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Sample records for platinum pyrimidine greens

  1. Green synthesis and characterisation of platinum nanoparticles using quail egg yolk

    Science.gov (United States)

    Nadaroglu, Hayrunnisa; Gungor, Azize Alayli; Ince, Selvi; Babagil, Aynur

    2017-02-01

    Nanotechnology is extensively used in all parts today. Therefore, nano synthesis is also significant in all explored areas. The results of studies conducted have revealed that nanoparticle synthesis is performed by using both chemical and physical methods. It is well known that these syntheses are carried out at high charge, pressure and temperature in harsh environments. Therefore, this study investigated green synthesis method that sustains more mild conditions. In this study, quail egg yolk having high vitamin and protein content was prepared for green synthesis reaction and used for the synthesis of platinum nanoparticles in the reaction medium. Reaction situations were optimised as a function of pH, temperature, time and concentration by using quail egg yolk. The results showed that the highest platinum nanoparticles were synthesised at 20 °C and pH 6.0 for 4 h. Also, optimal concentration of metal ions was established as 0.5 mM. The synthesised platinum nanoparticles were characterised by using UV spectrum, X-ray diffraction and scanning electron microscope.

  2. Interaction of benzoate pyrimidine analogues with class 1A dihydroorotate dehydrogenase from Lactococcus lactis

    DEFF Research Database (Denmark)

    Wolfe, Abigail E; Thymark, Majbritt; Gattis, Samuel G

    2007-01-01

    Dihydroorotate dehydrogenases (DHODs) catalyze the oxidation of dihydroorotate to orotate in the only redox reaction in pyrimidine biosynthesis. The pyrimidine binding sites are very similar in all structurally characterized DHODs, suggesting that the prospects for identifying a class-specific in......-system of the flavin, resulting in a green color....

  3. Fieldwork measurement of indoor environmental quality (IEQ) in Malaysian platinum-rated green office buildings

    Science.gov (United States)

    Tharim, Asniza Hamimi Abdul; Samad, Muna Hanim Abdul; Ismail, Mazran

    2017-10-01

    An Indoor Environmental Quality (IEQ) fieldwork assessment was conducted in the Platinum-rated GBI office building located in Putrajaya Malaysia. The aim of the study is to determine the current indoor performance of the selected green office building. The field measurement consists of several IEQ parameters counted under the GBI Malaysia namely the Thermal Comfort of temperature, relative humidity, air movement and heat transfer as well as solar radiation. This field measurement also comprises of the measurement for the background noise, visual lighting and Indoor Air Quality (IAQ) focusing on the aspect of carbon dioxide concentration. All the selected indoor parameters were measured for the period of five working days and the results were compared to the Malaysian Standard. Findings of the field measurement show good indoor performance of the Platinum rated office building that complies with the GBI standard. It is hoped that the research findings will be beneficial for future design and construction of office building intended to be rated under the GBI Malaysia.

  4. Pyrimidine-pyridine ring interconversion

    NARCIS (Netherlands)

    Plas, van der H.C.

    2003-01-01

    This chapter discusses the pyrimidine-to-pyridine ring transformation and pyridine-to-pyrimidine ring transformation. In nucleophile-induced pyrimidine-to-pyridine rearrangements, two types of reactions can be distinguished depending on the structure of the nucleophile: (1) reactions in which the

  5. Tandem Aldol-Michael Reactions in Aqueous Diethylamine Medium: A Greener and Efficient Approach to Bis-Pyrimidine Derivatives

    Directory of Open Access Journals (Sweden)

    Abdullah M. Al-Majid

    2013-12-01

    Full Text Available A simple protocol, involving the green synthesis for the construction of novel bis-pyrimidine derivatives, 3a–i and 4a–e are accomplished by the aqueous diethylamine media promoted tandem Aldol-Michael reaction between two molecules of barbituric acid derivatives 1a,b with various aldehydes. This efficient synthetic protocol using an economic and environmentally friendly reaction media with versatility and shorter reaction time provides bis-pyrimidine derivatives with high yields (88%–99%.

  6. Synthesis and biological evaluation of some novel pyrido[1,2-a]pyrimidin-4-ones as antimalarial agents.

    Science.gov (United States)

    Mane, Uttam R; Mohanakrishnan, D; Sahal, Dinkar; Murumkar, Prashant R; Giridhar, Rajani; Yadav, Mange Ram

    2014-05-22

    Novel pyrido[1,2-a]pyrimidin-4-ones have been synthesized and evaluated for their antimalarial activity by SYBR Green I assay against erythrocytic stages of chloroquine (CQ) sensitive Pf 3D7 strain. The antimalarial screening of 42 different compounds revealed that 3-Fluorobenzyl(4-oxo-4H-pyrido [1,2-a]pyrimidin-3-yl)carbamate (21, IC50 value 33 μM) and 4-Oxo-N-[4-(trifluoromethyl)benzyl]-4H-pyrido[1,2-a]pyrimidine-3-carboxamide (37, IC50 value 37 μM) showed moderate antimalarial activity. Cytotoxicity study was performed against mammalian cell line (Huh-7) by using the MTT assay for the moderately active compounds. Structural activity relationship (SAR) studies displayed that B-ring unsubstituted pyrido[1,2-a]pyrimidine scaffold is responsible for the antimalarial activities of the evaluated derivatives. This SAR based antimalarial screening supported that pyrido[1,2-a]pyrimidin-4-one can be considered as a lead heterocyclic structure for further development of more potent derivatives for antimalarial activity. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  7. New pyrimidine based ligand capped gold and platinum nano particles: Synthesis, characterization, antimicrobial, antioxidant, DNA interaction and in vitro anticancer activities.

    Science.gov (United States)

    Sankarganesh, M; Adwin Jose, P; Dhaveethu Raja, J; Kesavan, M P; Vadivel, M; Rajesh, J; Jeyamurugan, R; Senthil Kumar, R; Karthikeyan, S

    2017-11-01

    In this research work, we have synthesized new pyrimidine based Schiff base ligand, 2-((4,6-dimethoxypyrimidine-2-yl)methyleneenamino)-6-methoxyphenol (DPMM) capped gold (Au) and platinum (Pt) nanoparticles (NPs) by modified Brust-Schiffrin method. The characteristics of DPMM-Au NPs and DPMM-Pt NPs have been examined by UV-Visible, FTIR, SEM, TEM and powder XRD analysis. SEM analysis result shows that surface morphology of the DPMM-Au NPs and DPMM-Pt NPs are in granular and spherical shape, correspondingly. The size of the DPMM-Au NPs and DPMM-Pt NPs are approximately 38.14±4.5 and 58.64±3.0nm respectively, which confirmed by TEM analysis. The DPMM-Au NPs and DPMM-Pt NPs have potent antimicrobial against Escherichia coli, Klebsiella pneumonia, Pseudomonas fluorescens, Shigella sonnei, Staphylococcus aureus and Aspergillus niger, Candida albicans, Candida tropicalis, Mucor indicus, Rhizopus strains. The DPMM-Au NPs and DPMM-Pt NPs have good antioxidant activities than the free ligand (DPMM). The spectroscopic and viscometric measurement confirms the hydrophobic DNA binding abilities of the newly prepared DPMM capped metal NPs. Moreover, the in vitro anticancer activity of DPMM, DPMM-Au NPs and DPMM-Pt NPs against cancer (MCF-7, HeLa & HEp2) and normal (NHDF) cell lines have performed using MTT assay. These results reveals that, DPMM-Au NPs and DPMM-Pt NPs having significant cytotoxic activity against the cancer cell lines and least toxic effect on normal cell line as compared to standard drug cisplatin. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Pyrimidine and halogenated pyrimidines near edge x-ray absorption fine structure spectra at C and N K-edges: experiment and theory

    International Nuclear Information System (INIS)

    Bolognesi, P.; O'Keeffe, P.; Ovcharenko, Y.; Coreno, M.; Avaldi, L.; Feyer, V.; Plekan, O.; Prince, K. C.; Zhang, W.; Carravetta, V.

    2010-01-01

    The inner shell excitation of pyrimidine and some halogenated pyrimidines near the C and N K-edges has been investigated experimentally by near edge x-ray absorption fine structure spectroscopy and theoretically by density functional theory calculations. The selected targets, 5-Br-pyrimidine, 2-Br-pyrimidine, 2-Cl-pyrimidine, and 5-Br-2-Cl-pyrimidine, allow the effects of the functionalization of the pyrimidine ring to be studied either as a function of different halogen atoms bound to the same molecular site or as a function of the same halogen atom bound to different molecular sites. The results show that the individual characteristics of the different spectra of the substituted pyrimidines can be rationalized in terms of variations in electronic and geometrical structures of the molecule depending on the localization and the electronegativity of the substituent.

  9. A Multimethod Approach for Investigating Algal Toxicity of Platinum Nanoparticles

    DEFF Research Database (Denmark)

    Sørensen, Sara Nørgaard; Engelbrekt, Christian; Lützhøft, Hans-Christian Holten

    2016-01-01

    The ecotoxicity of platinum nanoparticles (PtNPs) widely used in for example automotive catalytic converters, is largely unknown. This study employs various characterization techniques and toxicity end points to investigate PtNP toxicity toward the green microalgae Pseudokirchneriella subcapitata...

  10. Proficient synthesis of bioactive annulated pyrimidine derivatives: A review

    Directory of Open Access Journals (Sweden)

    Ajmal R. Bhat

    2017-11-01

    Full Text Available Syntheses of bioactive annulated pyrimidine derivatives are the most significant tasks in N-heterocyclic chemistry because these compounds have proved to be very attractive and useful for the design of new molecular frameworks of potential drugs with varying pharmacological activities. This review paper summarizes the one-pot multicomponent synthesis of annulated nitrogen- and oxygen-containing heterocycles, such as pyrano[2,3-d]pyrimidines, pyrido[2,3-d]pyrimidines and pyrido[2,3-d;5-6-d]dipyrimidines. The synthetic procedure is based on the chemistry of the domino Knoevenagel-Michael addition mechanism. Keywords: Pyrano[2,3-d]pyrimidines, Pyrido[2,3-d]pyrimidines, Pyrido[2,3-d;5-6-d]dipyrimidines, Barbituric acid/Thio-barbituric acid, Aromatic aldehydes, 6-aminouracil

  11. Isotopically labelled pyrimidines and purines

    International Nuclear Information System (INIS)

    Balaban, A.T.; Bally, I.

    1987-01-01

    Among the three diazines, pyrimidine is by far the most important one because its derivatives uracil, thymine and cytosine are constituents of the ubiquitous deoxynucleic acids (DNA) and ribonucleic acids (RNA). Other derivatives of pyrimidine without condensed rings include barbiturates, alloxan, orotic acid and thiamine or vitamin B 1 . From the polycyclic derivatives of pyrimidine such as pteridine, alloxazine, and purine, the latter, through its derivatives adenine and guanine complete the list of bases which occur in DNA and RNA: in addition, other purine derivatives such as hypoxanthine, xanthine, theobromine, theophylline, caffeine and uric acid are important natural products with biological activity. The paper presents methods for preparing isotopically labeled pyrimidines as well as purine derivatives. For convenience, the authors describe separately carbon-labeled with radioisotopes 11 C (T 1/2 = 20.3 min) and 14 C (T 1/2 = 5736 years) or the stable isotope 13 C (natural abundance 1.1%) and then hydrogen-labeled systems with the radioisotope 3 H ≡ T (T 1/2 = 12.346 years) or with the stable isotope 2 H ≡ D (natural abundance 0.015%). We do not separate stable from radioactive isotopes because the synthetic methods are identical for the same element; however, the introduction of hydrogen isotopes into organic molecules is often performed by reactions such as isotope exchange which cannot take place in the case of carbon isotopes

  12. 1.7 nm Platinum Nanoparticles: Synthesis with Glucose Starch, Characterization and Catalysis

    DEFF Research Database (Denmark)

    Engelbrekt, Christian; Sørensen, Karsten Holm; Lubcke, T.

    2010-01-01

    Monodisperse platinum nanoparticles (PtNPs) were synthesized by a green recipe. Glucose serves as a reducing agent and starch as a stabilization agent to protect the freshly formed PtNP cores in buffered aqueous solutions. Among the ten buffers studied, 2-(N-morpholino)ethanesulfonic acid (MES), ...

  13. Electron scattering from pyrimidine

    International Nuclear Information System (INIS)

    Colmenares, Rafael; Fuss, Martina C; García, Gustavo; Oller, Juan C; Muñoz, Antonio; Blanco, Francisco; Almeida, Diogo; Limão-Vieira, Paulo

    2014-01-01

    Electron scattering from pyrimidine (C 4 H 4 N 2 ) was investigated over a wide range of energies. Following different experimental and theoretical approaches, total, elastic and ionization cross sections as well as electron energy loss distributions were obtained.

  14. Green buildings need good ergonomics.

    Science.gov (United States)

    Hedge, A; Dorsey, J A

    2013-01-01

    A retrospective post-occupancy evaluation survey of 44 occupants in two Leadership in Energy and Environmental Design (LEED) Platinum buildings on a US college campus is reported. The Internet survey covered a range of indoor environment and ergonomics issues. Results show that working in these buildings were a generally positive experience for their health, performance and satisfaction. However, in one building there were persistent issues of variability in air temperature, air freshness, air quality and noise that affected the perceived health and performance of the occupants. Although the buildings were energy-efficient and sustainable structures, ergonomics design issues were identified. Implications for the role of ergonomics in green buildings and in the US LEED rating system are discussed. This survey identified a number of ergonomics design issues present in the LEED Platinum energy-efficient and sustainable buildings that were studied. These results highlight the importance of integrating ergonomics design into green buildings as a component in the US LEED rating system.

  15. Presidential Green Chemistry Challenge: 2016 Academic Award

    Science.gov (United States)

    Presidential Green Chemistry Challenge 2016 award winner, Professor Chirik, discovered a class of catalysts used to produce silicones for consumer goods without using hard-to-mine platinum (less mining, reduces costs, greenhouse gas emissions, and waste).

  16. Method development and validation of potent pyrimidine derivative by UV-VIS spectrophotometer.

    Science.gov (United States)

    Chaudhary, Anshu; Singh, Anoop; Verma, Prabhakar Kumar

    2014-12-01

    A rapid and sensitive ultraviolet-visible (UV-VIS) spectroscopic method was developed for the estimation of pyrimidine derivative 6-Bromo-3-(6-(2,6-dichlorophenyl)-2-(morpolinomethylamino) pyrimidine4-yl) -2H-chromen-2-one (BT10M) in bulk form. Pyrimidine derivative was monitored at 275 nm with UV detection, and there is no interference of diluents at 275 nm. The method was found to be linear in the range of 50 to 150 μg/ml. The accuracy and precision were determined and validated statistically. The method was validated as a guideline. The results showed that the proposed method is suitable for the accurate, precise, and rapid determination of pyrimidine derivative. Graphical Abstract Method development and validation of potent pyrimidine derivative by UV spectroscopy.

  17. complexes of pyrimidine derived

    Indian Academy of Sciences (India)

    Administrator

    The ligands are prepared by the condensation of 4,6-dimethyl 2-hydrazino pyrimidine with salicylaldehyde ... 6. With the knowledge of approximate coordination sphere of Mo in the metal- loenzymes at hand, several attempts have been made to model the active sites of these enzymes and study ..... [I > 2 sigma(I)]R indices.

  18. Solvent extraction of platinum with thiobenzanilide. Separation of platinum from copper

    International Nuclear Information System (INIS)

    Shkil', A.N.; Zolotov, Yu.A.

    1989-01-01

    The solvent extraction of micro concentrations of platinum has been investigated from hydrochloric acid media using thiobenzanilide in the presence of SnCl 2 and KI. In the presence of SnCl 2 platinum is extracted rapidly and to significant completion. Conditions have been developed for the quantitative extraction of platinum. The authors have also examined the solvent extraction of copper(II) using thiobenzanilide, interference due to copper(II) and iron(III) on solvent extraction of platinum, and methods to suppress this interference. A procedure has also been developed for the separation of platinum from copper. Solvent extraction of metals was studied using radioactive isotopes: 197 Pt, 64 Cu, 59 Fe, 198 Au, 109 Pd, 110m Ag

  19. Opto-electronic properties of quasi-linear, self-assembled platinum complexes : Pt-Pt distance dependence

    NARCIS (Netherlands)

    Debije, M.G.; Haas, de M.P.; Warman, J.M.; Fontana, M.; Stutzmann, N.; Kristiansen, M.; Caseri, W.R.; Smith, P.; Hoffmann, S.; Solling, T. I.

    2004-01-01

    Charge-carrier mobilities of various self-assembled platinum complexes were measured by time-resolved microwave conductivity techniques in the temperature range –80 to +100¿°C. Eight compounds were investigated in the present study, including the original Magnus' green salt ([Pt(NH3)4][PtCl4]) and

  20. Discovery of 4-anilino-N-methylthieno[3,2-d]pyrimidines and 4-anilino-N-methylthieno[2,3-d]pyrimidines as potent apoptosis inducers.

    Science.gov (United States)

    Kemnitzer, William; Sirisoma, Nilantha; May, Chris; Tseng, Ben; Drewe, John; Cai, Sui Xiong

    2009-07-01

    We report the discovery of N-((benzo[d][1,3]dioxol-5-yl)methyl)-6-phenylthieno[3,2-d]pyrimidin-4-amine (2a) as an apoptosis inducer using our proprietary cell- and caspase-based ASAP HTS assay, and SAR study of HTS hit 2a which led to the discovery of 4-anilino-N-methylthieno[3,2-d]pyrimidines and 4-anilino-N-methylthieno[2,3-d]pyrimidines as potent apoptosis inducers. Compounds 5d and 5e were the most potent with EC(50) values of 0.008 and 0.004microM in T47D human breast cancer cells, respectively. Compound 5d was found to be highly active in the MX-1 breast cancer model. Functionally, compounds 5d and 5e both induced apoptosis through inhibition of tubulin polymerization.

  1. Platinum metals in the environment

    Energy Technology Data Exchange (ETDEWEB)

    Zereini, Fathi [Frankfurt Univ. (Germany). Dept. of Environmental Analytical Chemistry; Wiseman, Clare L.S. (ed.) [Toronto Univ. (Canada). School of the Environment

    2015-03-01

    This book contains the five chapters with the following topics: 1. SOURCES OF PGE EMISSIONS ELEMENTS: Sources of Platinum Group Elements (PGE) in the Environment; Impact of Platinum Group Element Emissions from Mining and Production Activities. 2. ANALYTICAL METHODS FOR THE DETERMINATION OF PGE IN BIOLOGICAL AND ENVIRONMENTAL MATRICES: Appraisal of Biosorption for Recovery, Separation and Determination of Platinum, Palladium and Rhodium in Environmental Samples; On the Underestimated Factors Influencing the Accuracy of Determination of Pt and Pd by Electrothermal Atomic Absorption Spectrometry in Road Dust Samples; Application of Solid Sorbents for Enrichment and Separation of Platinum Metal Ions; Voltammetric Analysis of Platinum in Environmental Matrices; Speciation Analysis of Chloroplatinates; Analysis of Platinum Group Elements in Environmental Samples: A Review. 3. OCCURRENCE, CHEMICAL BEHAVIOR AND FATE OF PGE IN THE ENVIRONMENT: Brazilian PGE Research Data Survey on Urban and Roadside Soils; Platinum, Palladium and Rhodium in a Bavarian Roadside Soil; Increase of Platinum Group Element Concentrations in Soils and Airborne Dust During the Period of Vehicular Exhaust Catalysts Introduction; Platinum-Group Elements in Urban Fluvial Bed Sediments-Hawaii; Long-Term Monitoring of Palladium and Platinum Contents in Road Dust of the City of Munich, Germany; Characterization of PGEs and Other Elements in Road Dusts and Airborne Particles in Houston, Texas; Accumulation and Distribution of Pt and Pd in Roadside Dust, Soil and Vegetation in Bulgaria; Increase of the Environmental Pt Concentration in the Metropolitan Area of Mexico City Associated to the Use of Automobile Catalytic Converters; Solubility of Emitted Platinum Group Elements (Pt, Pd and Rh) in Airborne Particulate Matter (PM10) in the Presence of Organic Complexing Agents; The Influence of Anionic Species (Cl{sup -}, NO{sub 3}{sup -}, SO{sub 4}{sup 2-}) on the Transformation and Solubility of Platinum in

  2. Significance and Biological Importance of Pyrimidine in the Microbial World

    Directory of Open Access Journals (Sweden)

    Vinita Sharma

    2014-01-01

    Full Text Available Microbes are unique creatures that adapt to varying lifestyles and environment resistance in extreme or adverse conditions. The genetic architecture of microbe may bear a significant signature not only in the sequences position, but also in the lifestyle to which it is adapted. It becomes a challenge for the society to find new chemical entities which can treat microbial infections. The present review aims to focus on account of important chemical moiety, that is, pyrimidine and its various derivatives as antimicrobial agents. In the current studies we represent more than 200 pyrimidines as antimicrobial agents with different mono-, di-, tri-, and tetrasubstituted classes along with in vitro antimicrobial activities of pyrimidines derivatives which can facilitate the development of more potent and effective antimicrobial agents.

  3. Strains of Lactococcus lactis with a partial pyrimidine requirement show sensitivity toward aspartic acid

    DEFF Research Database (Denmark)

    Wadskov-Hansen, Steen Lyders Lerche; Martinussen, Jan

    2009-01-01

    The growth rate of the widely used laboratory strain Lactococcus lactis subsp. cremoris LM0230 was reduced if aspartic acid were present in the growth medium. The strain LM0230 is a plasmid- and phage-cured derivative of L. lactis subsp. cremoris C2, the ancestor of the original dairy isolate L...... with the wild-type strain, and this varied with the concentration of aspartic acid. The observed effect of aspartate could be explained by the accumulation of the toxic pyrimidine de novo pathway intermediate, carbamoyl aspartate. Assays of the pyrimidine biosynthetic enzymes of L. lactis LM0230 showed...... that the partial pyrimidine requirement can be explained by a low specific activity of the pyrimidine biosynthetic enzymes. In conclusion, L. lactis LM0230 during the process of plasmid- and prophage-curing has acquired a partial pyrimidine requirement resulting in sensitivity toward aspartic acid....

  4. Electron and positron interaction with pyrimidine: A theoretical investigation

    Science.gov (United States)

    Sinha, Nidhi; Antony, Bobby

    2018-03-01

    Pyrimidine (C4H4N2) is considered as the building block of nucleobases, viz., cytosine, thymine and uracil. They provide a blueprint for probing the scattering of radiation by DNA and RNA bases. In this article, we report the elastic and total scattering cross-sections for electron and positron scattering from the pyrimidine molecule, employing a spherical complex optical potential (SCOP) formalism for an extensive energy range of 10 eV to 5 keV. In the case of positron scattering, the original SCOP formalism is modified to adequately solve the positron-target dynamics. Moreover, a reasonable agreement is observed between the present results and other available datasets, for both electron and positron scattering. The cross-sections for electron and positron impact scattering by pyrimidine are necessary input data for codes that seek to simulate radiation damage, and hence are useful to model biomolecular systems.

  5. Interaction of quinones with three pyrimidine bases: A laser flash photolysis study

    Energy Technology Data Exchange (ETDEWEB)

    Bose, Adity [Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India); Basu, Samita, E-mail: samita.basu@saha.ac.i [Chemical Sciences Division, Saha Institute of Nuclear Physics, 1/AF Bidhannagar, Kolkata 700064 (India)

    2009-11-15

    The interaction between three different pyrimidine bases, uracil (U), cytosine (C) and thymine (T) and two quinones, 2-methyl-1,4-naphthoquinone or menadione (MQ) and 9,10-anthraquinone (AQ) have been studied using laser flash photolysis technique in organic homogeneous medium. The three pyrimidines have revealed a difference in their extent of reactivity towards the quinones, which has been attributed to their structural difference. Our works have revealed that the difference in structural dimension of the quinones is also responsible for affecting the reactivity of these pyrimidines in homogeneous medium.

  6. Interaction of quinones with three pyrimidine bases: A laser flash photolysis study

    International Nuclear Information System (INIS)

    Bose, Adity; Basu, Samita

    2009-01-01

    The interaction between three different pyrimidine bases, uracil (U), cytosine (C) and thymine (T) and two quinones, 2-methyl-1,4-naphthoquinone or menadione (MQ) and 9,10-anthraquinone (AQ) have been studied using laser flash photolysis technique in organic homogeneous medium. The three pyrimidines have revealed a difference in their extent of reactivity towards the quinones, which has been attributed to their structural difference. Our works have revealed that the difference in structural dimension of the quinones is also responsible for affecting the reactivity of these pyrimidines in homogeneous medium.

  7. Growth and sporulation of a pyrimidine spore color mutant of Sordaria fimicola.

    Science.gov (United States)

    el-Ani, A S

    1967-04-07

    A nonautonomous spore color mutant of Sordaria fimicola is a pyrimidine auxotroph that produces hyaline nonviable ascospores. Uracil, uridine, and cytidine are more effective growth factors than cytosine and thymine and, in high concentrations, render the mutant self-fertile by inducing the ascospores to resume development and maturation. Crosses with the unlinked arginine non-autonomus spore color mutant st-59 yielded the double mutant st-59 pyr that requires both arginine and a pyrimidine for growth, which indicates a lack of suppression of the pyrimidine requirement by the arginine locus.

  8. Studies on Synthesis of Pyrimidine Derivatives and their Pharmacological Evaluation

    Directory of Open Access Journals (Sweden)

    T. A. Naik

    2007-01-01

    Full Text Available 1,3,4-Oxadiazoles were associated with broad spectrum of biological activities including antituberculosis, anticonvulsant, anti-inflammatory, insecticidal, antifungal, analgesic and antitumor properties. Morpholine derivatives find their wide spectrum of antimicrobial activity and exhibit anthelmintic, bactericidal and insecticidal activity. Pyrimidine derivatives are also reported to possess antibacterial, antimicrobial, antifungal, anticancer and anticonvulsant activities. Encouraged by this observations we decided to synthesised novel pyrimidine derivatives.

  9. Pyrimidines in antimalarial drug design

    CSIR Research Space (South Africa)

    Moleele, SS

    2008-09-01

    Full Text Available of the routes attempted are shown in Scheme 1. Pyrimidines In Antimalarial Drug Design S S Moleele1, D Gravestock1, A L Rousseau1, R L Van Zyl2 1Discovery Chemistry, CSIR, Biosciences, Private Bag X2, Modderfontein, 1645, South Africa; SMoleele@csir.co.za 2...

  10. Adsorption and temperature-programmed desorption of hydrogen with dispersed platinum and platinum-gold catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, J.R.; Foger, K.; Breakspere, R.J.

    1979-05-01

    Adsorption and temperature-programmed desorption of hydrogen with dispersed platinum and platinum-gold catalysts was studied with 0.9-3Vertical Bar3< platinum on silica gel, aerosil, sodium and lanthanum Y zeolites, and ..gamma..-alumina, and on aerosil-supported gold-platinum alloys containing 2, 10, 24, 33, and 85Vertical Bar3< gold. Surface enrichment with gold in the alloy systems, as derived from hydrogen adsorption data and predicted from surface enrichment theory and electron microscopic measurements of particle size, were in good agreement, which indicated that equilibrium was achieved by the thermal treatment (oxygen at 573/sup 0/K, hydrogen at 620/sup 0/K, repeated cycles) used. Hydrogen spillover to gold was observed at the higher hydrogen pressures tested on the alloys with high gold content, and to the zeolite supports. The temperature-programed desorption profiles were independent of gold content, which indicated that gold acts only as diluent, and that isolated surface platinum atoms become populated with hydrogen atoms either by hydrogen atom spillover from platinum ensembles to gold and from the gold to the isolated platinum, and/or by adsorption of a molecule directly on the isolated platinum and chemisorption of one H atom at an adjacent gold atom. The distribution of surface platinum ensembles was evaluated by a computer simulation method.

  11. Chemical evolution. XXIX - Pyrimidines from hydrogen cyanide

    Science.gov (United States)

    Ferris, J. P.; Joshi, P. C.; Lawless, J. G.

    1978-01-01

    Compounds obtained by hydrolysis of HCN oligomers formed by allowing pH 9.2, 0.1 M cyanide to stand at room temperature for 4 to 12 months were analyzed. Hydrolysis of HCN oligomers yielded 4,5-dihydroxypyrimidine and 5-hydroxyuracil; orotic acid was detected after hydrolysis at pH 8.5. A unified pathway from diaminofumaronitrile to the pyrimidines observed is suggested. As purines, pyrimidines and amino acids are released by hydrolysis of HCN oligomers in either acidic or mildly basic aqueous solutions, they could have been formed on the primitive earth in spite of fluctuations in pH. 4,5-dihydroxypyrimidines appear to be likely candidates for incorporation into primitive nucleic acids, as they should undergo Watson-Crick hydrogen bonding with adenine.

  12. Rhodium(III)-Catalyzed ortho-Alkylation of Phenoxy Substrates with Diazo Compounds via C-H Activation: A Case of Decarboxylative Pyrimidine/Pyridine Migratory Cyclization Rather than Removal of Pyrimidine/Pyridine Directing Group.

    Science.gov (United States)

    Ravi, Manjula; Allu, Srinivasarao; Swamy, K C Kumara

    2017-03-03

    An efficient Rh(III)-catalyzed ortho-alkylation of phenoxy substrates with diazo compounds has been achieved for the first time using pyrimidine or pyridine as the directing group. Furthermore, bis-alkylation has also been achieved using para-substituted phenoxypyrimidine and 3 mol equiv of the diazo ester. The ortho-alkylated derivatives of phenoxy products possessing the ester functionality undergo decarboxylative pyrimidine/pyridine migratory cyclization (rather than deprotection of pyrimidine/pyridine group) using 20% NaOEt in EtOH affording a novel class of 3-(pyrimidin-2(1H)-ylidene)benzofuran-2(3H)-ones and 6-methyl-3-(pyridin-2(1H)-ylidene)benzofuran-2(3H)-one. The ortho-alkylated phenoxypyridine possessing ester functionality also undergoes decarboxylative pyridine migratory cyclization using MeOTf/NaOMe in toluene providing 6-methyl-3-(1-methylpyridin-2(1H)-ylidene)benzofuran-2(3H)-one.

  13. A Novel and Efficient Five-Component Synthesis of Pyrazole Based Pyrido[2,3-d]pyrimidine-diones in Water: A Triply Green Synthesis

    Directory of Open Access Journals (Sweden)

    Majid M. Heravi

    2016-04-01

    Full Text Available A novel one pot synthesis of pyrazolo[4′,3′:5,6]pyrido[2,3-d]pyrimidine-diones, via a five-component reaction, involving, hydrazine hydrate, ethyl acetoacetate, and 1,3-dimethyl barbituric acid, an appropriate aryl aldehydes and ammonium acetate catalyzed via both of heterogeneous and homogeneous catalysis in water, is reported.

  14. Gene set analysis of purine and pyrimidine antimetabolites cancer therapies.

    Science.gov (United States)

    Fridley, Brooke L; Batzler, Anthony; Li, Liang; Li, Fang; Matimba, Alice; Jenkins, Gregory D; Ji, Yuan; Wang, Liewei; Weinshilboum, Richard M

    2011-11-01

    Responses to therapies, either with regard to toxicities or efficacy, are expected to involve complex relationships of gene products within the same molecular pathway or functional gene set. Therefore, pathways or gene sets, as opposed to single genes, may better reflect the true underlying biology and may be more appropriate units for analysis of pharmacogenomic studies. Application of such methods to pharmacogenomic studies may enable the detection of more subtle effects of multiple genes in the same pathway that may be missed by assessing each gene individually. A gene set analysis of 3821 gene sets is presented assessing the association between basal messenger RNA expression and drug cytotoxicity using ethnically defined human lymphoblastoid cell lines for two classes of drugs: pyrimidines [gemcitabine (dFdC) and arabinoside] and purines [6-thioguanine and 6-mercaptopurine]. The gene set nucleoside-diphosphatase activity was found to be significantly associated with both dFdC and arabinoside, whereas gene set γ-aminobutyric acid catabolic process was associated with dFdC and 6-thioguanine. These gene sets were significantly associated with the phenotype even after adjusting for multiple testing. In addition, five associated gene sets were found in common between the pyrimidines and two gene sets for the purines (3',5'-cyclic-AMP phosphodiesterase activity and γ-aminobutyric acid catabolic process) with a P value of less than 0.0001. Functional validation was attempted with four genes each in gene sets for thiopurine and pyrimidine antimetabolites. All four genes selected from the pyrimidine gene sets (PSME3, CANT1, ENTPD6, ADRM1) were validated, but only one (PDE4D) was validated for the thiopurine gene sets. In summary, results from the gene set analysis of pyrimidine and purine therapies, used often in the treatment of various cancers, provide novel insight into the relationship between genomic variation and drug response.

  15. Biosorption of platinum and palladium for their separation/preconcentration prior to graphite furnace atomic absorption spectrometric determination

    Energy Technology Data Exchange (ETDEWEB)

    Godlewska-Zylkiewicz, Beata E-mail: bgodlew@uwb.edu.pl

    2003-08-15

    Inexpensive baker's yeast Saccharomyces cerevisiae and green algae Chlorella vulgaris, either free or immobilized on silica gel have been shown to selectively accumulate platinum and palladium from water samples in acidic medium (pH 1.6-1.8). Optimization of conditions of metals biosorption (sample pH, algae and yeast masses, adsorption time, temperature) was performed in batch mode. The procedure of matrix separation based on biosorption of platinum and palladium on algae C. vulgaris covalently immobilized on silica gel in flow mode was developed. The use of algae in flow procedure offers several advantages compared with its use in the batch mode. The procedure shows better reproducibility (<2%), improved efficiency of platinum retention on the column (93.3{+-}1.6%), is less laborious and less time consuming. The best recovery of biosorbed metals from column (87.7{+-}3.3% for platinum and 96.8{+-}1.1 for palladium) was obtained with solution of 0.3 mol l{sup -1} thiourea in 1 mol l{sup -1} hydrochloric acid. The influence of thiourea on analytical signals of examined metals during GFAAS determination is discussed. The procedure has been applied for separation of noble metals from tap and waste water samples spiked with platinum and palladium.

  16. Catabolism of pyrimidines in yeast: A tool to understand degradation of anticancer drugs

    DEFF Research Database (Denmark)

    Andersen, Gorm; Merico, A.; Bjornberg, O.

    2006-01-01

    The pyrimidine catabolic pathway is of crucial importance in cancer patients because it is involved in degradation of several chemotherapeutic drugs, such as 5-fluorouracil; it also is important in plants, unicellular eukaryotes, and bacteria for the degradation of pyrimidine-based biocides/antib...

  17. Blockage of the pyrimidine biosynthetic pathway affects riboflavin production in Ashbya gossypii.

    Science.gov (United States)

    Silva, Rui; Aguiar, Tatiana Q; Domingues, Lucília

    2015-01-10

    The Ashbya gossypii riboflavin biosynthetic pathway and its connection with the purine pathway have been well studied. However, the outcome of genetic alterations in the pyrimidine pathway on riboflavin production by A. gossypii had not yet been assessed. Here, we report that the blockage of the de novo pyrimidine biosynthetic pathway in the recently generated A. gossypii Agura3 uridine/uracil auxotrophic strain led to improved riboflavin production on standard agar-solidified complex medium. When extra uridine/uracil was supplied, the production of riboflavin by this auxotroph was repressed. High concentrations of uracil hampered this (and the parent) strain growth, whereas excess uridine favored the A. gossypii Agura3 growth. Considering that the riboflavin and the pyrimidine pathways share the same precursors and that riboflavin overproduction may be triggered by nutritional stress, we suggest that overproduction of riboflavin by the A. gossypii Agura3 may occur as an outcome of a nutritional stress response and/or of an increased availability in precursors for riboflavin biosynthesis, due to their reduced consumption by the pyrimidine pathway. Copyright © 2014 Elsevier B.V. All rights reserved.

  18. Punica granatum fabricated platinum nanoparticles: A therapeutic pill for breast cancer

    Science.gov (United States)

    Jha, Babita; Rao, Mugdha; Chattopadhyay, A.; Bandyopadhyay, A.; Prasad, K.; Jha, Anal K.

    2018-05-01

    The current research highlights the fabrication of biocompatible platinum nanoparticles (Pt NPs) in first hand from arils of Punica granatum by using green chemistry approach. Formation of Pt NPs was determined by UV-visible, X-ray diffraction, and FTIR techniques. The anti-cancer potential of fabricated Pt NPs was evaluated by MTT assay on MCF7 and MDA-MB-231 breast cancer cell lines. This work is foreshadowing the prospect of Pt NPs application as a therapeutic drug for cancer treatment.

  19. A study of anti-inflammatory and analgesic activity of new 2,4,6-trisubstituted pyrimidines.

    Science.gov (United States)

    Yejella, Rajendra Prasad; Atla, Srinivasa Rao

    2011-01-01

    Chalcone derivatives (3a-m) were prepared by condensing 4-aminoacetophenone with various substituted aromatic and hetero aromatic aldehydes according to Claisen-Schmidt condensation. These chalcones, on reaction with guanidine hydrochloride under basic alcoholic conditions gave 2,4,6-trisubstituted pyrimidines (5a-m) in quantitative yields. All the newly synthesized pyrimidines were characterized by means of IR, ¹H- and ¹³C-NMR, Electron Ionization (EI)-mass and elemental analyses and screened for anti-inflammatory and analgesic activities by in vivo. 2-amino-4-(4-aminophenyl)-6-(2,4-dichlorophenyl)pyrimidine (5b) and 2-amino-4-(4-aminophenyl)-6-(3-bromophenyl) pyrimidine (5d) were found to be the most potent anti-inflammatory and analgesic activity compared with ibuprofen, reference standard. And also it was found that compound 5b identified as lead structure among all in both the activities. Pyrimidines which showed good anti-inflammatory activity also displayed better analgesic activity.

  20. Increase in urinary purines and pyrimidines in patients with methylmalonic aciduria combined with homocystinuria.

    Science.gov (United States)

    Porcu, Simona; Corda, Marcella; Lilliu, Franco; Contini, Liliana; Era, Benedetta; Traldi, Pietro; Fais, Antonella

    2010-06-03

    Methylmalonic aciduria combined with homocystinuria (MMA-HC) is the biochemical trait of a metabolic disorder resulting from impaired conversion of dietary cobalamin (cbl, or vitamin B12) to its two metabolically active forms. Effects on urinary purine and pyrimidine levels have not been described for this condition. Urine samples were collected from three patients with methylmalonic aciduria combined with homocystinuria and from 70 healthy subjects. Urinary purine and pyrimidine levels were quantitated by the use of LC/UV-Vis and LC/ESI/MS. Higher urine levels of pyrimidines were detected with both methods in patients compared to controls. Methylmalonic aciduria with homocystinuria is due to deficiency of the enzyme, cobalamin reductase. The enzyme defect leads to altered hepatic metabolism, which appears to modify circulating pyrimidine levels. Copyright 2010 Elsevier B.V. All rights reserved.

  1. Electrochemical behavior of some new pyrimidine derivatives

    Directory of Open Access Journals (Sweden)

    MUSTAFA LUTFU BERKEM

    2004-09-01

    Full Text Available Electrochemical reduction of two recently synthesized pyrimidine compounds, 1-amino-5-benzoyil-4-phenyl-1H-pyrimidine-2-one (I, and 1-amino-5-benzoil-4-phenyl-1H-pyrimidine-2-thione (II were investigated by cyclic volatmmetry at a hanging mercury drop electrode in aqueous methanol (36 % v/v and in non-aqueous methanol. A series of cathodic peaks without the corresponding anodic peaks were observed for I. As the pH of the solution was increased, some of the cathodic peaks overlapped resulting in the loss of the previously observed peaks. For II, three cathodic peaks and one anodic peak were observed in addition to those observed for I. The peak potentials shifted in the negative direction with increasing pH. This shift was measured over a large pH range (1.80 – 12.30 to determine the pKa values of the compounds. The acidity constants related to the amino groups were 4.80 and 9.80 for I and 5.50 and 9.80 for II. A thiol-thione tautomerization was observed for II, which was more pronounced in the non-aqueous methanol medium. The pK values for both protonation and deprotonation of the thiocarbonyl group were also determined. The pK values were 5.80 and 9.80 for protonation and deprotonation in aqueous methanol and 6.80 and 10.80 in non-aqueous methanol.

  2. Reactions of neopentane and neohexane on platinum/Y-zeolite and platinum/silica catalysts

    Energy Technology Data Exchange (ETDEWEB)

    Foger, K.; Anderson, J.R.

    1978-10-13

    The hydrocracking/hydroisomerization reaction of 20:1 hydrogen/neopentane at 455-625/sup 0/K was studied on platinum-exchanged sodium, calcium, and lanthanum Y zeolites and Aerosil-supported platinum of 1-20 nm average platinum particle size, by analysis of the product distribution, ESCA, and temperature-programed desorption. The results suggested that the reaction occurs only on platinum and that it proceeds by two parallel pathways which have different activation energies and whose relative proportion depends on the particle size. One pathway is the conventionally accepted one on low-index crystallite facets; the other proceeds on single-surface platinum atoms of low coordination (corner or edge atoms) which become more abundant at lower crystallite size. In both cases, the adsorbed intermediate may undergo either isomerization or hydrogenolysis; the selectivity depends on the hydrogen partial pressure and the relative strength of adsorption of hydrogen and neopentane. Neohexane isomerization selectivity on the same catalysts is consistent with a carbonium ion mechanism on a dual-function catalyst.

  3. Privileged substructure-based diversity-oriented synthesis pathway for diverse pyrimidine-embedded polyheterocycles

    DEFF Research Database (Denmark)

    Kim, Heejun; Thanh Tung, Truong; Park, Seung Bum

    2013-01-01

    A new diversity-oriented synthesis pathway for the fabrication of a pyrimidine-embedded polyheterocycles library was developed for potential interactions with diverse biopolymers. Five different pyrimidine-embedded core skeletons were synthesized from ortho-alkynylpyrimidine carbaldehydes by a si...... by a silver- or iodine-mediated tandem cyclization strategy. The resulting polyheterocycles possess diverse fused ring sizes and positions with potential functionalities for further modification....

  4. Mutability of bacteriophage M13 by ultraviolet light: role of pyrimidine dimers

    International Nuclear Information System (INIS)

    Schaaper, R.M.; Glickman, B.W.

    1982-01-01

    The role of pyrimidine dimers in mutagenesis by ultraviolet light was examined by measuring the UV-induced reversion of six different bacteriophage M13 amber mutants for which the neighboring DNA sequences are known. The mutational response at amber (TAG) codons preceded by a guanine or adenine (where no pyrimidine dimer can be formed) were compared with those preceded by thymine or cytosine (where dimer formation is possible). Equivalent levels of UV-induced mutagenesis were observed at both kinds of sites. This observation demonstrates that there is no requirement for a pyrimidine dimer directly at the site of UV-induced mutation in this single-stranded DNA phage. UV irradiation of the phage was also performed in the presence of Ag + ions, which specifically sensitize the DNA to dimer formation. The two methods of irradiation, when compared at equal survival levels (and presumably equal dimer frequencies), produced equivalent frequencies of reversion of the amber phage. We believe these results indicate that while the presence of pyrimidine dimers may be a prerequisite for UV mutagenesis, the actual mutagenic event can occur at a site some distance removed from a dimer. (orig.)

  5. Hydrogenation of hexene over platinum on alumina vs. platinum in a Na-Y zeolite

    International Nuclear Information System (INIS)

    Miner, R.S. Jr.; Ione, K.G.; Namba, S.; Turkevich, J.

    1978-01-01

    In order to study the efficacy of zeolites as supports, several platinum H--Y zeolites were prepared by ion exchanging an H--Y zeolite with Pt(NH 3 ) 4 Cl 2 and reducing these products with hydrazine hydrate (A, B, C). Another preparation was made by adsorbing 32-A platinum sol on the zeolite crystallites (D). These catalysts were studied for hydrogenation and isomerization of hexene-1, ethylene hydrogenation, hydrogen chemisorption, and poison titration. They were compared with monodisperse Pt (32 A diameter) on alumina. A marked difference was found between the behavior of hexene-1 with the platinum-in-zeolite and with the platinum-on-alumina

  6. Phosphoric acid fuel cell platinum use study

    Science.gov (United States)

    Lundblad, H. L.

    1983-05-01

    The U.S. Department of Energy is promoting the private development of phosphoric acid fuel cell (PAFC) power plants for terrestrial applications. Current PAFC technology utilizes platinum as catalysts in the power electrodes. The possible repercussions that the platinum demand of PAFC power plant commercialization will have on the worldwide supply and price of platinum from the outset of commercialization to the year 2000 are investigated. The platinum demand of PAFC commercialization is estimated by developing forecasts of platinum use per unit of generating capacity and penetration of PAFC power plants into the electric generation market. The ability of the platinum supply market to meet future demands is gauged by assessing the size of platinum reserves and the capability of platinum producers to extract, refine and market sufficient quantities of these reserves. The size and timing of platinum price shifts induced by the added demand of PAFC commercialization are investigated by several analytical methods. Estimates of these price shifts are then used to calculate the subsequent effects on PAFC power plant capital costs.

  7. Pyrimidine nucleobase radical reactivity in DNA and RNA

    Science.gov (United States)

    Greenberg, Marc M.

    2016-11-01

    Nucleobase radicals are major products of the reactions between nucleic acids and hydroxyl radical, which is produced via the indirect effect of ionizing radiation. The nucleobase radicals also result from hydration of cation radicals that are produced via the direct effect of ionizing radiation. The role that nucleobase radicals play in strand scission has been investigated indirectly using ionizing radiation to generate them. More recently, the reactivity of nucleobase radicals resulting from formal hydrogen atom or hydroxyl radical addition to pyrimidines has been studied by independently generating the reactive intermediates via UV-photolysis of synthetic precursors. This approach has provided control over where the reactive intermediates are produced within biopolymers and facilitated studying their reactivity. The contributions to our understanding of pyrimidine nucleobase radical reactivity by this approach are summarized.

  8. A spectroscopic study of the molecular interactions of harmane with pyrimidine and other diazines.

    Science.gov (United States)

    Muñoz, M A; Guardado, P; Galán, M; Carmona, C; Balón, M

    2000-01-17

    FTIR, UV-vis, steady state and time-resolved fluorescence measurements show that harmane (1-methyl-9H-pyrido/3,4-b/indole) interacts with pyrimidine and its isomers pyrazine and pyridazine in its ground and lowest singlet states. The mechanisms of interaction are dependent on both the structure of the diazine and the nature of the solvent. Thus, in a low polar solvent such as toluene, harmane forms ground state 1:1 hydrogen-bonded complexes with all the diazines. These complexes quench the fluorescence of harmane and diminish its fluorescence lifetime. Conversely, in buffered (pH 8.7) aqueous solutions, pyrimidine behaves differently from the other diazines. Thus, whereas pyrimidine only interacts with harmane in its ground state, pyrazine and pyridazine also interact in the excited state. The harmane-pyrimidine ground state interaction is an entropic controlled process. Therefore, we propose the formation of pi-pi stacked 1:1 complexes between these substrates. Association constants for the different types of complexes and quenching parameters are reported.

  9. Photoreactivation of ultraviolet radiation-induced pyrimidine dimers in neonatal BALB/c mouse skin

    International Nuclear Information System (INIS)

    Ananthaswamy, H.N.; Fisher, M.S.

    1981-01-01

    The numbers of ultraviolet light (uv)-induced pyrimidine dimers in the DNA of neonatal BALB/c mouse skin were measured by assessing the sensitivity of the DNA to Micrococcus luteus uv endonuclease. Irradiation of neonatal BALB/c mice with FS40 sunlamps caused a dose-dependent induction of endonuclease-sensitive sites (pyrimidine dimers) in DNA extracted from back skin. Exposure of these uv-irradiated neonatal mice to photoreactivating (PR) light (cool white fluorescent lamp and incandescent lamp) caused a reduction in the number of pyrimidine dimers in the DNA, as revealed by a shift in low-molecular-weight DNA to high-molecular-weight DNA. In contrast, DNA profiles of the skin of either uv-irradiated mice or uv-irradiated mice kept in the dark for the same duration as those exposed to PR light did not show a loss of uv-induced endonuclease-sensitive sites. Furthermore, reversing the order of treatment, i.e., administering PR light first and then uv, did not produce a reduction in pyrimidine dimers. These results demonstrate that PR or uv-induced pyrimidine dimers occurs in neonatal BALB/c mouse skin. The optimal wavelength range for in vivo PR appears to be in the visible region of the spectrum (greater than 400 nm). Although dimer formation could be detected in both dermis and epidermis, PR occurred only in the dermis. Furthermore, the PR phenomenon could not be detected in the skin of adult mice from the same inbred strain

  10. A second pathway to degrade pyrimidine nucleic acid precursors in eukaryotes

    DEFF Research Database (Denmark)

    Andersen, Gorm; Bjornberg, Olof; Polakova, Silvia

    2008-01-01

    Pyrimidine bases are the central precursors for RNA and DNA, and their intracellular pools are determined by de novo, salvage and catabolic pathways. In eukaryotes, degradation of uracil has been believed to proceed only via the reduction to dihydrouracil. Using a yeast model, Saccharomyces kluyv...... of the eukaryotic or prokaryotic genes involved in pyrimidine degradation described to date.......Pyrimidine bases are the central precursors for RNA and DNA, and their intracellular pools are determined by de novo, salvage and catabolic pathways. In eukaryotes, degradation of uracil has been believed to proceed only via the reduction to dihydrouracil. Using a yeast model, Saccharomyces......, respectively. The gene products of URC1 and URC4 are highly conserved proteins with so far unknown functions and they are present in a variety of prokaryotes and fungi. In bacteria and in some fungi, URC1 and URC4 are linked on the genome together with the gene for uracil phosphoribosyltransferase (URC6). Urc1...

  11. Developments in platinum anticancer drugs

    Science.gov (United States)

    Tylkowski, Bartosz; Jastrząb, Renata; Odani, Akira

    2018-01-01

    Platinum compounds represent one of the great success stories of metals in medicine. Following the unexpected discovery of the anticancer activity of cisplatin (Fig. 1) in 1965 by Prof. Rosenberg [1], a large number of its variants have been prepared and tested for their ability to kill cancer cells and inhibit tumor growth. Although cisplatin has been in use for over four decades, new and more effective platinum-based therapeutics are finally on the horizon. A wide introduction to anticancer studies is given by the authors of the previous chapter. This chapter aims at providing the readers with a comprehensive and in-depth understanding of recent developments of platinum anticancer drugs and to review the state of the art. The chapter is divided into two parts. In the first part we present a historical aspect of platinum and its complexes, while in the second part we give an overview of developments in the field of platinum anticancer agents.

  12. Heteroaromatization with 4-Hydroxycoumarin Part II: Synthesis of Some New Pyrano[2,3-d]pyrimidines, [1,2,4]triazolo[1,5-c]pyrimidines and Pyrimido[1,6-b]-[1,2,4]triazine Derivatives

    Directory of Open Access Journals (Sweden)

    A. H. Bedair

    2001-05-01

    Full Text Available A variety of novel [1,2,4]triazolo[1,5-c]pyrimidine-13-ones (4a-f and (5b-d could be obtained via reaction of 9-amino-7-(4’-chlorophenyl-8,9-dihydro-8-imino-6H,7H-[1]benzopyrano[3`,4`:5,6]pyrano[2,3-d]pyrimidine-6-one (3 with a variety of reagents. Pyrano[2,3-d]pyrimidine-6-ones 5a, 8a-c and pyrimido[1,6-b][1,2,4]-triazine-3,14-dione (6 were also prepared. The antimicrobial activity of some of the synthesized compounds was tested.

  13. TP53 status and taxane-platinum versus platinum-based therapy in ovarian cancer patients: A non-randomized retrospective study

    Directory of Open Access Journals (Sweden)

    Markowska Janina

    2008-01-01

    Full Text Available Abstract Background Taxane-platinum therapy (TP has replaced platinum-based therapy (PC or PAC, DNA damaging chemotherapy in the postoperative treatment of ovarian cancer patients; however, it is not always effective. TP53 protein plays a differential role in response to DNA-damaging agents and taxanes. We sought to define profiles of patients who benefit the most from TP and also of those who can be treated with PC. Methods We compared the effectiveness of PC/PAC (n = 253 and TP (n = 199 with respect to tumor TP53 accumulation in ovarian cancer patients with FIGO stage IIB-IV disease; this was a non-randomized retrospective study. Immunohistochemical analysis was performed on 452 archival tumors; univariate and multivariate analysis by the Cox's and logistic regression models was performed in all patients and in subgroups with [TP53(+] and without TP53 accumulation [TP53(-]. Results The advantage of taxane-platinum therapy over platinum-based therapy was seen in the TP53(+, and not in the TP53(- group. In the TP53(+ group taxane-platinum therapy enhanced the probability of complete remission (p = .018, platinum sensitivity (p = .014, platinum highly sensitive response (p = .038 and longer survival (OS, p = .008. Poor tumor differentiation diminished the advantage from taxane-platinum therapy in the TP53(+ group. In the TP53(- group PC/PAC was at least equally efficient as taxane-platinum therapy and it enhanced the chance of platinum highly sensitive response (p = .010. However, in the TP53(- group taxane-platinum therapy possibly diminished the risk of death in patients over 53 yrs (p = .077. Among factors that positively interacted with taxane-platinum therapy in some analyses were endometrioid and clear cell type, FIGO III stage, bulky residual tumor, more advanced age of patient and moderate tumor differentiation. Conclusion Our results suggest that taxane-platinum therapy is particularly justified in patients with TP53(+ tumors or older

  14. Novel non-platinum metal catalyst material

    DEFF Research Database (Denmark)

    2014-01-01

    The present invention relates to a novel non-platinum metal catalyst material for use in low temperature fuel cells and electrolysers and to fuel cells and electrolysers comprising the novel non-platinum metal catalyst material. The present invention also relates to a novel method for synthesizing...... the novel non-platinum metal catalyst material....

  15. Efficient fluorescent red, green, and blue organic light-emitting devices with a blue host of spirobifluorene derivative

    Energy Technology Data Exchange (ETDEWEB)

    Lee, R.-H. [Department of Chemical and Material Engineering, National Yunlin University of Science and Technology, Yunlin 640, Taiwan (China)], E-mail: lerongho@yuntech.edu.tw; Huang, Y.-W.; Wang, Y.-Y. [Department of Chemical and Material Engineering, National Yunlin University of Science and Technology, Yunlin 640, Taiwan (China); Chang, H.-Y. [EChem Hightech CO., LTD, Hsin-Chu Industrial Park, Hu-Kou, Hsin-Chu, Taiwan (China)

    2008-06-02

    Efficient fluorescent blue, green, and red (RGB) organic light-emitting devices (OLEDs) were fabricated using a blue host material of pyrimidine-containing spirobifluorene derivative 2,7-bis[2-(4-tert-butylphenyl)pyrimidine-5-yl]-9,9'-spirobifluorene (TBPSF) doped with blue dye perylene, green dye 10-(2-benzothiazolyl)-1,1,7,7-tetramethyl-2,3,6,7-tetrahydro-1H,5H, 11H-benzo[l] pyrano[6,7,8-ij] quinolizin-11-one (C545T), and red dye 4-(dicyanomethylene)-2-t-butyl-6-(1,1,7,7-tetramethyljulolidyl-9-enyl) -4H-pyran (DCJTB), respectively. The brightness and current efficiency of the perylene doped blue device reached 10117 cd/m{sup 2} and 2.97 cd/A. Green emission of the C545T doped device reached 8500 cd/m{sup 2} and 13.0 cd/A. Red emission of the DCJTB doped device can be as high as 9000 cd/m{sup 2} and 2.0 cd/A, respectively. High color purity of the blue (Commission Internationale de L'Eclairage (CIE{sub x,y}) coordinates (CIE, x = 0.27, y = 0.24)), green (CIE, x = 0.19, y = 0.63) and red (CIE, x = 0.62, y = 0.37) emissions were achieved for RGB dyes doped TBPSF OLEDs. High brightness, large current efficiency, and good color purity of TBPSF-based RGB OLEDs were obtained by the configuration optimization device, such as inserting the hole and electron-injection materials, and suitable dopant content and light emitting layer thickness.

  16. Effect of substituent structure on pyrimidine electrophilic substitution

    CSIR Research Space (South Africa)

    Van der Westhuyzen, CW

    2007-01-01

    Full Text Available In an investigation into the electrophilic nitrosation reactions of a series of 4,6-disubstituted pyrimidine derivatives, a subtle interplay between the electronic nature of the C-4 and C-6 substituents and reactivity was found where these were...

  17. Tetraoxane-pyrimidine nitrile hybrids as dual stage antimalarials.

    Science.gov (United States)

    Oliveira, Rudi; Guedes, Rita C; Meireles, Patrícia; Albuquerque, Inês S; Gonçalves, Lídia M; Pires, Elisabete; Bronze, Maria Rosário; Gut, Jiri; Rosenthal, Philip J; Prudêncio, Miguel; Moreira, Rui; O'Neill, Paul M; Lopes, Francisca

    2014-06-12

    The use of artemisinin or other endoperoxides in combination with other drugs is a strategy to prevent development of resistant strains of Plasmodium parasites. Our previous work demonstrated that hybrid compounds, comprising endoperoxides and vinyl sulfones, were capable of high activity profiles comparable to artemisinin and chloroquine while acting through two distinct mechanisms of action: oxidative stress and falcipain inhibition. In this study, we adapted this approach to a novel class of falcipain inhibitors: peptidomimetic pyrimidine nitriles. Pyrimidine tetraoxane hybrids displayed potent nanomolar activity against three strains of Plasmodium falciparum and falcipain-2, combined with low cytotoxicity. In vivo, a decrease in parasitemia and an increase in survival of mice infected with Plasmodium berghei was observed when compared to control. All tested compounds combined good blood stage activity with significant effects on liver stage parasitemia, a most welcome feature for any new class of antimalarial drug.

  18. Isotope exchange reactions of the hydrogen H-5 of selected pyrimidine derivatives and the preparation of tritium-labeled pyrimidines

    Czech Academy of Sciences Publication Activity Database

    Dračínský, Martin; Jansa, Petr; Elbert, Tomáš

    2011-01-01

    Roč. 76, č. 12 (2011), s. 1567-1577 ISSN 0010-0765 R&D Projects: GA AV ČR KJB400550903; GA MŠk 1M0508 Institutional research plan: CEZ:AV0Z40550506 Keywords : isotopic labeling * NMR spectroscopy * nucleobases * pyrimidines Subject RIV: CC - Organic Chemistry Impact factor: 1.283, year: 2011

  19. UV light-induced cyclobutane pyrimidine dimers are mutagenic in mammalian cells

    International Nuclear Information System (INIS)

    Protic-Sabljic, M.; Tuteja, N.; Munson, P.J.; Hauser, J.; Kraemer, K.H.; Dixon, K.

    1986-01-01

    We used a simian virus 40-based shuttle vector plasmid, pZ189, to determine the role of pyrimidine cyclobutane dimers in UV light-induced mutagenesis in monkey cells. The vector DNA was UV irradiated and then introduced into monkey cells by transfection. After replication, vector DNA was recovered from the cells and tested for mutations in its supF suppressor tRNA marker gene by transformation of Escherichia coli carrying a nonsense mutation in the beta-galactosidase gene. When the irradiated vector was treated with E. coli photolyase prior to transfection, pyrimidine cyclobutane dimers were removed selectively. Removal of approximately 90% of the pyrimidine cyclobutane dimers increased the biological activity of the vector by 75% and reduced its mutation frequency by 80%. Sequence analysis of 72 mutants recovered indicated that there were significantly fewer tandem double-base changes and G X C----A X T transitions (particularly at CC sites) after photoreactivation of the DNA. UV-induced photoproducts remained (although at greatly reduced levels) at all pyr-pyr sites after photoreactivation, but there was a relative increase in photoproducts at CC and TC sites and a relative decrease at TT and CT sites, presumably due to a persistence of (6-4) photoproducts at some CC and TC sites. These observations are consistent with the fact that mutations were found after photoreactivation at many sites at which only cyclobutane dimers would be expected to occur. From these results we conclude that UV-induced pyrimidine cyclobutane dimers are mutagenic in DNA replicated in monkey cells

  20. Photoreactivation of UV-induced pyrimidine dimers and erythema in the marsupial Monodelphis domestica

    International Nuclear Information System (INIS)

    Ley, R.D.

    1985-01-01

    Post-UV treatment of the gray, short-tailed opossum Monodelphis domestica with photoreactivating light (320-400 nm) suppressed the appearance of UV-induced erythema as evidenced by an increase in the dose of UV required to elicit an erythemal response. Pre-UV exposure to photoreactivating light had no effect on the UV induction of erythema. The dose-response for the photoreversal of pyrimidine dimers in epidermal DNA of M. domestica was similar to that for the photoreactivation of erythema induction. These data not only support the notion that DNA is the primary chromophore involved in the induction of erythema but also identify pyrimidine dimers as the major DNA change responsible for its induction. These results also identify M. domestica as a useful whole-animal system with which to determine the role of pyrimidine dimers in other photobiological responses of mammalian skin

  1. Novel platinum black electroplating technique improving mechanical stability.

    Science.gov (United States)

    Kim, Raeyoung; Nam, Yoonkey

    2013-01-01

    Platinum black microelectrodes are widely used as an effective neural signal recording sensor. The simple fabrication process, high quality signal recording and proper biocompatibility are the main advantages of platinum black microelectrodes. When microelectrodes are exposed to actual biological system, various physical stimuli are applied. However, the porous structure of platinum black is vulnerable to external stimuli and destroyed easily. The impedance level of the microelectrode increases when the microelectrodes are damaged resulting in decreased recording performance. In this study, we developed mechanically stable platinum black microelectrodes by adding polydopamine. The polydopamine layer was added between the platinum black structures by electrodeposition method. The initial impedance level of platinum black only microelectrodes and polydopamine added microelectrodes were similar but after applying ultrasonication the impedance value dramatically increased for platinum black only microelectrodes, whereas polydopamine added microelectrodes showed little increase which were nearly retained initial values. Polydopamine added platinum black microelectrodes are expected to extend the availability as neural sensors.

  2. Synthesis of some pyridine and pyrimidine derivatives via Michael-Addition

    International Nuclear Information System (INIS)

    El-Baih, Fatma E.M.; Al-Rasheed, Hessa H.; Al-Hazimi, Hassan M.

    2006-01-01

    Synthesis of pyridine and pyrimidine analogues 4 and 6-9 were achieved by Michael-addition of compounds containing either active methylene groups like, malononitrile , ethyl cyanoacetate and 1-tetralone or compounds containing active hydrogen atoms like, guanidine in the presence of an oxidizing agent and thiourea to 2-arylmethylidine-1-tetralone and 2-arylmethylidine-6-methoxy-1-tetralone (2) (enones). Addition of malononitrile in piperidine at room temperature to 2-amino-3-cyno-naphtho [1, 2-malonoitrile in sodium alkoxide or sodium hydroxide to 2 gave 4. Cyclization of 3a with acetic anhydride in the presence of conc. H2sO4 gave the naphtha-pyrano[2, 3-d]pyrimidin-8-one (5). Condensation of the pyrimidine thione derivatives 9 with chloroacetic acid gave the 3-oxobenzo[h]thiazoladino[2, 3-b]quinazoline derivatives (10), which were reacted through their active methylene groups with aromatic aldehydes to give the arylidine derivatives 11. These compounds were also prepared in one step by reacting 9 with chloroacetic acid and aromatic aldehydes. Condensation of 9 with 3-bromopropanoic acid gave 4-oxo-benzo[h]1, 3-thiazino[2, 3-b]quinazoline derivatives (12). The structures of the prepared compounds were mainly confirmed on the basis of spectroscopic methods. (author)

  3. Ultraviolet Irradiation of Pyrimidine in Interstellar Ice Analogs: Formation and Photo-Stability of Nucleobases

    Science.gov (United States)

    Nuevo, Michel; Milam, Stefanie N.; Sandford, Scott A.; Elsila, Jamie E.; Dworkin, Jason P.

    2010-01-01

    Astrochemistry laboratory experiments recently showed that molecules of prebiotic interest can potentially form in space, as supported by the detection of amino acids in organic residues formed by the UV photolysis of ices simulating interstellar and cometary environments (H2O, CO, CO2, CH3OH, NH3, etc.). Although the presence of amino acids in the interstellar medium (ISM) is still under debate, experiments and the detection of amino acids in meteorites both support a scenario in which prebiotic molecules could be of extraterrestrial origin, before they are delivered to planets by comets, asteroids, and interplanetary dust particles. Nucleobases, the informational subunits of DNA and RNA, have also been detected in meteorites, although they have not yet been observed in the ISM. Thus, these molecules constitute another family of prebiotic compounds that can possibly form via abiotical processes in astrophysical environments. Nucleobases are nitrogen-bearing cyclic aromatic species with various functional groups attached, which are divided into two classes: pyrimidines (uracil, cytosine, and thymine) and purines (adenine and guanine). In this work, we study how UV irradiation affects pyrimidine mixed in interstellar ice analogs (H2O, NH3, CH3OH). In particular, we show that the UV irradiation of H2O:pyrimidine mixtures leads to the production of oxidized compounds including uracil, and show that both uracil and cytosine are formed upon irradiation of H2O:NH3:pyrimidine mixtures. We also study the photostability of pyrimidine and its photoproducts formed during these experiments.

  4. Platinum-group elements

    Science.gov (United States)

    Zientek, Michael L.; Loferski, Patricia J.; Parks, Heather L.; Schulte, Ruth F.; Seal, Robert R.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    The platinum-group elements (PGEs)—platinum, palladium, rhodium, ruthenium, iridium, and osmium—are metals that have similar physical and chemical properties and tend to occur together in nature. PGEs are indispensable to many industrial applications but are mined in only a few places. The availability and accessibility of PGEs could be disrupted by economic, environmental, political, and social events. The United States net import reliance as a percentage of apparent consumption is about 90 percent.PGEs have many industrial applications. They are used in catalytic converters to reduce carbon monoxide, hydrocarbon, and nitrous oxide emissions in automobile exhaust. The chemical industry requires platinum or platinum-rhodium alloys to manufacture nitric oxide, which is the raw material used to manufacture explosives, fertilizers, and nitric acid. In the petrochemical industry, platinum-supported catalysts are needed to refine crude oil and to produce aromatic compounds and high-octane gasoline. Alloys of PGEs are exceptionally hard and durable, making them the best known coating for industrial crucibles used in the manufacture of chemicals and synthetic materials. PGEs are used by the glass manufacturing industry in the production of fiberglass and flat-panel and liquid crystal displays. In the electronics industry, PGEs are used in computer hard disks, hybridized integrated circuits, and multilayer ceramic capacitors.Aside from their industrial applications, PGEs are used in such other fields as health, consumer goods, and finance. Platinum, for example, is used in medical implants, such as pacemakers, and PGEs are used in cancer-fighting drugs. Platinum alloys are an ideal choice for jewelry because of their white color, strength, and resistance to tarnish. Platinum, palladium, and rhodium in the form of coins and bars are also used as investment commodities, and various financial instruments based on the value of these PGEs are traded on major exchanges

  5. How study patients who receive fluo pyrimidines to prevent ischemic events

    International Nuclear Information System (INIS)

    Saldombide, L.

    2010-01-01

    Introduction: Ischemic heart disease is the main cause of death in Uruguay and cancer is the second. The pillar of the systemic treatment of colorectal cancer are fluo pyrimidines and cause acute ischemic events in 3-8% of t rated patients. The 5 fluorouracil is the third anticancer drug most used Objective: Due to the high incidence of the two diseases and the risk of death caused by the ischemic treatment complications, the literature is analyzed to define how to study patients who receive fluo pyrimidines as a medium of preventing the same. Development: fluo pyrimidines cardio-toxicity can occur by myocardial toxicity, vasospasm, dihydropyrimidine dehydrogenase deficiency, autoimmune phenomena, platelet hyper aggregability, etc. The clinic is varied and underestimated: angina, abnormal ST silent and reversible, arrhythmias, heart failure, hypertension and heart failure. It is the most common complication with continuous infusion of 5 Fu and its equivalent capecitabine with bolus f lou pyrimidines. It is common that ischemic heart disease prioritises the risk increase of complications, but their absence does not exist. Without ischemic heart disease it is difficult to prevent ischemic events, however proposes that the older higher risk. Results: No uniform guidelines is advised: detailed history, determine if risk factors such as smoking, hypertension, diabetes and dyslipidemia and They are present electrocardiogram and cardiac evaluation. Warn the patient about angina l pain as early symptom and monitor symptoms during chemotherapy including cardio-vascular hypotension. Discontinue the medication and perform classic anti-angina l symptoms and / or signs of ischemia. Not reintroduce unless it is the only therapeutic option, since mortality may exceed

  6. Synthesis of pyrimidine carboxamide derivatives catalyzed by uranyl

    African Journals Online (AJOL)

    2014-09-02

    (Received September 2, 2014; revised January 1, 2016). ABSTRACT. An efficient and simple method was developed for the synthesis pyrimidine-5-carboxamides using. UO2(NO3)2.6H2O catalyst under conventional and microwave irradiation. The synthesis of dihydropyrimidine using uranyl nitrate had shown many ...

  7. Spin crossover and high spin filtering behavior in Co-Pyridine and Co-Pyrimidine molecules

    Science.gov (United States)

    Wen, Zhongqian; Zhou, Liping; Cheng, Jue-Fei; Li, Shu-Jin; You, Wen-Long; Wang, Xuefeng

    2018-03-01

    We present a theoretical study on a series of cobalt complexes, which are constructed with cobalt atoms and pyridine/pyrimidine rings, using density functional theory. We investigate the structural and electric transport properties of spin crossover (SCO) Co complex with two spin states, namely low-spin configuration [LS] and high-spin configuration [HS]. Energy analyses of the two spin states imply that the SCO Co-Pyridine2 and Co-Pyrimidine2 complexes may display a spin transition process accompanied by a geometric modification driven by external stimuli. A nearly perfect spin filtering effect is observed in the Co-Pyrimidine2 complex with [HS] state. In addition, we also discover the contact-dependent transmission properties of Co-Pyridine2. These findings indicate that SCO Co complexes are promising materials for molecular spintronic devices.

