to those containing the urea moiety. In acetonitrile, 1:1 and 2:1 (anion/receptor) complexes formed, whereas in dimethyl sulfoxide only the significantly less stable complexes of 1:1 stoichiometry were detected. The solvent effects on the thermodynamic parameters of dihydrogen phosphate dimerisation and complexation reactions are discussed. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Polyphenol-Protein Complexes and Their Consequences for the Redox Activity, Structure and Function of Honey. A Current View and New Hypothesis – a Review

Directory of Open Access Journals (Sweden)

Brudzynski Katrina

2015-06-01

Full Text Available There is increasing evidence that protein complexation by honey polyphenols is changing honey structure and function. This relatively less investigated filed of honey research is presented in a context of known mechanism of formation of the stable polyphenol-protein complexes in other foods. At a core of these interactions lies the ability of polyphenols to form non-covalent and covalent bonds with proteins leading to transient and/or irreversible complexes, respectively. Honey storage and thermal processing induces non-enzymatic oxidation of polyphenols to reactive quinones and enables them to form covalent bonds with proteins. In this short review, we present data from our laboratory on previously unrecognized types of protein-polyphenol complexes that differed in size, stoichiometry, and antioxidant capacities, and the implications they have to honey antioxidant and antibacterial activities. Our intent is to provide a current understanding of protein-polyphenol complexation in honey and also some new thoughts /hypotheses that can be useful in directing future research.

Stability and properties of quasi-stable conformational states in the LH2 light-harvesting complex of Rbl. acidophilus bacteria formed by hexacoordination of bacteriochlorophyll a magnesium atom

Science.gov (United States)

Belov, Aleksandr S.; Khokhlov, Daniil V.; Glebov, Ilya O.; Poddubnyy, Vladimir V.; Eremin, Vadim V.

2017-06-01

Single-molecule spectroscopic experiments on several light-harvesting complexes revealed the existence of a set of metastable conformational states with different spectroscopic properties and lifetimes spanning from milliseconds to tens of seconds. In the absence of explicit structural data, a number of probable structural changes underlying the observed spectroscopic shifts were proposed. We examine the donor-acceptor interaction between the magnesium atom and the acetyl group of the adjacent bacteriochlorophylls a as a possible origin of metastable conformational states in the LH2 light-harvesting complex of Rbl. acidophilus bacteria. The results of QM/MM and molecular dynamics simulations show that such ligation can occur at room temperature and leads to one metastable coordination bond per pair of bacteriochlorophylls in the B850 ring. According to the results of Poisson-TrESP modeling, such coordination lowers the energies of the excited states of the complex by up to 163 cm-1 which causes red spectral shift of the B850 band.

Color stable manganese-doped phosphors

Science.gov (United States)

Lyons, Robert Joseph [Burnt Hills, NY; Setlur, Anant Achyut [Niskayuna, NY; Deshpande, Anirudha Rajendra [Twinsburg, OH; Grigorov, Ljudmil Slavchev [Sofia, BG

2012-08-28

A process for preparing color stable Mn.sup.+4 doped phosphors includes providing a phosphor of formula I; A.sub.x[MF.sub.y]:Mn.sup.+4 I and contacting the phosphor in particulate form with a saturated solution of a composition of formula II in aqueous hydrofluoric acid; A.sub.x[MF.sub.y]; II wherein A is Li, Na, K, Rb, Cs, NR.sub.4 or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; R is H, lower alkyl, or a combination thereof; x is the absolute value of the charge of the [MF.sub.y] ion; and y is 5, 6 or 7. In particular embodiments, M is Si, Ge, Sn, Ti, Zr, or a combination thereof. A lighting apparatus capable of emitting white light includes a semiconductor light source; and a phosphor composition radiationally coupled to the light source, and which includes a color stable Mn.sup.+4 doped phosphor.

Defect complexes formed with Ag atoms in CDTE, ZnTe, and ZnSe

CERN Document Server

Wolf, H; Ostheimer, V; Hamann, J; Lany, S; Wichert, T

2000-01-01

Using the radioactive acceptor $^{111}\\!$Ag for perturbed $\\gamma$-$\\gamma$-angular correlation (PAC) spectroscopy for the first time, defect complexes formed with Ag are investigated in the II-VI semiconductors CdTe, ZnTe and ZnSe. The donors In, Br and the Te-vacancy were found to passivate Ag acceptors in CdTe via pair formation, which was also observed in In-doped ZnTe. In undoped or Sb-doped CdTe and in undoped ZnSe, the PAC experiments indicate the compensation of Ag acceptors by the formation of double broken bond centres, which are characterised by an electric field gradient with an asymmetry parameter close to h = 1. Additionally, a very large electric field gradient was observed in CdTe, which is possibly connected with residual impurities.

Host-guest chemistry of dendrimer-drug complexes: 7. Formation of stable inclusions between acetylated dendrimers and drugs bearing multiple charges.

Science.gov (United States)

Fang, Min; Zhang, Jiahai; Wu, Qinglin; Xu, Tongwen; Cheng, Yiyun

2012-03-15

Drug molecules bearing multiple charges usually form precipitates with cationic dendrimers, which presents a challenge during the preparation of dendrimer inclusions for these drugs. In the present study, fully acetylated polyamidoamine (PAMAM) dendrimers were proposed as stable vehicles for drug molecules bearing two negative charges such as Congo red and indocyanine green. NMR techniques including (1)H NMR and (1)H-(1)H NOESY were used to characterize the host-guest chemistry of acetylated dendrimer and these guest molecules. The cationic PAMAM dendrimer was found to form a precipitate with Congo red and indocyanine green, but the acetylated one avoided the formation of cross-linking structures in aqueous solutions. NOESY studies revealed the encapsulation of Congo red and indocyanine green within the interior cavities of PAMAM dendrimers at mild acidic conditions and acetylated dendrimers show much stronger ability to encapsulate the guest molecules than cationic ones. Also, UV-vis-NIR studies suggest that acetylated dendrimers significantly improve the photostability of indocyanine green and prevent the formation of indocyanine green J-aggregates in aqueous solutions. The present study provides a new insight into dendrimer-based host-guest systems, especially for those guest molecules bearing multiple charges. © 2012 American Chemical Society

Supramolecular Complexes Formed by the Self-assembly of Hydrophobic Bis(Zn(2+)-cyclen) Complexes, Copper, and Di- or Triimide Units for the Hydrolysis of Phosphate Mono- and Diesters in Two-Phase Solvent Systems (Cyclen=1,4,7,10-Tetraazacyclododecane).

Science.gov (United States)

Hisamatsu, Yosuke; Miyazawa, Yuya; Yoneda, Kakeru; Miyauchi, Miki; Zulkefeli, Mohd; Aoki, Shin

2016-01-01

We previously reported on supramolecular complexes 4 and 5, formed by the 4 : 4 : 4 or 2 : 2 : 2 assembly of a dimeric zinc(II) complex (Zn2L(1)) having 2,2'-bipyridyl linker, dianion of cyanuric acid (CA) or 5,5-diethylbarbituric acid (Bar), and copper(II) ion (Cu(2+)) in an aqueous solution. The supermolecule 4 possesses Cu2(μ-OH)2 centers and catalyzes hydrolysis of phosphate monoester dianion, mono(4-nitrophenyl)phosphate (MNP), at neutral pH. In this manuscript, we report on design and synthesis of hydrophobic supermolecules 9 and 10 by 4 : 4 : 4 and 2 : 2 : 2 self-assembly of hydrophobic Zn2L(2) and Zn2L(3) containing long alkyl chains, CA or Bar, and Cu(2+) and their phosphatase activity for the hydrolysis of MNP and bis(4-nitrophenyl)phosphate (BNP) in two-phase solvent systems. We assumed that the Cu2(μ-OH)2 active sites of 9 and 10 would be more stable in organic solvent than in aqueous solution and that product inhibition of the supermolecules might be avoided by the release of HPO4(2-) into the aqueous layer. The findings indicate that 9 and 10 exhibit phosphatase activity in the two-phase solvent system, although catalytic turnover was not observed. Furthermore, the hydrolysis of BNP catalyzed by the hydrophobic 2 : 2 : 2 supermolecules in the two-phase solvent system is described.

Truncated forms of the prion protein PrP demonstrate the need for complexity in prion structure

Energy Technology Data Exchange (ETDEWEB)

Wan, William; Stöhr, Jan; Kendall, Amy; Stubbs, Gerald

2015-09-01

Self-propagation of aberrant protein folds is the defining characteristic of prions. Knowing the structural basis of self-propagation is essential to understanding prions and their related diseases. Prion rods are amyloid fibrils, but not all amyloids are prions. Prions have been remarkably intractable to structural studies, so many investigators have preferred to work with peptide fragments, particularly in the case of the mammalian prion protein PrP. We compared the structures of a number of fragments of PrP by X-ray fiber diffraction, and found that although all of the peptides adopted amyloid conformations, only the larger fragments adopted conformations that modeled the complexity of self-propagating prions, and even these fragments did not always adopt the PrP structure. It appears that the relatively complex structure of the prion form of PrP is not accessible to short model peptides, and that self-propagation may be tied to a level of structural complexity unobtainable in simple model systems. The larger fragments of PrP, however, are useful to illustrate the phenomenon of deformed templating (heterogeneous seeding), which has important biological consequences.

Truncated forms of the prion protein PrP demonstrate the need for complexity in prion structure.

Science.gov (United States)

Wan, William; Stöhr, Jan; Kendall, Amy; Stubbs, Gerald

2015-01-01

Self-propagation of aberrant protein folds is the defining characteristic of prions. Knowing the structural basis of self-propagation is essential to understanding prions and their related diseases. Prion rods are amyloid fibrils, but not all amyloids are prions. Prions have been remarkably intractable to structural studies, so many investigators have preferred to work with peptide fragments, particularly in the case of the mammalian prion protein PrP. We compared the structures of a number of fragments of PrP by X-ray fiber diffraction, and found that although all of the peptides adopted amyloid conformations, only the larger fragments adopted conformations that modeled the complexity of self-propagating prions, and even these fragments did not always adopt the PrP structure. It appears that the relatively complex structure of the prion form of PrP is not accessible to short model peptides, and that self-propagation may be tied to a level of structural complexity unobtainable in simple model systems. The larger fragments of PrP, however, are useful to illustrate the phenomenon of deformed templating (heterogeneous seeding), which has important biological consequences.

Supramolecular Complexes Formed in Systems Bile Salt-Bilirubin-Silica

Science.gov (United States)

Vlasova, N. N.; Severinovskaya, O. V.; Golovkova, L. P.

The formation of supramolecular complexes between bilirubin and primary micelles of bile salts has been studied. The association constants of bile salts and binding of bilirubin with these associates have been determined. The adsorption of bilirubin and bile salts from individual and mixed aqueous solutions onto hydrophobic silica surfaces has been investigated. The interaction of bilirubin with primary bile salt micelles and the strong retention in mixed micelles, which are supramolecular complexes, result in the adsorption of bilirubin in free state only.

Bayesian Modeling of Air Pollution Extremes Using Nested Multivariate Max-Stable Processes

KAUST Repository

Vettori, Sabrina; Huser, Raphaë l; Genton, Marc G.

2018-01-01

Capturing the potentially strong dependence among the peak concentrations of multiple air pollutants across a spatial region is crucial for assessing the related public health risks. In order to investigate the multivariate spatial dependence properties of air pollution extremes, we introduce a new class of multivariate max-stable processes. Our proposed model admits a hierarchical tree-based formulation, in which the data are conditionally independent given some latent nested $\\alpha$-stable random factors. The hierarchical structure facilitates Bayesian inference and offers a convenient and interpretable characterization. We fit this nested multivariate max-stable model to the maxima of air pollution concentrations and temperatures recorded at a number of sites in the Los Angeles area, showing that the proposed model succeeds in capturing their complex tail dependence structure.

Bayesian Modeling of Air Pollution Extremes Using Nested Multivariate Max-Stable Processes

KAUST Repository

Vettori, Sabrina

2018-03-18

Capturing the potentially strong dependence among the peak concentrations of multiple air pollutants across a spatial region is crucial for assessing the related public health risks. In order to investigate the multivariate spatial dependence properties of air pollution extremes, we introduce a new class of multivariate max-stable processes. Our proposed model admits a hierarchical tree-based formulation, in which the data are conditionally independent given some latent nested $\\\\alpha$-stable random factors. The hierarchical structure facilitates Bayesian inference and offers a convenient and interpretable characterization. We fit this nested multivariate max-stable model to the maxima of air pollution concentrations and temperatures recorded at a number of sites in the Los Angeles area, showing that the proposed model succeeds in capturing their complex tail dependence structure.

Neural-differentiated mesenchymal stem cells incorporated into muscle stuffed vein scaffold forms a stable living nerve conduit.

Science.gov (United States)

Hassan, Nur Hidayah; Sulong, Ahmad Fadzli; Ng, Min-Hwei; Htwe, Ohnmar; Idrus, Ruszymah B H; Roohi, Sharifah; Naicker, Amaramalar S; Abdullah, Shalimar

2012-10-01

Autologous nerve grafts to bridge nerve gaps have donor site morbidity and possible neuroma formation resulting in development of various methods of bridging nerve gaps without using autologous nerve grafts. We have fabricated an acellular muscle stuffed vein seeded with differentiated mesenchymal stem cells (MSCs) as a substitute for nerve autografts. Human vein and muscle were both decellularized by liquid nitrogen immersion with subsequent hydrolysis in hydrochloric acid. Human MSCs were subjected to a series of treatments with a reducing agent, retinoic acid, and a combination of trophic factors. The differentiated MSCs were seeded on the surface of acellular muscle tissue and then stuffed into the vein. Our study showed that 35-75% of the cells expressed neural markers such as S100b, glial fibrillary acidic protein (GFAP), p75 NGF receptor, and Nestin after differentiation. Histological and ultra structural analyses of muscle stuffed veins showed attachment of cells onto the surface of the acellular muscle and penetration of the cells into the hydrolyzed fraction of muscle fibers. We implanted these muscle stuffed veins into athymic mice and at 8 weeks post-implantation, the acellular muscle tissue had fully degraded and replaced with new matrix produced by the seeded cells. The vein was still intact and no inflammatory reactions were observed proving the biocompatibility and biodegradability of the conduit. In conclusion, we have successfully formed a stable living nerve conduit which may serve as a substitute for autologous nerves. Copyright © 2012 Orthopaedic Research Society.

