WorldWideScience

Sample records for controlling fragmentation chemistry

  1. Magmatic and fragmentation controls on volcanic ash surface chemistry

    Science.gov (United States)

    Ayris, Paul M.; Diplas, Spyros; Damby, David E.; Hornby, Adrian J.; Cimarelli, Corrado; Delmelle, Pierre; Scheu, Bettina; Dingwell, Donald B.

    2016-04-01

    The chemical effects of silicate ash ejected by explosive volcanic eruptions on environmental systems are fundamentally mediated by ash particle surfaces. Ash surfaces are a composite product of magmatic properties and fragmentation mechanisms, as well as in-plume and atmospheric alteration processes acting upon those surfaces during and after the eruption. Recent attention has focused on the capacity of alteration processes to shape ash surfaces; most notably, several studies have utilised X-ray photoelectron spectroscopy (XPS), a technique probing the elemental composition and coordination state of atoms within the top 10 nm of ash surfaces, to identify patterns of elemental depletions and enrichments relative to bulk ash chemical composition. Under the presumption of surface and bulk equivalence, any disparities have been previously attributed to surface alteration processes, but the ubiquity of some depletions (e.g., Ca, Fe) across multiple ash studies, irrespective of eruptive origin, could suggest these to be features of the surface produced at the instant of magma fragmentation. To investigate this possibility further, we conducted rapid decompression experiments at different pressure conditions and at ambient and magmatic temperature on porous andesitic rocks. These experiments produced fragmented ash material untouched by secondary alteration, which were compared to particles produced by crushing of large clasts from the same experiments. We investigated a restricted size fraction (63-90 μm) from both fragmented and crushed materials, determining bulk chemistry and mineralogy via XRF, SEM-BSE and EPMA, and investigated the chemical composition of the ash surface by XPS. Analyses suggest that fragmentation under experimental conditions partitioned a greater fraction of plagioclase-rich particles into the selected size fraction, relative to particles produced by crushing. Trends in surface chemical composition in fragmented and crushed particles mirror that

  2. The multiple roles of computational chemistry in fragment-based drug design

    Science.gov (United States)

    Law, Richard; Barker, Oliver; Barker, John J.; Hesterkamp, Thomas; Godemann, Robert; Andersen, Ole; Fryatt, Tara; Courtney, Steve; Hallett, Dave; Whittaker, Mark

    2009-08-01

    Fragment-based drug discovery (FBDD) represents a change in strategy from the screening of molecules with higher molecular weights and physical properties more akin to fully drug-like compounds, to the screening of smaller, less complex molecules. This is because it has been recognised that fragment hit molecules can be efficiently grown and optimised into leads, particularly after the binding mode to the target protein has been first determined by 3D structural elucidation, e.g. by NMR or X-ray crystallography. Several studies have shown that medicinal chemistry optimisation of an already drug-like hit or lead compound can result in a final compound with too high molecular weight and lipophilicity. The evolution of a lower molecular weight fragment hit therefore represents an attractive alternative approach to optimisation as it allows better control of compound properties. Computational chemistry can play an important role both prior to a fragment screen, in producing a target focussed fragment library, and post-screening in the evolution of a drug-like molecule from a fragment hit, both with and without the available fragment-target co-complex structure. We will review many of the current developments in the area and illustrate with some recent examples from successful FBDD discovery projects that we have conducted.

  3. Fragment-to-Lead Medicinal Chemistry Publications in 2015.

    Science.gov (United States)

    Johnson, Christopher N; Erlanson, Daniel A; Murray, Christopher W; Rees, David C

    2017-01-12

    Fragment-based drug discovery (FBDD) is now well-established as a technology for generating new chemical leads and drugs. This Miniperspective provides a tabulated overview of the fragment-to-lead literature published in the year 2015, together with a commentary on trends observed across the FBDD field during this time. It is hoped that this tabulated summary will provide a useful point of reference for both FBDD practitioners and the wider medicinal chemistry community.

  4. Fragment Linking and Optimization of Inhibitors of the Aspartic Protease Endothiapepsin : Fragment-Based Drug Design Facilitated by Dynamic Combinatorial Chemistry

    NARCIS (Netherlands)

    Mondal, Milon; Radeva, Nedyalka; Fanlo-Virgos, Hugo; Otto, Sijbren; Klebe, Gerhard; Hirsch, Anna K. H.

    2016-01-01

    Fragment-based drug design (FBDD) affords active compounds for biological targets. While there are numerous reports on FBDD by fragment growing/optimization, fragment linking has rarely been reported. Dynamic combinatorial chemistry (DCC) has become a powerful hit-identification strategy for

  5. Controlled fragmentation

    International Nuclear Information System (INIS)

    Arnold, Werner

    2002-01-01

    Contrary to natural fragmentation, controlled fragmentation offers the possibility to adapt fragment parameters like size and mass to the performance requirements in a very flexible way. Known mechanisms like grooves inside the casing, weaken the structure. This is, however, excluded for applications with high accelerations during launch or piercing requirements for example on a semi armor piercing penetrator. Another method to achieve controlled fragmentation with an additional grid layer is presented with which the required grooves are produced 'just in time' inside the casing during detonation of the high explosive. The process of generating the grooves aided by the grid layer was studied using the hydrocode HULL with respect to varying grid designs and material combinations. Subsequent to this, a large range of these theoretically investigated combinations was contemplated in substantial experimental tests. With an optimised grid design and a suitable material selection, the controlled fragment admits a very flexible adaptation to the set requirements. Additional advantages like the increase of perforation performance or incendiary amplification can be realized with the grid layer

  6. The Fragment Network: A Chemistry Recommendation Engine Built Using a Graph Database.

    Science.gov (United States)

    Hall, Richard J; Murray, Christopher W; Verdonk, Marcel L

    2017-07-27

    The hit validation stage of a fragment-based drug discovery campaign involves probing the SAR around one or more fragment hits. This often requires a search for similar compounds in a corporate collection or from commercial suppliers. The Fragment Network is a graph database that allows a user to efficiently search chemical space around a compound of interest. The result set is chemically intuitive, naturally grouped by substitution pattern and meaningfully sorted according to the number of observations of each transformation in medicinal chemistry databases. This paper describes the algorithms used to construct and search the Fragment Network and provides examples of how it may be used in a drug discovery context.

  7. Fragment Linking and Optimization of Inhibitors of the Aspartic Protease Endothiapepsin: Fragment-Based Drug Design Facilitated by Dynamic Combinatorial Chemistry.

    Science.gov (United States)

    Mondal, Milon; Radeva, Nedyalka; Fanlo-Virgós, Hugo; Otto, Sijbren; Klebe, Gerhard; Hirsch, Anna K H

    2016-08-01

    Fragment-based drug design (FBDD) affords active compounds for biological targets. While there are numerous reports on FBDD by fragment growing/optimization, fragment linking has rarely been reported. Dynamic combinatorial chemistry (DCC) has become a powerful hit-identification strategy for biological targets. We report the synergistic combination of fragment linking and DCC to identify inhibitors of the aspartic protease endothiapepsin. Based on X-ray crystal structures of endothiapepsin in complex with fragments, we designed a library of bis-acylhydrazones and used DCC to identify potent inhibitors. The most potent inhibitor exhibits an IC50 value of 54 nm, which represents a 240-fold improvement in potency compared to the parent hits. Subsequent X-ray crystallography validated the predicted binding mode, thus demonstrating the efficiency of the combination of fragment linking and DCC as a hit-identification strategy. This approach could be applied to a range of biological targets, and holds the potential to facilitate hit-to-lead optimization. © 2016 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  8. Advanced chemistry management system to optimize BWR chemistry control

    International Nuclear Information System (INIS)

    Maeda, K.; Nagasawa, K.