  8. Synthesis and fluorescence of new 3-biphenylpyrrolo[1,2-c]pyrimidines

    Directory of Open Access Journals (Sweden)

    Marian-Laurentiu Tatu

    2017-07-01

    Full Text Available New pyrrolo[1,2-c]pyrimidines derivates having a biphenyl moiety at position 3 have been synthesized by 1,3-dipolar cycloaddition of their corresponding N-ylides with activated alkynes. FTIR, 1H and 13C NMR spectroscopy and elemental analysis have been used to characterize the structures of the new nine pyrrolo[1,2-c]pyrimidine derivates. Absorption and fluorescence spectra have been recorded. The appropriate solvent for the photoluminescence properties of the studied compounds has been found to be chloroform:acetonitrile mixture (1:1. The main spectral features such as molar extinction coefficients (ε, Stokes shifts, quantum yields using quinine sulphate as standard, fluorescence quenching in the presence of benzoquinone and Stern-Volmer constants have been calculated. The substituent effects on intensity of absorption, maximum absorbance wavelengths and fluorescence parameters have been discussed. The highest quantum yield value was found for ethyl 3-(4-biphenylyl-7-(3,4-dimethoxybenzoylpyrrolo[1,2-c]pyrimidine-5-carboxylate (0.55. The obtained results suggest that the studied compounds are promising candidates for future study in order to evaluate their use in practical applications in fluorescent chemical sensors.

  9. Intermediate energy cross sections for electron-impact vibrational-excitation of pyrimidine

    Energy Technology Data Exchange (ETDEWEB)

    Jones, D. B. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Ellis-Gibbings, L.; García, G. [Instituto de Física Fundamental, CSIC, Serrano 113-bis, 28006 Madrid (Spain); Nixon, K. L. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); School of Biology, Chemistry and Forensic Science, University of Wolverhampton, Wolverhampton WV1 1LY (United Kingdom); Lopes, M. C. A. [Departamento de Física, Universidade Federal de Juiz de Fora, 36036-330 Juiz de Fora, Minas Gerais (Brazil); Brunger, M. J., E-mail: Michael.Brunger@flinders.edu.au [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, SA 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2015-09-07

    We report differential cross sections (DCSs) and integral cross sections (ICSs) for electron-impact vibrational-excitation of pyrimidine, at incident electron energies in the range 15–50 eV. The scattered electron angular range for the DCS measurements was 15°–90°. The measurements at the DCS-level are the first to be reported for vibrational-excitation in pyrimidine via electron impact, while for the ICS we extend the results from the only previous condensed-phase study [P. L. Levesque, M. Michaud, and L. Sanche, J. Chem. Phys. 122, 094701 (2005)], for electron energies ⩽12 eV, to higher energies. Interestingly, the trend in the magnitude of the lower energy condensed-phase ICSs is much smaller when compared to the corresponding gas phase results. As there is no evidence for the existence of any shape-resonances, in the available pyrimidine total cross sections [Baek et al., Phys. Rev. A 88, 032702 (2013); Fuss et al., ibid. 88, 042702 (2013)], between 10 and 20 eV, this mismatch in absolute magnitude between the condensed-phase and gas-phase ICSs might be indicative for collective-behaviour effects in the condensed-phase results.

  10. Activation analysis for platinum in gold and metals of the platinum group through 199Au

    International Nuclear Information System (INIS)

    Foerster, H.

    1976-01-01

    Platinum was determined in gold and in metals of the platinum group through 199 Au by activation analysis. The matrix was separated at the end of irradiation before the daughter nuclide was formed. Gold was separated by extraction with MIBK from 1

  11. Low platinum catalyst and method of preparation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Di-Jia; Chong, Lina

    2017-11-21

    A low platinum catalyst and method for making same. The catalyst comprises platinum-transition metal bimetallic alloy microcrystallites over a transition metal-nitrogen-carbon composite. A method of making a catalyst comprises preparation of transition metal organic frameworks, infusion of platinum, thermal treatment, and reduction to form the microcrystallites and composite.

  12. Functional and genetic evidence that nucleoside transport is highly conserved in Leishmania species: Implications for pyrimidine-based chemotherapy

    Directory of Open Access Journals (Sweden)

    Khalid J.H. Alzahrani

    2017-08-01

    Full Text Available Leishmania pyrimidine salvage is replete with opportunities for therapeutic intervention with enzyme inhibitors or antimetabolites. Their uptake into cells depends upon specific transporters; therefore it is essential to establish whether various Leishmania species possess similar pyrimidine transporters capable of drug uptake. Here, we report a comprehensive characterization of pyrimidine transport in L. major and L. mexicana. In both species, two transporters for uridine/adenosine were detected, one of which also transported uracil and the antimetabolites 5-fluoruracil (5-FU and 5F,2′deoxyuridine (5F,2′dUrd, and was designated uridine-uracil transporter 1 (UUT1; the other transporter mediated uptake of adenosine, uridine, 5F,2′dUrd and thymidine and was designated Nucleoside Transporter 1 (NT1. To verify the reported L. donovani model of two NT1-like genes encoding uridine/adenosine transporters, and an NT2 gene encoding an inosine transporter, we cloned the corresponding L. major and L. mexicana genes, expressing each in T. brucei. Consistent with the L. donovani reports, the NT1-like genes of either species mediated the adenosine-sensitive uptake of [3H]-uridine but not of [3H]-inosine. Conversely, the NT2-like genes mediated uptake of [3H]-inosine but not [3H]-uridine. Among pyrimidine antimetabolites tested, 5-FU and 5F,2′dUrd were the most effective antileishmanials; resistance to both analogs was induced in L. major and L. mexicana. In each case it was found that the resistant cells had lost the transport capacity for the inducing drug. Metabolomics analysis found that the mechanism of action of 5-FU and 5F-2′dUrd was similar in both Leishmania species, with major changes in deoxynucleotide metabolism. We conclude that the pyrimidine salvage system is highly conserved in Leishmania species - essential information for the development of pyrimidine-based chemotherapy. Keywords: Leishmania, Pyrimidine metabolism, Uracil

  13. Redeposition of electrochemically dissolved platinum as nanoparticles on carbon

    DEFF Research Database (Denmark)

    Norgaard, C. F.; Stamatin, S. N.; Skou, E. M.

    2014-01-01

    communication reports a simple chemical method for reprecipitating platinum as nanoparticles of reasonable particle size on a carbon substrate without intermediary separation and handling of solid platinum salt. After electrochemical dissolution, platinum was reprecipitated using a polyol based method. Platinum...

  14. Strategies for the fabrication of porous platinum electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Kloke, Arne; Stetten, Felix von; Kerzenmacher, Sven [Laboratory for MEMS Applications, Department of Microsystems Engineering-IMTEK, University of Freiburg, Freiburg (Germany); Zengerle, Roland [Laboratory for MEMS Applications, Department of Microsystems Engineering-IMTEK, University of Freiburg, Freiburg (Germany); BIOSS Centre for Biological Signalling Studies, Albert-Ludwigs-Universitaet Freiburg (Germany)

    2011-11-16

    Porous platinum is of high technological importance due to its various applications in fuel cells, sensors, stimulation electrodes, mechanical actuators and catalysis in general. Based on a discussion of the general principles behind the reduction of platinum salts and corresponding deposition processes this article discusses techniques available for platinum electrode fabrication. The numerous, different strategies available to fabricate platinum electrodes are reviewed and discussed in the context of their tuning parameters, strengths and weaknesses. These strategies comprise bottom-up approaches as well as top-down approaches. In bottom-up approaches nanoparticles are synthesized in a first step by chemical, photochemical or sonochemical means followed by an electrode formation step by e.g. thin film technology or network formation to create a contiguous and conducting solid electrode structure. In top-down approaches fabrication starts with an already conductive electrode substrate. Corresponding strategies enable the fabrication of substrate-based electrodes by e.g. electrodeposition or the fabrication of self-supporting electrodes by dealloying. As a further top-down strategy, this review describes methods to decorate porous metals other than platinum with a surface layer of platinum. This way, fabrication methods not performable with platinum can be applied to the fabrication of platinum electrodes with the special benefit of low platinum consumption. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  15. Platinum recycling in the United States in 1998

    Science.gov (United States)

    Hilliard, Henry E.

    2001-01-01

    In the United States, catalytic converters are the major source of secondary platinum for recycling. Other sources of platinum scrap include reforming and chemical process catalysts. The glass industry is a small but significant source of platinum scrap. In North America, it has been estimated that in 1998 more than 20,000 kilograms per year of platinum-group metals from automobile catalysts were available for recycling. In 1998, an estimated 7,690 kilograms of platinum were recycled in the United States. U.S. recycling efficiency was calculated to have been 76 percent in 1998; the recycling rate was estimated at 16 percent.

  16. Synthesis and comparing the antibacterial activities of pyrimidine ...

    Indian Academy of Sciences (India)

    heterocyclic ring substituted in pyrimidine derivatives have moderate inhibition against ... moved by boiling in presence of catalyst and hydrazine .... by Biginelli reaction. The structures of the synthesized compounds were confirmed by IR, 1H and 13C NMR,. GC-MS and CHN analysis. Formation of 2a was con- firmed by the ...

  17. Intramolecular inverse electron demand Diels-Alder reactions of pyrimidines

    NARCIS (Netherlands)

    Frissen, A.E.

    1990-01-01

    This thesis deals with the intramolecular inverse electron demand Diels-Alder reaction of pyrimidines. The main objective of the study was to investigate the synthetic applicability of this reaction and to get more insight in the electronic and steric effects which determine the reactivity

  18. The photochemistry of pyrimidine in realistic astrophysical ices and the production of nucleobases

    International Nuclear Information System (INIS)

    Nuevo, Michel; Materese, Christopher K.; Sandford, Scott A.

    2014-01-01

    Nucleobases, together with deoxyribose/ribose and phosphoric acid, are the building blocks of DNA and RNA for all known life. The presence of nucleobase-like compounds in carbonaceous chondrites delivered to the Earth raises the question of an extraterrestrial origin for the molecules that triggered life on our planet. Whether these molecules are formed in interstellar/protostellar environments, in small parent bodies in the solar system, or both, is currently unclear. Recent experiments show that the UV irradiation of pyrimidine (C 4 H 4 N 2 ) in H 2 O-rich ice mixtures that contain NH 3 , CH 3 OH, or CH 4 leads to the formation of the pyrimidine-based nucleobases uracil, cytosine, and thymine. In this work, we discuss the low-temperature UV irradiation of pyrimidine in realistic astrophysical ice mixtures containing H 2 O, CH 3 OH, and NH 3 , with or without CH 4 , to search for the production of nucleobases and other prebiotic compounds. These experiments show the presence of uracil, urea, glycerol, hexamethylenetetramine, small amino acids, and small carboxylic acids in all samples. Cytosine was only found in one sample produced from ices irradiated with a higher UV dose, while thymine was not found in any sample, even after irradiation with a higher UV dose. Results are discussed to evaluate the role of the photochemistry of pyrimidine in the inventory of organic molecules detected in meteorites and their astrophysical/astrobiological implications.

  19. Simple approach to thieno[3,2-d]pyrimidines as new scaffolds of antimicrobial activities

    Directory of Open Access Journals (Sweden)

    Hafez Hend N.

    2016-09-01

    Full Text Available 6ʹ-(4-Chlorophenyl-spiro[cyclohexane-1,2ʹ-thieno[3,2-d][1,3] oxazin]-4ʹ(1ʹH-one (1 was synthesized and used as a starting material for the synthesis of a novel series of spiro compounds having biologically active sulfonamide 2a-e and 3ʹ-(4-acetylphenyl-6ʹ- (4-chlorophenyl-1ʹH-spiro[cyclohexane-1,2ʹ-thieno[3,2-d] pyrimidine-4ʹ(3ʹH-one (3. Compound 2a was used as a key intermediate for the synthesis of sulfonyl carbothioamide derivatives 4a-c. Also, compound 3 was used as an intermediate for the synthesis of 3ʹH-spiro[cyclohexane-1,2ʹ-thieno[3,2-d]pyrimidin]-3ʹ-yl] phenyl}-2-imino-4-(substituted phenyl and/or thienyl-1,2-dihydropyridine- 3-carbonitrile derivatives 5a-e, 3ʹH-spiro[cyclohexane- 1,2ʹ- thieno[3,2-d]pyrimidin]-3ʹ-yl]phenyl}-2-oxo-4-(substituted phenyl and/or thienyl-1,2-dihydropyridine-3-carbonitrile derivatives 6a-e, and 4-[(2Z-3-substituted-arylprop-2-enoyl] phenyl-1ʹH-spiro[cyclohexane-1,2ʹ-thieno[3,2-d]pyrimidine derivatives 7a-e. Cyclocondensation of 7a-e with hydrazine hydrate produced 6ʹ-(4-chlorophenyl-3ʹ-[4-(5-substituted aryl-4,5-dihydro- 1H-pyrazol-3-ylphenyl]-1ʹH-spiro[cyclohexane-1,2ʹ-thieno- [3,2-d]pyrimidin]-4ʹ(3ʹH-ones 8a-e but with hydroxylamine hydrochloride afforded the corresponding isoxazoline derivatives 9a-e. Also, cyclocondensation by thiourea afforded 2-thioxo-1,2- dihydropyrimidin-4-yl-phenyl-spiro-{cyclohexanethieno[3,2-d] pyrimidin}-4-one derivatives 10a-e. The new compounds were investigated for antimicrobial activity. Compounds 2c, 8b,c, 9b and 10b were the most potent ones against both Gram-negative and Gram-positive bacteria. Compound 8c exhibited higher antifungal activity towards the examined fungi with MIC of 1-2 μmol mL-1 compared to ketoconazole (MIC 2-3 μmol mL-1 .

  20. Flow Injection Analysis with Electrochemical Detection for Rapid Identification of Platinum-Based Cytostatics and Platinum Chlorides in Water

    Directory of Open Access Journals (Sweden)

    Marketa Kominkova

    2014-02-01

    Full Text Available Platinum-based cytostatics, such as cisplatin, carboplatin or oxaliplatin are widely used agents in the treatment of various types of tumors. Large amounts of these drugs are excreted through the urine of patients into wastewaters in unmetabolised forms. This phenomenon leads to increased amounts of platinum ions in the water environment. The impacts of these pollutants on the water ecosystem are not sufficiently investigated as well as their content in water sources. In order to facilitate the detection of various types of platinum, we have developed a new, rapid, screening flow injection analysis method with electrochemical detection (FIA-ED. Our method, based on monitoring of the changes in electrochemical behavior of analytes, maintained by various pH buffers (Britton-Robinson and phosphate buffer and potential changes (1,000, 1,100 and 1,200 mV offers rapid and cheap selective determination of platinum-based cytostatics and platinum chlorides, which can also be present as contaminants in water environments.

  1. The effects of thermal-neutron irradiation on platinum and dilute platinum-gold alloys

    International Nuclear Information System (INIS)

    Piani, C.S.B.

    1978-12-01

    The effect of varying defect concentrations on the recovery spectrum of thermal-neutron-irradiated pure platinum after isochronal anneals was investigated. The dose-independence of substages I(A), I(B) and I(C), and the dose dependence of substage I(D) and I(E), were observed to be in agreement with electron-irradiated studies. The 120 K substage in pure platinum was shown not to be due to interstitial-interstitial reactions, but could possibly be accounted for in terms of detrapping of interstitials from impurities or intrinsic immobile defects. The 360 K stage was shown to shift and was suppressed with increasing defect concentration. The possible conversion of the crowdion to a dumbbell near 160 K in Stage ll in platinum, as predicted by the two-interstitial model, was investigated by consideration of the initial slopes of the production curves between 80 K and 300 K. A minimum in these slopes was observed near 160 K and could be interpreted as due to the conversion of the highly mobile crowdion to an immobile dumbbell at this temperature. The influence of varying gold concentrations on the recovery spectrum of platinum was investigated in dilute platinum-gold alloys. The characteristics of several additional substages in Stage ll, due to the gold alloying were comparable to the results of electron-irradiation experiments. The observations made with regard to the impurity (gold) dependence of these substages could be interpreted in terms of the concentrations of the interstitials, vacancies and impurities present in the material. The interpretation of these substages was found to be consistent, if the recovery spectrum was investigated as a function of defect concentration [af

  2. Discovery of pyrazolo[1,5-a]pyrimidine-based CHK1 inhibitors: A template-based approach-Part 2

    Energy Technology Data Exchange (ETDEWEB)

    Labroli, Marc; Paruch, Kamil; Dwyer, Michael P.; Alvarez, Carmen; Keertikar, Kartik; Poker, Cory; Rossman, Randall; Duca, Jose S.; Fischmann, Thierry O.; Madison, Vincent; Parry, David; Davis, Nicole; Seghezzi, Wolfgang; Wiswell, Derek; Guzi, Timothy J. [Merck

    2013-11-20

    Previous efforts by our group have established pyrazolo[1,5-a]pyrimidine as a viable core for the development of potent and selective CDK inhibitors. As part of an effort to utilize the pyrazolo[1,5-a]pyrimidine core as a template for the design and synthesis of potent and selective kinase inhibitors, we focused on a key regulator in the cell cycle progression, CHK1. Continued SAR development of the pyrazolo[1,5-a]pyrimidine core at the C5 and C6 positions, in conjunction with previously disclosed SAR at the C3 and C7 positions, led to the discovery of potent and selective CHK1 inhibitors.

  3. Biological role in the transformation of platinum-group mineral grains

    Science.gov (United States)

    Reith, Frank; Zammit, Carla M.; Shar, Sahar S.; Etschmann, Barbara; Bottrill, Ralph; Southam, Gordon; Ta, Christine; Kilburn, Matthew; Oberthür, Thomas; Ball, Andrew S.; Brugger, Joël

    2016-04-01

    Platinum-group elements are strategically important metals. Finding new deposits is becoming increasingly difficult owing to our limited understanding of the processes that affect their mobility in surface environments. Microorganisms have been shown to promote the mobility of metals around ore deposits. Here we show that microorganisms influence the mobility of platinum-group elements in mineral grains collected from Brazil, Australia and Colombia. Scanning electron microscopy showed biofilms covering the platinum-group mineral grains. The biofilms contained abundant platinum-group element nanoparticles and microcrystalline aggregates, and were dominated by Proteobacteria, many of which were closely related to known metal-resistant species. Some platinum-group mineral grains contained carbon, nitrogen, sulfur, selenium and iodine, suggesting the grains may be biogenic in origin. Molecular analyses show that Brazilian platinum-palladium grains hosted specific bacterial communities, which were different in composition from communities associated with gold grains, or communities in surrounding soils and sediments. Nano-phase metallic platinum accumulated when a metallophillic bacterium was incubated with a percolating platinum-containing medium, suggesting that biofilms can cause the precipitation of mobile platinum complexes. We conclude that biofilms are capable of forming or transforming platinum-group mineral grains, and may play an important role for platinum-group element dispersion and re-concentration in surface environments.

  4. Photoreactivation and excision repair of UV induced pyrimidine dimers in the unicellular cyanobacterium Gloeocapsa alpicola (Synechocystis PCC 6308)

    International Nuclear Information System (INIS)

    O'Brien, P.A.; Houghton, J.A.

    1982-01-01

    The survival curve obtained after UV irradiation of the unicellular cyanobacterium Synechocystis is typical of a DNA repair competent organism. Inhibition of DNA replication, by incubating cells in the dark, increased resistance to the lethal effects of UV at higher fluences. Exposure of irradiated cells to near ultraviolet light (350-500 nm) restored viability to pre-irradiation levels. In order to measure DNA repair activity, techniques have been developed for the chromatographic analysis of pyrimidine dimers in synechocystis. The specificity of this method was established using a haploid strain of Saccharomyces cerevisiae. In accordance with the physiological responses of irradiated cells to photoreactivating light, pyrimidine dimers were not detected after photoreactivation treatment. Incubation of irradiated cells under non-photoreactivating growth conditions for 15h resulted in complete removal of pyrimidine dimers. It is concluded that Synechocystis contains photoreactivation and excision repair systems for the removal of pyrimidine dimers. (author)

  5. Synthesis and Anticancer Activity of Some New Pyrazolo[3,4-d]pyrimidin-4-one Derivatives

    Directory of Open Access Journals (Sweden)

    Khaled R. A. Abdellatif

    2014-03-01

    Full Text Available 3,6-Dimethyl-1-phenyl-1H-pyrazolo[3,4-d][1,3]oxazin-4-one (3 was prepared by hydrolysis of ethyl 5-amino-3-methyl-1-phenyl-1H-pyrazole-4-carboxylate (1 to afford the corresponding carboxylic acid 2, which was reacted with acetic anhydride to give 3. The pyrazolo[3,4-d][1,3]oxazin-4-one 3 was reacted with hydroxylamine hydrochloride, urea, thiourea, thiosemicarbazide, phenylhydrazine and aromatic amines to afford the corresponding pyrazolo[3,4-d]pyrimidin-4-ones 4, 5a,b, 6, 7, 8a–e, respectively. Condensation of pyrazoloxazine derivative 3 with 99% hydrazine hydrate afforded the 5-aminopyrazolo[3,4-d] pyrimidine derivative 9. Coupling of 9 with aromatic aldehydes yielded a series of 3,6-dimethyl-5-(4-substitutedbenzylideneamino-1-phenyl-1,5-dihydropyrazolo[3,4-d]pyrimidin- 4-ones 10a–e. The new compounds were tested for their antitumor activity on the MCF-7 human breast adenocarcinoma cell line. Almost all the tested compounds revealed antitumor activity, especially 3,6-dimethyl-5-(4-nitrobenzylideneamino-1-phenyl-1,5-dihydropyrazolo[3,4-d]pyrimidin-4-one (10e which displayed the most potent inhibitory activity with a half maximal inhibitory concentration (IC50 of 11 µM.

  6. Polyurethane Foams with Pyrimidine Rings

    Directory of Open Access Journals (Sweden)

    Kania Ewelina

    2014-09-01

    Full Text Available Oligoetherols based on pyrimidine ring were obtained upon reaction of barbituric acid with glycidol and alkylene carbonates. These oligoetherols were then used to obtain polyurethane foams in the reaction of oligoetherols with isocyanates and water. The protocol of foam synthesis was optimized by the choice of proper kind of oligoetherol and synthetic composition. The thermal resistance was studied by dynamic and static methods with concomitant monitoring of compressive strength. The polyurethane foams have similar physical properties as the classic ones except their enhanced thermal resistance. They stand long-time heating even at 200°C. Moreover thermal exposition of foams results generally in increase of their compressive strength.

  7. New insights on pyrimidine signalling within the arterial vasculature

    DEFF Research Database (Denmark)

    Haanes, Kristian Agmund; Spray, Stine; Syberg, Susanne

    2016-01-01

    Extracellular pyrimidines activate P2Y receptors on both smooth muscle cells and endothelial cells, leading to vasoconstriction and relaxation respectively. The aim of this study was to utilize P2Y knock-out (KO) mice to determine which P2Y receptor subtype are responsible for the contraction and...

  8. Analysis of pyrimidine dimer content of isolated DNA by nuclease digestion

    International Nuclear Information System (INIS)

    Farland, W.H.; Sutherland, B.M.

    1980-01-01

    Isolated DNA is highly susceptible to degradation by exogenous nucleases. Complete digestion is possible with a number of well-characterized enzymes from a variety of sources. Treatment of DNA with a battery of enzymes including both phosphodiesterase and phosphatase activities yields a mixture of nucleosides and inorganic phosphate (P/sub i/) as a final product. Unlike native DNA, ultraviolet-irradiated DNA is resistant to complete digestion. Setlow et al. demonstrated that the structural changes in the DNA responsible for the nuclease resistance were the formation of cyclobutyl pyrimidine dimers, the major photoproduct in UV-irradiated DNA. Using venom phosphodiesterase, they demonstrated that UV irradiation of DNA affected both the rate and extent of enzymatic hydrolysis. In addition, it was demonstrated that the major nuclease-resistant product of this hydrolysis was an oligonucleotide containing dimerized pyrimidines. Treatment of the DNA to split the dimers, either photochemically or photoenzymatically, rendered the polymer more susceptible to hydrolysis by the phosphodiesterase. The specificity of photoreactivating enzyme for pyrimidine dimers lends support to the role of these structures in conferring nuclease resistance to UV-irradiated DNA. The nuclease resistance of DNA containing dimers has been the basis of several assays for the measurement of these photoproducts. Sutherland and Chamberlin reported the development of a rapid and sensitive assay for dimers in 32 P-labeled DNA

  9. Characterization of electrochemically modified polycrystalline platinum surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Krebs, L.C.; Ishida, Takanobu.

    1991-12-01

    The characterization of electrochemically modified polycrystalline platinum surfaces has been accomplished through the use of four major electrochemical techniques. These were chronoamperometry, chronopotentiommetry, cyclic voltammetry, and linear sweep voltammetry. A systematic study on the under-potential deposition of several transition metals has been performed. The most interesting of these were: Ag, Cu, Cd, and Pb. It was determined, by subjecting the platinum electrode surface to a single potential scan between {minus}0.24 and +1.25 V{sub SCE} while stirring the solution, that the electrocatalytic activity would be regenerated. As a consequence of this study, a much simpler method for producing ultra high purity water from acidic permanganate has been developed. This method results in water that surpasses the water produced by pyrocatalytic distillation. It has also been seen that the wettability of polycrystalline platinum surfaces is greatly dependent on the quantity of oxide present. Oxide-free platinum is hydrophobic and gives a contact angle in the range of 55 to 62 degrees. We have also modified polycrystalline platinum surface with the electrically conducting polymer poly-{rho}-phenylene. This polymer is very stable in dilute sulfuric acid solutions, even under applied oxidative potentials. It is also highly resistant to electrochemical hydrogenation. The wettability of the polymer modified platinum surface is severely dependent on the choice of supporting electrolyte chosen for the electrochemical polymerization. Tetraethylammonium tetrafluoroborate produces a film that is as hydrophobic as Teflon, whereas tetraethylammonium perchlorate produces a film that is more hydrophilic than oxide-free platinum.

  10. Characterization of electrochemically modified polycrystalline platinum surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Krebs, Leonard C. [State Univ. of New York (SUNY), Stony Brook, NY (United States); Ishida, Takanobu [State Univ. of New York (SUNY), Stony Brook, NY (United States)

    1991-12-01

    The characterization of electrochemically modified polycrystalline platinum surfaces has been accomplished through the use of four major electrochemical techniques. These were chronoamperometry, chronopotentiommetry, cyclic voltammetry, and linear sweep voltammetry. A systematic study on the under-potential deposition of several transition metals has been performed. The most interesting of these were: Ag, Cu, Cd, and Pb. It was determined, by subjecting the platinum electrode surface to a single potential scan between -0.24 and +1.25 VSCE while stirring the solution, that the electrocatalytic activity would be regenerated. As a consequence of this study, a much simpler method for producing ultra high purity water from acidic permanganate has been developed. This method results in water that surpasses the water produced by pyrocatalytic distillation. It has also been seen that the wettability of polycrystalline platinum surfaces is greatly dependent on the quantity of oxide present. Oxide-free platinum is hydrophobic and gives a contact angle in the range of 55 to 62 degrees. We have also modified polycrystalline platinum surface with the electrically conducting polymer poly-ρ-phenylene. This polymer is very stable in dilute sulfuric acid solutions, even under applied oxidative potentials. It is also highly resistant to electrochemical hydrogenation. The wettability of the polymer modified platinum surface is severely dependent on the choice of supporting electrolyte chosen for the electrochemical polymerization. Tetraethylammonium tetrafluoroborate produces a film that is as hydrophobic as Teflon, whereas tetraethylammonium perchlorate produces a film that is more hydrophilic than oxide-free platinum.

  11. PET imaging of HSV1-tk mutants with acquired specificity toward pyrimidine- and acycloguanosine-based radiotracers

    Energy Technology Data Exchange (ETDEWEB)

    Likar, Yury; Dobrenkov, Konstantin; Olszewska, Malgorzata; Shenker, Larissa; Hricak, Hedvig; Ponomarev, Vladimir [Memorial Sloan-Kettering Cancer Center, Molecular Imaging Laboratory, Department of Radiology, New York, NY (United States); Cai, Shangde [Memorial Sloan-Kettering Cancer Center, Radiochemistry/Cyclotron Core Facility, New York, NY (United States)

    2009-08-15

    The aim of this study was to create an alternative mutant of the herpes simplex virus type 1 thymidine kinase (HSV1-tk) reporter gene with reduced phosphorylation capacity for acycloguanosine derivatives, but not pyrimidine-based compounds that will allow for successful PET imaging. A new mutant of HSV1-tk reporter gene, suitable for PET imaging using pyrimidine-based radiotracers, was developed. The HSV1-tk mutant contains an arginine-to-glutamine substitution at position 176 (HSV1-R176Qtk) of the nucleoside binding region of the enzyme. The mutant-gene product showed favorable enzymatic characteristics toward pyrimidine-based nucleosides, while exhibiting reduced activity with acycloguanosine derivatives. In order to enhance HSV1-R176Qtk reporter activity with pyrimidine-based radiotracers, we introduced the R176Q substitution into the more active HSV1-sr39tk mutant. U87 human glioma cells transduced with the HSV1-R176Qsr39tk double mutant reporter gene showed high {sup 3}H-FEAU pyrimidine nucleoside and low {sup 3}H-penciclovir acycloguanosine analog uptake in vitro. PET imaging also demonstrated high {sup 18}F-FEAU and low {sup 18}F-FHBG accumulation in HSV1-R176Qsr39tk+ xenografts. The feasibility of imaging two independent nucleoside-specific HSV1-tk mutants in the same animal with PET was demonstrated. Two opposite xenografts expressing the HSV1-R176Qsr39tk reporter gene and the previously described acycloguanosine-specific mutant of HSV1-tk, HSV1-A167Ysr39tk reporter gene, were imaged using a short-lived pyrimidine-based {sup 18}F-FEAU and an acycloguanosine-based {sup 18}F-FHBG radiotracer, respectively, administered on 2 consecutive days. We conclude that in combination with acycloguanosine-specific HSV1-A167Ysr39tk reporter gene, a HSV1-tk mutant containing the R176Q substitution could be used for PET imaging of two different cell populations or concurrent molecular biological processes in the same living subject. (orig.)

  12. Platinum-group elements and gold in base metal sulfides, platinum-group minerals, and Re-Os isotope compositions of the Uitkomst complex, South Africa

    Czech Academy of Sciences Publication Activity Database

    Trubač, Jakub; Ackerman, Lukáš; Gauert, Ch.; Ďurišová, Jana; Hrstka, Tomáš

    2018-01-01

    Roč. 113, č. 2 (2018), s. 439-461 ISSN 0361-0128 R&D Projects: GA ČR GA13-15390S Institutional support: RVO:67985831 Keywords : binary alloys * copper compounds * economic geology * gold * iridium * isotopes * ore deposits * osmium * palladium * platinum * platinum metals * pyrites * Rhenium * rhenium alloys * ruthenium * solid solutions * sulfur compounds * crustal materials * mass-balance calculations * massive sulfides * mineralized zone * monosulfide solid solutions * platinum group elements * platinum group elements (PGEs) * platinum group minerals Subject RIV: DB - Geology ; Mineralogy; AC - Archeology, Anthropology, Ethnology (ARUB-Q) OBOR OECD: Geology; Archaeology (ARUB-Q) Impact factor: 2.519, year: 2016

  13. Nucleotide metabolism in Lactococcus lactis: Salvage pathways of exogenous pyrimidines

    DEFF Research Database (Denmark)

    Martinussen, Jan; Andersen, Paal Skytt; Hammer, Karin

    1994-01-01

    By measuring enzyme activities in crude extracts and studying the effect of toxic analogs (5-fluoropyrimidines) on cell growth, the metabolism of pyrimidines in Lactococcus lactis was analyzed. Pathways by which uracil, uridine, deoxyuridine, cytidine, and deoxycytidine are metabolized in L. lact...

  14. Synthesis of 7-arylethyl-5-arylpyrazolo pyrimidines through an aza ...

    Indian Academy of Sciences (India)

    ZHENG LI

    2017-10-09

    Oct 9, 2017 ... During the past decade, the synthesis of pyrazolo[1,5-a] pyrimidine derivatives ... importance due to pharmaceutical reasons.1,2 For exam- ple, the hypnotic ... In this paper, we report an efficient method for the syn- thesis of ...

  15. Pyrimidine dimers block simian virus 40 replication forks

    International Nuclear Information System (INIS)

    Berger, C.A.; Edenberg, H.J.

    1986-01-01

    UV light produces lesions, predominantly pyrimidine dimers, which inhibit DNA replication in mammalian cells. The mechanism of inhibition is controversial: is synthesis of a daughter strand halted at a lesion while the replication fork moves on and reinitiates downstream, or is fork progression itself blocked for some time at the site of a lesion? We directly addressed this question by using electron microscopy to examine the distances of replication forks from the origin in unirradiated and UV-irradiated simian virus 40 chromosomes. If UV lesions block replication fork progression, the forks should be asymmetrically located in a large fraction of the irradiated molecules; if replication forks move rapidly past lesions, the forks should be symmetrically located. A large fraction of the simian virus 40 replication forks in irradiated molecules were asymmetrically located, demonstrating that UV lesions present at the frequency of pyrimidine dimers block replication forks. As a mechanism for this fork blockage, we propose that polymerization of the leading strand makes a significant contribution to the energetics of fork movement, so any lesion in the template for the leading strand which blocks polymerization should also block fork movement

  16. Total cross sections for positron and electron scattering from pyrimidine

    International Nuclear Information System (INIS)

    Zecca, A; Chiari, L; Trainotti, E; GarcIa, G; Blanco, F; Brunger, M J

    2010-01-01

    In this paper we report original measurements of total cross sections for positron scattering from the important biomolecule pyrimidine. The energy range of these measurements was 0.3-45 eV, while the energy resolution was ∼260 meV. In addition, we report theoretical results, calculated within the independent atom-screened additivity rule (IAM-SCAR) formalism, for the corresponding electron impact total cross sections. In that case the energy range is 1-10 000 eV. Total cross sections are very important input data for codes that seek to simulate charged-particle tracks in matter, as they define the mean-free path between collisions. As the present data and computations are to the best of our knowledge the first total cross sections to be reported for either positron or electron scattering from pyrimidine, they fill an important void in our available knowledge in the literature.

  17. DENV gene of bacteriophage T4 codes for both pyrimidine dimer-DNA glycosylase and apyrimidinic endonuclease activities

    International Nuclear Information System (INIS)

    McMillan, S.; Edenberg, H.J.; Radany, E.H.; Friedberg, R.C.; Friedberg, E.C.

    1981-01-01

    Recent studies have shown that purified preparations of phage T4 UV DNA-incising activity (T4 UV endonuclease or endonuclease V of phase T4) contain a pyrimidine dimer-DNA glycosylase activity that catalyzes hydrolysis of the 5' glycosyl bond of dimerized pyrimidines in UV-irradiated DNA. Such enzyme preparations have also been shown to catalyze the hydrolysis of phosphodiester bonds in UV-irradiated DNA at a neutral pH, presumably reflecting the action of an apurinic/apyrimidinic endonuclease at the apyrimidinic sites created by the pyrimidine dimer-DNA glycosylase. In this study we found that preparations of T4 UV DNA-incising activity contained apurinic/apyrimidinic endonuclease activity that nicked depurinated form I simian virus 40 DNA. Apurinic/apyrimidinic endonuclease activity was also found in extracts of Escherichia coli infected with T4 denV + phage. Extracts of cells infected with T4 denV mutants contained significantly lower levels of apurinic/apyrimidinic endonuclease activity; these levels were no greater than the levels present in extracts of uninfected cells. Furthermore, the addition of DNA containing UV-irradiated DNA and T4 enzyme resulted in competition for pyrimidine dimer-DNA glycosylase activity against the UV-irradiated DNA. On the basis of these results, we concluded that apurinic/apyrimidinic endonuclease activity is encoded by the denV gene of phage T4, the same gene that codes for pyrimidine dimer-DNA glycosylase activity

  18. Corrosion Studies of Platinum Nano-Particles for Fuel Cells

    DEFF Research Database (Denmark)

    Shim, Signe Sarah

    The main focus of the present thesis is on corrosion and prevention of corrosion of platinum particles supported on carbon. This is important for instance in connection with start up and shutdown of fuel cells. The degradation mechanism of platinum particles supported on carbon has been character......The main focus of the present thesis is on corrosion and prevention of corrosion of platinum particles supported on carbon. This is important for instance in connection with start up and shutdown of fuel cells. The degradation mechanism of platinum particles supported on carbon has been...... characterized during oxygen reduction reaction (ORR) condition using identical location (IL) transmission electron microscopy (TEM). A TEM grid was used as the working electrode in an electrochemical setup allowing a direct correlation between the electrochemical response and the TEM analysis. The main results...... thirds and one monolayer of gold on platinum supported on carbon were synthesized by an inverse micelle method. The results obtained appear independent of the gold coverage. It has been shown that the electrochemical active surface areas of the platinum and platinum gold particles synthesized...

  19. Reaction pathways for reduction of nitrate ions on platinum, rhodium, and platinum-rhodium alloy electrodes

    International Nuclear Information System (INIS)

    Cunha, M.C.P.M. da; De Souza, J.P.I.; Nart, F.C.

    2000-01-01

    The reduction of nitrate ions on platinum, rhodium, and platinum-rhodium alloy electrodes has been investigated using differential electrochemical mass spectrometry and in situ FTIR measurements. For 3 M HNO 3 concentration it has been found that nitrate starts the reduction with partial N-O bond dissociation and N-N bond formation generating NO and N 2 O. At potentials lower than 0.2 V the reaction proceeds forming dissolved NH 4 + . For potentials lower than 0 V the reduction continues via a multiple pathway reaction leading to the nonselective production of N 2 , NH 2 OH, and N 2 H 2 . On the alloyed electrodes, the production of NO and N 2 O has been observed in both cathodic and anodic scans, while on pure platinum and rhodium electrodes the reaction has been observed only during the cathodic scan. Contrasting with the pure platinum and rhodium alloys, where the N-O bond break starts forming NO and N 2 O, on the alloys HNO 2 has been observed as the first reaction step. For alloys with higher rhodium composition, like Pt 75 Rh 25 , no N 2 has been detected for potentials lower than 0 V

  20. Heteroaryl ethers by oxidative palladium catalysis of pyridotriazol-1-yloxy pyrimidines with arylboronic acids.

    Science.gov (United States)

    Bardhan, Sujata; Wacharasindhu, Sumrit; Wan, Zhao-Kui; Mansour, Tarek S

    2009-06-18

    The oxidative palladium-catalyzed cross-coupling of pyrimidines containing pyridotriazol-1-yloxy (OPt) as either a urea or an amide functional group with arylboronic acids in the presence of Cs(2)CO(3) in DME containing 0.6-1.0% H(2)O is described for the preparation of heteroaryl ethers. The bromo substitution in the case of 3-(5-bromo-pyrimidin-2-yloxy)-3H-[1,2,3]triazolo[4,5-b]pyridine 1 could serve as a handle for further elaborations such as Suzuki coupling for attaching varied aryl groups.

  1. Outpatient desensitization in selected patients with platinum hypersensitivity reactions.

    Science.gov (United States)

    O'Malley, David M; Vetter, Monica Hagan; Cohn, David E; Khan, Ambar; Hays, John L

    2017-06-01

    Platinum-based chemotherapies are a standard treatment for both initial and recurrent gynecologic cancers. Given this widespread use, it is important to be aware of the features of platinum hypersensitivity reactions and the subsequent treatment of these reactions. There is also increasing interest in the development of desensitization protocols to allow patients with a history of platinum hypersensitivity to receive further platinum based therapy. In this review, we describe the management of platinum hypersensitivity reactions and the desensitization protocols utilized at our institution. We also describe the clinical categorizations utilized to triage patients to appropriate desensitization protocols. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. Dual certification for bank skyscrapers. A company headquarter gets a Green Building; Duale Zertifizierung fuer Bank-Tuerme. Eine Konzernzentrale wird zum Green Building

    Energy Technology Data Exchange (ETDEWEB)

    Luft, Christian; Bauer, Michael [Drees und Sommer Advanced Building Technologies GmbH, Stuttgart (Germany)

    2011-07-01

    Fire protection regulations force the Deutsche Bank AG (Frankfurt/Main, Federal Republic of Germany) to extensive reorganization measures in order to continuously operate their buildings. As part of a complete renovation, Deutsche Bank AG has stipulated a modern, innovative and sustainable example. This is confirmed by the Green Building Certification with the US american label LEED registered in Platinum as well as the German sustainability certificate of the Germain Sustainable Building Council (Stuttgart, Federal Republic of Germany) in gold.

  3. Analgesic Activity of Some 1,2,4-Triazole Heterocycles Clubbed with Pyrazole, Tetrazole, Isoxazole and Pyrimidine

    OpenAIRE

    Gajanan Khanage, Shantaram; Raju, Appala; Baban Mohite, Popat; Bhanudas Pandhare, Ramdas

    2013-01-01

    Purpose: In the present study in vivo analgesic activity of some previously synthesized 1,2,4-triazole derivatives containing pyrazole, tetrazole, isoxazole and pyrimidine ring have been evaluated. Methods: Acetic acid induced writhing method and Hot plate method has been described to study analgesic activity of some 1,2,4-triazole derivatives containing pyrazole, tetrazole, isoxazole and pyrimidine as a pharmacological active lead. Results: Thirty six different derivatives con...

  4. Platinum stable isotopes in ferromanganese crust and nodules

    Science.gov (United States)

    Corcoran, Loretta; Seward, Terry; Handler, Monica R.

    2015-04-01

    Hydrogenetic ferromanganese (Fe-Mn) crust and nodules are slow-growing chemical sediments that form by direct precipitation from seawater, resulting in a record of changing seawater chemistry. These sediments are the primary sink for platinum in the modern oxic marine environment, hosting well-documented enrichments over other platinum-group elements (PGEs): the Pt anomaly [1]. Platinum is a non-bio-essential, highly siderophile, transition metal with six stable isotopes (190Pt, 192Pt, 194Pt, 195Pt, 196Pt, and 198Pt) with several oxidation states (Pt0, Pt2+ and Pt4+). Platinum is generally considered to exist in the hydrosphere as Pt2+ although its behaviour in the marine environment is poorly constrained, and Pt4+may also be present. Variations in ocean redox state, together with changes in source fluxes to the oceans, may therefore lead to small variations (Leaching experiments conducted on platinum rich terrestrial materials underwent platinum stable isotopic measurement as an analogue for the Pt isotopic fractionation associated with continental weathering. [1] Hodge, V.F. et al. (1985) Earth and Planetary Science Letters, 72, 158-162. [2] Creech, J. et al. (2013) Journal of Analytical Atomic Spectrometry, 28. 853-865.

  5. Green Gold

    International Nuclear Information System (INIS)

    Salamandra Martinez, Carlos

    2004-01-01

    The main purpose of this work is to offer a general panoramic of the processes or experiences pilot that are carried out in the Project Green Gold, as strategy of environmental sustainability and organizational invigoration in Choco, especially in the 12 communities of the municipalities of Tado and Condoto. It is also sought to offer a minimum of information on the techniques of handmade production and to show the possibilities to carry out in a rational way the use and use of the natural resources. The Project Green Gold is carried out by the Corporation Green Gold (COV) and co-financed with resources of international and national character, the intervention of the financial resources it achievement mainly for the use of clean processes in the extraction stages and metals benefit. The project is centered primarily in the absence of use of products or toxic substances as the mercury, fair trade, organizational invigoration, execution of 11 approaches and certification of the metals Gold and Platinum. The COV, it has come executing the proposal from the year 2001 with the premise of contributing to the balance between the rational exploitation of the natural resources and the conservation of the environment in the Choco. In the project they are used technical handmade characteristic of the region framed inside the mining activity and production activities are diversified in the productive family units. Those producing with the support of entities of juridical character, specify the necessary game rules for the extraction and products commercialization

  6. Pyrimidine dimers are not the principal pre-mutagenic lesions induced in lambda phage DNA by ultraviolet light

    International Nuclear Information System (INIS)

    Wood, R.D.

    1985-01-01

    Experiments were performed to examine the role of cyclobutyl pyrimidine dimers in the process of mutagenesis by ultraviolet light. Lambda phage DNA was irradiated with u.v. and then incubated with an Escherichia coli photoreactivating enzyme, which monomerizes cyclobutyl pyrimidine dimers upon exposure to visible light. The photoreactivated DNA was packaged into lambda phage particles, which were used to infect E. coli uvr - host cells that had been induced for SOS functions by ultraviolet irradiation. Photoreactivation removed most toxic lesions from irradiated phage, but did not change the frequency of induction of mutations to the clear-plaque phenotype. This implies that cyclobutyl pyrimidine dimers can be lethal, but usually do not serve as sites of mutations in the phage. The DNA sequences of mutants, derived from photoreactivated DNA showed that almost two-thirds (16/28) were transitions, the same fraction found for u.v. mutagenesis without photoreactivation. Thus the lesion inducing transitions is not the cyclobutyl pyrimidine dimer. Photoreactivation of SOS-induced host cells before infection with u.v.-irradiated phage reduced mutagenesis substantially. In this case, photoreversal of cyclobutyl dimers serves to reduce expression of the SOS functions that are required in targeted u.v. mutagenesis. (author)

  7. Iodometric determination of platinum(4) using amperometry

    International Nuclear Information System (INIS)

    Zakharov, V.A.; Gavva, N.F.; Songina, O.A.

    1976-01-01

    The possibility of iodometric determination of platinum (4) by amperometric titration has been investigated. Titration has been conducted at zero potential of platinum reference electrode. Voltampere curves and absorption spectra of the solutions have been recorded to elucidate the nature of platinum (4) interaction with iodide-ion. It has been established that in the case of small excess of iodide complex [PtI 6 ] 2- is formed. When there is a considerable excess of KI, platinum (4) is reduced to Pt(2) with the formation of [PtI 4 ] 2 - and liberation of free iodine. Optimal for iodometric titration of Pt(4) is the use of acetate ot phosphate background solution with pH 6-8 with respect to 1M KI which is attained by adding 3 g of solid KI to 20 ml of the solution being titrated. Under these conditions the limit of platinum detection is 0.5 mkg/ml. Determination of Pt (4) is not hindered by the presence of 200-fold amounts of Cr(6), V(5), and Ni(2) as well as by 20-10-fold amounts of As(5), Sb(5), Se(4), Te(4), Rh(3), and Ir(3), Determination is hindered by the presence of Pd(2), Fe(3), Ir(4), and Cu(2) which, however, can easily be overcome. The possibility has been shown of using the developed technique for analysis of platinum catalysts and alloys

  8. Rhenium–platinum antitumor systems

    Directory of Open Access Journals (Sweden)

    A. V. Shtemenko

    2017-04-01

    Full Text Available This review provides an overlook of design (in short, antitumor and other biological activity of quadruple-bonded cluster dirhenium(III compounds and their synergism with cisplatin. In particular, we describe the work of the rhenium-platinum antitumor system (introduction of rhenium and platinum compounds. Among known metal-based anticancer drugs and drug candidates dirhenium(III compounds differ profoundly due to their strong antiradical and antioxidant properties determined by quadruple bond unsaturation. Such advantages of metal complexes as more expressed redox chemical propertie should be exploited for creating more efficient anticancer drugs. Combination of drugs leads to synergistic effects and/or to lowe­ring toxicity of platinides and is very promising in cancer chemotherapy. The review covers the follo­wing items: design of quadruple bonded dirhenium(III clusters, their spectral and antiradical properties (in short; interaction of the dirhenium(III compounds with lipids and formation of liposomes; interaction of the dirhenium(III compounds with erythrocytes and their antihemolytic activity in the models of hemolytic anemia; anticancer activity of dirhenium clusters and work of the rhenium-platinum antitumor system; antianemic and antioxidant properties of the dirhenium(III compounds in the model of tumor growth; interaction of the dirhenium(III compounds with nucleobases and DNA. Some modern trends in the field of bioinorganic and medicinal chemi­stry are also considered regarding their connection to the rhenium-platinum system efficiency: use of combinational therapy and nanomaterials; involvement of some biologically active ligands and redox-activation strategy, etc.

  9. A NEW EMPIRICAL INVESTIGATION OF THE PLATINUM SPOT RETURNS

    Directory of Open Access Journals (Sweden)

    Simone Kruse

    2017-08-01

    Full Text Available The global platinum market has been in downturn and unstable for five consecutive years, and thus market participants are demanding effective quantitative risk management tools. Since platinum is so widely used and serves as an important investment vehicle, the importance of risk management of platinum spot returns cannot be understated. In this paper, we take advantage of a very popular econometric model, the generalized autoregressive conditional heteroscedasticity (GARCH model, for platinum returns. We received two important findings by using the conventional GARCH models in explain daily platinum spot returns. First, it is crucial to introduce heavy-tailed distribution to explain conditional heavy tails; and second, the NRIG distribution performs better than the most widely-used heavy-tailed distribution, the Student’s t distribution.

  10. Mechanism of Platinum Derivatives Induced Kidney Injury

    Directory of Open Access Journals (Sweden)

    Feifei YAN

    2015-09-01

    Full Text Available Platinum derivatives are the most widely used chemotherapeutic agents to treat solid tumors including ovarian, head and neck, and testicular germ cell tumors, lung cancer, and colorectal cancer. Two major problems exist, however, in the clinic use of platinum derivatives. One is the development of tumor resistance to the drug during therapy, leading to treatment failure. The other is the drug’s toxicity such as the cisplatin’s nephrotoxicity, which limits the dose that can be administered. This paper describes the mechanism of platinum derivatives induced kidney injury.

  11. Collective Behavior of Water on Platinum

    Science.gov (United States)

    Limmer, David; Willard, Adam; Chandler, David

    2012-02-01

    We present the results of molecular dynamics simulations of a interface between water and a platinum electrode. Using importance sampling techniques we probe a variety of collective phenomenon that emerge at the interface. We consider platinum electrodes with two different geometries and discuss how different behaviors result from a competition between geometrical frustration and favorable local interactions.

  12. Study of gold-platinum and platinum-gold surface modification and its influence on hydrogen evolution and oxygen reduction

    Directory of Open Access Journals (Sweden)

    BRANIMIR N. GRGUR

    2005-02-01

    Full Text Available Surface modification of the electrodes was conducted from sulfuric acid solutions containing the corresponding metal–chloride complexes using cyclic voltammetry. Comparing the charges of the hydrogen underpotential deposition region, and the corresponding oxide reduction regions, it is concluded that a platinum overlayer on gold forms 3D islands, while gold on platinum forms 2D islands. Foreign metals present in an amount of up to one monolayer exert an influence on the change in reaction rate with respect to both hydrogen evolution (HER and oxygen reduction (ORR reactions. Aplatinum overlayer on a gold substrate increases the activity forHER and for ORR, compared with pure gold. These results can be understood in terms of a simple model, in which the change in the H and OH binding energies are directly proportional to the shift of the d-bond center of the overlayer. On the contrary, a gold layer on platinum slightly decreases the activity for both reactions compared with pure platinum.

  13. Critical importance of the de novo pyrimidine biosynthesis pathway for Trypanosoma cruzi growth in the mammalian host cell cytoplasm

    International Nuclear Information System (INIS)

    Hashimoto, Muneaki; Morales, Jorge; Fukai, Yoshihisa; Suzuki, Shigeo; Takamiya, Shinzaburo; Tsubouchi, Akiko; Inoue, Syou; Inoue, Masayuki; Kita, Kiyoshi; Harada, Shigeharu; Tanaka, Akiko; Aoki, Takashi; Nara, Takeshi

    2012-01-01

    Highlights: ► We established Trypanosoma cruzi lacking the gene for carbamoyl phosphate synthetase II. ► Disruption of the cpsII gene significantly reduced the growth of epimastigotes. ► In particular, the CPSII-null mutant severely retarded intracellular growth. ► The de novo pyrimidine pathway is critical for the parasite growth in the host cell. -- Abstract: The intracellular parasitic protist Trypanosoma cruzi is the causative agent of Chagas disease in Latin America. In general, pyrimidine nucleotides are supplied by both de novo biosynthesis and salvage pathways. While epimastigotes—an insect form—possess both activities, amastigotes—an intracellular replicating form of T. cruzi—are unable to mediate the uptake of pyrimidine. However, the requirement of de novo pyrimidine biosynthesis for parasite growth and survival has not yet been elucidated. Carbamoyl-phosphate synthetase II (CPSII) is the first and rate-limiting enzyme of the de novo biosynthetic pathway, and increased CPSII activity is associated with the rapid proliferation of tumor cells. In the present study, we showed that disruption of the T. cruzicpsII gene significantly reduced parasite growth. In particular, the growth of amastigotes lacking the cpsII gene was severely suppressed. Thus, the de novo pyrimidine pathway is important for proliferation of T. cruzi in the host cell cytoplasm and represents a promising target for chemotherapy against Chagas disease.

  14. Intramolecular Diels-Alder reactions of pyrimidines, a synthetic and computational study

    NARCIS (Netherlands)

    Stolle, W.A.W.

    1992-01-01

    This thesis deals with an investigation on the ringtransformation reactions of 2and 5-(ω-alkynyl)pyrimidine derivatives, which undergo upon heating an intramolecular Diels-Alder reaction and subsequently a spontaneous retro Diels- Alder reaction. To get a better insight into the

  15. Tumour radiosensitization with the halogenated pyrimidines 5'-bromo-and 5'-iododeoxyuridine

    International Nuclear Information System (INIS)

    Epstein, A.H.; Cook, J.A.; Goffman, T.; Glatstein, E.

    1993-01-01

    The authors review studies of the use of iododeoxyuridine (IdUrd) and bromodeoxyuridine as radiosensitizers and attempt to correlate the clinical outcome for patients treated with radiation and IdUrd with the extent of halogenated pyrimidine cellular uptake and incorporation. (U.K.)

  16. Fluorescent property of 3-hydroxymethyl imidazo[1,2-a]pyridine and pyrimidine derivatives

    Directory of Open Access Journals (Sweden)

    Velázquez-Olvera Stephania

    2012-08-01

    Full Text Available Abstract Background Imidazo[1,2-a]pyridines and pyrimidines are important organic fluorophores which have been investigated as biomarkers and photochemical sensors. The effect on the luminescent property by substituents in the heterocycle and phenyl rings, have been studied as well. In this investigation, series of 3-hydroxymethyl imidazo[1,2-a]pyridines and pyrimidines were synthesized and evaluated in relation to fluorescence emission, based upon the hypothesis that the hydroxymethyl group may act as an enhancer of fluorescence intensity. Results Compounds of both series emitted light in organic solvents dilutions as well as in acidic and alkaline media. Quantitative fluorescence spectroscopy determined that both fused heterocycles fluoresced more intensely than the parent unsubstituted imidazo[1,2-a]azine fluorophore. In particular, 3-hydroxymethyl imidazo[1,2-a]pyridines fluoresced more intensely than 3-hydroxymethyl imidazo[1,2-a]pyrimidines, the latter emitting blue light at longer wavelengths, whereas the former emitted purple light. Conclusion It was concluded that in most cases the hydroxymethyl moiety did act as an enhancer of the fluorescence intensity, however, a comparison made with the fluorescence emitted by 2-aryl imidazo[1,2-a]azines revealed that in some cases the hydroxymethyl substituent decreased the fluorescence intensity.

  17. Radiation-induced DNA damage in halogenated pyrimidine incorporated cells and its correlation with radiosensitivity

    International Nuclear Information System (INIS)

    Watanabe, R.; Nikjoo, H.

    2003-01-01

    Cells with DNA containing 5-halogenated pyrimidines in place of thymidine show significant reductions of slope (Do) and shoulder (Dq) of their radiation survival curves. Similar radiosensitization has also been observed in the yield of DNA strand breaks. The purpose of this study is to obtain an insight into the mechanism of cell lethality by examining the relationship between the spectrum of DNA damage and the cell survival. In this study we estimated the enhancement of strand breaks due to incorporation of halogenated pyrimidine, the complexity of DNA damage and the probability of the initial DNA damage leading to cell inactivation. Monte Carlo track structure methods were used to model and simulate the induction of strand breakage by X-rays. The increase of DNA strand break was estimated by assuming the excess strand break was caused by the highly reactive uracil radicals at the halouracil substituted sites. The assumption of the enhancement mechanism of strand breaks was examined and verified by comparison with experimental data for induction of SSB and DSB. The calculated DNA damage spectrum shows the increase in complexity of strand breaks is due to incorporation of halogenated pyrimidines. The increase in the yield of DSB and cell lethality show similar trend at various degrees of halogenated pyrimidine substitution. We asked the question whether this agreement supports the hypothesis that DSB is responsible for cell lethality? The estimated number of lethal damage from the cell survival using a linear-quadratic model is much less than the initial yield of DSB. This work examines the correlation of cell lethality as a function of frequencies of complex form of double strand breaks

  18. Pyrimidine dimer sites associated with the daughter DNA strands in uv-irradiated human fibroblasts

    Energy Technology Data Exchange (ETDEWEB)

    Lehmann, A R; Kirk-Bell, S [Sussex Univ., Brighton (UK)

    1978-03-01

    Pyrimidine dimer sites associated with the newly-synthesized DNA were detected during post-replication repair of DNA in uv-irradiated human fibroblasts. These pyrimidine dimer sites were inferred from a decrease in the molecular weight of pulse-labelled DNA after treatment with an extract of Micrococcus luteus containing uv-specific endonuclease activity. In DNA synthesized immediately after irradiation, the frequency of these daughter strand dimer sites was 7 to 20% of that in the parental DNA. Such sites were found in fibroblasts from normal donors and from xeroderma pigmentosum patients (with defects in excision-repair or post-replication repair). They were excised from the DNA of normal cells. As the time between uv irradiation and pulse-labelling was increased, the frequency of dimer sites associated with the labelled DNA decreased. If the pulse-label was delivered 6 h after irradiation of normal cells or excision-defective xeroderma pigmentosum cells, no dimer sites were detected in the labelled DNA. It has usually been assumed that daughter-strand dimer sites were the result of recombinational exchanges. The assay procedure used in these experiments and in similar experiments of others did not distinguish between labelled DNA containing pyrimidine dimers within the labelled section, and labelled DNA which did not contain pyrimidine dimers but was attached to unlabelled DNA which did contain dimers. The latter structures would arise during normal replication immediately following uv irradiation of mammalian cells. Calculations are presented which suggest that a significant proportion and conceivably all of the dimer sites associated with the daughter strands may have arisen in this way, rather than from recombinational exchanges as has been generally assumed.

  19. Pyrimidine dimer sites associated with the daughter DNA strands in UV-irradiated human fibroblasts

    International Nuclear Information System (INIS)

    Lehmann, A.R.; Kirk-Bell, S.

    1978-01-01

    Pyrimidine dimer sites associated with the newly-synthesized DNA were detected during post-replication repair of DNA in UV-irradiated human fibroblasts. These pyrimidine dimer sites were inferred from a decrease in the molecular weight of pulse-labelled DNA after treatment with an extract of Micrococcus luteus containing UV-specific endonuclease activity. In DNA synthesized immediately after irradiation the frequency of these daughter strand dimer sites was 7-20% of that in the parental DNA. Such sites were found in fibroblasts from normal donors and from xeroderma pigmentosum patients (with defects in excision-repair or post-replication repair). They were excised from the DNA of normal cells. As the time between UV-irradiation and pulse-labelling was increased, the frequency of dimer sites associated with the labelled DNA decreased. If the pulse-label was delivered 6 h after irradiation of normal cells or excision-defective xeroderma pigmentosum cells, no dimer sites were detected in the labelled DNA. It has usually been assumed that daughter-strand dimer sites were the result of recombinational exchanges. The assay procedure used in these experiments and in similar experiments of others did not distinguish between labelled DNA containing pyrimidine dimers within the labelled section, and labelled DNA which did not contain pyrimidine dimers but was attached to unlabelled DNA which did contain dimers. The latter structures would arise during normal replication immediately following UV-irradiation of mammalian cells. Calculations are presented which suggest that a significant proportion and conceivably all of the dimer sites associated with the daughter strands may have arisen in this way, rather than from recombinational exchanges as has been generally assumed. (author)

  20. The pyrimidine operon pyrRPB-carA from Lactococcus lactis

    DEFF Research Database (Denmark)

    Martinussen, Jan; Schallert, J.; Andersen, Birgit

    2001-01-01

    The four genes pyrR, pyrP, pyrB, and carA were found to constitute an operon in Lactococcus lactis subsp, lactis MG1363. The functions of the different genes were established by mutational analysis. The first gene in the operon is the pyrimidine regulatory gene, pyrR, which is responsible...

  1. Recovery of Platinum from Dilute Chloride Media Using Biosorbents

    Science.gov (United States)

    Zeytuncu, B.; Morcali, M. H.; Yucel, O.

    Pistachio nut shells and Rice husk, a biomass residue, were investigated as adsorbents for the platinum uptake from synthetically prepared dilute chloroplatinic acid solutions. The effects of the different uptake parameters on platinum uptake (%) were studied in detail on a batch sorption. Before the pistachio nut shell material was activated, platinum uptake (%) was poor compared with rice husk. However, after the pistachio nut shell material was activated at 1000°C under an argon atmosphere, the platinum uptake (%) increased two-fold. The pistachio nut shell (inactivated and activated) and rice husk were characterized by Attenuated Total Reflection-Fourier transform infrared spectroscopy (ATR-FTIR).

  2. Oxidation of pyrimidine nucleosides and nucleotides by osmium tetroxide.

    Science.gov (United States)

    Burton, K

    1967-08-01

    1. Pyrimidine nucleosides such as thymidine, uridine or cytidine are oxidized readily at 0 degrees by osmium tetroxide in ammonium chloride buffer. There is virtually no oxidation in bicarbonate buffer of similar pH. Oxidation of 1-methyluracil yields 5,6-dihydro-4,5,6-trihydroxy-1-methyl-2-pyrimidone. 2. Osmium tetroxide and ammonia react reversibly in aqueous solution to form a yellow 1:1 complex, probably OsO(3)NH. A second molecule of ammonia must be involved in the oxidation of UMP since the rate of this reaction is approximately proportional to the square of the concentration of unprotonated ammonia. 3. 4-Thiouridine reacts with osmium tetroxide much more rapidly than does uridine. The changes of absorption spectra are different in sodium bicarbonate buffer and in ammonium chloride buffer. They occur faster in the latter buffer and, under suitable conditions, cytidine is a major product. 4. Polyuridylic acid is oxidized readily by ammoniacal osmium tetroxide, but its oxidation is inhibited by polyadenylic acid. Pyrimidines of yeast amino acid-transfer RNA are oxidized more slowly than the corresponding mononucleosides, especially the thymine residues. Appreciable oxidation can occur without change of sedimentation coefficient.

  3. Bio-inspired routes for synthesizing efficient nanoscale platinum electrocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Jennifer N. [Univ. of California, San Diego, CA (United States); Wang, Joseph [Univ. of California, San Diego, CA (United States)

    2014-08-31

    The overall objective of the proposed research is to use fundamental advances in bionanotechnology to design powerful platinum nanocrystal electrocatalysts for fuel cell applications. The new economically-viable, environmentally-friendly, bottom-up biochemical synthetic strategy will produce platinum nanocrystals with tailored size, shape and crystal orientation, hence leading to a maximum electrochemical reactivity. There are five specific aims to the proposed bio-inspired strategy for synthesizing efficient electrocatalytic platinum nanocrystals: (1) isolate peptides that both selectively bind particular crystal faces of platinum and promote the nucleation and growth of particular nanocrystal morphologies, (2) pattern nanoscale 2-dimensional arrays of platinum nucleating peptides from DNA scaffolds, (3) investigate the combined use of substrate patterned peptides and soluble peptides on nanocrystal morphology and growth (4) synthesize platinum crystals on planar and large-area carbon electrode supports, and (5) perform detailed characterization of the electrocatalytic behavior as a function of catalyst size, shape and morphology. Project Description and Impact: This bio-inspired collaborative research effort will address key challenges in designing powerful electrocatalysts for fuel cell applications by employing nucleic acid scaffolds in combination with peptides to perform specific, environmentally-friendly, simultaneous bottom-up biochemical synthesis and patterned assembly of highly uniform and efficient platinum nanocrystal catalysts. Bulk synthesis of nanoparticles usually produces a range of sizes, accessible catalytic sites, crystal morphologies, and orientations, all of which lead to inconsistent catalytic activities. In contrast, biological systems routinely demonstrate exquisite control over inorganic syntheses at neutral pH and ambient temperature and pressures. Because the orientation and arrangement of the templating biomolecules can be precisely

  4. Radiation and platinum drug interaction

    International Nuclear Information System (INIS)

    Nias, A.H.W.

    1985-01-01

    The ideal platinum drug-radiation interaction would achieve radiosensitization of hypoxic tumour cells with the use of a dose of drug which is completely non-toxic to normal tissues. Electron-affinic agents are employed with this aim, but the commoner platinum drugs are only weakly electron-affinic. They do have a quasi-alkylating action however, and this DNA targeting may account for the radiosensitizing effect which occurs with both pre- and post-radiation treatments. Because toxic drug dosage is usually required for this, the evidence of the biological responses to the drug and to the radiation, as well as to the combination, requires critical analysis before any claim of true enhancement, rather than simple additivity, can be accepted. The amount of enhancement will vary with both the platinum drug dose and the time interval between drug administration and radiation. Clinical schedules may produce an increase in tumour response and/or morbidity, depending upon such dose and time relationships. (author)

  5. Structures of 38-atom gold-platinum nanoalloy clusters

    Energy Technology Data Exchange (ETDEWEB)

    Ong, Yee Pin; Yoon, Tiem Leong [School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Lim, Thong Leng [Faculty of Engineering and Technology, Multimedia University, Melaka Campus, 75450 Melaka (Malaysia)

    2015-04-24

    Bimetallic nanoclusters, such as gold-platinum nanoclusters, are nanomaterials promising wide range of applications. We perform a numerical study of 38-atom gold-platinum nanoalloy clusters, Au{sub n}Pt{sub 38−n} (0 ≤ n ≤ 38), to elucidate the geometrical structures of these clusters. The lowest-energy structures of these bimetallic nanoclusters at the semi-empirical level are obtained via a global-minimum search algorithm known as parallel tempering multi-canonical basin hopping plus genetic algorithm (PTMBHGA), in which empirical Gupta many-body potential is used to describe the inter-atomic interactions among the constituent atoms. The structures of gold-platinum nanoalloy clusters are predicted to be core-shell segregated nanoclusters. Gold atoms are observed to preferentially occupy the surface of the clusters, while platinum atoms tend to occupy the core due to the slightly smaller atomic radius of platinum as compared to gold’s. The evolution of the geometrical structure of 38-atom Au-Pt clusters displays striking similarity with that of 38-atom Au-Cu nanoalloy clusters as reported in the literature.

  6. Effect of some pyrimidinic Schiff bases on the corrosion of mild steel in hydrochloric acid solution

    International Nuclear Information System (INIS)

    Ashassi-Sorkhabi, H.; Shaabani, B.; Seifzadeh, D.

    2005-01-01

    The efficiency of benzylidene-pyrimidin-2-yl-amine (A) (4-methyl-benzylidene)-pyrimidine-2-yl-amine (B) and (4-chloro-benzylidene)-pyrimidine-2-yl-amine, as corrosion inhibitors for mild steel in 1 M HCl have been determined by weight loss measurements and electrochemical polarization method. The results showed that these inhibitors revealed a good corrosion inhibition even at very low concentrations. Polarization curves indicate that all compounds are mixed type inhibitors. The effect of various parameters such as temperature and inhibitor concentration on the efficiency of the inhibitors has been studied. Activation energies of corrosion reaction in the presence and absence of inhibitors have been calculated. The adsorption of used compounds on the steel surface obeys Langmuir's isotherm. It appears that an efficient inhibition is characterized by a relatively greater decrease in free energy of adsorption. Significant correlations are obtained between inhibition efficiency and quantum chemical parameters using quantitative structure-activity relationship (QSAR) method

  7. Functional and genetic evidence that nucleoside transport is highly conserved in Leishmania species: Implications for pyrimidine-based chemotherapy.

    Science.gov (United States)

    Alzahrani, Khalid J H; Ali, Juma A M; Eze, Anthonius A; Looi, Wan Limm; Tagoe, Daniel N A; Creek, Darren J; Barrett, Michael P; de Koning, Harry P

    2017-08-01

    Leishmania pyrimidine salvage is replete with opportunities for therapeutic intervention with enzyme inhibitors or antimetabolites. Their uptake into cells depends upon specific transporters; therefore it is essential to establish whether various Leishmania species possess similar pyrimidine transporters capable of drug uptake. Here, we report a comprehensive characterization of pyrimidine transport in L. major and L. mexicana. In both species, two transporters for uridine/adenosine were detected, one of which also transported uracil and the antimetabolites 5-fluoruracil (5-FU) and 5F,2'deoxyuridine (5F,2'dUrd), and was designated uridine-uracil transporter 1 (UUT1); the other transporter mediated uptake of adenosine, uridine, 5F,2'dUrd and thymidine and was designated Nucleoside Transporter 1 (NT1). To verify the reported L. donovani model of two NT1-like genes encoding uridine/adenosine transporters, and an NT2 gene encoding an inosine transporter, we cloned the corresponding L. major and L. mexicana genes, expressing each in T. brucei. Consistent with the L. donovani reports, the NT1-like genes of either species mediated the adenosine-sensitive uptake of [ 3 H]-uridine but not of [ 3 H]-inosine. Conversely, the NT2-like genes mediated uptake of [ 3 H]-inosine but not [ 3 H]-uridine. Among pyrimidine antimetabolites tested, 5-FU and 5F,2'dUrd were the most effective antileishmanials; resistance to both analogs was induced in L. major and L. mexicana. In each case it was found that the resistant cells had lost the transport capacity for the inducing drug. Metabolomics analysis found that the mechanism of action of 5-FU and 5F-2'dUrd was similar in both Leishmania species, with major changes in deoxynucleotide metabolism. We conclude that the pyrimidine salvage system is highly conserved in Leishmania species - essential information for the development of pyrimidine-based chemotherapy. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights

  8. Crystal structures of 2-[(4,6-di-amino-pyrimidin-2-yl)sulfan-yl]-N-(naphthalen-1-yl)acetamide and 2-[(4,6-di-amino-pyrimidin-2-yl)sulfan-yl]-N-(4-fluoro-phen-yl)acetamide.