Secondary Waste Form Down-Selection Data Package—Fluidized Bed Steam Reforming Waste Form

Energy Technology Data Exchange (ETDEWEB)

Qafoku, Nikolla; Westsik, Joseph H.; Strachan, Denis M.; Valenta, Michelle M.; Pires, Richard P.

2011-09-12

The Hanford Site in southeast Washington State has 56 million gallons of radioactive and chemically hazardous wastes stored in 177 underground tanks (ORP 2010). The U.S. Department of Energy (DOE), Office of River Protection (ORP), through its contractors, is constructing the Hanford Tank Waste Treatment and Immobilization Plant (WTP) to convert the radioactive and hazardous wastes into stable glass waste forms for disposal. Within the WTP, the pretreatment facility will receive the retrieved waste from the tank farms and separate it into two treated process streams. These waste streams will be vitrified, and the resulting waste canisters will be sent to offsite (high-level waste [HLW]) and onsite (immobilized low-activity waste [ILAW]) repositories. As part of the pretreatment and ILAW processing, liquid secondary wastes will be generated that will be transferred to the Effluent Treatment Facility (ETF) on the Hanford Site for further treatment. These liquid secondary wastes will be converted to stable solid waste forms that will be disposed of in the Integrated Disposal Facility (IDF). To support the selection of a waste form for the liquid secondary wastes from WTP, Washington River Protection Solutions (WRPS) has initiated secondary waste form testing work at Pacific Northwest National Laboratory (PNNL). In anticipation of a down-selection process for a waste form for the Solidification Treatment Unit to be added to the ETF, PNNL is developing data packages to support that down-selection. The objective of the data packages is to identify, evaluate, and summarize the existing information on the four waste forms being considered for stabilizing and solidifying the liquid secondary wastes. At the Hanford Site, the FBSR process is being evaluated as a supplemental technology for treating and immobilizing Hanford LAW radioactive tank waste and for treating secondary wastes from the WTP pretreatment and LAW vitrification processes.

Water-soluble tetrapodal N, O ligands incorporating soft N-heterocycles for the selective complexation of Am(III) over Ln(III)

Energy Technology Data Exchange (ETDEWEB)

Heitzmann, M.; Gateau, Ch.; Delangle, P. [CEA Grenoble, Inac, Service de Chimie Inorganique et Biologique, UMR E 3 CEA UJF, FRE CNRS 3200, F-38054 Grenoble (France); Chareyre, L.; Miguirditchian, M.; Charbonnel, M.Ch. [CEA Marcoule, DEN, DRCP, SCPS, F-30207, Bagnols-sur-Ceze (France)

2010-07-01

A series of four water-soluble N, O-tetrapodal ligands derived from ethylenediamine, bearing hard acetate groups and soft N-heterocycles, either pyridine or pyrazine, was developed to study the impact of the softness of N-donors on the complexation properties with trivalent f ions. Two novel ligands of enhanced soft character, bearing three pyridines (L{sup 3py}) or three pyrazines (L{sup 3pz}), were synthesized and the related lanthanide complexes were studied in solution. The ligand containing three pyridyl-methyl moieties L{sup 3py} gives complexes with a coordination similar to EDTA, i.e. a hexa-dentate coordination mode as indicated by NMR and luminescence decays (q = 3) and stability constants in the range log {beta}{sub 110} = 6.99-9.3 (La-Lu). On the other hand, the softest molecule L{sup 3pz} forms much less stable complexes with log {beta}{sub 110} = 4.0-4.4 (La-Eu). The selective back-extraction of Am(III) from organic solutions containing 4f and 5f elements was tested with the four water-soluble complexing agents. The ligand L{sup 3pz} demonstrates poor stripping ability and selectivity. In contrast, the three ligands L{sup py}, L{sup pz} and L{sup 3py} give interesting back-extraction results with Eu/Am separation factors ranging from 36 to 46, which are significantly higher than with HEDTA. This exemplifies the role of the N-hetero-cycle softness in enhancing the separation between Am(III) and Eu(III). Interestingly, the pyrazine-based ligand, L{sup pz}, demonstrates the best stripping properties, with a distribution factor that approaches that of HEDTA in the same conditions (D{sub Am{approx}}0.3). This molecule is a good compromise between softness and hardness and forms complexes still stable at pH 3 due to its low basicity. (authors)

Stable isotope-resolved metabolomics and applications for drug development

Science.gov (United States)

Fan, Teresa W-M.; Lorkiewicz, Pawel; Sellers, Katherine; Moseley, Hunter N.B.; Higashi, Richard M.; Lane, Andrew N.

2012-01-01

Advances in analytical methodologies, principally nuclear magnetic resonance spectroscopy (NMR) and mass spectrometry (MS), during the last decade have made large-scale analysis of the human metabolome a reality. This is leading to the reawakening of the importance of metabolism in human diseases, particularly cancer. The metabolome is the functional readout of the genome, functional genome, and proteome; it is also an integral partner in molecular regulations for homeostasis. The interrogation of the metabolome, or metabolomics, is now being applied to numerous diseases, largely by metabolite profiling for biomarker discovery, but also in pharmacology and therapeutics. Recent advances in stable isotope tracer-based metabolomic approaches enable unambiguous tracking of individual atoms through compartmentalized metabolic networks directly in human subjects, which promises to decipher the complexity of the human metabolome at an unprecedented pace. This knowledge will revolutionize our understanding of complex human diseases, clinical diagnostics, as well as individualized therapeutics and drug response. In this review, we focus on the use of stable isotope tracers with metabolomics technologies for understanding metabolic network dynamics in both model systems and in clinical applications. Atom-resolved isotope tracing via the two major analytical platforms, NMR and MS, has the power to determine novel metabolic reprogramming in diseases, discover new drug targets, and facilitates ADME studies. We also illustrate new metabolic tracer-based imaging technologies, which enable direct visualization of metabolic processes in vivo. We further outline current practices and future requirements for biochemoinformatics development, which is an integral part of translating stable isotope-resolved metabolomics into clinical reality. PMID:22212615

Proton NMR study of the influence of heme vinyl groups on the formation of the isomeric forms of sulfmyoglobin

International Nuclear Information System (INIS)

Chatfield, M.J.; La Mar, G.N.; Balch, A.L.; Smith, K.M.; Parish, D.W.; LePage, T.J.

1986-01-01

The formation of sulfmyoglobin has been investigated for myoglobin reconstituted with hemins having vinyls replaced by hydrogens to determine the participation of the vinyl groups in the reaction processes. Green complexes are produced in all cases, proving that vinyls are not obligatory for the formation of sulfproteins. In the presence of the 4-vinyl group, the 1 H NMR spectra of the met-cyano derivatives indicate the formation of three green species; however, the most stable of these products is not formed in the absence of this group, confirming reaction of the 4-vinyl in this species. Two new red extractable sulfmyoglobin derivatives are formed in the absence of the 4-vinyl group. (Auth.)

Synthesis and structure determination of a stable organometallic uranium(V) imine complex and its isolobal anionic U(IV)-ate complex

Energy Technology Data Exchange (ETDEWEB)

Sharma, M.; Botoshanskii, M.; Eisen, M.S. [Schulich Faculty of Chemistry, and Institute of Catalysis Science and Technology, Technion Israel Institute of Technology, Haifa (Israel); Bannenberg, Th.; Tamm, M. [Institut fur Anorganische und Analytische Chemie, Technische Universitat Braunschweig (Germany)

2010-06-15

The reaction of one equivalent of Cp*{sub 2}UCl{sub 2} with 2-(trimethylsilyl-imino)-1,3-di-tert-butyl-imidazoline in boiling toluene afforded a one electron oxidation of the uranium metal and the opening of the N-heterocyclic ring, resulting in the formation of an organometallic uranium(V) imine complex. This complex crystallized with one molecule of toluene in the unit cell, and its solid-state structure was determined by X-ray diffraction analysis. When the same reaction was performed in perdeuterated toluene, a myriad of organometallic complexes were obtained, however, when equimolar amounts of water were used in toluene, the same complex was obtained, and its solid state characterization shows two independent molecules in the unit cell with an additional water molecule. For comparison of the geometric parameters, the corresponding isolobal anionic uranium(IV) complex [Cp*{sub 2}UCl{sub 3}]{sup -} was synthesized by the reaction of Cp*{sub 2}UCl{sub 2} with 1,3-di-tert-butyl-imidazolium chloride, and the resulting U(IV)-ate complex was characterized by X-ray diffraction analysis. (authors)

An Automated Approach to Very High Order Aeroacoustic Computations in Complex Geometries

Science.gov (United States)

Dyson, Rodger W.; Goodrich, John W.

2000-01-01

Computational aeroacoustics requires efficient, high-resolution simulation tools. And for smooth problems, this is best accomplished with very high order in space and time methods on small stencils. But the complexity of highly accurate numerical methods can inhibit their practical application, especially in irregular geometries. This complexity is reduced by using a special form of Hermite divided-difference spatial interpolation on Cartesian grids, and a Cauchy-Kowalewslci recursion procedure for time advancement. In addition, a stencil constraint tree reduces the complexity of interpolating grid points that are located near wall boundaries. These procedures are used to automatically develop and implement very high order methods (>15) for solving the linearized Euler equations that can achieve less than one grid point per wavelength resolution away from boundaries by including spatial derivatives of the primitive variables at each grid point. The accuracy of stable surface treatments is currently limited to 11th order for grid aligned boundaries and to 2nd order for irregular boundaries.

Lewis Acid Assisted Nitrate Reduction with Biomimetic Molybdenum Oxotransferase Complex.

Science.gov (United States)

Elrod, Lee Taylor; Kim, Eunsuk

2018-03-05

The reduction of nitrate (NO 3 - ) to nitrite (NO 2 - ) is of significant biological and environmental importance. While Mo IV (O) and Mo VI (O) 2 complexes that mimic the active site structure of nitrate reducing enzymes are prevalent, few of these model complexes can reduce nitrate to nitrite through oxygen atom transfer (OAT) chemistry. We present a novel strategy to induce nitrate reduction chemistry of a previously known catalyst Mo IV (O)(SN) 2 (2), where SN = bis(4- tert-butylphenyl)-2-pyridylmethanethiolate, that is otherwise incapable of achieving OAT with nitrate. Addition of nitrate with the Lewis acid Sc(OTf) 3 (OTf = trifluoromethanesulfonate) to 2 results in an immediate and clean conversion of 2 to Mo VI (O) 2 (SN) 2 (1). The Lewis acid additive further reacts with the OAT product, nitrite, to form N 2 O and O 2 . This work highlights the ability of Sc 3+ additives to expand the reactivity scope of an existing Mo IV (O) complex together with which Sc 3+ can convert nitrate to stable gaseous molecules.

A novel form of the RelA nuclear factor kappaB subunit is induced by and forms a complex with the proto-oncogene c-Myc.

Science.gov (United States)

Chapman, Neil R; Webster, Gill A; Gillespie, Peter J; Wilson, Brian J; Crouch, Dorothy H; Perkins, Neil D

2002-01-01

Members of both Myc and nuclear factor kappaB (NF-kappaB) families of transcription factors are found overexpressed or inappropriately activated in many forms of human cancer. Furthermore, NF-kappaB can induce c-Myc gene expression, suggesting that the activities of these factors are functionally linked. We have discovered that both c-Myc and v-Myc can induce a previously undescribed, truncated form of the RelA(p65) NF-kappaB subunit, RelA(p37). RelA(p37) encodes the N-terminal DNA binding and dimerization domain of RelA(p65) and would be expected to function as a trans-dominant negative inhibitor of NF-kappaB. Surprisingly, we found that RelA(p37) no longer binds to kappaB elements. This result is explained, however, by the observation that RelA(p37), but not RelA(p65), forms a high-molecular-mass complex with c-Myc. These results demonstrate a previously unknown functional and physical interaction between RelA and c-Myc with many significant implications for our understanding of the role that both proteins play in the molecular events underlying tumourigenesis. PMID:12027803

Complexation of vanadium with amidoxime and carboxyl groups. Uncovering the competitive role of vanadium in uranium extraction from seawater

Energy Technology Data Exchange (ETDEWEB)

Wang, Cong-Zhi; Wu, Qun-Yan; Lan, Jian-Hui; Shi, Wei-Qun [Chinese Academy of Sciences, Beijing (China). Inst. of High Energy Physics; Chai, Zhi-Fang [Chinese Academy of Sciences, Beijing (China). Inst. of High Energy Physics; Soochow Univ., Suzhou (China). School of Radiological and Interdisciplinary Sciences (RAD-X); Wu, Guo-Zhong [Chinese Academy of Sciences, Shanghai (China). Shanghai Inst. of Applied Physics

2017-09-01

At present, amidoxime-based adsorbents are considered to be the most promising materials for extraction of uranium from seawater. However, the high concentrations of transition metals especially vanadium strongly compete with uranium in the sequestration process, which is extremely limited the commercial use of amidoxime-based adsorbents. In this work, the coordination modes, bonding nature, and stabilities of possible vanadium(IV) (VO{sup 2+}) and (V) (VO{sub 2}{sup +}, VO{sup 3+}, V{sup 5+}) complexes with amidoximate (AO{sup -}), carboxyl (Ac{sup -}), glutarimidedioximate (HA{sup -}) and deprotonated glutarimidedioximate (A{sup 2-}) on single and double alkyl chains (R=C{sub 13}H{sub 26}) are systematically explored by quantum chemical calculations. Different from the uranyl (UO{sub 2}{sup 2+}) complexes, the AO{sup -} groups of the vanadium(IV) and (V) complexes prefer to coordinate as monodentate and chelate ligands, while few species with AO{sup -} groups in η{sup 2}-binding mode have been observed in the vanadium complexes. Besides, the vanadium complexes are predicted to have obvious covalent metal-ligand bonds. According to thermodynamic stability analysis, all the vanadium complexes with AO{sup -}, Ac{sup -}, HA{sup -} and A{sup 2-} ligands on double alkyl chains are found to be more stable than corresponding complexes with ligands on a single chain. The synergistic effect of the amidoxime and carboxyl groups can be observed in most of VO{sub 2}{sup +} and VO{sup 3+} complexes with mixed ligands (AO{sup -}/Ac{sup -}). The vanadium(IV) and (V) complexes are more stable than the corresponding uranyl complexes, and the adsorption capability of the amidoxime-based adsorbents toward vanadium(V) ions decrease in the order of VO{sub 2}{sup +}>VO{sup 3+}> V{sup 5+}. The dioxovanadium cation VO{sub 2}{sup +} is predicted to form multinuclear vanadium complex in the sequestration process, possibly resulting in higher stable VO{sub 2}{sup +} complexes. Therefore

Complexes formed by cadmium and chelating agents in plants

International Nuclear Information System (INIS)

Strasdeit, H.; Duhme, A.K.; Johanning, J.