    2002-01-01

    BWR plant chemistry control has close relationships among nuclear safety, component reliability, radiation field management and fuel integrity. Advanced technology is required to improve chemistry control [1,3,6,7,10,11]. Toshiba has developed TACMAN (Toshiba Advanced Chemistry Management system) to support BWR chemistry control. The TACMAN has been developed as response to utilities' years of requirements to keep plant operation safety, reliability and cost benefit. The advanced technology built into the TACMAN allows utilities to make efficient chemistry control and to keep cost benefit. TACMAN is currently being used in response to the needs for tools those plant chemists and engineers could use to optimize and identify plant chemistry conditions continuously. If an incipient condition or anomaly is detected at early stage, root causes evaluation and immediate countermeasures can be provided. Especially, the expert system brings numerous and competitive advantages not only to improve plant chemistry reliability but also to standardize and systematize know-how, empirical knowledge and technologies in BWR chemistry This paper shows detail functions of TACMAN and practical results to evaluate actual plant. (authors)

  9. Coordination Chemistry of Linear Oligopyrrolic Fragments Inspired by Heme Metabolites

    Science.gov (United States)

    Gautam, Ritika

    Linear oligopyrroles are degradation products of heme, which is converted in the presence of heme oxygenase to bile pigments, such as biliverdin and bilirubin. These tetrapyrrolic oligopyrroles are ubiquitously present in biological systems and find applications in the fields of catalysis and sensing. These linear tetrapyrrolic scaffolds are further degraded into linear tripyrrolic and dipyrrolic fragments. Although these lower oligopyrroles are abundantly present, their coordination chemistry requires further characterization. This dissertation focuses mainly on two classes of bioinspired linear oligopyrroles, propentdyopent and tripyrrindione, and their transition metal complexes, which present a rich ligand-based redox chemistry. Chapter 1 offers an overview of heme degradation to different classes of linear oligopyrroles and properties of their transition metal complexes. Chapter 2 is focused on the tripyrrin-1,14-dione scaffold of the urinary pigment uroerythrin, which coordinates divalent transition metals palladium and copper with square planar geometry. Specifically, the tripyrrin-1, 14-dione ligand binds Cu(II) and Pd(II) as a dianionic organic radical under ambient conditions. The electrochemical study confirms the presence of ligand based redox chemistry, and one electron oxidation or reduction reactions do not alter the planar geometry around the metal center. The X-Ray analysis and the electron paramagnetic resonance (EPR) studies of the complexes in the solid and solution phase reveals intermolecular interactions between the ligand based unpaired electrons and therefore formation of neutral pi-pi dimers. In Chapter 3, the antioxidant activity and the fluorescence sensor properties of the tripyrrin-1,14-dione ligand in the presence of superoxide are described. We found that the tripyrrindione ligand undergoes one-electron reduction in the presence of the superoxide radical anion (O2•- ) to form highly fluorescent H3TD1•- radical anion, which emits

  10. Rock fragmentation control in opencast blasting

    Directory of Open Access Journals (Sweden)

    P.K. Singh

    2016-04-01

    Full Text Available The blasting operation plays a pivotal role in the overall economics of opencast mines. The blasting sub-system affects all the other associated sub-systems, i.e. loading, transport, crushing and milling operations. Fragmentation control through effective blast design and its effect on productivity are the challenging tasks for practicing blasting engineer due to inadequate knowledge of actual explosive energy released in the borehole, varying initiation practice in blast design and its effect on explosive energy release characteristic. This paper describes the result of a systematic study on the impact of blast design parameters on rock fragmentation at three mines in India. The mines use draglines and shovel–dumper combination for removal of overburden. Despite its pivotal role in controlling the overall economics of a mining operation, the expected blasting performance is often judged almost exclusively on the basis of poorly defined parameters such as powder factor and is often qualitative which results in very subjective assessment of blasting performance. Such an approach is very poor substitutes for accurate assessment of explosive and blasting performance. Ninety one blasts were conducted with varying blast designs and charging patterns, and their impacts on the rock fragmentation were documented. A high-speed camera was deployed to record the detonation sequences of the blasts. The efficiency of the loading machines was also correlated with the mean fragment size obtained from the fragmentation analyses.

  11. Fragment Linking and Optimization of Inhibitors of the Aspartic Protease Endothiapepsin: Fragment‐Based Drug Design Facilitated by Dynamic Combinatorial Chemistry

    Science.gov (United States)

    Mondal, Milon; Radeva, Nedyalka; Fanlo‐Virgós, Hugo; Otto, Sijbren; Klebe, Gerhard

    2016-01-01

    Abstract Fragment‐based drug design (FBDD) affords active compounds for biological targets. While there are numerous reports on FBDD by fragment growing/optimization, fragment linking has rarely been reported. Dynamic combinatorial chemistry (DCC) has become a powerful hit‐identification strategy for biological targets. We report the synergistic combination of fragment linking and DCC to identify inhibitors of the aspartic protease endothiapepsin. Based on X‐ray crystal structures of endothiapepsin in complex with fragments, we designed a library of bis‐acylhydrazones and used DCC to identify potent inhibitors. The most potent inhibitor exhibits an IC50 value of 54 nm, which represents a 240‐fold improvement in potency compared to the parent hits. Subsequent X‐ray crystallography validated the predicted binding mode, thus demonstrating the efficiency of the combination of fragment linking and DCC as a hit‐identification strategy. This approach could be applied to a range of biological targets, and holds the potential to facilitate hit‐to‐lead optimization. PMID:27400756

  12. [Fragment-based drug discovery: concept and aim].

    Science.gov (United States)

    Tanaka, Daisuke

    2010-03-01

    Fragment-Based Drug Discovery (FBDD) has been recognized as a newly emerging lead discovery methodology that involves biophysical fragment screening and chemistry-driven fragment-to-lead stages. Although fragments, defined as structurally simple and small compounds (typically FBDD primarily turns our attention to weakly but specifically binding fragments (hit fragments) as the starting point of medicinal chemistry. Hit fragments are then promoted to more potent lead compounds through linking or merging with another hit fragment and/or attaching functional groups. Another positive aspect of FBDD is ligand efficiency. Ligand efficiency is a useful guide in screening hit selection and hit-to-lead phases to achieve lead-likeness. Owing to these features, a number of successful applications of FBDD to "undruggable targets" (where HTS and other lead identification methods failed to identify useful lead compounds) have been reported. As a result, FBDD is now expected to complement more conventional methodologies. This review, as an introduction of the following articles, will summarize the fundamental concepts of FBDD and will discuss its advantages over other conventional drug discovery approaches.

  13. Effective Fragmentation and Flyrock Control Strategies at Quarries

    Directory of Open Access Journals (Sweden)

    Sedat Esen

    2017-01-01

    Full Text Available This paper presents the effective fragmentation and flyrock control strategies that could be applied at quarries to improve the productivity and safety. Fragmentation measurement and modelling as well as a comprehensive drill and blast audit are essential for improving the fragmentation. Face profiling and bore tracking are good tools to manage the ―as-designed‖ and ―as-drilled‖ conditions to get reasonable fragmentation from face burden zone and minimise the flyrock risk. In general, a large scatter in fragmentation data was observed at sites and the causes should be analysed by a detailed root-cause analysis technique. Two case studies were presented in this paper showing some of the effective fragmentation strategies. Finally, a flyrock model was shown to determine the safe blast exclusion zone for the mining equipment and personnel. Some key guidelines were suggested to minimise the occurrence of the flyrock.

  14. Anatomy of a cluster IDP. Part 2: Noble gas abundances, trace element geochemistry, isotopic abundances, and trace organic chemistry of several fragments from L2008#5

    Science.gov (United States)

    Thomas, K. L.; Clemett, S. J.; Flynn, G. J.; Keller, L. P.; Mckay, David S.; Messenger, S.; Nier, A. O.; Schlutter, D. J.; Sutton, S. R.; Walker, R. M.

    1994-01-01

    The topics discussed include the following: noble gas content and release temperatures; trace element abundances; heating summary of cluster fragments; isotopic measurements; and trace organic chemistry.

  15. A probabilistic approach to controlling crevice chemistry

    International Nuclear Information System (INIS)

    Millett, P.J.; Brobst, G.E.; Riddle, J.

    1995-01-01

    It has been generally accepted that the corrosion of steam generator tubing could be reduced if the local pH in regions where impurities concentrate could be controlled. The practice of molar ratio control is based on this assumption. Unfortunately, due to the complexity of the crevice concentration process, efforts to model the crevice chemistry based on bulk water conditions are quite uncertain. In-situ monitoring of the crevice chemistry is desirable, but may not be achievable in the near future. The current methodology for assessing the crevice chemistry is to monitor the hideout return chemistry when the plant shuts down. This approach also has its shortcomings, but may provide sufficient data to evaluate whether the crevice pH is in a desirable range. In this paper, an approach to controlling the crevice chemistry based on a target molar ratio indicator is introduced. The molar ratio indicator is based on what is believed to be the most reliable hideout return data. Probabilistic arguments are then used to show that the crevice pH will most likely be in a desirable range when the target molar ratio is achieved

  16. Structures of endothiapepsin-fragment complexes from crystallographic fragment screening using a novel, diverse and affordable 96-compound fragment library.