    Science.gov (United States)

    Subasri, S; Kumar, Timiri Ajay; Sinha, Barij Nayan; Jayaprakash, Venkatesan; Viswanathan, Vijayan; Velmurugan, Devadasan

    2017-02-01

    The title compounds, C 16 H 15 N 5 OS, (I), and C 12 H 12 FN 5 OS, (II), are [(di-amino-pyrimidine)-sulfan-yl]acetamide derivatives. In (I), the pyrimidine ring is inclined to the naphthalene ring system by 55.5 (1)°, while in (II), the pyrimidine ring is inclined to the benzene ring by 58.93 (8)°. In (II), there is an intra-molecular N-H⋯N hydrogen bond and a short C-H⋯O contact. In the crystals of (I) and (II), mol-ecules are linked by pairs of N-H⋯N hydrogen bonds, forming inversion dimers with R 2 2 (8) ring motifs. In the crystal of (I), the dimers are linked by bifurcated N-H⋯(O,O) and C-H⋯O hydrogen bonds, forming layers parallel to (100). In the crystal of (II), the dimers are linked by N-H⋯O hydrogen bonds, also forming layers parallel to (100). The layers are linked by C-H⋯F hydrogen bonds, forming a three-dimensional architecture.

  9. Determination of trace platinum by supramolecular catalytic kinetic spectrofluorimetry of {beta}-cyclodextrin-platinum-KBrO{sub 3}-salicylaldehyde furfuralhydrazone

    Energy Technology Data Exchange (ETDEWEB)

    Tang, Bo; Zhang, Ning; Chen, Zhen-Zhen; Kong, Qing-Cheng [Shandong Normal University, College of Chemistry, Chemical Engineering and Materials Science, Jinan (China)

    2006-02-01

    A supramolecular catalytic kinetic spectrofluorimetric method was developed for the determination of platinum(IV) and the possible mechanism of catalytic reaction was discussed. The method was based on the fluorescence-enhancing reaction of salicylaldehyde furfuralhydrazone (SAFH) with potassium bromate, which was catalysed by platinum(IV) in a water-ethanol medium. {beta}-Cyclodextrin ({beta}-CD) obviously sensitized the determination at pH 5.20 and 25 C. Under optimum conditions, the {beta}-CD-platinum-KBrO{sub 3}-SAFH supramolecular kinetic catalytic reaction system had excitation and emission maxima at 372 and 461 nm, respectively. The linear range of this method was 0.60-180 ng ml{sup -1} with a relative standard deviation of 1.2%, and the detection limit was 0.18 ng ml{sup -1}. Investigation of the mechanism and the effects of interferences is presented. The proposed method was applied successfully to determine trace platinum(IV) in the chemotherapeutic drug cisplatin and serum from patients with satisfactory results. (orig.)

  10. Platinum-group metals from nuclear reactions as a possible resource

    International Nuclear Information System (INIS)

    Jensen, G.A.

    1985-03-01

    Spent nuclear fuels contain significant quantities of three of the platinum-group metals (ruthenium, rhodium, and palladium), and a related element technetium, which is nearly absent in nature. Applications for ruthenium, rhodium, and palladium are well established. Since the supply of these and other platinum metals is largely from foreign sources, they are considered strategic materials. Existing and future spent nuclear fuels contain quantities of these platinum metals that exceed the United States reserve base. Technetium has properties similar to platinum metals and has unique, useful properties of its own. The technical feasibility of recovering and using fission product platinum metals (and technetium) extensively in industry depends on: thoroughly decontaminating platinum-group metals from all other radioactive materials in the waste stream; separating platinum-group metals from one another in very high purity; using applications where appropriate control of the residual radioactivity is possible; and whether or not the United States will recover or process spent fuel prior to repository storage. If the radioactivity must be removed, isotope separation or long term storage to allow decay of the contained radioisotopes may be possible. 7 figs., 7 tabs

  11. High performance platinum single atom electrocatalyst for oxygen reduction reaction

    Science.gov (United States)

    Liu, Jing; Jiao, Menggai; Lu, Lanlu; Barkholtz, Heather M.; Li, Yuping; Wang, Ying; Jiang, Luhua; Wu, Zhijian; Liu, Di-Jia; Zhuang, Lin; Ma, Chao; Zeng, Jie; Zhang, Bingsen; Su, Dangsheng; Song, Ping; Xing, Wei; Xu, Weilin; Wang, Ying; Jiang, Zheng; Sun, Gongquan

    2017-07-01

    For the large-scale sustainable implementation of polymer electrolyte membrane fuel cells in vehicles, high-performance electrocatalysts with low platinum consumption are desirable for use as cathode material during the oxygen reduction reaction in fuel cells. Here we report a carbon black-supported cost-effective, efficient and durable platinum single-atom electrocatalyst with carbon monoxide/methanol tolerance for the cathodic oxygen reduction reaction. The acidic single-cell with such a catalyst as cathode delivers high performance, with power density up to 680 mW cm-2 at 80 °C with a low platinum loading of 0.09 mgPt cm-2, corresponding to a platinum utilization of 0.13 gPt kW-1 in the fuel cell. Good fuel cell durability is also observed. Theoretical calculations reveal that the main effective sites on such platinum single-atom electrocatalysts are single-pyridinic-nitrogen-atom-anchored single-platinum-atom centres, which are tolerant to carbon monoxide/methanol, but highly active for the oxygen reduction reaction.

  12. Platinum uptake from chloride solutions using biosorbents

    Directory of Open Access Journals (Sweden)

    Mehmet Hakan Morcali

    2013-04-01

    Full Text Available Present work investigates platinum uptake from synthetically prepared, dilute platinum-bearing solutions using biomass residues, i.e. pistachio nut shell and rice husk, which are abundant in Turkey, and provides a comparison between these two biosorbents. Effects of the different uptake parameters, sorbent dosage, contact time, temperature and pH of solution on platinum uptake (% were studied in detail on a batch sorption. Before the pistachio nut shell was activated, platinum uptake (% was poor compared to the rice husk. However, after the pistachio nut shell was activated at 1000 °C under an argon atmosphere, the platinum uptake (% increased two-fold. The pistachio nut shell (original and activated and rice husk were shown to be better than commercially available activated carbon in terms of adsorption capacity. These two sorbents have also been characterized by FTIR and SEM. Adsorption equilibrium data best complied with the Langmuir isotherm model. Maximum adsorption capacities, Qmax, at 25 °C were found to be 38.31 and 42.02 mg.g- 1for the activated pistachio nut shell and rice husk, respectively. Thermodynamic calculations using the measured ∆H°, ∆S° and ∆G° values indicate that the uptake process was spontaneous and endothermic. The experimental data were shown to be fit the pseudo-second-order kinetic model.

  13. cis-Aquadichlorido[pyrimidin-2(1H-one-κN3]copper(II

    Directory of Open Access Journals (Sweden)

    A. Guy Orpen

    2008-07-01

    Full Text Available In the title compound, [CuCl2(C4H4N2O(H2O], the CuII cation is coordinated by two chloride anions, one pyrimidin-2-one N atom and one water molecule, giving a slightly distorted square-planar geometry. In the crystal structure, the pyrimidin-2-one rings stack along the b axis, with an interplanar distance of 3.306 Å, as do the copper coordination planes (interplanar spacing = 2.998 Å. The coordination around the Jahn–Teller-distorted CuII ion is completed by long Cu...O [3.014 (5 Å] and Cu...Cl [3.0194 (15 Å] interactions with adjacent molecules involved in this stacking. Several N—H...Cl, O—H...Cl and O—H...O intermolecular hydrogen bonds form a polar three-dimensional network.

  14. Graphite-supported platinum catalysts: Effects of gas and aqueous phase treatments

    Energy Technology Data Exchange (ETDEWEB)

    Vleeming, J.H.; Kuster, B.F.M.; Marin, G.B. [Eindhoven Univ. of Technology (Netherlands)] [and others

    1997-03-01

    The effects on the platinum particle diameter and the available platinum surface area of a graphite-supported platinum catalyst resulting from pretreatments and from performing a selective oxidation reaction are investigated. In the gas phase considerable catalyst sintering occurs only in the presence of oxygen at 773 K due to extensive carbon burn-off, whereas in an aqueous phase platinum particle growth is limited upon oxidative treatment. A hydrogen treatment in aqueous phase at 363 K causes platinum particle growth, aggregate formation, and covering of metal sites. These phenomena become more important with increasing pH. Platinum particle growth and aggregate formation are attributed to platinum particle rather than platinum adatom mobility and is caused by the destruction of the oxygen-containing surface groups on the graphite support, which serve as anchorage sites for the platinum particles. Site covering is caused by products originating from the graphite support, which are formed as a result of the reductive treatments. When performing the aqueous phase oxidation of methyl {alpha}-D-glucopyranoside at 323 K and a pH of 9, catalyst modifications are small under oxidative conditions. Exposure of the catalyst for several hours to methyl {alpha}-D-glucopyranoside under the same conditions but in the absence of oxygen causes site covering. 50 refs., 9 figs., 1 tab.

  15. OFFGEL isoelectric focusing and polyacrylamide gel electrophoresis separation of platinum-binding proteins.

    Science.gov (United States)

    Mena, Ma Luz; Moreno-Gordaliza, Estefanía; Moraleja, Irene; Cañas, Benito; Gómez-Gómez, Ma Milagros

    2011-03-04

    In this work a 2D electrophoretic separation procedure able to maintain the integrity of platinum-protein bonds has been developed. The method is based on the use of sequential OFFGEL isoelectric focussing (IEF) and PAGE. A systematic study of the reagents used for PAGE, for OFFGEL-IEF separation, and post-separation treatment of gels (such as enzymatic digestion and sample preparation for MS analysis) was tackled regarding their suitability for the identification of platinum binding proteins using standard proteins incubated with cisplatin. The distribution of platinum in high and low molecular weight fractions (separated by cut-off filters) was determined by ICP-MS, which allows evaluating platinum-protein bond stability under the conditions studied. SDS-PAGE in the absence of β-mercaptoethanol or dithiotreitol preserved the platinum-protein bonds. In addition, neither the influence of the electric field during the electrophoretic separation, nor the processes of fixing, staining and destaining of proteins in the gel did result in the loss of platinum from platinum binding proteins. SDS-PAGE under non-reducing conditions provides separation of platinum-binding proteins in very narrow bands with quantitative recoveries. Different amounts of platinum-bound proteins covering the range 0.3-2.0 μg were separated and mineralised for platinum determination, showing good platinum linearity. Limits of detection for a mixture of five standard proteins incubated with cisplatin were between the range of 2.4 and 13.9 pg of platinum, which were satisfactory for their application to biological samples. Regarding OFFGEL-IEF, a denaturing solution without thiourea and without dithiotreitol is recommended. The suitability of the OFFGEL-IEF for the separation of platinum binding proteins of a kidney cytosol was demonstrated. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Room temperature synthesis of colloidal platinum nanoparticles

    Indian Academy of Sciences (India)

    Unknown

    platinum cation used. ... Particle size increased with low reagent concentration. ... 2,100) was added separately to the starting solution. Argon gas was bubbled in the solution for 20 min. Later, reduction of platinum ions was carried out by bubbling hydrogen gas ... plex to aquate (Cl– → H2O ligand exchange). ... copper grid.

  17. Point defects in platinum

    International Nuclear Information System (INIS)

    Piercy, G.R.

    1960-01-01

    An investigation was made of the mobility and types of point defect introduced in platinum by deformation in liquid nitrogen, quenching into water from 1600 o C, or reactor irradiation at 50 o C. In all cases the activation energy for motion of the defect was determined from measurements of electrical resistivity. Measurements of density, hardness, and x-ray line broadening were also made there applicable. These experiments indicated that the principal defects remaining in platinum after irradiation were single vacant lattice sites and after quenching were pairs of vacant lattice sites. Those present after deformation In liquid nitrogen were single vacant lattice sites and another type of defect, perhaps interstitial atoms. (author)

  18. Platinum uptake by the freshwater isopod Asellus Aquaticus in urban rivers

    Energy Technology Data Exchange (ETDEWEB)

    Rauch, S.; Morrison, G.M. [Department of Sanitary Engineering, Chalmers University of Technology, S-412 96 Goeteborg (Sweden)

    1999-09-01

    Platinum has been increasing in the environment as a result of emissions from catalytic converters. The platinum emitted is principally located in the vicinity of roads but might be transported to urban rivers through highway and urban run-off water. Platinum concentrations in the freshwater isopod Asellus aquaticus were measured for two urban rivers and a stormwater detention pond. Concentrations ranged from 0.04 to 12.4 {mu}g g{sup -1} for direct analysis and from 0.16 to 4.5 {mu}g g{sup -1} after depuration. Analyses of water, pore water and sediments indicate that platinum in urban rivers is mostly found in the sediments and these provide the major contribution of platinum to Asellus aquaticus. Exposure experiments showed the importance of platinum speciation for uptake.

  19. Synthesis of platinum nanowire networks using a soft template.

    Science.gov (United States)

    Song, Yujiang; Garcia, Robert M; Dorin, Rachel M; Wang, Haorong; Qiu, Yan; Coker, Eric N; Steen, William A; Miller, James E; Shelnutt, John A

    2007-12-01

    Platinum nanowire networks have been synthesized by chemical reduction of a platinum complex using sodium borohydride in the presence of a soft template formed by cetyltrimethylammonium bromide in a two-phase water-chloroform system. The interconnected polycrystalline nanowires possess the highest surface area (53 +/- 1 m2/g) and electroactive surface area (32.4 +/- 3.6 m2/g) reported for unsupported platinum nanomaterials; the high surface area results from the small average diameter of the nanowires (2.2 nm) and the 2-10 nm pores determined by nitrogen adsorption measurements. Synthetic control over the network was achieved simply by varying the stirring rate and reagent concentrations, in some cases leading to other types of nanostructures including wormlike platinum nanoparticles. Similarly, substitution of a palladium complex for platinum gives palladium nanowire networks. A mechanism of formation of the metal nanowire networks is proposed based on confined metal growth within a soft template consisting of a network of swollen inverse wormlike micelles.

  20. Synthesis of platinum nanowheels using a bicellar template.

    Science.gov (United States)

    Song, Yujiang; Dorin, Rachel M; Garcia, Robert M; Jiang, Ying-Bing; Wang, Haorong; Li, Peng; Qiu, Yan; van Swol, Frank; Miller, James E; Shelnutt, John A

    2008-09-24

    Disk-like surfactant bicelles provide a unique meso-structured reaction environment for templating the wet-chemical reduction of platinum(II) salt by ascorbic acid to produce platinum nanowheels. The Pt wheels are 496 +/-55 nm in diameter and possess thickened centers and radial dendritic nanosheets (about 2-nm in thickness) culminating in flared dendritic rims. The structural features of the platinum wheels arise from confined growth of platinum within the bilayer that is also limited at edges of the bicelles. The size of CTAB/FC7 bicelles is observed to evolve with the addition of Pt(II) complex and ascorbic acid. Synthetic control is demonstrated by varying the reaction parameters including metal salt concentration, temperature, and total surfactant concentration. This study opens up opportunities for the use of other inhomogeneous soft templates for synthesizing metals, metal alloys, and possibly semiconductors with complex nanostructures.

  1. Advancing viral RNA structure prediction: measuring the thermodynamics of pyrimidine-rich internal loops.

    Science.gov (United States)

    Phan, Andy; Mailey, Katherine; Saeki, Jessica; Gu, Xiaobo; Schroeder, Susan J

    2017-05-01

    Accurate thermodynamic parameters improve RNA structure predictions and thus accelerate understanding of RNA function and the identification of RNA drug binding sites. Many viral RNA structures, such as internal ribosome entry sites, have internal loops and bulges that are potential drug target sites. Current models used to predict internal loops are biased toward small, symmetric purine loops, and thus poorly predict asymmetric, pyrimidine-rich loops with >6 nucleotides (nt) that occur frequently in viral RNA. This article presents new thermodynamic data for 40 pyrimidine loops, many of which can form UU or protonated CC base pairs. Uracil and protonated cytosine base pairs stabilize asymmetric internal loops. Accurate prediction rules are presented that account for all thermodynamic measurements of RNA asymmetric internal loops. New loop initiation terms for loops with >6 nt are presented that do not follow previous assumptions that increasing asymmetry destabilizes loops. Since the last 2004 update, 126 new loops with asymmetry or sizes greater than 2 × 2 have been measured. These new measurements significantly deepen and diversify the thermodynamic database for RNA. These results will help better predict internal loops that are larger, pyrimidine-rich, and occur within viral structures such as internal ribosome entry sites. © 2017 Phan et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  2. Inhibition of cyclobutane pyrimidine dimer formation in epidermal p53 gene of UV-irradiated mice by alpha-tocopherol

    International Nuclear Information System (INIS)

    Chen, W.; Barthelman, M.; Martinez, J.; Alberts, D.; Gensler, H.L.

    1997-01-01

    Mutations or alterations in the p53 gene have been observed in 50-100% of ultraviolet light (UV)-induced squamous cell carcinoma in humans and animals. Most of the mutations occurred at dipyrimidine sequences, suggesting that pyrimidine dimers in the p53 gene play a role in the pathogenesis of cutaneous squamous cell carcinoma. We previously showed that topical alpha-tocopherol prevents UV-induced skin carcinogenesis in the mouse. In the present study we asked whether topical alpha-tocopherol reduces the level of UV-induced cyclobutane pyrimidine dimers in the murine epidermal p53 gene. Mice received six dorsal applications of 25 mg each of alpha-tocopherol, on alternate days, before exposure to 500 J/m2 of UV-B irradiation. Mice were killed at selected times after irradiation. The level of dimers in the epidermal p53 gene was measured using the T4 endonuclease V assay with quantitative Southern hybridization. Topical alpha-tocopherol caused a 55% reduction in the formation of cyclobutane pyrimidine dimers in the epidermal p53 gene. The rate of reduction of pyrimidine dimers between 1 and 10 hours after irradiation was similar in UV-irradiated mice, regardless of alpha-tocopherol treatment. Therefore, the lower level of cyclobutane pyrimidine dimers in UV-irradiated mice treated with alpha-tocopherol than in control UV-irradiated mice resulted from the prevention of formation of the dimers, and not from enhanced repair of these lesions. Our results indicate that alpha-tocopherol acts as an effective sunscreen in vivo, preventing the formation of premutagenic DNA lesions in a gene known to be important in skin carcinogenesis

  3. The role of pyrimidine and water as underlying molecular constituents for describing radiation damage in living tissue: A comparative study

    Energy Technology Data Exchange (ETDEWEB)

    Fuss, M. C.; Ellis-Gibbings, L. [Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas (CSIC), Serrano 113-bis, 28006 Madrid (Spain); Jones, D. B. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Brunger, M. J. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Institute of Mathematical Sciences, University of Malaya, 50603 Kuala Lumpur (Malaysia); Blanco, F. [Departamento de Física Atómica, Molecular y Nuclear, Universidad Complutense de Madrid, Avenida Complutense, 28040 Madrid (Spain); Muñoz, A. [Centro de Investigaciones Energéticas Medioambientales y Tecnológicas, Avenida Complutense 22, 28040 Madrid (Spain); Limão-Vieira, P. [School of Chemical and Physical Sciences, Flinders University, GPO Box 2100, Adelaide, South Australia 5001 (Australia); Laboratório de Colisões Atómicas e Moleculares, CEFITEC, Departamento de Física, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica (Portugal); García, G., E-mail: g.garcia@csic.es [Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas (CSIC), Serrano 113-bis, 28006 Madrid (Spain); Centre for Medical Radiation Physics, University of Wollongong, Wollongong, NSW 2522 (Australia)

    2015-06-07

    Water is often used as the medium for characterizing the effects of radiation on living tissue. However, in this study, charged-particle track simulations are employed to quantify the induced physicochemical and potential biological implications when a primary ionising particle with energy 10 keV strikes a medium made up entirely of water or pyrimidine. Note that pyrimidine was chosen as the DNA/RNA bases cytosine, thymine, and uracil can be considered pyrimidine derivatives. This study aims to assess the influence of the choice of medium on the charged-particle transport, and identify how appropriate it is to use water as the default medium to describe the effects of ionising radiation on living tissue. Based on the respective electron interaction cross sections, we provide a model, which allows the study of radiation effects not only in terms of energy deposition (absorbed dose and stopping power) but also in terms of the number of induced molecular processes. Results of these parameters for water and pyrimidine are presented and compared.

  4. (3,5-Dimethylpyrazol-1-yl-[4-(1-phenyl-1H-pyrazolo[3,4-d]pyrimidin-4-ylaminophenyl]methanone

    Directory of Open Access Journals (Sweden)

    Rania B. Bakr

    2016-11-01

    Full Text Available In an attempt to enhance cytotoxic activity of pyrazolo[3,4-d]pyrimidine core, we synthesized (3,5-dimethylpyrazol-1-yl-[4-(1-phenyl-1H-pyrazolo[3,4-d]pyrimidin-4-ylaminophenyl]methanone (4 by reacting 4-(1-phenyl-1H-pyrazolo[3,4-d]pyrimidin-4-ylaminobenzohydrazide (3 with acetylacetone. Antiproliferative activity of this compound was screened against breast (MCF-7, colon (HCT-116, and liver (HEPG-2 cancer cell lines. The tested compound exhibited cytotoxic activity with IC50 = 5.00–32.52 μM. Moreover, inhibitory activity of this compound was evaluated against the epidermal growth factor receptor (EGFR, the fibroblast growth factor receptor (FGFR, the insulin receptor (IR, and the vascular endothelial growth factor receptor (VEGFR. This target compound showed potent inhibitory activity, especially against FGFR with IC50 = 5.18 μM.

  5. Analysis of pyrimidine synthesis "de novo" intermediates in urine and dried urine filter- paper strips with HPLC-electrospray tandem mass spectrometry

    NARCIS (Netherlands)

    van Kuilenburg, André B. P.; van Lenthe, Henk; Löffler, Monika; van Gennip, Albert H.

    2004-01-01

    BACKGROUND: The concentrations of the pyrimidine "de novo" metabolites and their degradation products in urine are useful indicators for the diagnosis of an inborn error of the pyrimidine de novo pathway or a urea-cycle defect. Until now, no procedure was available that allowed the analysis of all

  6. Differences in pyrimidine dimer removal between rat skin cells in vitro and in vivo

    International Nuclear Information System (INIS)

    Mullaart, E.; Lohman, P.H.; Vijg, J.

    1988-01-01

    Pyrimidine dimers, the most abundant type of DNA lesions induced by ultraviolet light (UV), are rapidly repaired in human skin fibroblasts in vitro. In the same cell type from rats, however, there is hardly any removal of such dimers. To investigate whether this low capacity of rat skin cells to repair lesions in their DNA is an inherent characteristic of this species or an artifact due to cell culturing, we measured the removal of UV-induced pyrimidine dimers from rat epidermal keratinocytes both in vitro and in vivo. Epidermal keratinocytes in vitro were unable to remove any dimers over the first 3 h after UV-irradiation, while only about 20% was removed during a repair period of 24 h. In this respect, these cells were not different from cultured rat fibroblasts. In contrast to the results obtained with keratinocytes in vitro, we observed a rapid repair of pyrimidine dimers in UV-irradiated keratinocytes in vivo over the first 3 h; this rapid repair phase was followed by a much slower repair phase between 3 and 24 h. These results are discussed in terms of the possibility that mammalian cells are able to switch from one DNA repair pathway to another

  7. A Change to the Platinum Publications | Poster

    Science.gov (United States)

    Please be advised that the Poster will no longer publish the “Platinum Publications” series listing recent NCI at Frederick publications. All published research represents a valuable addition to the fight against cancer, AIDS, and infectious diseases—thus, the “Platinum Publications” did not adequately commend all of the important work done by NCI at Frederick researchers.

  8. Dissolution of Platinum in Hydrochloric Acid Under Industrial-Scale Alternating Current Polarization

    Science.gov (United States)

    Myrzabekov, B. E.; Bayeshov, A. B.; Makhanbetov, A. B.; Mishra, B.; Baigenzhenov, O. S.

    2018-02-01

    The electrochemical behavior of platinum in a hydrochloric acid solution under polarization by an industrial-scale alternating current has been investigated. For the electrical dissolution of platinum, titanium is used as an auxiliary electrode, which increases the yield of platinum dissolution by 12.5 pct. The influence of the concentration of hydrochloric acid, the current densities of the platinum and titanium electrodes, and the temperature of the electrolyte on the efficiency of the process of dissolving platinum have all been studied.

  9. Environmental Perceptions and Health before and after Relocation to a Green Building.

    Science.gov (United States)

    MacNaughton, Piers; Spengler, John; Vallarino, Jose; Santanam, Suresh; Satish, Usha; Allen, Joseph

    2016-08-01

    Green buildings are designed to have low environmental impacts and improved occupant health and well-being. Improvements to the built environment including ventilation, lighting, and materials have resulted in improved indoor environmental quality (IEQ) in green buildings, but the evidence around occupant health is currently centered around environmental perceptions and self-reported health. To investigate the objective impact of green buildings on health, we tracked IEQ, self-reported health, and heart rate in 30 participants from green and conventional buildings for two weeks. 24 participants were then selected to be relocated to the Syracuse Center of Excellence, a LEED platinum building, for six workdays. While they were there, ventilation, CO 2 , and volatile organic compound (VOC) levels were changed on different days to match the IEQ of conventional, green, and green+ (green with increased ventilation) buildings. Participants reported improved air quality, odors, thermal comfort, ergonomics, noise and lighting and fewer health symptoms in green buildings prior to relocation. After relocation, participants consistently reported fewer symptoms during the green building conditions compared to the conventional one, yet symptom counts were more closely associated with environmental perceptions than with measured IEQ. On average, participants had 4.7 times the odds of reporting a lack of air movement, 1.4 more symptoms (p-value = 0.019) and a 2 bpm higher heart rate (p-value green and conventional buildings is driven by both environmental perceptions and physiological pathways.

  10. Inwerking van stikstofhoudende nucleofielen op enige 15N-gemerkte pyrimidine- en chinazolinederivaten

    NARCIS (Netherlands)

    Kroon, A.P.

    1974-01-01

    In this thesis an investigation is described on the mechanism of aminations of pyrimidine- and quinazoline derivatives with nitrogen containing bases.

    In the introduction a survey is given of investigations, reported in the literature, concerning σ-complex formation on azahetarenes and their

  11. Preparation of platinum/iridium scanning probe microscopy tips

    DEFF Research Database (Denmark)

    Sørensen, Alexis Hammer; Hvid, U.; Mortensen, M.W.

    1999-01-01

    oxide layer. In order to explain the relatively high etching rates observed for the otherwise noble metal platinum we suggest that besides anodic corrosion of the platinum by the electrolyte containing chloride ions, a different etching mechanism causes a substantial increase of the etching rate...

  12. Absorption and Intermediary Metabolism of Purines and Pyrimidines in Lactating Dairy Cows

    DEFF Research Database (Denmark)

    Nielsen, Charlotte Stentoft; Røjen, Betina Amdisen; Jensen, Søren Krogh

    2015-01-01

    About 20 % of ruminal microbial N in dairy cows derives from purines and pyrimidines; however, their intermediary metabolism and contribution to the overall N metabolism has sparsely been described. In the present study, the postprandial patterns of net portal-drained viscera (PDV) and hepatic...

  13. Exosomes as mediators of platinum resistance in ovarian cancer.

    Science.gov (United States)

    Crow, Jennifer; Atay, Safinur; Banskota, Samagya; Artale, Brittany; Schmitt, Sarah; Godwin, Andrew K

    2017-02-14

    Exosomes have been implicated in the cell-cell transfer of oncogenic proteins and genetic material. We speculated this may be one mechanism by which an intrinsically platinum-resistant population of epithelial ovarian cancer (EOC) cells imparts its influence on surrounding tumor cells. To explore this possibility we utilized a platinum-sensitive cell line, A2780 and exosomes derived from its resistant subclones, and an unselected, platinum-resistant EOC line, OVCAR10. A2780 cells demonstrate a ~2-fold increase in viability upon treatment with carboplatin when pre-exposed to exosomes from platinum-resistant cells as compared to controls. This coincided with increased epithelial to mesenchymal transition (EMT). DNA sequencing of EOC cell lines revealed previously unreported somatic mutations in the Mothers Against Decapentaplegic Homolog 4 (SMAD4) within platinum-resistant cells. A2780 cells engineered to exogenously express these SMAD4 mutations demonstrate up-regulation of EMT markers following carboplatin treatment, are more resistant to carboplatin, and release exosomes which impart a ~1.7-fold increase in resistance in naive A2780 recipient cells as compared to controls. These studies provide the first evidence that acquired SMAD4 mutations enhance the chemo-resistance profile of EOC and present a novel mechanism in which exchange of tumor-derived exosomes perpetuates an EMT phenotype, leading to the development of subpopulations of platinum-refractory cells.

  14. One-step electrochemically-codeposited polyaniline-platinum for dye-sensitized solar cell applications

    Energy Technology Data Exchange (ETDEWEB)

    Thiangkaew, Anongnad; Keothongkham, Khamsone; Maiaugree, Wasan; Jarernboon, Wirat [Khon Kaen University, Khon Kaen (Thailand); Kamwanna, Teerasak; Pimanpang, Samuk; Amornkitbamrung, Vittaya [Khon Kaen University, Khon Kaen (Thailand); Nanotec-KKU Center of Excellence on Advanced Nanomaterials for Energy Production and Storage, Khon Kaen (Thailand)

    2014-05-15

    Platinum, polyaniline and composite polyaniline-platinum films were coated on conductive glass by using electrochemical deposition. They were then used as dye-sensitized solar cell counter electrodes. The efficiencies of platinum, polyaniline and composite polyaniline-platinum cells were 2.47, 4.47 and 6.62%, respectively. The improvement of composite polyaniline-platinum solar cell efficiency over pure polyaniline and platinum cells is because of an increase in the film's catalytic activity and a decrease in charge-transfer resistance between its counter electrode and electrolyte, as observed by using cyclic voltammogram and electrochemical impedance spectroscopy measurements, respectively. Co-deposition of polyaniline and Pt catalysts was confirmed by the presence of Pt and N peaks in the X-ray photoelectron spectroscopy spectrum.

  15. Phase-field model for deposition process of platinum nanoparticles on carbon substrate

    International Nuclear Information System (INIS)

    Yamakawa, S; Hyodo, S; Okazaki-Maeda, K; Kohyama, M

    2008-01-01

    Platinum supported on a carbon carrier is widely used as a catalyst for polymer electrolyte membrane fuel cells. The catalytic activity is significantly affected by the size distribution and morphologies of the platinum particles. The objective of this study is to extend the phase-field approach to describe the formation process of platinum particles onto the substrate. The microstructural evolution of a nanoparticle was represented by the temporal evolution of the field variables related to the platinum concentration, long-range crystallographic ordering and phase transition. First-principles calculations were performed in order to estimate the interaction energies between several different types of platinum clusters and a graphene sheet. The platinum density profile concentrated over the substrate surface led to the formation of three-dimensional islands in accordance with the Volmer-Weber mode of growth. The size distributions of the platinum particles were sensitive to the heterogeneity of the substrate surface and to the competitive nucleation and growth processes

  16. An impending platinum crisis and its implications for the future of the automobile

    International Nuclear Information System (INIS)

    Yang, C.-J.

    2009-01-01

    The global demand for platinum has consistently outgrown supply in the past decade. This trend likely will continue and the imbalance may possibly escalate into a crisis. Platinum plays pivotal roles in both conventional automobile emissions control and the envisioned hydrogen economy. A platinum crisis would have profound implications on energy and environment. On the one hand, inadequate platinum supply will prevent widespread commercialization of hydrogen fuel-cell vehicles. On the other hand, expensive platinum may enhance the competitiveness of hybrid, plug-in hybrid, and battery-powered electric cars. Policymakers should weigh the potential impacts of a platinum crisis in energy policy.

  17. Photophysics of organometallic platinum(II) derivatives of the diketopyrrolopyrrole chromophore

    KAUST Repository

    Goswami, Subhadip; Winkel, Russell W.; Alarousu, Erkki; Ghiviriga, Ion; Mohammed, Omar F.; Schanze, Kirk S.

    2014-01-01

    A pair of diketopyrrolopyrrole (DPP) chromophores that are end-functionalized with platinum containing "auxochromes" were subjected to electrochemical and photophysical study. The chromophores contain either platinum acetylide or ortho-metalated 2-thienylpyridinyl(platinum) end-groups (DPP-Pt(CC) and DPP-Pt(acac), respectively). The ground state redox potentials of the chromophores were determined by solution electrochemistry, and the HOMO and LUMO levels were estimated. The chromophores' photophysical properties were characterized by absorption, photoluminescence, and time-resolved absorption spectroscopy on time scales from sub-picoseconds to microseconds. Density functional theory (DFT) computations were performed to understand the molecular orbitals involved in both the singlet and triplet excited state photophysics. The results reveal that in both platinum DPP derivatives the organometallic auxochromes have a significant effect on the chromophores' photophysics. The most profound effect is a reduction in the fluorescence yields accompanied by enhanced triplet yields due to spin-orbit coupling induced by the metal centers. The effects are most pronounced in DPP-Pt(acac), indicating that the orthometalated platinum auxochrome is able to induce spin-orbital coupling to a greater extent compared to the platinum acetylide units. (Figure Presented).

  18. In vitro permeation of platinum and rhodium through Caucasian skin.

    Science.gov (United States)

    Franken, A; Eloff, F C; Du Plessis, J; Badenhorst, C J; Jordaan, A; Du Plessis, J L

    2014-12-01

    During platinum group metals (PGMs) refining the possibility exists for dermal exposure to PGM salts. The dermal route has been questioned as an alternative route of exposure that could contribute to employee sensitisation, even though literature has been focused on respiratory exposure. This study aimed to investigate the in vitro permeation of platinum and rhodium through intact Caucasian skin. A donor solution of 0.3mg/ml of metal, K2PtCl4 and RhCl3 respectively, was applied to the vertical Franz diffusion cells with full thickness abdominal skin. The receptor solution was removed at various intervals during the 24h experiment, and analysed with high resolution ICP-MS. Skin was digested and analysed by ICP-OES. Results indicated cumulative permeation with prolonged exposure, with a significantly higher mass of platinum permeating after 24h when compared to rhodium. The mass of platinum retained inside the skin and the flux of platinum across the skin was significantly higher than that of rhodium. Permeated and skin retained platinum and rhodium may therefore contribute to sensitisation and indicates a health risk associated with dermal exposure in the workplace. Copyright © 2014 Elsevier Ltd. All rights reserved.

  19. Photophysics of organometallic platinum(II) derivatives of the diketopyrrolopyrrole chromophore

    KAUST Repository

    Goswami, Subhadip

    2014-12-18

    A pair of diketopyrrolopyrrole (DPP) chromophores that are end-functionalized with platinum containing "auxochromes" were subjected to electrochemical and photophysical study. The chromophores contain either platinum acetylide or ortho-metalated 2-thienylpyridinyl(platinum) end-groups (DPP-Pt(CC) and DPP-Pt(acac), respectively). The ground state redox potentials of the chromophores were determined by solution electrochemistry, and the HOMO and LUMO levels were estimated. The chromophores\\' photophysical properties were characterized by absorption, photoluminescence, and time-resolved absorption spectroscopy on time scales from sub-picoseconds to microseconds. Density functional theory (DFT) computations were performed to understand the molecular orbitals involved in both the singlet and triplet excited state photophysics. The results reveal that in both platinum DPP derivatives the organometallic auxochromes have a significant effect on the chromophores\\' photophysics. The most profound effect is a reduction in the fluorescence yields accompanied by enhanced triplet yields due to spin-orbit coupling induced by the metal centers. The effects are most pronounced in DPP-Pt(acac), indicating that the orthometalated platinum auxochrome is able to induce spin-orbital coupling to a greater extent compared to the platinum acetylide units. (Figure Presented).

  20. In vivo excision of pyrimidine dimers is mediated by a DNA N-glycosylase in Micrococcus luteus but not in human fibroblasts

    International Nuclear Information System (INIS)

    La Belle, M.; Linn, S.

    1982-01-01

    It has been previously shown that Micrococcus luteus possesses a pyrimidine dimer-specific endonuclease which in vitro, functions as both an endonuclease and DNA-glycosylase. To determine if these combined activities function in vivo, the excision products of UV-irradiated M. luteus were isolated and examined. In addition, a procedure was devised to isolate and examine the excision products from UV-irradiated human fibroblasts to determine if an endonuclease/glycosylase activity functions in the excision of UV-induced pyrimidine dimers in human fibroblasts. It was shown that, in vivo, an endonuclease/glycosylase mechanism is utilized extensively in the repair of pyrimidine dimers by M. luteus, but that human fibroblasts do not appear to use this mechanism. (author)

  1. In vivo excision of pyrimidine dimers is mediated by a DNA N-glycosylase in Micrococcus luteus but not in human fibroblasts

    Energy Technology Data Exchange (ETDEWEB)

    La Belle, M; Linn, S [California Univ., Berkeley (USA). Dept. of Biochemistry

    1982-09-01

    It has been previously shown that Micrococcus luteus possesses a pyrimidine dimer-specific endonuclease which in vitro, functions as both an endonuclease and DNA-glycosylase. To determine if these combined activities function in vivo, the excision products of UV-irradiated M. luteus were isolated and examined. In addition, a procedure was devised to isolate and examine the excision products from UV-irradiated human fibroblasts to determine if an endonuclease/glycosylase activity functions in the excision of UV-induced pyrimidine dimers in human fibroblasts. It was shown that, in vivo, an endonuclease/glycosylase mechanism is utilized extensively in the repair of pyrimidine dimers by M. luteus, but that human fibroblasts do not appear to use this mechanism.

  2. Platinum boride nanowires: Synthesis and characterization

    International Nuclear Information System (INIS)

    Ding Zhanhui; Qiu Lixia; Zhang Jian; Yao Bin; Cui Tian; Guan Weiming; Zheng Weitao; Wang Wenquan; Zhao Xudong; Liu Xiaoyang

    2012-01-01

    Highlights: ► Platinum boride nanowires have been synthesized via the direct current arc discharge method. ► XRD, TEM and SAED indicate that the nanowires are single-crystal PtB. ► Two broad photoluminescence emission peaks at about 586 nm and 626 nm have been observed in the PL spectroscopy of PtB nanowires. - Abstract: Platinum boride (PtB) nanowires have been successfully fabricated with direct current arc discharge method using a milled mixture of platinum (Pt) and boron nitride (BN) powders. X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to characterize the compositions, morphology, and structures of the samples. The results show that PtB nanowires are 30–50 nm thick and 20–30 μm long. TEM and selected area electron diffraction (SAED) patterns identify that the PtB nanowires are single-crystalline in nature. A growth mechanism based on vapor–liquid–solid (VLS) process is proposed for the formation of nanowires.

  3. Urinary excretion of platinum, arsenic and selenium of cancer patients from the Antofagasta region in Chile treated with platinum-based drugs

    Directory of Open Access Journals (Sweden)

    Román Domingo A

    2012-04-01

    Full Text Available Abstract Background Arsenic exposure increases the risk of non-cancerous and cancerous diseases. In the Antofagasta region in Chile, an established relationship exists between arsenic exposure and the risk of cancer of the bladder, lung and skin. Platinum-based drugs are first-line treatments, and many works recognise selenium as a cancer-fighting nutrient. We characterised the short-term urinary excretion amounts of arsenic, selenium and platinum in 24-h urine samples from patients with lung cancer and those with cancer other than lung treated with cisplatin or/and carboplatin. As - Se - Pt inter-element relationships were also investigated. Results The amounts of platinum excreted in urine were not significantly different between patients with lung cancer and those with other cancers treated with cisplatin, despite the significant variation in platinum amounts supplied from platinum-based drugs. In general, the analytical amounts of excreted selenium were greater than those for arsenic, which could imply that platinum favours the excretion of selenium. For other types of cancers treated with drugs without platinum, excretion of selenium was also greater than that of arsenic, suggesting an antagonist selenium-anti-cancer drug relationship. Conclusions Regards the baseline status of patients, the analytical amounts of excreted Se is greater than those for As, particularly, for cisplatin chemotherapy. This finding could imply that for over the As displacement Pt favours the excretion of Se. The analytical amounts of excreted Se were greater than those for As, either with and without Pt-containing drugs, suggesting an antagonist Se-anti-cancer drug relationship. However, it seemed that differences existed between As - Se - Pt inter-element associations in patients treated for lung cancer in comparison with those treated for cancer other than lung. Therefore, knowledge obtained in this work, can contribute to understanding the arsenic cancer

  4. Purification, crystallization and preliminary X-ray diffraction study on pyrimidine nucleoside phosphorylase TTHA1771 from Thermus thermophilus HB8

    International Nuclear Information System (INIS)

    Shimizu, Katsumi; Kunishima, Naoki

    2007-01-01

    The pyrimidine nucleoside phosphorylase TTHA1771 from T. thermophilus HB8 has been overexpressed, purified and crystallized. The crystals diffract X-rays to 1.8 Å resolution using synchrotron radiation. Pyrimidine nucleoside phosphorylase (PYNP) catalyzes the reversible phosphorolysis of pyrimidines in the nucleotide-synthesis salvage pathway. In order to study the structure–thermostability relationship of this enzyme, PYNP from the extreme thermophile Thermus thermophilus HB8 (TTHA1771) has been cloned, overexpressed and purified. The TTHA1771 protein was crystallized at 291 K using the oil-microbatch method with PEG 4000 as a precipitant. A native data set was collected to 1.8 Å resolution using synchrotron radiation. The crystal belongs to the monoclinic space group P2 1 , with unit-cell parameters a = 58.83, b = 76.23, c = 103.86 Å, β = 91.3°

  5. Comparison of the cleavage of pyrimidine dimers by the bacteriophage T4 and Micrococcus luteus uv-specific endonucleases

    International Nuclear Information System (INIS)

    Gordon, L.K.; Haseltine, W.A.

    1980-01-01

    A comparison was made of the activity of the uv-specific endonucleases of bacteriophage T4 (T4 endonuclease V) and of Micrococcus luteus on ultraviolet light-irradiated DNA substrates of defined sequence. The two enzyms cleave DNA at the site of pyrimidine dimers with the same frequency. The products of the cleavage reaction are the same. The pyrimidine dimer DNA-glycosylase activity of both enzymes is more active on double-stranded DNA than it is on single-stranded DNA

  6. Electrical Discharge Platinum Machining Optimization Using Stefan Problem Solutions

    Directory of Open Access Journals (Sweden)

    I. B. Stavitskiy

    2015-01-01

    Full Text Available The article presents the theoretical study results of platinum workability by electrical discharge machining (EDM, based on the solution of the thermal problem of moving the boundary of material change phase, i.e. Stefan problem. The problem solution enables defining the surface melt penetration of the material under the heat flow proceeding from the time of its action and the physical properties of the processed material. To determine the rational EDM operating conditions of platinum the article suggests relating its workability with machinability of materials, for which the rational EDM operating conditions are, currently, defined. It is shown that at low densities of the heat flow corresponding to the finishing EDM operating conditions, the processing conditions used for steel 45 are appropriate for platinum machining; with EDM at higher heat flow densities (e.g. 50 GW / m2 for this purpose copper processing conditions are used; at the high heat flow densities corresponding to heavy roughing EDM it is reasonable to use tungsten processing conditions. The article also represents how the minimum width of the current pulses, at which platinum starts melting and, accordingly, the EDM process becomes possible, depends on the heat flow density. It is shown that the processing of platinum is expedient at a pulse width corresponding to the values, called the effective pulse width. Exceeding these values does not lead to a substantial increase in removal of material per pulse, but considerably reduces the maximum repetition rate and therefore, the EDM capacity. The paper shows the effective pulse width versus the heat flow density. It also presents the dependences of the maximum platinum surface melt penetration and the corresponding pulse width on the heat flow density. Results obtained using solutions of the Stephen heat problem can be used to optimize EDM operating conditions of platinum machining.

  7. An unusual correlation between ppGpp pool size and rate of ribosome synthesis during partial pyrimidine starvation of Escherichia coli

    DEFF Research Database (Denmark)

    Vogel, Ulla; Pedersen, Steen; Jensen, Kaj Frank

    1991-01-01

    Escherichia coli was exposed to partial pyrimidine starvation by feeding a pyrBI strain orotate as the only pyrimidine source. Subsequently, differential rates of synthesis of rRNA and of a few ribosome-associated proteins as well as the pool sizes of nucleoside triphosphates and ppGpp were measu...

  8. The RSC Faraday prize lecture of 1989 on platinum.

    Science.gov (United States)

    Thomas, John Meurig

    2017-08-25

    In 1861, Michael Faraday gave one of his last Friday Evening Discourses at the Royal Institution of Great Britain, London, on platinum, which he described as "this beautiful, magnificent and valuable metal". More than a hundred and twenty years later (in 1989), the author re-enacted, at the Royal Institution, many of the demonstrations that Faraday carried out in his memorable Discourse. This article outlines many of Faraday's views on, and experiments with, platinum. It also describes the continuing importance and utilization of platinum, both as perceived in 1989 and from present perspectives.

  9. Preconcentration and Extraction of Copper ion on Activated Carbon using α-Benzoinoxime and Pyrimidin 2-Thiole

    International Nuclear Information System (INIS)

    Ghaedi, M.; Mortazavi, K.; Janbezar, M.; Parham, H.

    2006-01-01

    Activated carbon modified methods were used for preconcentration and determination of copper in some real sample by flame atomic absorption spectrometry. The copper was adsorbed quantitatively on activated carbon due to their complexation with α-benzoinoxime and pyrimidin 2-thiole. The adsorbed copper on solid phase was eluted quantitatively using nitric acid. The important parameters such as pH, amount of carrier, flow rate, amount of activated carbon and type and concentration of eluting agent for obtaining maximum recovery was optimized. The methods based on α- benzoinoxime and pyrimidin 2-thiole at optimum conditions is linear over concentration range of 0.05-1.3 ug mL and 0.06-1.2 ug mL of copper with correlation coefficient of 0.9997 and 0.9994 and both detection limit of 1.2 ngmL, respectively. The preconcentration leads to enrichment factor of 200 and 240 and break through volume of 1200 mL for methods based on α- benzoinoxime and pyrimidin 2-thiole, respectively. The methods have good tolerance limit of interfering ion and selectivity that has been successfully applied for determination of copper content in real sample such as blood, wastewater and river sample. (author)

  10. Microwave-Assisted Synthesis and Antimicrobial Evaluation of Novel Spiroisoquinoline and Spiropyrido[4,3-d]pyrimidine Derivatives

    Directory of Open Access Journals (Sweden)

    Rasha M. Faty

    2015-01-01

    Full Text Available Bromination of N-substituted homophthalimides and tetrahydropyrido[4,3-d]- pyrimidine-5,7-diones produces 4,4-dibromohomophthalimide and 8,8-dibromo-tetrahydropyrido[4,3-d]pyrimidine-5,7-dione derivatives, respectively, that can be used as precursors for spiro derivatives. The dibromo derivatives react with different binucleophilic reagents to produce several spiroisoquinoline and spirotetrahydropyrido[4,3-d]- pyrimidine-5,7-dione derivatives, respectively. Reaction of the dibromo derivatives with malononitrile produces dicyanomethylene derivatives which react with different binucleophiles to produce new spiro derivatives. All new compounds are prepared by using the usual chemical conditions and microwave assisted conditions. The latter conditions improved the reaction yields, reduced reaction times and ameliorated the effects on the surrounding environment as the reactions are carried out in closed systems. Structures of the newly synthesized compounds are proved using spectroscopic methods such as IR, MS, 1H-NMR and 13C-NMR and elemental analyses. Some of the newly synthesized compounds were tested for their antimicrobial activities, whereby four of them showed moderate activities and the rest showed low or no activities towards the investigated species.

  11. Photorepair and excision repair removal of UV-induced pyrimidine dimers and (6-4) photoproducts in the tail fin of the Medaka, Oryzias latipes

    International Nuclear Information System (INIS)

    Funayama, Tomoo; Mitani, Hiroshi; Shima, Akihiro; Ishigaki, Yasuhito; Matsunaga, Tsukasa; Nikaido, Osamu.

    1994-01-01

    Induction and repair of UV-B induced DNA damage in the tail fin of the Medaka, were examined immunohistochemically and by the enzyme-linked immunosorbent assay (ELISA). UV-induced DNA damage was detected only in the outermost layer of epithelial cells and did not differ in fishes having different degree of melanization. Both pyrimidine dimers and (6-4) photoproducts in the fin cells were removed by excision repair in the dark, the excision of (6-4) photoproducts being about twice as efficient as that of pyrimidine dimers. The rate of excision repair of UV-induced lesions in fin tissue was three to four times that in cultured Medaka cells, OL32.. In the fin cells, reductions in the numbers of pyrimidine dimers and (6-4) photoproducts were seen after treatment with fluorescent light, whereas less reductions of pyrimidine dimers and no reductions of (6-4) photoproducts were observed in OL32 cells. (author)

  12. Comparative studies on the correlation between pyrimidine dimer formation and tyrosinase activity in Cloudman S91 melanoma cells after ultraviolet-irradiation

    International Nuclear Information System (INIS)

    Niggli, H.J.

    1990-01-01

    The authors compared the induction of pyrimidine dimer densities after UV-irradiation in mouse melanoma cells before and after treatment with cholera toxin. Treatment with cholera toxin stimulated tyrosinase activity up to 50-fold, leading to a marked, visually apparent increase in cellular melanin concentrations. Results indicate that de novo melanin pigmentation induced via the c-AMP pathway is not involved in protection against UV-induced thymine-containing pyrimidine dimers. In separate experiments, irradiation of toxin-treated and untreated mouse melanoma cells with UVC or UVB light produced a 20-30% lower dimer density compared to irradiated human skin fibroblasts. This finding suggests that melanin has some protection properties against UV-induced pyrimidine dimers, although the exact defense mechanism seems highly complex. (author)

  13. Tumour radiosensitization with the halogenated pyrimidines 5'-bromo-and 5'-iododeoxyuridine

    Energy Technology Data Exchange (ETDEWEB)

    Epstein, A.H.; Cook, J.A.; Goffman, T. (National Cancer Inst., Bethesda, MD (United States)); Glatstein, E. (Texas Univ., Dallas, TX (United States). Southwestern Medical Center)

    1993-02-01

    The authors review studies of the use of iododeoxyuridine (IdUrd) and bromodeoxyuridine as radiosensitizers and attempt to correlate the clinical outcome for patients treated with radiation and IdUrd with the extent of halogenated pyrimidine cellular uptake and incorporation. (U.K.).

  14. Single-Atom Catalyst of Platinum Supported on Titanium Nitride for Selective Electrochemical Reactions.

    Science.gov (United States)

    Yang, Sungeun; Kim, Jiwhan; Tak, Young Joo; Soon, Aloysius; Lee, Hyunjoo

    2016-02-05

    As a catalyst, single-atom platinum may provide an ideal structure for platinum minimization. Herein, a single-atom catalyst of platinum supported on titanium nitride nanoparticles were successfully prepared with the aid of chlorine ligands. Unlike platinum nanoparticles, the single-atom active sites predominantly produced hydrogen peroxide in the electrochemical oxygen reduction with the highest mass activity reported so far. The electrocatalytic oxidation of small organic molecules, such as formic acid and methanol, also exhibited unique selectivity on the single-atom platinum catalyst. A lack of platinum ensemble sites changed the reaction pathway for the oxygen-reduction reaction toward a two-electron pathway and formic acid oxidation toward direct dehydrogenation, and also induced no activity for the methanol oxidation. This work demonstrates that single-atom platinum can be an efficient electrocatalyst with high mass activity and unique selectivity. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Bimetallic alloy electrocatalysts with multilayered platinum-skin surfaces

    Science.gov (United States)

    Stamenkovic, Vojislav R.; Wang, Chao; Markovic, Nenad M.

    2016-01-26

    Compositions and methods of preparing a bimetallic alloy having enhanced electrocatalytic properties are provided. The composition comprises a PtNi substrate having a surface layer, a near-surface layer, and an inner layer, where the surface layer comprises a nickel-depleted composition, such that the surface layer comprises a platinum skin having at least one atomic layer of platinum.

  16. Journal of Chemical Sciences | Indian Academy of Sciences

    Indian Academy of Sciences (India)

    Home; Journals; Journal of Chemical Sciences; Volume 126; Issue 4. Synthesis and structural study of platinum group metal complexes containing pyrimidine bridged pyrazolyl-pyridine ligand and 5 and 6 - cyclic hydrocarbons. Thirumala Prasad Kota Mohan Rao Kollipara. Volume 126 Issue 4 July 2014 pp 1143-1151 ...

  17. Studies on the distribution of platinum in tumour-bearing rats after the administration of platinum co-ordination complexes used in cancer chemotherapy

    International Nuclear Information System (INIS)

    Zeisler, R.; Lux, F.; Beck, W.

    1979-01-01

    Platinum co-ordination complexes like dichlorodiamineplatinum(II) (DDP) feature broad spectrum antitumour activity which, however, is marred by a certain toxicity related especially to renal tubular damage. The activity of such drugs depends on the chemical structure of the complexes, with changes in the ligands resulting in changes in their antitumour activity and toxicity. Assessments of the biological and toxicological effects of recently synthesized complexes must include distribution studies of platinum in the body. It is demonstrated that instrumental neutron activation analysis can be used for these studies because of its accuracy, precision and the low detection limit for platinum (approximately equal to 2 ng), when a standardized method is used. The time-dependent retention of platinum was determined in blood, liver, kidneys and cells of ascitic Walker 256 carcinosarcoma in tumour-bearing rats and controls after the administration of the cis-Pt(Gly-Gly-0Et) 2 Cl 2 complex. Two series of experiments, one with the therapeutic amount of the drug (80 mg/kg body weight) and one low-dose experiment with 1/100 of this amount, were carried out. The results of both experiments are discussed with regard to changes in the platinum concentration with time (0-48 h) in the different samples. From the data a selective uptake of the drug by the tumour cells, causing their destruction, is deduced. Because this drug has shown excellent antitumour activity, this observed selectivity suggests promise for its application in cancer chemotherapy, although platinum retention is still found in the kidneys, which might cause renal tubular damage. This latter aspect requires further clinical research to evaluate fully its effects. (author)

  18. Structure-activity relationships of carbon-supported platinum-bismuth and platinum-antimony oxidation catalysts

    CSIR Research Space (South Africa)

    Maphoru, MV

    2017-04-01

    Full Text Available Compositional and morphological studies on supported platinum are important for the improvement and expanded use of catalysts for oxidative coupling reactions. Nanocomposites consisting of 5% Pt supported on activated carbon and promoted with 5% Bi...

  19. Preparation of Carbon-Platinum-Ceria and Carbon-Platinum-Cerium catalysts and its application in Polymer Electrolyte Fuel Cell: Hydrogen, Methanol, and Ethanol

    Science.gov (United States)

    Guzman Blas, Rolando Pedro

    This thesis is focused on fuel cells using hydrogen, methanol and ethanol as fuel. Also, in the method of preparation of catalytic material for the anode: Supercritical Fluid Deposition (SFD) and impregnation method using ethylenediaminetetraacetic acid (EDTA) as a chelating agent. The first part of the thesis describes the general knowledge about Hydrogen Polymer Exchange Membrane Fuel Cell (HPEMFC),Direct Methanol Fuel Cell (DMFC) and Direct Ethanol Fuel Cell (DEFC), as well as the properties of Cerium and CeO2 (Ceria). The second part of the thesis describes the preparation of catalytic material by Supercritical Fluid Deposition (SFD). SFD was utilized to deposit Pt and ceria simultaneously onto gas diffusion layers. The Pt-ceria catalyst deposited by SFD exhibited higher methanol oxidation activity compared to the platinum catalyst alone. The linear sweep traces of the cathode made for the methanol cross over study indicate that Pt-Ceria/C as the anode catalyst, due to its better activity for methanol, improves the fuel utilization, minimizing the methanol permeation from anode to cathode compartment. The third and fourth parts of the thesis describe the preparation of material catalytic material Carbon-Platinum-Cerium by a simple and cheap impregnation method using EDTA as a chelating agent to form a complex with cerium (III). This preparation method allows the mass production of the material catalysts without additional significant cost. Fuel cell polarization and power curves experiments showed that the Carbon-Platinum-Cerium anode materials exhibited better catalytic activity than the only Vulcan-Pt catalysts for DMFC, DEFC and HPEMFC. In the case of Vulcan-20%Pt-5%w Cerium, this material exhibits better catalytic activity than the Vulcan-20%Pt in DMFC. In the case of Vulcan-40% Pt-doped Cerium, this material exhibits better catalytic activity than the Vulcan-40% Pt in DMFC, DEFC and HPEMFC. Finally, I propose a theory that explains the reason why the

  20. Atomically flat platinum films grown on synthetic mica

    Science.gov (United States)

    Tanaka, Hiroyuki; Taniguchi, Masateru

    2018-04-01

    Atomically flat platinum thin films were heteroepitaxially grown on synthetic fluorophlogopite mica [KMg3(AlSi3O10)F2] by van der Waals epitaxy. Platinum films deposited on a fluorophlogopite mica substrate by inductively coupled plasma-assisted sputtering with oxygen introduction on a synthetic mica substrate resulted in the growth of twin single-crystalline epitaxial Pt(111) films.

  1. Bioaccumulation of platinum group metals in dolphins, Stenella sp ...

    African Journals Online (AJOL)

    Platinum group metals (PGMs) concentrations were measured in the tissues= of dolphins (Stenella sp.) caught along the Ghanaian coastline. Tissues from specimens caught by fishermen from Dixcove, western Ghana, were analysed in 2006 for palladium (Pd), platinum (Pt) and rhodium (Rh) using the Neutron Activation ...

  2. Pyrimidine dimer excision in human cells and skin cancer

    International Nuclear Information System (INIS)

    Regan, J.D.; Carrier, W.L.; Smith, D.P.; Waters, R.

    1977-01-01

    We have compared three different methods for estimating the induction and removal of uv induced pyrimidine dimers from the DNA of human fibroblasts. Results indicate that after uv doses of 5-20 J/m 2 50% of the dimers are removed by 24 hours after irradiation. Almost complete excision can be observed if the cells are incubated for periods not less than 72 hours after 5 J/m 2 . After higher doses it probably takes even longer fr such complete removal to be seen

  3. On the enzymatic formation of platinum nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Govender, Y.; Riddin, T. L. [Rhodes University, Department of Biochemistry, Microbiology and Biotechnology (South Africa); Gericke, M. [MINTEK (South Africa); Whiteley, C. G., E-mail: C.Whiteley@ru.ac.z [Rhodes University, Department of Biochemistry, Microbiology and Biotechnology (South Africa)

    2010-01-15

    A dimeric hydrogenase enzyme (44.5 and 39.4 kDa sub units) was isolated in a 39.5% yield from the fungus Fusarium oxysporum and purified 4.64-fold by ion exchange chromatography on Sephacryl S-200. Characterisation of the enzyme afforded pH and temperature optima of 7.5 and 38 {sup o}C, respectively, a half-life stability of 36 min and a V{sub max} and K{sub m} of 3.57 nmol min{sup -1} mL{sup -1} and 2.25 mM, respectively. This enzyme was inhibited (non-competitively) by hydrogen hexachloroplatinic acid (H{sub 2}PtCl{sub 6}) at 1 or 2 mM with a K{sub i} value of 118 {mu}M. Incubation of the platinum salt with the pure enzyme under an atmosphere of hydrogen and optimum enzyme conditions (pH 7.5, 38 {sup o}C) afforded <10% bioreduction after 8 h while at conditions suitable for platinum nanoparticle formation (pH 9, 65 {sup o}C) over 90% reduction took place after the same length of time. Cell-free extract from the fungal isolates produced nearly 90% bioreduction of the platinum salt under both pH and temperature conditions. The bioreduction of the platinum salt by a hydrogenase enzyme takes place by a passive process and not an active one as previously understood.

  4. Analgesic Activity of Some 1,2,4-Triazole Heterocycles Clubbed with Pyrazole, Tetrazole, Isoxazole and Pyrimidine

    Directory of Open Access Journals (Sweden)

    Ramdas Bhanudas Pandhare

    2013-02-01

    Full Text Available Purpose: In the present study in vivo analgesic activity of some previously synthesized 1,2,4-triazole derivatives containing pyrazole, tetrazole, isoxazole and pyrimidine ring have been evaluated. Methods: Acetic acid induced writhing method and Hot plate method has been described to study analgesic activity of some 1,2,4-triazole derivatives containing pyrazole, tetrazole, isoxazole and pyrimidine as a pharmacological active lead. Results: Thirty six different derivatives containing 1,2,4-triazole ring were subjected to study their in vivo analgesic activity. Chloro, nitro and methoxy, hydroxy and bromo substituted derivatives showed excellent analgesic activity and dimethylamino, furan and phenyl substituted derivatives showed moderate analgesic activity in both of the methods. Compounds IIIa, IIId, IIIf, IIIi, IIIj, IVa, IVb, IVd, IVf, IVh, IVj IV3a and IIj were found to be superior analgesic agents after screening by Acetic acid induced writhing method. Compounds IIIb, IIId, IIIf, IIIh, IIIj, IVa, IVb, IVd, IVf, IVh, IVi, IV3c, IV3e and IIj were showed analgesic potential after screening of Hot plate method. Conclusion: All tested compounds containing 1,2,4-triazole were found to be promising analgesic agents, for this activity pyrazole, tetrazole, isoxazole and pyrimidine leads might be supported.

  5. Recent strikes in South Africa’s platinum-group metal mines: effects upon world platinum-group metal supplies

    Science.gov (United States)

    Yager, Thomas R.; Soto-Viruet, Yadira; Barry, James J.

    2012-01-01

    The recent labor disputes over wages and working conditions that have affected South Africa’s three leading platinum-group metal (PGM) producers have affected an industry already plagued by market pressures and labor unrest and raised the specter of constraints in the world’s supply of these metals. Although low demand for these metals in 2011 and 2012 helped to offset production losses of recent years, and particularly those losses caused by the strikes in 2012, a prolonged resumption of strikes could cause severe shortages of iridium, platinum, rhodium, ruthenium, and, to a lesser extent, palladium.

  6. Investigation of a combined platinum and electron lifetime control treatment for silicon

    International Nuclear Information System (INIS)

    Jia, Yunpeng; Cui, Zhihang; Yang, Fei; Zhao, Bao; Zou, Shikai; Liang, Yongsheng

    2017-01-01

    In silicon, the effect of Combined Lifetime Treatment (CLT) involving platinum diffusion and subsequent electron irradiation is different from the separate treatments of platinum diffusion and electron irradiation, even the treatment of electron irradiation followed by platinum diffusion. In this paper, we investigated the experimental behavior of different kinds of lifetime treated samples. We found that the reverse leakage current (I rr ) increases with the increasing platinum diffusion temperature or electron irradiation dose in the separate treatments. Conversely, I rr of the CLT samples decreased with rising platinum diffusion temperature at the same dose of subsequent electron irradiation. By deep-level transient spectroscopy (DLTS), a new energy level E7 (Ec −0.376 eV) was found in our CLT samples. The new level E7 suppresses the dominance of the deeper level E8 (Ec −0.476 eV), which is caused by electron irradiation directly and results in I rr ’s increase. The formation of the level E7 comes from the complex defect-combined effect between platinum atoms and silicon vacancies, and it affects device’s characteristics finally. These research will be helpful to the development of platinum-diffused devices used in intense electron irradiation environments.

  7. Investigation of a combined platinum and electron lifetime control treatment for silicon

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Yunpeng [College of Electronic Information and Control Engineering, Beijing University of Technology, Beijing 100124 (China); Cui, Zhihang, E-mail: czhczh321321@126.com [College of Electronic Information and Control Engineering, Beijing University of Technology, Beijing 100124 (China); Yang, Fei [State Grid Smart Electrical Engineering, Beijing 100192 (China); Zhao, Bao; Zou, Shikai; Liang, Yongsheng [College of Electronic Information and Control Engineering, Beijing University of Technology, Beijing 100124 (China)

    2017-02-01

    In silicon, the effect of Combined Lifetime Treatment (CLT) involving platinum diffusion and subsequent electron irradiation is different from the separate treatments of platinum diffusion and electron irradiation, even the treatment of electron irradiation followed by platinum diffusion. In this paper, we investigated the experimental behavior of different kinds of lifetime treated samples. We found that the reverse leakage current (I{sub rr}) increases with the increasing platinum diffusion temperature or electron irradiation dose in the separate treatments. Conversely, I{sub rr} of the CLT samples decreased with rising platinum diffusion temperature at the same dose of subsequent electron irradiation. By deep-level transient spectroscopy (DLTS), a new energy level E7 (Ec −0.376 eV) was found in our CLT samples. The new level E7 suppresses the dominance of the deeper level E8 (Ec −0.476 eV), which is caused by electron irradiation directly and results in I{sub rr}’s increase. The formation of the level E7 comes from the complex defect-combined effect between platinum atoms and silicon vacancies, and it affects device’s characteristics finally. These research will be helpful to the development of platinum-diffused devices used in intense electron irradiation environments.

  8. Application of green chemistry techniques to prepare electrocatalysts for direct methanol fuel cells.

    Science.gov (United States)

    Shimizu, Kenichi; Wang, Joanna S; Wai, Chien M

    2010-03-25

    A series of green techniques for synthesizing carbon nanotube-supported platinum nanoparticles and their high electrocatalytic activity toward methanol fuel cell applications are reported. The techniques utilize either the supercritical fluid carbon dioxide or water as a medium for depositing platinum nanoparticles on surfaces of multiwalled or single-walled carbon nanotubes. The catalytic properties of the carbon nanotubes-supported Pt nanoparticle catalysts prepared by four different techniques are compared for anodic oxidation of methanol and cathodic reduction of oxygen using cyclic voltammetry. One technique using galvanic exchange of Pt(2+) in water with zerovalent iron present on the surfaces of as-grown single-walled carbon nanotubes produces a Pt catalyst that shows an unusually high catalytic activity for reduction of oxygen but a negligible activity for oxidation of methanol. This fuel-selective catalyst may have a unique application as a cathode catalyst in methanol fuel cells to alleviate the problems caused by crossover of methanol through the polymer electrolyte membrane.

  9. Mechanism for the abiotic synthesis of uracil via UV-induced oxidation of pyrimidine in pure H2O ices under astrophysical conditions

    International Nuclear Information System (INIS)

    Bera, Partha P.; Nuevo, Michel; Sandford, Scott A.; Lee, Timothy J.; Milam, Stefanie N.

    2010-01-01

    The UV photoirradiation of pyrimidine in pure H 2 O ices has been explored using second-order Moeller-Plesset perturbation theory and density functional theory methods, and compared with experimental results. Mechanisms studied include those starting with neutral pyrimidine or cationic pyrimidine radicals, and reacting with OH radical. The ab initio calculations reveal that the formation of some key species, including the nucleobase uracil, is energetically favored over others. The presence of one or several water molecules is necessary in order to abstract a proton which leads to the final products. Formation of many of the photoproducts in UV-irradiated H 2 O:pyrimidine=20:1 ice mixtures was established in a previous experimental study. Among all the products, uracil is predicted by quantum chemical calculations to be the most favored, and has been identified in experimental samples by two independent chromatography techniques. The results of the present study strongly support the scenario in which prebiotic molecules, such as the nucleobase uracil, can be formed under abiotic processes in astrophysically relevant environments, namely in condensed phase on the surface of icy, cold grains before being delivered to the telluric planets, like Earth.

  10. Platinum-Resistor Differential Temperature Sensor

    Science.gov (United States)

    Kolbly, R. B.; Britcliffe, M. J.

    1985-01-01

    Platinum resistance elements used in bridge circuit for measuring temperature difference between two flowing liquids. Temperature errors with circuit are less than 0.01 degrees C over range of 100 degrees C.

  11. Platinum catalyst formed on carbon nanotube by the in-liquid plasma method for fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Show, Yoshiyuki; Hirai, Akira; Almowarai, Anas; Ueno, Yutaro

    2015-12-01

    In-liquid plasma was generated in the carbon nanotube (CNT) dispersion fluid using platinum electrodes. The generated plasma spattered the surface of the platinum electrodes and dispersed platinum particles into the CNT dispersion. Therefore, the platinum nanoparticles were successfully formed on the CNT surface in the dispersion. The platinum nanoparticles were applied to the proton exchange membrane fuel cell (PEMFC) as a catalyst. The electrical power of 108 mW/cm{sup 2} was observed from the fuel cell which was assembled with the platinum catalyst formed on the CNT by the in-liquid plasma method. - Highlights: • The platinum catalyst was successfully formed on the CNT surface in the dispersion by the in-liquid plasma method. • The electrical power of 108 mW/cm{sup 2} was observed from the fuel cell which was assembled with the platinum catalyst formed on the CNT by the in-liquid plasma method.

  12. Efficient organic light-emitting devices with platinum-complex emissive layer

    KAUST Repository

    Yang, Xiaohui

    2011-01-18

    We report efficient organic light-emitting devices having a platinum-complex emissive layer with the peak external quantum efficiency of 17.5% and power efficiency of 45 lm W−1. Variation in the device performance with platinum-complex layer thickness can be attributed to the interplay between carrier recombination and intermolecular interactions in the layer. Efficient white devices using double platinum-complex layers show the external quantum efficiency of 10%, the Commission Internationale d’Énclairage coordinates of (0.42, 0.41), and color rendering index of 84 at 1000 cd m−2.

  13. Efficient organic light-emitting devices with platinum-complex emissive layer

    KAUST Repository

    Yang, Xiaohui; Wu, Fang-Iy; Haverinen, Hanna; Li, Jian; Cheng, Chien-Hong; Jabbour, Ghassan E.

    2011-01-01

    We report efficient organic light-emitting devices having a platinum-complex emissive layer with the peak external quantum efficiency of 17.5% and power efficiency of 45 lm W−1. Variation in the device performance with platinum-complex layer thickness can be attributed to the interplay between carrier recombination and intermolecular interactions in the layer. Efficient white devices using double platinum-complex layers show the external quantum efficiency of 10%, the Commission Internationale d’Énclairage coordinates of (0.42, 0.41), and color rendering index of 84 at 1000 cd m−2.