1993-01-01

Measurements of X-ray absorption spectrums and potentiometric titrations yield some information on the basic complexforming properties of phytochelates. Cadmium-phytochelate complexes are extremely variable as regards composition and structure. This is evident from the fact that the metal's coordination environment (sulphur or oxygen coordination) is dependent uopn pH values. At pH values of about 7 it is normal to find Cd(SCys) 4 units. Given the availability of an adequate number of ligands, these are seen to occur as solitary units even in multinucleate complexes. (orig.) [de

Nanoparticulate Tubular Immunostimulating Complexes: Novel Formulation of Effective Adjuvants and Antigen Delivery Systems

Directory of Open Access Journals (Sweden)

Nina Sanina

2017-01-01

Full Text Available New generation vaccines, based on isolated antigens, are safer than traditional ones, comprising the whole pathogen. However, major part of purified antigens has weak immunogenicity. Therefore, elaboration of new adjuvants, more effective and safe, is an urgent problem of vaccinology. Tubular immunostimulating complexes (TI-complexes are a new type of nanoparticulate antigen delivery systems with adjuvant activity. TI-complexes consist of cholesterol and compounds isolated from marine hydrobionts: cucumarioside A2-2 (CDA from Cucumaria japonica and monogalactosyldiacylglycerol (MGDG from marine algae or seagrass. These components were selected due to immunomodulatory and other biological activities. Glycolipid MGDG from marine macrophytes comprises a high level of polyunsaturated fatty acids (PUFAs, which demonstrate immunomodulatory properties. CDA is a well-characterized individual compound capable of forming stable complex with cholesterol. Such complexes do not possess hemolytic activity. Ultralow doses of cucumariosides stimulate cell as well as humoral immunity. Therefore, TI-complexes comprising biologically active components turned out to be more effective than the strongest adjuvants: immunostimulating complexes (ISCOMs and complete Freund’s adjuvant. In the present review, we discuss results published in series of our articles on elaboration, qualitative and quantitative composition, ultrastructure, and immunostimulating activity of TI-complexes. The review allows immersion in the history of creating TI-complexes.

Study of relaxation processes in 'metal-ligand' complexes after electron capture decay using the 111In isotope as an example

International Nuclear Information System (INIS)

Shpinkova, L.G.; Golubeva, A.S.; Ryasny, O.K.; Nikitin, S.M.; Sorokin, A.A.; Uzbyakova, A.S.

2003-01-01

Full text: Complexes of metals with organic ligands are widely used in different scientific and industrial applications, such as analytical chemistry, oil production and refinery, power engineering, water treatment, agriculture, etc. Several hundred complexes are commercially available and there are still intensive works on synthesizing new complexones in order to obtain complexes with required properties. In this connection, it is important to investigate the molecular characteristics of complexes and their structures and correlate with their properties. One of the methods, which proved to provide useful information about metal-ligand complexes behaviour, is the method of time differential perturbed angular γγ-correlation (Tdpa). Numerous works have been devoted to studies of different complexes by this technique. In the Inst. of Nuclear Physics, Lomonosov Moscow State Univ., Moscow, this method was applied to studies of electron capture (EC) after-effects and their influence on the indium-ligand complexes in aqueous solutions. The present work is devoted to studies of relaxation processes in daughter 111 Cd-ligand complexes formed after 111 In EC decay. EC leaves a hole in an inner electronic shell of the daughter atom, which is followed by Auger-process. This process leads to a highly excited state of a daughter atom, which either causes disintegration of a complex into small fragments or relaxation to a stable complex with the daughter atom. TDPAC measurements were performed for a number of 111 In-complexes with acetic and phosphonic ligands. All measurements were performed for neutral aqueous solutions of complexes at room temperature. Three types of molecules containing radioactive daughter 11C d atoms were observed after 111 In decay for all studied complexes. One fraction corresponds to the intact complexes, the second one - to fully disintegrated complexes. The third fraction was characterized by a fast relaxation parameter indicating high transient

The Crc and Hfq proteins of Pseudomonas putida cooperate in catabolite repression and formation of ribonucleic acid complexes with specific target motifs.

Science.gov (United States)

Moreno, Renata; Hernández-Arranz, Sofía; La Rosa, Ruggero; Yuste, Luis; Madhushani, Anjana; Shingler, Victoria; Rojo, Fernando

2015-01-01

The Crc protein is a global regulator that has a key role in catabolite repression and optimization of metabolism in Pseudomonads. Crc inhibits gene expression post-transcriptionally, preventing translation of mRNAs bearing an AAnAAnAA motif [the catabolite activity (CA) motif] close to the translation start site. Although Crc was initially believed to bind RNA by itself, this idea was recently challenged by results suggesting that a protein co-purifying with Crc, presumably the Hfq protein, could account for the detected RNA-binding activity. Hfq is an abundant protein that has a central role in post-transcriptional gene regulation. Herein, we show that the Pseudomonas putida Hfq protein can recognize the CA motifs of RNAs through its distal face and that Crc facilitates formation of a more stable complex at these targets. Crc was unable to bind RNA in the absence of Hfq. However, pull-down assays showed that Crc and Hfq can form a co-complex with RNA containing a CA motif in vitro. Inactivation of the hfq or the crc gene impaired catabolite repression to a similar extent. We propose that Crc and Hfq cooperate in catabolite repression, probably through forming a stable co-complex with RNAs containing CA motifs to result in inhibition of translation initiation. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.

Determination of the stability of the uranyl ion sipped in τ-hydrogen phosphate of zirconium in sodic form

International Nuclear Information System (INIS)

Ordonez R, E.; Fernandez V, S.M.; Drot, R.; Simoni, E.

2005-01-01

The stability of the uranyl sipped in the zirconium τ-hydrogen phosphate in sodic form (τ-NaZrP), was carried out characterizing the complexes formed by Laser spectroscopy in the visible region and by X-ray photoelectron spectroscopy. The material was prepared by a new synthesis technique working in nitrogen atmosphere and to low temperatures. The sorption of the uranyl ion was made in acid media with concentrations of 10 -4 and 10 -5 of uranyl nitrate and with ion forces of 0.1 and 0.5 M of NaClO 4 . The spectra of induced fluorescence with laser (TRLFS) show that the uranyl is fixed in very acid media in three well differentiated species, to pH less acid, the specie of long half life disappears and are only those of short half life. The results of the binding energy obtained by XPS indicate that the binding energy of the uranyl confer it a stable character to the complex formed in the τ-NaZP, that makes to this material appropriate to retain to the uranyl in solution to high ion forces and in acid media. (Author)

Cyclodextrin based ternary system of modafinil: Effect of trimethyl chitosan and polyvinylpyrrolidone as complexing agents.

Science.gov (United States)

Patel, Parth; Agrawal, Y K; Sarvaiya, Jayrajsinh

2016-03-01

Modafinil is an approved drug for the treatment of narcolepsy and have a strong market presence in many countries. The drug is widely consumed for off-label uses and currently listed as a restricted drug. Modafinil has very low water solubility. To enhance the aqueous solubility of modafinil by the formation of a ternary complex with Hydroxypropyl-β-cyclodextrin and two hydrophilic polymers was the main objective of the present study. Pyrrolidone (PVP K30) and a water soluble chitosan derivative, trimethyl chitosan (TMC) were studied by solution state and solid state characterization methods for their discriminatory efficiency in solubility enhancement of modafinil. Phase solubility study depicted the highest complexation efficiency (2.22) of cyclodextrin derivative in the presence of TMC compared to the same in the presence of PVP K30 (0.08) and in the absence of any polymer (0.92). FT-IR analysis of binary and ternary complex expressed comparable contribution of both polymers in formation of inclusion complex. The thermal behaviour of binary and ternary complex, involving individual polymers disclosed the influence of TMC on polymorphism of the drug. DSC study revealed efficiency of TMC to prevent conversion of metastable polymorphic form to stable polymorphic form. Ternary complex, involving TMC enhanced water solubility of the drug 1.5 times more compared to the binary complex of the drug whereas PVP K30 reduced the Solubility. Copyright © 2015 Elsevier B.V. All rights reserved.

Latest developments at GANIL for stable and radioactive ion beam production

International Nuclear Information System (INIS)

Jardin, P.; Barue, C.; Bajeat, O.; Canet, C.; Clement, E.; Cornell, J. C.; Delahaye, P.; Dubois, M.; Dupuis, M.; Flambard, J. L.; Fraanberg, H.; Frigot, R.; Leboucher, C.; Lecesne, N.; Lecomte, P.; Leherissier, P.; Lemagnen, F.; Leroy, R.; Maunoury, L.; Mery, A.

2010-01-01

In the frame of the SPIRAL II (Systeme de Production d'Ions Radioactifs Acceleres en Ligne Partie II) project, several developments of stable and radioactive ion production systems have been started up. In parallel, GANIL has the ambition to preserve the existing stable and radioactive beams and also to increase its range by offering new ones. In order to identify the best directions for this development, a new group called GANISOL has been formed. Its preliminary conclusions and the latest developments at GANIL are presented.

Crystal structure of the Csm3-Csm4 subcomplex in the type III-A CRISPR-Cas interference complex.

Science.gov (United States)

Numata, Tomoyuki; Inanaga, Hideko; Sato, Chikara; Osawa, Takuo

2015-01-30

Clustered, regularly interspaced, short palindromic repeat (CRISPR) loci play a pivotal role in the prokaryotic host defense system against invading genetic materials. The CRISPR loci are transcribed to produce CRISPR RNAs (crRNAs), which form interference complexes with CRISPR-associated (Cas) proteins to target the invading nucleic acid for degradation. The interference complex of the type III-A CRISPR-Cas system is composed of five Cas proteins (Csm1-Csm5) and a crRNA, and targets invading DNA. Here, we show that the Csm1, Csm3, and Csm4 proteins from Methanocaldococcus jannaschii form a stable subcomplex. We also report the crystal structure of the M. jannaschii Csm3-Csm4 subcomplex at 3.1Å resolution. The complex structure revealed the presence of a basic concave surface around their interface, suggesting the RNA and/or DNA binding ability of the complex. A gel retardation analysis showed that the Csm3-Csm4 complex binds single-stranded RNA in a non-sequence-specific manner. Csm4 structurally resembles Cmr3, a component of the type III-B CRISPR-Cas interference complex. Based on bioinformatics, we constructed a model structure of the Csm1-Csm4-Csm3 ternary complex, which provides insights into its role in the Csm interference complex. Copyright © 2014 Elsevier Ltd. All rights reserved.

Thermally Stable Ni-rich Austenite Formed Utilizing Multistep Intercritical Heat Treatment in a Low-Carbon 10 Wt Pct Ni Martensitic Steel

Science.gov (United States)

Jain, Divya; Isheim, Dieter; Zhang, Xian J.; Ghosh, Gautam; Seidman, David N.

2017-08-01

Austenite reversion and its thermal stability attained during the transformation is key to enhanced toughness and blast resistance in transformation-induced-plasticity martensitic steels. We demonstrate that the thermal stability of Ni-stabilized austenite and kinetics of the transformation can be controlled by forming Ni-rich regions in proximity of pre-existing (retained) austenite. Atom probe tomography (APT) in conjunction with thermodynamic and kinetic modeling elucidates the role of Ni-rich regions in enhancing growth kinetics of thermally stable austenite, formed utilizing a multistep intercritical ( Quench- Lamellarization- Tempering (QLT)-type) heat treatment for a low-carbon 10 wt pct Ni steel. Direct evidence of austenite formation is provided by dilatometry, and the volume fraction is quantified by synchrotron X-ray diffraction. The results indicate the growth of nm-thick austenite layers during the second intercritical tempering treatment (T-step) at 863 K (590 °C), with austenite retained from first intercritical treatment (L-step) at 923 K (650 °C) acting as a nucleation template. For the first time, the thermal stability of austenite is quantified with respect to its compositional evolution during the multistep intercritical treatment of these steels. Austenite compositions measured by APT are used in combination with the thermodynamic and kinetic approach formulated by Ghosh and Olson to assess thermal stability and predict the martensite-start temperature. This approach is particularly useful as empirical relations cannot be extrapolated for the highly Ni-enriched austenite investigated in the present study.