    Science.gov (United States)

    Huschmann, Franziska U; Linnik, Janina; Sparta, Karine; Ühlein, Monika; Wang, Xiaojie; Metz, Alexander; Schiebel, Johannes; Heine, Andreas; Klebe, Gerhard; Weiss, Manfred S; Mueller, Uwe

    2016-05-01

    Crystallographic screening of the binding of small organic compounds (termed fragments) to proteins is increasingly important for medicinal chemistry-oriented drug discovery. To enable such experiments in a widespread manner, an affordable 96-compound library has been assembled for fragment screening in both academia and industry. The library is selected from already existing protein-ligand structures and is characterized by a broad ligand diversity, including buffer ingredients, carbohydrates, nucleotides, amino acids, peptide-like fragments and various drug-like organic compounds. When applied to the model protease endothiapepsin in a crystallographic screening experiment, a hit rate of nearly 10% was obtained. In comparison to other fragment libraries and considering that no pre-screening was performed, this hit rate is remarkably high. This demonstrates the general suitability of the selected compounds for an initial fragment-screening campaign. The library composition, experimental considerations and time requirements for a complete crystallographic fragment-screening campaign are discussed as well as the nine fully refined obtained endothiapepsin-fragment structures. While most of the fragments bind close to the catalytic centre of endothiapepsin in poses that have been observed previously, two fragments address new sites on the protein surface. ITC measurements show that the fragments bind to endothiapepsin with millimolar affinity.

  17. Structures of endothiapepsin–fragment complexes from crystallographic fragment screening using a novel, diverse and affordable 96-compound fragment library

    Science.gov (United States)

    Huschmann, Franziska U.; Linnik, Janina; Sparta, Karine; Ühlein, Monika; Wang, Xiaojie; Metz, Alexander; Schiebel, Johannes; Heine, Andreas; Klebe, Gerhard; Weiss, Manfred S.; Mueller, Uwe

    2016-01-01

    Crystallographic screening of the binding of small organic compounds (termed fragments) to proteins is increasingly important for medicinal chemistry-oriented drug discovery. To enable such experiments in a widespread manner, an affordable 96-compound library has been assembled for fragment screening in both academia and industry. The library is selected from already existing protein–ligand structures and is characterized by a broad ligand diversity, including buffer ingredients, carbohydrates, nucleotides, amino acids, peptide-like fragments and various drug-like organic compounds. When applied to the model protease endothiapepsin in a crystallographic screening experiment, a hit rate of nearly 10% was obtained. In comparison to other fragment libraries and considering that no pre-screening was performed, this hit rate is remarkably high. This demonstrates the general suitability of the selected compounds for an initial fragment-screening campaign. The library composition, experimental considerations and time requirements for a complete crystallographic fragment-screening campaign are discussed as well as the nine fully refined obtained endothiapepsin–fragment structures. While most of the fragments bind close to the catalytic centre of endothiapepsin in poses that have been observed previously, two fragments address new sites on the protein surface. ITC measurements show that the fragments bind to endothiapepsin with millimolar affinity. PMID:27139825

  18. Fragment-to-Lead Medicinal Chemistry Publications in 2016.

    Science.gov (United States)

    Johnson, Christopher N; Erlanson, Daniel A; Jahnke, Wolfgang; Mortenson, Paul N; Rees, David C

    2018-03-08

    The popularity of fragment-based drug discovery (FBDD) is demonstrated by the number of recent successful fragment-to-lead (F2L) publications. This Miniperspective provides a tabulated summary of the F2L literature published in the year 2016, along with discussion of general trends. It uses the same format as our summary of the 2015 literature and is intended to be a resource for both FBDD practitioners and medicinal chemists in general.

  19. Electrolyte chemistry control in electrodialysis processing

    Science.gov (United States)

    Hayes, Thomas D.; Severin, Blaine F.

    2017-12-26

    Methods for controlling electrolyte chemistry in electrodialysis units having an anode and a cathode each in an electrolyte of a selected concentration and a membrane stack disposed therebetween. The membrane stack includes pairs of cationic selective and anionic membranes to segregate increasingly dilute salts streams from concentrated salts stream. Electrolyte chemistry control is via use of at least one of following techniques: a single calcium exclusionary cationic selective membrane at a cathode cell boundary, an exclusionary membrane configured as a hydraulically isolated scavenger cell, a multivalent scavenger co-electrolyte and combinations thereof.

  20. Fragment library design: using cheminformatics and expert chemists to fill gaps in existing fragment libraries.

    Science.gov (United States)

    Kutchukian, Peter S; So, Sung-Sau; Fischer, Christian; Waller, Chris L

    2015-01-01

    Fragment based screening (FBS) has emerged as a mainstream lead discovery strategy in academia, biotechnology start-ups, and large pharma. As a prerequisite of FBS, a structurally diverse library of fragments is desirable in order to identify chemical matter that will interact with the range of diverse target classes that are prosecuted in contemporary screening campaigns. In addition, it is also desirable to offer synthetically amenable starting points to increase the probability of a successful fragment evolution through medicinal chemistry. Herein we describe a method to identify biologically relevant chemical substructures that are missing from an existing fragment library (chemical gaps), and organize these chemical gaps hierarchically so that medicinal chemists can efficiently navigate the prioritized chemical space and subsequently select purchasable fragments for inclusion in an enhanced fragment library.

  1. Fragmentation of pure and hydrated clusters of 5Br-uracil by low energy carbon ions: observation of hydrated fragments

    Czech Academy of Sciences Publication Activity Database

    Castrovilli, M. C.; Markush, P.; Bolognesi, P.; Rousseau, P.; Maclot, S.; Cartoni, A.; Delaunay, R.; Domaracka, A.; Kočišek, Jaroslav; Huber, B. A.; Avaldi, L.

    2017-01-01

    Roč. 19, č. 30 (2017), s. 19807-19814 ISSN 1463-9076 Institutional support: RVO:61388955 Keywords : fragmentation * nano-hydrated 5BrU clusters * low energy carbon ions Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 4.123, year: 2016

  2. Generation of Polar Semi-Saturated Bicyclic Pyrazoles for Fragment-Based Drug Discovery Campaigns.

    Science.gov (United States)

    Luise, Nicola; Wyatt, Paul

    2018-05-07

    Synthesising polar semi-saturated bicyclic heterocycles can lead to better starting points for fragment-based drug discovery (FBDD) programs. This communication highlights the application of diverse chemistry to construct bicyclic systems from a common intermediate, where pyrazole, a privileged heteroaromatic able to bind effectively to biological targets, is fused to diverse saturated counterparts. The generated fragments can be further developed either after confirmation of their binding pose or early in the process, as their synthetic intermediates. Essential quality control (QC) for selection of small molecules to add to a fragment library is discussed. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Searching Fragment Spaces with feature trees.

    Science.gov (United States)

    Lessel, Uta; Wellenzohn, Bernd; Lilienthal, Markus; Claussen, Holger

    2009-02-01

    Virtual combinatorial chemistry easily produces billions of compounds, for which conventional virtual screening cannot be performed even with the fastest methods available. An efficient solution for such a scenario is the generation of Fragment Spaces, which encode huge numbers of virtual compounds by their fragments/reagents and rules of how to combine them. Similarity-based searches can be performed in such spaces without ever fully enumerating all virtual products. Here we describe the generation of a huge Fragment Space encoding about 5 * 10(11) compounds based on established in-house synthesis protocols for combinatorial libraries, i.e., we encode practically evaluated combinatorial chemistry protocols in a machine readable form, rendering them accessible to in silico search methods. We show how such searches in this Fragment Space can be integrated as a first step in an overall workflow. It reduces the extremely huge number of virtual products by several orders of magnitude so that the resulting list of molecules becomes more manageable for further more elaborated and time-consuming analysis steps. Results of a case study are presented and discussed, which lead to some general conclusions for an efficient expansion of the chemical space to be screened in pharmaceutical companies.

  4. Attosecond-recollision-controlled selective fragmentation of polyatomic molecules.

    Science.gov (United States)

    Xie, Xinhua; Doblhoff-Dier, Katharina; Roither, Stefan; Schöffler, Markus S; Kartashov, Daniil; Xu, Huailiang; Rathje, Tim; Paulus, Gerhard G; Baltuška, Andrius; Gräfe, Stefanie; Kitzler, Markus

    2012-12-14

    Control over various fragmentation reactions of a series of polyatomic molecules (acetylene, ethylene, 1,3-butadiene) by the optical waveform of intense few-cycle laser pulses is demonstrated experimentally. We show both experimentally and theoretically that the responsible mechanism is inelastic ionization from inner-valence molecular orbitals by recolliding electron wave packets, whose recollision energy in few-cycle ionizing laser pulses strongly depends on the optical waveform. Our work demonstrates an efficient and selective way of predetermining fragmentation and isomerization reactions in polyatomic molecules on subfemtosecond time scales.

  5. Control of water chemistry in operating reactors

    International Nuclear Information System (INIS)

    Riess, R.