  14. Enzymatic recovery of platinum (IV) from industrial wastewater using ...

    African Journals Online (AJOL)

    highest hydrogen-dependent platinum (IV) reducing activity in the presence of hydrogenase and its physiological electron carrier, cytochrome c3. When the purified hydrogenase enzyme (with and without cytochrome c3) was used with the industrial effluent, containing 7.9 mg.l-1 platinum, only 10 – 15% recovery was noted ...

  15. Synthesis and antitumor activity of some novel thiophene, pyrimidine, coumarin, pyrazole and pyridine derivatives

    Directory of Open Access Journals (Sweden)

    Albratty Mohammed

    2017-03-01

    Full Text Available 2-Cyano-N-(thiazol-2-yl acetamide (2a and 2-cyano-N-(oxazol- 2-yl acetamide (2b were obtained via the reaction of ethyl cyanoacetate with either 2-aminothiazole (1a or 2-aminooxazole (1b. The formed products were directed toward the reaction with cyclopentanone and elemental sulfur in the presence of triethylamine to give cyclopenta[b]thiophene derivatives (3a,b. The latter products were reacted with either ethyl cyanoacetate or malononitrile to form compounds 4a,b and 5a,b, respectively. Compounds 4a,b were aimed at synthesizing some heterocyclic compounds; thus internal cyclization reactions were introduced to form compounds 6a,b. Also, compounds 4a,b reacted with salicylaldehyde, hydrazine derivatives and either urea or thiourea to produce coumarin derivatives (7a,b, pyrazole derivatives (8a-d and pyrimidine derivatives (9a-d, respectively. Reaction of either benzaldehyde or benzene diazonium chloride (11 with compounds 4a,b afforded compounds 10a,b and 12a,b, respectively. On the other hand, compounds 5a,b underwent internal cyclization to form pyrimidine derivatives 13a,b. Also, when compounds 5a,b reacted with either ethyl cyanoacetate or malononitrile, they gave pyridine derivatives (15a-d through the formation of intermediates (14a-d. Finally, formation of fused pyrimidine derivatives (17a,b was achieved through the reaction of compounds 5a,b and salicylaldehyde applying two different pathways. The first pathway used a catalytic amount of piperidine to form compounds 16a,b; the latter products underwent cyclization to give compounds 17a,b. The second pathway, using a catalytic amount of sodium ethoxide solution directly in one step, afforded compounds 17a,b. Structures of the newly synthesized compounds were established using IR, 1H NMR, 13C NMR and mass spectrometry and their antitumor activity was investigated. Some of these compounds showed promising inhibitory effects on three different cell lines. However, fused pyrimidine

  16. Growth of uniform nanoparticles of platinum by an economical approach at relatively low temperature

    KAUST Repository

    Shah, M.A.

    2012-01-01

    Current chemical methods of synthesis have shown limited success in the fabrication of nanomaterials, which involves environmentally malignant chemicals. Environmental friendly synthesis requires alternative solvents, and it is expected that the use of soft options of green approaches may overcome these obstacles. Water, which is regarded as a benign solvent, has been used in the present work for the preparation of platinum nanoparticles. The average particle diameter is in the range of ∼13±5 nm and particles are largely agglomerated. The advantages of preparing nanoparticles with this method include ease, flexibility and cost effectiveness. The prospects of the process are bright, and the technique could be extended to prepare many other important metal and metal oxide nanostructures. © 2012 Sharif University of Technology. Production and hosting by Elsevier B.V. All rights reserved.

  17. Growth of uniform nanoparticles of platinum by an economical approach at relatively low temperature

    KAUST Repository

    Shah, M.A.

    2012-06-01

    Current chemical methods of synthesis have shown limited success in the fabrication of nanomaterials, which involves environmentally malignant chemicals. Environmental friendly synthesis requires alternative solvents, and it is expected that the use of soft options of green approaches may overcome these obstacles. Water, which is regarded as a benign solvent, has been used in the present work for the preparation of platinum nanoparticles. The average particle diameter is in the range of ∼13±5 nm and particles are largely agglomerated. The advantages of preparing nanoparticles with this method include ease, flexibility and cost effectiveness. The prospects of the process are bright, and the technique could be extended to prepare many other important metal and metal oxide nanostructures. © 2012 Sharif University of Technology. Production and hosting by Elsevier B.V. All rights reserved.

  18. Honey Mediated Green Synthesis of Nanoparticles: New Era of Safe Nanotechnology

    Directory of Open Access Journals (Sweden)

    Eranga Roshan Balasooriya

    2017-01-01

    Full Text Available With the advent of nanotechnology, many related industries rapidly developed over the recent past. Generally, top-down and bottom-up approaches are the two major processes used to synthesize nanoparticles; most of these require high temperatures, vacuum conditions, and harsh/toxic chemicals. As a consequence, adverse effects impacted organisms including humans. Some synthesis methods are expensive and time-consuming. As a corollary, the concept of “green nanotechnology” emerged with the green synthesis of nanoparticles commencing a new epoch in nanotechnology. This involves the synthesis of nanomaterial from microorganisms, macroorganisms, and other biological materials. Honey is documented as the world’s oldest food source with exceptional medical, chemical, physical, and pharmaceutical values. Honey mediated green synthesis is a relatively novel concept used during the past few years to synthesize gold, silver, carbon, platinum, and palladium nanoparticles. Honey acts as both a stabilizing and a reducing agent and importantly functions as a precursor in nanoparticle synthesis. This method usually requires room temperature and does not produce toxic byproducts. In conclusion, honey mediated green synthesis of nanoparticles provides a simple, cost effective, biocompatible, reproducible, rapid, and safe method. The special activity of honey functionalized nanoparticles may provide valuable end products with numerous applications in diverse fields.

  19. Pyrimidine dimer formation and repair in human skin

    International Nuclear Information System (INIS)

    Sutherland, B.M.; Harber, L.C.; Kochevar, I.E.

    1980-01-01

    Cyclobutyl pyrimidine dimers have been detected in the DNA of human skin following in vivo irradiation with suberythermal doses of ultraviolet (UV) radiation from FS-20 sun lamp fluorescent tubes. Dimers were assayed by treatment of extracted DNA with Micrococus luteus UV-specific endonuclease, alkaline agarose electrophoresis, and ethidum bromide staining. This technique, in contrast to conventional dimer assays, can be used with nonradioactive DNA and is optimal at low UV light doses. These data suggest that some dimer disappearance by excision repair occurs within 20 min of UV irradiation and that photoreactivation of dimers can make a contribution to the total repair process

  20. Structural property of platinum mononitride

    International Nuclear Information System (INIS)

    Yu, L.H.; Yao, K.L.; Liu, Z.L.; Zhang, Y.S.

    2007-01-01

    The structural stability and pressure-induced structural phase transition of platinum mononitride (PtN), as well as its electronic structure, were studied using the full potential augmented plane wave plus local orbitals method with the generalized gradient approximation (GGA) exchange-correlation functional. The total energy calculations show that the optimized wurtzite structure is most stable energetically among four structures: zinc blende, rocksalt, CsCl and wurtzite, which reveals the platinum mononitride PtN perhaps crystallizes in the wurtzite structure; the pressure of phase transition from wurtzite to rocksalt is predicted to be 41.4 GPa.The calculated bulk modulus of the wurtzite structure is 99.41 GPa, which is smaller than that of the other three structures and face-centered cubic Pt. The band structure calculations show wurtzite PtN is metallic

  1. Microwave assisted one-pot catalyst free green synthesis of new methyl-7-amino-4-oxo-5-phenyl-2-thioxo-2,3,4,5-tetrahydro-1H-pyrano[2,3-d]pyrimidine-6-carboxylates as potent in vitro antibacterial and antifungal activity

    Directory of Open Access Journals (Sweden)

    Ajmal R. Bhat

    2015-11-01

    Full Text Available An efficiently simple protocol for the synthesis of methyl 7 amino-4-oxo-5-phenyl-2-thioxo-2, 3, 4,5-tetrahydro-1H-pyrano[2,3-d]pyrimidine-6-carboxylates via one-pot three component condensation pathway is established via microwave irradiation using varied benzaldehyde derivatives, methylcyanoacetate and thio-barbituric acid in water as a green solvent. A variety of functionalized substrates were found to react under this methodology due to its easy operability and offers several advantages like, high yields (78–94%, short reaction time (3–6 min, safety and environment friendly without used any catalyst. The synthesized compounds (4a–4k showed comparatively good in vitro antimicrobial and antifungal activities against different strains. The Compounds 4a, 4b, 4c, 4d 4e and 4f showed maximum antimicrobial activity against Staphylococcus aureus, Bacillus cereus (gram-positive bacteria, Escherichia coli, Klebshiella pneumonia, Pseudomonas aeruginosa (gram-negative bacteria. The synthesized compound 4f showed maximum antifungal activity against Aspergillus Niger and Penicillium chrysogenum strains. Streptomycin is used as standard for bacterial studies and Mycostatin as standards for fungal studies. Structure of all newly synthesized products was characterized on the basis of IR, 1H NMR, 13C NMR and mass spectral analysis.

  2. Tripodal osmium polypyridyl complexes for self-assembly on platinum nanoparticles

    NARCIS (Netherlands)

    Contreras-Carballada, P.; Edafe, F.; Tichelaar, F.D.; Belser, P.; De Cola, L.; Williams, R.M.

    2011-01-01

    The combination of platinum nanoparticles with a tripodal osmium complex that anchors to the metal surface leads, under visible light irradiation, to the formation of solvated electrons. The formation kinetics is limited by the detachment of the electron from the platinum surface into the solution,

  3. Synthesis, cyclooxygenase inhibition, anti-inflammatory evaluation and ulcerogenic liability of new 1-phenylpyrazolo[3,4-d]pyrimidine derivatives.

    Science.gov (United States)

    Bakr, Rania B; Azouz, Amany A; Abdellatif, Khaled R A

    2016-01-01

    A new group of 1-phenylpyrazolo[3,4-d]pyrimidine derivatives 14a-d-21 were synthesized from 2-(6-methyl-1-phenyl-1H-pyrazolo[3,4-d]pyrimidin-4-yloxy)acetohydrazide (12). All the synthesized compounds were evaluated for their cyclooxygenase (COX) inhibition, anti-inflammatory activity and ulcerogenic liability. All the target compounds were more potential in inhibiting COX-2 than COX-1. Compounds having pyrazolyl moiety in a hybrid structure with pyrazolo[3,4-d]pyrimidine scaffold (14a-d, 16 and 17) showed higher edema inhibition percentage activities (34-68%) and the 5-aminopyrazole derivative (14c, ED 50  =   87.9 μmol/kg) was the most potent one > celecoxib (ED 50  =   91.9 μmol/kg). While, the in vivo potent compounds (14a-d, 16, 17 and 21) caused variable ulceration effect (ulcer index   = 0.33-4.0) comparable to that of celecoxib (ulcer index   = 0.33), the pyrazol-3-one derivative (16) and the acetohydrazide (21) were the least ulcerogenic derivatives showing the same ulcerogenic potential of celecoxib.

  4. In vitro anti-Giardia lamblia activity of 2-aryl-3-hydroxymethyl imidazo[1,2-a]pyridines and -pyrimidines, individually and in combination with albendazole.

    Science.gov (United States)

    Velázquez-Olvera, Stephanía; Salgado-Zamora, Héctor; Jiménez-Cardoso, Enedina; Campos-Aldrete, Maria-Elena; Pérez-González, Cuauhtémoc; Ben Hadda, Taibi

    2016-03-01

    Giardiasis is a major diarrheal disease found throughout the world, the causative agent being the flagellate protozoan Giardia intestinalis. Infection is more common in children than in adults. The appearance of drug resistance has complicated the treatment of several parasitic diseases, including giardiasis. Thus, the aim of this investigation was to make an in vitro evaluation of the antigiardia response of synthetic derivatives 2-aryl-3-hydroxymethylimidazo[1,2-a]pyridines 1 and -pyrimidines 2 against trophozoites of Giardia lamblia WB, in comparison with the reference drug, albendazole. Additionally, the synergistic action of albendazole in combination with each of the most active 2-aryl-3-hydroxymethyl imidazo[1,2-a]pyridines and pyrimidines was also assessed. Based on the IC50 values obtained, the best anti-Giardia activity was provided by the 3-hydroxymethyl-4-fluorophenylimidazo[1,2-a]pyrimidine derivative 2c and the corresponding imidazo[1,2-a]pyrimidine with the p-tolyl substituent 2d, followed by 2a and 2b. These four compounds showed effectiveness at a concentration similar to that of albendazole. Regarding synergism, the IC50 of the combination of albendazole with 2a, 2b or 2c gave the best anti-Giardia action, showing greater efficacy than albendazole alone. Hence, G. lamblia WB showed high susceptibility to some 2-aryl-3-hydroxymethyl imidazo[1,2-a] pyrimidines, which acted synergistically when used in combination with albendazole. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Enhanced repair of cyclobutane pyrimidine dimers and improved UV resistance in photolyase transgenic mice

    NARCIS (Netherlands)

    W. Schul; J. Jans (Judith); Y.M. Rijksen (Yvonne); K.H. Klemann; J. de Wit (Jan); O. Nikaido; S. Nakajima; A. Yasui (Akira); J.H.J. Hoeijmakers (Jan); G.T.J. van der Horst (Gijsbertus); A.P.M. Eker (André)

    2002-01-01

    textabstractDuring evolution, placental mammals appear to have lost cyclobutane pyrimidine dimer (CPD) photolyase, an enzyme that efficiently removes UV-induced CPDs from DNA in a light-dependent manner. As a consequence, they have to rely solely on the more complex, and for this lesion less

  6. Platinum single crystal electrodes for the electrocatalysis of methane oxidation

    Directory of Open Access Journals (Sweden)

    Mayara Munaretto

    2011-03-01

    Full Text Available The main objective of this paper is to characterize the voltammetric profiles of platinum single crystals of low Miller indexes Pt(100 and Pt(110 and study their catalytic activities on the oxidation of methane. In this way, it was developed a metallic surface modified by presence of other metal oxide, which presents catalytic activity for this reaction. It is well known that the electrooxidation of methane (CH4 leads mainly to the formation of CO2 and H2O, however, the oxidation can also lead to the formation of CO, a reaction intermediate that has strong interaction with metal surfaces, such as platinum. This molecule tends to accumulate on the platinum surface and to passive it, due to the self-poisoning, decreasing its catalytic activity. Therefore, the main aim of this work was the development of a platinum electrode modified by deposition of titanium oxide, which presented electrocatalytic properties for the oxidation of methane.

  7. Facile synthesis of indole-pyrimidine hybrids and evaluation of their anticancer and antimicrobial activity

    Directory of Open Access Journals (Sweden)

    Nikhila Gokhale

    2017-11-01

    Full Text Available The paper describes the facile synthesis of new N-cyclopropyl-1-methyl-1H-indole-2-carboxamide derivatives bearing substituted 2-amino pyrimidine moiety at position-3 of the indole ring. All the intermediate and title compounds were characterized adeptly by 1H NMR, 13C NMR, ESI–MS and elemental analyses. These compounds were evaluated for their in vitro anticancer activity against HeLa, HepG2 and MCF-7 cells. Three among 22 molecules, showed more than 70% growth inhibition against all three tested cancer cells. The nature of the substituent group on the pyrimidine ring (R2 affected significantly the anti-proliferative activity of the molecules. The anti-microbial evaluation of the title molecules revealed the significance of fluoro/chloro groups (R2 in enhancing their inhibition activity. Eight molecules which contain fluoro/chloro groups showed potent anti-microbial activity. In addition, the active molecules displayed negligible toxicity to benign Vero cells.

  8. Concentration and measuring Platinum Group Elements (PGE) Transfer Factor in soil and vegetations

    International Nuclear Information System (INIS)

    Adibah Sakinah Oyub

    2012-01-01

    This study was conducted to determine the concentration and to measure platinum group elements (PGE) transfer factor in environmental samples of roadside soil and vegetation. The use of vehicle catalytic converter has released platinum group elements (PGE) and other gases into the environment. Thus, roadside soil and plants were exposed to this element and has become the medium for the movement of this elements. Samples of roadside soil and vegetation were taken at various locations in UKM Bangi Toll and the concentration of platinum group elements (PGE) is determined using mass spectrometry-inductively coupled plasma (ICP-MS). Overall, the concentrations of platinum group elements (PGE), which is the element platinum (Pt) in soil was 0.016 ± 0.036 μgg -1 . While the concentration of the elements palladium (Pd) was 0.079 ± 0.019 μgg -1 and element rhodium (Rh) is at a concentration of 0.013 ± 0.020 μgg -1 . Overall, the transfer factor for the element platinum (Pt) is 1. While the transfer factor of the element palladium (Pd) is 0.96 and the element rhodium (Rh) is 1.11. In conclusion, the concentration of platinum group elements (PGE) in soils have increased. (author)

  9. LDRD final report on synthesis of shape-and size-controlled platinum and platinum alloy nanostructures on carbon with improved durability.

    Energy Technology Data Exchange (ETDEWEB)

    Shelnutt, John Allen; Garcia, Robert M.; Song, Yujiang; Moreno, Andres M.; Stanis, Ronald J.

    2008-10-01

    This project is aimed to gain added durability by supporting ripening-resistant dendritic platinum and/or platinum-based alloy nanostructures on carbon. We have developed a new synthetic approach suitable for directly supporting dendritic nanostructures on VXC-72 carbon black (CB), single-walled carbon nanotubes (SWCNTs), and multi-walled carbon nanotubes (MWCNTs). The key of the synthesis is to creating a unique supporting/confining reaction environment by incorporating carbon within lipid bilayer relying on a hydrophobic-hydrophobic interaction. In order to realize size uniformity control over the supported dendritic nanostructures, a fast photocatalytic seeding method based on tin(IV) porphyrins (SnP) developed at Sandia was applied to the synthesis by using SnP-containing liposomes under tungsten light irradiation. For concept approval, one created dendritic platinum nanostructure supported on CB was fabricated into membrane electrode assemblies (MEAs) for durability examination via potential cycling. It appears that carbon supporting is essentially beneficial to an enhanced durability according to our preliminary results.

  10. Platinum-Bismuth Bimetallic Catalysts: Synthesis, Characterization and Applications

    OpenAIRE

    Saucedo, Jose A, Jr; Xiao, Yang; Varma, Arvind

    2015-01-01

    Bimetallic catalysts have been explored and shown to exhibit unique characteristics which are not present in monometallic catalysts. Platinum is well known as an effective catalyst for oxidation and reduction reactions, and it can be made more effective when bismuth is introduced as a promotor. Thus, the effectiveness of the Pt-Bi catalyst was demonstrated in prior work. What is not clear, however, is the mechanism behind the catalyst function; why addition of bismuth to platinum decreases de...

  11. Uridine 5'-Monophosphate Synthase Is Transcriptionally Regulated by Pyrimidine Levels in Nicotiana plumbaginifolia

    Science.gov (United States)

    Santoso; Thornburg

    1998-02-01

    To understand the regulation and expression of pyrimidine biosynthesis in plants, we have examined the effect of the metabolic inhibitor 5-fluoroorotic acid (FOA) on uridine-5'-monophosphate synthase (UMPSase) expression in cell cultures of Nicotiana plumbaginifolia. UMPSase is the rate-limiting step of pyrimidine biosynthesis in plants. Addition of FOA causes an up-regulation of UMPSase enzyme activity in cell cultures after a lag phase of several days. Western-blot analysis demonstrated that the up-regulation in enzyme activity was caused by increased expression of the UMPSase protein. Northern-blot analysis demonstrated a higher level of UMPSase mRNA in the FOA-induced tissues than in control tissues. Run-on transcriptional assays showed that the UMPSase gene was transcriptionally activated after FOA treatment. The mechanism of toxicity of FOA is through thymine starvation. We found that addition of thymine abrogated the FOA-mediated up-regulation of UMPSase. In addition, methotrexate and aminopterin, which affect thymine levels by inhibiting dihydrofolate reductase, also up-regulate UMPSase in N. plumbaginifolia cells.

  12. Cytotoxic evaluation upon cis-platinum aminodiacetic acid complexes

    International Nuclear Information System (INIS)

    Almah binti Awaluddin; Parsons, Peter G.; Lean, Jenny M.; Jacobs, Jeffrey J.

    1990-01-01

    Cytoxic study of cis-platinum aminodiacetic acid complexes. Three novel platinum complexes have been synthesised and characterised by Awaluddin et. al (1987). This introduces a new area of radiopharmaceuticals based on technician and platinum. Cytotoxic studies were conducted on these complexes using four different types of cell lines. The para amina was found to be highly active against multi-resistant ovarian tumor cells compared to normal cells (fibroblast) and other tumor cells. The chemical structure of para-amina appears to be devoid of any functional group resembling current antitumor drugs except for a distant similarity to metotrexate with respect to the p-aminobenzoic type structure. However cell lines such as Hela and MM 253c-1, which is sensitive to metotrexate, were not sensitive to the para amina. Preliminary studies have shown that cells are blocked in the G phase of the cell cycle, suggesting an antimetabolite effect

  13. Pyrimidine and nucleoside gamma-esters of L-Glu-Sar

    DEFF Research Database (Denmark)

    Eriksson, André H; Elm, Peter L; Begtrup, Mikael

    2005-01-01

    -tetrahydrofuran-3-yl ester)-Sar (I), l-Glu(thymine-1-yl-methyl ester)-Sar (II) and l-Glu(acyclothymidine)-Sar (III) were synthesised and in vitro stability was studied in various aqueous and biological media. Affinity to and translocation via hPEPT1 was investigated in mature Caco-2 cell monolayers, grown......The aim of the present study was to improve the synthetic pathway of bioreversible dipeptide derivatives as well as evaluate the potential of using l-Glu-Sar as a pro-moiety for delivering three newly synthesised nucleoside and pyrimidine l-Glu-Sar derivatives. l-Glu(trans-2-thymine-1-yl...

  14. Microstructural Study on Oxidation Resistance of Nonmodified and Platinum Modified Aluminide Coating

    Science.gov (United States)

    Zagula-Yavorska, Maryana; Sieniawski, Jan

    2014-03-01

    Platinum electroplating layers (3 and 7 μm thick) were deposited on the surface of the Inconel 713 LC, CMSX 4, and Inconel 625 Ni-base superalloys. Diffusion treatment at 1050°C for 2 h under argon atmosphere was performed after electroplating. Diffusion treated samples were aluminized according to the low activity CVD process at 1050°C for 8 h. The nonmodified aluminide coatings consist of NiAl phase. Platinum modification let to obtain the (Ni,Pt)Al phase in coatings. The coated samples were subjected to cyclic oxidation testing at 1100°C. It was discovered that increase of the platinum electroplating thickness from 3 to 7 μm provides the improvement of oxidation resistance of aluminide coatings. Increase of the platinum thickness causes decreases in weight change and decreases in parabolic constant during oxidation. The platinum provides the pure Al2O3 oxide formation, slow growth oxide layer, and delay the oxide spalling during heating-cooling thermal cycles.

  15. Formation of pyrimidine dimers in Simian virus 40 chromosomes and DNA in vitro: effects of salt

    International Nuclear Information System (INIS)

    Edenberg, H.J.

    1984-01-01

    Simian virus 40 chromosomes were used to determine whether packaging of DNA into chromatin affected the yield of cylcobutane pyrimidine dimers introduced by ultraviolet light (254 nm). SV40 chromatin and purified SV40 DNA (radioactively labeled with different isotopes) were mixed and irradiated in vitro. The proteins were extracted and pyrimidine dimers detected as sites sensitive to the UV-endonuclease encoded by bacteriophage T4. When irradiation was carried out in the presence of at least 0.05 M NaCl the same number of dimers were formed in chromatin as in free DNA. Irradiation in the absence of NaCl, however, reduced the relative yield of dimers in chromatin to 89% of that in free DNA. Different methods of chromatin preparation did not influence these results. (author)

  16. VUV Study of Electron-Pyrimidine Dissociative Excitation

    Science.gov (United States)

    Hein, Jeff; Al-Khazraji, Hajar; Tiessen, Collin; Lukic, Dragan; Trocchi, Joshuah; McConkey, William

    2013-05-01

    A crossed electron-gas beam system coupled to a VUV spectrometer has been used to investigate the dissociation of pyrimidine (C4H4N2) into excited atomic fragments in the electron-impact energy range from threshold to 375 eV. Data have been made absolute using Lyman- α from H2 as a secondary standard. The main features in the spectrum are the H Lyman series lines. The emission cross section of Lyman- α is measured to be (2.44 +/- 0.25) 10-18 cm2 at 100 eV impact energy. The probability of extracting C or N atoms from the ring is shown to be very small. Possible dissociation channels and excitation mechanisms in the parent molecule will be discussed. The authors thank NSERC (Canada) for financial support.

  17. Harman inhibits the removal of pyrimidine dimers from the DNA of human cells

    International Nuclear Information System (INIS)

    Castellani, A.; Setlow, R.B.

    1981-01-01

    Normal human fibroblasts were UV-irradiated and incubated for 6 hr with harman. The losses of sites, in the extracted DNA, sensitive to a UV specific endonuclease were determined as precision measures of the excision of UV-induced pyrimidine dimers. Harman inhibited excision, rising from approx. 30% inhibition at 200 μM to 75% inhibition at 500 μM

  18. Replication of UV-irradiated single-stranded DNA by DNA polymerase III holoenzyme of Escherichia coli: evidence for bypass of pyrimidine photodimers

    International Nuclear Information System (INIS)

    Livneh, Z.

    1986-01-01

    Replication of UV-irradiated circular single-stranded phage M13 DNA by Escherichia coli RNA polymerase (EC 2.7.7.6) and DNA polymerase III holoenzyme (EC 2.7.7.7) in the presence of single-stranded DNA binding protein yielded full-length as well as partially replicated products. A similar result was obtained with phage G4 DNA primed with E. coli DNA primase, and phage phi X174 DNA primed with a synthetic oligonucleotide. The fraction of full-length DNA was several orders of magnitude higher than predicted if pyrimidine photodimers were to constitute absolute blocks to DNA replication. Recent models have suggested that pyrimidine photodimers are absolute blocks to DNA replication and that SOS-induced proteins are required to allow their bypass. Our results demonstrate that, under in vitro replication conditions, E. coli DNA polymerase III holoenzyme can insert nucleotides opposite pyrimidine dimers to a significant extent, even in the absence of SOS-induced proteins

  19. Niraparib Maintenance Therapy in Platinum-Sensitive, Recurrent Ovarian Cancer

    DEFF Research Database (Denmark)

    Mirza, Mansoor R; Monk, Bradley J; Herrstedt, Jørn

    2016-01-01

    Background Niraparib is an oral poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) 1/2 inhibitor that has shown clinical activity in patients with ovarian cancer. We sought to evaluate the efficacy of niraparib versus placebo as maintenance treatment for patients with platinum-sensitive, ......Background Niraparib is an oral poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) 1/2 inhibitor that has shown clinical activity in patients with ovarian cancer. We sought to evaluate the efficacy of niraparib versus placebo as maintenance treatment for patients with platinum...... or 4 adverse events that were reported in the niraparib group were thrombocytopenia (in 33.8%), anemia (in 25.3%), and neutropenia (in 19.6%), which were managed with dose modifications. Conclusions Among patients with platinum-sensitive, recurrent ovarian cancer, the median duration of progression...

  20. Combined chemotherapy including platinum derivatives for medulloblastoma. The usefulness as maintenance chemotherapy

    International Nuclear Information System (INIS)

    Sasaki, Hikaru; Otani, Mitsuhiro; Yoshida, Kazunari; Kagami, Hiroshi; Shimazaki, Kenji; Toya, Shigeo; Kawase, Takeshi

    1997-01-01

    The authors reviewed 24 cerebellar medulloblastoma patients treated at Keio University to determine usefulness of combined chemotherapy including platinum derivatives (cisplatin, carboplatin) as the induction and maintenance treatment. All patients underwent radical surgery and craniospinal irradiation. Ten received adjuvant chemotherapy other than platinum derivatives (mainly with nitrosourea compounds), five were treated by induction and maintenance chemotherapy including platinum derivatives, and nine patients did not undergo chemotherapy. The progression-free survival rate of patients treated with platinum derivatives was better than that of patients treated with other modes of chemotherapy and also that of patients who did not receive chemotherapy. The results were especially good in the case of four patients treated with maintenance chemotherapy consisting of carboplatin and etoposide, two of whom had been free from relapse beyond the risk period of Collins. The occurrences of toxicity in maintenance chemotherapy with carboplatin and etoposide were limited to transient leucopenia. The present study indicates combined chemotherapy including platinum derivatives benefits patients with medulloblastoma, and could be useful, especially as maintenance treatment. (author)

  1. Towards green loyalty: the influences of green perceived risk, green image, green trust and green satisfaction

    Science.gov (United States)

    Chrisjatmiko, K.

    2018-01-01

    The paper aims to present a comprehensive framework for the influences of green perceived risk, green image, green trust and green satisfaction to green loyalty. The paper also seeks to account explicitly for the differences in green perceived risk, green image, green trust, green satisfaction and green loyalty found among green products customers. Data were obtained from 155 green products customers. Structural equation modeling was used in order to test the proposed hypotheses. The findings show that green image, green trust and green satisfaction has positive effects to green loyalty. But green perceived risk has negative effects to green image, green trust and green satisfaction. However, green perceived risk, green image, green trust and green satisfaction also seems to be a good device to gain green products customers from competitors. The contributions of the paper are, firstly, a more complete framework of the influences of green perceived risk, green image, green trust and green satisfaction to green loyalty analyses simultaneously. Secondly, the study allows a direct comparison of the difference in green perceived risk, green image, green trust, green satisfaction and green loyalty between green products customers.

  2. Cellular distribution, purification and electrophoretic properties of malate dehydrogenase in Trichuris ovis and inhibition by benzimidazoles and pyrimidine derivatives.

    Science.gov (United States)

    Sanchez-Moreno, M; Ortega, J E; Valero, A

    1989-12-01

    High levels of malate dehydrogenase were found in Trichuris ovis. Two molecular forms of the enzyme, of different cellular location and electrophoretic pattern, were isolated and purified. The activity of soluble malate dehydrogenase was greater than that of mitochondrial malate dehydrogenase. Both forms also displayed different electrophoretic profiles in comparison with purified extracts from goat (Capra hircus) liver. Substrate concentration directly affected enzyme activity. Host and parasite malate dehydrogenase activity were both inhibited by a series of benzimidazoles and pyrimidine-derived compounds, some of which markedly reduced parasite enzyme activity, but not host enzyme activity. Percentage inhibition by some pyrimidine derivatives was greater than that produced by benzimidazoles.

  3. A General Regioselective Approach to 2,4-Disubstituted Pyrimidin-5-yl C-2-Deoxyribonucleosides

    Czech Academy of Sciences Publication Activity Database

    Kubelka, Tomáš; Slavětínská, Lenka; Hocek, Michal

    2012-01-01

    Roč. 44, č. 6 (2012), s. 953-965 ISSN 0039-7881 R&D Projects: GA MŠk LC512; GA AV ČR IAA400550902 Institutional research plan: CEZ:AV0Z40550506 Keywords : nucleosides * pyrimidines * cross - coupling * Heck reaction Subject RIV: CC - Organic Chemistry Impact factor: 2.500, year: 2012

  4. Rapid and Efficient Collection of Platinum from Karstedt's Catalyst Solution via Ligands-Exchange-Induced Assembly.

    Science.gov (United States)

    Yang, Gonghua; Wei, Yanlong; Huang, Zhenzhu; Hu, Jiwen; Liu, Guojun; Ou, Ming; Lin, Shudong; Tu, Yuanyuan

    2018-02-21

    Reported herein is a novel strategy for the rapid and efficient collection of platinum from Karstedt's catalyst solution. By taking advantage of a ligand-exchange reaction between alkynols and the 1,3-divinyltetramethyldisiloxane ligand (M Vi M Vi ) that coordinated with platinum (Pt(0)), the Karstedt's catalyst particles with a size of approximately 2.5 ± 0.7 nm could be reconstructed and assembled into larger particles with a size of 150 ± 35 nm due to the hydrogen bonding between the hydroxyl groups of the alkynol. In addition, because the silicone-soluble M Vi M Vi ligand of the Karstedt's catalyst was replaced by water-soluble alkynol ligands, the resultant large particles were readily dispersed in water, resulting in rapid, efficient, and complete collection of platinum from the Karstedt's catalyst solutions with platinum concentrations in the range from ∼20 000 to 0.05 ppm. Our current strategy not only was used for the rapid and efficient collection of platinum from the Karstedt's catalyst solutions, but it also enabled the precise evaluation of the platinum content in the Karstedt's catalysts, even if this platinum content was extremely low (i.e., 0.05 ppm). Moreover, these platinum specimens that were efficiently collected from the Karstedt's catalyst solutions could be directly used for the evaluation of platinum without the need for pretreatment processes, such as calcination and digestion with hydrofluoric acid, that were traditionally used prior to testing via inductively coupled plasma mass spectrometry in conventional methods.

  5. Structure of matrix metalloproteinase-3 with a platinum-based inhibitor.

    Science.gov (United States)

    Belviso, Benny Danilo; Caliandro, Rocco; Siliqi, Dritan; Calderone, Vito; Arnesano, Fabio; Natile, Giovanni

    2013-06-18

    An X-ray investigation has been performed with the aim of characterizing the binding sites of a platinum-based inhibitor (K[PtCl3(DMSO)]) of matrix metalloproteinase-3 (stromelysin-1). The platinum complex targets His224 in the S1' specificity loop, representing the first step in the selective inhibition process (PDB ID code 4JA1).

  6. Same-Side Platinum Electrodes for Metal Assisted Etching of Porous Silicon

    Science.gov (United States)

    2015-11-01

    Platinum Electrodes for Metal Assisted Etching of Porous Silicon by Matthew H Ervin and Brian Isaacson Sensors and Electron Devices Directorate...SUBTITLE Same-Side Platinum Electrodes for Metal Assisted Etching of Porous Silicon 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT

  7. An efficient synthesis of novel pyrano[2,3-d]- and furopyrano[2,3-d]pyrimidines via indium-catalyzed multi-component domino reaction

    Directory of Open Access Journals (Sweden)

    Gohain Mukut

    2006-06-01

    Full Text Available Abstract Various novel pyrano [2,3-d]pyrimidines 5 and furopyrano [2,3-d]pyrimidines 7 were synthesized in 80–99% yields via a multicomponent domino Knoevenagel/hetero-Diels-Alder reaction of 1,3-dimethyl barbituric acid with an aromatic aldehyde and ethyl vinyl ether/2,3-dihydrofuran in presence of 1 mol% of indium(III chloride. The reaction also proceeds in aqueous media without using any catalyst, but the yield is comparatively less (65–70%.

  8. Optimising the treatment of the partially platinum-sensitive relapsed ovarian cancer patient

    Directory of Open Access Journals (Sweden)

    Nicoletta Colombo

    2014-12-01

    Full Text Available The choice of second-line chemotherapy in patients with recurrent ovarian cancer (ROC is complex, with several factors to be considered, the most important of which is the length of the platinum-free treatment interval (PFI. Recently ROC patients have been further stratified into platinum sensitive (PS, partially platinum sensitive (PPS and platinum resistant (PR subgroups depending on the length of the PFI. Response to second-line therapy, progression-free survival (PFS and overall survival (OS are linked to the PFI, all of them improving as the PFI increases. Consequently, there is increasing interest in PFI extension strategies with platinum-free therapeutic options. Such strategies are currently being studied in patients with partially platinum-sensitive disease (PFI 6-12 months, as the treatment of these patients remains clinically challenging. A non-platinum option, trabectedin + pegylated liposomal doxorubicin (PLD combination, has been evaluated in ROC patients in the pivotal phase III OVA-301 study. The OVA-301 study differed from previous trials in the same setting as it included only patients who were not expected to benefit from or who were ineligible for or who were unwilling to receive re-treatment with platinum-based chemotherapy, including those with PPS and PR disease. Subset analysis of patients with PPS disease in OVA-301 showed that the trabectedin + PLD combination significantly improved PFS compared with PLD alone; median PFS 7.4 versus 5.5 months, p=0.0152. Final survival data from the same subset of patients, showed that trabectedin + PLD also achieved a significant 36% decrease in the risk of death compared with PLD alone (HR=0.64; 95% CI, 0.47–0.88; p=0.0027. Median overall survival (OS was 22.4 months in the trabectedin + PLD arm versus 16.4 months in the PLD arm. This represents a statistically significant 6-month improvement in median OS in patients treated with trabectedin + PLD compared to those treated with PLD

  9. Electrochemical behaviour of platinum in hydrogen peroxide solution (1963)

    International Nuclear Information System (INIS)

    Prost, G.H.

    1963-06-01

    The relative stability of hydrogen peroxide in aqueous solution at 25 deg. C, allows its amperometric determination from the theory, using either its cathodic reduction or its anodic oxidation. The cathodic reduction yields a wave on a platinum electrode only when some oxygen is present in the solution. It cannot, therefore, be used for electrochemical determination. On the other hand, the anodic oxidation on platinum produces a wave which might be used. However, a passivation of platinum occurs at the same time. This passivation process is studied by means of potentio-kinetic, potentio-static, intensio-static curves and of pH measurements in the vicinity of the anode. A mechanism for passivation is presented, which takes into account the role of hydrogen peroxide as a reducing agent. This passivation rules out any analytical application of the oxidation reaction of hydrogen peroxide. (author) [fr

  10. Cerium oxide and platinum nanoparticles protect cells from oxidant-mediated apoptosis

    International Nuclear Information System (INIS)

    Clark, Andrea; Zhu Aiping; Sun Kai; Petty, Howard R.

    2011-01-01

    Catalytic nanoparticles represent a potential clinical approach to replace or correct aberrant enzymatic activities in patients. Several diseases, including many blinding eye diseases, are promoted by excessive oxidant stress due to reactive oxygen species (ROS). Cerium oxide and platinum nanoparticles represent two potentially therapeutic nanoparticles that de-toxify ROS. In the present study, we directly compare these two classes of catalytic nanoparticles. Cerium oxide and platinum nanoparticles were found to be 16 ± 2.4 and 1.9 ± 0.2 nm in diameter, respectively. Using surface plasmon-enhanced microscopy, we find that these nanoparticles associate with cells. Furthermore, cerium oxide and platinum nanoparticles demonstrated superoxide dismutase catalytic activity, but did not promote hemolytic or cytolytic pathways in living cells. Importantly, both cerium oxide and platinum nanoparticles reduce oxidant-mediated apoptosis in target cells as judged by the activation of caspase 3. The ability to diminish apoptosis may contribute to maintaining healthy tissues.

  11. A novel reusable platinum nanocatalyst

    International Nuclear Information System (INIS)

    Zhou Weiqiang; Wang Jing; Wang Chuanyi; Du Yukou; Xu Jingkun; Yang Ping

    2010-01-01

    Recyclability of noble metal catalysts is a challenging issue when dealing with their industrial applications. Smart pH-sensitive Pt nanoparticles were successfully prepared for the first time by using octa(N,N-diacetic acid phenylamine)silsesquioxane (OAPAS) as a macromolecular protective agent. As-prepared Pt nanoparticles can self-aggregate or redisperse by only changing the pH of the system solution. In the weak acidic or alkaline solution (pH > 4.0), the Pt nanoparticles dispersed homogenously; while in the acidic solution (pH = 2.5), they self-aggregated. The dynamic self-aggregation and redispersion processes of the Pt nanoparticles driven by pH changes were revealed by transmission electron microscopy measurements. Electrocatalytic experiments proved that the platinum nanoparticles as a recyclable catalyst showed excellent activity for the hydrogenation of aldehyde after runs of five times. Such platinum nanoparticles are thereby anticipated to have great potential functioning as 'smart' catalysts for industrial applications.

  12. Quantitation of pyrimidine dimers in DNA from UVB-irradiated alfalfa (Medicago sativa L.) seedlings

    International Nuclear Information System (INIS)

    Quaite, F.E.; Sutherland, B.M.; Sutherland, J.C.

    1991-01-01

    Depletion of stratospheric ozone will increase the solar ultraviolet radiation in the range from 290-320 nm (UVB) that reaches the surface of the earth, placing an increased UV burden on exposed organisms. One consequence of increased UVB may be decreased productivity of crop plants. A principal lesion caused by UV in DNA is the cyclobutyl pyrimidine dimer. We have adapted a method for measuring these dimers in nanogram quantities of non-radioactive DNA for use in UV-irradiated plants. We find that biologically relevant doses of broad band UVB radiation induce easily detectable frequencies of pyrimidine dimers in the DNA of irradiated alfalfa sprout leaves and that the dose response for dimer formation is linear up to doses of at least 690 J/m 2 . We also find easily measurable frequencies of dimers in the leaves of seedlings grown in glass filtered sunlight but not exposed to additional UVB, suggesting that significant number of dimers are formed in plants exposed to normal sunlight. 27 refs., 3 figs., 1 tab

  13. Stability of Porous Platinum Nanoparticles: Combined In Situ TEM and Theoretical Study

    DEFF Research Database (Denmark)

    Chang, Shery L. Y.; Barnard, Amanda S.; Dwyer, Christian

    2012-01-01

    Porous platinum nanoparticles provide a route for the development of catalysts that use less platinum without sacrificing catalytic performance. Here, we examine porous platinum nanoparticles using a combination of in situ transmission electron microscopy and calculations based on a first-principles......-parametrized thermodynamic model. Our experimental observations show that the initially irregular morphologies of the as-sythesized porous nanoparticles undergo changes at high temperatures to morphologies having faceted external surfaces with voids present in the interior of the particles. The increasing size of stable...

  14. Scaffold hopping from (5-hydroxymethyl) isophthalates to multisubstituted pyrimidines diminishes binding affinity to the C1 domain of protein kinase C.

    Science.gov (United States)

    Provenzani, Riccardo; Tarvainen, Ilari; Brandoli, Giulia; Lempinen, Antti; Artes, Sanna; Turku, Ainoleena; Jäntti, Maria Helena; Talman, Virpi; Yli-Kauhaluoma, Jari; Tuominen, Raimo K; Boije Af Gennäs, Gustav

    2018-01-01

    Protein kinase C (PKC) isoforms play a pivotal role in the regulation of numerous cellular functions, making them extensively studied and highly attractive drug targets. Utilizing the crystal structure of the PKCδ C1B domain, we have developed hydrophobic isophthalic acid derivatives that modify PKC functions by binding to the C1 domain of the enzyme. In the present study, we aimed to improve the drug-like properties of the isophthalic acid derivatives by increasing their solubility and enhancing the binding affinity. Here we describe the design and synthesis of a series of multisubstituted pyrimidines as analogs of C1 domain-targeted isophthalates and characterize their binding affinities to the PKCα isoform. In contrast to our computational predictions, the scaffold hopping from phenyl to pyrimidine core diminished the binding affinity. Although the novel pyrimidines did not establish improved binding affinity for PKCα compared to our previous isophthalic acid derivatives, the present results provide useful structure-activity relationship data for further development of ligands targeted to the C1 domain of PKC.

  15. Unconventional hydrogen bonding to organic ions in the gas phase: Stepwise association of hydrogen cyanide with the pyridine and pyrimidine radical cations and protonated pyridine

    Energy Technology Data Exchange (ETDEWEB)

    Hamid, Ahmed M.; El-Shall, M. Samy, E-mail: mselshal@vcu.edu [Department of Chemistry, Virginia Commonwealth University, Richmond, Virginia 23284 (United States); Hilal, Rifaat; Elroby, Shaaban; Aziz, Saadullah G. [Department of Chemistry, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)

    2014-08-07

    Equilibrium thermochemical measurements using the ion mobility drift cell technique have been utilized to investigate the binding energies and entropy changes for the stepwise association of HCN molecules with the pyridine and pyrimidine radical cations forming the C{sub 5}H{sub 5}N{sup +·}(HCN){sub n} and C{sub 4}H{sub 4}N{sub 2}{sup +·}(HCN){sub n} clusters, respectively, with n = 1–4. For comparison, the binding of 1–4 HCN molecules to the protonated pyridine C{sub 5}H{sub 5}NH{sup +}(HCN){sub n} has also been investigated. The binding energies of HCN to the pyridine and pyrimidine radical cations are nearly equal (11.4 and 12.0 kcal/mol, respectively) but weaker than the HCN binding to the protonated pyridine (14.0 kcal/mol). The pyridine and pyrimidine radical cations form unconventional carbon-based ionic hydrogen bonds with HCN (CH{sup δ+}⋯NCH). Protonated pyridine forms a stronger ionic hydrogen bond with HCN (NH{sup +}⋯NCH) which can be extended to a linear chain with the clustering of additional HCN molecules (NH{sup +}⋯NCH··NCH⋯NCH) leading to a rapid decrease in the bond strength as the length of the chain increases. The lowest energy structures of the pyridine and pyrimidine radical cation clusters containing 3-4 HCN molecules show a strong tendency for the internal solvation of the radical cation by the HCN molecules where bifurcated structures involving multiple hydrogen bonding sites with the ring hydrogen atoms are formed. The unconventional H-bonds (CH{sup δ+}⋯NCH) formed between the pyridine or the pyrimidine radical cations and HCN molecules (11–12 kcal/mol) are stronger than the similar (CH{sup δ+}⋯NCH) bonds formed between the benzene radical cation and HCN molecules (9 kcal/mol) indicating that the CH{sup δ+} centers in the pyridine and pyrimidine radical cations have more effective charges than in the benzene radical cation.

  16. In vitro effects of platinum compounds on renal cellular respiration in mice.

    Science.gov (United States)

    Almarzooqi, Saeeda-S; Alfazari, Ali-S; Abdul-Kader, Hidaya-M; Saraswathiamma, Dhanya; Albawardi, Alia-S; Souid, Abdul-Kader

    2015-01-01

    Cisplatin, carboplatin and oxaliplatin are structurally-related compounds, which are commonly used in cancer therapy. Cisplatin (Platinol(®)) has Boxed Warning stating: "Cumulative renal toxicity associated with PLATINOL is severe", while carboplatin and oxaliplatin are less nephrotoxic. These drugs form platinum adducts with cellular DNA. Their bindings to cellular thiols (e.g., glutathione and metallothionein) are known to contribute to drug resistance while thiol depletion augments platinum toxicity. Using phosphorescence oxygen analyzer, this study investigated the effects of platinum drugs on renal cellular respiration (mitochondrial O2 consumption) in the presence and absence of the thiol blocking agent N-ethylmaleimide (used here as a model for thiol depletion). Renal cellular ATP was also determined. Kidney fragments from C57BL/6 mice were incubated at 37 °C in Krebs-Henseleit buffer (gassed with 95% O2:5% CO2) with and without 100 μM platinum drug in the presence and absence of 100 μM N-ethylmaleimide for ≤ 6 h. Platinum drugs alone had no effects on cellular respiration (P ≥ 0.143) or ATP (P ≥ 0.161). N-ethylmaleimide lowered cellular respiration (P ≤ 0.114) and ATP (P = 0.008). The combination of platinum drug and N-ethylmaleimide significantly lowered both cellular respiration (P ≤ 0.006) and ATP (P ≤ 0.003). Incubations with N-ethylmaleimide alone were associated with moderate-to-severe tubular necrosis. Incubations with cisplatin+N-ethylmaleimide vs. cisplatin alone produced similar severities of tubular necrosis. Tubular derangements were more prominent in carboplatin+N-ethylmaleimide vs. carboplatin alone and in oxaliplatin+N-ethylmaleimide vs. oxaliplatin alone. These results demonstrate the adverse events of thiol depletion on platinum-induced nephrotoxicities. The results suggest cellular bioenergetics is a useful surrogate biomarker for assessing drug-induced nephrotoxicities.

  17. Electrodeposition of platinum metals and alloys from chloride melts

    Directory of Open Access Journals (Sweden)

    Saltykova N.A.

    2003-01-01

    Full Text Available The structure of platinum metals and their alloys deposited by the electrolysis of chloride melts have been investigated. The cathodic deposits were both in the form of compact layers and dendrites. All the alloys of platinum metals obtained are solid solutions in the whole range of composition. Depending on the experimental conditions the layers had columnar, stratum and spiral (dissipative structures. The stratum and dissipative structures were observed in the case of alloys only.

  18. The exchange reaction between deuterium and water vapour on platinum deposited over a hydrophobic support

    International Nuclear Information System (INIS)

    Itsuo, Iida; Junko, Kato; Kenzi, Tamuru

    1977-01-01

    Isotope exchange reaction between deuterium gas and water vapour at room temperature and below on platinum deposited on hydrophobic supports such as polytetrafluoroethylene (PTFE) or Porapak Q (copolymer of styrene and divinylbenzene) was studied and the results were compared with those of the exchange reaction on platinum over hydrophilic support such as alumina. It was demonstrated that the exchange reaction at temperatures below the boiling point of water is markedly retarded by the multilayer adsorption of water over the platinum catalyst deposited on hydrophilic support, whereas the platinum catalyst on hydrophobic support exhibited a high catalytic activity, being not retarded by the water, forming no multilayer of adsorbed water over platinum surface. Therefore in the case of the hydrogen isotope exchange reaction on platinum over hydrophobic support, the chemical exchange rate can be measured even under a saturated vapour pressure of water. The surface area of platinum was estimated by hydrogen chemisorption and hydrogen titration and specific activities of the catalyst were calculated at both room temperature and freezing point of water, which revealed that the specific rate of this reaction does not differ so much over various supports. (orig.) [de

  19. Electrochemical behavior of titanium implanted with platinum

    International Nuclear Information System (INIS)

    Thompson, N.G.; Lichter, B.D.; Appleton, B.R.; Kelly, E.J.; White, C.W.

    1979-01-01

    The following conclusions apply to Ti(Pt) near-surface alloys studied. (1) Open-circuit corrosion measurements show that accumulation of platinum may occur at a surface concentration of 0.32 atomic percent Pt while no accumulation occurs at 0.16 atomic percent Pt. However, these results do not allow a distinction as to cause of accumulation to be made between concentration effects and effects due to the presence of an oxide film. (2) Potentiostatic corrosion at -0.450 V (active corrosion) establish that little or no accumulation of platinum occurs at an oxide-free surface for concentrations less than 0.086 atomic percent Pt; whereas, a large amount of accumulation occurs for a distribution with a peak concentration of 0.83 atomic percent Pt. (3) An initial distribution having a peak concentration of 0.32 atomic percent platinum is sufficient to induce natural passivity in titanium and bring a freely corroding sample to a potential of 0.269 V. This is nearly the applicable reversible potential (-0.260 V) for the hydrogen reaction in 1N H 2 SO 4 . (4) Of three samples which showed accumulation, platinum was eventually lost for two of these samples (0.32 atomic percent, open-circuit corrosion; 0.83 atomic percent, potentiostatic corrosion). The remaining sample (9.1 atomic percent, open-circuit corrosion) maintained the maximum possible potential of -0.260 V for the length of the experiment (approx. 30 days). (5) For samples which had been polarized at -0.300 to -0.340 V and which had eventually reverted to the behavior of pure Ti, post corrosion RBS measurements reveal that a substantial fraction of the Pt fluence is retained on the surface in an electrochemically inactive state

  20. Radiochemical neutron activation analysis of high pure palladium and platinum by ion exchange chromatography

    International Nuclear Information System (INIS)

    Sadikov, I.I.; Zinov'ev, V.G.; Sadikova, Z.O.; Salimov, M.I.

    2006-01-01

    Full text: The palladium and platinum are widely used for jewel manufacture because of their beautiful white color. However the most part of these metals are widely adopted in the world as catalysts. Many works on analytical chemistry of platinum group elements published during last years are devoted to determination of platinum and palladium in other materials. There are no articles on analysis technique of the palladium and platinum purity published during last 20 years. Available publications are very old and are published till 70th of the last century, and implement chemical and spectral methods. At the same time, the palladium and platinum are very suitable for NAA. Therefore the purpose of our research was development of high-sensitivity and multielement techniques of radiochemical neutron activation analysis of a high pure palladium and platinum. Research of nuclear characteristics of palladium and platinum has shown that radioactive nuclides with different yields are formed under the reactor neutrons. 109 , 111 , 111m Pd, 109m , 111 Ag, 191 , 197 , 199 Pt, 199 Au are the most important among them. 109Pd separation factor is equal to 1*10 5 at palladium analysis, whereas 197 Pt and 199 Au separation factor is equal to 1*10 4 at the platinum analysis every other day after irradiation. Palladium and platinum can be separated by precipitation, extraction and ion exchange methods. For separation of radioactive nuclide of the matrix elements from the impurity elements we used ion exchange chromatography system Dowex-1x8 - 1 M HNO 3 for palladium and Dowex-1x8 - 0.1 M HNO 3 for platinum. At the HNO 3 acid concentrations variation from 0,1 M to 1 M more then 25 elements have distribution factors less than 1 and 10 elements have distribution factors 5 while matrix elements have distribution factors higher than 100. It allows an effective separation of these elements from palladium and platinum. Optimum sizes of the chromatographic column and the column effluent

  1. Poly(alizarin red)/Graphene modified glassy carbon electrode for simultaneous determination of purine and pyrimidine

    International Nuclear Information System (INIS)

    Ba Xi; Luo Liqiang; Ding Yaping; Zhang Zhen; Chu Yuliang; Wang Bijun; Ouyang Xiaoqian

    2012-01-01

    Graphical abstract: DPVs of PAR/Graphene/GCE (a) and the bare GCE (c) in 0.1 M PBS containing 50.0 μM G, 50.0 μM A, 100.0 μM T and 100.0 μM C, (b) PAR/Graphene/GCE in 0.1 M PBS. Highlights: ► The sensor exhibited well-separated peaks and low detection limit. ► The sensor possesses high sensitivity and wide linear range. ► The sensor was used for simultaneous detection of G, A, T and C successfully. ► The sensor was applied in a fish sperm DNA sample with satisfactory results. ► The proposed sensor has good stability and reproducibility. - Abstract: In this work, a poly(alizarin red)/Graphene composite film modified glassy carbon electrode (PAR/Graphene/GCE) was prepared for simultaneous determination of four DNA bases (guanine, adenine, thymine and cytosine) without any pretreatment. The morphology and interface property of PAR/Graphene films were examined by scanning electron microscopy and electrochemical impedance spectroscopy. The PAR/Graphene/GCE exhibited excellent electrocatalytic activity toward purine (guanine and adenine) and pyrimidine (thymine and cytosine) in 0.1 M phosphate buffer solution (pH 7.4). Under optimum conditions, differential pulse voltammetry was used to detect the oxidation of purine and pyrimidine. The results showed that PAR/Graphene/GCE exhibited well-separated peaks, low detection limit, high sensitivity and wide linear range for simultaneous detection of purine and pyrimidine. The proposed sensor also has good stability and reproducibility. Furthermore, the modified electrode was applied for the detection of DNA bases in a fish sperm DNA sample with satisfactory results.

  2. Green chemistry: to rethink chemistry for tomorrow's world. Press briefing of 20 January 2015

    International Nuclear Information System (INIS)

    Legrand, Francois

    2015-01-01

    This document discusses various issues related to the development of the green chemistry sector, and mentions and presents activities performed by the CEA in this respect. A first part outlines how green chemistry is an answer to stakes for a sustainable development. The second part addresses metal recycling: recovery of silver from photovoltaic cells, avoiding tensions related to rare earth supply. The third part discusses how to replace dangerous or costly compounds (chromium in aircraft paintings, platinum in fuel cells, ruthenium in photovoltaic cells, rare earth in magnetic wire). The fourth part addresses how to transform wastes into useful products (production of formamides, of aromatic compounds, and of methanol, respectively from waste recycling, natural lignin, and CO_2). The fifth part presents new concepts for chemical synthesis: chemistry under ultrasounds, production of hydrogen from water. The sixth part presents contributions of life sciences to green chemistry: reduction of carbon dioxide emissions, bioremediation (biology for soil rehabilitation), production of molecules of interest by using micro algae, enzymes or bacteria. The last part discusses issues which outline that chemistry is at the heart of challenges for a sustainable nuclear in terms of materials, for a closed fuel cycle, in terms of fuel cycle processes, of installation sanitation and dismantling. Appendices formulate 5 societal challenges for green chemistry, and 12 background principles of green chemistry

  3. A combined radiation and platinum chemotherapy for esophageal carcinoma

    International Nuclear Information System (INIS)

    Takamura, Akio; Saito, Hiroya; Sakurai, Yasuo; Horio, Keiji; Mizoe, Junetsu.

    1993-01-01

    The prognosis of the patients with advanced esophageal carcinoma treated by definitive radiotherapy is still dismal with a reported 5-year survival rate of 5-10% in most series. Since 1986, combined radiotherapy with chemotherapy using platinum analogue was initiated at Asahikawa and Obihiro Kosei Hospitals in order to improve local-regional control and the survival of the patients. From 1980 to 1992, 81 patients with unresectable esophageal carcinoma were treated with radiotherapy. Since April 1986, 37 out of the 81 patients received both radiotherapy and chemotherapy with platinum. Platinum was used during the course of radiotherapy. The method of administration of platinum was as follows; Cisplatin intravenously (50 mg, weekly, total 200 mg) in 9 patients, Carboplatin intravenously (100-150 mg, weekly, total 400-900 mg) in 11 patients and Cisplatin intraarterially (100 mg, at a 3-4 week interval, total 100-300 mg) in 17 patients. These 37 patients (Group A) were compared to 44 patients treated by radiotherapy alone (Group B) with respect to initial response and survival rate. Response was defined according to the guidelines recommended by Japanese Society for Esophageal Diseases. Response rates were 59.1% (19 CR and 7 PR) in Group B and 70.3% (7 CR and 19 PR) in Group A. Primary relapse-free rates were 36.4% in Group B and 37.8% in Group A. The cumulative survival at 3 years were 11.7% in Group B and 10.6% in Group A. Enhancement of side effects by chemotherapy was minimal and acceptable. Improvement of local-regional control and survival was not obvious by adding a concomitant platinum-chemotherapy. A definite conclusion, however, could not be drawn because of the retrospective, non-controlled nature of this study. Introduction of more intensive, multiple agents chemotherapy seems necessary if one aims at improving the results. (author)

  4. Electrochemical and microstructural characterization of platinum supported on glassy carbon

    Directory of Open Access Journals (Sweden)

    Terzić Sanja

    2007-01-01

    Full Text Available The effect of the electrochemical oxidation of glassy carbon on the deposition of platinum particles and the electrocatalytic activity of platinum supported on oxidized glassy carbon were studied for methanol oxidation in H2SO4 solution. Platinum was potentiostatically deposited from H2SO4 + 6mM H2PtCl6 solution. Glassy carbon was anodically polarized in 1 M NaOH at 1.41 V (SCE for 35 and 95 s and in 0.5 M H2SO4 at 2V (SCE for 35; 95 s and 2.25 V for 35 and 95 s. Electrochemical treatment of the GC support leads to a better distribution of platinum on the substrate and has remarkable effect on the activity. The activity of the Pt/GCox electrode for methanol oxidation is larger than that of polycrystalline Pt and by more than one order of magnitude larger than that of a Pt/GC electrode. This increase in activity indicates the pronounced role of the organic residues of the GC support on the properties of Pt particles deposited on glassy carbon.

  5. Enhancement of micropore filling of water on carbon black by platinum loading

    Energy Technology Data Exchange (ETDEWEB)

    Miyajima, Naoya, E-mail: miyajima@yamanashi.ac.jp [Interdisciplinary Graduate School of Medicine and Engineering, 4-3-11 Takeda, Kofu, Yamanashi 400-8511 (Japan); Hatori, Hiroaki [Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan); Radovic, Ljubisa R. [Department of Energy and Geo-Environmental Engineering, The Pennsylvania State University, University Park, PA 16802 (United States); Yamada, Yoshio [Institute of Advanced Industrial Science and Technology (AIST), 16-1 Onogawa, Tsukuba, Ibaraki 305-8569 (Japan)

    2010-10-15

    Two kinds of typical carbons, carbon black and activated carbon fibers, were modified with platinum nanoparticles without changing their original pore structures. The surface properties of the modified carbons were investigated by measuring of water adsorption isotherms. Micropore filling of water was facilitated by the presence of platinum nanoparticles on the surface of the carbon black. On the other hand, such a filling effect was not observed in the case of the activated carbon fibers. A critical content and/or size of platinum nanoparticles could be required to promote efficiently the water adsorption.

  6. BOWIEITE: A NEW RHODIUM-IRIDIUM-PLATINUM SULFIDE IN PLATINUM-ALLOY NUGGETS, GOODNEWS BAY, ALASKA.

    Science.gov (United States)

    Desborough, George A.; Criddle, Alan J.

    1984-01-01

    Bowieite (Rh,Ir,Pt)//2S//3, a new mineral species, is found in three nuggets of platinum from Goodnews Bay, Alaska. In linearly polarized reflected light, and compared to the host, higher reflecting white platinum-iridium alloy, bowieite is pale gray to pale gray-brown; neither bireflectance nor reflectance pleochroism is apparent. With polars crossed, its anisotropic rotation tints vary from gray to dark brown. Luminance values (relative to the CIE illuminant C) for R//1 and R//2, computed from full spectral data for the most bireflectant grain, are 45. 8% and 48. 2% in air, and 30. 5% and 33. 0% in oil, respectively. VHN//1//0//0 1288 (858 to 1635). Bowieite is orthorhombic, space group Pnca, with a 8. 454(7) -8. 473(8), b 5. 995(1)-6. 002(7), c 6. 143(1)-6. 121(8) A, Z equals 4. Some grains that are 2. 6 to 3. 8 atomic % metal-deficient occur as an optically coherent rim on bowieite; the rim and the bowieite grain are not optically continuous.

  7. On the enzymatic formation of platinum nanoparticles

    International Nuclear Information System (INIS)

    Govender, Y.; Riddin, T. L.; Gericke, M.; Whiteley, C. G.

    2010-01-01

    A dimeric hydrogenase enzyme (44.5 and 39.4 kDa sub units) was isolated in a 39.5% yield from the fungus Fusarium oxysporum and purified 4.64-fold by ion exchange chromatography on Sephacryl S-200. Characterisation of the enzyme afforded pH and temperature optima of 7.5 and 38 o C, respectively, a half-life stability of 36 min and a V max and K m of 3.57 nmol min -1 mL -1 and 2.25 mM, respectively. This enzyme was inhibited (non-competitively) by hydrogen hexachloroplatinic acid (H 2 PtCl 6 ) at 1 or 2 mM with a K i value of 118 μM. Incubation of the platinum salt with the pure enzyme under an atmosphere of hydrogen and optimum enzyme conditions (pH 7.5, 38 o C) afforded o C) over 90% reduction took place after the same length of time. Cell-free extract from the fungal isolates produced nearly 90% bioreduction of the platinum salt under both pH and temperature conditions. The bioreduction of the platinum salt by a hydrogenase enzyme takes place by a passive process and not an active one as previously understood.

  8. The EGF repeat-specific O-GlcNAc-transferase Eogt interacts with notch signaling and pyrimidine metabolism pathways in Drosophila.

    Directory of Open Access Journals (Sweden)

    Reto Müller

    Full Text Available The O-GlcNAc transferase Eogt modifies EGF repeats in proteins that transit the secretory pathway, including Dumpy and Notch. In this paper, we show that the Notch ligands Delta and Serrate are also substrates of Eogt, that mutation of a putative UDP-GlcNAc binding DXD motif greatly reduces enzyme activity, and that Eogt and the cytoplasmic O-GlcNAc transferase Ogt have distinct substrates in Drosophila larvae. Loss of Eogt is larval lethal and disrupts Dumpy functions, but does not obviously perturb Notch signaling. To identify novel genetic interactions with eogt, we investigated dominant modification of wing blister formation caused by knock-down of eogt. Unexpectedly, heterozygosity for several members of the canonical Notch signaling pathway suppressed wing blister formation. And importantly, extensive genetic interactions with mutants in pyrimidine metabolism were identified. Removal of pyrimidine synthesis alleles suppressed wing blister formation, while removal of uracil catabolism alleles was synthetic lethal with eogt knock-down. Therefore, Eogt may regulate protein functions by O-GlcNAc modification of their EGF repeats, and cellular metabolism by affecting pyrimidine synthesis and catabolism. We propose that eogt knock-down in the wing leads to metabolic and signaling perturbations that increase cytosolic uracil levels, thereby causing wing blister formation.

  9. Ultraviolet-endonuclease activity in cell extracts of Saccharomyces cerevisiae mutants defective in excision of pyrimidine dimers

    International Nuclear Information System (INIS)

    Bekker, M.L.; Kaboev, O.K.; Akhmedov, A.T.; Luchkina, L.A.

    1980-01-01

    Cell-free extracts of ultraviolet-sensitive mutants of Saccharomyces cerevisiae defective in excision of pyrimidine dimers, rad1, rad2, rad3, rad4, rad10, and rad16, as well as the extracts of the wild-type strain RAD+, display ultraviolet-endonuclease activity

  10. Electrochemical DNA biosensors based on platinum nanoparticles combined carbon nanotubes

    International Nuclear Information System (INIS)

    Zhu Ningning; Chang Zhu; He Pingang; Fang Yuzhi

    2005-01-01

    Platinum nanoparticles were used in combination with multi-walled carbon nanotubes (MWCNTs) for fabricating sensitivity-enhanced electrochemical DNA biosensor. Multi-walled carbon nanotubes and platinum nanoparticles were dispersed in Nafion, which were used to fabricate the modification of the glassy carbon electrode (GCE) surface. Oligonucleotides with amino groups at the 5' end were covalently linked onto carboxylic groups of MWCNTs on the electrode. The hybridization events were monitored by differential pulse voltammetry (DPV) measurement of the intercalated daunomycin. Due to the ability of carbon nanotubes to promote electron-transfer reactions, the high catalytic activities of platinum nanoparticles for chemical reactions, the sensitivity of presented electrochemical DNA biosensors was remarkably improved. The detection limit of the method for target DNA was 1.0 x 10 -11 mol l -1

  11. Discovery of the calcium, indium, tin, and platinum isotopes

    International Nuclear Information System (INIS)

    Amos, S.; Gross, J.L.; Thoennessen, M.

    2011-01-01

    Currently, twenty-four calcium, thirty-eight indium, thirty-eight tin, and thirty-nine platinum isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented. - Highlights: Documentation of the discovery of all calcium, indium, tin and platinum isotopes. → Summary of author, journal, year, place and country of discovery for each isotope. → Brief description of discovery history of each isotope.

  12. The relationship between debt levels and total shareholder return of JSE-listed platinum companies

    Directory of Open Access Journals (Sweden)

    Sandra Jooste

    2016-02-01

    Full Text Available The purpose of this study is to investigate empirically whether there is a positive correlation between debt levels and total shareholder return (TSR of platinum JSE-listed companies. The study field comprised annual analyses for 12 companies listed under the Platinum and Precious Metals sector on the JSE Ltd for the 14-year period 2000 to 2013. The results of the study were inconclusive as a statistically significant positive correlation between changes in debt levels and changes in TSR could only be found in two of these years. The core audience of the study will be the management of South African platinum companies considering changes in their capital structure, and investors considering investment in a listed platinum company. The contribution of the study is therefore to add to the body of literature on capital structure decisions from a South African platinum mine context

  13. Characterization, non-isothermal decomposition kinetics and photocatalytic water splitting of green chemically synthesized polyoxoanions of molybdenum containing phosphorus as hetero atom

    International Nuclear Information System (INIS)

    D’Cruz, Bessy; Samuel, Jadu; George, Leena

    2014-01-01

    Highlights: • CPM nanorods were synthesized by applying the principles of green chemistry. • The isoconversional method was used to analyze the effective activation energy. • The appropriate reaction models of the two decomposition stages were determined. • Photocatalytic water splitting was investigated in the presence of platinum co-catalyst. - Abstract: In here, the green synthesis and thermal characterization of a novel polyoxoanions of molybdenum containing phosphorus as hetero atom are reported. The composition and morphology of the nanorods were established by fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and inductively coupled plasma atomic emission spectroscopic (ICP-AES) techniques. Thermal properties of the nanoparticles were investigated by non-isothermal analysis under nitrogen atmosphere. The values activation energy of each stage of thermal decomposition for all heating rates was calculated by Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunnose (KAS) methods. Invariant kinetic parameter (IKP) method and master plot method were also used to evaluate the kinetic parameters and mechanism for the thermal decomposition of cetylpyridinium phosphomolybdate (CPM). Photocatalytic water oxidation mechanism using CPM catalyst in the presence of platinum (Pt) co-catalyst enhances the H 2 evolution and was found to be 1.514 mmol/g/h

  14. Characterization, non-isothermal decomposition kinetics and photocatalytic water splitting of green chemically synthesized polyoxoanions of molybdenum containing phosphorus as hetero atom

    Energy Technology Data Exchange (ETDEWEB)

    D’Cruz, Bessy [Department of Chemistry, Mar Ivanios College, Thiruvananthapuram 695015 (India); Samuel, Jadu, E-mail: jadu_samuel@yahoo.co.in [Department of Chemistry, Mar Ivanios College, Thiruvananthapuram 695015 (India); George, Leena [Catalysis and Inorganic Chemistry Division, National Chemical Laboratory, Pune 411008 (India)

    2014-11-20

    Highlights: • CPM nanorods were synthesized by applying the principles of green chemistry. • The isoconversional method was used to analyze the effective activation energy. • The appropriate reaction models of the two decomposition stages were determined. • Photocatalytic water splitting was investigated in the presence of platinum co-catalyst. - Abstract: In here, the green synthesis and thermal characterization of a novel polyoxoanions of molybdenum containing phosphorus as hetero atom are reported. The composition and morphology of the nanorods were established by fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA) and inductively coupled plasma atomic emission spectroscopic (ICP-AES) techniques. Thermal properties of the nanoparticles were investigated by non-isothermal analysis under nitrogen atmosphere. The values activation energy of each stage of thermal decomposition for all heating rates was calculated by Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunnose (KAS) methods. Invariant kinetic parameter (IKP) method and master plot method were also used to evaluate the kinetic parameters and mechanism for the thermal decomposition of cetylpyridinium phosphomolybdate (CPM). Photocatalytic water oxidation mechanism using CPM catalyst in the presence of platinum (Pt) co-catalyst enhances the H{sub 2} evolution and was found to be 1.514 mmol/g/h.