Probing the lowest coordination number of dianionic platinum-cyanide complexes in the gas phase: Dynamics of the charge dissociation process

DEFF Research Database (Denmark)

Bojesen, G; Hvelplund, P; Jørgensen, Thomas J. D.

2000-01-01

Low-energy and high-energy collision induced dissociation techniques are used to study the dissociation behavior of the gaseous Pt(CN)(6)(2-) and Pt(CN)(4)(2-) dianion complexes in order to probe the smallest stable dianion complex. Loss of neutral molecules from Pt(CN)(6)(2-) occurs resulting...... in Pt(CN)(5)(2-) and Pt(CN)(4)(2-), but no indication of the existence of Pt(CN)(3)(2-) was found. This indicates that the lifetime of Pt(CN)(3)(2-) is less than 4 mus (the flight time from the collision region to the detector). In contrast, all monoanion platinum-cyanide complexes were observed, i.......e., Pt(CN)(n)(-) (n=1-6). The kinetic energy released in processes where monoanions are formed is much lower than the barrier height for the reverse reaction (>1.5 eV), which indicates that electron detachment is involved, e.g., Pt(CN)(3)(-) and CN- are not formed in the same dynamical process from Pt(CN...

Silver(I) and copper(I) complexes with the closo-decaborate anion B10H102- as a ligand

International Nuclear Information System (INIS)

Malinina, E.A.; Zhizhin, K.Yu.; Polyakova, I.N.; Lisovskij, M.V.; Kuznetsov, N.T.

2002-01-01

Studying the process of silver(I) and copper(I) complexing with closo-borate anion B 10 H 10 2- it is determined that the last can to play a role of intraspherical ligand forming stable coordination compounds of two types: Cat[MB 10 H 10 ] and [M 2 B 10 H 10 ] (M=Ag(I), Cu(I)). In these compounds the bond metal-boron skeleton is realized by means of formation of three-center bonds M-H-B. Structure of the complexes Cs[AgB 10 H 10 ] and [(C 2 H 5 ) 3 NH][AgB 10 H 10 ] and possible mechanism of their formation are discussed [ru

Pseudosatellite technologies based on the use of functionally stable complexes of remote-piloted aircrafts

Science.gov (United States)

Mashkov, O. A.; Samborskiy, I. I.

2009-10-01

A bundle of papers dealing with functionally stable systems requires the necessity of analyzing of obtained results and their understanding in a general context of cybernetic's development and applications. Description of this field of science, main results and perspectives of the new theory of functionally stability of dynamical systems concerning the problem of remote-piloted aircrafts engineering using pseudosatellite technologies are proposed in the paper.

Thermodynamic parameters of the complexation of uranyl(VI) by diethylenetriamine in dimethyl sulfoxide

International Nuclear Information System (INIS)

Cassol, A.; Bernardo, P. di; Portanova, R.; Tolazzi, M.; Tomat, G.; Zanonato, P.L.

1993-01-01

The changes in free energy, enthalpy, and entropy for the complex formation reactions between uranyl(VI) ion and diethylenetriamine (dien) in dimethyl sulfoxide have been determined by potentiometric and calorimetric measurements at 25 C in a medium of ionic strength 0.1 mol dm -3 . The amine forms a very stable 1:1 complex which results stabilized only by the highly favourable enthalpy change. Entropy change is negative and opposes the reaction. The comparison of the thermodynamic data concerning complexation of uranyl(VI) by charged and uncharged ligands reveals that in this case (uncharged ligand) the enthalpy contribution is mainly related to the formation of the metal-ligand bonds while the entropy term might be associated with the decrease in the translational and conformational entropy occurring in the complexation of the ligand. FTIR and calorimetric measurements have been carried out to study the effect of traces of water on the equilibria in solution. It has been found that water can interfere in the complexation reaction giving rise to the formation of a dinuclear hydroxo complex in which probably two μ 2 -OH bridges link two monomer moieties. (orig.)

On the symmetric α-stable distribution with application to symbol error rate calculations

KAUST Repository

Soury, Hamza

2016-12-24

The probability density function (PDF) of the symmetric α-stable distribution is investigated using the inverse Fourier transform of its characteristic function. For general values of the stable parameter α, it is shown that the PDF and the cumulative distribution function of the symmetric stable distribution can be expressed in terms of the Fox H function as closed-form. As an application, the probability of error of single input single output communication systems using different modulation schemes with an α-stable perturbation is studied. In more details, a generic formula is derived for generalized fading distribution, such as the extended generalized-k distribution. Later, simpler expressions of these error rates are deduced for some selected special cases and compact approximations are derived using asymptotic expansions.

New Polymorphic Forms of Pemetrexed Diacid and Their Use for the Preparation of Pharmaceutically Pure Amorphous and Hemipentahydrate Forms of Pemetrexed Disodium

OpenAIRE

Michalak, Olga; Łaszcz, Marta; Jatczak, Kamil; Witkowska, Anna; Bujak, Iwona; Groman, Aleksandra; Cybulski, Marcin

2015-01-01

The preparation of stable amorphous pemetrexed disodium of pharmaceutical purity as well as the process optimization for the preparation of the hemipentahydrate form of pemetrexed disodium are described. Analytical methods for the polymorphic and chemical purity studies of pemetrexed disodium and pemetrexed diacid forms were developed. The physicochemical properties of the amorphous and hydrate forms of pemetrexed disodium, as well as new forms of pemetrexed diacid (a key synthetic intermedia...

Thermal and electrical conductivity enhancement of graphite nanoplatelets on form-stable polyethylene glycol/polymethyl methacrylate composite phase change materials

International Nuclear Information System (INIS)

Zhang, Lei; Zhu, Jiaoqun; Zhou, Weibing; Wang, Jun; Wang, Yan

2012-01-01

Graphite nanoplatelets (GnPs), obtained by sonicating the expanded graphite, were employed to simultaneously enhance the thermal (k) and electrical (σ) conductivity of organic form-stable phase change materials (FSPCMs). Using the method of in situ polymerization upon ultrasonic irradiation, GnPs serving as the conductive fillers and polyethylene glycol (PEG) acting as the phase change material (PCM) were uniformly dispersed and embedded inside the network structure of polymethyl methacrylate (PMMA), which contributed to the well package and self-supporting properties of composite FSPCMs. X-ray diffraction and Fourier transform infrared spectroscopy results indicated that the GnPs were physically combined with PEG/PMMA matrix and did not participate in the polymerization. The GnPs additives were able to effectively enhance the k and σ of organic FSPCM. When the mass ratio of GnP was 8%, the k and σ of FSPCM changed up to 9 times and 8 orders of magnitude over that of PEG/PMMA matrix, respectively. The improvements in both k and σ were mainly attributed to the well dispersion and large aspect ratio of GnPs, which were endowed with benefit of forming conducting network in polymer matrix. It was also confirmed that all the prepared specimens possessed available thermal storage density and thermal stability. -- Highlights: ► GnPs were employed to simultaneously enhance the k and σ of organic FSPCMs. ► PEG/PMMA/GnPs composite FSPCMs were prepared by in situ polymerization method. ► The composite FSPCMs exhibited well package and self-supporting properties. ► GnPs additives effectively enhanced the k and σ of composite FSPCMs. ► All the composites possessed available thermal storage density and thermal stability.

Nucleolin forms a specific complex with a fragment of the viral (minus) strand of minute virus of mice DNA.

Science.gov (United States)

Barrijal, S; Perros, M; Gu, Z; Avalosse, B L; Belenguer, P; Amalric, F; Rommelaere, J

1992-01-01

Nucleolin, a major nucleolar protein, forms a specific complex with the genome (a single-stranded DNA molecule of minus polarity) of parvovirus MVMp in vitro. By means of South-western blotting experiments, we mapped the binding site to a 222-nucleotide motif within the non-structural transcription unit, referred to as NUBE (nucleolin-binding element). The specificity of the interaction was confirmed by competitive gel retardation assays. DNaseI and nuclease S1 probing showed that NUBE folds into a secondary structure, in agreement with a computer-assisted conformational prediction. The whole NUBE may be necessary for the interaction with nucleolin, as suggested by the failure of NUBE subfragments to bind the protein and by the nuclease footprinting experiments. The present work extends the previously reported ability of nucleolin to form a specific complex with ribosomal RNA, to a defined DNA substrate. Considering the tropism of MVMp DNA replication for host cell nucleoli, these data raise the possibility that nucleolin may contribute to the regulation of the parvoviral life-cycle. Images PMID:1408821

New developments in the use of stable activable tracers in environmental science

International Nuclear Information System (INIS)

Loveland, W.; Keasler, K.; Ghannam, L.; Borovik, A.

1980-01-01

Recent developments in the use of stable activable tracers (SATs) in environmental science are reported. (A stable activable tracer is a stable material injected into a system under study and whose concentration is measured by post-sampling activation analysis.) The activable nuclear parts of the tracers studied have been rare earth nuclides with short-lived activation products or Cu. To trace the fate of fluid-bound pollutants (and/or water masses) in marine waters, we have used anionic DTPA complexes of the rare earths. These tracers were shown to be stable (80 to 90% nondissociated) in extensive laboratory tests involving solutions of the tracer in estuarine water including large amounts of marine sediments. Results of a field study in which the flushing time and other hydrological characteristics of an estuarine marina were measured by simultaneously using a fluorescent dye and a SAT are presented. To trace the path of potentially toxic organic molecules, three stable activable tracers, dysprosium(III)-trisacetylacetonate DY(acac) 3 3H 2 O), dysprosium(III)-trisdibenzoylmethane (DY(dbm) 3 H 2 O and copper oxinate Cu (C 9 H 6 ON) 2 were synthesized. Their octanol/water partition coefficients and their solubility in water were measured and used to correlate the tracer species and its biological activity with that of known toxic materials. In a project to demonstrate the simple use of SATs to trace the origin of common insecticides and herbicides, seven common insecticides and herbicides were marked with anionic rare earth DTPA complexes and shown to be detectable at dilutions of 1 part in 10 12 . Two arsenical herbicides were chosen for further study and the tracer/herbicide ratio was shown to remain constant in samples of herbicide material collected on plant surfaces and runoff waters in the environment for long periods

Synthesis and biodistribution of a novel 99mTc nitrido dithiocarbamate complex containing aromatic group for cerebral imaging

International Nuclear Information System (INIS)

Zhang Junbo; Lin Xiao; Ren Jialei; Liu Jing; Wang Xuebin

2010-01-01

In the present study, the N-benzyl dithiocarbamate (BZDTC) was synthesized and radiolabeled with [ 99m TcN] 2+ intermediate to form the bis(N-benzyl dithiocarbamato) nitrido technetium-99m complex [ 99m TcN(BZDTC) 2 ]. The radiochemical purity of the complex was over 90% by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC). It was stable over 6 h at room temperature. The partition coefficient and electrophoresis results indicated that this complex was lipophilic and neutral. Biodistribution in mice showed that the complex accumulated in the brain with high uptake. The brain uptake (ID%/g) was 1.87, 1.21 and 0.85 and the brain/blood ratio was 0.75, 1.55 and 1.12 at 5, 30 and 60 min post-injection, respectively. These results suggest that this complex could be a potential brain perfusion imaging agent.

Use of an exchange method to estimate the association and dissociation rate constants of cadmium complexes formed with low-molecular-weight organic acids commonly exuded by plant roots.

Science.gov (United States)

Schneider, André; Nguyen, Christophe

2011-01-01

Organic acids released from plant roots can form complexes with cadmium (Cd) in the soil solution and influence metal bioavailability not only due to the nature and concentration of the complexes but also due to their lability. The lability of a complex influences its ability to buffer changes in the concentration of free ions (Cd); it depends on the association (, m mol s) and dissociation (, s) rate constants. A resin exchange method was used to estimate and (m mol s), which is the conditional estimate of depending on the calcium (Ca) concentration in solution. The constants were estimated for oxalate, citrate, and malate, three low-molecular-weight organic acids commonly exuded by plant roots and expected to strongly influence Cd uptake by plants. For all three organic acids, the and estimates were around 2.5 10 m mol s and 1.3 × 10 s, respectively. Based on the literature, these values indicate that the Cd- low-molecular-weight organic acids complexes formed between Cd and low-molecular-weight organic acids may be less labile than complexes formed with soil soluble organic matter but more labile than those formed with aminopolycarboxylic chelates. Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.

Spectroscopic characterization of the oxyferrous complex of prostacyclin synthase in solution and in trapped sol–gel matrix

Science.gov (United States)

Yeh, Hui-Chun; Hsu, Pei-Yung; Tsai, Ah-Lim; Wang, Lee-Ho

2010-01-01

Prostacyclin synthase (PGIS) is a member of the cytochrome P450 family in which the oxyferrous complexes are generally labile in the absence of substrate. At 4 °C, the on-rate constants and off-rate constants of oxygen binding to PGIS in solution are 5.9 × 105 m−1 ·s−1 and 29 s−1, respectively. The oxyferrous complex decays to a ferric form at a rate of 12 s−1. We report, for the first time, a stable oxyferrous complex of PGIS in a transparent sol–gel monolith. The encapsulated ferric PGIS retained the same spectroscopic features as in solution. The binding capabilities of the encapsulated PGIS were demonstrated by spectral changes upon the addition of O-based, N-based and C-based ligands. The peroxidase activity of PGIS in sol–gel was three orders of magnitude slower than that in solution owing to the restricted diffusion of the substrate in sol–gel. The oxyferrous complex in sol–gel was observable for 24 h at room temperature and displayed a much red-shifted Soret peak. Stabilization of the ferrous–carbon monoxide complex in sol–gel was observed as an enrichment of the 450-nm species over the 420-nm species. This result suggests that the sol–gel method may be applied to other P450s to generate a stable intermediate in the di-oxygen activation. PMID:18397321

Modeling hemoglobin at optical frequency using the unconditionally stable fundamental ADI-FDTD method.