    1997-01-01

    Water chemistry plays a major role in fuel cladding corrosion and hydriding. Although a full understanding of all mechanisms involved in cladding corrosion does not exist, controlling the water chemistry has achieved quite some progress in recent years. As an example, in PWRs the activity transport is controlled by operating the coolant under higher pH-values (i.e. the ''modified'' B/Li-Chemistry). On the other hand, the lithium concentration is limited to a maximum value of 2 ppm in order to avoid an acceleration of the fuel cladding corrosion. In BWR plants, for example, the industry has learned on how to limit the copper concentration in the feedwater in order to limit CILC (Copper Induced Localized Corrosion) on the fuel cladding. However, economic pressures are leading to more rigorous operating conditions in power reactors. Fuel burnups are to be increased, higher efficiencies are to be achieved, by running at higher temperatures, plant lifetimes are to be extended. In summary, this paper will describe the state of the art in controlling water chemistry in operating reactors and it will give an outlook on potential problems that will arise when going to more severe operating conditions. (author). 3 figs, 6 tabs

  6. Control of water chemistry in operating reactors

    Energy Technology Data Exchange (ETDEWEB)

    Riess, R [Siemens AG Unternehmensbereich KWU, Erlangen (Germany)

    1997-02-01

    Water chemistry plays a major role in fuel cladding corrosion and hydriding. Although a full understanding of all mechanisms involved in cladding corrosion does not exist, controlling the water chemistry has achieved quite some progress in recent years. As an example, in PWRs the activity transport is controlled by operating the coolant under higher pH-values (i.e. the ``modified`` B/Li-Chemistry). On the other hand, the lithium concentration is limited to a maximum value of 2 ppm in order to avoid an acceleration of the fuel cladding corrosion. In BWR plants, for example, the industry has learned on how to limit the copper concentration in the feedwater in order to limit CILC (Copper Induced Localized Corrosion) on the fuel cladding. However, economic pressures are leading to more rigorous operating conditions in power reactors. Fuel burnups are to be increased, higher efficiencies are to be achieved, by running at higher temperatures, plant lifetimes are to be extended. In summary, this paper will describe the state of the art in controlling water chemistry in operating reactors and it will give an outlook on potential problems that will arise when going to more severe operating conditions. (author). 3 figs, 6 tabs.

  7. Threshold Switching Induced by Controllable Fragmentation in Silver Nanowire Networks.

    Science.gov (United States)

    Wan, Tao; Pan, Ying; Du, Haiwei; Qu, Bo; Yi, Jiabao; Chu, Dewei

    2018-01-24

    Silver nanowire (Ag NW) networks have been widely studied because of a great potential in various electronic devices. However, nanowires usually undergo a fragmentation process at elevated temperatures due to the Rayleigh instability that is a result of reduction of surface/interface energy. In this case, the nanowires become completely insulating due to the formation of randomly distributed Ag particles with a large distance and further applications are hindered. Herein, we demonstrate a novel concept based on the combination of ultraviolet/ozone irradiation and a low-temperature annealing process to effectively utilize and control the fragmentation behavior to realize the resistive switching performances. In contrast to the conventional fragmentation, the designed Ag/AgO x interface facilitates a unique morphology of short nanorod-like segments or chains of tiny Ag nanoparticles with a very small spacing distance, providing conduction paths for achieving the tunneling process between the isolated fragments under the electric field. On the basis of this specific morphology, the Ag NW network has a tunable resistance and shows volatile threshold switching characteristics with a high selectivity, which is the ON/OFF current ratio in selector devices. Our concept exploits a new function of Ag NW network, i.e., resistive switching, which can be developed by designing a controllable fragmentation.

  8. Automated Water Chemistry Control at University of Virginia Pools.

    Science.gov (United States)

    Krone, Dan

    1997-01-01

    Describes the technologically advanced aquatic and fitness center at the University of Virginia. Discusses the imprecise water chemistry control at the former facility and its intensive monitoring requirements. Details the new chemistry control standards initiated in the new center, which ensure constant chlorine and pH levels. (RJM)

  9. When fragments link : a bibliometric perspective on the development of fragment-based drug discovery

    NARCIS (Netherlands)

    Romasanta, A.K.S.; van der Sijde, P.C.; Hellsten, I.; Hubbard, Roderick E.; Keseru, Gyorgy M.; van Muijlwijk-Koezen, Jacqueline E.; de Esch, I.J.P.

    2018-01-01

    Fragment-based drug discovery (FBDD) is a highly interdisciplinary field, rich in ideas integrated from pharmaceutical sciences, chemistry, biology, and physics, among others. To enrich our understanding of the development of the field, we used bibliometric techniques to analyze 3642 publications in

  10. Advances in water chemistry control for BWRs and PWRs

    International Nuclear Information System (INIS)

    Wood, C.J.

    1997-01-01

    This paper is an overview of the effects of water chemistry developments on the current operation of nuclear power plants in the United States, and the mitigation of corrosion-related degradation processes and radiation field build-up processes through the use of advanced water chemistry. Recent modifications in water chemistry to control and reduce radiation fields are outlined, including revisions to the EPRI water chemistry guidelines for BWRs and PWR primary and secondary systems. The change from a single water chemistry specification for all plants to a set of options, from which a plant-specific chemistry programme can be defined, is described. (author)

  11. Water chemistry control at FBTR

    International Nuclear Information System (INIS)

    Panigrahi, B.S.; Jambunathan, D.; Suresh Kumar, K.V.; Ramanathan, V.; Srinivasan, G.; Ramalingam, P.V.

    2008-01-01

    Condenser cooling and service water systems together serve as the cooling water system of Fast Breeder Test Reactor (FBTR). Palar river water serves as the make-up to the cooling water system. Initially, the service water system alone was commissioned in phases depending upon the arrival of auxiliary equipments at site. During this period, the water was not treated chemically and it also inadvertently remained stagnant for some time in some systems. Thereafter, a threshold chemical treatment was started. However, pin-hole leaks and reduced flow through the heat exchangers were observed and therefore chemical cleaning of headers was done and small diameter pipelines were replaced. Following this a full fledged chemistry control with proprietary formulations was initiated. Later the condenser cooling system was commissioned and the chemical treatment was reviewed. With adoption of improved monitoring methodology and treatment formulation satisfactory corrosion control (< 3 mpy) with minimum deposition problem in this system could be achieved. The primary coolant (primary sodium) of FBTR transfers the nuclear heat to the secondary coolant (secondary sodium) that in turn transfers heat to water in Once Through Steam Generator (OTSG) to generate superheated steam (480 deg C at 125 bar). Efficient water chemistry control plays the vital role in minimizing corrosion related failures of steam generator tubes and ensuring steam generator tube integrity. Therefore, the technical specifications of chemistry parameters of feed/steam water at FBTR are made very stringent to maintain the purity of water at the best attainable level. To meet this stringent feed water and steam quality specifications, online monitoring techniques have been employed in the steam/water circuit to get continuous information about the purity. These monitors have helped significantly in achieving the required feed water quality and running the steam generator for more than 25000 hours without any tube

  12. Phthalocyanides sensitized fragmentation of proteins

    Czech Academy of Sciences Publication Activity Database

    Klementová, S.; Tothová, D.; Revaková, R.; Kasková, M.; Wagnerová, Dana Marie

    2001-01-01

    Roč. 5, č. 1 (2001), s. 13-18 ISSN 0972-0626 R&D Projects: GA ČR GA203/96/1322 Institutional research plan: CEZ:AV0Z4032918 Keywords : phthalocyanides * photosensitied fragmentation of proteins Subject RIV: CA - Inorganic Chemistry

  13. Coherent control of indirect photofragmentation in the weak-field limit: Control of transient fragment distributions

    DEFF Research Database (Denmark)

    Shu, Chuan-Cun; Henriksen, Niels Engholm

    2011-01-01

    I molecule, where it is shown that the probability of observing atomic fragments as well as the distribution of their relative momenta can be changed by a phase modulated pulse with a fixed bandwidth. This type of control is restricted to finite times during the indirect fragmentation. (C) 2011 American...

  14. Recent experience in water chemistry control at PWR plants

    International Nuclear Information System (INIS)

    Makino, Ichiro

    2000-01-01

    At present, 23 units of PWRs are under operation in all of Japan, among which 11 units are operated by the Kansai Electric Power Co., Inc. (KEP). Plant availability in KEP's PWRs has been improved for the past several years, through their successive stable operation. Recently, a focus is given not only to maintenance of plant integrity, but also to preventive maintenance and water chemistry control. Various measures have been carried out to enhance exposure reduction of the primary water chemistry control in the Japanese PWRs. As a result, environmental dose equivalent rate is decreasing. A secondary system is now under excellent condition because of application of diversified measures for prevention of the SG tube corrosion. At present, the water chemistry control measures which take into account of efficient chemistry control and plant aging deterioration prevention, are being examined to use for both primary and secondary systems in Japanese PWRs, to further enhance their plant integrity and availability. And, some of them are currently being actually applied. (G.K.)