  15. Oscillatory instabilities in the electrooxidation of borohydride on platinum

    Energy Technology Data Exchange (ETDEWEB)

    Machado, Eduardo G.; Varela, Hamilton, E-mail: varela@iqsc.usp.br [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Instituto de Quimica

    2014-03-15

    The borohydride ion has been pointed as a promising alternative fuel. Most of the investigation on its electrochemistry is devoted to the electrocatalytic aspects of its electrooxidation on platinum and gold surfaces. Besides the known kinetic limitations and intricate mechanism, our Group has recently found the occurrence of two regions of bi-stability and autocatalysis in the electrode potential during the open circuit interaction of borohydride and oxidized platinum surfaces. Following this previous contribution, the occurrence of more complicated phenomena is here presented: namely the presence of electrochemical oscillations during the electrooxidation of borohydride on platinum in alkaline media. Current oscillations were found to be associated to two distinct instability windows and characterized in the resistance-potential parameter plane. The dynamic features of such oscillations suggest the existence of distinct mechanisms according to the potential region. Previously published results obtained under non-oscillatory regime were used to give some hints on the surface chemistry behind the observed dynamics. (author)

  16. Platinum-induced structural collapse in layered oxide polycrystalline films

    International Nuclear Information System (INIS)

    Wang, Jianlin; Liu, Changhui; Huang, Haoliang; Fu, Zhengping; Peng, Ranran; Zhai, Xiaofang; Lu, Yalin

    2015-01-01

    Effect of a platinum bottom electrode on the SrBi 5 Fe 1−x Co x Ti 4 O 18 layered oxide polycrystalline films was systematically studied. The doped cobalt ions react with the platinum to form a secondary phase of PtCoO 2 , which has a typical Delafossite structure with a weak antiferromagnetism and an exceptionally high in-plane electrical conductivity. Formation of PtCoO 2 at the interface partially consumes the cobalt dopant and leads to the structural collapsing from 5 to 4 layers, which was confirmed by X-ray diffraction and high resolution transmission electron microscopy measurements. Considering the weak magnetic contribution from PtCoO 2 , the observed ferromagnetism should be intrinsic of the Aurivillius compounds. Ferroelectric properties were also indicated by the piezoresponse force microscopy. In this work, the platinum induced secondary phase at the interface was observed, which has a strong impact on Aurivillius structural configuration and thus the ferromagnetic and ferroelectric properties

  17. VB Platinum Tile & Carpet, Inc. Information Sheet

    Science.gov (United States)

    VB Platinum Tile & Carpet, Inc. (the Company) is located in Bristow, Virginia. The settlement involves renovation activities conducted at a property constructed prior to 1978, located in Washington, DC.

  18. Platinum group metal nitrides and carbides: synthesis, properties and simulation

    International Nuclear Information System (INIS)

    Ivanovskii, Alexander L

    2009-01-01

    Experimental and theoretical data on new compounds, nitrides and carbides of the platinum group 4d and 5d metals (ruthenium, rhodium, palladium, osmium, iridium, platinum), published over the past five years are summarized. The extreme mechanical properties of platinoid nitrides and carbides, i.e., their high strength and low compressibility, are noted. The prospects of further studies and the scope of application of these compounds are discussed.

  19. Hydroxylamine electrochemistry at low-index single-crystal platinum electrodes in acidic media

    NARCIS (Netherlands)

    Rosca, V.; Beltramo, G.L.; Koper, M.T.M.

    2004-01-01

    The electrochemistry of hydroxylamine at low-index single-crystal platinum electrodes in acidic media has been studied by voltammetry and in-situ FTIRRAS. Hydroxylamine (HAM) reactivity at platinum is largely controlled by interaction of the other components of the solution or products of the HAM

  20. Ethanol oxidation on a nichrome-supported spherical platinum microparticle electrocatalyst prepared by electrodeposition

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Zhen-Hui; Li, Jing; Dong, Xiaoya; Wang, Dong; Chen, Tiwei; Qiao, Haiyan; Huang, Aiping [College of Chemistry and Environmental Science, Henan Key Laboratory for Environmental Pollution Control, Henan Normal University, Jianshe Road, Xinxiang 453007 (China)

    2008-11-15

    A novel electrode was rapidly prepared by depositing microparticle platinum onto a nichrome substrate in dilute chloroplatinic acid solution by cyclic voltammetry. The SEM results revealed that the deposits were composed of spherical Pt microparticles. Cyclic voltammetry and chronoamperometry were used for the characterization of the electrodes. Results of the electrochemical measurements showed that the spherical Pt microparticle electrodes retained the properties of metal platinum, increased the catalytic activity and promoted the electrocatalytic oxidation of ethanol. Moreover, the deposited Pt microparticles improved the electrochemical properties of the support material and reduced the dosage of noble metal platinum remarkably. The cost could be reduced dramatically by decreasing the contents of platinum. The spherical Pt microparticles deposited on the nichrome supports are likely a potential electrocatalyst for ethanol electrooxidation. (author)

  1. Synthesis and biological evaluation of new pyrazolo[3,4-d]pyrimidine derivatives

    Directory of Open Access Journals (Sweden)

    Asma Agrebi

    2014-05-01

    Full Text Available Several new pyrazolopyrimidine compounds were achieved from aminocyanopyarazole 1. The starting material 1 was initially coupled with orthoester at refluxed with various primary amines, ammonia, hydrazines and hydroxylamine to furnish a series of pyrazolo[3,4-d]pyrimidines. The reaction of imidate 2a-b with hydrazide derivatives led to the formation of pyrazolo[3,4-d][1,2,4]triazolo[4,3-c]pyrimidines. Some of the synthesized compounds 3a and 4c were evaluated for their anti-inflammatory, antipyretic and nociceptive activities. We start by studing the toxicity of these two molecules by measuring the corresponding DL50. The DL50 of 3a and 4c are estimated to 1333.2mg / kg and 1593.5mg / kg respectively. Pharmacological evaluation showed that compounds 3a and 4c at doses (5.5-22.2 mg / Kg, i.p exhibited anti-inflammatory activities compared to Ibuprofen (150 mg / Kg, i.p, used as a refer ence drug. Further, our study showed that the injection of derived pyrazolopyrimidines on hyperthermic animal leads to a decrease in temperature after 1 hours of treatment compared to paracetamol used as reference. In addition, the injection of derived pyrazolopyrimidines at different doses contains a potent nociceptive activity. This effect is dose-dependent compared to aspirin.

  2. Simultaneous establishment of monoclonal antibodies specific for either cyclobutane pyrimidine dimer or (6-4)photoproduct from the same mouse immunized with ultraviolet irradiated DNA

    International Nuclear Information System (INIS)

    Mori, Toshio; Nakane, Misa; Hattori, Tsuyoshi; Matsunaga, Tsukasa; Nikaido, Osamu; Ihara, Makoto

    1991-01-01

    Six new monoclonal antibodies (TDM-2, TDM-3, 64M-2, 64M-3 64M-4 and 64M-5) specific for ultraviolet (UV) induced DNA damage have been established. In the antibody characterization experiments, two TDM antibodies were found to show a dose-dependent binding to UV-irradiated DNA (UV-DNA), decrease of binding to UV-DNA after cyclobutane pyrimidine dimer photoreactivation, binding to DNA containing cyclobutane thymine dimers, and unchanged binding to UV-DNA after photoisomerization of (6-4)photoproducts to Dewar photoproducts. These results indicated that the epitope of TDM monoclonal antibodies was the cyclobutane pyrimidine dimer in DNA. On the other hand, four 64M antibodies were found to show a dose-dependent binding to UV-DNA, unchanged binding to UV-DNA after cyclobutane pyrimidine dimer photoreactivation, undetectable binding to DNA containing thymine dimers, and decrease of binding to UV-DNA after photoisomerization of (6-4)photoproducts. These results indicated that the epitope of 64M antibodies was the (6-4)photoproduct in DNA. This is the first report of the simultaneous establishment of monoclonal antibodies against the two different types of photolesions from the same mouse. By using these monoclonal antibodies, we have succeeded in measuring both cyclobutane pyrimidine dimers and (6-4)photoproducts in the DNA from human primary cells irradiated with physiological UV doses. (author)

  3. Cyclobutane pyrimidine dimers are photosensitised by carprofen plus UVA in human HaCaT cells.

    Science.gov (United States)

    Robinson, K S; Traynor, N J; Moseley, H; Ferguson, J; Woods, J A

    2010-06-01

    Every year in the UK about 75,000 cases of non-melanoma skin cancer (NMSC) are registered, and about 9500 people are diagnosed with cutaneous melanoma (CM). The main risk factor for these cancers is exposure to sunlight. The effects of light on skin are wavelength dependent, with wavelengths in the UVB waveband (280-315 nm) being the most carcinogenic. UVB is directly absorbed by DNA, producing dimeric pyrimidine photoproducts including cyclobutane pyrimidine dimers (CPD) and pyrimidine (6-4) pyrimodone photoproducts (6-4PP). However UVA (315-400 nm) can also produce CPD, induce skin tumours in mice, and has been shown to be mutagenic in cell culture. Although the precise role of UVA in human skin cancer remains to be elucidated, it comprises the major portion of solar UV radiation, transmits through window glass and can be delivered in high doses from tanning lamps. Non-steroidal anti-inflammatory drugs (NSAIDs), in particular the 2-aryl propionic acid derivatives, are a well-documented group of photosensitising chemicals producing clinical phototoxic and photoallergic reactions. We have used carprofen, a model compound from this group to see if it could amplify the effects of UVA and contribute to the formation of CPD by UVA. Preliminary work has shown that carprofen combined with low doses of UVA (lambda(max): 365 nm; 5 J/cm(2)) can produce both strand breaks (SB) and CPD in human skin or blood cells. CPD were detected indirectly by both an immunofluorescence method and as T4 endonuclease V sensitive sites in the comet assay. These findings show that compounds other than fluoroquinolones and psoralen derivatives may contribute to CPD formation in skin cells in combination with UVA. Copyright 2010 Elsevier Ltd. All rights reserved.

  4. Poly(alizarin red)/Graphene modified glassy carbon electrode for simultaneous determination of purine and pyrimidine

    Energy Technology Data Exchange (ETDEWEB)

    Ba Xi; Luo Liqiang [Department of Chemistry, Shanghai University, Shanghai 200444 (China); Ding Yaping, E-mail: wdingyp@sina.com [Department of Chemistry, Shanghai University, Shanghai 200444 (China); Zhang Zhen [Department of Chemistry, Shanghai University, Shanghai 200444 (China); Chu Yuliang [Instrumental Analysis and Research Center, Shanghai University, Shanghai 200444 (China); Wang Bijun; Ouyang Xiaoqian [Department of Chemistry, Shanghai University, Shanghai 200444 (China)

    2012-11-08

    Graphical abstract: DPVs of PAR/Graphene/GCE (a) and the bare GCE (c) in 0.1 M PBS containing 50.0 {mu}M G, 50.0 {mu}M A, 100.0 {mu}M T and 100.0 {mu}M C, (b) PAR/Graphene/GCE in 0.1 M PBS. Highlights: Black-Right-Pointing-Pointer The sensor exhibited well-separated peaks and low detection limit. Black-Right-Pointing-Pointer The sensor possesses high sensitivity and wide linear range. Black-Right-Pointing-Pointer The sensor was used for simultaneous detection of G, A, T and C successfully. Black-Right-Pointing-Pointer The sensor was applied in a fish sperm DNA sample with satisfactory results. Black-Right-Pointing-Pointer The proposed sensor has good stability and reproducibility. - Abstract: In this work, a poly(alizarin red)/Graphene composite film modified glassy carbon electrode (PAR/Graphene/GCE) was prepared for simultaneous determination of four DNA bases (guanine, adenine, thymine and cytosine) without any pretreatment. The morphology and interface property of PAR/Graphene films were examined by scanning electron microscopy and electrochemical impedance spectroscopy. The PAR/Graphene/GCE exhibited excellent electrocatalytic activity toward purine (guanine and adenine) and pyrimidine (thymine and cytosine) in 0.1 M phosphate buffer solution (pH 7.4). Under optimum conditions, differential pulse voltammetry was used to detect the oxidation of purine and pyrimidine. The results showed that PAR/Graphene/GCE exhibited well-separated peaks, low detection limit, high sensitivity and wide linear range for simultaneous detection of purine and pyrimidine. The proposed sensor also has good stability and reproducibility. Furthermore, the modified electrode was applied for the detection of DNA bases in a fish sperm DNA sample with satisfactory results.

  5. Fabrication of three-dimensional platinum microstructures with laser irradiation and electrochemical technique

    International Nuclear Information System (INIS)

    Kikuchi, T.; Takahashi, H.; Maruko, T.

    2007-01-01

    Three-dimensional (3D) platinum microstructures were fabricated by successive procedures: aluminum anodizing, laser irradiation, nickel/platinum electroplating, and removal of the aluminum substrate, the oxide films, and the nickel metal layer. Aluminum plates and rods were anodized in an oxalic acid solution to form porous type oxide films. The anodized specimens were immersed in a nickel electroplating solution, and then irradiated with a pulsed Nd-yttrium aluminum garnet (YAG) laser beam to remove the anodic oxide film with a three-dimensional XYZθ stage. The specimens were cathodically polarized in the nickel and a platinum electroplating solution to form the metal micropattern at the laser-irradiated area. The electroplated specimens were immersed in NaOH solution to dissolve the aluminum substrate and the oxide films, and then immersed in HCl solution to dissolve the nickel deposits. A platinum grid-shaped microstructure, a microspring, and a cylindrical network microstructure with 50-100 μm line width were obtained successfully

  6. Fabrication of three-dimensional platinum microstructures with laser irradiation and electrochemical technique

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, T. [Graduate School of Engineering, Hokkaido University, N13, W8, Kita-Ku, Sapporo (Japan)]. E-mail: kiku@elechem1-mc.eng.hokudai.ac.jp; Takahashi, H. [Graduate School of Engineering, Hokkaido University, N13, W8, Kita-Ku, Sapporo (Japan); Maruko, T. [Furuya Metal Co. Ltd., R and D Group, Shimodate Daiichi Kogyodanchi 1915, Morisoejima, Chikusei, Ibaraki (Japan)

    2007-02-01

    Three-dimensional (3D) platinum microstructures were fabricated by successive procedures: aluminum anodizing, laser irradiation, nickel/platinum electroplating, and removal of the aluminum substrate, the oxide films, and the nickel metal layer. Aluminum plates and rods were anodized in an oxalic acid solution to form porous type oxide films. The anodized specimens were immersed in a nickel electroplating solution, and then irradiated with a pulsed Nd-yttrium aluminum garnet (YAG) laser beam to remove the anodic oxide film with a three-dimensional XYZ{theta} stage. The specimens were cathodically polarized in the nickel and a platinum electroplating solution to form the metal micropattern at the laser-irradiated area. The electroplated specimens were immersed in NaOH solution to dissolve the aluminum substrate and the oxide films, and then immersed in HCl solution to dissolve the nickel deposits. A platinum grid-shaped microstructure, a microspring, and a cylindrical network microstructure with 50-100 {mu}m line width were obtained successfully.

  7. Determination of phosphorus traces in platinum alloys by two-phase isotope exchange

    International Nuclear Information System (INIS)

    Vlacil, F.

    1980-01-01

    The method of ZEMAN and KRATZER for the determination of phosphorus traces by means of two-phase isotope exchange was modified for the determination of phosphorus in pure platinum or pure platinum alloys. It was found that Pt, Rh, Ag and As do not interfere with the determination. Among the elements usually present in platinum metal or platinum alloys, only gold interferes. It was removed by extraction from 7M HCl by MIBK and AmOAc. Hydrochloric acid also interferes but it can be removed by evaporation. The analytical procedure is given for the solution obtained by pressure decomposition of the sample (0.5 g) in a steel bomb with PTFE inlay. It is possible to determine > 2 ppm P (approximate error -10%). If using calibration dependence instead of the well known equation for isotope exchange it is not necessary to know the content of P in the standard solution labelled with 32 P. (author)

  8. Preparation and Analysis of Platinum Thin Films for High Temperature Sensor Applications

    Science.gov (United States)

    Wrbanek, John D.; Laster, Kimala L. H.

    2005-01-01

    A study has been made of platinum thin films for application as high temperature resistive sensors. To support NASA Glenn Research Center s high temperature thin film sensor effort, a magnetron sputtering system was installed recently in the GRC Microsystems Fabrication Clean Room Facility. Several samples of platinum films were prepared using various system parameters to establish run conditions. These films were characterized with the intended application of being used as resistive sensing elements, either for temperature or strain measurement. The resistances of several patterned sensors were monitored to document the effect of changes in parameters of deposition and annealing. The parameters were optimized for uniformity and intrinsic strain. The evaporation of platinum via oxidation during annealing over 900 C was documented, and a model for the process developed. The film adhesion was explored on films annealed to 1000 C with various bondcoats on fused quartz and alumina. From this compiled data, a list of optimal parameters and characteristics determined for patterned platinum thin films is given.

  9. Uridine 5′-Monophosphate Synthase Is Transcriptionally Regulated by Pyrimidine Levels in Nicotiana plumbaginifolia1

    Science.gov (United States)

    Santoso, Djoko; Thornburg, Robert

    1998-01-01

    To understand the regulation and expression of pyrimidine biosynthesis in plants, we have examined the effect of the metabolic inhibitor 5-fluoroorotic acid (FOA) on uridine-5′-monophosphate synthase (UMPSase) expression in cell cultures of Nicotiana plumbaginifolia. UMPSase is the rate-limiting step of pyrimidine biosynthesis in plants. Addition of FOA causes an up-regulation of UMPSase enzyme activity in cell cultures after a lag phase of several days. Western-blot analysis demonstrated that the up-regulation in enzyme activity was caused by increased expression of the UMPSase protein. Northern-blot analysis demonstrated a higher level of UMPSase mRNA in the FOA-induced tissues than in control tissues. Run-on transcriptional assays showed that the UMPSase gene was transcriptionally activated after FOA treatment. The mechanism of toxicity of FOA is through thymine starvation. We found that addition of thymine abrogated the FOA-mediated up-regulation of UMPSase. In addition, methotrexate and aminopterin, which affect thymine levels by inhibiting dihydrofolate reductase, also up-regulate UMPSase in N. plumbaginifolia cells. PMID:9490773

  10. Determination of microquantities of silver in platinum by isotope dilution

    International Nuclear Information System (INIS)

    Yedinakova, V.; Sladkovska, Y.

    1980-01-01

    A method is described for determining microquantities of silver in platinum. It is based on isotope dilution by means of substoichiometric extraction of dithizonates with carbon tetrachloride. The determination of silver according to this technique is not interfered by zinc or gold in quantities exceeding the silver content by one order of magnitude nor by a great excess of platinum. In the presence of copper the addition of complexon is necessary. (author)

  11. Melting behaviour of gold-platinum nanoalloy clusters by molecular dynamics simulations

    Energy Technology Data Exchange (ETDEWEB)

    Ong, Yee Pin; Yoon, Tiem Leong [School of Physics, Universiti Sains Malaysia, 11800 USM, Penang (Malaysia); Lim, Thong Leng [Faculty of Engineering and Technology, Multimedia University, Melaka Campus, 75450 Melaka (Malaysia)

    2015-04-24

    The melting behavior of bimetallic gold-platinum nanoclusters is studied by applying Brownian-type isothermal molecular dynamics (MD) simulation, a program modified from the cubic coupling scheme (CCS). The process begins with the ground-state structures obtained from global minimum search algorithm and proceeds with the investigation of the effect of temperature on the thermal properties of gold-platinum nanoalloy clusters. N-body Gupta potential has been employed in order to account for the interactions between gold and platinum atoms. The ground states of the nanoalloy clusters, which are core-shell segregated, are heated until they become thermally segregated. The detailed melting mechanism of the nanoalloy clusters is studied via this approach to provide insight into the thermal stability of the nanoalloy clusters.

  12. Aberrant DNA damage response pathways may predict the outcome of platinum chemotherapy in ovarian cancer.

    Directory of Open Access Journals (Sweden)

    Dimitra T Stefanou

    Full Text Available Ovarian carcinoma (OC is the most lethal gynecological malignancy. Despite the advances in the treatment of OC with combinatorial regimens, including surgery and platinum-based chemotherapy, patients generally exhibit poor prognosis due to high chemotherapy resistance. Herein, we tested the hypothesis that DNA damage response (DDR pathways are involved in resistance of OC patients to platinum chemotherapy. Selected DDR signals were evaluated in two human ovarian carcinoma cell lines, one sensitive (A2780 and one resistant (A2780/C30 to platinum treatment as well as in peripheral blood mononuclear cells (PBMCs from OC patients, sensitive (n = 7 or resistant (n = 4 to subsequent chemotherapy. PBMCs from healthy volunteers (n = 9 were studied in parallel. DNA damage was evaluated by immunofluorescence γH2AX staining and comet assay. Higher levels of intrinsic DNA damage were found in A2780 than in A2780/C30 cells. Moreover, the intrinsic DNA damage levels were significantly higher in OC patients relative to healthy volunteers, as well as in platinum-sensitive patients relative to platinum-resistant ones (all P<0.05. Following carboplatin treatment, A2780 cells showed lower DNA repair efficiency than A2780/C30 cells. Also, following carboplatin treatment of PBMCs ex vivo, the DNA repair efficiency was significantly higher in healthy volunteers than in platinum-resistant patients and lowest in platinum-sensitive ones (t1/2 for loss of γH2AX foci: 2.7±0.5h, 8.8±1.9h and 15.4±3.2h, respectively; using comet assay, t1/2 of platinum-induced damage repair: 4.8±1.4h, 12.9±1.9h and 21.4±2.6h, respectively; all P<0.03. Additionally, the carboplatin-induced apoptosis rate was higher in A2780 than in A2780/C30 cells. In PBMCs, apoptosis rates were inversely correlated with DNA repair efficiencies of these cells, being significantly higher in platinum-sensitive than in platinum-resistant patients and lowest in healthy volunteers (all P<0.05. We conclude

  13. Platinum coat color in red fox (Vulpes vulpes) is caused by a mutation in an autosomal copy of KIT.

    Science.gov (United States)

    Johnson, J L; Kozysa, A; Kharlamova, A V; Gulevich, R G; Perelman, P L; Fong, H W F; Vladimirova, A V; Oskina, I N; Trut, L N; Kukekova, A V

    2015-04-01

    The red fox (Vulpes vulpes) demonstrates a variety of coat colors including platinum, a common phenotype maintained in farm-bred fox populations. Foxes heterozygous for the platinum allele have a light silver coat and extensive white spotting, whereas homozygosity is embryonic lethal. Two KIT transcripts were identified in skin cDNA from platinum foxes. The long transcript was identical to the KIT transcript of silver foxes, whereas the short transcript, which lacks exon 17, was specific to platinum. The KIT gene has several copies in the fox genome: an autosomal copy on chromosome 2 and additional copies on the B chromosomes. To identify the platinum-specific KIT sequence, the genomes of one platinum and one silver fox were sequenced. A single nucleotide polymorphism (SNP) was identified at the first nucleotide of KIT intron 17 in the platinum fox. In platinum foxes, the A allele of the SNP disrupts the donor splice site and causes exon 17, which is part of a segment that encodes a conserved tyrosine kinase domain, to be skipped. Complete cosegregation of the A allele with the platinum phenotype was confirmed by linkage mapping (LOD 25.59). All genotyped farm-bred platinum foxes from Russia and the US were heterozygous for the SNP (A/G), whereas foxes with different coat colors were homozygous for the G allele. Identification of the platinum mutation suggests that other fox white-spotting phenotypes, which are allelic to platinum, would also be caused by mutations in the KIT gene. © 2015 Stichting International Foundation for Animal Genetics.

  14. Platinum clusters with precise numbers of atoms for preparative-scale catalysis.

    Science.gov (United States)

    Imaoka, Takane; Akanuma, Yuki; Haruta, Naoki; Tsuchiya, Shogo; Ishihara, Kentaro; Okayasu, Takeshi; Chun, Wang-Jae; Takahashi, Masaki; Yamamoto, Kimihisa

    2017-09-25

    Subnanometer noble metal clusters have enormous potential, mainly for catalytic applications. Because a difference of only one atom may cause significant changes in their reactivity, a preparation method with atomic-level precision is essential. Although such a precision with enough scalability has been achieved by gas-phase synthesis, large-scale preparation is still at the frontier, hampering practical applications. We now show the atom-precise and fully scalable synthesis of platinum clusters on a milligram scale from tiara-like platinum complexes with various ring numbers (n = 5-13). Low-temperature calcination of the complexes on a carbon support under hydrogen stream affords monodispersed platinum clusters, whose atomicity is equivalent to that of the precursor complex. One of the clusters (Pt 10 ) exhibits high catalytic activity in the hydrogenation of styrene compared to that of the other clusters. This method opens an avenue for the application of these clusters to preparative-scale catalysis.The catalytic activity of a noble metal nanocluster is tied to its atomicity. Here, the authors report an atom-precise, fully scalable synthesis of platinum clusters from molecular ring precursors, and show that a variation of only one atom can dramatically change a cluster's reactivity.

  15. Fluoropyrimidine and platinum toxicity pharmacogenetics: an umbrella review of systematic reviews and meta-analyses.

    Science.gov (United States)

    Campbell, Jared M; Bateman, Emma; Peters, Micah Dj; Bowen, Joanne M; Keefe, Dorothy M; Stephenson, Matthew D

    2016-03-01

    Fluoropyrimidine (FU) and platinum-based chemotherapies are greatly complicated by their associated toxicities. This umbrella systematic review synthesized all systematic reviews that investigated associations between germline variations and toxicity, with the aim of informing personalized medicine. Systematic reviews are important in pharmacogenetics where false positives are common. Four systematic reviews were identified for FU-induced toxicity and three for platinum. Polymorphisms of DPYD and TYMS, but not MTHFR, were statistically significantly associated with FU-induced toxicity (although only DPYD had clinical significance). For platinum, GSTP1 was found to not be associated with toxicity. This umbrella systematic review has synthesized the best available evidence on the pharmacogenetics of FU and platinum toxicity. It provides a useful reference for clinicians and identifies important research gaps.

  16. Exposure of the German general population to platinum and rhodium - Urinary levels and determining factors.

    Science.gov (United States)

    Munker, Sven; Kilo, Sonja; Röß, Christoph; Jeitner, Peter; Schierl, Rudolf; Göen, Thomas; Drexler, Hans

    2016-11-01

    In this study the exposure of the general population in Germany to platinum and rhodium and its determinants was investigated in 259 participants (subdivided in three groups) by urine analyses and assessment of the dental status. Complementary, an interview including questions characterising possible exposure to traffic exhaust was conducted. The median excretion was 2.42ng platinum/g creatinine and 7.27ng rhodium/g creatinine. The detailed analysis of the collected data showed significant higher platinum excretion values with increasing number of surfaces covered with restorations containing precious metals (R=0.389; prhodium excretion values (median=7.27ng/g; 95th percentile=13.5 ng/g). In summary, the study showed that exhaust emissions have an influence on platinum and rhodium excretion, but for platinum this influence is rather low compared to the influence of precious metals containing restorations. Copyright © 2016 Elsevier GmbH. All rights reserved.

  17. Electrical conductivity of platinum-implanted polymethylmethacrylate nanocomposite

    Science.gov (United States)

    Salvadori, M. C.; Teixeira, F. S.; Cattani, M.; Brown, I. G.

    2011-12-01

    Platinum/polymethylmethacrylate (Pt/PMMA) nanocomposite material was formed by low energy ion implantation of Pt into PMMA, and the transition from insulating to conducting phase was explored. In situ resistivity measurements were performed as the implantation proceeded, and transmission electron microscopy was used for direct visualization of Pt nanoparticles. Numerical simulation was carried out using the TRIDYN computer code to calculate the expected depth profiles of the implanted platinum. The maximum dose for which the Pt/PMMA system remains an insulator/conductor composite was found to be ϕ0 = 1.6 × 1016 cm-2, the percolation dose was 0.5 × 1016 cm-2, and the critical exponent was t = 1.46, indicating that the conductivity is due only to percolation. The results are compared with previously reported results for a Au/PMMA composite.

  18. Prediction of ligand effects in platinum-amyloid-β coordination.

    Science.gov (United States)

    Turner, Matthew; Deeth, Robert J; Platts, James A

    2017-08-01

    Ligand field molecular mechanics (LFMM) and semi-empirical Parametric Model 7 (PM7) methods are applied to a series of six Pt II -Ligand systems binding to the N-terminal domain of the amyloid-β (Aβ) peptide. Molecular dynamics using a combined LFMM/Assisted Model Building with Energy Refinement (AMBER) approach is used to explore the conformational freedom of the peptide fragment, and identifies favourable platinum binding modes and peptide conformations for each ligand investigated. Platinum coordination is found to depend on the nature of the ligand, providing evidence that binding mode may be controlled by suitable ligand design. Boltzmann populations at 310K indicate that each Pt-Aβ complex has a small number of thermodynamically accessible states. Ramachandran maps are constructed for the sampled Pt-Aβ conformations and secondary structural analysis of the obtained complex structures is performed and contrasted with the free peptide; coordination of these platinum complexes disrupts existing secondary structure in the Aβ peptide and promotes formation of ligand-specific turn-type secondary structure. Copyright © 2017 Elsevier Inc. All rights reserved.

  19. Clinical development of platinum complexes in cancer therapy: an historical perspective and an update.

    Science.gov (United States)

    Lebwohl, D; Canetta, R

    1998-09-01

    The vast amount of basic research on platinum coordination complexes has produced, over the past 25 years, several thousand new molecules for preclinical screening and 28 compounds which have entered clinical development. The goals of these research activities have been to identify compounds with superior efficacy, reduced toxicity, lack of cross-resistance or improved pharmacological characteristics as compared with the parent compound, cisplatin. After the remarkable therapeutic effects of cisplatin had been established, only a few other platinum compounds succeeded in reaching general availability. Whereas carboplatin is an analogue with an improved therapeutic index (mostly driven by reduced organ toxicity) over that of cisplatin, new compounds clearly more active than or non-cross-resistant with cisplatin have not yet been identified. The platinum analogues that remain under investigation are focusing on expanding the utilisation of platinum therapy to tumour types not usually treated with, or responsive to, cisplatin or carboplatin. In addition, novel routes of administration constitute another avenue of research. The clinical development of platinum coordination complexes, with emphasis on those compounds still under active development, is reviewed.

  20. The stability of PEMFC electrodes : platinum dissolution vs potential and temperature investigated by quartz crystal microbalance

    NARCIS (Netherlands)

    Dam, V.A.T.; Bruijn, de F.A.

    2007-01-01

    The stability of platinum in proton exchange membrane fuel cell (PEMFC) electrodes has been investigated by determining the dissolution of platinum from a thin platinum film deposited on a gold substrate in 1 M HClO4 at different temperatures ranging between 40 and 80°C and potentials between 0.85

  1. Photoreactivation of ultraviolet light-induced damage in cultured fish cells as revealed by increased colony forming ability and decreased content of pyrimidine dimers

    International Nuclear Information System (INIS)

    Shima, A.; Ikenaga, M.; Egami, N.

    1981-01-01

    Cultured cells derived from a goldfish were irradiated with 254 nm ultraviolet light. Cell survival and splitting of pyrimidine dimers after photoreactivation treatment with white fluorescent lamps were examined by colony forming ability and by a direct dimer assay, respectively. When UV-irradiated (5 J/m 2 ) cells were illuminated by photoreactivating light, cell survival was enhanced up to a factor of 9(40 min) followed by a decline after prolonged exposures. Exposure of UV-irradiated (15 J/m 2 ) cells to radiation from white fluorescent lamps reduced the amounts of thymine-containing dimers in a photoreactivating fluence dependent manner, up to about 60% reduction at 120 min exposure. Keeping UV-irradiated cells in the dark for up to 120 min did not affect either cell survival or the amount of pyrimidine dimers in DNA, indicating that there were not detectable levels of a dark-repair system in the cells under our conditions. Correlation between photoreactivation of colony forming ability and photoreactivation of the pyrimidine dimers was demonstrated, at least at relatively low fluences of photoreactivating light. (author)

  2. Photoreactivation of ultraviolet light-induced damage in cultured fish cells as revealed by increased colony forming ability and decreased content of pyrimidine dimers

    Energy Technology Data Exchange (ETDEWEB)

    Shima, A. (Shiga University of Medical Science, Otsu (Japan)); Ikenaga, M. (Osaka Univ. (Japan). Faculty of Medicine); Nikaido, O.; Takebe, H. (Kyoto Univ. (Japan)); Egami, N. (Tokyo Univ. (Japan). Faculty of Science)

    1981-03-01

    Cultured cells derived from a goldfish were irradiated with 254 nm ultraviolet light. Cell survival and splitting of pyrimidine dimers after photoreactivation treatment with white fluorescent lamps were examined by colony forming ability and by a direct dimer assay, respectively. When UV-irradiated (5 J/m/sup 2/) cells were illuminated by photoreactivating light, cell survival was enhanced up to a factor of 9(40 min) followed by a decline after prolonged exposures. Exposure of UV-irradiated (15 J/m/sup 2/) cells to radiation from white fluorescent lamps reduced the amounts of thymine-containing dimers in a photoreactivating fluence dependent manner, up to about 60% reduction at 120 min exposure. Keeping UV-irradiated cells in the dark for up to 120 min did not affect either cell survival or the amount of pyrimidine dimers in DNA, indicating that there were not detectable levels of a dark-repair system in the cells under our conditions. Correlation between photoreactivation of colony forming ability and photoreactivation of the pyrimidine dimers was demonstrated, at least at relatively low fluences of photoreactivating light.

  3. Involvement of UV-inducible repair in pyrimidine dimer excision in Escherichia coli

    International Nuclear Information System (INIS)

    Masek, F.; Sedliakova, M.

    1978-01-01

    The influence of UV radiation on pyrimidine dimer excision in the cells of three excision-proficient E.coli strains was studied. For this purpose cells were irradiated with a first fluence of 300 ergs/mm 2 and at different time intervals with a second fluence of 500 ergs/mm 2 . After the second fluence dimer excision was found to be partly inhibited in E.coli B/r Hcr + and E.coli 15 555-7, but not in E.coli K12 SR20. (author)

  4. Crystal structure of 4-allylsulfanyl-1H-pyrazolo[3,4-d]pyrimidine

    Directory of Open Access Journals (Sweden)

    Mohammed El Fal

    2014-09-01

    Full Text Available In the title compound, C8H8N4S, the pyrazolo[3,4-d]pyrimidine ring system is essentially planar, with a maximum deviation from the mean plane of 0.025 (3 Å. The allyl group is disordered over two sites in a 0.512 (6:0.488 (6 ratio. In the crystal, molecules are linked by pairs of N—H...N hydrogen bonds, forming inversion dimers with an R22(8 graph-set motif.

  5. Involvement of UV-inducible repair in pyrimidine dimer excision in Escherichia coli

    Energy Technology Data Exchange (ETDEWEB)

    Masek, F; Sedliakova, M [Slovenska Akademia Vied, Bratislava (Czechoslovakia)

    1978-11-15

    The influence of UV radiation on pyrimidine dimer excision in the cells of three excision-proficient E.coli strains was studied. For this purpose cells were irradiated with a first fluence of 300 ergs/mm/sup 2/ and at different time intervals with a second fluence of 500 ergs/mm/sup 2/. After the second fluence dimer excision was found to be partly inhibited in E.coli B/r Hcr/sup +/ and E.coli 15 555-7, but not in E.coli K12 SR20.

  6. Platinum(II) complexes as spectroscopic probes for biomolecules

    Energy Technology Data Exchange (ETDEWEB)

    Ratilla, E.

    1990-09-21

    The use of platinum(II) complexes as tags and probes for biomolecules is indeed advantageous for their reactivities can be selective for certain purposes through an interplay of mild reaction conditions and of the ligands bound to the platinum. The use of {sup 195}Pt NMR as a method of detecting platinum and its interactions with biomolecules was carried out with the simplest model of platinum(II) tagging to proteins. Variable-temperature {sup 195}Pt NMR spectroscopy proved useful in studying the stereodynamics of complex thioethers like methionine. The complex, Pt(trpy)Cl{sup +}, with its chromophore has a greater potential for probing proteins. It is a noninvasive and selective tag for histidine and cysteine residues on the surface of cytochrome c at pH 5. The protein derivatives obtained are separable, and the tags are easily quantitated and differentiated through the metal-to-ligand charge transfer bands which are sensitive to the environment of the tag. Increasing the pH to 7.0 led to the modification by Pt(trpy)Cl{sup +}of Arg 91 in cytochrome c. Further studies with guanidine-containing ligands as models for arginine modification by Pt(trpy)Cl{sup +} showed that guanidine can act as a terminal ligand and as a bridging ligand. Owing to the potential utility of Pt(trpy)L{sup n+} as electron dense probes of nucleic acid structure, interactions of this bis-Pt(trpy){sup 2+} complex with nucleic acids was evaluated. Indeed, the complex interacts non-covalently with nucleic acids. Its interactions with DNA are not exactly the same as those of its precedents. Most striking is its ability to form highly immobile bands of DNA upon gel electrophoresis. 232 refs.

  7. Responses of fibroblasts and glial cells to nanostructured platinum surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Pennisi, C P; Sevcencu, C; Yoshida, K [Center for Sensory-Motor Interaction (SMI), Aalborg University, Aalborg (Denmark); Dolatshahi-Pirouz, A; Foss, M; Larsen, A Nylandsted; Besenbacher, F [Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus (Denmark); Hansen, J Lundsgaard [Department of Physics and Astronomy, Aarhus University, Aarhus (Denmark); Zachar, V, E-mail: cpennisi@hst.aau.d [Laboratory for Stem Cell Research, Aalborg University (Denmark)

    2009-09-23

    The chronic performance of implantable neural prostheses is affected by the growth of encapsulation tissue onto the stimulation electrodes. Encapsulation is associated with activation of connective tissue cells at the electrode's metallic contacts, usually made of platinum. Since surface nanotopography can modulate the cellular responses to materials, the aim of the present work was to evaluate the 'in vitro' responses of connective tissue cells to platinum strictly by modulating its surface nanoroughness. Using molecular beam epitaxy combined with sputtering, we produced platinum nanostructured substrates consisting of irregularly distributed nanopyramids and investigated their effect on the proliferation, cytoskeletal organization and cellular morphology of primary fibroblasts and transformed glial cells. Cells were cultured on these substrates and their responses to surface roughness were studied. After one day in culture, the fibroblasts were more elongated and their cytoskeleton less mature when cultured on rough substrates. This effect increased as the roughness of the surface increased and was associated with reduced cell proliferation throughout the observation period (4 days). Morphological changes also occurred in glial cells, but they were triggered by a different roughness scale and did not affect cellular proliferation. In conclusion, surface nanotopography modulates the responses of fibroblasts and glial cells to platinum, which may be an important factor in optimizing the tissue response to implanted neural electrodes.

  8. Production of platinum radioisotopes at Brookhaven Linac Isotope Producer (BLIP

    Directory of Open Access Journals (Sweden)

    Smith Suzanne V.

    2017-01-01

    Full Text Available The accelerator production of platinum isotopes was investigated at the Brookhaven Linac Isotope Producer (BLIP. In this study high purity natural platinum foils were irradiated at 53.2, 65.7, 105.2, 151.9, 162.9 and 173.3.MeV. The irradiated foils were digested in aqua regia and then converted to their hydrochloride salt with concentrated hydrochloric acid before analyzing by gamma spectrometry periodically for at least 10 days post end of bombardment. A wide range of platinum (Pt, gold (Au and iridium (Ir isotopes were identified. Effective cross sections at BLIP for Pt-188, Pt-189, Pt-191 and Pt-195m were compared to literature and theoretical cross sections determined using Empire-3.2. The majority of the effective cross sections (<70 MeV confirm those reported in the literature. While the absolute values of the theoretical cross sections were up to a factor of 3 lower, Empire 3.2 modeled thresholds and maxima correlated well with experimental values. Preliminary evaluation into a rapid separation of Pt isotopes from high levels of Ir and Au isotopes proved to be a promising approach for large scale production. In conclusion, this study demonstrated that with the use of isotopically enriched target material accelerator production of selected platinum isotopes is feasible over a wide proton energy range.

  9. Metal Oxide-Supported Platinum Overlayers as Proton-Exchange Membrane Fuel Cell Cathodes

    DEFF Research Database (Denmark)

    Tripkovic, Vladimir; Abild-Pedersen, Frank; Studt, Felix

    2012-01-01

    We investigated the activity and stability of n=(1, 2, 3) platinum layers supported on a number of rutile metal oxides (MO2; M=Ti, Sn, Ta, Nb, Hf and Zr). A suitable oxide support can alleviate the problem of carbon corrosion and platinum dissolution in Pt/C catalysts. Moreover, it can increase t...

  10. On the mobility of carbon-supported platinum nanoparticles towards unveiling cathode degradation in water electrolysis

    Science.gov (United States)

    Paciok, Paul; Schalenbach, Maximilian; Carmo, Marcelo; Stolten, Detlef

    2017-10-01

    This study investigates the influence of the hydrogen evolution reaction (HER) overpotential on the mobility of carbon-supported platinum particles. The migration of the platinum over the carbon support was analyzed by means of identical location transmission electron microscopy (IL-TEM). While at potentials of 0.1 and 0 V vs. reversible hydrogen electrode (RHE), no changes to the Pt/C material were observed. With a decrease of the overpotential to -0.1 V vs. RHE, an increase in the quantity of migrating platinum particles took place. At -0.2 V vs. RHE, a further rise in the particle migration was observed. The effect of the overpotential on the migration was explained by a higher hydrogen generation rate, the formation of a hydrogen monolayer on the platinum and the resulting changes of the platinum support distance. The mechanisms revealed in this study could describe a relevant source of degradation of PEM water electrolyzers.

  11. A phenyl-sulfonic acid anchored carbon-supported platinum catalyst for polymer electrolyte fuel cell electrodes

    International Nuclear Information System (INIS)

    Selvarani, G.; Sahu, A.K.; Choudhury, N.A.; Sridhar, P.; Pitchumani, S.; Shukla, A.K.

    2007-01-01

    A method, to anchor phenyl-sulfonic acid functional groups with the platinum catalyst supported onto a high surface-area carbon substrate, is reported. The use of the catalyst in the electrodes of a polymer electrolyte fuel cell (PEFC) helps enhancing its performance. Characterization of the catalyst by Fourier transform infra red (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS) and point-of-zero-charge (PZC) studies suggests that the improvement in performance of the PEFC is facilitated not only by enlarging the three-phase boundary in the catalyst layer but also by providing ionic-conduction paths as well as by imparting negative charge to platinum sites with concomitant oxidation of sulfur present in the carbon support. It is argued that the negatively charged platinum sites help repel water facilitating oxygen to access the catalyst sites. The PEFC with modified carbon-supported platinum catalyst electrodes exhibits 40% enhancement in its power density as compared to the one with unmodified carbon-supported platinum catalyst electrodes

  12. How study patients who receive fluo pyrimidines to prevent ischemic events; Como estudiar los pacientes que recibiran fluopirimidinas para prevenir eventos isquemicos

    Energy Technology Data Exchange (ETDEWEB)

    Saldombide, L. [Hospital de Clinicas. Montevideo (Uruguay)

    2010-11-15

    Introduction: Ischemic heart disease is the main cause of death in Uruguay and cancer is the second. The pillar of the systemic treatment of colorectal cancer are fluo pyrimidines and cause acute ischemic events in 3-8% of t rated patients. The 5 fluorouracil is the third anticancer drug most used Objective: Due to the high incidence of the two diseases and the risk of death caused by the ischemic treatment complications, the literature is analyzed to define how to study patients who receive fluo pyrimidines as a medium of preventing the same. Development: fluo pyrimidines cardio-toxicity can occur by myocardial toxicity, vasospasm, dihydropyrimidine dehydrogenase deficiency, autoimmune phenomena, platelet hyper aggregability, etc. The clinic is varied and underestimated: angina, abnormal ST silent and reversible, arrhythmias, heart failure, hypertension and heart failure. It is the most common complication with continuous infusion of 5 Fu and its equivalent capecitabine with bolus f lou pyrimidines. It is common that ischemic heart disease prioritises the risk increase of complications, but their absence does not exist. Without ischemic heart disease it is difficult to prevent ischemic events, however proposes that the older higher risk. Results: No uniform guidelines is advised: detailed history, determine if risk factors such as smoking, hypertension, diabetes and dyslipidemia and They are present electrocardiogram and cardiac evaluation. Warn the patient about angina l pain as early symptom and monitor symptoms during chemotherapy including cardio-vascular hypotension. Discontinue the medication and perform classic anti-angina l symptoms and / or signs of ischemia. Not reintroduce unless it is the only therapeutic option, since mortality may exceed.

  13. Investigation of mechanical and structural characteristics of platinum and palladium at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Trumie, B. T.; Gomidzelovie, L.; Marjanovic, S. R.; Krstic, V. R.

    2015-03-30

    In order to broaden future application of products based on platinum and palladium a comparative analysis of their high-temperature mechanical properties was performed. Platinum and palladium are of great importance and are widely used in chemical industry, electronics, for making laboratory dishes, to name a few. Mechanical properties of pure metals, such as: tensile strength, creep rate and rupture time were investigated using universal testing machine for tensile testing of materials. Microstructure of samples was investigated by optical microscopy. Based on obtained results it can be concluded that the platinum, compared to palladium, is superior for high-temperature applications. (Author)

  14. Investigation of mechanical and structural characteristics of platinum and palladium at high temperatures

    International Nuclear Information System (INIS)

    Trumie, B. T.; Gomidzelovie, L.; Marjanovic, S. R.; Krstic, V. R.

    2015-01-01

    In order to broaden future application of products based on platinum and palladium a comparative analysis of their high-temperature mechanical properties was performed. Platinum and palladium are of great importance and are widely used in chemical industry, electronics, for making laboratory dishes, to name a few. Mechanical properties of pure metals, such as: tensile strength, creep rate and rupture time were investigated using universal testing machine for tensile testing of materials. Microstructure of samples was investigated by optical microscopy. Based on obtained results it can be concluded that the platinum, compared to palladium, is superior for high-temperature applications. (Author)

  15. Synthesis, Antibacterial and Antitubercular Activities of Some 5H-Thiazolo[3,2-a]pyrimidin-5-ones and Sulfonic Acid Derivatives

    Directory of Open Access Journals (Sweden)

    Dong Cai

    2015-09-01

    Full Text Available A series of 5H-thiazolo[3,2-a]pyrimidin-5-ones were synthesized by the cyclization reactions of S-alkylated derivatives in concentrated H2SO4. Upon treatment of S-alkylated derivatives at different temperatures, intramolecular cyclization to 7-(substituted phenylamino-5H-thiazolo[3,2-a]pyrimidin-5-ones or sulfonation of cyclized products to sulfonic acid derivatives occurred. The structures of the target compounds were confirmed by IR, 1H-NMR, 13C-NMR and HRMS studies. The compounds were evaluated for their preliminary in vitro antibacterial activity against some Gram-positive and Gram-negative bacteria and screened for antitubercular activity against Mycobacterium tuberculosis by the broth dilution assay method. Some compounds showed good antibacterial and antitubercular activities.

  16. Solid supported microwave induced synthesis of imidazole–pyrimidine hybrids: Antimicrobial evaluation and docking study as 14DM-CPY51 inhibitors

    Directory of Open Access Journals (Sweden)

    Naziyanaz B. Pathan

    2016-09-01

    Full Text Available As part of our exploration for new antifungal agents, substituted 4,5-diphenyl imidazolyl pyrimidine hybrids were synthesized. A series of substituted ethyl 1,2,3,6-tetrahydro-4-methyl-2-oxo/thioxo-6-phenyl-1-(4,5-diphenyl-1-H-imidazol-2-yl pyrimidine-5-carboxylates have been studied for their binding active sites of cytochrome P450 14α-sterol demethylase CPY51 enzyme. For comparison, the binding behavior of known 14DM selective (Fluconazole and non-selective (Clotrimazole, Miconazole, Griesofulvin drugs has also been studied. Synthesized compounds were screened for their in vitro antibacterial activity against Staphylococcus aureus, Salmonella typhi, Pseudomonas aurogenosa and Klebsiella pneumonae and also antifungal activity against the opportunistic pathogens Candida albicans.

  17. Speciation of platinum(IV) in nitric acid solutions.

    Science.gov (United States)

    Vasilchenko, Danila; Tkachev, Sergey; Baidina, Iraida; Korenev, Sergey

    2013-09-16

    The speciation of platinum(IV) ions in nitric acid (6-15.8 M) solutions of H2[Pt(OH)6] has been studied by (195)Pt NMR and Raman spectroscopy. Series of aqua-hydroxo-nitrato complexes [Pt(L)(x)(NO3)(6-x)] (L = H2O or OH(-); x = 0, ..., 6) were found to exist in such solutions. The pair additivity model of chemical shifts and statistical theory were used to assign signals in NMR spectra to particular [Pt(L)(x)(NO3)(6-x)] species. Mononuclear hexanitratoplatinates(IV) have been isolated in solid state in substantial yield as pyridinium salt (PyH)2[Pt(NO3)6] and characterized by single-crystal X-ray diffraction. Aging of the platinum nitric acid solutions for more than 5-6 h results in oligomerization of [Pt(L)(x)(NO3)(6-x)] species and the formation of oligonuclear aqua-hydroxo-nitrato complexes with OH(-) and NO3(-) bridging ligands. Oligomeric platinum(IV) complexes with two and four nuclei were unambiguously detected by NMR on (195)Pt -enriched samples. Oligomers with even higher nuclearity were also detected. Dimeric anions [Pt2(μ-OH)2(NO3)8](2-) have been isolated as single crystals of tetramethylammonium salt and characterized by X-ray diffraction.

  18. ESR study of radiation damage in pyrimidines. Progress report, August 1, 1975--April 1, 1976

    International Nuclear Information System (INIS)

    Benson, B.W.

    1976-04-01

    The primary objective of this project is to develop general mechanisms for radiation damage to biomolecules using substituted pyrimidines as a model system. Results this year include a single crystal ESR study of 5-ethyl-5-isopropylbarbituric acid, development of the k-band microwave bridge, dose response measurements on methylated barbituric acid derivatives, and synthesis of several specifically deuterated uracil derivatives

  19. Platinum redispersion on metal oxides in low temperature fuel cells.

    Science.gov (United States)

    Tripković, Vladimir; Cerri, Isotta; Nagami, Tetsuo; Bligaard, Thomas; Rossmeisl, Jan

    2013-03-07

    We have analyzed the aptitude of several metal oxide supports (TiO(2), SnO(2), NbO(2), ZrO(2), SiO(2), Ta(2)O(5) and Nb(2)O(5)) to redisperse platinum under electrochemical conditions pertinent to the Proton Exchange Membrane Fuel Cell (PEMFC) cathode. The redispersion on oxide supports in air has been studied in detail; however, due to different operating conditions it is not straightforward to link the chemical and the electrochemical environment. The largest differences reflect in (1) the oxidation state of the surface (the oxygen species coverage), (2) temperature and (3) the possibility of platinum dissolution at high potentials and the interference of redispersion with normal working potential of the PEMFC cathode. We have calculated the PtO(x) (x = 0, 1, 2) adsorption energies on different metal oxides' surface terminations as well as inside the metal oxides' bulk, and we have concluded that NbO(2) might be a good support for platinum redispersion at PEMFC cathodes.

  20. Protection against the clastogenic effect of CIS-PLATINUM by WR-2721, ATP and Vitamin C

    International Nuclear Information System (INIS)

    Rupova, I.; Yagova, A.

    1993-01-01

    The mutagenic effect of antineoplastic drug Cis-Platinum has been assessed by the frequency of micronuclei in polychromatic erythrocytes (PE) in the mouse bone marrow at time intervals of 24, 48 and 73 h. The maximal clastogenic effect of 2 mg/kg of Cis-Platinum has been found at 24 h interval after treatment (3.6%). The protection against mutagenic activity of Cis-Platinum has been studied by pretreatment of the mice with the thiophosphate compound WR-2721, adenosine triphosphate (ATP) and Vitamin C alone or in combinations at the time of maximal response. The radioprotector WR-2721 exerts a high anti-mutagenic activity when applied prior to Cis-Platinum (2.2%; p 0.05). (author)

  1. An Efficient and Facile Methodology for Bromination of Pyrimidine and Purine Nucleosides with Sodium Monobromoisocyanurate (SMBI

    Directory of Open Access Journals (Sweden)

    Roger Stromberg

    2013-10-01

    Full Text Available An efficient and facile strategy has been developed for bromination of nucleosides using sodium monobromoisocyanurate (SMBI. Our methodology demonstrates bromination at the C-5 position of pyrimidine nucleosides and the C-8 position of purine nucleosides. Unprotected and also several protected nucleosides were brominated in moderate to high yields following this procedure.

  2. Consortium analysis of gene and gene–folate interactions in purine and pyrimidine metabolism pathways with ovarian carcinoma risk

    DEFF Research Database (Denmark)

    Kelemen, Linda E; Terry, Kathryn L; Goodman, Marc T

    2014-01-01

    SCOPE: We reevaluated previously reported associations between variants in pathways of one-carbon (1-C) (folate) transfer genes and ovarian carcinoma (OC) risk, and in related pathways of purine and pyrimidine metabolism, and assessed interactions with folate intake. METHODS AND RESULTS: Odds rat...

  3. Modification of potentially lethal damage in irradiated Chinese hamster V79 cells after incorporation of halogenated pyrimidines

    NARCIS (Netherlands)

    Franken, N. A.; van Bree, C. V.; Kipp, J. B.; Barendsen, G. W.

    1997-01-01

    Radiosensitization of exponentially growing and plateau phase Chinese hamster V79 cells by incorporation of halogenated pyrimidines (HP) was investigated for different culture conditions that influenced repair. For this purpose cells were grown for 72 h with 0, 1, 2 and 4 microM of chloro-(CldUrd),

  4. Studies on Synthesis of Some Novel Heterocyclic Chalcone, Pyrazoline, Pyrimidine - 2 - One, Pyrimidine - 2 - Thione, para-Acetanilide Sulphonyl and Benzoyl Derivatives and their Antimicrobial Activity

    Directory of Open Access Journals (Sweden)

    Rakesh N. Mistry

    2005-01-01

    Full Text Available 1, 2 - Dichloro benzene on chlorosulphonation by chlorosulphonic acid gives 1, 2 - [dichloro] - benzene sulphonyl chloride which on condensation with p –amino acetophenone gives 1-[acetyl] - 1’ , 2’ - [dichloro] - dibenz sulphonamide derivative. This derivative undergo condensation with 2,4- dichloro benzaldehyde gives 1- [3” - (sub. phenyl - 2” - propene - 1” - one] - 1’ , 2’ - [dichloro] - dibenz sulphonamide derivative which on reaction with 99% hydrazine hydrate and glacial acetic acid gives 1-[acetyl]-3- [1’ , 2’ - (dichloro - dibenz sulphonamide] -5 - [2” , 4” - dichloro phenyl] - 2 - pyrazoline derivative. This derivative reacts with various substituted aldehydes to give corresponding substituted chalcone derivatives [1(a-j]. Now, these chalcone derivatives [1(a-j] on condensation with urea gives corresponding substituted pyrimidine - 2 - one derivatives [2(a-j] and on condensation with thio-urea gives corresponding substituted pyrimidine- 2 -thione derivatives [3(a-j]. Further, these chalcone derivatives [1(a-j] on reaction with 99% hydrazine hydrate gives 1 - [1’ - (H - 5’ - (sub. phenyl - 2’ - pyrazoline]- 3 - [1” , 2” - (dichloro - dibenz sulphonamide] - 5 - [2’’’ , 4’’’ - dichloro phenyl]-2- pyrazoline derivatives [4(a-j] as an intermediate compounds, which on condensation with p-acetanilide sulphonyl chloride gives corresponding substituted p - acetanilide sulphonyl derivatives [5(a-j] and on condensation with benzoyl chloride gives corresponding substituted benzoyl derivatives [6(a-j]. Structure elucidation of synthesised compounds has been made on the basis of elemental analysis, I.R. spectral studies and 1H N.M.R. spectral studies. The antimicrobial activity of the synthesised compounds has been studied against the cultures “Staphylococcus aureus”, “Escherichia coli” and “Candela albicans”.

  5. Design, Synthesis, and Herbicidal Activity of Pyrimidine-Biphenyl Hybrids as Novel Acetohydroxyacid Synthase Inhibitors.

    Science.gov (United States)

    Li, Ke-Jian; Qu, Ren-Yu; Liu, Yu-Chao; Yang, Jing-Fang; Devendar, Ponnam; Chen, Qiong; Niu, Cong-Wei; Xi, Zhen; Yang, Guang-Fu

    2018-04-18

    The issue of weed resistance to acetohydroxyacid synthase (EC 2.2.1.6, AHAS) inhibitors has become one of the largest obstacles for the application of this class of herbicides. In a continuing effort to discover novel AHAS inhibitors to overcome weed resistance, a series of pyrimidine-biphenyl hybrids (4aa-bb and 5aa-ah) were designed and synthesized via a scaffold hopping strategy. Among these derivatives, compounds 4aa ( K i = 0.09 μM) and 4bb ( K i = 0.02 μM) displayed higher inhibitory activities against Arabidopsis thaliana AHAS than those of the controls bispyribac ( K i = 0.54 μM) and flumetsulam ( K i = 0.38 μM). Remarkably, compounds 4aa, 4bb, 5ah, and 5ag exhibited excellent postemergence herbicidal activity and a broad spectrum of weed control at application rates of 37.5-150 g of active ingredient (ai)/ha. Furthermore, 4aa and 4bb showed higher herbicidal activity against AHAS inhibitor-resistant Descurainia sophia, Ammannia arenaria, and the corresponding sensitive weeds than that of bispyribac at 0.94-0.235 g ai/ha. Therefore, the pyrimidine-biphenyl motif and lead compounds 4aa and 4bb have great potential for the discovery of novel AHAS inhibitors to combat AHAS-inhibiting herbicide-resistant weeds.

  6. Green Transformational Leadership and Green Performance: The Mediation Effects of Green Mindfulness and Green Self-Efficacy

    Directory of Open Access Journals (Sweden)

    Yu-Shan Chen

    2014-09-01

    Full Text Available No prior literature explores the influence of green transformational leadership on green performance, thus, this study develops a novel research framework to fill the research gap. This study investigates the influence of green transformational leadership on green performance and discusses the mediation effects of green mindfulness and green self-efficacy by means of structural equation modeling (SEM. The results indicate that green transformational leadership positively influences green mindfulness, green self-efficacy, and green performance. Moreover, this study demonstrates that the positive relationship between green transformational leadership and green performance is partially mediated by the two mediators: green mindfulness and green self-efficacy. It means that green transformational leadership can not only directly affect green performance positively but also indirectly affect it positively through green mindfulness and green self-efficacy. Therefore, firms need to raise their green transformational leadership, green mindfulness, and green self-efficacy to increase their green performance.

  7. SEROTONIN METABOLISM FOLLOWING PLATINUM-BASED CHEMOTHERAPY COMBINED WITH THE SEROTONIN TYPE-3 ANTAGONIST TROPISETRON

    NARCIS (Netherlands)

    SCHRODER, CP; VANDERGRAAF, WTA; KEMA, IP; GROENEWEGEN, A; SLEIJFER, DT; DEVRIES, EGE

    1995-01-01

    The administration of platinum-based chemotherapy induces serotonin release from the enterochromaffin cells, causing nausea and vomiting. This study was conducted to evaluate parameters of serotonin metabolism following platinum-based chemotherapy given in combination with the serotonin type-3

  8. Acyclic nucleoside bisphosphonates: Synthesis and properties of chiral 2-amino-4,6-bis[(phosphonomethoxy)alkoxy]pyrimidines

    Czech Academy of Sciences Publication Activity Database

    Doláková, Petra; Dračínský, Martin; Masojídková, Milena; Šolínová, Veronika; Kašička, Václav; Holý, Antonín

    2009-01-01

    Roč. 44, č. 6 (2009), s. 2408-2424 ISSN 0223-5234 R&D Projects: GA MŠk 1M0508 Grant - others:NIH(US) 1UC1AIO62540-01 Institutional research plan: CEZ:AV0Z40550506 Keywords : acyclic nucleoside phosphonates * pyrimidine * bisphosphonates Subject RIV: CC - Organic Chemistry Impact factor: 3.269, year: 2009

  9. A Single Platinum Microelectrode for Identifying Soft Drink Samples

    Directory of Open Access Journals (Sweden)

    Lígia Bueno

    2012-01-01

    Full Text Available Cyclic voltammograms recorded with a single platinum microelectrode were used along with a non-supervised pattern recognition, namely, Principal Component Analysis, to conduct a qualitative analysis of sixteen different brands of carbonated soft drinks (Kuat, Soda Antarctica, H2OH!, Sprite 2.0, Guarana Antarctica, Guarana Antarctica Zero, Coca-Cola, Coca-Cola Zero, Coca-Cola Plus, Pepsi, Pepsi Light, Pepsi Twist, Pepsi Twist Light, Pepsi Twist 3, Schin Cola, and Classic Dillar’s. In this analysis, soft drink samples were not subjected to pre-treatment. Good differentiation among all the analysed soft drinks was achieved using the voltammetric data. An analysis of the loading plots shows that the potentials of −0.65 V, −0.4 V, 0.4 V, and 0.750 V facilitated the discrimination process. The electrochemical processes related to this potential are the reduction of hydrogen ions and inhibition of the platinum oxidation by the caffeine adsorption on the electrode surface. Additionally, the single platinum microelectrode was useful for the quality control of the soft drink samples, as it helped to identify the time at which the beverage was opened.

  10. Synthesis and structure-activity relationship studies of polysubstituted pyrimidines as inhibitors of immune-activated nitric oxide production

    Czech Academy of Sciences Publication Activity Database

    Jansa, Petr; Holý, Antonín; Dračínský, Martin; Kolman, Viktor; Janeba, Zlatko; Kmoníčková, Eva; Zídek, Zdeněk

    2015-01-01

    Roč. 24, č. 5 (2015), s. 2154-2166 ISSN 1054-2523 R&D Projects: GA ČR(CZ) GAP303/12/0172; GA MV VG20102015046 Institutional support: RVO:61388963 ; RVO:68378041 Keywords : pyrimidine * nitric oxide * NO * anti-inflammatory Subject RIV: CC - Organic Chemistry Impact factor: 1.436, year: 2015

  11. Comparison of different sample preparation methods for platinum determination in cultured cells by graphite furnace atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    Man Xiao

    2017-01-01

    Full Text Available Background Platinum-based agents are widely used in chemotherapy against solid tumors and insufficient intracellular drug accumulation is one of the leading causes of platinum resistance which is associated with poor survival of tumor patients. Thus, the detection of intracellular platinum is pivotal for studies aiming to overcome platinum resistance. In the present study, we aimed to establish a reliable graphite furnace atomic absorption spectrometry (GFAAS-based assay to quantify the intracellular platinum content for cultured cells. Methods Several most commonly applied cell preparation methods, including 0.2% HNO3, 0.2% Triton X-100, concentrated nitric acid, RIPA combined with concentrated nitric acid and hydroxide, followed by GFAAS for platinum detection were compared in ovarian, cervical and liver cancer cell lines to obtain the optimal one, and parameters regarding linearity, accuracy, precision and sensitivity were evaluated. Influence of other metals on platinum detection and the storage conditions of samples were also determined. Results The treatment of cells with 0.2% HNO3 was superior to other approaches with fewer platinum loss and better repeatability. The recovery rate and precision of this method were 97.3%–103.0% and 1.4%–3.8%, respectively. The average recoveries in the presence of other metals were 95.1%–103.1%. The detection limit was 13.23 ug/L. The recovery rate of platinum remained acceptable even in cell samples stored in −20 °C or −80 °C for two months. Discussion After comparison, we found that 0.2% HNO3 was optimal for intracellular platinum quantification based on GFAAS, which presented values compatible with that of inductively-coupled plasma mass-spectrometry (ICP-MS, and this is partially attributed to the simplicity of this method. Moreover, the assay was proved to be accurate, sensitive, cost-effective and suitable for the research of platinum-based antitumor therapy.

  12. Crystal structure of 1-methyl-4-methylsulfanyl-1H-pyrazolo[3,4-d]pyrimidine

    Directory of Open Access Journals (Sweden)

    Mohammed El Fal

    2014-12-01

    Full Text Available In the title compound, C7H8N4S, the non-H atoms of the pyrazolo[3,4-d]pyrimidine ring system and the methylsulfanyl group lie on a crystallographic mirror plane. In the crystal, molecules are linked via a number of π–π interactions [centroid–centroid distances vary from 3.452 (7 to 3.6062 (8 Å], forming a three-dimensional structure.

  13. Oxygen-related 1-platinum defects in silicon: An electron paramagnetic resonance study

    Science.gov (United States)

    Juda, U.; Scheerer, O.; Höhne, M.; Riemann, H.; Schilling, H.-J.; Donecker, J.; Gerhardt, A.

    1996-09-01

    A monoclinic 1-platinum defect recently detected was investigated more thoroughly by electron paramagnetic resonance (EPR). The defect is one of the dominating defects in platinum doped silicon. With a perfect reproducibility it is observed in samples prepared from n-type silicon as well as from p-type silicon, in float zone (FZ) silicon as well as in Czochralski (Cz) silicon. Its concentration varies with the conditions of preparation and nearly reaches that of isolated substitutional platinum in Cz silicon annealed for 2 h at 540 °C after quenching from the temperature of platinum diffusion. Because of its concentration which in Cz-Si exceeds that in FZ-Si the defect is assumed to be oxygen-related though a hyperfine structure with 17O could not be resolved. The defect causes a level close to the valence band. This is concluded from variations of the Fermi level and from a discussion of the spin Hamiltonian parameters. In photo-EPR experiments the defect is coupled to recently detected acceptorlike self-interstitial related defects (SIRDs); their level position turns out to be near-midgap. These defects belong to the lifetime limiting defects in Pt-doped Si.

  14. Prophage induction and mutagenicity of a series of anti-tumour platinum(II) and platinum(IV) co-ordination complexes

    NARCIS (Netherlands)

    Mattern, I.E.; Cocchiarella, L.; Kralingen, C.G. van; Lohman, P.H.M.

    1982-01-01

    Eleven platinum compounds with nitrogen donor ligands, previously tested for anti-tumour activity were studied for induction of prophage lambda and for mutagenicity in the Ames assay, with various strains of Salmonella. The compounds included cis and trans isomers of Pt(II) and Pt(IV) complexes and

  15. Platinum-group element mineralization

    International Nuclear Information System (INIS)

    Gruenewaldt, G.

    1985-01-01

    The purpose of this investigation is to determine the geological processes responsible for the abnormal enrichment of the platinum-group elements (PGE) in the mineralized layers of the Bushveld Complex. Questions asked are: what processes caused enrichment of the Bushveld magma in the PGE ; by what processes were these PGE concentrated in the mineralized layers ; was contamination of the Bushveld magma from external sources important in the formation of the PGE enriched layers ; what are the effects of fractional crystallization on the PGE ratios

  16. Rockburst damage mechanism at Impala Platinum Mine

    CSIR Research Space (South Africa)

    Ledwaba, LS

    2012-05-01

    Full Text Available Impala Platinum Mine (Impala), situated north of the town of Rustenburg in the North West Province of South Africa, has experienced an increase in seismicity from ~841 seismic events in the year 2005 to ~1588 seismic events in 2008...

  17. Isolation of homoleptic platinum oxyanionic complexes with doubly protonated diazacrown cation

    Science.gov (United States)

    Vasilchenko, Danila; Tkachev, Sergey; Baidina, Iraida; Romanenko, Galina; Korenev, Sergey

    2017-02-01

    Doubly protonated diazacrown ether cation (1,4,10,13-tetraoxa-7,16-diazoniacyclooctadecane DCH22+) was used for the efficient isolation of the homoleptic platinum complexes [Pt(NO3)6]2- and [Pt(C2O4)2]2- to crystalline solid phases from solutions containing mixtures of related platinum complexes. DCH22+ molecules in nitric acid solution were shown to prevent the condensation of mononuclear [Pt(H2O)n(NO3)6-n]n-2 species.

  18. Low-energy electron scattering from pyrimidine: Similarities and differences with benzene

    Science.gov (United States)

    Jones, D. B.; Bellm, S. M.; Limão-Vieira, P.; Brunger, M. J.

    2012-05-01

    Differential cross sections for low-energy electron-impact excitation of the unresolved combinations of 23B2 + 21A1 and 31A1 + 21B2 electronic states of pyrimidine are reported. Comparisons are made with recent differential cross section measurements for the electron-impact excitation of the 1E1u and unresolved 1B1u + 3E2g electronic states of benzene [H. Kato, M. Hoshino, H. Tanaka, P. Limão-Vieira, O. Ingolfsson, L. Campbell, M.J. Brunger, J. Chem. Phys. 134 (2011) 134308.], in order to evaluate the nature of electron impact π-π∗ transitions in aromatic species.

  19. The role of interleukin-8 (IL-8) and IL-8 receptors in platinum response in high grade serous ovarian carcinoma.

    Science.gov (United States)

    Stronach, Euan A; Cunnea, Paula; Turner, Christina; Guney, Tankut; Aiyappa, Radhika; Jeyapalan, Senthuran; de Sousa, Camila H; Browne, Alacoque; Magdy, Nesreen; Studd, James B; Sriraksa, Ruethairat; Gabra, Hani; El-Bahrawy, Mona

    2015-10-13

    Platinum based drugs are the cornerstone of chemotherapy for ovarian cancer, however the development of chemoresistance hinders its success. IL-8 is involved in regulating several pro-survival pathways in cancer. We studied the expression of IL-8 and IL-8 receptors in platinum sensitive and resistant cell lines. Using qRT-PCR and immunohistochemistry, both platinum sensitive (PEA1, PEO14) and resistant (PEA2, PEO23) show increased expression of IL-8 and IL-8 receptors. IL-8RA shows nuclear and cytoplasmic expression, whilst IL-8RB is present solely in the cytoplasm. Knockdown of IL-8 increased sensitivity to cisplatin in platinum sensitive and reversed platinum resistance in resistant cell lines, decreased the expression of anti-apoptotic Bcl-2 and decreased inhibitory phosphorylation of pro-apoptotic Bad. IL-8 receptor antagonist treatment also enhanced platinum sensitivity. Nuclear localisation of IL-8RA was only detected in platinum resistant tumours. Inhibition of IL-8 signalling can enhance response in platinum sensitive and resistant disease. Nuclear IL-8RA may have potential as a biomarker of resistant disease.