Science.gov (United States)

Heh, Ding Yu; Tan, Eng Leong

2011-04-12

This paper presents the modeling of hemoglobin at optical frequency (250 nm - 1000 nm) using the unconditionally stable fundamental alternating-direction-implicit finite-difference time-domain (FADI-FDTD) method. An accurate model based on complex conjugate pole-residue pairs is proposed to model the complex permittivity of hemoglobin at optical frequency. Two hemoglobin concentrations at 15 g/dL and 33 g/dL are considered. The model is then incorporated into the FADI-FDTD method for solving electromagnetic problems involving interaction of light with hemoglobin. The computation of transmission and reflection coefficients of a half space hemoglobin medium using the FADI-FDTD validates the accuracy of our model and method. The specific absorption rate (SAR) distribution of human capillary at optical frequency is also shown. While maintaining accuracy, the unconditionally stable FADI-FDTD method exhibits high efficiency in modeling hemoglobin.

Waste forms for plutonium disposition

International Nuclear Information System (INIS)

Johnson, S.G.; O'Holleran, T.P.; Frank, S.M.; Meyer, M.K.; Hanson, M.; Staples, B.A.; Knecht, D.A.; Kong, P.C.

1997-01-01

The field of plutonium disposition is varied and of much importance, since the Department of Energy has decided on the hybrid option for disposing of the weapons materials. This consists of either placing the Pu into mixed oxide fuel for reactors or placing the material into a stable waste form such as glass. The waste form used for Pu disposition should exhibit certain qualities: (1) provide for a suitable deterrent to guard against proliferation; (2) be of minimal volume, i.e., maximize the loading; and (3) be reasonably durable under repository-like conditions. This paper will discuss several Pu waste forms that display promising characteristics

Nanotechnology as an experiment in democracy: how do citizens form opinions about technology and policy?

International Nuclear Information System (INIS)

Hornig Priest, Susanna; Greenhalgh, Ted

2011-01-01

This article analyzes nanotechnology as an experiment in democratic deliberation, one that seems motivated both by a desire to improve deliberative democracy and to protect the technology from undue public interference. However, rather than involving amplified (overstated) risks, nanotechnology appears to involve attenuated (understated) risks. Results from a 3-year panel study are presented to illustrate the ways in which citizens form opinions about nanotechnology, supporting the assertion that public opinion about complex technology can be both reasonable and stable. Nevertheless, the authors also voice concern that, in the absence of public pressure, risk regulation may not evolve as swiftly as it should to protect both society and industry.

Soluble and stable zethrenebis(dicarboximide) and its quinone

KAUST Repository

Sun, Zhe

2010-10-15

Soluble and stable zethrenebis(dicarboximide) (1) was synthesized by an in situ Stille cross coupling/transannular cyclization reaction. 1 showed largely improved photostability and solubility compared with the very unstable zethrene and it also exhibited far-red absorption and emission with high photoluminescence quantum yield. Bromination of 1 with NBS/DMF gave its quinone form 2 via an unusual pathway. © 2010 American Chemical Society.

Current Challenges in Understanding and Forecasting Stable Boundary Layers over Land and Ice

Directory of Open Access Journals (Sweden)

Gert-Jan eSteeneveld

2014-10-01

Full Text Available Understanding and prediction of the stable atmospheric boundary layer is challenging. Many physical processes come into play in the stable boundary layer, i.e. turbulence, radiation, land surface coupling and heterogeneity, orographic turbulent and gravity wave drag. The development of robust stable boundary-layer parameterizations for weather and climate models is difficult because of the multiplicity of processes and their complex interactions. As a result, these models suffer from biases in key variables, such as the 2-m temperature, boundary-layer depth and wind speed. This short paper briefly summarizes the state-of-the-art of stable boundary layer research, and highlights physical processes that received only limited attention so far, in particular orographically-induced gravity wave drag, longwave radiation divergence, and the land-atmosphere coupling over a snow-covered surface. Finally, a conceptual framework with relevant processes and particularly their interactions is proposed.

[Evaluation of the clinical efficacy of a new composition of tizol with triamcinolon in complex treatment of patients with erosive ulcerous form of lichen planus of the oral mucosa].

Science.gov (United States)

Ron', G I; Akmalova, G M; Emel'yanova, I V

2015-01-01

The most significant of the primary stages of complex therapy of oral lichen planus (OLP), among causal and pathogenetic therapy is a local conservative treatment. The aim of the study was to evaluate the clinical efficacy of the local use of the new compositions TIZOL with triamcinolon in complex therapy of erosive-ulcerous forms OLP oral mucosa. The study was performed with 47 patients with lichen planus in age from 24 to 70 years with erosive-ulcerous form OLP whose diagnosis was confirmed histologically. The first group included 25 patients in the complex treatment of locally applied composition TIZOL with triamcinolon. The second group of 22 people, who in the complex treatment applied locally 0.5% prednisone ointment. The high efficiency of topical TIZOL with a highly topical steroid in the complex therapy of erosive-ulcerous forms OLP, which was confirmed by the positive clinical dynamics in all patients (100%) and high self-esteem of patients (84% positive ratings), reduced life complete epithelialization of erosions.

Preconcentration of metallic elements by complexation with ammonium pyrrolidine dithiocarbamate (APDC) for atomic absorption analysis

International Nuclear Information System (INIS)

Santos Coelho, Ricardo dos; Dantas, Elizabeth S.K.

1997-01-01

Ammonium pyrrolidine dithiocarbamate (APDC) forms stable chelates with many metals being therefore, used in systems of preconcentration for determination of heavy metals in water. In this work, the metals were complexed with APDC and extracted with methyl isobutyl ketone (MIBK). The results showed that the studied metals (Co, Cu, Fe, Ni, Pb, Cr and Cd), in the range of 2 to 5 μg, in 100 ml of sample, were quantitatively extracted in only one stage using 10 ml of MIBK and 5 ml of 4% APDC. The pH must be between 4 and 5. The complexes stability was also studied. The proposed method can be applied to pre concentrate heavy metals in natural waters. (author). 4 refs., 1 fig., 3 tabs

Properties of form-stable paraffin/silicon dioxide/expanded graphite phase change composites prepared by sol–gel method

International Nuclear Information System (INIS)

Li, Min; Wu, Zhishen; Tan, Jinmiao

2012-01-01

Highlights: ► Paraffin/SiO 2 /EG composite PCM was prepared with sol–gel method. ► The thermal conductivity of SiO 2 /paraffin/EG is 94.7% higher than paraffin. ► The latent heat of paraffin/SiO 2 /EG composite is 104.4 J/g. -- Abstract: A form-stable paraffin/silicon dioxide (SiO 2 )/expanded graphite (EG) composite phase change material (PCM) was prepared by sol–gel method. Silica gel acts as the supporting material and EG is used to increase the thermal conductivity. The mass fractions of silicon oxide and graphite are 20.8% and 7.2%, respectively. The composite PCM was characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transformation infrared spectroscopy (FTIR) method. Thermal properties and thermal stability of the composite PCM were studied using differential scanning calorimetry (DSC). The result shows that paraffin was well dispersed in the network of silica gel and there is no chemical reaction between them. The phase change temperature of the paraffin/SiO 2 composite and the paraffin/SiO 2 /EG composite are 27.53 °C and 27.72 °C, respectively. The latent heat of the paraffin/SiO 2 composite and the paraffin/SiO 2 /EG composite are 112.8 J/g and 104.4 J/g, respectively. The thermal conductivity of the SiO 2 /paraffin composite and the SiO 2 /paraffin/EG composite are 28.2% and 94.7% higher than that of paraffin.

High stability and biological activity of the copper(II) complexes of alloferon 1 analogues containing tryptophan.

Science.gov (United States)

Kadej, Agnieszka; Kuczer, Mariola; Czarniewska, Elżbieta; Urbański, Arkadiusz; Rosiński, Grzegorz; Kowalik-Jankowska, Teresa

2016-10-01

Copper(II) complex formation processes between the alloferon 1 (Allo1) (HGVSGHGQHGVHG) analogues where the tryptophan residue is introducing in the place His residue H1W, H6W, H9W and H12W have been studied by potentiometric, UV-visible, CD and EPR spectroscopic, and MS methods. For all analogues of alloferon 1 complex speciation have been obtained for a 1:1 metal-to-ligand molar ratio and 2:1 of H1W because of precipitation at higher (2:1, 3:1 and 4:1) ratios. At physiological pH7.4 and a 1:1 metal-to-ligand molar ratio the tryptophan analogues of alloferon 1 form the CuH -1 L and/or CuH -2 L complexes with the 4N binding mode. The introduction of tryptophan in place of histidine residues changes the distribution diagram of the complexes formed with the change of pH and their stability constants compared to the respective substituted alanine analogues of alloferon 1. The CuH -1 L, CuH -2 L and CuH -3 L complexes of the tryptophan analogues are more stable from 1 to 5 log units in comparison to those of the alanine analogues. This stabilization of the complexes may result from cation(Cu(II))-π and indole/imidazole ring interactions. The induction of apoptosis in vivo, in Tenebrio molitor cells by the ligands and their copper(II) complexes at pH7.4 was studied. The biological results show that copper(II) ions in vivo did not cause any apparent apoptotic features. The most active were the H12W peptide and Cu(II)-H12W complex formed at pH7.4. Copyright © 2016 Elsevier Inc. All rights reserved.

New stable phase in binary Fe-Nd

International Nuclear Information System (INIS)

Schneider, G.; Landgraf, F.J.G.; Villas-Boas, V.; Bezerra, G.H.; Missell, F.P.; Ray, A.E.

1992-01-01

An investigation of binary Fe-Nd alloys revealed the existence of an oxygen-free, stable Fe-rich phase A 2 , formed peritecticly in the range 750-800 deg C. EPMA shows this phase to contain 22.8 atomic percent Nd. This ferromagnetic phase has T c = 230 de C, but is magnetically soft. The X-ray diffraction pattern can be indexed using a hexagonal cell with a = 2.021 nm. and c = 1.235 nm. (author)

Polymer compositions, polymer films and methods and precursors for forming same

Science.gov (United States)

Klaehn, John R; Peterson, Eric S; Orme, Christopher J

2013-09-24

Stable, high performance polymer compositions including polybenzimidazole (PBI) and a melamine-formaldehyde polymer, such as methylated, poly(melamine-co-formaldehyde), for forming structures such as films, fibers and bulky structures. The polymer compositions may be formed by combining polybenzimidazole with the melamine-formaldehyde polymer to form a precursor. The polybenzimidazole may be reacted and/or intertwined with the melamine-formaldehyde polymer to form the polymer composition. For example, a stable, free-standing film having a thickness of, for example, between about 5 .mu.m and about 30 .mu.m may be formed from the polymer composition. Such films may be used as gas separation membranes and may be submerged into water for extended periods without crazing and cracking. The polymer composition may also be used as a coating on substrates, such as metal and ceramics, or may be used for spinning fibers. Precursors for forming such polymer compositions are also disclosed.

Phosphorescent Organic Light Emitting Diodes Implementing Platinum Complexes

Science.gov (United States)

Ecton, Jeremy Exton

Organic light emitting diodes (OLEDs) are a promising approach for display and solid state lighting applications. However, further work is needed in establishing the availability of efficient and stable materials for OLEDs with high external quantum efficiency's (EQE) and high operational lifetimes. Recently, significant improvements in the internal quantum efficiency or ratio of generated photons to injected electrons have been achieved with the advent of phosphorescent complexes with the ability to harvest both singlet and triplet excitons. Since then, a variety of phosphorescent complexes containing heavy metal centers including Os, Ni, Ir, Pd, and Pt have been developed. Thus far, the majority of the work in the field has focused on iridium based complexes. Platinum based complexes, however, have received considerably less attention despite demonstrating efficiency's equal to or better than their iridium analogs. In this study, a series of OLEDs implementing newly developed platinum based complexes were demonstrated with efficiency's or operational lifetimes equal to or better than their iridium analogs for select cases. In addition to demonstrating excellent device performance in OLEDs, platinum based complexes exhibit unique photophysical properties including the ability to form excimer emission capable of generating broad white light emission from a single emitter and the ability to form narrow band emission from a rigid, tetradentate molecular structure for select cases. These unique photophysical properties were exploited and their optical and electrical properties in a device setting were elucidated. Utilizing the unique properties of a tridentate Pt complex, Pt-16, a highly efficient white device employing a single emissive layer exhibited a peak EQE of over 20% and high color quality with a CRI of 80 and color coordinates CIE(x=0.33, y=0.33). Furthermore, by employing a rigid, tetradentate platinum complex, PtN1N, with a narrow band emission into a

The E. coli monothiol glutaredoxin GrxD forms homodimeric and heterodimeric FeS cluster containing complexes.