  15. Chemistry control challenges in a supercritical water-cooled reactor

    International Nuclear Information System (INIS)

    Guzonas, David; Tremaine, Peter; Jay-Gerin, Jean-Paul

    2009-01-01

    The long-term viability of a supercritical water-cooled reactor (SCWR) will depend on the ability of designers to predict and control water chemistry to minimize corrosion and the transport of corrosion products and radionuclides. Meeting this goal requires an enhanced understanding of water chemistry as the temperature and pressure are raised beyond the critical point. A key aspect of SCWR water chemistry control will be mitigation of the effects of water radiolysis; preliminary studies suggest markedly different behavior than that predicted from simple extrapolations from conventional water-cooled reactor behavior. The commonly used strategy of adding excess hydrogen at concentrations sufficient to suppress the net radiolytic production of primary oxidizing species may not be effective in an SCWR. The behavior of low concentrations of impurities such as transition metal corrosion products, chemistry control agents, anions introduced via make-up water or from ion-exchange resins, and radionuclides (e.g., 60 Co) needs to be understood. The formation of neutral complexes increases with temperature, and can become important under near-critical and supercritical conditions; the most important region is from 300-450 C, where the properties of water change dramatically, and solvent compressibility effects exert a huge influence on solvation. The potential for increased transport and deposition of corrosion products (active and inactive), leading to (a) increased deposition on fuel cladding surfaces, and (b) increased out-of-core radiation fields and worker dose, must be assessed. There are also significant challenges associated with chemistry sampling and monitoring in an SCWR. The typical methods used in current reactor designs (grab samples, on-line monitors at the end of a cooled, depressurized sample line) will be inadequate, and in-situ measurements of key parameters will be required. This paper describes current Canadian activities in SCWR chemistry and chemistry

  16. Gallstone fragmentation by control electrohydraulic lithotripsy

    International Nuclear Information System (INIS)

    Tung, G.A.; Mueller, P.R.; Brink, J.A.; Saini, S.; Picus, D.; Simeone, J.F.; Ferrucci, J.T.

    1989-01-01

    The authors have performed in vitro contact electrohydraulic lithotripsy (EHL) of 100 gallstones > 10 mm in diameter to identify physical and technical factors that affect fragmentation success. Ninety-one of 100 stones were fragmented with a 3-F electrode (average, seven shocks; range, 1--42); only 12 stones were fragmented with a single shock. Of the nine stones refractory to 50 shocks, four were > 30 mm in diameter and five stones were densely calcified. The most important variable determining power requirements for fragmentation was gallstone size (R = .58), but radiographic calcification of gallstones was also important (R = .47). Stones < 15 mm tended to produce fragments of left-angle 2 mm; stones right-angle 20 mm tended to produce two to five large discrete fragments (P , .05). In addition, lithotripsy could be conducted equally well in 1:1 dilute diatrizoate contrast agent as in 1:6 normal saline, suggesting that contact EHL could be performed under fluoroscopy

  17. Transforming fragments into candidates: small becomes big in medicinal chemistry.

    Science.gov (United States)

    de Kloe, Gerdien E; Bailey, David; Leurs, Rob; de Esch, Iwan J P

    2009-07-01

    Fragment-based drug discovery (FBDD) represents a logical and efficient approach to lead discovery and optimisation. It can draw on structural, biophysical and biochemical data, incorporating a wide range of inputs, from precise mode-of-binding information on specific fragments to wider ranging pharmacophoric screening surveys using traditional HTS approaches. It is truly an enabling technology for the imaginative medicinal chemist. In this review, we analyse a representative set of 23 published FBDD studies that describe how low molecular weight fragments are being identified and efficiently transformed into higher molecular weight drug candidates. FBDD is now becoming warmly endorsed by industry as well as academia and the focus on small interacting molecules is making a big scientific impact.

  18. Water chemistry: cause and control of corrosion degradation in nuclear power plants

    International Nuclear Information System (INIS)

    Kain, Vivekanand

    2008-01-01

    The corrosion degradation of a material is directly determined by the water chemistry, material (composition, fabrication procedure and microstructure) and by the stress/strain in the material under operating conditions. Water chemistry plays an important role in both uniform corrosion and localized forms of corrosion of materials. Once we understand how water chemistry is contributing to corrosion of a material, it is logical to modify/change that water chemistry to control the corrosion degradation. In nuclear power plants, different water chemistries have been used in different components/systems. This paper will cover the origin of corrosion degradation in the Primary Heat Transport system of different reactor types, Steam Generator tubing, secondary circuit pipelines, service water pipelines and auxiliary systems and establish the role of water chemistry in causing corrosion degradation. The history of changes in water chemistry adopted in these systems to control corrosion degradation is also described. It is shown by examples that there is an obvious limitation in changing water chemistry to control corrosion degradation and in those cases, a change of material or change of the state of stresses/fabrication procedure becomes necessary. The role of water chemistry as a causative factor and also as a controlling parameter on particular types of corrosion degradation e.g. stress corrosion cracking, flow accelerated corrosion, pitting, crevice corrosion is illustrated. It will be shown that increase in dissolved oxygen content (due to radiolysis in nuclear reactors) is sufficient to make even the de-mineralized water to cause stress corrosion cracking in Boiling Water Reactors. Hydrogen Water Chemistry (by hydrogen injection) to control dissolved oxygen is shown to control the stress corrosion cracking. However, it is not possible to control dissolved oxygen at all parts of the Boiling Water Reactors. Therefore, a further refinement in terms of noble metal

  19. BWR chemistry control status: a summary of industry chemistry status relative to the BWR water chemistry guidelines

    International Nuclear Information System (INIS)

    Garcia, S.E.; Giannelli, J.F.; Jarvis, M.L.

    2010-01-01

    The EPRI Boiling Water Reactor (BWR) Water Chemistry Guidelines were revised and issued in October 2008. The 2008 Revision of the Guidelines continues to focus on intergranular stress corrosion cracking (IGSCC), which can limit the service life of susceptible materials and components exposed to water chemistry environments. The 2008 Revision also places increased emphasis on fuel performance and meeting the industry goal of zero fuel failures by 2010. As an industry consensus document, the Guidelines were created to provide proactive water chemistry control strategies for mitigating IGSCC, maintaining fuel integrity and controlling radiation fields. The Guidelines provide a technically-based framework for an effective BWR water chemistry program. This paper provides an overview of industry experience relative to the Guidelines. Over the past few years, many BWR units have implemented noble metal chemical application technologies either during plant hot or cold shutdown or at normal power operating conditions. This paper explores plant experience with optimized water chemistry, implementation of various additive chemistries such as noble metal application and zinc addition, and compliance with the Guidelines recommendations. Depleted zinc oxide addition has been broadly applied across the BWR fleet since the 1980s. The guidance for zinc addition has been revised in the Guidelines to reflect concerns with fuel performance. While zinc addition is a successful method for shutdown dose rate control, concerns still exist for high zinc deposition on fuel surfaces, especially when feedwater iron is elevated and as fuel cores are being driven to provide maximum power output over longer fuel cycles. Recent plant experience has shown that the utilization of online noble metal application and continued zinc addition may provide additional benefits for radiation control. Dose rate experiences at plants utilizing the online noble metal application technology and zinc addition

  20. BWR chemistry control status: a summary of industry chemistry status relative to the BWR water chemistry guidelines

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, S.E., E-mail: sgarcia@epri.com [Electric Power Research Inst. (EPRI), Palo Alto, California (United States); Giannelli, J.F.; Jarvis, M.L., E-mail: jgiannelli@finetech.com [Finetech, Inc., Parsippany, NJ (United States)

    2010-07-01

    The EPRI Boiling Water Reactor (BWR) Water Chemistry Guidelines were revised and issued in October 2008. The 2008 Revision of the Guidelines continues to focus on intergranular stress corrosion cracking (IGSCC), which can limit the service life of susceptible materials and components exposed to water chemistry environments. The 2008 Revision also places increased emphasis on fuel performance and meeting the industry goal of zero fuel failures by 2010. As an industry consensus document, the Guidelines were created to provide proactive water chemistry control strategies for mitigating IGSCC, maintaining fuel integrity and controlling radiation fields. The Guidelines provide a technically-based framework for an effective BWR water chemistry program. This paper provides an overview of industry experience relative to the Guidelines. Over the past few years, many BWR units have implemented noble metal chemical application technologies either during plant hot or cold shutdown or at normal power operating conditions. This paper explores plant experience with optimized water chemistry, implementation of various additive chemistries such as noble metal application and zinc addition, and compliance with the Guidelines recommendations. Depleted zinc oxide addition has been broadly applied across the BWR fleet since the 1980s. The guidance for zinc addition has been revised in the Guidelines to reflect concerns with fuel performance. While zinc addition is a successful method for shutdown dose rate control, concerns still exist for high zinc deposition on fuel surfaces, especially when feedwater iron is elevated and as fuel cores are being driven to provide maximum power output over longer fuel cycles. Recent plant experience has shown that the utilization of online noble metal application and continued zinc addition may provide additional benefits for radiation control. Dose rate experiences at plants utilizing the online noble metal application technology and zinc addition

  1. Fragment growing exploiting dynamic combinatorial chemistry of inhibitors of the aspartic protease endothiapepsin

    NARCIS (Netherlands)

    Mondal, Milon; Groothuis, Daphne E.; Hirsch, Anna K. H.