  20. Cyclic voltammetric investigations of microstructured and platinum-covered glassy carbon electrodes in contact with a polymer electrolyte membrane

    Energy Technology Data Exchange (ETDEWEB)

    Scherer, G G; Veziridis, Z; Staub, M [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Freimuth, H [Inst. fuer Mikrotechnik Mainz IMM, Mainz (Germany)

    1997-06-01

    Model gas diffusion electrodes were prepared by microstructuring glassy carbon surfaces with high aspect ratios and subsequent deposition of platinum. These electrodes were characterized by hydrogen under-potential deposition (H-upd) in contact with a polymer electrolyte membrane employing cyclic voltametry. H-upd was found on platinum areas not in direct contact to the solid electrolyte, as long as a continuous platinum-path existed. A carbon surface between platinum acts as barrier for H-upd. (author) 4 figs., 5 refs.

  1. DNA polymerase η modulates replication fork progression and DNA damage responses in platinum-treated human cells

    Science.gov (United States)

    Sokol, Anna M.; Cruet-Hennequart, Séverine; Pasero, Philippe; Carty, Michael P.

    2013-11-01

    Human cells lacking DNA polymerase η (polη) are sensitive to platinum-based cancer chemotherapeutic agents. Using DNA combing to directly investigate the role of polη in bypass of platinum-induced DNA lesions in vivo, we demonstrate that nascent DNA strands are up to 39% shorter in human cells lacking polη than in cells expressing polη. This provides the first direct evidence that polη modulates replication fork progression in vivo following cisplatin and carboplatin treatment. Severe replication inhibition in individual platinum-treated polη-deficient cells correlates with enhanced phosphorylation of the RPA2 subunit of replication protein A on serines 4 and 8, as determined using EdU labelling and immunofluorescence, consistent with formation of DNA strand breaks at arrested forks in the absence of polη. Polη-mediated bypass of platinum-induced DNA lesions may therefore represent one mechanism by which cancer cells can tolerate platinum-based chemotherapy.

  2. Effect of the platinum content on the microstructure and micropore size distribution of Pt/alumina-pillared clays.

    Science.gov (United States)

    Barrera-Vargas, M; Valencia-Rios, J; Vicente, M A; Korili, S A; Gil, A

    2005-12-15

    The aim of this work is to study the effect of the platinum content (0-1.8 wt % Pt) on the microstructure of an alumina-pillared clay. For this purpose, the nitrogen physisorption data at -196 degrees C, the micropore size distributions of the supported platinum catalysts, and the hydrogen chemisorption results at 30 degrees C have been analyzed and compared. The preparation of the catalysts has modified the textural properties of the Al-pillared clay support, giving rise to a loss of surface area and micropore volume. After reduction at 420 degrees C, the presence of dispersed metallic platinum with mean crystallite size in the 22-55 A range has been found by hydrogen adsorption. Comparison of all results reveals that the platinum species block the micropore entrances by steric hindrance to nitrogen access as the platinum content increases.

  3. Efficient light-emitting devices based on platinum-complexes-anchored polyhedral oligomeric silsesquioxane materials

    KAUST Repository

    Yang, Xiaohui

    2010-08-24

    The synthesis, photophysical, and electrochemical characterization of macromolecules, consisting of an emissive platinum complex and carbazole moieties covalently attached to a polyhedral oligomeric silsesquioxane (POSS) core, is reported. Organic light-emitting devices based on these POSS materials exhibit a peak external quantum efficiency of ca. 8%, which is significantly higher than that of the analogous devices with a physical blend of the platinum complexes and a polymer matrix, and they represent noticeable improvement in the device efficiency of solution-processable phosphorescent excimer devices. Furthermore, the ratio of monomer and excimer/aggregate electroluminescent emission intensity, as well as the device efficiency, increases as the platinum complex moiety presence on the POSS macromolecules decreases. © 2010 American Chemical Society.

  4. Determination of platinum group metals by ICP-AES in environmental samples after preconcentration

    International Nuclear Information System (INIS)

    Vlasankova, R.; Sommer, L.

    1999-01-01

    Platinum group metal (PGM) may have toxic properties and their presence in the environment represent danger for human health. With the introduction of automobile catalytic converters containing PGM, the emission of these noble metals into atmosphere has increased. Platinum, palladium and rhodium are used in this catalytic converters to decrease toxic emissions of carbon monoxide, unburnt hydrocarbons and nitrogen oxides in vehicles exhaust gases. These catalysts are mobile sources of PGM into the environment. Thus, increased platinum concentrations have been found in various objects of environment because of the massive introduction of such catalytic converters are present. The preconcentration and separation of PGM and their determination by ICP-AES in environmental samples are described

  5. Ergonomics of locomotive design in South African Gold and Platinum mines.

    CSIR Research Space (South Africa)

    Smith, JR

    2002-03-01

    Full Text Available to determine reach, posture, field of view and control locations for the operator. • determining the design modifications, which would improve the overall operation of the mine locomotives in South African gold and platinum mines • formu... Acknowledgements Invaluable contributions from the following people are acknowledged: Mr J Annandale Impala Platinum Ltd., Shaft No. 1 Mr W Birmingham Joel Gold Mining Company Ltd. Mr W Brits Anglogold Ltd., Savuka Mine Mr G Burger Anglogold Ltd, West Wits...

  6. Retained sensitivity to cytotoxic pyrimidine nucleoside analogs in thymidine kinase 2 deficient human fibroblasts

    OpenAIRE

    Bjerke, Mia; Solaroli, Nicola; Lesko, Nicole; Balzarini, Jan; Johansson, Magnus; Karlsson, Anna

    2010-01-01

    Thymidine kinase 2 (TK2) is a mitochondrial deoxyribonucleoside kinase that phosphorylates several nucleoside analogs used in anti-viral and anti-cancer therapy. A fibroblast cell line with decreased TK2 activity was investigated in order to obtain insights in the effects of TK2 deficiency on nucleotide metabolism. The role of TK2 for the sensitivity against cytotoxic nucleoside analogs was also investigated. The TK2 deficient cells retained their sensitivity against all pyrimidine nucleoside...

  7. Identification of a large genomic region in UV-irradiated human cells which has fewer cyclobutane pyrimidine dimers than most genomic regions

    International Nuclear Information System (INIS)

    Kantor, G.J.; Deiss-Tolbert, D.M.

    1995-01-01

    Size separation after UV-endonuclease digestion of DNA from UV-irradiated human cells using denaturing conditions fractionates the genome based on cyclobutane pyrimidine dimer content. We have examined the largest molecules available (50-80 kb; about 5% of the DNA) after fractionation and those of average size (5-15 kb) for content of some specific genes. We find that the largest molecules are not a representative sampling of the genome. Three contiguous genes located in a G+C-rich isochore (tyrosine hydroxylase, insulin, insulin-like growth factor II) have concentrations two to three times greater in the largest molecules. This shows that this genomic region has fewer pyrimidine dimers than most other genomic regions. In contrast, the β-actin genomic region, which has a similar G+C content, has an equal concentration in both fractions as do the p53 and β-globin genomic regions, which are A+T-rich. These data show that DNA damage in the form of cyclobutane pyrimidine dimers occurs with different probabilities in specific isochores. Part of the reason may be the relative G-C content, but other factors must play a significant role. We also report that the transcriptionally inactive insulin region is repaired at the genome-overall rate in normal cells and is not repaired in xeroderma pigmentosum complementation group C cells. (author)

  8. Electro-optical and charge injection investigations of the donor-π-acceptor triphenylamine, oligocene–thiophene–pyrimidine and cyanoacetic acid based multifunctional dyes

    Directory of Open Access Journals (Sweden)

    Ahmad Irfan

    2015-10-01

    Full Text Available The corner stone of present study is to tune the electro-optical and charge transport properties of donor-bridge-acceptor (D-π-A triphenylamine (TPA derivatives. In the present investigation, an electron deficient moiety (pyrimidine, electron-rich moiety (thiophene and oligocene (benzene, naphthalene, anthracene, tetracene and pentacene have been incorporated as π-spacer between the donor TPA unit and cyanoacetic acid acceptor and anchoring group. The elongation of bridge usually affects the energy levels, i.e., higher the highest occupied molecular orbital (HOMO while lower the lowest unoccupied molecular orbital (LUMO thus reduces the HOMO–LUMO energy gap. The lowered LUMO energy levels of cyano-{2-[6-(4-diphenylamino-phenyl-pyrimidin-4-yl]-tetraceno[2,3-b]thiophen-8-yl}-acetic acid (TPA-PTT4 and cyano-{2-[6-(4-diphenylamino-phenyl-pyrimidin-4-yl]-pentaceno[2,3-b]thiophen-9-yl}-acetic acid (TPA-PPT5 dyes revealed that electron injected from dye to semiconductor surface might be auxiliary stable resulting in impediment of quenching. The broken co-planarity between the π-spacer conceiving LUMO and the TPA moiety would help to impede the recombination process. Moreover, it is expected that TPA derivatives with the tetracenothiophene and pentacenothiophene moieties as π-bridge would show better photovoltaic performance due to lowered LUMO energy level, higher electronic coupling constant, light harvesting efficiency and electron injection values.

  9. Pyrimidine nucleoside analogues, potential chemotherapeutic agents, and substrates/inhibitors in various enzyme systems

    International Nuclear Information System (INIS)

    Kulikowski, T.; Bretner, M.; Felczak, K.; Drabikowska, A.; Shugar, D.

    1998-01-01

    Full text. Pyrimidine nucleoside analogues are an important class of compounds with antimetabolic (antitumor, antiparasitic and antiviral) properties. The synthesis of thiated nucleoside and nucleotide analogues, determination of structures, conformation and dissociation constans, their potential chemotherapeutic activities, and their substrate/inhibitor properties in various enzyme systems, with emphasis on enzymes related to chemotherapeutic activities, were investigated. In the series of thionated inhibitors of thymidylate synthase (TS), potential antitumor agents, regioselective syntheses were elaborated for 2- and 4-thio, and 2,4-dithio derivatives of 2'-deoxyuridine (dUrd), 5-fluoro-2'-deoxyuridine (FdUrd), and several other 5-fluoro-, 5-bromo- and 5-trifluoromethyl congeners, and the 2-thio derivatives of FdUrd and its α-anomer, which proved to be selective agents with high cytotoxicities correlated with the inhibitory activities vs TS of their corresponding 5'-monophosphates. Regioslective syntheses were also elaborated for 2'-deoxycytidin e and 5-fluoro-2'-deoxycitidine derivatives. Solution conformation of these nucleosides were deduced from high-resolution (500 MHz) 1 H NMR spectra. Substrate/inhibitor properties of 2-thio-2'-deoxycitidine (S 2 dCyd) and 5-fluoro-2-thio-2'-deoxycitidine ( S 2 FdCyd) with respect to human leukemic spleen deoxycytidine kinase have been examined. Both are substrates, and also good inhibitors, of phosphorylation of 2'-deoxycitidine and 2'-deoxyadenosine. Particular attention was directed to the specificity of t he NTP phosphate donor for several nucleoside kinases, and procedures have been developed for distinguishing between ATP and other NTP donors, a problem of importance in chemotherapy with nucleoside analogues. Biological properties of the newly synthetize d thiated pyrimidine 2',3'-dideoxy-3'-fluoronucleosides, S 2 ,3'-FddUrd and S 2 ,3'-FddThd, were also investigated. Thiated 3'-fluoronucleosides were moderate

  10. Spatio-temporal dynamics of oscillatory heterogeneous catalysis: CO oxidation on platinum

    Science.gov (United States)

    Yamamoto, S. Y.; Surko, C. M.; Maple, M. B.; Pina, R. K.

    1995-06-01

    Reaction-rate oscillations in the oxidation of carbon monoxide on the surface of platinum catalysts are studied in a continuous flow reactor at atmospheric pressure using infrared imaging. Small-amplitude temperature oscillations (0.2-8 K) result in approximately isothermal conditions, where changes in rate constants, for typical activation energies and temperatures, are small. The catalysts are in the form of platinum thin films on quartz substrates and provide highly repeatable oscillatory behavior. The platinum films are fabricated in the form of annular rings which provide a quasi-one-dimensional geometry in order to simplify comparison to theoretical models. Time-series measurements by means of thermocouples are used to characterize the oscillations. The infrared images show that most oscillations are spatially synchronized to within the 0.25 s time resolution of the experiment. The images also show that ``fine structure'' oscillations (i.e., small-amplitude, high frequency oscillations superimposed on larger-amplitude waveforms) are associated with spatially desynchronized patterns.

  11. Mechanooptic Regulation of Photoconduction in Functionalized Carbon Nanotubes Decorated with Platinum

    Directory of Open Access Journals (Sweden)

    C. Mercado-Zúñiga

    2014-01-01

    Full Text Available The observation of photoconduction and nonlinear optical absorption on functionalized multiwall carbon nanotubes decorated with platinum is reported. The samples were prepared by a chemical vapor deposition method. The electrical conductivity of the carbon nanotubes seems to be decreased by the functionalization process; but this property is strongly enhanced after the incorporation of platinum particles. Nonresonant photoconductive experiments at 532 nm and 445 nm wavelengths allow us to detect a selective participation of the platinum to the photoelectrical response. A mechanooptic effect based on Fresnel reflection was obtained through a photoconductive modulation induced by the rotation of a silica substrate where the samples were deposited as a thin film. A two-photon absorption process was identified as the main physical mechanism responsible for the nonlinear optical absorption. We consider that important changes in the nonlinear photon interactions with carbon nanotubes can be related to the population losses derived from phonons and the detuning of the frequency originated by functionalization.

  12. [Separation of purines, pyrimidines, pterins and flavonoids on magnolol-bonded silica gel stationary phase by high performance liquid chromatography].

    Science.gov (United States)

    Chen, Hong; Li, Laishen; Zhang, Yang; Zhou, Rendan

    2012-10-01

    A new magnolol-bonded silica gel stationary phase (MSP) was used to separate the basic drugs including four purines, eight pyrimidines, four pterins and five flavonoids as polar representative samples by high performance liquid chromatography (HPLC). To clarify the separation mechanism, a commercial ODS column was also tested under the same chromatographic conditions. The high selectivities and fast baseline separations of the above drugs were achieved by using simple mobile phases on MSP. Although there is no end-caped treatment, the peak shapes of basic drugs containing nitrogen such as purines, pyrimidines and pterins were rather symmetrical on MSP, which indicated the the magnolol as ligand with multi-sites could shield the side effect of residual silanol groups on the surface of silica gel. Although somewhat different in the separation resolution, it was found that the elution orders of some drugs were generally similar on both MSP and ODS. The hydrophobic interaction should play a significant role in the separations of the above basic drugs, which was attributed to their reversed-phase property in the nature. However, MSP could provide the additional sites for many polar solutes, which was a rational explanation for the high selectivity of MSP. For example, in the separation of purines, pyrimidines and pterins on MSP, hydrogen-bonding and dipole-dipole interactions played leading roles besides hydrophobic interaction. Some solute molecules (such as mercaptopurine, vitexicarpin) and MSP can form the strong pi-pi stacking in the separation process. All enhanced the retention and improved the separation selectivity of MSP, which facilitated the separation of the basic drugs.

  13. In vitro free radical scavenging activity of platinum nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Aki; Kajita, Masashi; Kim, Juewon; Kanayama, Atsuhiro; Miyamoto, Yusei [Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Bioscience Building 402, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8562 (Japan); Takahashi, Kyoko; Mashino, Tadahiko, E-mail: yusei74@k.u-tokyo.ac.j [Department of Pharmaceutical Sciences, Faculty of Pharmacy, Keio University, 1-5-30 Shibakoen, Minato, Tokyo 105-8512 (Japan)

    2009-11-11

    A polyacrylic acid (PAA)-protected platinum nanoparticle species (PAA-Pt) was prepared by alcohol reduction of hexachloroplatinate. The PAA-Pt nanoparticles were well dispersed and homogeneous in size with an average diameter of 2.0 {+-} 0.4 nm (n = 200). We used electron spin resonance to quantify the residual peroxyl radical AOO. generated from 2,2-azobis (2-aminopropane) dihydrochloride (AAPH) by thermal decomposition in the presence of O{sub 2} and a spectrophotometric method to quantify the residual 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. PAA-Pt scavenged these two radicals in a dose-dependent manner. Platinum was the functional component. PAA-Pt reduced the rate of oxygen consumption required for linoleic acid peroxidation initiated by AOO. generated from AAPH, indicating inhibition of the propagation of linolate peroxidation. A thiobarbituric acid test also revealed dose-dependent inhibition of the linolate peroxidation by PAA-Pt. Fifty micromolar platinum, as PAA-Pt, completely quenched 250 {mu}M DPPH radical for 5 min. Even when twice diluted in half, the PAA-Pt still quenched 100% of the 250 {mu}M DPPH radical. The scavenging activity of PAA-Pt is durable. These observations suggest that PAA-Pt is an efficient scavenger of free radicals.

  14. Modeling of Platinum-Aryl Interaction with Amyloid-β Peptide.

    Science.gov (United States)

    Turner, Matthew; Platts, James A; Deeth, Robert J

    2016-03-08

    Ligand field molecular mechanics (LFMM), density functional theory (DFT), and semiempirical PM7 methods are used to study the binding of two Pt(II)-L systems to an N-terminal fragment of the amyloid-β peptide, where L = 2,2-bipyridyl or 1,10-phenanthroline. Molecular dynamics simulations are used to explore the conformational freedom of the peptide using LFMM combined with AMBER molecular mechanics parameters. We establish a modeling protocol, allowing for identification and analysis of favorable platinum-binding modes and peptide conformations. Preferred binding modes are identified for each ligand investigated; metal coordination occurs via Nε in His residues for both ligands--His6ε-His13ε and His6ε-His14ε for the bipyridyl and phenanthroline ligands, respectively. The observed change in binding mode for the different ligands suggests that the binding mode of these platinum-based structures can be controlled by the choice of ligand. In the bipy systems, Boltzmann population at 310 K is dominated by a single conformer, while in the phenanthroline case, three conformations make significant contributions to the ensemble. The relative stability of these conformations is due to the inherent stability of binding platinum via Nε in addition to subtle H-bonding effects.

  15. Structural consideration with respect to the thermal stability of a new platinum supported lanthanum-alumina catalyst

    International Nuclear Information System (INIS)

    Oudet, F.; Bordes, E.; Courtine, P.; Maxant, G.; Lambert, C.; Guerlet, J.P.

    1987-01-01

    The influence of lanthanum aluminate, LaAlO 3 , on the thermal stability of both alumina and platinum supported alumina catalysts is investigated. In the case of alumina, the stabilization is interpreted in terms of structural coherence between δ-Al 2 O 3 and a three-fold superstructure of LaAlO 3 . The addition of LaAlO 3 , is shown to increase both the dispersion and the resistance to sintering of the platinum supported alumina catalyst. Moreover, lanthanum hexa-aluminate (La-β-Al 2 O 3 ) is present in the platinum catalyst fired at 1150 0 C. These observations are assumed to result for the epitaxial relations between platinum and the lanthanum-alumina support. 23 refs.; 8 figs.; 2 tabs

  16. A sensitivity study of the oxidation of compressed natural gas on platinum

    KAUST Repository

    Badra, Jihad

    2013-11-01

    This paper presents a sensitivity study for the oxidation of methane (CH4) over platinum (Pt). Some dominant reactions in the CH 4-Pt surface chemistry were identified and the rates of these reactions were subsequently modified to enhance the calculations. Initially, a range of CH4-Pt surface mechanisms available in the literature are used, along with the relevant detailed gaseous chemistry to compute the structure of premixed compressed natural gas (CNG)/air flames co-flowing around a flat, vertical, unconfined, rectangular, and platinum plate. Comparison with existing measurements of surface temperature and species concentrations revealed significant discrepancies for all mechanisms. Sensitivity analysis has identified nine key reactions which dominate the heterogeneous chemistry of methane over platinum. The rates of these reactions were modified over a reasonable range and in different combinations leading to an "optimal" mechanism for methane/air surface chemistry on platinum. The new mechanism is then used with the same flow geometry for different cases varying the temperature of the incoming mixture (Tjet), its equivalence ratio (Φ) and the Reynolds number (Re). Results from the modified surface mechanism demonstrate reasonably good agreement with the experimental data for a wide range of operating conditions. © 2013 Elsevier Ltd. All rights reserved.

  17. Synthesis of New Visnagen and Khellin Furochromone Pyrimidine Derivatives and Their Anti-Inflammatory and Analgesic Activity

    Directory of Open Access Journals (Sweden)

    Ameen Ali Abu-Hashem

    2011-02-01

    Full Text Available 6-[(4-Methoxy/4,9-dimethoxy-7-methylfurochromen-5-ylideneamino]-2-thioxo-2,3-dihydropyrimidin-4-ones 1a,b were prepared by reaction of 6-amino-2-thiouracil with visnagen or khellin, respectively. Reaction of 1a,b with methyl iodide afforded furochromenylideneaminomethylsulfanylpyrimidin-4-ones 2a,b. Compounds 2a,b were reacted with secondary aliphatic amines to give the corresponding furochromen-ylideneamino-2-substituted pyrimidin-4-ones 3a–d. Reaction of 3a–d with phosphorus oxychloride yielded 6-chlorofurochromenylidenepyrimidinamines 4a–d, which were reacted with secondary amines to afford furochromenylideneamino-2,6-disubstituted pyrimidin-4-ones 5a–d. In addition, reaction of 5a–d with 3-chloropentane-2,4-dione gave 3-chloro-furochromenylpyrimidopyrimidines 6a–d. The latter were reacted with piperazine and morpholine to give 1-(furochromenyl-pyrimidopyrimidine-3,6,8-triylpiperazines or -3,6,8-triylmorpholines 7a–d. The chemical structures of the newly synthesized compound ware characterized by IR, 1H-NMR, 13C-NMR and mass spectral analysis. These compounds were also screened for their analgesic and anti-inflammatory activities. Some of them, particularly 3–7, exhibited promising activities.

  18. Depression of pyrimidine dimer excision from the aspects of uv reversibility of irradiated cells

    Energy Technology Data Exchange (ETDEWEB)

    Slamenova, D; Slezarikova, V; Masek, F [Slovenska Akademia Vied, Bratislava (Czechoslovakia)

    1977-04-01

    Depression of pyrimidine dimer excision induced in uv-irradiated E.coli B/r T/sup -/trp/sup -/Hcr/sup +/ cells by preirradiation cultivation in conditions of starving for the essential amino acid and thymine does not increase uv-reversibility of irradiated cells and does not influence the time of expression of trp/sup +/ reversions. The expression of mutations becomes completed in control and prestarved cells prior to restoration of postradiation division. Genetic deficiency leads up to their high sensitivity to the mutagenic activity of uv irradiation. Expression of trp/sup +/ revertants in Hcr/sup -/ type cells does not become completed until after commencement of the postradiation division of irradiated cells. Prestarved E.coli B/r T/sup -/trp/sup -/Hcr/sup +/ cells exhibited depression of excision even with postradiation cultivation in the absence of an essential amino acid, which is associated with greater stability of newly synthesized DNA and overall decrease of the death rate of cells. In postradiation starvation for the essential amino acid E.coli B/r T/sup -/trp/sup -/Hcr/sup -/ cells irradiated with low uv light doses behaved similarly. Control E.coli B/r T/sup -/trp/sup -/Hcr/sup +/ cells, cultivated after irradiation without amino acid, excised pyrimidine dimers; they are characterised by high degradation of newly synthesized DNA and increased death rate of cells.

  19. MULTICOMPONENT AND REGIOSELECTIVE SYNTHESIS OF DIHYDROPYRAZOLO[1,5-a]PYRIMIDINES FROM AROMATIC ALDEHYDES, MELDRUM'S ACID AND AMINOPYRAZOLE CAN508

    Czech Academy of Sciences Publication Activity Database

    Jedinák, L.; Kryštof, Vladimír; Trávníček, Z.; Cankař, P.

    2014-01-01

    Roč. 89, č. 8 (2014), s. 1892-1904 ISSN 0385-5414 R&D Projects: GA MŠk(CZ) LO1204 Institutional support: RVO:61389030 Keywords : Pyrazolo[1,5-a]pyrimidine * Cyclization * Multicomponent Reaction Subject RIV: CC - Organic Chemistry Impact factor: 1.079, year: 2014

  20. Depression of pyrimidine dimer excision from the aspects of U.V. reversibility of irradiated cells

    International Nuclear Information System (INIS)

    Slamenova, D.; Slezarikova, V.; Masek, F.

    1977-01-01

    Depression of pyrimidine dimer excision induced in U.V. irradiated E.coli B/r T - trp - Hcr + cells by preirradiation cultivation in conditions of starving for the essential amino acid and thymine does not increase U.V.-reversibility of irradiated cells and does not influence the time of expression of trp + reversions. The expression of mutations becomes completed in control and prestarved cells prior to restoration of postradiation division. Genetic deficiency leads up to their high sensitivity to the mutagenic activity of U.V. irradiation. Expression of trp + revertants in Hcr - type cells does not become completed until after commencement of the postradiation division of irradiated cells. Prestarved E.coli B/r T - trp - Hcr + cells exhibited depression of excision even with postradiation cultivation in the absence of an essential amino acid, which is associated with greater stability of newly synthesized DNA and overall decrease of the death rate of cells. In postradiation starvation for the essential amino acid E.coli B/r T - trp - Hcr - cells irradiated with low U.V. light doses behaved similarly. Control E.coli B/r T - trp - Hcr + cells, cultivated after irradiation without amino acid, excised pyrimidine dimers; they are characterised by high degradation of newly synthesized DNA and increased death rate of cells. (author)

  1. Steroidal[17,16-d]pyrimidines derived from dehydroepiandrosterone: A convenient synthesis, antiproliferation activity, structure-activity relationships, and role of heterocyclic moiety

    Science.gov (United States)

    Ke, Shaoyong; Shi, Liqiao; Zhang, Zhigang; Yang, Ziwen

    2017-01-01

    A series of steroidal[17,16-d]pyrimidines derived from dehydroepiandrosterone were designed and prepared by a convenient heterocyclization reaction. The in vitro anticancer activities for these obtained compounds were evaluated against human cancer cell lines (HepG2, Huh-7, and SGC-7901), which demonstrated that some of these heterocyclic pyrimidine derivatives exhibited significantly good cytotoxic activities against all tested cell lines compared with 5-fluorouracil (5-FU), especially, compound 3b exhibited high potential growth inhibitory activities against all tested cell lines with the IC50 values of 5.41 ± 1.34, 5.65 ± 1.02 and 10.64 ± 1.49 μM, respectively, which might be used as promising lead scaffold for discovery of novel anticancer agents. PMID:28290501

  2. Preliminary study of platinum accumulation in the fruitbodies of a model fungal species: king oyster mushroom (Pleurotus eryngii)

    International Nuclear Information System (INIS)

    Urban, P.L.; Bazala, M.A.; Bystrzejewska-Piotrowska, G.; Pianka, D.; Steborowski, R.; Asztemborska, M.; Kowalska, J.; Manjon, J.L.; Kuthan, R.T.

    2005-01-01

    A model species of saprophytic fungus, king oyster mushroom (Pleurotus eryngii), was cultivated on barley substrate supplied with [Pt(NH 3 ) 4 ](NO 3 ) 2 , under well defined conditions. The samples of the collected fruiting bodies were digested and analyzed for total platinum content by means of ICP-MS. The results proved that platinum is not accumulated in the fruitbodies of Pleurotus eryngii for a wide range of Pt concentrations in the culture substrate (100-1000 ppb Pt in 50 ml of water solution added to ca. 450 g of hydrated barley seeds per container). Observable levels of Pt were only found in the fruitbodies obtained from the medium contaminated with 10000 ppb (10 ppm) platinum solution. This demonstrates significant difference in the effectiveness of platinum extraction in fungi and plants, which are capable to accumulate platinum even when supplied at lower concentration (<500 ppb). It also shows different physiological pathways of platinum and other elements which are easily accumulated in the fruitbodies of the same species. (author)

  3. Levels and Speciation of Platinum in Size-Fractionated Atmospheric Aerosol in Urban and Rural Sites across Europe

    Science.gov (United States)

    Shafer, Martin; Antkiewicz, Dagmara; Overdier, Joel; Schauer, James

    2016-04-01

    In this study we characterized the levels and speciation of platinum in a unique set of size-resolved atmospheric aerosol (PM) samples obtained from urban environments across Europe. From April-July 2012 we collected PM from roadside canyon, roadside motorway, and background urban sites in each of six European cities (Amsterdam, Frankfurt, London, Milan, Stockholm, and Thessaloniki). A Hi-Vol sampler was used to collect PM in three size classes (>PM7, PM7-PM3, PM3) and characterized for total platinum, soluble platinum (in a suite of physiologically relevant fluids - lung fluid (ALF), Gambles saline, 0.07M HCl, and MQ) and speciated forms (colloidal and anionic) within the soluble fractions. In addition we measured 50 other elements by SF-ICPMS, soluble ions by IC, and soluble organic carbon in the PM. Order-of-magnitude differences in air concentrations of total platinum were observed between urban sites, ranging from 4 to over 45 pg/m3; with a median level of 6 pg/m3. When platinum concentrations are normalized to PM mass the cross Europe and site-to-site variability was substantially reduced - a 3-fold variation from 200 to 600 ng/g was observed. Roadside canyon sites in London, Stockholm and Thessaloniki exhibited the highest concentrations; however levels at urban background sites were remarkably similar across the cities. Relatively consistent and low concentrations (1 to 2 pg/m3) of total platinum were observed at rural background sites across Europe. The contribution of coarse particles (>7 micron and 7-3 micron) to air concentrations of total platinum was very significant (>35% at nearly all sites). Soluble platinum fractions ranged from 2 to 6% (MQ to HCl) in rural background sites to 5 to 20% (MQ to HCl) in roadway canyon sites in London and Thessaloniki; with the extractable platinum fractions a strong function of pH. With the exception of urban canyon sites in London and Thessaloniki, soluble platinum concentrations in the fine aerosol (PM3) were all

  4. Effects of para-substituents of styrene derivatives on their chemical reactivity on platinum nanoparticle surfaces

    Science.gov (United States)

    Hu, Peiguang; Chen, Limei; Deming, Christopher P.; Lu, Jia-En; Bonny, Lewis W.; Chen, Shaowei

    2016-06-01

    Stable platinum nanoparticles were successfully prepared by the self-assembly of para-substituted styrene derivatives onto the platinum surfaces as a result of platinum-catalyzed dehydrogenation and transformation of the vinyl groups to the acetylene ones, forming platinum-vinylidene/-acetylide interfacial bonds. Transmission electron microscopic measurements showed that the nanoparticles were well dispersed without apparent aggregation, suggesting sufficient protection of the nanoparticles by the organic capping ligands, and the average core diameter was estimated to be 2.0 +/- 0.3 nm, 1.3 +/- 0.2 nm, and 1.1 +/- 0.2 nm for the nanoparticles capped with 4-tert-butylstyrene, 4-methoxystyrene, and 4-(trifluoromethyl)styrene, respectively, as a result of the decreasing rate of dehydrogenation with the increasing Taft (polar) constant of the para-substituents. Importantly, the resulting nanoparticles exhibited unique photoluminescence, where an increase of the Hammett constant of the para-substituents corresponded to a blue-shift of the photoluminescence emission, suggesting an enlargement of the HOMO-LUMO band gap of the nanoparticle-bound acetylene moieties. Furthermore, the resulting nanoparticles exhibited apparent electrocatalytic activity towards oxygen reduction in acidic media, with the best performance among the series of samples observed with the 4-tert-butylstyrene-capped nanoparticles due to an optimal combination of the nanoparticle core size and ligand effects on the bonding interactions between platinum and oxygen species.Stable platinum nanoparticles were successfully prepared by the self-assembly of para-substituted styrene derivatives onto the platinum surfaces as a result of platinum-catalyzed dehydrogenation and transformation of the vinyl groups to the acetylene ones, forming platinum-vinylidene/-acetylide interfacial bonds. Transmission electron microscopic measurements showed that the nanoparticles were well dispersed without apparent

  5. Green Transformational Leadership and Green Performance: The Mediation Effects of Green Mindfulness and Green Self-Efficacy

    OpenAIRE

    Yu-Shan Chen; Ching-Hsun Chang; Yu-Hsien Lin

    2014-01-01

    No prior literature explores the influence of green transformational leadership on green performance, thus, this study develops a novel research framework to fill the research gap. This study investigates the influence of green transformational leadership on green performance and discusses the mediation effects of green mindfulness and green self-efficacy by means of structural equation modeling (SEM). The results indicate that green transformational leadership positively influences green min...

  6. 31P-NMR study of human pyrimidine 5'-nucleotidase deficient erythrocytes

    International Nuclear Information System (INIS)

    Higaki, Tsuyoshi; Kagimoto, Tadashi; Nagata, Koichi; Tanase, Sumio; Morino, Yoshimasa; Takatsuki, Kiyoshi

    1982-01-01

    Metabolic disorder of nucleotides in human pyrimidine 5'-nucleotidase (P5N) deficient erythrocytes was studied by 31 P-NMR with high resolution. Identification by combination of high-speed liquid chromatography revealed two-fold increases from the normal in the spectra in the α-, β- and γ-zones of nucleoside triphosphates of P5N deficient erythrocytes, 2,3-diphosphoglycerate shifted to the 0.3 ppm low magnetic field and signals of NAD and UDP-sugars(s) in the diphosphodiester zone. These results were obtained from the 31 P-NMR spectrum about one hour after blood sampling, indicating the high utility of this NMR for the diagnosis of P5N deficiency. (Chiba, N.)

  7. Synthesis, reactions, and antiarrhythmic activities of some novel pyrimidines and pyridines fused with thiophene moiety

    OpenAIRE

    AMR, Abdel-Galil El-Sayed; ABDEL-HAFEZ, Naglaa Abdel-Samei

    2009-01-01

    We report herein the synthesis and antiarrhythmic activities of some newly synthesized heterocyclic theino[2,3-c]pyrimidine and theino[2,3-c]pyridine derivatives fused with thiophene moiety. Initially the acute toxicity of the compounds was assayed via the determination of their LD50. The antiarrhythmic activities for the compounds were determined and all the tested compounds were found more potent than Procaine amide\\textregistered and Lidocaine\\textregistered as positive antiarrhyth...

  8. Synthesis, reactions, and antiarrhythmic activities of some novel pyrimidines and pyridines fused with thiophene moiety

    OpenAIRE

    AMR, Abdel-Galil El-Sayed; ABDEL-HAFEZ, Naglaa Abdel-Samei; MOHAMED, Salwa Fahem; ABDALLA, Mohamed Mostafa

    2014-01-01

    We report herein the synthesis and antiarrhythmic activities of some newly synthesized heterocyclic theino[2,3-c]pyrimidine and theino[2,3-c]pyridine derivatives fused with thiophene moiety. Initially the acute toxicity of the compounds was assayed via the determination of their LD50. The antiarrhythmic activities for the compounds were determined and all the tested compounds were found more potent than Procaine amide\\textregistered and Lidocaine\\textregistered as positive antiarrhyth...

  9. Design, Synthesis, and X-ray Crystal Structures of 2,4-Diaminofuro[2,3-d]pyrimidines as Multireceptor Tyrosine Kinase and Dihydrofolate Reductase Inhibitors

    Science.gov (United States)

    Gangjee, Aleem; Li, Wei; Lin, Lu; Zeng, Yibin; Ihnat, Michael; Warnke, Linda A.; Green, Dixy W.; Cody, Vivian; Pace, Jim; Queener, Sherry F.

    2009-01-01

    To optimize dual receptor tyrosine kinase (RTK) and dihydrofolate reductase (DHFR) inhibition, the E- and Z-isomers of 5-[2-(2-methoxyphenyl)prop-1-en-1-yl]furo[2,3-d]pyrimidine-2,4-diamines (1a and 1b) were separated by HPLC and the X-ray crystal structures (2.0 Å and 1.4 Å respectively) with mouse DHFR and NADPH as well as 1b with human DHFR (1.5 Å) were determined. The E- and Z-isomers adopt different binding modes when bound to mouse DHFR. A series of 2,4-diaminofuro[2,3-d]pyrimidines 2–13 were designed and synthesized using the X-ray crystal structures of 1a and 1b with DHFR to increase their DHFR inhibitory activity. Wittig reactions of appropriate 2-methoxyphenyl ketones with 2,4-diamino-6-chloromethyl furo[2,3-d]pyrimidine afforded the C8–C9 unsaturated compounds 2–7 and catalytic reduction gave the saturated 8–13. Homologation of the C9-methyl analog maintains DHFR inhibitory activity. In addition, inhibition of EGFR and PDGFR-β were discovered for saturated C9-homologated analogs 9 and 10 that were absent in the saturated C9-methyl analogs. PMID:19748785

  10. TD-DFT Investigation of the Magnetic Circular Dichroism Spectra of Some Purine and Pyrimidine Bases of Nucleic Acids

    DEFF Research Database (Denmark)

    Fahleson, Tobias; Kauczor, Joanna; Norman, Patrick

    2015-01-01

    We present a computational study of the magnetic circular dichroism (MCD) spectra in the 200–300 nm wavelength region of purine and its derivative hypoxanthine, as well as of the pyrimidine bases of nucleic acids uracil, thymine, and cytosine, using the B3LYP and CAM–B3LYP functionals. Solvent...

  11. Controllable deposition of platinum nanoparticles on single-wall carbon nanohorns as catalyst for direct methanol fuel cells.

    Science.gov (United States)

    Niu, Ben; Xu, Wei; Guo, Zhengduo; Zhou, Nengzhi; Liu, Yang; Shi, Zujin; Lian, Yongfu

    2012-09-01

    Uniform and well dispersed platinum nanoparticles were successfully deposited on single-walled carbon nanohorns with the assistance of 4,4-dipydine and ion liquids, respectively. In particular, the size of platinum nanoparticles could be controlled in a very narrow range (2.2 to 2.5 nm) when ion liquids were applied. The crystalline nature of these platinum nanoparticles was confirmed by high resolution transmission electron microscopy observation and X-ray power diffraction analysis, and two species of platinum Pt(0) and Pt(II) were detected by X-ray photoelectron spectroscopy. Electrochemical studies revealed that thus obtained nanocomposites had much better electrocatalytic activity for the methanol oxidation than those prepared with carbon nanotubes as supporter.

  12. Physical association of pyrimidine dimer DNA glycosylase and apurinic/apyrimidinic DNA endonuclease essential for repair of ultraviolet-damaged DNA

    International Nuclear Information System (INIS)

    Nakabeppu, Y.; Sekiguchi, M.

    1981-01-01

    T4 endonuclease, which is involved in repair of uv-damaged DNA, has been purified to apparent physical homogeneity. Incubation of uv-irradiated poly(dA).poly(dT) with the purified enzyme preparations resulted in production of alkali-labile apyrimidinic sites, followed by formation of nicks in the polymer. By performing a limited reaction with T4 endonuclease V at pH 8.5, irradiated polymer was converted to an intermediate form that carried a large number of alkali-labile sites but only a few nicks. The intermediate was used as substrate for the assay of apurinic/apyrimidinic DNA endonuclease activity. The two activities, a pyrimidine dimer DNA glycosylase and an apurinic/apyrimidinic DNA endonuclease, were copurified and found in enzyme preparations that contained only a 16,000-dalton polypeptide. These results strongly suggested that a DNA glycosylase specific for pyrimidine dimers and an apurinic/apyrimidinic DNA endonuclease reside in a single polypeptide chain coded by the denV gene of bacteriophage T4

  13. Platinum/ceria/alumina catalysts on microstructures for carbon monoxide conversion

    Energy Technology Data Exchange (ETDEWEB)

    Germani, G.; Schuurman, Y.; Mirodatos, C. [Institut de Recherches sur la Catalyse, CNRS, 2 Avenue Albert Einstein, 69626 Villeurbanne (France); Alphonse, P.; Courty, M. [CIRIMAT, UMR-CNRS 5085, Universite Paul Sabatier, 118 route de Narbonne, 31062 Toulouse Cedex 04 (France)

    2005-12-15

    Platinum/ceria/alumina catalysts have been prepared by a sol-gel method and coated in the microchannels of stainless steel platelets. These catalysts are very active for the water-gas shift reaction between 300 and 400{sup o}C. Moreover, they are non-pyrophoric and thus well suited for the purification of hydrogen for PEM fuel cells. The obtained coatings show good adherence and catalytic activity. The influence of the amount of platinum and ceria as well as the effect of a binder on the catalytic performance has been investigated. The samples have been characterized before reaction by XRD, SEM and by N{sub 2} adsorption measurements. The kinetics, free from internal diffusion limitations, over these thin films have been described by a power law rate equation. An activation energy of 86kJ/mol has been found and at 260{sup o}C the TOF corresponds to 0.6+/-0.1s{sup -1} for all investigated samples. The superior activity of the platelets compared to the powder samples is attributed to the diffusion limitations inside the powder pellets. Thus catalysts deposited on microstructured platelets lead to a better platinum utilization.

  14. GREEN PACKAGING, GREEN PRODUCT, GREEN ADVERTISING, PERSEPSI, DAN MINAT BELI KONSUMEN

    Directory of Open Access Journals (Sweden)

    Imam Santoso

    2016-12-01

    Full Text Available Environmental problems become one of the strategic issues in achieving global competitiveness. One of the issues is products that are made from environmental friendly materials or known as green product. Furthermore, in green products marketing, the company also uses green packaging and green advertising concept. This study aimed to analyze the effect of green packaging, green products, and green advertising on consumer perception and purchasing intention. The study was conducted in Ketawanggede Village, Lowokwaru Sub-district, Malang City. The sampling method used nonprobability accidential sampling techniques. The numbers of respondents were 113 consumers in study site. Data were collected by interview using questionnaires. The method of analysis used Generalized Structured Component Analysis (GSCA. The analysis showed that the green packaging, green products, and green advertising had positive significant influence on consumer perceptions. Meanwhile, green product and consumer perception had positive significant influence on purchasing interest, but the green packaging and green advertising has not found sufficient evidence in influencing purchasing intention.

  15. Recycling of platinum group metals from the automotive catalysts

    International Nuclear Information System (INIS)

    Benevit, Mariana; Petter, Patricia Melo Halmenschlager; Veit, Hugo Marcelo

    2014-01-01

    Currently it is very important to use alternative sources of raw material for obtaining metals, avoiding the traditional mining. This work aims to characterize and evaluate the recoverability of platinum group metals present in automotive catalysts. Thus, the catalysts were divided into two groups: the first was catalysts used in 1.0 cars and the second was catalyst used in 2.0 cars. DRX and FRX techniques and chemical analysis performed by ICP/OES was used to characterized these materials. The results showed that there is a significant amount of platinum group elements in catalyst waste, which can be separated and reused. In the next step, hydro and pyrometallurgical routes, for metals extraction from catalyst waste, will be studied. (author)

  16. ENVIRONMENTAL TECHNOLOGY VERIFICATION REPORT, HVLP COATING EQUIPMENT, SHARPE MANUFACTURING COMPANY PLATINUM 2012 HVLP SPRAY GUN

    Science.gov (United States)

    This report presents the results of the verification test of the Sharpe Platinum 2013 high-volume, low-pressure gravity-feed spray gun, hereafter referred to as the Sharpe Platinum, which is designed for use in automotive refinishing. The test coating chosen by Sharpe Manufacturi...

  17. One-electron oxidation reactions of purine and pyrimidine bases in cellular DNA.

    Science.gov (United States)

    Cadet, Jean; Wagner, J Richard; Shafirovich, Vladimir; Geacintov, Nicholas E

    2014-06-01

    The aim of this survey is to critically review the available information on one-electron oxidation reactions of nucleobases in cellular DNA with emphasis on damage induced through the transient generation of purine and pyrimidine radical cations. Since the indirect effect of ionizing radiation mediated by hydroxyl radical is predominant in cells, efforts have been made to selectively ionize bases using suitable one-electron oxidants that consist among others of high intensity UVC laser pulses. Thus, the main oxidation product in cellular DNA was found to be 8-oxo-7,8-dihydroguanine as a result of direct bi-photonic ionization of guanine bases and indirect formation of guanine radical cations through hole transfer reactions from other base radical cations. The formation of 8-oxo-7,8-dihydroguanine and other purine and pyrimidine degradation products was rationalized in terms of the initial generation of related radical cations followed by either hydration or deprotonation reactions in agreement with mechanistic pathways inferred from detailed mechanistic studies. The guanine radical cation has been shown to be implicated in three other nucleophilic additions that give rise to DNA-protein and DNA-DNA cross-links in model systems. Evidence was recently provided for the occurrence of these three reactions in cellular DNA. There is growing evidence that one-electron oxidation reactions of nucleobases whose mechanisms have been characterized in model studies involving aqueous solutions take place in a similar way in cells. It may also be pointed out that the above cross-linked lesions are only produced from the guanine radical cation and may be considered as diagnostic products of the direct effect of ionizing radiation.

  18. Bis-guanylhydrazone diimidazo[1,2-a:1,2-c]pyrimidine as a novel and specific G-quadruplex binding motif.

    Science.gov (United States)

    Sparapani, Silvia; Bellini, Stefania; Gunaratnam, Mekala; Haider, Shozeb M; Andreani, Aldo; Rambaldi, Mirella; Locatelli, Alessandra; Morigi, Rita; Granaiola, Massimiliano; Varoli, Lucilla; Burnelli, Silvia; Leoni, Alberto; Neidle, Stephen

    2010-08-21

    A bis-guanylhydrazone derivative of diimidazo[1,2-a:1,2-c]pyrimidine has unexpectedly been found to be a potent stabiliser of several quadruplex DNAs, whereas there is no significant interaction with duplex DNA. Molecular modeling suggests that the guanylhydrazone groups play an active role in quadruplex binding.

  19. Silica Supported Platinum Catalysts for Total Oxidation of the Polyaromatic Hydrocarbon Naphthalene: An Investigation of Metal Loading and Calcination Temperature

    Directory of Open Access Journals (Sweden)

    David R. Sellick

    2015-04-01

    Full Text Available A range of catalysts comprising of platinum supported on silica, prepared by an impregnation method, have been studied for the total oxidation of naphthalene, which is a representative Polycyclic Aromatic Hydrocarbon. The influence of platinum loading and calcination temperature on oxidation activity was evaluated. Increasing the platinum loading up to 2.5 wt.% increased the catalyst activity, whilst a 5.0 wt.% catalyst was slightly less active. The catalyst containing the optimum 2.5 wt.% loading was most active after calcination in air at 550 °C. Characterisation by carbon monoxide chemisorption and X-ray photoelectron spectroscopy showed that low platinum dispersion to form large platinum particles, in combination with platinum in metallic and oxidised states was important for high catalyst activity. Catalyst performance improved after initial use in repeat cycles, whilst there was slight deactivation after prolonged time-on-stream.

  20. The impact of whole human blood on the kinetic inertness of platinum(iv) prodrugs - an HPLC-ICP-MS study.

    Science.gov (United States)

    Theiner, Sarah; Grabarics, Márkó; Galvez, Luis; Varbanov, Hristo P; Sommerfeld, Nadine S; Galanski, Markus; Keppler, Bernhard K; Koellensperger, Gunda

    2018-04-17

    The potential advantage of platinum(iv) complexes as alternatives to classical platinum(ii)-based drugs relies on their kinetic stability in the body before reaching the tumor site and on their activation by reduction inside cancer cells. In this study, an analytical workflow has been developed to investigate the reductive biotransformation and kinetic inertness of platinum(iv) prodrugs comprising different ligand coordination spheres (respectively, lipophilicity and redox behavior) in whole human blood. The distribution of platinum(iv) complexes in blood pellets and plasma was determined by inductively coupled plasma-mass spectrometry (ICP-MS) after microwave digestion. An analytical approach based on reversed-phase (RP)-ICP-MS was used to monitor the parent compound and the formation of metabolites using two different extraction procedures. The ligand coordination sphere of the platinum(iv) complexes had a significant impact on their accumulation in red blood cells and on their degree of kinetic inertness in whole human blood. The most lipophilic platinum(iv) compound featuring equatorial chlorido ligands showed a pronounced penetration into blood cells and a rapid reductive biotransformation. In contrast, the more hydrophilic platinum(iv) complexes with a carboplatin- and oxaliplatin-core exerted kinetic inertness on a pharmacologically relevant time scale with notable amounts of the compound accumulated in the plasma fraction.

  1. Syntheses and anti-microbial evaluation of new quinoline scaffold derived pyrimidine derivatives

    Directory of Open Access Journals (Sweden)

    Shikha S. Dave

    2016-09-01

    Full Text Available A series of diversely substituted chalcones derived from a quinoline scaffold, e.g. (E-3-(2-chloroquinolin-3-yl-1-(2-hydroxyphenyl prop-2-en-1-one and its pyrimidine analogues e.g. 2-[2-amino-6-(2-chloroquinolin-3-yl-5,6-dihydropyrimidin-4-yl]phenols have been prepared by condensation of 2-chloro-3-formyl quinoline with differently substituted 2-hydroxy acetophenones and further treatment with guanidine carbonate. All the newly synthesized compounds have been evaluated for their in vitro growth inhibitory activity against Escherichia coli, Pseudomonas vulgaris, Bacillus subtilis, Staphylococcus aureus, Staphylococcus typhi, Candida albicans, Aspergillus niger and Pseudomonas chrysogenum.

  2. 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

  3. High platinum utilization in ultra-low Pt loaded PEM fuel cell cathodes prepared by electrospraying

    Energy Technology Data Exchange (ETDEWEB)

    Martin, S.; Garcia-Ybarra, P.L.; Castillo, J.L. [Dept. Fisica Matematica y de Fluidos, Facultad de Ciencias, UNED, Senda del Rey 9, 28040 Madrid (Spain)

    2010-10-15

    Cathode electrodes for proton exchange membrane fuel cells (PEMFCs) with ultra-low platinum loadings as low as 0.012 mg{sub Pt}cm{sup -2} have been prepared by the electrospray method. The electrosprayed layers have nanostructured fractal morphologies with dendrites formed by clusters (about 100 nm diameter) of a few single catalyst particles rendering a large exposure surface of the catalyst. Optimization of the control parameters affecting this morphology has allowed us to overcome the state of the art for efficient electrodes prepared by electrospraying. Thus, using these cathodes in membrane electrode assemblies (MEAs), a high platinum utilization in the range 8-10 kW g{sup -1} was obtained for the fuel cell operating at 40 C and atmospheric pressure. Moreover, a platinum utilization of 20 kW g{sup -1} was attained under more suitable operating conditions (70 C and 3.4 bar over-pressure). These results substantially improve the performances achieved previously with other low platinum loading electrodes prepared by electrospraying. (author)

  4. Excision of pyrimidine dimers from epidermal DNA and nonsemiconservative epidermal DNA synthesis following ultraviolet irradiation of mouse skin

    International Nuclear Information System (INIS)

    Bowden, G.T.; Trosko, J.E.; Shapas, B.G.; Boutwell, R.K.

    1975-01-01

    Pyrimidine dimer production and excision in epidermal DNA were studied at five different dose levels of ultraviolet light in the skin of intact mice. Dimer production increased with dose up to 50,400 ergs/sq mm. Approximately 30 percent of the thymine-containing dimers were excised by 24 hr after irradiation at three lower dose levels of ultraviolet light. Nonsemiconservative DNA replication in ultraviolet-irradiated mouse skin was shown to continue for at least 18 hr. The rate of nonsemiconservative replication decreased with time, but did so slowly. The initial rates of nonsemiconservative replication increased with ultraviolet light dose levels up to about 4200 ergs/sq mm, after which the initial rates were decreased. Semiconservative epidermal DNA synthesis was shown to be inhibited by hydroxyurea, but hydroxyurea had no effect on ultraviolet light-induced nonsemiconservative DNA replication. The observed pyrimidine dimer excision and nonsemiconservative DNA replication suggest that in the intact mouse the cells of the epidermis are capable of DNA excision repair after ultraviolet irradiation of mouse skin

  5. Rapid method for detecting base damage in DNA of mammalian cells: assay of U. V. -induced pyrimidine dimers in human cells

    Energy Technology Data Exchange (ETDEWEB)

    Bryant, P E [Hammersmith Hospital, London (UK). M.R.C. Cyclotron Unit; Jansson, G; Ahnstroem, G

    1978-11-01

    Simple and rapid techniques are described for the detection of pyrimidine dimers in DNA. Human cells derived from embryonic lung tissue were UV-irradiated and subjected to either an osmotic shock procedure or detergent lysis, then treated with UV-endonuclease from Micrococcus luteus and the DNA partially denatured by treatment with weak alkali. Brief sonication reduced the molecular weight of the DNA, and the single- and double-stranded DNA could then be separated by hydroxylapatite chromatography. Approximately 40% of the expected number of pyrimidine dimers were detected by the enzyme treatment technique. The mean value of numbers of strand breaks per 10/sup 9/ dalton per J/m/sup 2/ was approximately 50% of the expected value. The method has advantages of speed and reproducibility and a large reduction in the quantities of materials used, particularly at the scintillation-counting stage.

  6. Enhanced cis-platinum ototoxicity in children with brain tumours who have received simultaneous or prior cranial irradiation

    International Nuclear Information System (INIS)

    Walker, D.A.; Pillow, J.; Waters, K.D.; Keir, E.

    1989-01-01

    We report on four children who received cis-platinum simultaneously with, or in one case 10 months after, cranial irradiation and experienced exaggerated ototoxicity affecting all audible frequencies. The hearing loss was severe, affecting the critical areas for speech perception, and necessitated the provision of bilateral hearing aids. The audiograms of these patients are shown and compared to those of four children who had received cis-platinum as part of their treatment for neuroblastoma but without cranial irradiation. The precipitation of the exaggerated hearing loss with the administration of cis-platinum in one patient 10 months after finishing cranial irradiation suggests that care should be taken in the timing of cis-platinum administration in relation to concurrent or previous cranial irradiation

  7. TEM and EELS studies of microwave-irradiation synthesis of bimetallic platinum nanocatalysts

    International Nuclear Information System (INIS)

    Mathe, N R; Scriba, M R; Coville, N J; Olivier, J E

    2014-01-01

    Microwave-irradiation (MW) synthesis of nanostructured materials provides for the synthesis of metal nanoparticles, using fast and uniform heating rates. This procedure affords better control of the shape and size of the nanoparticles when compared to conventional methods. In this work, microwave-irradiation was used to produce platinum-cobalt (Pt-Co) and platinum-nickel (Pt-Ni) nanoparticles for use as electrocatalysts in the methanol oxidation reaction. High resolution TEM imaging and EELS studies revealed that these bimetallic nanoparticles form islands or hetero-structures

  8. Thiosemicarbazone complexes of the platinum metals. A story of ...

    Indian Academy of Sciences (India)

    Unknown

    Thiosemicarbazone complexes; platinum metals; variable coordination; ... carbonylic carbon via one or two intervening atoms, D,N,S tricoordination usually takes .... modelling studies show that in this coordination mode, the phenyl ring of the.

  9. Ultrasound assisted one pot expeditious synthesis of new pyrido[2,3-d]pyrimidine analogues using mild and inexpensive 4-dimethylaminopyridine (DMAP catalyst

    Directory of Open Access Journals (Sweden)

    Ajmal R. Bhat

    2017-09-01

    Full Text Available The one-pot three-component reaction for the synthesis of pyrido[2,3-d]pyrimidine derivatives has been reported via initial Knoevenagel, subsequent addition and final heterocyclization of substituted aromatic aldehydes, cyanoacetamide and 6-aminouracil in N,N-dimethylformamide (DMF solvent using 4-dimethylaminopyridine (DMAP as new organocatalyst under ultrasound irradiation. The results showed that a series of aromatic aldehydes were successfully used to prepare the targeted pyrido[2,3-d]pyrimidine derivatives with good to excellent yields (81–93% and there is no major effect on the yield of product by electron donating/withdrawing substituents. Short reaction time, environment friendly procedure, excellent yields, inexpensive and readily available catalyst are the advantages of this procedure. All synthesized compounds were characterized by IR, 1HNMR, 13CNMR and mass spectral data.

  10. A bioaccumulative cyclometalated platinum(II) complex with two-photon-induced emission for live cell imaging.

    Science.gov (United States)

    Koo, Chi-Kin; Wong, Ka-Leung; Man, Cornelia Wing-Yin; Lam, Yun-Wah; So, Leo King-Yan; Tam, Hoi-Lam; Tsao, Sai-Wah; Cheah, Kok-Wai; Lau, Kai-Chung; Yang, Yang-Yi; Chen, Jin-Can; Lam, Michael Hon-Wah

    2009-02-02

    The cyclometalated platinum(II) complex [Pt(L)Cl], where HL is a new cyclometalating ligand 2-phenyl-6-(1H-pyrazol-3-yl)pyridine containing C(phenyl), N(pyridyl), and N(pyrazolyl) donor moieties, was found to possess two-photon-induced luminescent properties. The two-photon-absorption cross section of the complex in N,N-dimethylformamide at room temperature was measured to be 20.8 GM. Upon two-photon excitation at 730 nm from a Ti:sapphire laser, bright-green emission was observed. Besides its two-photon-induced luminescent properties, [Pt(L)Cl] was able to be rapidly accumulated in live HeLa and NIH3T3 cells. The two-photon-induced luminescence of the complex was retained after live cell internalization and can be observed by two-photon confocal microscopy. Its bioaccumulation properties enabled time-lapse imaging of the internalization process of the dye into living cells. Cytotoxicity of [Pt(L)Cl] to both tested cell lines was low, according to MTT assays, even at loadings as high as 20 times the dose concentration for imaging for 6 h.

  11. Identification of the formation of metal-vinylidene interfacial bonds of alkyne-capped platinum nanoparticles by isotopic labeling.

    Science.gov (United States)

    Hu, Peiguang; Chen, Limei; Deming, Christopher P; Bonny, Lewis W; Lee, Hsiau-Wei; Chen, Shaowei

    2016-10-07

    Stable platinum nanoparticles were prepared by the self-assembly of 1-dodecyne and dodec-1-deuteroyne onto bare platinum colloid surfaces. The nanoparticles exhibited consistent core size and optical properties. FTIR and NMR measurements confirmed the formation of Pt-vinylidene (Pt[double bond, length as m-dash]C[double bond, length as m-dash]CH-) interfacial linkages rather than Pt-acetylide (Pt-C[triple bond, length as m-dash]C-) and platinum-hydride (Pt-H) bonds.

  12. The influence of nitrate concentrations and acidity on the electrocatalytic reduction of nitrate on platinum

    NARCIS (Netherlands)

    Groot, de M.T.; Koper, M.T.M.

    2004-01-01

    A study was performed to determine the influence of nitrate concentration and acidity on the reaction rate and selectivity of the electrocatalytic nitrate reduction on platinum. There are two different nitrate reduction mechanisms on platinum: a direct mechanism (0.4–0.1 V vs. SHE) and an indirect

  13. GREEN PACKAGING, GREEN PRODUCT, GREEN ADVERTISING, PERSEPSI, DAN MINAT BELI KONSUMEN

    OpenAIRE

    Imam Santoso; Rengganis Fitriani

    2016-01-01

    Environmental problems become one of the strategic issues in achieving global competitiveness. One of the issues is products that are made from environmental friendly materials or known as green product. Furthermore, in green products marketing, the company also uses green packaging and green advertising concept. This study aimed to analyze the effect of green packaging, green products, and green advertising on consumer perception and purchasing intention. The study was conducted in Ketawangg...

  14. Synthesis and antiviral activity of 2,4-diamino-5-cyano-6-[2-(phosphonomethoxy)ethoxy]pyrimidine and related compounds

    Czech Academy of Sciences Publication Activity Database

    Hocková, Dana; Holý, Antonín; Masojídková, Milena; Andrei, G.; Snoeck, R.; De Clercq, E.; Balzarini, J.

    2004-01-01

    Roč. 12, č. 12 (2004), s. 3197-3202 ISSN 0968-0896 R&D Projects: GA AV ČR IBS4055109 Grant - others:ISEP/FORTIS(US) GOA-00/12; European Commission(XE) HPAW-2002-90001 Institutional research plan: CEZ:AV0Z4055905 Keywords : nucleotide analogues * antiviral * pyrimidines Subject RIV: CC - Organic Chemistry Impact factor: 2.018, year: 2004

  15. Crystal structure of 1-ethylpyrazolo[3,4-d]pyrimidine-4(5H-thione

    Directory of Open Access Journals (Sweden)

    Mohammed El Fal

    2014-09-01

    Full Text Available In the title compound, C7H8N4S, the methyl C atom is displaced by 1.232 (7 Å from the mean plane of the pyrazolo[3,4-d]pyrimidine ring system (r.m.s. deviation = 0.007 Å. The N—N—C—Cm (m = methyl torsion angle is −60.3 (6°. In the crystal, molecules are linked by N—H...S hydrogen bonds, generating [010] chains, which are reinforced by C—H...N interactions. The chains are cross-linked by weak C—H...S hydrogen bonds, generating (001 sheets.

  16. Temperature dependence of desoxyribosylation of pyrimidine derivatives labelled with carbon-14 and tritium

    International Nuclear Information System (INIS)

    Pritasil, L.; Filip, J.

    1977-01-01

    The effect of the temperature and concentration of the enzyme preparation from Escherichia coli B on the reaction of pyrimidine bases with 2-desoxy-α-D-riboso-l-phosphate or α-D-riboso-l-phosphate was studied. It was found that at +2 deg C and low enzyme concentration higher yields of nucleosides are obtained than at the commonly used temperature of 37 deg C. The reaction time, however, must be protracted. The prepared [2- 14 C] uridine, 2'-deoxy[2- 14 C] uridine and [2- 14 C] thymidine had a high specific activity and radiochemical purity

  17. Chiral discrimination in platinum anticancer drugs

    Czech Academy of Sciences Publication Activity Database

    Benedetti, M.; Malina, Jaroslav; Kašpárková, Jana; Brabec, Viktor; Natile, G.

    2002-01-01

    Roč. 110, Suppl. 5 (2002), s. 779-782 ISSN 0091-6765 R&D Projects: GA ČR GA301/00/0556; GA ČR GA305/02/1552; GA AV ČR IAA7004805; GA AV ČR IBS5004107; GA MŠk OC D20.001 Institutional research plan: CEZ:AV0Z5004920 Keywords : DNA * platinum * cancer Subject RIV: BO - Biophysics Impact factor: 3.452, year: 2002

  18. Platinum nanoparticles: a non-toxic, effective and thermally stable alternative plasmonic material for cancer therapy and bioengineering.

    Science.gov (United States)

    Samadi, Akbar; Klingberg, Henrik; Jauffred, Liselotte; Kjær, Andreas; Bendix, Poul Martin; Oddershede, Lene B

    2018-05-17

    Absorption of near infrared (NIR) light by metallic nanoparticles can cause extreme heating and is of interest for instance in cancer treatment since NIR light has a relatively large penetration depth into biological tissue. Here, we quantify the extraordinary thermoplasmonic properties of platinum nanoparticles and demonstrate their efficiency in photothermal cancer therapy. Although platinum nanoparticles are extensively used for catalysis, they are much overlooked in a biological context. Via direct measurements based on a biological matrix we show that individual irradiated platinum nanoparticles with diameters of 50-70 nm can easily reach surface temperatures up to 900 K. In contrast to gold nanoshells, which are often used for photothermal purposes, we demonstrate that the platinum particles remain stable at these extreme temperatures. The experiments are paralleled by finite element modeling confirming the experimental results and establishing a theoretical understanding of the particles' thermoplasmonic properties. At extreme temperatures it is likely that a vapor layer will form around the plasmonic particle, and we show this scenario to be consistent with direct measurements and simulations. Viability studies demonstrate that platinum nanoparticles themselves are non-toxic at therapeutically relevant concentrations, however, upon laser irradiation we show that they efficiently kill human cancer cells. Therefore, platinum nanoparticles are highly promising candidates for thermoplasmonic applications in the life sciences, in nano-medicine, and for bio-medical engineering.

  19. Synthesis, Molecular Docking, and Antimycotic Evaluation of Some 3-Acyl Imidazo[1,2-a]pyrimidines

    Directory of Open Access Journals (Sweden)

    Omar Gómez-García

    2018-03-01

    Full Text Available A series of 3-benzoyl imidazo[1,2-a]pyrimidines, obtained from N-heteroarylformamidines in good yields, was tested in silico and in vitro for binding and inhibition of seven Candida species (Candida albicans (ATCC 10231, Candida dubliniensis (CD36, Candida glabrata (CBS138, Candida guilliermondii (ATCC 6260, Candida kefyr, Candida krusei (ATCC 6358 and Candida tropicalis (MYA-3404. To predict binding mode and energy, each compound was docked in the active site of the lanosterol 14α-demethylase enzyme (CYP51, essential for fungal growth of Candida species. Antimycotic activity was evaluated as the 50% minimum inhibitory concentration (MIC50 for the test compounds and two reference drugs, ketoconazole and fluconazole. All test compounds had a better binding energy (range: −6.11 to −9.43 kcal/mol than that found for the reference drugs (range: 48.93 to −6.16 kcal/mol. In general, the test compounds showed greater inhibitory activity of yeast growth than the reference drugs. Compounds 4j and 4f were the most active, indicating an important role in biological activity for the benzene ring with electron-withdrawing substituents. These compounds show the best MIC50 against C. guilliermondii and C. glabrata, respectively. The current findings suggest that the 3-benzoyl imidazo[1,2-a]pyrimidine derivatives, herein synthesized by an accessible methodology, are potential antifungal drugs.

  20. Greens of the European Green Capitals

    Science.gov (United States)

    Cömertler, Seval

    2017-10-01

    Well established and maintained green areas have a key role on reaching the high quality of life and sustainability in urban environments. Therefore, green areas must be carefully accounted and evaluated in the urban planning affairs. In this context, the European Green Capitals, which attach a great importance to the green areas, have a great potential to act as a role model for both small and big cities in all around the world. These leading cities (chronologically, Stockholm, Hamburg, Vitoria-Gasteiz, Nantes, Copenhagen, Bristol, Ljubljana, Essen and Nijmegen) are inspiring for the other cities which seek to achieve more sustainable and environmentally friendly places through green areas. From this point of view, the aim of this paper was to investigate the green areas of the European Green Capitals. The paper covered whole European Green Capitals, and the application form of each Green Capital was used as a primary data source. Consequently, the paper put forwarded that the European Green Capitals have considerably large amount and high proportion of green areas. Further, these cities provide an excellent access to the public green areas. As a result of abundant provision and proper distribution, the almost all citizens in most of the Green Capitals live within a distance of 300 meters to a green area. For further researches, the paper suggested that these green capitals should be investigated in terms of their efforts, measures, goals and plans, policies and implications to administer, to protect, to enhance and to expand the green areas.

  1. In vitro permeation of platinum through African and Caucasian skin.

    Science.gov (United States)

    Franken, A; Eloff, F C; du Plessis, J; Badenhorst, C J; Du Plessis, J L

    2015-02-03

    The majority of the South African workforce are Africans, therefore potential racial differences should be considered in risk and exposure assessments in the workplace. Literature suggests African skin to be a superior barrier against permeation and irritants. Previous in vitro studies on metals only included skin from Caucasian donors, whereas this study compared the permeation of platinum through African and Caucasian skin. A donor solution of 0.3 mg/ml of potassium tetrachloroplatinate (K₂PtCl₄) dissolved in synthetic sweat was applied to the vertical Franz diffusion cells with full thickness abdominal skin. Skin from three female African and three female Caucasian donors were included (n=21). The receptor solution was removed at various intervals during the 24 h experiment, and analysed with high resolution inductively coupled plasma-mass spectrometry (ICP-MS). Skin was digested and analysed by inductively coupled plasma-optical emission spectrometry (ICP-OES). Significantly higher permeation of platinum through intact African skin (p=0.044), as well as a significantly higher mass of platinum retention in African skin in comparison with Caucasian skin (p=0.002) occurred. Significant inter-donor variation was found in both racial groups (pskin and further investigation is necessary to explain the higher permeation through African skin. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  2. Textured strontium titanate layers on platinum by atomic layer deposition

    International Nuclear Information System (INIS)

    Blomberg, T.; Anttila, J.; Haukka, S.; Tuominen, M.; Lukosius, M.; Wenger, Ch.; Saukkonen, T.

    2012-01-01

    Formation of textured strontium titanate (STO) layers with large lateral grain size (0.2–1 μm) and low X-ray reflectivity roughness (∼ 1.36 nm) on Pt electrodes by industry proven atomic layer deposition (ALD) method is demonstrated. Sr(t-Bu 3 Cp) 2 , Ti(OMe) 4 and O 3 precursors at 250 °C were used to deposit Sr rich STO on Pt/Ti/SiO 2 /Si ∅200 mm substrates. After crystallization post deposition annealing at 600 °C in air, most of the STO grains showed a preferential orientation of the {001} plane parallel to the substrate surface, although other orientations were also present. Cross sectional and plan view transmission electron microscopy and electron diffraction analysis revealed more than an order of magnitude larger lateral grain sizes for the STO compared to the underlying multicrystalline {111} oriented platinum electrode. The combination of platinum bottom electrodes with ALD STO(O 3 ) shows a promising path towards the formation of single oriented STO film. - Highlights: ► Amorphous strontium titanate (STO) on platinum formed a textured film after annealing. ► Single crystal domains in 60 nm STO film were 0.2–1 μm wide. ► Most STO grains were {001} oriented.

  3. Nanoparticulate platinum films on gold using dendrimer-based wet ...

    Indian Academy of Sciences (India)

    Central Electrochemical Research Institute, Karaikudi 630 006, India. E-mail: ... deposition methods for applications involving thin films, e.g., catalysis. Deposition of platinum .... The spectrum recorded at 0.3 V shows a mixed control behaviour ...

  4. Copper (II) complexes of bidentate ligands exhibit potent anti-cancer activity regardless of platinum sensitivity status.