Science.gov (United States)

Yeung, N; Gold, B; Liu, N L; Prathapam, R; Sterling, H J; Willams, E R; Butland, G

2011-10-18

Monothiol glutaredoxins (mono-Grx) represent a highly evolutionarily conserved class of proteins present in organisms ranging from prokaryotes to humans. Mono-Grxs have been implicated in iron sulfur (FeS) cluster biosynthesis as potential scaffold proteins and in iron homeostasis via an FeS-containing complex with Fra2p (homologue of E. coli BolA) in yeast and are linked to signal transduction in mammalian systems. However, the function of the mono-Grx in prokaryotes and the nature of an interaction with BolA-like proteins have not been established. Recent genome-wide screens for E. coli genetic interactions reported the synthetic lethality (combination of mutations leading to cell death; mutation of only one of these genes does not) of a grxD mutation when combined with strains defective in FeS cluster biosynthesis (isc operon) functions [Butland, G., et al. (2008) Nature Methods 5, 789-795]. These data connected the only E. coli mono-Grx, GrxD to a potential role in FeS cluster biosynthesis. We investigated GrxD to uncover the molecular basis of this synthetic lethality and observed that GrxD can form FeS-bound homodimeric and BolA containing heterodimeric complexes. These complexes display substantially different spectroscopic and functional properties, including the ability to act as scaffold proteins for intact FeS cluster transfer to the model [2Fe-2S] acceptor protein E. coli apo-ferredoxin (Fdx), with the homodimer being significantly more efficient. In this work, we functionally dissect the potential cellular roles of GrxD as a component of both homodimeric and heterodimeric complexes to ultimately uncover if either of these complexes performs functions linked to FeS cluster biosynthesis. © 2011 American Chemical Society

Entropy-based generating Markov partitions for complex systems

Science.gov (United States)

Rubido, Nicolás; Grebogi, Celso; Baptista, Murilo S.

2018-03-01

Finding the correct encoding for a generic dynamical system's trajectory is a complicated task: the symbolic sequence needs to preserve the invariant properties from the system's trajectory. In theory, the solution to this problem is found when a Generating Markov Partition (GMP) is obtained, which is only defined once the unstable and stable manifolds are known with infinite precision and for all times. However, these manifolds usually form highly convoluted Euclidean sets, are a priori unknown, and, as it happens in any real-world experiment, measurements are made with finite resolution and over a finite time-span. The task gets even more complicated if the system is a network composed of interacting dynamical units, namely, a high-dimensional complex system. Here, we tackle this task and solve it by defining a method to approximately construct GMPs for any complex system's finite-resolution and finite-time trajectory. We critically test our method on networks of coupled maps, encoding their trajectories into symbolic sequences. We show that these sequences are optimal because they minimise the information loss and also any spurious information added. Consequently, our method allows us to approximately calculate the invariant probability measures of complex systems from the observed data. Thus, we can efficiently define complexity measures that are applicable to a wide range of complex phenomena, such as the characterisation of brain activity from electroencephalogram signals measured at different brain regions or the characterisation of climate variability from temperature anomalies measured at different Earth regions.

Mechanical Properties of Stable Glasses Using Nanoindentation

Science.gov (United States)

Wolf, Sarah; Liu, Tianyi; Jiang, Yijie; Ablajan, Keyume; Zhang, Yue; Walsh, Patrick; Turner, Kevin; Fakhraai, Zahra

Glasses with enhanced stability over ordinary, liquid quenched glasses have been formed via the process of Physical Vapor Deposition (PVD) by using a sufficiently slow deposition rate and a substrate temperature slightly below the glass transition temperature. These stable glasses have been shown to exhibit higher density, lower enthalpy, and better kinetic stability over ordinary glass, and are typically optically birefringent, due to packing and orientational anisotropy. Given these exceptional properties, it is of interest to further investigate how the properties of stable glasses compare to those of ordinary glass. In particular, the mechanical properties of stable glasses remain relatively under-investigated. While the speed of sound and elastic moduli have been shown to increase with increased stability, little is known about their hardness and fracture toughness compared to ordinary glasses. In this study, glasses of 9-(3,5-di(naphthalen-1-yl)phenyl)anthracene were deposited at varying temperatures relative to their glass transition temperature, and their mechanical properties measured by nanoindentation. Hardness and elastic modulus of the glasses were compared across substrate temperatures. After indentation, the topography of these films were studied using Atomic Force Microscopy (AFM) in order to further compare the relationship between thermodynamic and kinetic stability and mechanical failure. Z.F. and P.W. acknowledge funding from NSF(DMREF-1628407).

Convection in complex shaped vessel; Convection dans des enceintes de forme complexe

Energy Technology Data Exchange (ETDEWEB)

NONE

2000-07-01

The 8 november 2000, the SFT (Societe Francaise de Thermique) organized a technical day on the convection in complex shaped vessels. Nine papers have been presented in the domains of the heat transfers, the natural convection, the fluid distribution, the thermosyphon effect, the steam flow in a sterilization cycle and the transformers cooling. Eight papers are analyzed in ETDE and one paper dealing with the natural convection in spent fuels depository is analyzed in INIS. (A.L.B.)

Entropy Stable Summation-by-Parts Formulations for Compressible Computational Fluid Dynamics

KAUST Repository

Carpenter, M.H.

2016-11-09

A systematic approach based on a diagonal-norm summation-by-parts (SBP) framework is presented for implementing entropy stable (SS) formulations of any order for the compressible Navier–Stokes equations (NSE). These SS formulations discretely conserve mass, momentum, energy and satisfy a mathematical entropy equality for smooth problems. They are also valid for discontinuous flows provided sufficient dissipation is added at shocks and discontinuities to satisfy an entropy inequality. Admissible SBP operators include all centred diagonal-norm finite-difference (FD) operators and Legendre spectral collocation-finite element methods (LSC-FEM). Entropy stable multiblock FD and FEM operators follows immediately via nonlinear coupling operators that ensure conservation, accuracy and preserve the interior entropy estimates. Nonlinearly stable solid wall boundary conditions are also available. Existing SBP operators that lack a stability proof (e.g. weighted essentially nonoscillatory) may be combined with an entropy stable operator using a comparison technique to guarantee nonlinear stability of the pair. All capabilities extend naturally to a curvilinear form of the NSE provided that the coordinate mappings satisfy a geometric conservation law constraint. Examples are presented that demonstrate the robustness of current state-of-the-art entropy stable SBP formulations.

Guest-Host Complex Formed between Ascorbic Acid and β-Cyclodextrin Immobilized on the Surface of an Electrode

Directory of Open Access Journals (Sweden)

María Teresa Ramírez-Silva

2014-05-01

Full Text Available This work deals with the formation of supramolecular complexes between ascorbic acid (AA, the guest, and β-cyclodextrin (β-CD, the host, that was first potentiodynamically immobilized on the surface of a carbon paste electrode (CPE throughout the formation of a β-CD-based conducting polymer (poly-β-CD. With the bare CPE and the β-CD-modified CPE, an electrochemical study was performed to understand the effect of such surface modification on the electrochemical response of the AA. From this study it was shown that on the modified-CPE, the AA was surface-immobilized through formation of an inclusion complex with β-CD, which provoked the adsorption of AA in such a way that this stage became the limiting step for the electrochemical oxidation of AA. Moreover, from the analysis of the experimental voltammetric plots recorded during AA oxidation on the CPE/poly-β-CD electrode surfaces, the Gibbs’ standard free energy of the inclusion complex formed by the oxidation product of AA and β-CD has been determined for the first time, ∆G0inclus = −36.4 kJ/mol.

Unsymmetrical dizinc complexes as models for the active sites of phosphohydrolases.

Science.gov (United States)

Jarenmark, Martin; Csapó, Edit; Singh, Jyoti; Wöckel, Simone; Farkas, Etelka; Meyer, Franc; Haukka, Matti; Nordlander, Ebbe

2010-09-21

The unsymmetrical dinucleating ligand 2-(N-isopropyl-N-((2-pyridyl)methyl)aminomethyl)-6-(N-(carboxylmethyl)-N-((2-pyridyl)methyl)aminomethyl)-4-methylphenol (IPCPMP or L) has been synthesized to model the active site environment of dinuclear metallohydrolases. It has been isolated as the hexafluorophosphate salt H(4)IPCPMP(PF(6))(2) x 2 H(2)O (H(4)L), which has been structurally characterized, and has been used to form two different Zn(II) complexes, [{Zn(2)(IPCPMP)(OAc)}(2)][PF(6)](2) (2) and [{Zn(2)(IPCPMP)(Piv)}(2)][PF(6)](2) (3) (OAc = acetate; Piv = pivalate). The crystal structures of and show that they consist of tetranuclear complexes with very similar structures. Infrared spectroscopy and mass spectrometry indicate that the tetranuclear complexes dissociate into dinuclear complexes in solution. Potentiometric studies of the Zn(II):IPCPMP system in aqueous solution reveal that a mononuclear complex is surprisingly stable at low pH, even at a 2:1 Zn(II):L ratio, but a dinuclear complex dominates at high pH and transforms into a dihydroxido complex by a cooperative deprotonation of two, probably terminally coordinated, water molecules. A kinetic investigation indicates that one of these hydroxides is the active nucleophile in the hydrolysis of bis(2,4-dinitrophenyl)phosphate (BDNPP) enhanced by complex 2, and mechanistic proposals are presented for this reaction as well as the previously reported transesterification of 2-hydroxypropyl p-nitrophenyl phosphate (HPNP) promoted by Zn(II) complexes of IPCPMP.

Application of stable crack growth in fracture assessment of defects in ductile materials

International Nuclear Information System (INIS)

Dillstroem, Peter

2009-06-01

This report goes through the use of methods/standards, which consider stable (J-controlled) crack growth. We have demonstrated the following: - ASME XI, App. C, App. H, which deals with analysis of stainless steel and ferritic piping, take account of stable growth. In App. C, this corresponds to the inclusion of stable growth up to Δa ∼ 10 mm. - R6-method, BS 7910:1999 and ASME XI, Code Case N-494, contains an established formalism to take account of stable growth. A prerequisite is that you have access to relevant and authentic material data in the form of fracture resistance K k /J k and J r curves. - All of the above methods/standards are applicable in the nuclear context. We reported also that required to produce relevant and valid data (fracture resistance K k /J k and J r curves) to be used for the analysis of stable growth. This report does not specify how much stable crack that can be counted at a Safety Assessment

Economic interpretation of sustainable development of the flax complex

Directory of Open Access Journals (Sweden)

Oleg Ivanovich Botkin

2012-09-01

Full Text Available This paper reviews the definition of the notions “stability” and “stable development”, and analyzes the factors influencing the development stability. We suggest the definition of the flax complex stable development and its assessment. We also examine the factors causing the flax complex functioning instability. An integral index was proposed to determine the stability of flax complex; this index takes into account the rate of growth (or decline of major products manufacturing, commodities, profits from product sales, accounts receivable and accounts payable, investments into fixed capital, labor productivity, coefficient of manufacturing capacity utilization and updating of the basic funds. The paper deals with the problems of its development and modern state of flax sub-complex of agroindustrial complex, as well as with the matters of disproportions between the complex’s branches. It covers the causes of tolling schemes of flax processing businesses work and therole of thestatein native market of flax products formation. The necessity of industry diversification and innovation development is substantiated.

The role of proteolytic processing and the stable signal peptide in expression of the Old World arenavirus envelope glycoprotein ectodomain

International Nuclear Information System (INIS)

Burri, Dominique J.; Pasquato, Antonella; Ramos da Palma, Joel; Igonet, Sebastien; Oldstone, Michael B.A.; Kunz, Stefan

2013-01-01

Maturation of the arenavirus GP precursor (GPC) involves proteolytic processing by cellular signal peptidase and the proprotein convertase subtilisin kexin isozyme 1 (SKI-1)/site 1 protease (S1P), yielding a tripartite complex comprised of a stable signal peptide (SSP), the receptor-binding GP1, and the fusion-active transmembrane GP2. Here we investigated the roles of SKI-1/S1P processing and SSP in the biosynthesis of the recombinant GP ectodomains of lymphocytic choriomeningitis virus (LCMV) and Lassa virus (LASV). When expressed in mammalian cells, the LCMV and LASV GP ectodomains underwent processing by SKI-1/S1P, followed by dissociation of GP1 from GP2. The GP2 ectodomain spontaneously formed trimers as revealed by chemical cross-linking. The endogenous SSP, known to be crucial for maturation and transport of full-length arenavirus GPC was dispensable for processing and secretion of the soluble GP ectodomain, suggesting a specific role of SSP in the stable prefusion conformation and transport of full-length GPC.

The role of proteolytic processing and the stable signal peptide in expression of the Old World arenavirus envelope glycoprotein ectodomain

Energy Technology Data Exchange (ETDEWEB)

Burri, Dominique J.; Pasquato, Antonella; Ramos da Palma, Joel [Institute of Microbiology, University Hospital Center and University of Lausanne, Lausanne CH-1011 (Switzerland); Igonet, Sebastien; Oldstone, Michael B.A. [Department of Immunology and Microbial Science, The Scripps Research Institute, La Jolla, CA 92037 (United States); Kunz, Stefan, E-mail: Stefan.Kunz@chuv.ch [Institute of Microbiology, University Hospital Center and University of Lausanne, Lausanne CH-1011 (Switzerland)

2013-02-05

Maturation of the arenavirus GP precursor (GPC) involves proteolytic processing by cellular signal peptidase and the proprotein convertase subtilisin kexin isozyme 1 (SKI-1)/site 1 protease (S1P), yielding a tripartite complex comprised of a stable signal peptide (SSP), the receptor-binding GP1, and the fusion-active transmembrane GP2. Here we investigated the roles of SKI-1/S1P processing and SSP in the biosynthesis of the recombinant GP ectodomains of lymphocytic choriomeningitis virus (LCMV) and Lassa virus (LASV). When expressed in mammalian cells, the LCMV and LASV GP ectodomains underwent processing by SKI-1/S1P, followed by dissociation of GP1 from GP2. The GP2 ectodomain spontaneously formed trimers as revealed by chemical cross-linking. The endogenous SSP, known to be crucial for maturation and transport of full-length arenavirus GPC was dispensable for processing and secretion of the soluble GP ectodomain, suggesting a specific role of SSP in the stable prefusion conformation and transport of full-length GPC.