    2015-01-01

    Fragment-based drug design (FBDD) has emerged as an efficient hit-identification and/or-optimization strategy with a higher hit rate than high-throughput screening (HTS). Whereas fragment linking is more challenging, fragment growing has become the preferred fragment-optimization strategy, requiring

  2. Fragment informatics and computational fragment-based drug design: an overview and update.

    Science.gov (United States)

    Sheng, Chunquan; Zhang, Wannian

    2013-05-01

    Fragment-based drug design (FBDD) is a promising approach for the discovery and optimization of lead compounds. Despite its successes, FBDD also faces some internal limitations and challenges. FBDD requires a high quality of target protein and good solubility of fragments. Biophysical techniques for fragment screening necessitate expensive detection equipment and the strategies for evolving fragment hits to leads remain to be improved. Regardless, FBDD is necessary for investigating larger chemical space and can be applied to challenging biological targets. In this scenario, cheminformatics and computational chemistry can be used as alternative approaches that can significantly improve the efficiency and success rate of lead discovery and optimization. Cheminformatics and computational tools assist FBDD in a very flexible manner. Computational FBDD can be used independently or in parallel with experimental FBDD for efficiently generating and optimizing leads. Computational FBDD can also be integrated into each step of experimental FBDD and help to play a synergistic role by maximizing its performance. This review will provide critical analysis of the complementarity between computational and experimental FBDD and highlight recent advances in new algorithms and successful examples of their applications. In particular, fragment-based cheminformatics tools, high-throughput fragment docking, and fragment-based de novo drug design will provide the focus of this review. We will also discuss the advantages and limitations of different methods and the trends in new developments that should inspire future research. © 2012 Wiley Periodicals, Inc.

  3. Cernavoda NPP - Boiler and steam cycle chemistry control

    International Nuclear Information System (INIS)

    Zotica, D.

    2001-01-01

    Steam generators protection against corrosion and fouling is an ongoing issue for nuclear power plants. The true effectiveness of the secondary chemistry control program is best judged by the absence of secondary side corrosion related tube degradation particularly that leads to tube plugging or sleeving or tube support degradation. To continue striving for excellence in chemical control, the following issues should be considered: Continuous evaluation of the effectiveness of the chemistry control program in mitigating SG damage; Evaluation of plant compliance with the program; Laboratory quality assurance program to assure that laboratory analyses are accurate and reproductibile; Quality assurance program for on-line monitoring equipment to assure that results from this equipment are accurate. (R.P.)

  4. Controlled isotropic fission fragment sources on the base of nuclear-physical facilities

    International Nuclear Information System (INIS)

    Sevast'yanov, V.D.; Maslov, G.N.

    1995-01-01

    Isotropic fission fragment sources (IFFS) are developed on the base of a neutron generator and pulse fast reactor. IFFS permit to calibrate fission fragment detectors. The IFFS consist of radiators with 235 U. The radiators are placed in a thermal neutron field of the neutron generator or in the reactor core center. The fragment activity is controlled by indications of an α-particle counter or by indications of a monitor of energy release in the core. 14 refs.; 1 fig.; 1 tab

  5. Developing a crevice chemistry control target from uncertain data

    International Nuclear Information System (INIS)

    Millett, P.J.

    1996-01-01

    It has been generally accepted that the corrosion of steam generator tubing could be reduced if the local pH in regions where impurities concentrate could be controlled. The practice of molar ratio control is based on this assumption. Direct measurement of the crevice chemistry is not possible at this time. Deterministic models based on bulk water conditions are quite uncertain, due to both the variability of crevices in the steam generator and the level of impurities in the bulk water which are often below or at the level of detection. The current methodology for assessing the crevice chemistry is to monitor the hideout return chemistry when the plant shuts down. This approach also has its shortcomings, but may provide sufficient data to evaluate whether the crevice pH is in a desirable range. In this paper, an approach for establishing a target crevice chemistry based on the plant data which is believed to be the most certain or reliable is presented

  6. Computational medicinal chemistry in fragment-based drug discovery: what, how and when.

    Science.gov (United States)

    Rabal, Obdulia; Urbano-Cuadrado, Manuel; Oyarzabal, Julen

    2011-01-01

    The use of fragment-based drug discovery (FBDD) has increased in the last decade due to the encouraging results obtained to date. In this scenario, computational approaches, together with experimental information, play an important role to guide and speed up the process. By default, FBDD is generally considered as a constructive approach. However, such additive behavior is not always present, therefore, simple fragment maturation will not always deliver the expected results. In this review, computational approaches utilized in FBDD are reported together with real case studies, where applicability domains are exemplified, in order to analyze them, and then, maximize their performance and reliability. Thus, a proper use of these computational tools can minimize misleading conclusions, keeping the credit on FBDD strategy, as well as achieve higher impact in the drug-discovery process. FBDD goes one step beyond a simple constructive approach. A broad set of computational tools: docking, R group quantitative structure-activity relationship, fragmentation tools, fragments management tools, patents analysis and fragment-hopping, for example, can be utilized in FBDD, providing a clear positive impact if they are utilized in the proper scenario - what, how and when. An initial assessment of additive/non-additive behavior is a critical point to define the most convenient approach for fragments elaboration.

  7. Water chemistry control practices and data of the European BWR fleet

    International Nuclear Information System (INIS)

    Stellwag, B.; Laendner, A.; Weiss, S.; Huettner, F.

    2010-01-01

    Nineteen BWR plants are in operation in Europe, nine built by ASEA Atom, six by Siemens KWU and four by General Electric. This paper gives an overview of water chemistry operation practices and parameters of the European BWR plants. General design characteristics of the plants are described. Chemistry control strategies and underlying water chemistry guidelines are summarized. Chemistry data are presented and discussed with regard to plant design characteristics. The paper is based on a contract of the European BWR Forum with AREVA on a chemistry sourcebook for member plants. The survey of chemistry data was conducted for the years 2002 to 2008. (author)

  8. Graph Theory. 1. Fragmentation of Structural Graphs

    Directory of Open Access Journals (Sweden)

    Lorentz JÄNTSCHI

    2002-12-01

    Full Text Available The investigation of structural graphs has many fields of applications in engineering, especially in applied sciences like as applied chemistry and physics, computer sciences and automation, electronics and telecommunication. The main subject of the paper is to express fragmentation criteria in graph using a new method of investigation: terminal paths. Using terminal paths are defined most of the fragmentation criteria that are in use in molecular topology, but the fields of applications are more generally than that, as I mentioned before. Graphical examples of fragmentation are given for every fragmentation criteria. Note that all fragmentation is made with a computer program that implements a routine for every criterion.[1] A web routine for tracing all terminal paths in graph can be found at the address: http://vl.academicdirect.ro/molecular_topology/tpaths/ [1] M. V. Diudea, I. Gutman, L. Jäntschi, Molecular Topology, Nova Science, Commack, New York, 2001, 2002.

  9. Controlling Chemistry in Dynamic Nanoscale Systems

    DEFF Research Database (Denmark)

    Jesorka, Aldo; Lizana, Ludvig; Konkoli, Zoran

    2011-01-01

    Spatial organization and shape dynamics are inherent properties of biological cells and cell interiors. There are strong indications that these features are important for the in vivo control of reaction parameters in biochemical transformations. Nanofluidic model devices founded on surfactant...... of the concept. Controlled release of chol-DNA molecules from SU-8 surfaces gives the possibility to dynamically change surface and/or solution properties in micro and nanoreactor applications, opening access to stable 2D chemistry on surface-based devices with potential for easy interfacing with conventional...