    Science.gov (United States)

    Wehbe, Mohamed; Lo, Cody; Leung, Ada W Y; Dragowska, Wieslawa H; Ryan, Gemma M; Bally, Marcel B

    2017-12-01

    Insensitivity to platinum, either through inherent or acquired resistance, is a major clinical problem in the treatment of many solid tumors. Here, we explored the therapeutic potential of diethyldithiocarbamate (DDC), pyrithione (Pyr), plumbagin (Plum), 8-hydroxyquinoline (8-HQ), clioquinol (CQ) copper complexes in a panel of cancer cell lines that differ in their sensitivity to platins (cisplatin/carboplatin) using a high-content imaging system. Our data suggest that the copper complexes were effective against both platinum sensitive (IC 50  ~ 1 μM platinum) and insensitive (IC 50  > 5 μM platinum) cell lines. Furthermore, copper complexes of DDC, Pyr and 8-HQ had greater therapeutic activity compared to the copper-free ligands in all cell lines; whereas the copper-dependent activities of Plum and CQ were cell-line specific. Four of the copper complexes (Cu(DDC) 2 , Cu(Pyr) 2 , Cu(Plum) 2 and Cu(8-HQ) 2 ) showed IC 50 values less than that of cisplatin in all tested cell lines. The complex copper DDC (Cu(DDC) 2 ) was selected for in vivo evaluation due to its low nano-molar range activity in vitro and the availability of an injectable liposomal formulation. Liposomal (Cu(DDC) 2 ) was tested in a fast-growing platinum-resistant A2780-CP ovarian xenograft model and was found to achieve a statistically significant reduction (50%; p < 0.05) in tumour size. This work supports the potential use of copper-based therapeutics to treat cancers that are insensitive to platinum drugs.

  5. Platinum Jubilee of the Indian Academy of Science

    Indian Academy of Sciences (India)

    user

    Platinum Jubilee of the Indian Academy of Science βγ-Crystallins and the bacterial immunoglobulines fold: Two calcium binding folds. Yogendra Sharma. Centre for Cellular and Molecular Biology (CCMB). "Hell is a half-filled auditorium ". Hell is a half-filled auditorium. - Robert Frost (1874-1963) ...

  6. Release of low molecular weight silicones and platinum from silicone breast implants.

    Science.gov (United States)

    Lykissa, E D; Kala, S V; Hurley, J B; Lebovitz, R M

    1997-12-01

    We have conducted a series of studies addressing the chemical composition of silicone gels from breast implants as well as the diffusion of low molecular weight silicones (LM-silicones) and heavy metals from intact implants into various surrounding media, namely, lipid-rich medium (soy oil), aqueous tissue culture medium (modified Dulbecco's medium, DMEM), or an emulsion consisting of DMEM plus 10% soy oil. LM-silicones in both implants and surrounding media were detected and quantitated using gas chromatography (GC) coupled with atomic emission (GC-AED) as well as mass spectrometric (GC/MS) detectors, which can detect silicones in the nanogram range. Platinum, a catalyst used in the preparation of silicone gels, was detected and quantitated using inductive argon-coupled plasma/mass spectrometry (ICP-MS), which can detect platinum in the parts per trillion range. Our results indicate that GC-detectable low molecular weight silicones contribute approximately 1-2% to the total gel mass and consist predominantly of cyclic and linear poly-(dimethylsiloxanes) ranging from 3 to 20 siloxane [(CH3)2-Si-O] units (molecular weight 200-1500). Platinum can be detected in implant gels at levels of approximately 700 micrograms/kg by ICP-MS. The major component of implant gels appears to be high molecular weight silicone polymers (HM-silicones) too large to be detected by GC. However, these HM-silicones can be converted almost quantitatively (80% by mass) to LM-silicones by heating implant gels at 150-180 degrees C for several hours. We also studied the rates at which LM-silicones and platinum leak through the intact implant outer shell into the surrounding media under a variety of conditions. Leakage of silicones was greatest when the surrounding medium was lipid-rich, and up to 10 mg/day LM-silicones was observed to diffuse into a lipid-rich medium per 250 g of implant at 37 degrees C. This rate of leakage was maintained over a 7-day experimental period. Similarly, platinum was

  7. Platinum Monolayer Electrocatalysts for Anodic Oxidation of Alcohols.

    Science.gov (United States)

    Li, Meng; Liu, Ping; Adzic, Radoslav R

    2012-12-06

    The slow, incomplete oxidation of methanol and ethanol on platinum-based anodes as well as the high price and limited reserves of Pt has hampered the practical application of direct alcohol fuel cells. We describe the electrocatalysts consisting of one Pt monolayer (one atom thick layer) placed on extended or nanoparticle surfaces having the activity and selectivity for the oxidation of alcohol molecules that can be controlled with platinum-support interaction. The suitably expanded Pt monolayer (i.e., Pt/Au(111)) exhibits a factor of 7 activity increase in catalyzing methanol electrooxidation relative to Pt(111). Sizable enhancement is also observed for ethanol electrooxidation. Furthermore, a correlation between substrate-induced lateral strain in a Pt monolayer and its activity/selectivity is established and rationalized by experimental and theoretical studies. The knowledge we gained with single-crystal model catalysts was successfully applied in designing real nanocatalysts. These findings for alcohols are likely to be applicable for the oxidation of other classes of organic molecules.

  8. Synthesis and In Vitro Inhibition Effect of New Pyrido[2,3-d]pyrimidine Derivatives on Erythrocyte Carbonic Anhydrase I and II

    Directory of Open Access Journals (Sweden)

    Hilal Kuday

    2014-01-01

    Full Text Available In vitro inhibition effects of indolylchalcones and new pyrido[2,3-d]pyrimidine derivatives on purified human carbonic anhydrase I and II (hCA I and II were investigated by using CO2 as a substrate. The results showed that all compounds inhibited the hCA I and hCA II enzyme activities. Among all the synthesized compounds, 7e (IC50=6.79 µM was found to be the most active compound for hCA I inhibitory activity and 5g (IC50=7.22 µM showed the highest hCA II inhibitory activity. Structure-activity relationships study showed that indolylchalcone derivatives have higher inhibitory activities than pyrido[2,3-d]pyrimidine derivatives on hCA I and hCA II. Additionally, methyl group bonded to uracil ring increases inhibitory activities on both hCA I and hCA II.

  9. A retrospective evaluation of activity of gemcitabine/platinum regimens in the treatment of recurrent ovarian cancer

    Directory of Open Access Journals (Sweden)

    Tran N. Le

    2017-11-01

    Full Text Available Abstract Background While many of these agents have been compared in prospective clinical trials, the gemcitabine/platinumbased regimens have not been compared in a prospective, randomized clinical trial. While bothgemcitabine/carboplatin and gemcitabine/cisplatin have a similar ORR in separate clinical trials, the tworegimens have never been directly been compared. With overlapping dose-limiting toxicity of thrombocytopenia, the gemcitabine/carboplatin regimen has been challenging to employ in the clinical setting in previously treated ovarian cancer patients and is often associated with treatment delays and/or dose reductions. Gemcitabine/cisplatin can also be a challenge due to its dose limiting neuropathy and renal toxicity, especially in previously treated patients. In the absence of any prospective, head to head comparison this retrospective study was embarked upon to compare the response rate and toxicity profiles of gemcitabine/cisplatin verses gemcitabine/carboplatin for the treatment of platinum-sensitive verses platinum-resistant recurrent ovarian cancer. Methods This was a retrospective chart review study that identified patients that had received either gemcitabine/cisplatin or gemcitabine/carboplatin for treatment of recurrent ovarian cancer and compared documented hematological and non-hematological toxicity and response based on RECIST (v1.1. Data was evaluated based upon platinum sensitivity/resistance as well. Results A total of 93 patients were identified that had received a gemcitabine/platinum regimen with 48 with recurrent ovarian cancer that were included in the study. There were 21 patients in the gemcitabine/cisplatin arm and 27 patients identified in the gemcitabine/carboplatin arm. Objective response rate (ORR was greater in platinum-sensitive patients that received gemcitabine/carboplatin compared to gemcitabine/cisplatin (8 (67% vs 2 (25%, p < 0.05. Conversely, ORR was greater in platinum-resistant patients treated

  10. Comprehensive analysis of pyrimidine metabolism in 450 children with unspecific neurological symptoms using high-pressure liquid chromatography-electrospray ionization tandem mass spectrometry.

    Science.gov (United States)

    Schmidt, C; Hofmann, U; Kohlmüller, D; Mürdter, T; Zanger, U M; Schwab, M; Hoffmann, G F

    2005-01-01

    To evaluate the significance of inborn metabolic disorders of the pyrimidine degradation pathway, 450 children with unspecific neurological symptoms were comprehensively studied; 200 healthy children were recruited as controls. Uracil and thymine as well as their degradation products in urine were determined with an improved method based on reversed-phase HPLC coupled with electrospray ionization tandem mass spectrometry and detection by multiple-reaction monitoring using stable-isotope-labelled reference compounds as internal standards. From the results of the control group we established age-related reference ranges of all pyrimidine degradation products. In the patient group, two children with dihydropyrimidine dehydrogenase (DPYD) deficiency were identified; one of these was homozygous for the exon 14-skipping mutation of the DPYD gene. In addition, two patients with high uracil, dihydrouracil and beta-ureidopropionate were found to have ornithine transcarbamylase deficiency. In the urine of 9 patients, beta-alanine was markedly elevated owing to treatment with vigabatrin, an irreversible inhibitor of GABA transaminase, which interferes with beta-alanine breakdown. Four patients had exclusively high levels of beta-aminoisobutyrate (beta-AIB) due to a low activity of the D-beta-AIB-pyruvate aminotransferase, probably without clinical significance. In conclusion, quantitative investigation of pyrimidine metabolites in children with unexplained neurological symptoms, particularly epileptic seizures with or without psychomotor retardation, can be recommended as a helpful tool for diagnosis in clinical practice. Sensitive methods and age-related reference ranges enable the detection of partial enzyme deficiencies.

  11. From green architecture to architectural green

    DEFF Research Database (Denmark)

    Earon, Ofri

    2011-01-01

    that describes the architectural exclusivity of this particular architecture genre. The adjective green expresses architectural qualities differentiating green architecture from none-green architecture. Currently, adding trees and vegetation to the building’s facade is the main architectural characteristics...... they have overshadowed the architectural potential of green architecture. The paper questions how a green space should perform, look like and function. Two examples are chosen to demonstrate thorough integrations between green and space. The examples are public buildings categorized as pavilions. One......The paper investigates the topic of green architecture from an architectural point of view and not an energy point of view. The purpose of the paper is to establish a debate about the architectural language and spatial characteristics of green architecture. In this light, green becomes an adjective...

  12. Synthesis and characterization of platinum supported on alumina doped with cerium catalyst

    International Nuclear Information System (INIS)

    Yusof Abdullah; Abd Fatah Awang Mat; Mohd Ali Sufi; Sarimah Mahat; Razali Kassim; Nurhaslinda Abdullah.

    1996-03-01

    The synthesis and characterization of gamma-alumina doped with cerium as platinum support for the automobile exhaust catalyst are described. Platinum/alumina/ceria catalyst were prepared by impregnation of hexachloroplatinic acid and sintered at 500 degree Celsius to obtain metal dispersions of 1.0 wt%. Catalyst distribution inside the powder and the effects of the addition of cerium to alumina were analyzed by the scanning electron microscopy (SEM) and x-ray fluorescence spectroscopy (XRF). The results showed that the alumina - supported catalysts contained well dispersion of the noble metal

  13. Wireless gas sensing in South African underground platinum mines

    CSIR Research Space (South Africa)

    Abu-Mahfouz, Adnan M

    2014-04-01

    Full Text Available Approximately 70% of South African mines are classified as fiery, where methane gas potentially could cause explosions. The number of flammable gas reports and accidents are increasing steadily for both gold and platinum mines. However...

  14. Study of hydrogen mobility by hydrogen-deuterium exchange. II. Theoretical kinetic study in alkyl and amino-alkyl pyrimidines

    International Nuclear Information System (INIS)

    Pompon, Alain

    1975-01-01

    Alkyl groups bound to the pyrimidine ring can be deuterium substituted on the carbon adjacent to the ring, in acidic D 2 O; kinetic equations corresponding to various exchange mechanism hypothesis are established. It is shown that theoretical and experimental results can be compared in order to precise the mechanism and to measure the characteristic parameters of the exchange reaction [fr

  15. Synthesis and antibacterial activity of some derivatives of 1,3,4-thia-dia-zol[3,2-a]pyrimidine

    International Nuclear Information System (INIS)

    Sangov, Z.G.

    2004-01-01

    The purpose of this work is direct synthesis of derivatives of 1,3,4-thia-dia-zol[3,2-a]pyrimidine containing functional groups in second and sixth position of cycle, studying antibacterial activity obtained compounds on culture fungus, typical for this region and searching for new high-effective biologically active matters with low toxicity which let wide assortment of medicinal preparations

  16. A phase 2, open-label, multi-center study of amuvatinib in combination with platinum etoposide chemotherapy in platinum-refractory small cell lung cancer patients.

    Science.gov (United States)

    Byers, Lauren Averett; Horn, Leora; Ghandi, Jitendra; Kloecker, Goetz; Owonikoko, Taofeek; Waqar, Saiama Naheed; Krzakowski, Maciej; Cardnell, Robert J; Fujimoto, Junya; Taverna, Pietro; Azab, Mohammad; Camidge, David Ross

    2017-10-06

    Amuvatinib (MP-470) is a multi-targeted kinase inhibitor with potent activity against c-Kit, synergistic with DNA-damaging agents. We evaluated amuvatinib in combination with platinum-etoposide (EP) chemotherapy by objective response rate, survival, and tolerability in platinum-refractory small cell lung cancer (SCLC) patients. This study used a Simon 2-stage design requiring ≥3 centrally confirmed responses in the first 21 subjects. Subjects received EP with 300 mg amuvatinib orally three times daily in cycles of 21 days. A three-day amuvatinib run-in period before EP occurred in Cycle 1. Subjects received the same EP chemotherapy regimen given prior to progression/relapse. Among 23 subjects treated, we observed four PRs (17.4%) per RECIST 1.1, only two of which were centrally confirmed (8.7%, response duration 119, 151 days). Three subjects (13%) had confirmed stable disease. c-Kit H-score was ≥100 in two subjects whose respective durations of disease control were 151 and 256 days. The addition of amuvatinib to EP chemotherapy in unselected, platinum-refractory SCLC did not meet the primary endpoint of ≥3 confirmed responses in stage 1. However, high c-Kit expression in two subjects with durable disease control suggests the potential for further study of amuvatinib in SCLC patients with high c-Kit expression.

  17. Determinants of ototoxicity in 451 platinum-treated Dutch survivors of childhood cancer : A DCOG late-effects study

    NARCIS (Netherlands)

    Clemens, Eva; de Vries, Andrica C.; Pluijm, Saskia F.; Zehnhoff-Dinnesen, Antoinette Am; Tissing, Wim J.; Loonen, Jacqueline J.; van Dulmen-den Broeder, Eline; Bresters, Dorine; Versluys, Birgitta; Kremer, Leontien C.; van der Pal, Heleen J.; van Grotel, Martine; van den Heuvel-Eibrink, Marry M.

    2016-01-01

    Platinum-containing chemotherapeutics are efficacious for a variety of pediatric malignancies, nevertheless these drugs can induce ototoxicity. However, ototoxicity data on large cohorts of childhood cancer survivors (CCSs) who received platinum agents, but not cranial irradiation are scarce.

  18. Nanofiber-deposited porous platinum enables glucose fuel cell anodes with high current density in body fluids

    Science.gov (United States)

    Frei, Maxi; Erben, Johannes; Martin, Julian; Zengerle, Roland; Kerzenmacher, Sven

    2017-09-01

    The poisoning of platinum anodes by body-fluid constituents such as amino acids is currently the main hurdle preventing the application of abiotic glucose fuel cells as battery-independent power supply for medical implants. We present a novel anode material that enables continuous operation of glucose oxidation anodes in horse serum for at least 30 days at a current density of (7.2 ± 1.9) μA cm-2. The fabrication process is based on the electro-deposition of highly porous platinum onto a 3-dimensional carbon nanofiber support, leading to approximately 2-fold increased electrode roughness factors (up to 16500 ± 2300). The material's superior performance is not only related to its high specific surface area, but also to an improved catalytic activity and/or poisoning resistance. Presumably, this results from the micro- and nanostructure of the platinum deposits. This represents a major step forward in the development of implantable glucose fuel cells based on long-term stable platinum electrodes.

  19. Ruthenium-platinum bimetallic catalysts supported on silica: characterization and study of benzene hydrogenation and CO methanation

    Energy Technology Data Exchange (ETDEWEB)

    Chakrabarty, D.K.; Rao, K.M.; Sundararaman, N.; Chandavar, K.

    1986-12-15

    Ru-Pt/SiO/sub 2/ bimetallic catalysts with varying Ru:Pt ratio have been prepared and studied with the aim to establish if they contain coclusters or isolated ruthenium and platinum particles. X-ray diffraction studies show that individual crystallites of ruthenium and platinum are present and no coclusters are formed. Metal dispersion has been determined by hydrogen chemisorption and surface composition of the catalysts has been obtained from XPS. It was found that preoxidation of the catalysts prior to reduction is essential for good platinum dispersion. The experimental turnover number (TN) for benzene hydrogenation on the bimetallic catalysts agrees very well with that of the weighted average on the individual metal catalysts and this may be taken as a kinetic evidence for the absence of coclusters. Carbon monoxide methanation activity of the bimetallic catalysts is quite similar to that of the supported platinum catalyst. 6 refs., 6 figs., 2 tabs.

  20. Evaluation of the antitumor activity of platinum nanoparticles in the treatment of hepatocellular carcinoma induced in rats.

    Science.gov (United States)

    Medhat, Amina; Mansour, Somaya; El-Sonbaty, Sawsan; Kandil, Eman; Mahmoud, Mustafa

    2017-07-01

    This study aimed to evaluate the antitumor activity of platinum nanoparticles compared with cis-platin both in vitro and in vivo in the treatment of hepatocellular carcinoma induced in rats. The treatment efficacy of platinum nanoparticles was evaluated by measuring antioxidant activities against oxidative stress caused by diethylnitrosamine in liver tissue. The measurements included reduced glutathione content and superoxide dismutase activity, as well as malondialdehyde level. Liver function tests were also determined, in addition to the evaluation of serum alpha-fetoprotein, caspase-3, and cytochrome c in liver tissue. Total RNA extraction from liver tissue samples was also done for the relative quantification of B-cell lymphoma 2, matrix metallopeptidase 9, and tumor protein p53 genes. Histopathological examination was also performed for liver tissue. Results showed that platinum nanoparticles are more potent than cis-platin in treatment of hepatocellular carcinoma induced by diethylnitrosamine in rats as it ameliorated the investigated parameters toward normal control animals. These findings were well appreciated with histopathological studies of diethylnitrosamine group treated with platinum nanoparticles, suggesting that platinum nanoparticles can serve as a good therapeutic agent for the treatment of hepatocellular carcinoma which should attract further studies.

  1. PKC-alpha modulation by miR-483-3p in platinum-resistant ovarian carcinoma cells

    Energy Technology Data Exchange (ETDEWEB)

    Arrighetti, Noemi, E-mail: Noemi.Arrighetti@istitutotumori.mi.it [Molecular Pharmacology Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, via Amadeo 42, Milan 20133 (Italy); Cossa, Giacomo, E-mail: Gia.Cossa@gmail.com [Molecular Pharmacology Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, via Amadeo 42, Milan 20133 (Italy); De Cecco, Loris, E-mail: Loris.Dececco@istitutotumori.mi.it [Functional Genomics and Bioinformatics, Fondazione IRCCS Istituto Nazionale dei Tumori, via Amadeo 42, Milan 20133 (Italy); Stucchi, Simone, E-mail: Simone.Stucchi@istitutotumori.mi.it [Molecular Pharmacology Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, via Amadeo 42, Milan 20133 (Italy); Carenini, Nives, E-mail: Nives.Carenini@istitutotumori.mi.it [Molecular Pharmacology Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, via Amadeo 42, Milan 20133 (Italy); Corna, Elisabetta, E-mail: Elisabetta.Corna@istitutotumori.mi.it [Molecular Pharmacology Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, via Amadeo 42, Milan 20133 (Italy); Gandellini, Paolo, E-mail: Paolo.Gandellini@istitutotumori.mi.it [Molecular Pharmacology Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, via Amadeo 42, Milan 20133 (Italy); Zaffaroni, Nadia, E-mail: Nadia.Zaffaroni@istitutotumori.mi.it [Molecular Pharmacology Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, via Amadeo 42, Milan 20133 (Italy); Perego, Paola, E-mail: paola.perego@istitutotumori.mi.it [Molecular Pharmacology Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, via Amadeo 42, Milan 20133 (Italy); Gatti, Laura, E-mail: Laura.Gatti@istitutotumori.mi.it [Molecular Pharmacology Unit, Fondazione IRCCS Istituto Nazionale dei Tumori, via Amadeo 42, Milan 20133 (Italy)

    2016-11-01

    The occurrence of drug resistance limits the efficacy of platinum compounds in the cure of ovarian carcinoma. Since microRNAs (miRNAs) may contribute to this phenomenon by regulating different aspects of tumor cell response, the aim of this study was to exploit the analysis of expression of miRNAs in platinum sensitive/resistant cells in an attempt to identify potential regulators of drug response. MiR-483-3p, which may participate in apoptosis and cell proliferation regulation, was found up-regulated in 4 platinum resistant variants, particularly in the IGROV-1/Pt1 subline, versus parental cells. Transfection of a synthetic precursor of miR-483-3p in IGROV-1 parental cells elicited a marked up-regulation of the miRNA levels. Growth-inhibition and colony-forming assays indicated that miR-483-3p over-expression reduced cell growth and conferred mild levels of cisplatin resistance in IGROV-1 cells, by interference with their proliferative potential. Predicted targets of miR-483-3p included PRKCA (encoding PKC-alpha), previously reported to be associated to platinum-resistance in ovarian carcinoma. We found that miR-483-3p directly targeted PRKCA in IGROV-1 cells. In keeping with this finding, cisplatin sensitivity of IGROV-1 cells decreased upon molecular/pharmacological inhibition of PKC-alpha. Overall, our results suggest that overexpression of miR-483-3p by ovarian carcinoma platinum-resistant cells may interfere with their proliferation, thus protecting them from DNA damage induced by platinum compounds and ultimately representing a drug-resistance mechanism. The impairment of cell growth may account for low levels of drug resistance that could be relevant in the clinical setting. - Highlights: • miR-483-3p is up-regulated in ovarian carcinoma cells resistant to platinum drugs. • Ectopic expression of miR-483-3p in IGROV-1 confers mild levels of Pt-resistance. • Overexpression of miR-483-3p down-regulates PRKCA levels in ovarian carcinoma cells. • miR 483

  2. The Influence of Proactive Green Innovation and Reactive Green Innovation on Green Product Development Performance: The Mediation Role of Green Creativity

    Directory of Open Access Journals (Sweden)

    Yu-Shan Chen

    2016-09-01

    Full Text Available This study fills the research gap in the exploration of the relationships between both proactive and reactive green innovations and green product development performance, and examines the mediating effect of green creativity. Structural equation modeling (SEM is utilized to test the hypotheses. From the sample of 146 valid respondents, the results show that proactive green innovation positively affects green creativity and green product development performance, and green creativity positively affects green product development performance. In addition, our findings also indicate that the relationship between proactive green innovation and green product development performance is partially mediated by green creativity. Accordingly, green creativity plays a critical role for companies to achieve a great green product development performance. However, reactive green innovation does not significantly influence green creativity and green product development performance. Companies should develop proactive green innovation rather than reactive green innovation in order to enhance their green creativity and increase their product development performance.

  3. Growth mechanism of graphene on platinum: Surface catalysis and carbon segregation

    International Nuclear Information System (INIS)

    Sun, Jie; Lindvall, Niclas; Yurgens, August; Nam, Youngwoo; Cole, Matthew T.; Teo, Kenneth B. K.; Woo Park, Yung

    2014-01-01

    A model of the graphene growth mechanism of chemical vapor deposition on platinum is proposed and verified by experiments. Surface catalysis and carbon segregation occur, respectively, at high and low temperatures in the process, representing the so-called balance and segregation regimes. Catalysis leads to self-limiting formation of large area monolayer graphene, whereas segregation results in multilayers, which evidently “grow from below.” By controlling kinetic factors, dominantly monolayer graphene whose high quality has been confirmed by quantum Hall measurement can be deposited on platinum with hydrogen-rich environment, quench cooling, tiny but continuous methane flow and about 1000 °C growth temperature

  4. Pyrimidine-5'-nucleotidase Campinas, a new mutation (p.R56G) in the NT5C3 gene associated with pyrimidine-5'-nucleotidase type I deficiency and influence of Gilbert's Syndrome on clinical expression.

    Science.gov (United States)

    Santos, Andrey dos; Dantas, Larissa Elizabeth Cordeiro; Traina, Fabiola; Albuquerque, Dulcineia Martins de; Chaim, Elinton Adami; Saad, Sara T Olalla

    2014-12-01

    Pyrimidine-5'-nucleotidase type I (P5'NI) deficiency is an autosomal recessive condition that causes nonspherocytic hemolytic anemia, characterized by marked basophilic stippling and pyrimidine nucleotide accumulation in erythrocytes. We herein present two African descendant patients, father and daughter, with P5'N deficiency, both born from first cousins. Investigation of the promoter polymorphism of the uridine diphospho glucuronosyl transferase 1A (UGT1A) gene revealed that the father was homozygous for the allele (TA7) and the daughter heterozygous (TA6/TA7). P5'NI gene (NT5C3) gene sequencing revealed a further change in homozygosity at amino acid position 56 (p.R56G), located in a highly conserved region. Both patients developed gallstones; however the father, who had undergone surgery for the removal of stones, had extremely severe intrahepatic cholestasis and, liver biopsy revealed fibrosis and siderosis grade III, leading us to believe that the homozygosity of the UGT1A polymorphism was responsible for the more severe clinical features in the father. Moreover, our results show how the clinical expression of hemolytic anemia is influenced by epistatic factors and we describe a new mutation in the P5'N gene associated with enzyme deficiency, iron overload, and severe gallstone formation. To our knowledge, this is the first description of P5'N deficiency in South Americans. Copyright © 2014 Elsevier Inc. All rights reserved.

  5. The levels of disclosure relating to mine closure obligations by platinum mining companies

    Directory of Open Access Journals (Sweden)

    Joline Sturdy

    2017-06-01

    Aim: The aim of this study is to establish the extent to which platinum mines listed on the Johannesburg Stock Exchange (JSE comply with a recommended disclosure framework. Setting: South Africa is the largest producer of platinum in the world. The study covers all platinum mines listed on the JSE. Methods: Using a framework, a census of the annual financial statements, integrated annual reports and sustainability reports or websites was conducted to determine the level of compliance of disclosure relating to mine closure obligations to the recommended disclosure framework. Results: The results show disclosure relating to mine closure obligations of platinum mines listed on the JSE is inconsistent and not sufficient for stakeholders to understand the scope, key assumptions, parameters or reliability of the assessment and calculation of mine closure obligations. Conclusion: The assumptions used to determine mine closure obligations are specialised and multi-disciplinary. The accuracy and reliability of mine closure obligations will improve dramatically through greater transparency and access to information. It is recommended that the JSE listings for mining companies should require a competent person’s report to provide disclosure on assumptions, key values and processes applied to determine the mine closure obligations. Furthermore, it is recommended that the Department of Mineral Resources implements a mechanism of independent assessment of mine closure obligations by experts on an ongoing basis.

  6. One pyrimidine dimer inactivates expression of a transfected gene in xeroderma pigmentosum cells

    International Nuclear Information System (INIS)

    Protic-Sabljic, M.; Kraemer, K.H.

    1985-01-01

    The authors have developed a host cell reactivation assay of DNA repair utilizing UV-treated plasmid vectors. The assay primarily reflects cellular repair of transcriptional activity of damaged DNA measured indirectly as enzyme activity of the transfected genes. They studied three plasmids (pSV2cat, 5020 base pairs; pSV2catSVgpt, 7268 base pairs; and pRSVcat, 5027 base pairs) with different sizes and promoters carrying the bacterial cat gene (CAT, chloramphenicol acetyltransferase) in a construction that permits cat expression in human cells. All human simian virus 40-transformed cells studied expressed high levels of the transfected cat gene. UV treatment of the plasmids prior to transfection resulted in differential decrease in CAT activity in different cell lines. With pSV2catSVgpt, UV inactivation of CAT expression was greater in the xeroderma pigmentosum group A and D lines than in the other human cell lines tested. The D 0 of the CAT inactivation curve was 50 J X m-2 for pSV2cat and for pRSVcat in the xeroderma pigmentosum group A cells. The similarity of the D0 data in the xeroderma pigmentosum group A cells for three plasmids of different size and promoters implies they all have similar UV-inactivation target size. UV-induced pyrimidine dimer formation in the plasmids was quantified by assay of the number of UV-induced T4 endonuclease V-sensitive sites. In the most sensitive xeroderma pigmentosum cells, with all three plasmids, one UV-induced pyrimidine dimer inactivates a target of about 2 kilobases, close to the size of the putative CAT mRNA

  7. Pengaruh Green Marketing Hotel Terhadap Green Consumer Behavior

    OpenAIRE

    Yo Fernandez, Eunike Christe; Tjoanda, Evelyn

    2017-01-01

    Penelitian ini dilakukan untuk mengetahui pengaruh dari green marketing hotel terhadap green consumer behavior. Green marketing memiliki 3 dimensi, yaitu green product, green price, dan green promotion. Penelitian ini melibatkan 272 responden masyarakat Surabaya dan menggunakan metode regresi linear berganda. Hasil penelitian menunjukkan bahwa green product dan green price berpengaruh secara positif dan signifikan sedangkan green promotion berpengaruh namun tidak signifikan terhadap green con...

  8. Platinum-group elements in the Eastern Deccan volcanic province ...

    Indian Academy of Sciences (India)

    This study is the first detailed investigation of the platinum-group elements (PGE) at the eastern mar- ... A Zr vs. Pd scattergram found a strong positive correlation for these two elements ..... and the PGE and Au collected by co-precipitation.

  9. Mechanical polishing as an improved surface treatment for platinum screen-printed electrodes

    Directory of Open Access Journals (Sweden)

    Junqiao Lee

    2016-07-01

    Full Text Available The viability of mechanical polishing as a surface pre-treatment method for commercially available platinum screen-printed electrodes (SPEs was investigated and compared to a range of other pre-treatment methods (UV-Ozone treatment, soaking in N,N-dimethylformamide, soaking and anodizing in aqueous NaOH solution, and ultrasonication in tetrahydrofuran. Conventional electrochemical activation of platinum SPEs in 0.5 M H2SO4 solution was ineffective for the removal of contaminants found to be passivating the screen-printed surfaces. However, mechanical polishing showed a significant improvement in hydrogen adsorption and in electrochemically active surface areas (probed by two different redox couples due to the effective removal of surface contaminants. Results are also presented that suggest that SPEs are highly susceptible to degradation by strong acidic or caustic solutions, and could potentially lead to instability in long-term applications due to continual etching of the binding materials. The ability of SPEs to be polished effectively extends the reusability of these traditionally “single-use” devices. Keywords: Screen-printed electrodes, Polishing, Platinum, Activation, Pre-treatment, Cyclic voltammetry

  10. Repair of pyrimidine dimers in nuclear and mitochondrial DNA of yeast irradiated with low doses of ultraviolet light

    Energy Technology Data Exchange (ETDEWEB)

    Prakash, L [Rochester Univ., N.Y. (USA). Dept. of Radiation Biology and Biophysics

    1975-01-01

    The repair of damage induced by ultraviolet light has been examined in both the nuclear and mitochondrial DNA of the yeast Saccharomyces cerevisiae. The sensitive assay used in this study is based on the capacity of the bacteriophage T4 u.v. endonuclease to produce single-strand breaks in DNA that contains pyrimidine dimers, thus permitting the use of low fluences (doses) of u.v. The results demonstrate that virtually all of the dimers induced in the nuclear DNA of a repair-proficient strain (RAD+) are removed following dark incubation for four hours in growth medium. In contrast, the dimers induced in mitochondrial DNA by the same u.v. fluence are retained under the same conditions. In the excision-deficient mutant, rad1-2, no evidence was obtained for removal of pyrimidine dimers from nuclear DNA. Photoreactivation of both RAD + and rad1-2 cultures resulted in decreases of dimers from both nuclear and mitochondrial DNA. It is concluded that an excision-repair mechanism operates on nuclear but not mitochondrial DNA in repair-proficient yeast, and that the rad1-2 mutant is defective in this process.

  11. Biological Recovery of Platinum Complexes from Diluted Aqueous Streams by Axenic Cultures.

    Directory of Open Access Journals (Sweden)

    Synthia Maes

    Full Text Available The widespread use of platinum in high-tech and catalytic applications has led to the production of diverse Pt loaded wastewaters. Effective recovery strategies are needed for the treatment of low concentrated waste streams to prevent pollution and to stimulate recovery of this precious resource. The biological recovery of five common environmental Pt-complexes was studied under acidic conditions; the chloro-complexes PtCl42- and PtCl62-, the amine-complex Pt(NH34Cl2 and the pharmaceutical complexes cisplatin and carboplatin. Five bacterial species were screened on their platinum recovery potential; the Gram-negative species Shewanella oneidensis MR-1, Cupriavidus metallidurans CH34, Geobacter metallireducens, and Pseudomonas stutzeri, and the Gram-positive species Bacillus toyonensis. Overall, PtCl42- and PtCl62- were completely recovered by all bacterial species while only S. oneidensis and C. metallidurans were able to recover cisplatin quantitatively (99%, all in the presence of H2 as electron donor at pH 2. Carboplatin was only partly recovered (max. 25% at pH 7, whereas no recovery was observed in the case of the Pt-tetraamine complex. Transmission electron microscopy (TEM revealed the presence of both intra- and extracellular platinum particles. Flow cytometry based microbial viability assessment demonstrated the decrease in number of intact bacterial cells during platinum reduction and indicated C. metallidurans to be the most resistant species. This study showed the effective and complete biological recovery of three common Pt-complexes, and estimated the fate and transport of the Pt-complexes in wastewater treatment plants and the natural environment.

  12. DNA interaction with platinum-based cytostatics revealed by DNA sequencing.

    Science.gov (United States)

    Smerkova, Kristyna; Vaculovic, Tomas; Vaculovicova, Marketa; Kynicky, Jindrich; Brtnicky, Martin; Eckschlager, Tomas; Stiborova, Marie; Hubalek, Jaromir; Adam, Vojtech

    2017-12-15

    The main mechanism of action of platinum-based cytostatic drugs - cisplatin, oxaliplatin and carboplatin - is the formation of DNA cross-links, which restricts the transcription due to the disability of DNA to enter the active site of the polymerase. The polymerase chain reaction (PCR) was employed as a simplified model of the amplification process in the cell nucleus. PCR with fluorescently labelled dideoxynucleotides commonly employed for DNA sequencing was used to monitor the effect of platinum-based cytostatics on DNA in terms of decrease in labeling efficiency dependent on a presence of the DNA-drug cross-link. It was found that significantly different amounts of the drugs - cisplatin (0.21 μg/mL), oxaliplatin (5.23 μg/mL), and carboplatin (71.11 μg/mL) - were required to cause the same quenching effect (50%) on the fluorescent labelling of 50 μg/mL of DNA. Moreover, it was found that even though the amounts of the drugs was applied to the reaction mixture differing by several orders of magnitude, the amount of incorporated platinum, quantified by inductively coupled plasma mass spectrometry, was in all cases at the level of tenths of μg per 5 μg of DNA. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Nano carbon supported platinum catalyst interaction behavior with perfluorosulfonic acid ionomer and their interface structures

    DEFF Research Database (Denmark)

    Andersen, Shuang Ma

    2016-01-01

    behavior of Nafion ionomer on platinized carbon nano fibers (CNFs), carbon nano tubes (CNTs) and amorphous carbon (Vulcan). The interaction is affected by the catalyst surface oxygen groups as well as porosity. Comparisons between the carbon supports and platinized equivalents are carried out. It reveals......The interaction between perfluorosulfonic acid ionomer and supported platinum catalyst is essential. It directly influences platinum accessibility, stability of carbon support and platinum, proton conductivity and electron conductivity in an electrode. In this study, we compare the adsorption...... that the platinization step modifies the surface nature of the carbon supports in terms of specific surface area, crystallinity and especially porosity; therefore, ionomer adsorption over carbon is not always representative for the ionomer adsorption over carbon supported catalyst, though indicative. Moreover...

  14. Exploiting the pyrazolo[3,4-d]pyrimidin-4-one ring system as a useful template to obtain potent adenosine deaminase inhibitors.

    Science.gov (United States)

    La Motta, Concettina; Sartini, Stefania; Mugnaini, Laura; Salerno, Silvia; Simorini, Francesca; Taliani, Sabrina; Marini, Anna Maria; Da Settimo, Federico; Lavecchia, Antonio; Novellino, Ettore; Antonioli, Luca; Fornai, Matteo; Blandizzi, Corrado; Del Tacca, Mario

    2009-03-26

    A number of pyrazolo[3,4-d]pyrimidin-4-ones bearing either alkyl or arylalkyl substituents in position 2 of the nucleus were synthesized and tested for their ability to inhibit adenosine deaminase (ADA) from bovine spleen. The 2-arylalkyl derivatives exhibited excellent inhibitory activity, showing Ki values in the nanomolar/subnanomolar range. The most active compound, 1-(4-((4-oxo-4,5-dihydropyrazolo[3,4-d]pyrimidin-2-yl)methyl)phenyl)-3-(4-(trifluoromethyl)phenyl)urea, 14d, was tested in rats with colitis induced by 2,4-dinitrobenzenesulfonic acid to assess its efficacy to attenuate bowel inflammation. The treatment with 14d induced a significant amelioration of both systemic and intestinal inflammatory alterations in animals with experimental colitis. Docking simulations of the synthesized compounds into the ADA catalytic site were also performed to rationalize the structure-activity relationships observed and to highlight the key pharmacophoric elements of these products, thus prospectively guiding the design of novel ADA inhibitors.

  15. Carbon nanotube/platinum nanoparticle nanocomposites: preparation, characterization and application in electro oxidation of alcohols

    International Nuclear Information System (INIS)

    Kalinke, Adir H.; Zarbin, Aldo J. G.

    2014-01-01

    The synthesis and characterization of different platinum nanoparticle/ carbon nanotube nanocomposite samples are described along with the application of these nanocomposites as electrocatalysts for alcohol oxidation. Samples were prepared by a biphasic system in which platinum nanoparticles (Pt-NPs) are synthesized in situ in contact with a carbon nanotube (CNT) dispersion. Variables including platinum precursor/CNT ratio, previous chemical treatment of carbon nanotubes, and presence or absence of a capping agent were evaluated and correlated with the characteristic of the synthesized materials. Samples were characterized by Raman spectroscopy, X-ray diffraction, thermogravimetric analysis and transmission electron microscopy. Glassy carbon electrodes were modified by the nanocomposite samples and evaluated as electrocatalysts for alcohol oxidation. Current densities of 56.1 and 79.8/104.7 mA cm -2 were determined for the oxidation of methanol and ethanol, respectively. (author)

  16. Niraparib Maintenance Therapy in Platinum-Sensitive, Recurrent Ovarian Cancer

    NARCIS (Netherlands)

    Mirza, M. R.; Monk, B. J.; Herrstedt, J.; Oza, A. M.; Mahner, S.; Redondo, A.; Fabbro, M.; Ledermann, J. A.; Lorusso, D.; Vergote, I.; Ben-Baruch, N. E.; Marth, C.; Madry, R.; Christensen, R. D.; Berek, J. S.; Dorum, A.; Tinker, A. V.; du Bois, A.; Gonzalez-Martin, A.; Follana, P.; Benigno, B.; Rosenberg, P.; Gilbert, L.; Rimel, B. J.; Buscema, J.; Balser, J. P.; Agarwal, S.; Matulonis, U. A.; van der Zee, A.G.J.

    2016-01-01

    BACKGROUND Niraparib is an oral poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP) 1/2 inhibitor that has shown clinical activity in patients with ovarian cancer. We sought to evaluate the efficacy of niraparib versus placebo as maintenance treatment for patients with platinum-sensitive,

  17. Electrochemical behavior of platinum nanoparticles on a carbon xerogel support modified with a [(trifluoromethyl)-benzenesulfonyl]imide electrolyte.

    Science.gov (United States)

    Liu, Bing; Mei, Hua; DesMarteau, Darryl; Creager, Stephen E

    2014-12-11

    A monoprotic [(trifluoromethyl)benzenesulfonyl]imide (SI) superacid electrolyte was used to covalently modify a mesoporous carbon xerogel (CX) support via reaction of the corresponding trifluoromethyl aryl sulfonimide diazonium zwitterion with the carbon surface. Electrolyte attachment was demonstrated by elemental analysis, acid-base titration, and thermogravimetric analysis. The ion-exchange capacity of the fluoroalkyl-aryl-sulfonimide-grafted carbon xerogel (SI-CX) was ∼0.18 mequiv g(-1), as indicated by acid-base titration. Platinum nanoparticles were deposited onto the SI-grafted carbon xerogel samples by the impregnation and reduction method, and these materials were employed to fabricate polyelectrolyte membrane fuel-cell (PEMFC) electrodes by the decal transfer method. The SI-grafted carbon-xerogel-supported platinum (Pt/SI-CX) was characterized by X-ray diffraction and transmission electron microscopy to determine platinum nanoparticle size and distribution, and the findings are compared with CX-supported platinum catalyst without the grafted SI electrolyte (Pt/CX). Platinum nanoparticle sizes are consistently larger on Pt/SI-CX than on Pt/CX. The electrochemically active surface area (ESA) of platinum catalyst on the Pt/SI-CX and Pt/CX samples was measured with ex situ cyclic voltammetry (CV) using both hydrogen adsorption/desorption and carbon monoxide stripping methods and by in situ CV within membrane electrode assemblies (MEAs). The ESA values for Pt/SI-CX are consistently lower than those for Pt/CX. Some possible reasons for the behavior of samples with and without grafted SI layers and implications for the possible use of SI-grafted carbon layers in PEMFC devices are discussed.

  18. Effects of platinum in biological systems - toxicology and pharmaceutical applications; Wirkungen von Platin in biologischen Systemen - Toxikologie und pharmazeutische Anwendung

    Energy Technology Data Exchange (ETDEWEB)

    Nachtigall, D [Fraunhofer-Institut fuer Toxikologie und Aerosolforschung, Hannover (Germany)

    1998-12-31

    The title of this lecture has intentionally been worded rather vaguely with ``biological systems`` to do justice to the fact that there are meanwhile extensive data available on diverse levels of the toxicology and structure-effect relationships of some platinum compounds. These range from epidemiological descriptions over toxicity studies to molecular biological reaction mechanisms. Any discussion on the toxicity of a substance implies that the substance poses a direct or indirect hazard to humans. In the case of platinum and its compounds there are three main categories of exposure: platinum production including workplaces in the platinum processing industries; clinical treatment with antineoplastic platinum-containing agents; and, finally, the environment, where platinum levels are known to be rising since some years. The association between these exposures becomes clear when one considers the platinum pollution caused by automobile catalytic converters, hospital effluents, and by platinum-containing industrial products in the widest sense. [Deutsch] Der Titel des Vortrages ist mit `biologischen Systemen` sehr allgemein gehalten, da ueber die Toxikologie und die Struktur-Wirkungsbeziehungen einiger Platinverbindungen auf den verschiedensten Ebenen umfangreiche Daten vorliegen. Diese reichen von epidemiologischen Beschreibungen ueber Toxizitaetsstudien bis hin zu molekularbiologischen Reaktionsmechanismen. Die Diskussion um die Toxizitaet von Substanzen impliziert immer die direkte oder indirekte Gefaehrdung des Menschen. Im Falle des Platins und seiner Verbindungen existieren drei wesentliche Expositionsbereiche: Die Platingewinnung sowie die Arbeitsplaetze in der Platin verarbeitenden Industrie, die klinische Behandlung mit antineoplastischen Platinwirkstoffen und schliesslich die Umwelt, in der seit einigen Jahren ansteigende Platinkonzentrationen verzeichnet werden. Die Verbindung zwischen diesen Bereichen wird deutlich, wenn man die Platinimmissionen durch

  19. Effects of platinum in biological systems - toxicology and pharmaceutical applications; Wirkungen von Platin in biologischen Systemen - Toxikologie und pharmazeutische Anwendung

    Energy Technology Data Exchange (ETDEWEB)

    Nachtigall, D. [Fraunhofer-Institut fuer Toxikologie und Aerosolforschung, Hannover (Germany)

    1997-12-31

    The title of this lecture has intentionally been worded rather vaguely with ``biological systems`` to do justice to the fact that there are meanwhile extensive data available on diverse levels of the toxicology and structure-effect relationships of some platinum compounds. These range from epidemiological descriptions over toxicity studies to molecular biological reaction mechanisms. Any discussion on the toxicity of a substance implies that the substance poses a direct or indirect hazard to humans. In the case of platinum and its compounds there are three main categories of exposure: platinum production including workplaces in the platinum processing industries; clinical treatment with antineoplastic platinum-containing agents; and, finally, the environment, where platinum levels are known to be rising since some years. The association between these exposures becomes clear when one considers the platinum pollution caused by automobile catalytic converters, hospital effluents, and by platinum-containing industrial products in the widest sense. [Deutsch] Der Titel des Vortrages ist mit `biologischen Systemen` sehr allgemein gehalten, da ueber die Toxikologie und die Struktur-Wirkungsbeziehungen einiger Platinverbindungen auf den verschiedensten Ebenen umfangreiche Daten vorliegen. Diese reichen von epidemiologischen Beschreibungen ueber Toxizitaetsstudien bis hin zu molekularbiologischen Reaktionsmechanismen. Die Diskussion um die Toxizitaet von Substanzen impliziert immer die direkte oder indirekte Gefaehrdung des Menschen. Im Falle des Platins und seiner Verbindungen existieren drei wesentliche Expositionsbereiche: Die Platingewinnung sowie die Arbeitsplaetze in der Platin verarbeitenden Industrie, die klinische Behandlung mit antineoplastischen Platinwirkstoffen und schliesslich die Umwelt, in der seit einigen Jahren ansteigende Platinkonzentrationen verzeichnet werden. Die Verbindung zwischen diesen Bereichen wird deutlich, wenn man die Platinimmissionen durch

  20. Green(ing) infrastructure

    CSIR Research Space (South Africa)

    Van Wyk, Llewellyn V

    2014-03-01

    Full Text Available the generation of electricity from renewable sources such as wind, water and solar. Grey infrastructure – In the context of storm water management, grey infrastructure can be thought of as the hard, engineered systems to capture and convey runoff..., pumps, and treatment plants.  Green infrastructure reduces energy demand by reducing the need to collect and transport storm water to a suitable discharge location. In addition, green infrastructure such as green roofs, street trees and increased...

  1. Fabrication of isolated platinum nanowire gratings and nanoparticles on silica substrate by femtosecond laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Nakajima, Yasutaka [School of Integrated Design Engineering, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama 223- 8522 (Japan); Nedyalkov, Nikolay [Institute of Electronics, Bulgarian Academy of Sciences, Tzarigradsko shouse 72, Sofia 1784 (Bulgaria); Department of Electronics and Electrical Engineering, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama, 223-8522 (Japan); Takami, Akihiro [School of Integrated Design Engineering, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama 223- 8522 (Japan); Terakawa, Mitsuhiro, E-mail: terakawa@elec.keio.ac.jp [School of Integrated Design Engineering, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama 223- 8522 (Japan); Department of Electronics and Electrical Engineering, Keio University, 3-14-1, Hiyoshi, Kohoku-ku, Yokohama, 223-8522 (Japan)

    2017-02-01

    Highlights: • Formation of HSFL with periodicities shorter than 100 nm. • Structural evolution from platinum nanowire gratings to platinum nanoparticles only by increasing the number of pulses. • Melting and fragmentation of the nanowire gratings would play a key role in structural evolution. - Abstract: We demonstrate the fabrication of isolated platinum nanostructures on a silica substrate by using femtosecond laser. Nanowire gratings which have short periodicities of approximately 50 nm were formed by irradiating a platinum thin film deposited on a fused silica substrate with 800-nm wavelength femtosecond laser pulses. The structural evolution from the nanowire gratings to nanoparticles was observed only by increasing the number of pulses. The periodicities or diameters of the structures showed good uniformity. Scanning electron microscopy of the surfaces and theoretical calculation of temperature profile using a two-temperature model revealed that the structural evolution can be attributed to the fragmentation of the formed nanowires. The presented method provides a simple and high-throughput technique for fabricating both metal nanowire gratings and nanoparticles, which have the potential to be used for the fabrication of optical, electrical and biomedical devices.

  2. Column liquid chromatography applied to concentrating, separating, and determining platinum metals

    International Nuclear Information System (INIS)

    Alimarin, I.P.; Basova, E.M.; Bol'shova, T.A.; Ivanov, V.M.

    1986-01-01

    The present survey deals with high-performance liquid chromatography (HPLC) in relation to the chromatographic behavior of the platinum metals, including separation and determination. The data shows that HPLC is the most promising and effective method of separating metals, including platinum ones. The method provides efficient separation of microgram amoounts of mixtures with a resolving power 3-20 times that of thin-layer chromatography. It is shown that the most promising line of advance in HPLC for inorganic systems lies in the separation and determination of metals as chelates by absorption or ion-pair chromatography. Examples of using HPLC for determining noble metals in particular cases indicate that the metrological characteristics are favorable

  3. Nanostructured gold and platinum electrodes on silicon structures for biosensing

    International Nuclear Information System (INIS)

    Ogurtsov, V I; Sheehan, M M

    2005-01-01

    Gold and platinum metal electrodes on Si/SiO 2 having undergone anisotropic potassium hydroxide (KOH) etch treatment are considered. This treatment etches at different rates and directions in the material resulting in creation of numerous pyramid shaped holes in the silicon substrate. This surface is used to make metal electrodes with increased electrode efficiency. The electrodes can serve as the sensors or as the sensor substrates (for surface polymer modification) and because both gold and platinum are inert they have applications for food safety biosensing. Wine, an economically significant food product, was chosen as a matrix, and impedance spectroscopy (EIS) was selected as a method of investigation of electrode behaviour. Based on results of EIS, different complexity equivalent circuits were determined by applying fitting mean square root optimisation of sensor complex impedance measurements

  4. Structural superlubricity of platinum on graphite under ambient conditions: The effects of chemistry and geometry

    Science.gov (United States)

    Özoǧul, Alper; Ipek, Semran; Durgun, Engin; Baykara, Mehmet Z.

    2017-11-01

    An investigation of the frictional behavior of platinum nanoparticles laterally manipulated on graphite has been conducted to answer the question of whether the recent observation of structural superlubricity under ambient conditions [E. Cihan, S. İpek, E. Durgun, and M. Z. Baykara, Nat. Commun. 7, 12055 (2016)] is exclusively limited to the gold-graphite interface. Platinum nanoparticles have been prepared by e-beam evaporation of a thin film of platinum on graphite, followed by post-deposition annealing. Morphological and structural characterization of the nanoparticles has been performed via scanning electron microscopy and transmission electron microscopy, revealing a crystalline structure with no evidence of oxidation under ambient conditions. Lateral manipulation experiments have been performed via atomic force microscopy under ambient conditions, whereby results indicate the occurrence of structural superlubricity at mesoscopic interfaces of 4000-75 000 nm2, with a noticeably higher magnitude of friction forces when compared with gold nanoparticles of similar contact areas situated on graphite. Ab initio simulations of sliding involving platinum and gold slabs on graphite confirm the experimental observations, whereby the higher magnitude of friction forces is attributed to stronger energy barriers encountered by platinum atoms sliding on graphite, when compared with gold. On the other hand, as predicted by theory, the scaling power between friction force and contact size is found to be independent of the chemical identity of the sliding atoms, but to be determined by the geometric qualities of the interface, as characterized by an average "sharpness score" assigned to the nanoparticles.

  5. Noninvasive estimation of bound and mobile platinum compounds in the kidney using a radiopharmacokinetic model

    International Nuclear Information System (INIS)

    Brechner, R.R.; D'Argenio, D.Z.; Dahalan, R.; Wolf, W.

    1986-01-01

    Nephrotoxicity remains a major limitation in the use of cisplatin [cis-diamminedichloroplatinum(II)]. Although several strategies are in use to limit this serious side effect, none is fully satisfactory. Classical pharmacokinetic studies of cisplatin have been based on blood and urine samples. As nephrotoxicity plays a significant role in the design of the therapeutic strategy, the kidneys should be considered as a separate state in any model formulated for ultimate control purposes. Previous studies of organ pharmacokinetics have relied on population measurements. The authors have developed an organ compartmental model from individual animal data obtained noninvasively. The eight-compartment model used to represent the distribution of cisplatin considers free and bound platinum in plasma, platinum in the erythrocytes, mobile and bound platinum in the kidneys, mobile and bound platinum in the tissues, and platinum in the urine. Data were collected from experiments with anesthetized female rats, after intravenous administration of [195mPt]cisplatin. Both arterial and bladder samples, and multiple images obtained with an Anger camera interfaced to a microcomputer were used. The model was estimated from individual data obtained after injection of a bolus of cisplatin (six animals). The model was validated by using it to predict data obtained from forcing the system with a different input function, a 0.5-h intravenous infusion (three animals). The results of this work show that it is possible to noninvasively study drug kinetics in organs that are not readily accessible to direct measurements in an individual, rather than relying on invasive measurements performed on a population.(ABSTRACT TRUNCATED AT 250 WORDS)

  6. Novel 3-(aminomethyl)naphthoquinone mannich base-platinum(IV) complexes: synthesis, characterization, electrochemical and cytotoxic studies

    International Nuclear Information System (INIS)

    Silva, Gustavo B. da; Neves, Amanda P.; Vargas, Maria D.; Alves, Wagner A.; Marinho-Filho, Jose D.B.; Pessoa, Claudia; Moraes, Manoel O.; Costa-Lotufo, Leticia V.

    2013-01-01

    Three novel platinum(IV) complexes cis,cis,trans-[Pt(HL1-3)Cl 2 (OH) 2 ] 1b-3b(HL = 2-hydroxy-3-[(R 1 -amino)(pyridin-2-yl)methyl]-1,4-naphthoquinone, R 1 = n-butyl, HL1; n-heptyl, HL2 and n-decyl, HL3) have been obtained from the oxidation of the respective precursors cis-[Pt(HL1-3)Cl 2 ] 1a-3a. Cyclic voltammetry studies of 1b-3b in MeCN showed the quasi reversible naphthoquinonate (NQO - , i.e., L - ) redox process and irreversible process attributed to the reduction of the Pt 4+ /Pt 2+ pair, at potentials about 400 mV less negative than for the cisplatin precursor cis,cis,trans-[Pt(NH 3 ) 2 Cl 2 (OH) 2 ]. Hydrogen bond interaction between the naphthoquinone 2-hydroxyl group and an axially coordinated hydroxide ligand in 1b-3b has been proposed to favor the Pt 4+ /Pt 2+ reduction. The cytotoxicity studies against four human cancer cell lines have shown that in general the platinum(IV) and platinum(II)derivatives exhibit the same cytotoxic profile and are all more active than cisplatin. The lowest in vitro IC 50 values have been observed for 2b-3b, which bear ligands with the largest R 1 groups (HL2-HL3) being the most lipophilic. Furthermore similar IC 50 values for platinum(II) and platinum(IV) complexes of the same ligands have been associated with rapid in vitro reduction of the latter complexes to afford 1a-3a. (author)

  7. Pretreatment of Platinum/Tin Oxide-Catalyst

    Science.gov (United States)

    Hess, Robert V.; Paulin, Patricia A.; Miller, Irvin M.; Schryer, David R.; Sidney, Barry D.; Wood, George M.; Upchurch, Billy T.; Brown, Kenneth G.

    1987-01-01

    Addition of CO to He pretreatment doubles catalytic activity. In sealed, high-energy, pulsed CO2 laser, CO and O2 form as decomposition products of CO2 in laser discharge zone. Products must be recombined, because oxygen concentration of more than few tenths of percent causes rapid deterioration of power, ending in unstable operation. Promising low-temperature catalyst for combining CO and O2 is platinum on tin oxide. New development increases activity of catalyst so less needed for recombination process.

  8. Pemetrexed With Platinum Combination as a Backbone for Targeted Therapy in Non-Small-Cell Lung Cancer.

    Science.gov (United States)

    Stinchcombe, Thomas E; Borghaei, Hossein; Barker, Scott S; Treat, Joseph Anthony; Obasaju, Coleman

    2016-01-01

    Standard platinum-based chemotherapy combinations for advanced non-small-cell lung cancer (NSCLC) have reached a plateau in terms of the survival benefit they offer for patients. In addition, the emerging clinical trend of tailored treatment based on patient characteristics has led to the development of therapeutic strategies that target specific cancer-related molecular pathways, including epidermal growth factor receptor (EGFR), angiogenesis, and anaplastic lymphoma kinase inhibitors. Current research is focused on combining targeted therapy with platinum-based chemotherapy in an endeavor to achieve an additional benefit in specific patient populations. Currently, pemetrexed is indicated for use in the first-line, maintenance, and second-line settings for the treatment of nonsquamous NSCLC. The combination of pemetrexed and cisplatin is well tolerated and is the approved standard first-line therapy. Thus, the pemetrexed-platinum backbone provides an attractive option for combination with targeted therapies. This review aims to summarize the current knowledge and future prospects of the use of pemetrexed-platinum as a backbone for combination with targeted therapies for NSCLC. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Pyrazolo[3,4-d]pyrimidines as novel inhibitors of O-acetyl-L-serine sulfhydrylase of Entamoeba histolytica: an in silico study.

    Science.gov (United States)

    Yadava, Umesh; Shukla, Bindesh Kumar; Roychoudhury, Mihir; Kumar, Devesh

    2015-04-01

    Amoebiasis, a worldwide explosive epidemic, caused by the gastrointestinal anaerobic protozoan parasite Entamoeba histolytica, infects the large intestine and, in advance stages, liver, kidney, brain and lung. Metronidazole (MNZ)-the first line medicament against amoebiasis-is potentially carcinogenic to humans and shows significant side-effects. Pyrazolo[3,4-d]pyrimidine compounds have been reported to demonstrate antiamoebic activity. In silico molecular docking simulations on nine pyrazolo[3,4-d]pyrimidine molecules without linkers (molecules 1-9) and nine pyrazolo[3,4-d]pyrimidine molecules with a trimethylene linker (molecules 10-18) along with the reference drug metronidazole (MNZ) were conducted using the modules of the programs Glide-SP, Glide-XP and Autodock with O-acetyl-L-serine sulfhydrylase (OASS) enzyme-a promising target for inhibiting the growth of Entamoeba histolytica. Docking simulations using Glide-SP demonstrate good agreement with reported biological activities of molecules 1-9 and indicate that molecules 2 and 4 may act as potential high affinity inhibitors. Trimethylene linker molecules show improved binding affinities among which molecules 15 and 16 supersede. MD simulations on the best docked poses of molecules 2, 4, 15, 16 and MNZ were carried out for 20 ns using DESMOND. It was observed that the docking complexes of molecules 4, 15 and MNZ remain stable in aqueous conditions and do not undergo noticeable fluctuations during the course of the dynamics. Relative binding free energy calculations of the ligands with the enzyme were executed on the best docked poses using the molecular mechanics generalized Born surface area (MM-GBSA) approach, which show good agreement with the reported biological activities.

  10. Design, synthesis and antifungal activities of novel strobilurin derivatives containing pyrimidine moieties

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiang; Geo, Yongxin; Liu, Huijun; Guo, Baoyuan; Wang, Huili [Research Center for Eco-Environmental Sciences/Chinese Academy of Sciences, Beijing (China)

    2012-04-15

    Strobilurins are one of the most important classes of agricultural fungicides. To discover new strobilurin derivatives with high activity against resistant pathogens, a series of novel β-methoxy acrylate analogues were designed and synthesized by integrating substituted pyrimidine with a strobilurin pharmacophore. The compounds were confirmed and characterized by infrared, {sup 1}H nuclear magnetic resonance, elemental analysis and mass spectroscopy. The bioassays indicated that most of the compounds (1a-1h) exhibited potent antifungal activities against Colletotrichum orbicular, Botrytis cinerea Pers and Protoporphyria caps ici Leon ian at the concentration of 50 μg/mL. Exhilaratingly, compound 1d (R=3-trifluoromethylphenyl) showed better antifungal activity against all the tested fungi than the commercial stilbenetriol fungicide azoxystrobin.

  11. Diffuse X-Ray Scattering from Several Platinum Chain Compounds

    DEFF Research Database (Denmark)

    Braude, A.; Lindegaard-Andersen, Asger; Carneiro, K.

    1980-01-01

    Values of the Fermi wavevector for several platinum based one-dimensional conductors were determined from diffuse X-ray scattering measurements. The values were compared with those expected from the chemical compositions. The importance of conclusive values of this parameter is stressed and the c...

  12. Platinum bioaccumulation by mustard plants (Sinapis alba L.)

    International Nuclear Information System (INIS)

    Hawienczyk, M.; Bystrzejewska-Piotrowska, G.; Kowalska, J.; Asztemborska, M.

    2005-01-01

    The ability of hydroponically cultivated Indian mustard plants (Sinapis alba L.) to accumulate platinum was investigated. The Pt-bioaccumulation in leaves, stem and shoots of plants growing for 2 and 4 weeks at Pt-concentration of 50 and 500 μg/L was compared. The relation between dry and fresh weight was also estimated. Adsorptive stripping voltammetry (AdSV) and mass spectrometry with inductively coupled plasma (ICP-MS) were applied for determination of Pt. Increasing Pt-concentration from 50 to 500 μg/L in the medium causes: (1) reduction of the root tissue hydration level at unchanged modification in aboveground parts of the plants and (2) decrease of the Pt transfer factor (TF) for roots and increase for leaves and stem. Duration of the culture influenced on Pt-accumulation in roots and in aboveground organs of mustard plants. Transfer factor for Pt between 560 and 1600 makes Indian mustard plants one at Pt-hyperaccumulators. Distribution of Pt-bioaccumulation in the plant organs may be useful for biomonitoring of platinum in the environment. (author)

  13. Study of half-sandwich mono and dinuclear complexes of platinum ...

    Indian Academy of Sciences (India)

    of platinum group metals containing pyrazolyl pyridine analogues: Synthesis ... sis for specific reactions. Inclusion of ... was poured in to 100 ml of water, resulted in whitish precipitate ..... condition in the presence of potassium carbonate and.

  14. Photocatalytically active colloidal platinum-decorated cadmium sulphide nanorods for hydrogen production; Photokatalytisch Aktive Kolloidale Platindekorierte Cadmiumsulfidnanostaebchen zur Wasserstoffproduktion

    Energy Technology Data Exchange (ETDEWEB)

    Berr, Maximilian Josef

    2012-12-07

    This is the first study to have been successful in producing hydrogen by means of photocatalytically active colloidal semiconductor particles. Specifically, colloidal platinum-decorated cadmium sulphide nanorods were used to reduce water to hydrogen. Oxidation of water to oxygen was substituted by addition of a reducing agent (hole collector), e.g. sulphite, which itself is oxidised to sulphate by the photohole. During photochemical platinum decoration it was discovered that in addition to the expected platinum nanoparticles there had also formed platinum clusters in the subnanometer range. In spite of the small quantity of platinum deposited on the nanorods these clusters showed the same quantum efficiency as the intended product. [German] In dieser Arbeit wurde erstmals mit kolloidalen Halbleiternanopartikeln photokatalytische Wasserstoffproduktion erzielt. Im Detail wurde Wasser mit kolloidalen, platindekorierten Cadmiumsulfidnanostaebchen zu Wasserstoff reduziert. Die Oxidation des Wasser zu Sauerstoff wurde durch Zugabe eines Reduktionsmittels (Lochfaenger) substituiert, z.B. Sulfit, das durch das Photoloch zu Sulfat reduziert wird. Bei der photochemischen Platindekoration wurden neben den erwarteten Platinnanopartikeln mit 4 - 5 nm Durchmesser auch Subnanometer grosse Platincluster entdeckt, die trotz der geringeren Menge an deponierten Platin auf den Nanostaebchen die gleiche Quanteneffizienz demonstrieren.

  15. Liquid-liquid extraction/separation of platinum(IV) and rhodium(III) from acidic chloride solutions using tri-iso-octylamine

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jin-Young, E-mail: jinlee@kigam.re.kr [Metals Recovery Department, Minerals Resources Research Division, Korea Institute of Geoscience and Mineral Resources (KIGAM), 92 Gahangno, Yuesong-gu, Daejeon 305-350 (Korea, Republic of); Rajesh Kumar, J., E-mail: rajeshkumarphd@rediffmail.com [Metals Recovery Department, Minerals Resources Research Division, Korea Institute of Geoscience and Mineral Resources (KIGAM), 92 Gahangno, Yuesong-gu, Daejeon 305-350 (Korea, Republic of); Kim, Joon-Soo; Park, Hyung-Kyu; Yoon, Ho-Sung [Metals Recovery Department, Minerals Resources Research Division, Korea Institute of Geoscience and Mineral Resources (KIGAM), 92 Gahangno, Yuesong-gu, Daejeon 305-350 (Korea, Republic of)

    2009-08-30

    Liquid-liquid extraction/separation of platinum(IV) and rhodium(III) from acidic chloride solutions was carried out using tri-iso-octylamine (Alamine 308) as an extractant diluted in kerosene. The percentage extraction of platinum(IV) and rhodium(III) increased with increase in acid concentration up to 8 mol L{sup -1}. However, at 10 mol L{sup -1} HCl concentration, the extraction behavior was reversed, indicating the solvation type mechanism during extraction. The quantitative extraction of {approx}98% platinum(IV) and 36% rhodium(III) was achieved with 0.01 mol L{sup -1} Alamine 308. The highest separation factor (S.F. = 184.7) of platinum(IV) and rhodium(III) was achieved with 0.01 mol L{sup -1} Alamine 308 at 1.0 mol L{sup -1} of hydrochloric acid concentration. Alkaline metal salts like sodium chloride, sodium nitrate, sodium thiocyanate, lithium chloride, lithium nitrate, potassium chloride and potassium thiocyanate used for the salting-out effect. LiCl proved as best salt for the extraction of platinum(IV). Temperature effect demonstrates that the extraction process is exothermic. Hydrochloric acid and thiourea mixture proved to be better stripping reagents when compared with other mineral acids and bases.

  16. Sub-10 nm structures on silicon by thermal dewetting of platinum

    International Nuclear Information System (INIS)

    Strobel, Sebastian; Kirkendall, Christopher; Chang, Jae-Byum; Berggren, Karl K

    2010-01-01

    A study of the dewetting behavior of platinum-thin-films on silicon was carried out to determine how variation of dewetting parameters affects the evolution of film morphology and to pinpoint which parameters yielded the smallest, most circular features. Platinum film thickness as well as dewetting time and temperature were varied and the film morphology characterized by means of scanning electron microscopy (SEM) analysis. Two different pathways of dewetting predicted in the literature (Vrij 1966 Discuss. Faraday Soc. 42 23, Becker et al 2003 Nat. Mater. 2 59-63) were observed. Depending on the initial criteria, restructuring of the film occurred via hole or droplet formation. With increased annealing time, a transition from an intermediate network structure to separated islands occurred. In addition, the formation of multilayered films, silicide crystals and nanowires occurred for certain parameters. Nevertheless, the dewetting behavior witnessed could be related to physical processes. Droplets with a mean diameter of 9 nm were formed by using a 1.5 nm thick platinum film annealed at 800 deg. C for 30 s. To demonstrate the suitability of the annealed films for further processing, we then used the dewetted films as masks for reactive ion etching to transfer the pattern into the silicon substrate, forming tapered nanopillars.

  17. Accumulation of platinum group elements by the marine gastropod Littorina littorea

    Energy Technology Data Exchange (ETDEWEB)

    Mulholland, Rachel [School of Geography, Earth and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom); Turner, Andrew, E-mail: aturner@plymouth.ac.uk [School of Geography, Earth and Environmental Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA (United Kingdom)

    2011-04-15

    The accumulation and trophic transfer of the platinum group elements (PGE): Rh, Pd and Pt; have been studied in short-term (5 day) exposures conducted in aquaria containing the marine macroalga, Ulva lactuca, and/or the grazing mollusc, Littorina littorea. Metals added to sea water (to concentrations of 20 {mu}g L{sup -1}) were taken up by U. lactuca in the order Rh, Pt > Pd and by L. littorea in the order Pd {>=} Pt {>=} Rh, with greatest metal accumulation in the latter generally occurring in the visceral complex and kidney. When fed contaminated alga, accumulation of Rh and Pd by L. littorea, relative to total available metal, increased by an order of magnitude, while accumulation of Pt was not readily detected. We conclude that the diet is the most important vector for accumulation of Rh and Pd, while accumulation of Pt appears to proceed mainly from the aqueous phase. - Research highlights: > Platinum group elements are accumulated by, Littorina littorea. > The aqueous phase and diet are important vehicles for Rh and Pd accumulation by the snail. > Grazing molluscs may serve as biomonitors of coastal PGE contamination. - Platinum group elements are accumulated by the marine snail, Littorina littorea, from both the aqueous phase and the diet.

  18. Dissolved Platinum Concentrations in Coastal Seawater: Boso to Sanriku Areas, Japan.

    Science.gov (United States)

    Mashio, Asami Suzuki; Obata, Hajime; Gamo, Toshitaka

    2017-08-01

    Platinum, one of the rarest elements in the earth's crust, is now widely used in a range of products, such as catalytic converters in automobiles and anticancer drugs. Increasing use and dispersal of platinum has the potential to affect aquatic environments. Platinum concentrations in open ocean seawater have been found to be very low (approximately 0.2 pmol/L); however, Pt distributions and biogeochemical cycles in coastal areas are unknown. In this study, we investigated Pt concentrations in coastal waters between the Boso and Sanriku areas, Japan, after the 2011 tsunami. We determined sub-picomolar levels of dissolved Pt using isotope-dilution Inductively coupled plasma mass spectrometry after column preconcentration with an anion exchange resin. Dissolved Pt concentrations were found to be in the range 0.20-1.5 pmol/L, with the highest concentration in bottom water of the Boso coastal area, and at stations close to Tokyo Bay. Assuming thermodynamical equilibrium, Pt was determined to be present in the form PtCl 5 (OH) 2- , even in low-oxygen coastal waters. Vertical profiles indicated Pt levels increased toward seafloors near coastal stations and were similar to those of the open ocean at trench stations. High concentrations of dissolved Pt are thought to be derived from coastal sediments.