Interaction of plutonium with complexing substances in soils and natural waters

International Nuclear Information System (INIS)

Bondietti, E.A.; Reynolds, S.A.; Shanks, M.H.

1976-01-01

The reactions of Pu with selected organic substances found in the environment have been studied to evaluate the valence and metalcomplex behaviour of Pu. Hexavalent Pu (and by inference pentavalent Pu) was unstable in the presence of fulvic acid, polygalacturonic acid, and alginic acid. Citrate-Pu(VI) complexes, however, were relatively more stable. Plutonium (IV) was the most stable valence upon interaction with these organics. Further reduction of Pu(IV) to Pu(III) occurred by fulvic and humic acids. The reduction, under aerobic conditions, does not appear to occur above pH 3.1. The reduction mechanisms is probably similar to the Fe(III) reduction previously documented for phenolic humic substances. Data are presented that demonstrate that Pu is at least partially associated with humic materials in ORNL soil contaminated 30 years ago with trace levels of Pu. Desorption studies using solid exchange resins also showed that, while a cation exchange resin did not desorb Pu from soil after 14 weeks equilibration, chelating resin effected Pu desorption. The desorption rate was not constant, suggesting differential Pu forms. While the resin-extractable Pu was believed to originate from solid-phase organic complexes, over 80% of the Pu in this soil was not readily resin-desorbable. This indicates that more inert soil-Pu reaction products effectively immobilize soil Pu. Some of these associations also appear to be organic. (author)

Statistical complexity without explicit reference to underlying probabilities

Science.gov (United States)

Pennini, F.; Plastino, A.

2018-06-01

We show that extremely simple systems of a not too large number of particles can be simultaneously thermally stable and complex. To such an end, we extend the statistical complexity's notion to simple configurations of non-interacting particles, without appeal to probabilities, and discuss configurational properties.

Complex emergent dynamics of anisotropic swarms: Convergence vs oscillation

International Nuclear Information System (INIS)

Chu Tianguang; Wang Long; Chen Tongwen; Mu Shumei

2006-01-01

This paper considers an anisotropic swarm model with a simple attraction and repulsion function. It is shown that the members of a reciprocal swarm will aggregate and eventually form a cohesive cluster of finite size around the swarm center. Moreover, the swarm system is also completely stable, i.e., every solution converges to the set of equilibrium points of the system. These results are also valid for a class of non-reciprocal swarms under the detailed balance condition on coupling weights. For general non-reciprocal swarms, numerical simulations are worked out to demonstrate more complex oscillatory motions in the systems. The study provides further insight into the effect of the interaction pattern on the collective behavior of a swarm system

Mixing of fluids in hydrothermal ore-forming (Sn,W) systems: stable isotope and rare earth elements data

Science.gov (United States)

Sushchevskaya, T. M.; Popova, J. A.; Velivetskaya, T. A.; Ignatiev, A. V.; Matveeva, S. S.; Limantseva, O. A.

2012-04-01

Experimental and physico-chemical modeling data witness to important role of mixing of different type of fluids during tin and tungsten ore formation in hydrothermal systems. Mixing of magmatogeneous fluids, exsolved from granite melts, with exogenic, initially meteoric waters in hydrothermal ore-forming systems may change chemical composition of ore-forming fluid, causing cassiterite and/or wolframite precipitation (Heinrich, 1990; Sushchevskaya, Ryzhenko, 2002). We studied the process of genetically different fluids mixing for two economic Sn-W deposits, situated in the Iultin ore region (North-East of Russia, Chukotka Penninsula). The Iultin and Svetloe deposits are located in the apical parts of close situated leucogranite stocks, formed at the final stage of the Iultin complex emplacement. Both deposits are composed of a series of quartz veins among the flyschoid rocks (T 1-2), cut by the dikes (K1) of lamprophyre, granodiorite porphyre and alpite. The veins of the deposits are dominated by the productive quartz-wolframite-cassiterite-arsenopyrite-muscovite mineral assemblage. Topaz, beryl, fluorite, and albite occur sporadically. The later sulfide (loellingite-stannite-chalcopyrite) and quartz-fluorite-calcite assemblages show insignificant development. The preore quartz veinlets in host hornfels contain disseminated iron sulfides, chalcopyrite, muscovite. Isotopic (H, O, Ar) study of minerals, supplemented by oxygen isotope data of host granites and metamorphic rocks gave us possibility to conclude, that at the Iultin and the Svetloye deposits fluid mixing was fixed on the early stages of deposit formation and could be regarded as probable cause of metal (W, Sn) precipitation. During postore time the intensive involvement of isotopically light exogenic waters have changed: a) the initial character of oxygen isotope zonality; b) the initial hydrogen isotope composition of muscovites, up to meteoric calculated values for productive fluid (while the δ18O

Adaptive control for a class of nonlinear complex dynamical systems with uncertain complex parameters and perturbations.

Directory of Open Access Journals (Sweden)

Jian Liu

Full Text Available In this paper, adaptive control is extended from real space to complex space, resulting in a new control scheme for a class of n-dimensional time-dependent strict-feedback complex-variable chaotic (hyperchaotic systems (CVCSs in the presence of uncertain complex parameters and perturbations, which has not been previously reported in the literature. In detail, we have developed a unified framework for designing the adaptive complex scalar controller to ensure this type of CVCSs asymptotically stable and for selecting complex update laws to estimate unknown complex parameters. In particular, combining Lyapunov functions dependent on complex-valued vectors and back-stepping technique, sufficient criteria on stabilization of CVCSs are derived in the sense of Wirtinger calculus in complex space. Finally, numerical simulation is presented to validate our theoretical results.

Adaptive control for a class of nonlinear complex dynamical systems with uncertain complex parameters and perturbations.

Science.gov (United States)

Liu, Jian; Liu, Kexin; Liu, Shutang

2017-01-01

In this paper, adaptive control is extended from real space to complex space, resulting in a new control scheme for a class of n-dimensional time-dependent strict-feedback complex-variable chaotic (hyperchaotic) systems (CVCSs) in the presence of uncertain complex parameters and perturbations, which has not been previously reported in the literature. In detail, we have developed a unified framework for designing the adaptive complex scalar controller to ensure this type of CVCSs asymptotically stable and for selecting complex update laws to estimate unknown complex parameters. In particular, combining Lyapunov functions dependent on complex-valued vectors and back-stepping technique, sufficient criteria on stabilization of CVCSs are derived in the sense of Wirtinger calculus in complex space. Finally, numerical simulation is presented to validate our theoretical results.

Constant Electric and Magnetic Fields Effect on the Structuring and Thermomechanical and Thermophysical Properties of Nanocomposites Formed from Pectin-Cu(2+)-Polyethyleneimine Interpolyelectrolyte-Metal Complexes.

Science.gov (United States)

Demchenko, V; Shtompel', V; Riabov, S; Lysenkov, E

2015-12-01

Applying wide-angle X-ray scattering method, thermomechanical analysis, and differential scanning calorimetry, the structural organization and properties of nanocomposites formed by chemical reduction of Сu(2+) cations in the interpolyelectrolyte-metal complex (pectin-Cu(2+)-polyethyleneimine) under the influence of a constant magnetic and electric fields have been studied. It has been found that the chemical reduction of Cu(2+) cations in the interpolyelectrolyte-metal complex bulk under constant electric and magnetic fields leads to formation of nanocomposite consisting of interpolyelectrolyte complex, including pectin-polyethyleneimine and nanoparticles of the metal Cu phase, whereas nanocomposite with Cu/Cu2O nanoparticles is formed in original state (without any field). It was observed that, under constant field, nanocomposites obtained have higher structural glass-transition temperatures and thermal stability.

Solid State Pathways towards Molecular Complexity in Space

Science.gov (United States)

Linnartz, Harold; Bossa, Jean-Baptiste; Bouwman, Jordy; Cuppen, Herma M.; Cuylle, Steven H.; van Dishoeck, Ewine F.; Fayolle, Edith C.; Fedoseev, Gleb; Fuchs, Guido W.; Ioppolo, Sergio; Isokoski, Karoliina; Lamberts, Thanja; Öberg, Karin I.; Romanzin, Claire; Tenenbaum, Emily; Zhen, Junfeng

2011-12-01

It has been a long standing problem in astrochemistry to explain how molecules can form in a highly dilute environment such as the interstellar medium. In the last decennium more and more evidence has been found that the observed mix of small and complex, stable and highly transient species in space is the cumulative result of gas phase and solid state reactions as well as gas-grain interactions. Solid state reactions on icy dust grains are specifically found to play an important role in the formation of the more complex ``organic'' compounds. In order to investigate the underlying physical and chemical processes detailed laboratory based experiments are needed that simulate surface reactions triggered by processes as different as thermal heating, photon (UV) irradiation and particle (atom, cosmic ray, electron) bombardment of interstellar ice analogues. Here, some of the latest research performed in the Sackler Laboratory for Astrophysics in Leiden, the Netherlands is reviewed. The focus is on hydrogenation, i.e., H-atom addition reactions and vacuum ultraviolet irradiation of interstellar ice analogues at astronomically relevant temperatures. It is shown that solid state processes are crucial in the chemical evolution of the interstellar medium, providing pathways towards molecular complexity in space.

Preparation and properties of 1-tetradecanol/1,3:2,4-di-(3,4-dimethyl) benzylidene sorbitol gelatinous form-stable phase change materials

International Nuclear Information System (INIS)

Tian, Tuo; Song, Jian; Niu, Libo; Feng, Rongxiu

2013-01-01

Graphical abstract: The 1,3:2,4-di-(3,4-dimethyl) benzylidene sorbitol can self-assemble to form three-dimensional network and immobilized the 1-tetradecanol. As a result, the gel-to-sol transition temperature of the composite PCM increased and the 1-tetradecanol leakage decreased. Highlights: ► First used of 1,3:2,4-di-(3,4-dimethyl) benzylidene sorbitol in alcohol-based PCMs. ► A new method of doping with exfoliated graphite is presented. ► A possible mechanism for decreasing leakage has been proposed based on SEM results. ► The prepared composite PCMs showed a high-energy storage density. ► The addition of exfoliated graphite enhanced the thermal conductivity of the PCMs. - Abstract: A 1-tetradecanol (TD)/1,3:2,4-di-(3,4-dimethyl) benzylidene sorbitol (DMDBS) composite was prepared as a novel form-stable phase change material (PCM), and the properties of the composites such as the gel-to-sol transition temperature, the latent heat, the microstructure and the thermal storage performance were characterized. The composite was prepared by impregnating DMDBS into TD and the maximum feasible weight percentage of TD was determined to be 94.2 wt%. The gel-to-sol transition temperature of the composite PCM was 158.3–180.0 °C, which is well above the melting point of 1-tetradecanol. Differential scanning calorimeter (DSC) was used to determine the melting and freezing enthalpies of 1-tetradecanol in the composite PCM and the values are 218.5 and 215.3 J g −1 , respectively. Scanning electron microscopy (SEM) results showed that 1-tetradecanol dispersed in the three-dimensional network formed by DMDBS. The relationship between the amount of DMDBS additive and the leakage was also discussed. The thermal conductivity of the composite PCM was improved by doping with exfoliated graphite

Peroxy-Titanium Complex-based inks for low temperature compliant anatase thin films.

Science.gov (United States)

Shabanov, N S; Asvarov, A Sh; Chiolerio, A; Rabadanov, K Sh; Isaev, A B; Orudzhev, F F; Makhmudov, S Sh

2017-07-15

Stable highly crystalline titanium dioxide colloids are of paramount importance for the establishment of a solution-processable library of materials that could help in bringing the advantages of digital printing to the world of photocatalysis and solar energy conversion. Nano-sized titanium dioxide in the anatase phase was synthesized by means of hydrothermal methods and treated with hydrogen peroxide to form Peroxy-Titanium Complexes (PTCs). The influence of hydrogen peroxide on the structural, optical and rheological properties of titanium dioxide and its colloidal solutions were assessed and a practical demonstration of a low temperature compliant digitally printed anatase thin film given. Copyright © 2017 Elsevier Inc. All rights reserved.

Crystallization and preliminary X-ray analysis of the complexes between a Fab and two forms of human insulin-like growth factor II

International Nuclear Information System (INIS)

Newman, Janet; Cohen, Edward H.; Cosgrove, Leah; Kopacz, Kris; Dransfield, Daniel T.; Adams, Timothy E.; Peat, Thomas S.

2009-01-01

Complexes of both hIGF-II and hIGF-IIE with a Fab have been crystallized and investigated by X-ray analysis. Elevated expression of insulin-like growth factor II (IGF-II) is frequently observed in a variety of human malignancies, including breast, colon and liver cancer. As IGF-II can deliver a mitogenic signal through both the type 1 insulin-like growth factor receptor (IGF-IR) and an alternately spliced form of the insulin receptor (IR-A), neutralizing the biological activity of this growth factor directly is an attractive therapeutic option. One method of doing this would be to find antibodies that bind tightly and specifically to the peptide, which could be used as protein therapeutics to lower the peptide levels in vivo and/or to block the peptide from binding to the IGF-IR or IR-A. To address this, Fabs were selected from a phage-display library using a biotinylated precursor form of the growth factor known as IGF-IIE as a target. Fabs were isolated that were specific for the E-domain C-terminal extension and for mature IGF-II. Four Fabs selected from the library were produced, complexed with IGF-II and set up in crystallization trials. One of the Fab–IGF-II complexes (M64-F02–IGF-II) crystallized readily, yielding crystals that diffracted to 2.2 Å resolution and belonged to space group P2 1 2 1 2 1 , with unit-cell parameters a = 50.7, b = 106.9, c = 110.7 Å. There was one molecule of the complete complex in the asymmetric unit. The same Fab was also crystallized with a longer form of the growth factor, IGF-IIE. This complex crystallized in space group P2 1 2 1 2 1 , with unit-cell parameters a = 50.7, b = 107, c = 111.5 Å, and also diffracted X-rays to 2.2 Å resolution

Weak convergence to isotropic complex [Formula: see text] random measure.