  10. Laser-assisted shape selective fragmentation of nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kazakevich, P.V. [Wave Research Center, General Physics Institute of the Russian Academy of Sciences, 38, Vavilov street, 117942 Moscow (Russian Federation); Simakin, A.V. [Wave Research Center, General Physics Institute of the Russian Academy of Sciences, 38, Vavilov street, 117942 Moscow (Russian Federation); Shafeev, G.A. [Wave Research Center, General Physics Institute of the Russian Academy of Sciences, 38, Vavilov street, 117942 Moscow (Russian Federation)]. E-mail: shafeev@kapella.gpi.ru; Viau, G. [ITODYS, UMR 7086, Universite Paris 7-Denis Diderot, case 7090, 2 place Jussieu, 75251 Paris Cedex 05 (France); Soumare, Y. [ITODYS, UMR 7086, Universite Paris 7-Denis Diderot, case 7090, 2 place Jussieu, 75251 Paris Cedex 05 (France); Bozon-Verduraz, F. [ITODYS, UMR 7086, Universite Paris 7-Denis Diderot, case 7090, 2 place Jussieu, 75251 Paris Cedex 05 (France)

    2007-07-31

    Experimental results are presented on laser-assisted fragmentation of gold-containing nanoparticles suspended in liquids (either ethanol or water). Two kinds of nanoparticles are considered: (i) elongated Au nanorods synthesized by laser ablation of a gold target immersed in liquid phase; (ii) gold-covered NiCo nanorods with high aspect ratio ({theta} {approx} 10) synthesized by wet chemistry processes. The shape selectivity induced by laser fragmentation of these nanorods is gained via tuning the wavelength of laser radiation into different parts of the spectrum of their plasmon resonance corresponding to different aspect ratios {theta}. Fragmentation is performed using three laser wavelengths, involving a Cu vapour laser (510 and 578 nm) and a Nd:YAG (1064 nm). Nanoparticles are characterized by UV-vis spectrometry, Transmission Electron Microscopy (TEM). The effect of laser pulse duration (nanosecond against picosecond range) is also studied in the case of fragmentation with an IR laser radiation.

  11. Size-controllable synthesis of bare gold nanoparticles by femtosecond laser fragmentation in water

    International Nuclear Information System (INIS)

    Maximova, Ksenia; Aristov, Andrei; Sentis, Marc; Kabashin, Andrei V

    2015-01-01

    We report a size-controllable synthesis of stable aqueous solutions of ultrapure low-size-dispersed Au nanoparticles by methods of femtosecond laser fragmentation from preliminary formed colloids. Such approach makes possible the tuning of mean nanoparticle size between a few nm and several tens of nm under the size dispersion lower than 70% by varying the fluence of pumping radiation during the fragmentation procedure. The efficient size control is explained by 3D geometry of laser fragmentation by femtosecond laser-induced white light super-continuum and plasma-related phenomena. Despite the absence of any protective ligands, the nanoparticle solutions demonstrate exceptional stability due to electric repulsion effect associated with strong negative charging of formed nanoparticles. Stable aqueous solutions of bare gold nanoparticles present a unique object with a variety of potential applications in catalysis, surface-enhanced Raman spectroscopy, photovoltaics, biosensing and biomedicine. (paper)

  12. Primary Water Chemistry Control during a Planned Outage at Bruce Power

    International Nuclear Information System (INIS)

    Ma, Guoping; Nashiem, Rod; Matheson, Shane; Yabar, Berman; Harper, Bill; Roberts, John G.

    2012-09-01

    Bruce Power has developed a comprehensive outage water chemistry program, which includes both primary and secondary chemistry requirements during planned outages. The purpose of the program is to emphasize the chemistry requirements during outages and subsequent start-ups in order to maintain the integrity of the systems, minimise activity transport and radiation fields, reduce the Carbon-14 release, and to ensure that the requirements are integrated with the outage management program. Prior to a planned outage, Station Chemical Technical Sections identify outage chemistry requirements to Operations and Outage Planning and ensure that work necessary to correct system chemistry issues is within outage work scope. The outage water chemistry program provides direction for establishing alternative sampling locations as demanded by the system configuration during the outage and identifies outage prerequisites for nuclear system purification capabilities. These requirements are contained in an outage checklist. The paper mainly highlights the primary water chemistry issues and chemistry control strategies during planned outages and discusses challenges and successes. (authors)

  13. Fragment-based drug discovery using rational design.

    Science.gov (United States)

    Jhoti, H

    2007-01-01

    Fragment-based drug discovery (FBDD) is established as an alternative approach to high-throughput screening for generating novel small molecule drug candidates. In FBDD, relatively small libraries of low molecular weight compounds (or fragments) are screened using sensitive biophysical techniques to detect their binding to the target protein. A lower absolute affinity of binding is expected from fragments, compared to much higher molecular weight hits detected by high-throughput screening, due to their reduced size and complexity. Through the use of iterative cycles of medicinal chemistry, ideally guided by three-dimensional structural data, it is often then relatively straightforward to optimize these weak binding fragment hits into potent and selective lead compounds. As with most other lead discovery methods there are two key components of FBDD; the detection technology and the compound library. In this review I outline the two main approaches used for detecting the binding of low affinity fragments and also some of the key principles that are used to generate a fragment library. In addition, I describe an example of how FBDD has led to the generation of a drug candidate that is now being tested in clinical trials for the treatment of cancer.

  14. Automated quantum chemistry based molecular dynamics simulations of electron ionization induced fragmentations of the nucleobases Uracil, Thymine, Cytosine, and Guanine.

    Science.gov (United States)

    Grimme, Stefan; Bauer, Christopher Alexander

    2015-01-01

    The gas-phase decomposition pathways of electron ionization (EI)-induced radical cations of the nucleobases uracil, thymine, cytosine, and guanine are investigated by means of mixed quantum-classical molecular dynamics. No preconceived fragmentation channels are used in the calculations. The results compare well to a plethora of experimental and theoretical data for these important biomolecules. With our combined stochastic and dynamic approach, one can access in an unbiased way the energetically available decomposition mechanisms. Additionally, we are able to separate the EI mass spectra of different tautomers of cytosine and guanine. Our method (previously termed quantum chemistry electron ionization mass spectra) reproduces free nucleobase experimental mass spectra well and provides detailed mechanistic in-sight into high-energy unimolecular decomposition processes.

  15. Identification of major sources controlling groundwater chemistry ...

    Indian Academy of Sciences (India)

    The study area Mettur forms an important industrial town situated NW of Salem district. The geology of the area is mainly composed of Archean crystalline metamorphic complexes. To iden- tify the major process activated for controlling the groundwater chemistry an attempt has been made by collecting a total of 46 ...

  16. “Gold” Pressed Essential Oil: An Essay on the Volatile Fragment from Citrus Juice Industry By-Products Chemistry and Bioactivity

    Directory of Open Access Journals (Sweden)

    V. N. Kapsaski-Kanelli

    2017-01-01

    Full Text Available Present essay explores the potentials of Citrus juice industry’s by-products as alternative bioactive natural products resources. Four crude Cold Pressed Essential Oils (CPEOs, derived from orange, lemon, grapefruit, and mandarin, were studied. All CPEOs were subjected to water distillation, in order to obtain the volatile fragment, which was further fractionated with respect to distillation period in two parts, concluding to eight samples. These samples along with the four original CPEOs were assessed in relation to their phytochemical content and their repellent and larvicidal properties against Asian Tiger Mosquito. The volatiles recovery rates ranged from 74% to 88% of the CPEO. Limonene presented a significant increase in all samples ranging from 8% to 52% of the respective CPEO’s content and peaked in mandarin’s 2nd volatile fragment which comprised 97% of the essential oil. The refinement process presented clear impacts on both bioassays: a significant increase in larvicidal potency was observed, annotated best by the improvement by 1100% and 1300% of the grapefruit volatile fractions; repellence testing provided only one significant result, the decrease of landings by 50% as a response to mandarin’s second volatile fraction. The applied methodology thus may be considered for the improvement of Citrus juice industry’s by-products chemistry and bioactivity.

  17. Radiation chemistry of aqueous solutions of acetonitrile and propionitrile

    International Nuclear Information System (INIS)

    Shushtarian, M.J.

    1975-01-01

    The radiation chemistry of water and aqueous solutions is a branch of radiation chemistry dealing with chemical changes in water and aqueous solutions induced by high energy radiations. High energy radiations of interest in radiation chemistry are short-wave electromagnetic radiations (X- and γ-rays) and fast charged particles (α- and β-particles, electrons, deuterons and fission fragments). The energy of the particles and photons bringing about chemical reactions in the field of modern radiation chemistry is much higher than that of photons causing photochemical reactions

  18. PWR primary system chemistry control during hot functional testing

    International Nuclear Information System (INIS)

    Reid, Richard D.; Little, Michael J.