  19. Role of bonding mechanisms during transfer hydrogenation reaction on heterogeneous catalysts of platinum nanoparticles supported on zinc oxide nanorods

    Science.gov (United States)

    Al-Alawi, Reem A.; Laxman, Karthik; Dastgir, Sarim; Dutta, Joydeep

    2016-07-01

    For supported heterogeneous catalysis, the interface between a metal nanoparticle and the support plays an important role. In this work the dependency of the catalytic efficiency on the bonding chemistry of platinum nanoparticles supported on zinc oxide (ZnO) nanorods is studied. Platinum nanoparticles were deposited on ZnO nanorods (ZnO NR) using thermal and photochemical processes and the effects on the size, distribution, density and chemical state of the metal nanoparticles upon the catalytic activities are presented. The obtained results indicate that the bonding at Pt-ZnO interface depends on the deposition scheme which can be utilized to modulate the surface chemistry and thus the activity of the supported catalysts. Additionally, uniform distribution of metal on the catalyst support was observed to be more important than the loading density. It is also found that oxidized platinum Pt(IV) (platinum hydroxide) provided a more suitable surface for enhancing the transfer hydrogenation reaction of cyclohexanone with isopropanol compared to zero valent platinum. Photochemically synthesized ZnO supported nanocatalysts were efficient and potentially viable for upscaling to industrial applications.

  20. Nanolithographic Fabrication and Heterogeneous Reaction Studies ofTwo-Dimensional Platinum Model Catalyst Systems

    Energy Technology Data Exchange (ETDEWEB)

    Contreras, Anthony Marshall [Univ. of California, Berkeley, CA (United States)

    2006-05-20

    In order to better understand the fundamental components that govern catalytic activity, two-dimensional model platinum nanocatalyst arrays have been designed and fabricated. These catalysts arrays are meant to model the interplay of the metal and support important to industrial heterogeneous catalytic reactions. Photolithography and sub-lithographic techniques such as electron beam lithography, size reduction lithography and nanoimprint lithography have been employed to create these platinum nanoarrays. Both in-situ and ex-situ surface science techniques and catalytic reaction measurements were used to correlate the structural parameters of the system to catalytic activity.

  1. HydroCoil as an adjuvant to bare platinum coil treatment of 100 cerebral aneurysms

    International Nuclear Information System (INIS)

    Fanning, Noel F.; Berentei, Zsolt; Brennan, Paul R.; Thornton, John

    2007-01-01

    Introduction The overall safety of the HydroCoil, an expansile hybrid hydrogel-platinum coil, is unknown. We report a prospective observational study of our first 100 cerebral aneurysms treated with HydroCoils, focusing on safety and initial efficacy.Methods Indications, procedural complications, clinical and angiographic outcomes were recorded. Packing density, number of coils deployed and angiographic results were compared with those in a matched control group of 100 aneurysms treated solely with bare platinum coils. HydroCoil complication rates were compared to bare platinum coil rates at our institution and in published series. Results Adjuvant HydroCoil treatment led to increased mean percentage aneurysm filling compared to controls (50 ± 21% versus 27 ± 13%, P < 0.001). Immediate posttreatment angiographic results showed significantly (P < 0.001) more complete occlusions and fewer incomplete (<95%) occlusions compared to controls. Intermediate follow-up angiograms (median 7.5 months) in 63 aneurysms showed a trend towards fewer incomplete occlusions with HydroCoil treatment. There were significantly fewer major recurrences with HydroCoil treatment compared to the control treatment (9.5% versus 22.6%, P 0.046). In the adjuvant HydroCoil group, major recurrent aneurysms had significantly less percentage volume packing with HydroCoils than non-recurrent aneurysms (50.3 ± 5.0% versus 65.3 ± 18.0%, P = 0.04). There was a 12% procedural complication rate, 6% procedural morbidity and 1% mortality rate, similar to institutional and reported bare platinum coil complication rates.Conclusion HydroCoils can be safely deployed with a similar complication rate to bare platinum coils. They result in improved aneurysm filling. Intermediate follow-up angiography showed significantly fewer major recurrences. Long-term follow-up is required to confirm initial improved stability. (orig.)

  2. Potentiometric sulfite biosensor based on entrapment of sulfite oxidase in a polypyrrole film on a platinum electrode modified with platinum nanoparticles

    International Nuclear Information System (INIS)

    Adeloju, Samuel B.; Hussain, Shahid

    2016-01-01

    The surface of a platinum electrode has been modified with platinum nanoparticles (PtNPs) and the enzyme sulfite oxidase (SOx), was entrapped on its surface in an ultrathin polypyrrole (PPy) film. The PtNPs, with a diameter of 30-40 nm, were deposited on the Pt electrode by cycling the electrode potential 20 times from -200 to 200 mV at a sweep rate of 50 mV.s"-"1. Morphological evidence of the successful incorporation of SOx and the presence of PtNPs were obtained by scanning electron microscopy. Also, the electrochemical behavior of the PtNPs/PPy-SOx film was examined by cyclic voltammetry, chronopotentiometry, electrochemical impedance spectroscopy and potentiometry. Under optimized conditions, the biosensor achieved a sensitivity of 57.5 mV.decade"-"1, a linear response that extends from 0.75 to 65 μM of sulfite, a detection limit of 12.4 nM, and a response time of 3-5 s. The biosensor was successfully applied to the determination of sulfite in wine and beer samples. (author)

  3. Modelling and sensitivity analysis of urinary platinum excretion in anticancer chemotherapy for the recovery of platinum

    DEFF Research Database (Denmark)

    Folens, Karel; Mortier, Séverine Thérèse F C; Baeten, Janis

    2016-01-01

    Platinum (Pt) based antineoplastics are important in cancer therapy. To date the Pt which is urinary excreted by the patients ends up in wastewater. This is disadvantageous from both an economic as from an ecological point of view because Pt is a valuable material and the excretion products...... are toxic for aquatic organisms. Therefore, efforts should be made to recover the Pt. The urinary excretion of Pt from two antineoplastics are taken under consideration, i.e. cisplatin and carboplatin. Using these reference compounds, a scenario analysis based on administration statistics from Ghent...

  4. A Meta-Analysis of Platinum Plus Gemcitabine or Vinorelbine for Advanced Non-small Cell Lung Cancer

    Directory of Open Access Journals (Sweden)

    Guanghui GAO

    2009-01-01

    Full Text Available Background and objective Platinum plus the third-generation agent doublet chemotherapy is the standard regimens and first line chemotherapy for advanced non-small cell lung cancer (NSCLC. The aim of this study is to determine the benefits and harms of platinum plus gemcitabine or vinorelbine for advanced NSCLC. Methods Thedatabases PubMed, CENTRAL, EMBASE and Chinese Biomedical Literature database were retrieved by using the key words "non small cell lung cancer" or "Carcinoma, Non Small Cell Lung" so as to search the studies about the randomized controlled clinical trials (RCT that had compared the gemcitabine plus platinum versus vinorelbine plus platinum for advanced NSCLC. A meta-analysis was conducted. Results Nine randomized controlled trials, with total 2 186 patients,were included. The overall response rate and one-year survival rate of the gemcitabine group were not significantly different from that of vinorelbine regimen (RR=0.91, 95%CI: 0.81-1.03, P =0.15; RR=1.06, 95%CI: 0.96-1.18, P =0.27, respectively. The incidence rate of grade 3-4 netropenia, constipation, phlebitis and grade 1-4 neuropathy were higher in vinorelbine group, just like higher incidence rate of grade 3-4 thrombocytopenia in the gemcitabine group. Conclusion The curative effects of the gemcitabine or vinorelbine plus platinum regimens are similar. The choice of gemcitabine or vinorelbine depends on the toxicity of the drugs and patients' tolerance.

  5. Electrochemical titration of hydrogen adsorbed on supported platinum catalysts

    Czech Academy of Sciences Publication Activity Database

    Paseka, Ivo

    2007-01-01

    Roč. 329, - (2007), s. 161-163 ISSN 0926-860X R&D Projects: GA ČR GA104/03/0409 Institutional research plan: CEZ:AV0Z40320502 Keywords : platinum * hydrogen adsorption * specific surface area Subject RIV: CA - Inorganic Chemistry Impact factor: 3.166, year: 2007

  6. Leading the next boom? competitive Eastern limb platinum supply

    CSIR Research Space (South Africa)

    McGill, JE

    2010-07-01

    Full Text Available in USD/troy oz (Data source: Johnson Matthey) Figure 4. Variation in nominal PGEs spot price from July 1992 till July 2010 in USD/troy oz (Data source: Johnson Matthey) PLATINUM IN TRANSITION ?BOOM OR BUST?4 each. In 1996 and 2003 merger attempts...

  7. Pyrimidine dimers in Drosophila chromatin become increasingly accessible after irradiation

    International Nuclear Information System (INIS)

    Harris, P.V.; Boyd, J.B.

    1987-01-01

    A prokaryotic DNA-repair enzyme has been utilized as a probe for changes in the accessibility of pyrimidine dimers in Drosophila chromatin following UV irradiation. The results demonstrate a rapid cellular response to physiologically relevant doses of radiation which results in at least a 40% increase in accessible dimers. This increase occurs in two incision-deficient mutants which indicates that the excision-repair process, at or beyond the incision step, is not required or responsible for the increase. In the absence of excision the increase in accessibility persists for a least 2 days following irradiation. The observed increase in accessibility is inhibited by both novobiocin and coumermycin. These inhibitors do not inhibit the initial rate of incision, but do reduce dimer excision measured over more extended periods. A pre-incision process is proposed which actively exposes DNA lesions to excision repair. A fraction of the genome is postulated to be accessible without the intervention of that process. (Auth.)

  8. Non-nitro radiation sensitizers

    International Nuclear Information System (INIS)

    Jacobs, G.P.

    1986-01-01

    This short communication aims to update the review of non-nitro radiation sensitizers (Shenoy and Singh 1985) and correct omissions. Work is mentioned and bibliography given for studied of cis-platinum, potassium permanganate, cobalt hexammine, sodium bromide, dimethylsulphoxide, zinc and copper ions, organic nitroxyl free radicals (TAN,TMPN and NPPN + PNAP), halogenated pyrimidines, organic and inorganic iodine containing compounds, diacetyl, acetone and acetophenone, rho-hydrobenzoic acid and its esters, pentobarbitone and secobarbitone, heparin and 9-anilinoacridines, dehydropiandosterone and paraquat. (U.K.)

  9. Removal of pyrimidine dimers from Saccharomyces cerevisiae nuclear DNA under nongrowth conditions as detected by a sensitive, enzymatic assay

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, R J [Tennessee Univ., Oak Ridge (USA). Graduate School of Biomedical Sciences

    1978-04-01

    A sensitive and quantitative procedure for the detection of pyrimidine dimers in yeast nuclear DNA is described. The assay employs dimer-specific, endonuclease activities from Micrococcus luteus together with DNA sedimentation through calibrated, alkaline sucrose gradients to detect endonuclease-induced, single-strand breaks. Breaks were induced in a dose-dependent manner from 0 to 80 J m/sup -2/ at 254 nm and in numbers equivalent to the numbers of dimers induced by similar doses. Endonuclease-sensitive sites in the wild-type, haploid strain S288C, after irradiation with 5 J m/sup -2/ (254 nm), were removed in less than 5 min when cells were incuba ted in buffer (pH 7.0) at 28/sup 0/C. After irra diation with dos es from 30 to 100 J m/sup -2/ site removal in S288C required longer postirradiation incubations and was about 90% complete. In a radiation-sensitive strain carrying the mutant allele rad 4-3 the number of endonuclease-sensitive sites remained constant for 6 h after irradiation with 5 J m/sup -2/. The retention of sites in this strain indicates that it is defective in the excision of pyrimidine dimers. (Auth.

  10. Development of novel (1-H benzimidazole bearing pyrimidine-trione based MAO-A inhibitors: Synthesis, docking studies and antidepressant activity

    Directory of Open Access Journals (Sweden)

    Bijo Mathew

    2016-09-01

    Full Text Available The synthesis of some novel (1-H benzimidazole bearing pyrimidine-trione based MAO-A inhibitors were achieved by the reaction between 2E-1-(1H-benzimidazol-2-yl-3-phenylprop-2-en-1-ones(4a–f and barbituric acid in the presence of a catalytic amount of acetic acid medium. All the final structures were assigned on the basis of IR, 1HNMR and mass spectra analyses. All the synthesized derivatives showed good antidepressant activity when compared to the standard clomipiramine at a dose level of 20 mg/kg. The compound (5d 5-{(2E-1-(1H-benzimidazol-2-yl-3-[4-(dimethylaminophenyl] prop-2-en-1-ylidene} pyrimidine-2, 4, 6(1H,3H,5H-trione significantly reduced the duration of immobility times at 50 mg/kg−1 dose level when compared to the standard drug. Molecular docking studies revealed the need for an extra hydrophobic interaction in the titled scaffold for acquiring the promising experimental values. It has been concluded that the computational values obtained after the docking calculation are in good agreement with the experimental values.

  11. Spectroscopic and theoretical investigation of conformational changes of proteins by synthesized pyrimidine derivative and its sensitivity towards FRET application

    Science.gov (United States)

    Ghosh, Swadesh; Singharoy, Dipti; Bhattacharya, Subhash Chandra

    2018-04-01

    Interest in synthesizing and characterizing (IR, NMR and HRMS spectroscopic methods) a pyrimidine based Schiff-base ligand, 2-(2-(Anthracen-9-ylmethylene) hydrazinyl)-4,6-dimethyl pyrimidine (ANHP) has been developed for its application to ascertain the conformational change of protein and sensitivity towards fluorescence resonance energy transfer (FRET) process. Location of ANHP in bovine serum albumin (BSA) and human serum albumin (HSA) proteins environment has been determined using different spectroscopic techniques. Weakly fluorescent ANHP have shown greater protein induced fluorescence enhancement (PIFE) in case of HSA than BSA, though in both cases energy transfer efficiency are almost same but difference in binding constant values encourages us to find the location of ANHP within the complex protein environment. From the FRET parameter and α-helicity change, it has been found that ANHP bound with Trp-214 of HSA and surface Trp-134 of BSA. Conformational changes of proteins have been observed more for HSA than BSA in presence of ANHP, which has confirmed the location of ANHP in both the protein environments. Coupled with experimental studies, molecular docking analysis has also been done to explain the locations and distance dependent FRET process of ANHP in both proteins.

  12. Determination of platinum and gold in biological materials by neutron activation analysis

    International Nuclear Information System (INIS)

    Taskaev, E.; Grigorov, T.

    1988-01-01

    A procedure for platinum and gold determination utilizing neutron activation combined with radiochemical separation was developed. The reaction 198 Pt (n, γ) 199 Pt undergoing β decay into 199 Au is used for Pt determination. Four procedures for gold separation are examined: adsorption on untreated polyurethane foam (UPF), extraction with dibutyl sulphide, reduction of gold to elementary state in conc. H 2 SO 4 , and extraction of gold as diethyl-dithiocarbamate complex. The extraction with Cu(DDC) 2 is chosen as the most suitable process and applied to platinum and gold determinations in Bowen's Kale and mice organs, previously treated with Biocisplatinum specimens. (author) 12 refs.; 5 figs

  13. Textured strontium titanate layers on platinum by atomic layer deposition

    Energy Technology Data Exchange (ETDEWEB)

    Blomberg, T., E-mail: tom.blomberg@asm.com [ASM Microchemistry Ltd., Vaeinoe Auerin katu 12 A, 00560 Helsinki (Finland); Anttila, J.; Haukka, S.; Tuominen, M. [ASM Microchemistry Ltd., Vaeinoe Auerin katu 12 A, 00560 Helsinki (Finland); Lukosius, M.; Wenger, Ch. [IHP, Im Technologiepark 25, 15236 Frankfurt (Oder) (Germany); Saukkonen, T. [Aalto University, Puumiehenkuja 3, 02150 Espoo (Finland)

    2012-08-31

    Formation of textured strontium titanate (STO) layers with large lateral grain size (0.2-1 {mu}m) and low X-ray reflectivity roughness ({approx} 1.36 nm) on Pt electrodes by industry proven atomic layer deposition (ALD) method is demonstrated. Sr(t-Bu{sub 3}Cp){sub 2}, Ti(OMe){sub 4} and O{sub 3} precursors at 250 Degree-Sign C were used to deposit Sr rich STO on Pt/Ti/SiO{sub 2}/Si Empty-Set 200 mm substrates. After crystallization post deposition annealing at 600 Degree-Sign C in air, most of the STO grains showed a preferential orientation of the {l_brace}001{r_brace} plane parallel to the substrate surface, although other orientations were also present. Cross sectional and plan view transmission electron microscopy and electron diffraction analysis revealed more than an order of magnitude larger lateral grain sizes for the STO compared to the underlying multicrystalline {l_brace}111{r_brace} oriented platinum electrode. The combination of platinum bottom electrodes with ALD STO(O{sub 3}) shows a promising path towards the formation of single oriented STO film. - Highlights: Black-Right-Pointing-Pointer Amorphous strontium titanate (STO) on platinum formed a textured film after annealing. Black-Right-Pointing-Pointer Single crystal domains in 60 nm STO film were 0.2-1 {mu}m wide. Black-Right-Pointing-Pointer Most STO grains were {l_brace}001{r_brace} oriented.

  14. Our Expedition in Linear Neutral Platinum-Acetylide Complexes: The Preparation of Micro/nanostructure Materials, Complicated Topologies, and Dye-Sensitized Solar Cells.

    Science.gov (United States)

    Xu, Lin; Yang, Hai-Bo

    2016-06-01

    During the past few decades, the construction of various kinds of platinum-acetylide complexes has attracted considerable attention, because of their wide applications in photovoltaic cells, non-linear optics, and bio-imaging materials. Among these platinum-acetylide complexes, the linear neutral platinum-acetylide complexes, due to their attractive properties, such as well-defined linear geometry, synthetic accessibility, and intriguing photoproperties, have emerged as a rising star in this field. In this personal account, we will discuss how we entered the field of linear neutral platinum-acetylide chemistry and what we found in this field. The preparation of various types of linear neutral platinum-acetylide complexes and their applications in the areas of micro/nanostructure materials, complicated topologies, and dye-sensitized solar cells will be summarized in this account. © 2016 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. MD study of pyrimidine base damage on DNA and its recognition by repair enzyme

    International Nuclear Information System (INIS)

    Pinak, M.

    2000-01-01

    The molecular dynamics (MD) simulation was used on the study of two specific damages of pyrimidine bases of DNA. Pyrimidine bases are major targets either of free radicals induced by ionizing radiation in DNA surrounding environment or UV radiation. Thymine dimer (TD) is UV induced damage, in which two neighboring thymines in one strand are joined by covalent bonds of C(5)-C(5) and C(6)-C(6) atoms of thymines. Thymine glycol (TG) is ionizing radiation induced damage in which the free water radical adds to unsaturated bond C(5)-C(6) of thymine. Both damages are experimentally suggested to be mutagenetic and carcinogenic unless properly repaired by repair enzymes. In the case of MD of TD, there is detected strong kink around the TD site that is not observed in native DNA. In addition there is observed the different value of electrostatic energy at the TD site - negative '-10 kcal/mol', in contrary to nearly neutral value of native thymine site. Structural changes and specific electrostatic energy - seems to be important for proper recognition of TD damaged site, formation of DNA-enzyme complex and thus for subsequent repair of DNA. In the case of TG damaged DNA there is major structural distortion at the TG site, mainly the increased distance between TG and the C5' of adjacent nucleotide. This enlarged gap between the neighboring nucleotides may prevent the insertion of complementary base during replication causing the replication process to stop. In which extend this structural feature together with energy properties of TG contributes to the proper recognition of TG by repair enzyme Endonuclease III is subject of further computational MD study. (author)

  16. Customers’ Intention to Use Green Products: the Impact of Green Brand Dimensions and Green Perceived Value

    Directory of Open Access Journals (Sweden)

    Doszhanov Aibek

    2015-01-01

    Full Text Available This study aimed to identify the relationships between green brand dimension (green brand awareness, green brand image, and green brand trust, green perceived value and customer’s intention to use green products. Data was collected through structured survey questionnaire from 384 customers of three hypermarkets in Kuala-Lumpur. Data was analyzed based on multiple regression analysis. The results indicate that there are significant relationships between green brand awareness, green brand trust, green perceived value, and customer’s intention to use green products. However, green brand image was not found to have significant relationship with customer’s intention to use green products. The discussion presented suggestions for marketers and researchers interested in green branding.

  17. Novel 3-(aminomethyl)naphthoquinone mannich base-platinum(IV) complexes: synthesis, characterization, electrochemical and cytotoxic studies

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Gustavo B. da; Neves, Amanda P.; Vargas, Maria D., E-mail: mdvargas@vm.uff.br [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Instituto de Quimica; Alves, Wagner A. [Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropedica, RJ (Brazil). Departamento de Quimica; Marinho-Filho, Jose D.B.; Pessoa, Claudia; Moraes, Manoel O.; Costa-Lotufo, Leticia V. [Universidade Federal do Ceara (UFCE), Fortaleza, CE (Brazil). Centro de Ciencias da Saude. Departamento de Fisiologia e Farmacologia

    2013-04-15

    Three novel platinum(IV) complexes cis,cis,trans-[Pt(HL1-3)Cl{sub 2}(OH){sub 2}] 1b-3b(HL = 2-hydroxy-3-[(R{sup 1} -amino)(pyridin-2-yl)methyl]-1,4-naphthoquinone, R{sup 1} = n-butyl, HL1; n-heptyl, HL2 and n-decyl, HL3) have been obtained from the oxidation of the respective precursors cis-[Pt(HL1-3)Cl{sub 2}] 1a-3a. Cyclic voltammetry studies of 1b-3b in MeCN showed the quasi reversible naphthoquinonate (NQO{sup -}, i.e., L{sup -}) redox process and irreversible process attributed to the reduction of the Pt{sup 4+}/Pt{sup 2+} pair, at potentials about 400 mV less negative than for the cisplatin precursor cis,cis,trans-[Pt(NH{sub 3}){sub 2}Cl{sub 2}(OH){sub 2}]. Hydrogen bond interaction between the naphthoquinone 2-hydroxyl group and an axially coordinated hydroxide ligand in 1b-3b has been proposed to favor the Pt{sup 4+}/Pt{sup 2+} reduction. The cytotoxicity studies against four human cancer cell lines have shown that in general the platinum(IV) and platinum(II)derivatives exhibit the same cytotoxic profile and are all more active than cisplatin. The lowest in vitro IC{sub 50} values have been observed for 2b-3b, which bear ligands with the largest R{sup 1} groups (HL2-HL3) being the most lipophilic. Furthermore similar IC{sub 50} values for platinum(II) and platinum(IV) complexes of the same ligands have been associated with rapid in vitro reduction of the latter complexes to afford 1a-3a. (author)

  18. The Influence of Proactive Green Innovation and Reactive Green Innovation on Green Product Development Performance: The Mediation Role of Green Creativity

    OpenAIRE

    Yu-Shan Chen; Tai-Wei Chang; Chun-Yu Lin; Pi-Yu Lai; Kuan-Hung Wang

    2016-01-01

    This study fills the research gap in the exploration of the relationships between both proactive and reactive green innovations and green product development performance, and examines the mediating effect of green creativity. Structural equation modeling (SEM) is utilized to test the hypotheses. From the sample of 146 valid respondents, the results show that proactive green innovation positively affects green creativity and green product development performance, and green creativity positivel...

  19. TD-DFT investigation of the magnetic circular dichroism spectra of some purine and pyrimidine bases of nucleic acids.

    Science.gov (United States)

    Fahleson, Tobias; Kauczor, Joanna; Norman, Patrick; Santoro, Fabrizio; Improta, Roberto; Coriani, Sonia

    2015-05-28

    We present a computational study of the magnetic circular dichroism (MCD) spectra in the 200-300 nm wavelength region of purine and its derivative hypoxanthine, as well as of the pyrimidine bases of nucleic acids uracil, thymine, and cytosine, using the B3LYP and CAM-B3LYP functionals. Solvent effects are investigated within the polarizable continuum model and by inclusion of explicit water molecules. In general, the computed spectra are found to be in good agreement with the experimental ones, apart from some overall blue shifts. Both the pseudo-A term shape of the MCD spectra of the purines and the B term shape of the spectra of pyrimidine bases are reproduced. Our calculations also correctly reproduce the reversed phase of the MCD bands in purine compared to that of its derivatives present in nucleic acids. Solvent effects are sizable and system specific, but they do not in general alter the qualitative shape of the spectra. The bands are dominated by the bright π → π* transitions, and our calculations in solution nicely reproduce their energy differences, improving the estimates obtained in the gas phase. Shoulders are predicted for purine and uracil due to n → π* excitations, but they are too weak to be observed in the experiment.

  20. MULTICOMPONENT AND REGIOSELECTIVE SYNTHESIS OF DIHYDROPYRAZOLO[1,5-a]PYRIMIDINES FROM AROMATIC ALDEHYDES, MELDRUM'S ACID AND AMINOPYRAZOLE CAN508

    OpenAIRE

    Jedinák, L.; Kryštof, V. (Vladimír); Trávníček, Z.; Cankař, P.

    2014-01-01

    A regioselective synthesis of dihydropyrazolo[1,5-a]pyrimidines is reported. The multicomponent reaction of readily available arylaldehydes, Meldrum's acid, and aminopyrazole CAN508 afforded fused pyrazolopyrimidines in high yields. The reaction proceeded regioselectively via initial Michael addition of the exocyclic amino group to arylidene Meldrum's acid intermediate followed by a ring closure at the endocyclic nitrogen of aminopyrazole. The regioselectivity of the reaction was determined b...

  1. Retained sensitivity to cytotoxic pyrimidine nucleoside analogs in thymidine kinase 2 deficient human fibroblasts.

    Science.gov (United States)

    Bjerke, Mia; Solaroli, Nicola; Lesko, Nicole; Balzarini, Jan; Johansson, Magnus; Karlsson, Anna

    2010-01-01

    Thymidine kinase 2 (TK2) is a mitochondrial deoxyribonucleoside kinase that phosphorylates several nucleoside analogs used in anti-viral and anti-cancer therapy. A fibroblast cell line with decreased TK2 activity was investigated in order to obtain insights in the effects of TK2 deficiency on nucleotide metabolism. The role of TK2 for the sensitivity against cytotoxic nucleoside analogs was also investigated. The TK2 deficient cells retained their sensitivity against all pyrimidine nucleoside analogs tested. This study suggests that nucleoside analog phosphorylation mediated by TK2 may be less important, compared to other deoxyribonucleoside kinases, for the cytotoxic effects of these compounds.

  2. Enhanced catalytic activity of nanoscale platinum islands loaded ...

    Indian Academy of Sciences (India)

    2016-08-26

    Aug 26, 2016 ... In the present study, different catalysts (∼ 10 nm thick) including metals, noble metals and metal oxides, were loaded in dotted island form over SnO2 thin film for LPG gas detection. A comparison of various catalysts indicated that the presence of platinum dotted islands over SnO2 thin film deposited by r.f. ...

  3. Characterization and bacterial anti-adherent effect on modified PMMA denture acrylic resin containing platinum nanoparticles

    OpenAIRE

    Nam, Ki-Young

    2014-01-01

    PURPOSE This study characterized the synthesis of a modified PMMA (Polymethyl methacrylate) denture acrylic loading platinum nanoparticles (PtN) and assessed its bacterial inhibitory efficacy to produce novel antimicrobial denture base material. MATERIALS AND METHODS Polymerized PMMA denture acrylic disc (20 mm × 2 mm) specimens containing 0 (control), 10, 50, 100 and 200 mg/L of PtN were fabricated respectively. The obtained platinum-PMMA nanocomposite (PtNC) was characterized by TEM (transm...

  4. Cyclobutane-type pyrimidine photodimer formation and induction of ornithine decarboxylase in human skin fibroblasts after UV irradiation

    International Nuclear Information System (INIS)

    Niggli, H.J.; Roethlisberger, R.

    1988-01-01

    Cyclobutane-type pyrimidine photodimers as well as the induction of ornithine decarboxylase (ODC) may serve as biochemical markers of the mutagenic and carcinogenic effects of ultraviolet light (UV). For this reason, it is important to compare the formation of pyrimidine dimers with the induction of ODC in human skin fibroblasts after irradiation with UVC (200-290 nm) and UVB (290-320 nm). In our studies we determined cytosine-thymine (C-T) as well as thymine-thymine dimer yields (T-T) by high-pressure liquid chromatography in cultures of neonatal normal human foreskin-derived fibroblasts after irradiation with UVC and UVB light. It was found that the yield of dimerization and the ratio of T-T/C-T decreased from the UVC to the UVB region. Time-course studies of ODC-induction in the same cells indicated that the maximal activity after UVB irradiation was retarded compared to UVC exposure. For the UV-induced ODC-levels, however, no significant difference in maximal induction could be measured after UVC and UVB irradiation at fluences where comparable yields of thymine dimerization are produced. Similar ODC-maxima were obtained with strains from children, while cells from adults showed significantly less pronounced ODC induction, indicating that ODC-response decreases with age and may therefore be used as a marker of aging

  5. Basophil Activation Test is a Relevant Biomarker of the Outcome of Rapid Desensitization in Platinum Compounds-Allergy.

    Science.gov (United States)

    Giavina-Bianchi, Pedro; Galvão, Violeta Régnier; Picard, Matthieu; Caiado, Joana; Castells, Mariana C

    Rapid drug desensitization (RDD) has become a cornerstone in the management of immediate drug hypersensitivity reactions (DHRs) to chemotherapeutic agents. Because of the inherent risk of anaphylaxis during RDD, biomarkers to predict patients at risk of developing such severe reactions are needed. The basophil activation test (BAT) has been used in DHRs as a diagnostic tool. We evaluated basophil CD63 and CD203c expression (BAT) as a biomarker to assess the safety and effectiveness of RDD in platinum compounds-allergic patients. Patients allergic to platinum compounds (n = 15) undergoing RDD were assessed through clinical history, skin testing, serum tryptase levels, and BAT. BAT was performed immediately before RDD, assessing CD203c and CD63 expression on basophils. BAT was also performed in 6 patients tolerant to platinum compounds and in 6 healthy volunteers. BAT was positive to CD203c or CD63 in 11 out of 15 patients allergic to platinum compounds (73%), with increased expression of CD203c and CD63 in 11 (73%) and 6 (40%) patients, respectively. Increased CD63 expression tended to be associated with more severe initial reactions. All controls had negative test results. Reactions during RDD were associated with BAT positivity and increased tryptase levels. Only 1 of 4 patients with negative BAT had a mild reaction during RDD. BAT remained positive in multiple sequential RDD. BAT identified patients allergic to platinum compounds with an increased risk of reactions during desensitization and higher CD63 expression was observed in severe reactions. Multiple RDDs to platinum compounds did not induce persistent hyporesponsiveness on basophils. BAT is a potential biomarker for RDD. Copyright © 2016 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

  6. Metaphysical green

    DEFF Research Database (Denmark)

    Earon, Ofri

    2011-01-01

    to adapt to urban environment. It explores the potential of Sensation of Green in the city. The paper questions whether the Sensation of Green could introduce a new spectrum of greens, beside the real green. It develops the term of metaphysical green – does green have to be green or can it be only...

  7. Glutamine-dependent carbamoyl-phosphate synthetase and other enzyme activities related to the pyrimidine pathway in spleen of Squalus acanthias (spiny dogfish).

    Science.gov (United States)

    Anderson, P M

    1989-01-01

    The first two steps of urea synthesis in liver of marine elasmobranchs involve formation of glutamine from ammonia and of carbamoyl phosphate from glutamine, catalysed by glutamine synthetase and carbamoyl-phosphate synthetase, respectively [Anderson & Casey (1984) J. Biol. Chem. 259, 456-462]; both of these enzymes are localized exclusively in the mitochondrial matrix. The objective of this study was to establish the enzymology of carbamoyl phosphate formation and utilization for pyrimidine nucleotide biosynthesis in Squalus acanthias (spiny dogfish), a representative elasmobranch. Aspartate carbamoyltransferase could not be detected in liver of dogfish. Spleen extracts, however, had glutamine-dependent carbamoyl-phosphate synthetase, aspartate carbamoyltransferase, dihydro-orotase, and glutamine synthetase activities, all localized in the cytosol; dihydro-orotate dehydrogenase, orotate phosphoribosyltransferase, and orotidine-5'-decarboxylase activities were also present. Except for glutamine synthetase, the levels of all activities were very low. The carbamoyl-phosphate synthetase activity is inhibited by UTP and is activated by 5-phosphoribosyl 1-pyrophosphate. The first three enzyme activities of the pyrimidine pathway were eluted in distinctly different positions during gel filtration chromatography under a number of different conditions; although complete proteolysis of inter-domain regions of a multifunctional complex during extraction cannot be excluded, the evidence suggests that in dogfish, in contrast to mammalian species, these three enzymes of the pyrimidine pathway exist as individual polypeptide chains. These results: (1) establish that dogfish express two different glutamine-dependent carbamoyl-phosphate synthetase activities, (2) confirm the report [Smith, Ritter & Campbell (1987) J. Biol. Chem. 262, 198-202] that dogfish express two different glutamine synthetases, and (3) provide indirect evidence that glutamine may not be available in liver for

  8. Efficacy of tegafur-uracil in advanced urothelial cancer patients after the treatment failure of platinum-based chemotherapy.

    Science.gov (United States)

    Maolake, Aerken; Izumi, Kouji; Takahashi, Rie; Itai, Shingo; Machioka, Kazuaki; Yaegashi, Hiroshi; Nohara, Takahiro; Kitagawa, Yasuhide; Kadono, Yoshifumi; Konaka, Hiroyuki; Mizokami, Atsushi; Namiki, Mikio

    2015-03-01

    Platinum-based chemotherapy is the first-line treatment for advanced urinary tract urothelial cancers. However, the optimal second-line treatment is unclear. Although tegafur-uracil is sometimes used for advanced urothelial cancer patients after the treatment failure of platinum-based chemotherapy, there is little evidence regarding its use as a second-line treatment. Advanced urothelial cancer patients previously treated with platinum-based chemotherapy were retrospectively analyzed. Overall survival (OS) was compared between patients with and without tegafur-uracil treatment. Thirty-one patients (27 and 4 patients with and without tegafur-uracil treatment, respectively) were analyzed. OS from the last day of the final chemotherapy course was better in patients with tegafur-uracil treatment than in those without (p<0.001, 358 and 66.5 days of the median survival time, respectively). Tegafur-uracil may be a candidate for the secondary treatment of advanced urothelial cancer patients after the treatment failure of platinum-based chemotherapy. Copyright© 2015 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.

  9. Platinum incorporation in the Na Y zeolite through impregnation method, and characterization by XRD, FTIR and nitrogen adsorption

    International Nuclear Information System (INIS)

    Araujo, A.S.; Sousa, B.V.; Andrade, A.C.C.; Rodrigues, M.G.F.; Rangel, M.C.

    2007-01-01

    Supported metal catalysts are widely used in petroleum refining, chemical and petroleum industries. These catalysts are important in ammonia synthesis, conversion of hydrocarbons with water vapor to synthesis gas, reforming, hydrocracking, ... Platinum has long been used in cracking, hydrogenation and dehydrogenation processes. The aim of this project is the Na Y zeolitic sample preparation through impregnation for incipient humidity, with 0,5% concentration of platinum, aiming its use as a catalyst in the steam reforming reaction. The characterization techniques used were: X Rays Diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR) and Nitrogen Adsorption (BET Method). From the obtained results through the techniques mentioned previously it is possible to evidence that the platinum impregnation process did not change the Na Y zeolite structure. Through the superficial specific area (BET) it was possible to observe that the platinum impregnation process caused a decrease in the specific area due to the reduction to the accessibility to the micropores of the zeolitic structure. (author)

  10. Novel N-(pyrimidin-4-ylthiazol-2-amine derivatives as dual-action hypoglycemic agents that activate GK and PPARγ

    Directory of Open Access Journals (Sweden)

    Hui-peng Song

    2011-10-01

    Full Text Available A series of novel N-(pyrimidin-4-ylthiazol-2-amine derivatives have been synthesized and evaluated as glucokinase (GK activators. Ethyl 2-(6-(4-(2-hydroxyethylpiperazin-1-yl-2-methylpyrimidin-4-yl-aminothiazole-5-carboxylate was found to be a potent dual-acting hypoglycemic agent activating both GK and PPARγ. When given orally to normal mice, the compound demonstrated significant efficacy in decreasing the glucose level after oral glucose loading.

  11. Evaluation and structure-activity relationship analysis of a new series of 4-imino-5H-pyrazolo[3,4-d]pyrimidin-5-amines as potential antibacterial agents

    Science.gov (United States)

    Beyzaei, Hamid; Aryan, Reza; Moghaddam-Manesh, Mohammadreza; Ghasemi, Behzad; Karimi, Pouya; Samareh Delarami, Hojat; Sanchooli, Mahmood

    2017-09-01

    The synthesis of pyrazolo[3,4-d]pyrimidine derivatives is important due to their presence in various biologically active compounds such as anticancer, antimicrobial, antiparasitic, anti-inflammatory and antidiabetic agents. In this project, a new and efficient approach for the synthesis of some novel 4-imino-5H-pyrazolo[3,4-d]pyrimidin-5-amines from reaction of 5-amino-pyrazole-4-carbonitrile with various hydrazides in ethanolic sodium ethoxide medium was reported. Antimicrobial activities of all synthesized derivatives were evaluated against eight Gram-positive and five Gram-negative pathogenic bacteria. The moderate to good inhibitory effects were observed based on inhibition zone diameter (IZD), minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values. In order to determine the reasonable relationship between antibacterial activities and physiochemical properties of the derivatives, computational studies were carried out in terms of geometry optimization, short-range van der Waals forces, dipole moments, atomic charges and frontier orbital energies. It was found that both short-range forces and covalent bonds are important in the observed inhibitory effects of the molecules. The results suggested that pyrazolo[3,4-d]pyrimidine derivatives prefer a soft nucleophilic attack on bio-macromolecular targets. Furthermore, our models proposed that the antibacterial activities of these derivatives can be improved by substituting large electron donating groups on the 6-phenyl rings.

  12. Prodrugs of Pyrazolo[3,4-d]pyrimidines: From Library Synthesis to Evaluation as Potential Anticancer Agents in an Orthotopic Glioblastoma Model.

    Science.gov (United States)

    Vignaroli, Giulia; Iovenitti, Giulia; Zamperini, Claudio; Coniglio, Federica; Calandro, Pierpaolo; Molinari, Alessio; Fallacara, Anna Lucia; Sartucci, Andrea; Calgani, Alessia; Colecchia, David; Mancini, Andrea; Festuccia, Claudio; Dreassi, Elena; Valoti, Massimo; Musumeci, Francesca; Chiariello, Mario; Angelucci, Adriano; Botta, Maurizio; Schenone, Silvia

    2017-07-27

    Pyrazolo[3,4-d]pyrimidines are potent protein kinase inhibitors with promising antitumor activity but suboptimal aqueous solubility, consequently worth being further optimized. Herein, we present the one-pot two-step procedure for the synthesis of a set of pyrazolo[3,4-d]pyrimidine prodrugs (1a-8a and 9a-e) with higher aqueous solubility and enhanced pharmacokinetic and therapeutic properties. ADME studies demonstrated for the most promising prodrugs a better aqueous solubility, a favorable hydrolysis in human and murine serum, and an increased ability to cross cell membranes with respect to the parental drugs, explaining their better 24 h in vitro cytotoxicity against human glioblastoma U87 cell line. Finally, the 4-4a couple of drug/prodrug was also evaluated in vivo, revealing a profitable pharmacokinetic profile of the prodrug associated with a good efficacy. The application of the prodrug approach demonstrated to be a successful strategy for improving aqueous solubility of the parental drugs, determining a positive impact also in their biological efficacy.

  13. Association of well-characterized lung cancer lncRNA polymorphisms with lung cancer susceptibility and platinum-based chemotherapy response.

    Science.gov (United States)

    Gong, Wei-Jing; Yin, Ji-Ye; Li, Xiang-Ping; Fang, Chao; Xiao, Di; Zhang, Wei; Zhou, Hong-Hao; Li, Xi; Liu, Zhao-Qian

    2016-06-01

    Long non-coding RNAs (lncRNAs) play important roles in carcinogenesis and drug efficacy. Platinum-based chemotherapy is first-line treatment for lung cancer chemotherapy. In this study, we aimed to investigate the association of well-characterized lung cancer lncRNA genetic polymorphisms with the lung cancer susceptibility and platinum-based chemotherapy response. A total of 498 lung cancer patients and 213 healthy controls were recruited in the study. Among them, 467 patients received at least two cycles of platinum-based chemotherapy. Thirteen polymorphisms in HOXA distal transcript antisense RNA (HOTTIP), HOX transcript antisense intergenic RNA (HOTAIR), H19, CDKN2B antisense RNA 1 (ANRIL), colon cancer-associated transcript 2 (CCAT2), metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), and maternally expressed gene 3 (MEG3) genes were genotyped by allele-specific MALDI-TOF mass spectrometry. We found that patients with HOTTIP rs5883064 C allele or rs1859168 A allele had increased lung cancer risk (P = 0.01, P = 0.01, respectively). CCAT2 rs6983267 (P = 0.02, adenocarcinoma) and H19 rs2107425 (P = 0.02, age under 50 years) showed strong relationship with lung cancer susceptibility. CCAT2 rs6983267, H19 rs2839698, MALAT1 rs619586, and HOTAIR rs7958904 were associated with platinum-based chemotherapy response in dominant model ((P = 0.02, P = 0.04, P = 0.04, P = 0.01, respectively). ANRIL rs10120688 (P = 0.02, adenocarcinoma) and rs1333049 (P = 0.04, small-cell lung cancer), H19 rs2107425 (P = 0.02, small-cell lung cancer) and HOTAIR rs1899663 (P = 0.03, male; P = 0.03, smoker) were associated with response to platinum-based chemotherapy. HOTTIP, CCAT2, H19, HOTAIR, MALATI, ANRIL genetic polymorphisms were significantly associated with lung cancer susceptibility or platinum-based chemotherapy response. They may be potential clinical biomarkers to predict lung cancer risk and platinum

  14. Fenarimol, a Pyrimidine-Type Fungicide, Inhibits Brassinosteroid Biosynthesis

    Directory of Open Access Journals (Sweden)

    Keimei Oh

    2015-07-01

    Full Text Available The plant steroid hormone brassinosteroids (BRs are important signal mediators that regulate broad aspects of plant growth and development. With the discovery of brassinoazole (Brz, the first specific inhibitor of BR biosynthesis, several triazole-type BR biosynthesis inhibitors have been developed. In this article, we report that fenarimol (FM, a pyrimidine-type fungicide, exhibits potent inhibitory activity against BR biosynthesis. FM induces dwarfism and the open cotyledon phenotype of Arabidopsis seedlings in the dark. The IC50 value for FM to inhibit stem elongation of Arabidopsis seedlings grown in the dark was approximately 1.8 ± 0.2 μM. FM-induced dwarfism of Arabidopsis seedlings could be restored by brassinolide (BL but not by gibberellin (GA. Assessment of the target site of FM in BR biosynthesis by feeding BR biosynthesis intermediates indicated that FM interferes with the side chain hydroxylation of BR biosynthesis from campestanol to teasterone. Determination of the binding affinity of FM to purified recombinant CYP90D1 indicated that FM induced a typical type II binding spectrum with a Kd value of approximately 0.79 μM. Quantitative real-time PCR analysis of the expression level of the BR responsive gene in Arabidopsis seedlings indicated that FM induces the BR deficiency in Arabidopsis.

  15. Elaboration, physical and electrochemical characterizations of CO tolerant PEMFC anode materials. Study of platinum-molybdenum and platinum-tungsten alloys and composites; Elaborations et caracterisations electrochimiques et physiques de materiaux d'anode de PEMFC peu sensibles a l'empoisonnement par CO: etude d'alliages et de composites a base de platine-molybdene et de platine-tungstene

    Energy Technology Data Exchange (ETDEWEB)

    Peyrelade, E.

    2005-06-15

    PEMFC development is hindered by the CO poisoning ability of the anode platinum catalyst. It has been previously shown that the oxidation potential of carbon monoxide adsorbed on the platinum atoms can be lowered using specific Pt based catalysts, either metallic alloys or composites. The objective is then to realize a catalyst for which the CO oxidation is compatible with the working potential of a PEMFC anode. In our approach, to enhance the CO tolerance of platinum based catalyst supported on carbon, we studied platinum-tungsten and platinum-molybdenum alloys and platinum-metal oxide materials (Pt-WO{sub x} and Pt-MoO{sub x}). The platinum based alloys demonstrate a small effect of the second metal towards the oxidation of carbon monoxide. The platinum composites show a better tolerance to carbon monoxide. Electrochemical studies on both Pt-MoO{sub x} and Pt-WO{sub x} demonstrate the ability of the metal-oxides to promote the ability of Pt to oxidize CO at low potentials. However, chrono-amperometric tests reveal a bigger influence of the tungsten oxide. Complex chemistry reactions on the molybdenum oxide surface make it more difficult to observe. (author)

  16. The effect of complexation with platinum in polyfluorene derivatives: A photo- and electro-luminescence study

    International Nuclear Information System (INIS)

    Assaka, Andressa M.; Hu Bin; Mays, Jimmy; Iamazaki, Eduardo T.; Atvars, Teresa D.Z.; Akcelrud, Leni

    2011-01-01

    The synthesis and characterization of a polymeric structure containing fluorene units statistically linked to 3-cyclohexyl-thiophene and bipyridine PFOTBipy-poly[(4-hexylthiophene-2,5-diyl)(9,9-dihexyl-fluoren-2,7-diyl) -co-(bipyridine-5.5'-diyl)(9,9-dihexyl-fluoren-2,7-diyl)], is reported. The complexation with platinum was possible through the bipyridil units present in 10%, 50% and 100% content. The structure has a fluorenyl moiety between each bipyridine and thiophene groups resulting in a stable and efficient light-emitting polymeric material combining the well known emissive properties of fluorene, the charge mobility generated by thiophene and the electron-transfer properties of a metal complex as well. All the polymers were photo and electroluminescent materials, and showed phosphorescence at low temperatures. Photoluminescence properties were studied by steady state and time resolved spectroscopy and showed changes of both emission peak and relative intensity of the emission bands depending on the relative amount of the platinum complex. The electroluminescence followed the trends found for photoluminescence. The blue emission of the copolymer without platinum is due to the fluorenyl segments and for higher complex contents the emission is characteristic of the aggregates involving the bipyridinyl moieties. Therefore, emission color can be tuned by the complex content. The turn-on voltage was strongly reduced from 22 to 8 V for the 100% complexed copolymer, as compared to the device made with the non complexed one, but the luminance decreased, due to quenching or trapping effects. - Research Highlights: →Statistic copolymer containing fluorine, thiophene and bipyridine. →Complexation of platinum with platinum with bipyridine. →Electroluminescence and electrophosphorescence at low temperatures. →Emission color can be tuned by the complex content.

  17. Decreased UV light resistance of spores of Bacillus subtilis strains deficient in pyrimidine dimer repair and small, acid-soluble spore proteins

    International Nuclear Information System (INIS)

    Setlow, B.; Setlow, P.

    1988-01-01

    Loss of small, acid-soluble spore protein alpha reduced spore UV resistance 30- to 50-fold in Bacillus subtilis strains deficient in pyrimidine dimer repair, but gave only a 5- to 8-fold reduction in UV resistance in repair-proficient strains. However, both repair-proficient and -deficient spores lacking this protein had identical heat and gamma-radiation resistance

  18. Sequence analysis and identification of the pyrKDbF operon from Lactococcus lactis including a novel gene, pyrK, involved in pyrimidine biosynthesis

    DEFF Research Database (Denmark)

    Andersen, Paal Skytt; Martinussen, Jan; Hammer, Karin

    1996-01-01

    Three genes encoding enzymes involved in the biosynthesis of pyrimidines have been found to constitute an operon in Lactococcus lactis. Two of the genes are the well-known pyr genes pyrDb and pyrF, encoding dihydroorotate dehydrogenase and orotidine monophosphate decarboxylase, respectively....... The third gene encodes a protein which was shown to be necessary for the activity of the pyrDb-encoded dihydroorotate dehydrogenase; we propose to name the gene pyrK. The pyrK-encoded protein is homologous to a number of proteins which are involved in electron transfer. The lactococcal pyrKDbF operon...... is highly homologous to the corresponding part of the much-larger pyr operon of Bacillus subtilis. orf2, the pyrK homolog in B. subtilis, has also been shown to be necessary for pyrimidine biosynthesis (A.E. Kahler and R.L. Switzer, J. Bacteriol. 178:5013-5016, 1996). Four genes adjacent to the operon, i...

  19. Structure of the Hydrated Platinum(II) Ion And the Cis-Diammine-Platinum(II) Complex in Acidic Aqueous Solution: An EXAFS Study

    Energy Technology Data Exchange (ETDEWEB)

    Jalilehvand, F.; Laffin, L.J.

    2009-05-18

    Careful analysis of Pt L{sub 3}-edge extended X-ray absorption fine structure (EXAFS) spectra shows that the hydrated platinum(II) ion in acidic (HClO{sub 4}) aqueous solution binds four water molecules with the Pt-O bond distance 2.01(2) {angstrom} and one (or two) in the axial position at 2.39(2) {angstrom}. The weak axial water coordination is in accordance with the unexpectedly small activation volume previously reported for water exchange in an interchange mechanism with associative character. The hydrated cis-diammineplatinum(II) complex has a similar coordination environment with two ammine and two aqua ligands strongly bound with Pt-O/N bond distances of 2.01(2) {angstrom} and, in addition, one (or two) axial water molecule at 2.37(2) {angstrom}. This result provides a new basis for theoretical computational studies aiming to connect the function of the anticancer drug cis-platin to its ligand exchange reactions, where usually four-coordinated square planar platinum(II) species are considered as the reactant and product. {sup 195}Pt NMR spectroscopy has been used to characterize the Pt(II) complexes.

  20. Repair of closely opposed cyclobutyl pyrimidine dimers in UV-sensitive human diploid fibroblasts

    International Nuclear Information System (INIS)

    Lam, L.H.; Reynolds, R.J.

    1986-01-01

    An enzyme-sensitive site assay has been used to examine the fate of closely opposed pyrimidine dimers in fibroblasts from individuals afflicted with various genetic disorders that confer increased cellular sensitivity to UV radiation. The disappearance of bifilar enzyme-sensitive sites was found to be normal in cells from individuals with Fanconi's anemia, Cockayne's syndrome, dyskeratosis congenita and the variant form of xeroderma pigmentosum. The rate of bifilar enzyme-sensitive site removal in XP cells assigned to complementation group C was reduced by an amount similar to that observed for the repair of isolated dimers. Our results indicate that the initiation of repair at closely opposed dimers is slow in XP-C cells but normal in all other cells examined. (Auth.)

  1. Oxidation of 4-methoxy-1-naphthol on promoted platinum catalysts

    CSIR Research Space (South Africa)

    Maphoru, MV

    2017-07-01

    Full Text Available , July 2017, Volume 58, Issue 4, pp 441–447 Oxidation of 4-methoxy-1-naphthol on promoted platinum catalysts M. V. Maphoru J. Heveling S. Kesavan Pillai Abstract Oxidative coupling of naphthols is a useful method for the formation of new...

  2. In situ measurements of Merensky pillar behaviour at Impala Platinum

    CSIR Research Space (South Africa)

    Watson, BP

    2009-12-01

    Full Text Available to stabilize the stoping excavations. This paper describes the in situ measurement, of stress within a Merensky pillar from Impala Platinum. These measurements were used to derive a stress-strain curve that includes pre and post failure behaviour. 2D FLAC...

  3. Dynamic environmental transmission electron microscopy observation of platinum electrode catalyst deactivation in a proton-exchange-membrane fuel cell.

    Science.gov (United States)

    Yoshida, Kenta; Xudong, Zhang; Bright, Alexander N; Saitoh, Koh; Tanaka, Nobuo

    2013-02-15

    Spherical-aberration-corrected environmental transmission electron microscopy (AC-ETEM) was applied to study the catalytic activity of platinum/amorphous carbon electrode catalysts in proton-exchange-membrane fuel cells (PEMFCs). These electrode catalysts were characterized in different atmospheres, such as hydrogen and air, and a conventional high vacuum of 10(-5) Pa. A high-speed charge coupled device camera was used to capture real-time movies to dynamically study the diffusion and reconstruction of nanoparticles with an information transfer down to 0.1 nm, a time resolution below 0.2 s and an acceleration voltage of 300 kV. With such high spatial and time resolution, AC-ETEM permits the visualization of surface-atom behaviour that dominates the coalescence and surface-reconstruction processes of the nanoparticles. To contribute to the development of robust PEMFC platinum/amorphous carbon electrode catalysts, the change in the specific surface area of platinum particles was evaluated in hydrogen and air atmospheres. The deactivation of such catalysts during cycle operation is a serious problem that must be resolved for the practical use of PEMFCs in real vehicles. In this paper, the mechanism for the deactivation of platinum/amorphous carbon electrode catalysts is discussed using the decay rate of the specific surface area of platinum particles, measured first in a vacuum and then in hydrogen and air atmospheres for comparison.

  4. A Challenge to Improve High-Temperature Platinum Resistance Thermometer

    Science.gov (United States)

    Tanaka, Y.; Widiatmo, J. V.; Harada, K.; Kobayashi, T.; Yamazawa, K.

    2017-05-01

    High-temperature standard platinum resistance thermometers (HTSPRTs) are used to interpolate the international temperature scale of 1990 (ITS-90), especially for temperatures between the aluminum and the silver points. For this, long-term stability of the HTSPRT is essential. CHINO R800-3L type SPRT, which has a nominal resistance at the triple point of water (TPW) around 0.25 Ω , is the one developed earlier for the interpolation of the ITS-90 at this temperature range. Further development to this previous model has been carried out for the purpose of improving the thermal stability. The improvement was focused on reducing the effect coming from the difference in thermal expansion between platinum wire and the quartz frame on which the platinum wire is installed. New HTSPRTs were made by CHINO Corporation. Some series of tests were carried out at CHINO and at NMIJ. Initial tests after the HTSPRT fabrication were done at CHINO, where thermal cycles between 500°C and 980°C were applied to the HTSPRTs to see change in the resistances at the TPW (R_{TPW}) and at the gallium point (R_{Ga}). Repeated resistance measurements at the silver point (R_{Ag}) were performed after completing the thermal cycling test. Before and after every measurement at silver point, R_{TPW} was measured, while before and after every two silver point realization R_{Ga} were measured. After completing this test, the HTSPRTs were transported to NMIJ, where the same repeated measurements at the silver point were done at NMIJ. These were then repeated at CHINO and at NMIJ upon repeated transportation among the institutes, to evaluate some effect due to transportation. This paper reports the details of the above-mentioned tests, the results and the analysis.

  5. EFSA Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids (CEF); Scientific Opinion on Flavouring Group Evaluation 301 (FGE.301): A sulphur substituted pyrimidin-derivative and its hydrochloride salt

    DEFF Research Database (Denmark)

    Larsen, John Christian; Nørby, Karin Kristiane; Beltoft, Vibe Meister

    The Panel on Food Contact Materials, Enzymes, Flavourings and Processing Aids of the European Food Safety Authority was requested to evaluate two flavouring substances, 4-amino-5,6-dimethylthieno[2,3-d]pyrimidin-2(1H)-one [FL-no: 16.116] and 4-amino-5,6-dimethylthieno[2,3-d]pyrimidin-2(1H...... on structure-activity relationships, intake from current uses, toxicological threshold of concern, and available data on metabolism and toxicity. The Panel concluded that the two substances [FL-no: 16.116 and 16.120] do not give rise to safety concerns at their levels of dietary intake, estimated on the basis...

  6. Electrochemical behaviour of gamma hydroxybutyric acid at a platinum electrode in acidic medium

    International Nuclear Information System (INIS)

    Jiménez-Pérez, R.; Sevilla, J.M.; Pineda, T.; Blázquez, M.; González-Rodríguez, J.

    2013-01-01

    Highlights: • This is the first reported electrochemical study of the behaviour of GHB. • The first study of the interaction of GHB on solid electrodes. • The GHB oxidation process in platinum electrodes is a complex process. • Re-dissolution and reduction of Pt oxides and oxidation of the GHB OH group. • The oxidation process is also influenced by pH and GHB concentration. -- Abstract: The electrooxidation of gamma hydroxybutyric acid (GHB) on a polycrystalline platinum electrode is studied by cyclic voltammetry in acidic medium. Two oxidation peaks, A and B, are obtained in the positive scan within the potential range of the double layer region and of the platinum oxide region, respectively. In the negative going potential sweep an inverted oxidation peak with an onset partially overlapping with the tail of the cathodic peak for the reduction of the platinum oxide formed during the anodic scan is obtained (peak C). This inverted peak can be observed at a potential close to +0.2 V (vs Ag/AgCl at pH 2) and separated 0.4 and 0.8 V from the two other oxidation peaks obtained during the anodic scan and in such conditions that the surface is particularly activated to favour this electrochemical process. The response obtained in the electronic current for the different peaks when GHB concentration and scan rate were changed to allows inferring that these are the result of a potential dependent mechanism. The behaviour observed is according with the oxidation of the alcohol group to the corresponding aldehyde and carboxylic acid (succinic acid) as main products

  7. The Influence of Environmental Friendliness on Green Trust: The Mediation Effects of Green Satisfaction and Green Perceived Quality

    Directory of Open Access Journals (Sweden)

    Yu-Shan Chen

    2015-07-01

    Full Text Available As global green trends became more prevalent, green marketing also developed into an important issue. Although prior literature explored the main factors affecting green trust, it was inconclusive as to how environmental friendliness could affect the green trust in green marketing. This study aims to focus on the positive influence of environmental friendliness on green trust, and explore the mediation effects of green satisfaction and green perceived quality. This study undertakes an empirical study by means of questionnaire survey. The respondents are consumers who have experience purchasing green products. This study applies structural equation modeling (SEM to test the hypotheses. The findings of this study indicate that (1 environmental friendliness has a significant positive impact on green satisfaction, green perceived quality, and green trust; (2 both green satisfaction and green perceived quality positively affect green trust; and (3 green satisfaction and green perceived quality partially mediate the positive relationship between environmental friendliness and green trust.

  8. The influence of platinum washing-out time on its recovery from used auto catalytic converters

    Directory of Open Access Journals (Sweden)

    A. Fornalczyk

    2014-07-01

    Full Text Available The used catalytic converters contain small amounts of precious metals. Recovery of these metals is essential for environmental and economic reasons. This work presents a method of Platinum Group Metals (PGM recovery from auto catalytic converters in which they are washed out by a liquid metal. The magneto-hydro-dynamic pump was used to force circulation of liquid metal under the influence of electromagnetic fields The influence of process time on platinum recovery was also carried out.

  9. A Gene Expression Profile of BRCAness That Predicts for Responsiveness to Platinum and PARP Inhibitors

    Science.gov (United States)

    2017-02-01

    affecting the function of Fanconi Anemia (FA) genes ( FANCA /B/C/D2/E/F/G/I/J/L/M, PALB2) or DNA damage response genes involved in HR 5 (ATM, ATR...Award Number: W81XWH-10-1-0585 TITLE: A Gene Expression Profile of BRCAness That Predicts for Responsiveness to Platinum and PARP Inhibitors...To) 15 July 2010 – 2 Nov.2016 4. TITLE AND SUBTITLE A Gene Expression Profile of BRCAness That Predicts for Responsiveness to Platinum and PARP

  10. Mono(p-tolyl)platinum(II) and bis(p-tolyl)platinum(II) complexes of diethylsulfide as reagents for organoplatinum synthesis. Structures of [Pt(p-Tol)2(µ-SEt2)]2 and PtCl(p-Tol)(bpy) (bpy = 2,2'-bipyridine)

    NARCIS (Netherlands)

    Koten, G. van; Casado Lacabra, M.A.; Canty, A.J.; Lutz, M.H.; Patel, J.; Spek, A.L.; Sun, H.

    2001-01-01

    The complex trans-PtCl(p-Tol)(SEt{2}){2} is obtained from the reaction of [Pt(p-Tol){2}(SEt{2})]{2} with PtCl{2}(SEt{2}){2} and SEt{2} in mole ratio 1:2:2. The mono(p-tolyl)platinum(II) and bis(p-tolyl)platinum(II) complexes of diethylsulfide react with 2, 2'-bipyridine to form the complexes

  11. The determination, by atomic-absorption spectrophotometry using electrothermal atomization, of platinum, palladium, rhodium, ruthenium, and iridium

    International Nuclear Information System (INIS)

    Haines, J.; Robert, R.V.D.

    1982-01-01

    A method that involves measurement by atomic-absorption spectrophotometry using electrothermal atomization has been developed for the determination of trace quantities of platinum, palladium, rhodium, ruthenium, and iridium in mineralogical samples. The elements are separated and concentrated by fusion, nickel sulphide being used as the collector, and the analyte elements are measured in the resulting acid solution. An organic extraction procedure was found to offer no advantages over the proposed method. Mutual interferences between the five platinum-group metals examined, as well as interferences from gold, silver, and nickel were determined. The accuracy of the measurement was established by the analysis of a platinum-ore reference material. The lower limits of determination of each of the analyte elements in a sample material are as follows: platinum 1,6μg/l, palladium 0,2μg/1, rhodium 0,5μg/l, ruthenium 3μg/l, and iridium 2,5μg/l. The relative standard deviations range from 0,05 for rhodium to 0.08 for iridium. The method, which is described in detail in the Appendix, is applicable to the determination of these elements in ores, tailings, and geological materials in which the total concentration of the noble metals is less than 1g/t

  12. l-Glutamic acid assisted eco-friendly one-pot synthesis of sheet-assembled platinum-palladium alloy networks for methanol oxidation and oxygen reduction reactions.

    Science.gov (United States)

    Shi, Ya-Cheng; Mei, Li-Ping; Wang, Ai-Jun; Yuan, Tao; Chen, Sai-Sai; Feng, Jiu-Ju

    2017-10-15

    In this work, bimetallic platinum-palladium sheet-assembled alloy networks (PtPd SAANs) were facilely synthesized by an eco-friendly one-pot aqueous approach under the guidance of l-glutamic acid at room temperature, without any additive, seed, toxic or organic solvent involved. l-Glutamic acid was served as the green shape-director and weak-stabilizing agent. A series of characterization techniques were employed to examine the morphology, structure and formation mechanism of the product. The architectures exhibited improved electrocatalytic activity and durable ability toward methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) in contrast with commercial Pt black and Pd black catalysts. This is ascribed to the unique structures of the obtained PtPd SAANs and the synergistic effects of the bimetals. These results demonstrate the potential application of the prepared catalyst in fuel cells. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Stretches of alternating pyrimidine/purines and purines are respectively linked with pathogenicity and growth temperature in prokaryotes

    DEFF Research Database (Denmark)

    Ussery, David; Bohlin, J; Hardy, SP

    2009-01-01

    BACKGROUND: The genomic fractions of purine (RR) and alternating pyrimidine/purine (YR) stretches of 10 base pairs or more, have been linked to genomic AT content, the formation of different DNA helices, strand-biased gene distribution, DNA structure, and more. Although some of these factors are ...... phyla. RR stretches are overrepresented in all phyla except for the Actinobacteria and beta-Proteobacteria. In contrast, YR tracts are underrepresented in all phyla except for the beta-Proteobacterial group. YR-stretches are associated with phylum, pathogenicity and habitat, whilst RR...

  14. Enhancing the platinum atomic layer deposition infiltration depth inside anodic alumina nanoporous membrane

    Energy Technology Data Exchange (ETDEWEB)

    Vaish, Amit, E-mail: anv@udel.edu; Krueger, Susan; Dimitriou, Michael; Majkrzak, Charles [National Institute of Standards and Technology (NIST) Center for Neutron Research, Gaithersburg, MD 20899-8313 (United States); Vanderah, David J. [Institute for Bioscience and Biotechnology Research, NIST, Rockville, Maryland 20850 (United States); Chen, Lei, E-mail: lei.chen@nist.gov [NIST Center for Nanoscale Science and Technology, Gaithersburg, Maryland 20899-8313 (United States); Gawrisch, Klaus [Laboratory of Membrane Biochemistry and Biophysics, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, Maryland 20892 (United States)

    2015-01-15

    Nanoporous platinum membranes can be straightforwardly fabricated by forming a Pt coating inside the nanopores of anodic alumina membranes (AAO) using atomic layer deposition (ALD). However, the high-aspect-ratio of AAO makes Pt ALD very challenging. By tuning the process deposition temperature and precursor exposure time, enhanced infiltration depth along with conformal coating was achieved for Pt ALD inside the AAO templates. Cross-sectional scanning electron microscopy/energy dispersive x-ray spectroscopy and small angle neutron scattering were employed to analyze the Pt coverage and thickness inside the AAO nanopores. Additionally, one application of platinum-coated membrane was demonstrated by creating a high-density protein-functionalized interface.

  15. One-Pot Synthesis of Some New Pyrido[2,3-d]pyrimidine Derivatives Catalyzed by Sodium Lauryl Sulfate in Aqueous Media

    Directory of Open Access Journals (Sweden)

    Sheng-Hui Li

    2010-01-01

    Full Text Available A series of pyrido[2,3-d]pyrimidine derivatives were synthesized by the three-component reaction of aromatic aldehyde, malononitrile and 6-amino-4-hydroxy-2-mercaptopyrimidine catalyzed by sodium lauryl sulfate (SDS in aqueous media. It was interesting that further aromatization took place automatically. This method provides several advantages such as easier work-up, milder reaction conditions and environmental friendly.

  16. Selective inhibition by methoxyamine of the apurinic/apyrimidinic endonuclease activity associated with pyrimidine dimer-DNA glycosylases from Micrococcus luteus and bacteriophage T4

    International Nuclear Information System (INIS)

    Liuzzi, M.; Weinfeld, M.; Paterson, M.C.

    1987-01-01

    The UV endonucleases from Micrococcus luteus and bacteriophage T4 possess two catalytic activities specific for the site of cyclobutane pyrimidine dimers in UV-irradiated DNA: a DNA glycosylase that cleaves the 5'-glycosyl bond of the dimerized pyrimidines and an apurinic/apyrimidinic (AP) endonuclease that thereupon incises the phosphodiester bond 3' to the resulting apyrimidinic site. The authors have explored the potential use of methoxyamine, a chemical that reacts at neutral pH with AP sites in DNA, as a selective inhibitor of the AP endonuclease activities residing in the M. luteus and T4 enzymes. The presence of 50 mM methoxyamine during incubation of UV-treated, [ 3 H]thymine-labeled poly(dA) x poly(dT) with either enzyme preparation was found to protect completely the irradiated copolymer from endonucleolytic attack at dimer sites, as assayed by yield of acid-soluble radioactivity. In contrast, the dimer-DNA glycosylase activity of each enzyme remained fully functional, as monitored retrospectively by release of free thymine after either photochemical-(5 kJ/m 2 , 254 nm) or photoenzymic- (Escherichia coli photolyase plus visible light) induced reversal of pyrimidine dimers in the UV-damaged substrate. The data demonstrate that the inhibition of the strand-incision reaction arises because of chemical modification of the AP sites and is not due to inactivation of the enzyme by methoxyamine. The results, combined with earlier findings for 5'-acting AP endonucleases, strongly suggest that methoxyamine is a highly specific inhibitor of virtually all AP endonucleases, irrespective of their modes of action, and may therefore prove useful in a wide variety of DNA repair studies

  17. Green power certification: environmental and consumer protection benefits of the Green-e programme

    Energy Technology Data Exchange (ETDEWEB)

    Wingate, M.; Hamrin, J. [Center for Resource Solutions (United States); Rabago, K. [Rocky Mountain Inst. (United States); Wiser, R. [Lawrence Berkeley National Lab. (United States)

    2000-06-01

    This article gives details of the Green-e environmental certification programme which certifies electricity generated from renewable energy sources in the US. This first non-profit certification programme originally was set up for California, and has now spread to other regions. The objectives of the Green-e programme, the need for the electricity product to meet minimum criteria to qualify, marketer requirements, verification of product claims, administration of the programme, and the second year programme results are discussed. The way in which the Green-e programme fits in with other programmes such as those set up by the state and federal customer protection agencies to help consumers select environmentally superior power is described.

  18. Investigations of radiochemical methods for the platinum group metals for NAA

    International Nuclear Information System (INIS)

    Tredoux, M.

    A radiochemical procedure for the determination of the platinum group metals and gold is outlined in this report. The sample is irradiated, treated with acids and passed through anion-exchange columns before being determined by gamma spectrometry

  19. Study of the chemisorption and hydrogenation of propylene on platinum by temperature-programed desorption

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchiya, S.; Nakamura, M.; Yoshioka, N.

    1978-01-01

    Temperature-programed desorption (TPD) chromotograms of propylene adsorbed on platinum black in the absence or presence of hydrogen preadsorbed, admitted simultaneously, or admitted later, all showed four peaks at about 260/sup 0/ (A), 380/sup 0/ (B), 570/sup 0/ (C), and higher than 720/sup 0/K (D). Peaks A and B were identified as mixtures of propylene and propane, and peaks C and D were methane formed by thermal decomposition of the chemisorbed propylene during desorption. When nitrogen rather than helium was used as the carrier gas for the TPD, only delta-hydrogen was observed; this suggested that propylene was more strongly adsorbed on the platinum than hydrogen. Studies of the reactivities with propylene of the various types of chemisorbed hydrogen previously detected by TPD showed that propylene reacted with ..gamma..-hydrogen present on the surface in the form of hydrogen atoms chemisorbed on top of platinum atoms and with ..beta..-hydrogen, molecular hydrogen chemisorbed in a bridged form, but did not react with delta-hydrogen. Tables and graph.

  20. Area-selective atomic layer deposition of platinum using photosensitive polyimide

    NARCIS (Netherlands)

    Vervuurt, R.H.J.; Sharma, A.; Jiao, Y.; Kessels, W.M.M.; Bol, A.A.

    2016-01-01

    Area-selective atomic layer deposition (AS-ALD) of platinum (Pt) was studied using photosensitive polyimide as a masking layer. The polyimide films were prepared by spin-coating and patterned using photolithography. AS-ALD of Pt using poly(methyl-methacrylate) (PMMA) masking layers was used as a