Science.gov (United States)

Wang, Jun; Li, Yunmeng; Sang, Liheng

2017-01-01

In this paper, we prove that an isotropic complex symmetric α -stable random measure ([Formula: see text]) can be approximated by a complex process constructed by integrals based on the Poisson process with random intensity.

Bovine lactoferrin binds oleic acid to form an anti-tumor complex similar to HAMLET.

Science.gov (United States)

Fang, Bing; Zhang, Ming; Tian, Mai; Jiang, Lu; Guo, Hui Yuan; Ren, Fa Zheng

2014-04-04

α-Lactalbumin (α-LA) can bind oleic acid (OA) to form HAMLET-like complexes, which exhibited highly selective anti-tumor activity in vitro and in vivo. Considering the structural similarity to α-LA, we conjectured that lactoferrin (LF) could also bind OA to obtain a complex with anti-tumor activity. In this study, LF-OA was prepared and its activity and structural changes were compared with α-LA-OA. The anti-tumor activity was evaluated by methylene blue assay, while the apoptosis mechanism was analyzed using flow cytometry and Western blot. Structural changes of LF-OA were measured by fluorescence spectroscopy and circular dichroism. The interactions of OA with LF and α-LA were evaluated by isothermal titration calorimetry (ITC). LF-OA was obtained by heat-treatment at pH8.0 with LD50 of 4.88, 4.95 and 4.62μM for HepG2, HT29, and MCF-7 cells, respectively, all of which were 10 times higher than those of α-LA-OA. Similar to HAMLET, LF-OA induced apoptosis in tumor cells through both death receptor- and mitochondrial-mediated pathways. Exposure of tryptophan residues and the hydrophobic regions as well as the loss of tertiary structure were observed in LF-OA. Besides these similarities, LF showed different secondary structure changes when compared with α-LA, with a decrease of α-helix and β-turn and an increase of β-sheet and random coil. ITC results showed that there was a higher binding number of OA to LF than to α-LA, while both of the proteins interacted with OA through van der Waals forces and hydrogen bonds. This study provides a theoretical basis for further exploration of protein-OA complexes. Copyright © 2013 The Authors. Published by Elsevier B.V. All rights reserved.

Parkinson-dementia complex and development of a new stable isotope dilution assay for BMAA detection in tissue

International Nuclear Information System (INIS)

Snyder, Laura R.; Cruz-Aguado, Reyniel; Sadilek, Martin; Galasko, Douglas; Shaw, Christopher A.; Montine, Thomas J.

2009-01-01

β-Methylamino-L-alanine (BMAA) has been proposed as a global contributor to neurodegenerative diseases, including Parkinson-dementia complex (PDC) of Guam and Alzheimer's disease (AD). The literature on the effects of BMAA is conflicting with some but not all in vitro data supporting a neurotoxic action, and experimental animal data failing to replicate the pattern of neurodegeneration of these human diseases, even at very high exposures. Recently, BMAA has been reported in human brain from individuals afflicted with PDC or AD. Some of the BMAA in human tissue reportedly is freely extractable (free) while some is protein-associated and liberated by techniques that hydrolyze the peptide bond. The latter is especially intriguing since BMAA is a non-proteinogenic amino acid that has no known tRNA. We attempted to replicate these findings with techniques similar to those used by others; despite more than adequate sensitivity, we were unable to detect free BMAA. Recently, using a novel stable isotope dilution assay, we again were unable to detect free or protein-associated BMAA in human cerebrum. Here we review the development of our new assay for tissue detection of BMAA and show that we are able to detect free BMAA in liver but not cerebrum, nor do we detect any protein-associated BMAA in mice fed this amino acid. These studies demonstrate the importance of a sensitive and specific assay for tissue BMAA and seriously challenge the proposal that BMAA is accumulating in human brain.

Whirlin and PDZ domain-containing 7 (PDZD7) proteins are both required to form the quaternary protein complex associated with Usher syndrome type 2.

Science.gov (United States)

Chen, Qian; Zou, Junhuang; Shen, Zuolian; Zhang, Weiping; Yang, Jun

2014-12-26

Usher syndrome (USH) is the leading genetic cause of combined hearing and vision loss. Among the three USH clinical types, type 2 (USH2) occurs most commonly. USH2A, GPR98, and WHRN are three known causative genes of USH2, whereas PDZD7 is a modifier gene found in USH2 patients. The proteins encoded by these four USH genes have been proposed to form a multiprotein complex, the USH2 complex, due to interactions found among some of these proteins in vitro, their colocalization in vivo, and mutual dependence of some of these proteins for their normal in vivo localizations. However, evidence showing the formation of the USH2 complex is missing, and details on how this complex is formed remain elusive. Here, we systematically investigated interactions among the intracellular regions of the four USH proteins using colocalization, yeast two-hybrid, and pull-down assays. We show that multiple domains of the four USH proteins interact among one another. Importantly, both WHRN and PDZD7 are required for the complex formation with USH2A and GPR98. In this USH2 quaternary complex, WHRN prefers to bind to USH2A, whereas PDZD7 prefers to bind to GPR98. Interaction between WHRN and PDZD7 is the bridge between USH2A and GPR98. Additionally, the USH2 quaternary complex has a variable stoichiometry. These findings suggest that a non-obligate, short term, and dynamic USH2 quaternary protein complex may exist in vivo. Our work provides valuable insight into the physiological role of the USH2 complex in vivo and informs possible reconstruction of the USH2 complex for future therapy. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Theoretical study of the binding nature of glassy carbon with nickel(II) phthalocyanine complexes

International Nuclear Information System (INIS)

Cortez, Luis; Berrios, Cristhian; Yanez, Mauricio; Cardenas-Jiron, Gloria I.

2009-01-01

A theoretical study at the semiempirical RHF/PM3(tm) level (tm: transition metal) of the binding nature between a glassy carbon (GC) cluster and a nickel(II) complex (nickel(II) phthalocyanine NiPc, nickel(II) tetrasulphophthalocyanine NiTSPc) was performed. Three types of interactions for GC...NiPc (NiTSPc) were studied: (a) through an oxo (O) bridge, (b) through an hydroxo (OH) bridge, and (c) non-bridge. One layer (NiPc, NiTSPc) and two layers (NiPc...NiPc) of complex were considered. The binding energy calculated showed that in both cases NiPc and NiTSPc, the oxo structures are more stable than the hydroxo ones, and than the non-bridge systems. Charge analysis (NAO) predicted that GC gained more electrons in an oxo structure than in the analogues hydroxo. The theoretical results showed an agreement with the experimental data available, an oxo binding between GC and a nickel complex (NiPc, NiTSPc) in aqueous alkaline solutions is formed.

Theoretical study of the binding nature of glassy carbon with nickel(II) phthalocyanine complexes

Energy Technology Data Exchange (ETDEWEB)

Cortez, Luis [Laboratorio de Quimica Teorica, Facultad de Quimica y Biologia, Universidad de Santiago de Chile (USACH), Casilla 40, Correo 33, Santiago (Chile); Berrios, Cristhian [Laboratorio de Electrocatalisis, Facultad de Quimica y Biologia, Universidad de Santiago de Chile (USACH), Casilla 40, Correo 33, Santiago (Chile); Yanez, Mauricio [Laboratorio de Recursos Renovables, Centro de Biotecnologia, Universidad de Concepcion, Casilla-160 C, Concepcion (Chile); Cardenas-Jiron, Gloria I., E-mail: gloria.cardenas@usach.cl [Laboratorio de Quimica Teorica, Facultad de Quimica y Biologia, Universidad de Santiago de Chile (USACH), Casilla 40, Correo 33, Santiago (Chile)

2009-11-26

A theoretical study at the semiempirical RHF/PM3(tm) level (tm: transition metal) of the binding nature between a glassy carbon (GC) cluster and a nickel(II) complex (nickel(II) phthalocyanine NiPc, nickel(II) tetrasulphophthalocyanine NiTSPc) was performed. Three types of interactions for GC...NiPc (NiTSPc) were studied: (a) through an oxo (O) bridge, (b) through an hydroxo (OH) bridge, and (c) non-bridge. One layer (NiPc, NiTSPc) and two layers (NiPc...NiPc) of complex were considered. The binding energy calculated showed that in both cases NiPc and NiTSPc, the oxo structures are more stable than the hydroxo ones, and than the non-bridge systems. Charge analysis (NAO) predicted that GC gained more electrons in an oxo structure than in the analogues hydroxo. The theoretical results showed an agreement with the experimental data available, an oxo binding between GC and a nickel complex (NiPc, NiTSPc) in aqueous alkaline solutions is formed.

The FA Core Complex Contains a Homo-dimeric Catalytic Module for the Symmetric Mono-ubiquitination of FANCI-FANCD2

Directory of Open Access Journals (Sweden)

Paolo Swuec

2017-01-01

Full Text Available Activation of the main DNA interstrand crosslink repair pathway in higher eukaryotes requires mono-ubiquitination of FANCI and FANCD2 by FANCL, the E3 ligase subunit of the Fanconi anemia core complex. FANCI and FANCD2 form a stable complex; however, the molecular basis of their ubiquitination is ill defined. FANCD2 mono-ubiquitination by FANCL is stimulated by the presence of the FANCB and FAAP100 core complex components, through an unknown mechanism. How FANCI mono-ubiquitination is achieved remains unclear. Here, we use structural electron microscopy, combined with crosslink-coupled mass spectrometry, to find that FANCB, FANCL, and FAAP100 form a dimer of trimers, containing two FANCL molecules that are ideally poised to target both FANCI and FANCD2 for mono-ubiquitination. The FANCC-FANCE-FANCF subunits bridge between FANCB-FANCL-FAAP100 and the FANCI-FANCD2 substrate. A transient interaction with FANCC-FANCE-FANCF alters the FANCI-FANCD2 configuration, stabilizing the dimerization interface. Our data provide a model to explain how equivalent mono-ubiquitination of FANCI and FANCD2 occurs.

Effective search for stable segregation configurations at grain boundaries with data-mining techniques

Science.gov (United States)

Kiyohara, Shin; Mizoguchi, Teruyasu

2018-03-01

Grain boundary segregation of dopants plays a crucial role in materials properties. To investigate the dopant segregation behavior at the grain boundary, an enormous number of combinations have to be considered in the segregation of multiple dopants at the complex grain boundary structures. Here, two data mining techniques, the random-forests regression and the genetic algorithm, were applied to determine stable segregation sites at grain boundaries efficiently. Using the random-forests method, a predictive model was constructed from 2% of the segregation configurations and it has been shown that this model could determine the stable segregation configurations. Furthermore, the genetic algorithm also successfully determined the most stable segregation configuration with great efficiency. We demonstrate that these approaches are quite effective to investigate the dopant segregation behaviors at grain boundaries.

Spectrofluorimetric quantification of bilirubin using yttrium-norfloxacin complex as a fluorescence probe in serum samples

Energy Technology Data Exchange (ETDEWEB)

Kamruzzaman, Mohammad; Alam, Al-Mahmnur [Department of Chemistry, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Hak Lee, Sang, E-mail: shlee@knu.ac.kr [Department of Chemistry, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Ho Kim, Young, E-mail: youngkim@knu.ac.kr [Research Institute of Advanced Energy Technology, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Kim, Gyu-Man [School of Mechanical Engineering, Kyungpook National University, Daegu 702-701 (Korea, Republic of); Hyub Oh, Sang [Center for Gas Analysis, Korea Research Institute of Standards and Science, Daejeon 305-600 (Korea, Republic of)

2012-11-15

A simple and sensitive spectrofluorimetric method was developed to determine trace amounts of bilirubin (BR) using yttrium (Y{sup 3+})-norfloxacin (NFLX) complex as a fluorescence (FL) probe. NFLX can form a stable binary complex with Y{sup 3+} and markedly enhances the weak FL signal of the NFLX. The FL intensity of the Y{sup 3+}-NFLX complex decreased significantly in the presence of BR in a buffer solution at pH=7.2. Under optimal conditions, the FL intensity decreased according to the BR concentration and showed a good linear relationship in the range of 0.03-2.3 {mu}g mL{sup -1} of BR with a correlation coefficient of 0.9988. The limit of detection for the determination of BR was 2.8 ng mL{sup -1} with a relative standard deviation (RSD) of 1.55% for five replicate determination of 0.05 {mu}g mL{sup -1} BR. The presented method offers higher sensitivity with simple instrumentation and was applied successfully in detecting BR at low concentrations. Highlights: Black-Right-Pointing-Pointer Weak FL signal of NFLX was enhanced at 419 nm by forming binary complex with Y{sup 3+}. Black-Right-Pointing-Pointer The FL intensity of Y{sup 3+}-NFLX complex was quenched markedly in the presence of ATP. Black-Right-Pointing-Pointer NFLX can transfer energy to Y{sup 3+} and BR and form the Y{sup 3+}-NFLX-ATP ternary complex. Black-Right-Pointing-Pointer The reduced FL intensity of the system was correlated with the concentration of BR. Black-Right-Pointing-Pointer The method is applied to determine BR at low concentration (2.8 ng mL{sup -1}) in serum.