    2014-01-01

    Hot Functional Testing (HFT) involves a number of pre-operational exercises performed to confirm the operability of plant systems at conditions expected during both normal and off-normal operation of a pressurized water reactor (PWR), including operability of safety systems. While the primary purposes of HFT are to demonstrate operability of plant systems and satisfy regulatory requirements, chemistry control during HFT is important to long-term integrity and performance of plant systems. Specifically, HFT is the first time plant equipment is exposed to high temperature water and the chemistry maintained during HFT can impact the passivation layers that form on wetted surfaces and long-term release of metals from these surfaces. Metals released from the inner surfaces of steam generator tubing and reactor coolant loop piping become activated in the core and can redeposit on ex-core surfaces. Because HFT is performed before fuel is loaded in the core, HFT provides an opportunity to produce a passive layer on primary surfaces that is free of activated corrosion products, resistant to metals release during subsequent plant operation, and also resistant to incorporation of activated corrosion products (once fuel is loaded in the core). Thus, maintaining desirable primary chemistry control during HFT is important for source term management, minimization of future shutdown activity releases, minimization of dose rates, and asset preservation. This paper presents an overview of passive film formation in the austenitic stainless steel and high nickel alloys that make up the majority of the primary circuit in advanced PWR designs. Based on this information, a summary is provided of the effects on passive film formation of key chemistry parameters that may be controlled during HFT. (author)

  19. When fragments link: a bibliometric perspective on the development of fragment-based drug discovery.

    Science.gov (United States)

    Romasanta, Angelo K S; van der Sijde, Peter; Hellsten, Iina; Hubbard, Roderick E; Keseru, Gyorgy M; van Muijlwijk-Koezen, Jacqueline; de Esch, Iwan J P

    2018-05-05

    Fragment-based drug discovery (FBDD) is a highly interdisciplinary field, rich in ideas integrated from pharmaceutical sciences, chemistry, biology, and physics, among others. To enrich our understanding of the development of the field, we used bibliometric techniques to analyze 3642 publications in FBDD, complementing accounts by key practitioners. Mapping its core papers, we found the transfer of knowledge from academia to industry. Co-authorship analysis showed that university-industry collaboration has grown over time. Moreover, we show how ideas from other scientific disciplines have been integrated into the FBDD paradigm. Keyword analysis showed that the field is organized into four interconnected practices: library design, fragment screening, computational methods, and optimization. This study highlights the importance of interactions among various individuals and institutions from diverse disciplines in newly emerging scientific fields. Copyright © 2018. Published by Elsevier Ltd.

  20. Chemistry, manufacturing and controls in passive transdermal drug delivery systems.

    Science.gov (United States)

    Goswami, Tarun; Audett, Jay

    2015-01-01

    Transdermal drug delivery systems (TDDS) are used for the delivery of the drugs through the skin into the systemic circulation by applying them to the intact skin. The development of TDDS is a complex and multidisciplinary affair which involves identification of suitable drug, excipients and various other components. There have been numerous problems reported with respect to TDDS quality and performance. These problems can be reduced by appropriately addressing chemistry, manufacturing and controls requirements, which would thereby result in development of robust TDDS product and processes. This article provides recommendations on the chemistry, manufacturing and controls focusing on the unique technical aspects of TDDS.

  1. Fragment-based approaches to the discovery of kinase inhibitors.

    Science.gov (United States)

    Mortenson, Paul N; Berdini, Valerio; O'Reilly, Marc

    2014-01-01

    Protein kinases are one of the most important families of drug targets, and aberrant kinase activity has been linked to a large number of disease areas. Although eminently targetable using small molecules, kinases present a number of challenges as drug targets, not least obtaining selectivity across such a large and relatively closely related target family. Fragment-based drug discovery involves screening simple, low-molecular weight compounds to generate initial hits against a target. These hits are then optimized to more potent compounds via medicinal chemistry, usually facilitated by structural biology. Here, we will present a number of recent examples of fragment-based approaches to the discovery of kinase inhibitors, detailing the construction of fragment-screening libraries, the identification and validation of fragment hits, and their optimization into potent and selective lead compounds. The advantages of fragment-based methodologies will be discussed, along with some of the challenges associated with using this route. Finally, we will present a number of key lessons derived both from our own experience running fragment screens against kinases and from a large number of published studies.

  2. Effective progression of nuclear magnetic resonance-detected fragment hits.

    Science.gov (United States)

    Eaton, Hugh L; Wyss, Daniel F

    2011-01-01

    Fragment-based drug discovery (FBDD) has become increasingly popular over the last decade as an alternate lead generation tool to HTS approaches. Several compounds have now progressed into the clinic which originated from a fragment-based approach, demonstrating the utility of this emerging field. While fragment hit identification has become much more routine and may involve different screening approaches, the efficient progression of fragment hits into quality lead series may still present a major bottleneck for the broadly successful application of FBDD. In our laboratory, we have extensive experience in fragment-based NMR screening (SbN) and the subsequent iterative progression of fragment hits using structure-assisted chemistry. To maximize impact, we have applied this approach strategically to early- and high-priority targets, and those struggling for leads. Its application has yielded a clinical candidate for BACE1 and lead series in about one third of the SbN/FBDD projects. In this chapter, we will give an overview of our strategy and focus our discussion on NMR-based FBDD approaches. Copyright © 2011 Elsevier Inc. All rights reserved.

  3. PWR water chemistry controls: a perspective on industry initiatives and trends relative to operating experience and the EPRI PWR water chemistry guidelines

    International Nuclear Information System (INIS)

    Fruzzetti, K.; Choi, S.; Haas, C.; Pender, M.; Perkins, D.

    2010-01-01

    An effective PWR water chemistry control program must address the following goals: Minimize materials degradation (e.g., PWSCC, corrosion of fuel, corrosion damage of steam generator (SG) tubes); Maintain fuel integrity and good performance; Minimize corrosion product transport (e.g., transport and deposition on the fuel, transport into the SGs where it can foul tube surfaces and create crevice environments for the concentration of corrosive impurities); Minimize dose rates. Water chemistry control must be optimized to provide overall improvement considering the sometimes variant constraints of the goals listed above. New technologies are developed for continued mitigation of materials degradation, continued fuel integrity and good performance, continued reduction of corrosion product transport, and continued minimization of plant dose rates. The EPRI chemistry program, in coordination with other EPRI programs, strives to improve these areas through application of chemistry initiatives, focusing on these goals. This paper highlights the major initiatives and issues with respect to PWR primary and secondary system chemistry and outlines the recent, on-going, and proposed work to effectively address them. These initiatives are presented in light of recent operating experience, as derived from EPRI's PWR chemistry monitoring and assessment program, and EPRI's water chemistry guidelines. (author)

  4. Medicinal chemistry inspired fragment-based drug discovery.

    Science.gov (United States)

    Lanter, James; Zhang, Xuqing; Sui, Zhihua

    2011-01-01

    Lead generation can be a very challenging phase of the drug discovery process. The two principal methods for this stage of research are blind screening and rational design. Among the rational or semirational design approaches, fragment-based drug discovery (FBDD) has emerged as a useful tool for the generation of lead structures. It is particularly powerful as a complement to high-throughput screening approaches when the latter failed to yield viable hits for further development. Engagement of medicinal chemists early in the process can accelerate the progression of FBDD efforts by incorporating drug-friendly properties in the earliest stages of the design process. Medium-chain acyl-CoA synthetase 2b and ketohexokinase are chosen as examples to illustrate the importance of close collaboration of medicinal chemists, crystallography, and modeling. Copyright © 2011 Elsevier Inc. All rights reserved.

  5. Water chemistry control to meet the advanced design and operation of light water reactors

    International Nuclear Information System (INIS)

    Shirai, Hiroshi; Uchida, Shunsuke; Naitoh, Masanori; Okada, Hidetoshi; Sato, Masatoshi

    2014-01-01

    Water chemistry control is one of the key technologies to establish safe and reliable operation of nuclear power plants. The road maps on R and D plans for water chemistry of nuclear power systems in Japan have been proposed along with promotion of R and D related water chemistry improvement for the advanced application of light water reactors (LWRs). The technical trends were divided into four categories, dose rate reduction, structural integrity, fuel integrity and radioactive waste reduction, and latest technical break through for each category was shown for the advanced application of LWRs. At the same time, the technical break through and the latest movements for regulation of water chemistry were introduced for each of major organizations related to nuclear engineering in the world. The conclusions were summarized as follows; 1. Water chemistry improvements might contribute to achieve the advanced application of LWRs, while water chemistry should be often changed to achieve the advanced application of LWRs. 2. Only one solution for water chemistry control was not obtained for achieving the advanced application of LWRs, but miscellaneous solutions were possible for achieving one. Optimal water chemistry control was desired for having the good practices for satisfying multi-targets at the same time and it was much affected by the plant unique systems and operational history. 3. That meant it was difficult to determine water chemistry regulation targets for achieving application of LWRs but it was necessary to prepare suitable guideline for good achievement of application of LWRs. That meant the guideline should be recommendation for good practice in the plant. 4. The water chemistry guide line should be modified along with progress of plant operation and water chemistry and related technologies. (author)

  6. Water Chemistry Control in Reducing Corrosion and Radiation Exposure at PWR Reactor

    International Nuclear Information System (INIS)

    Febrianto

    2006-01-01

    Water chemistry control plays an important role in relation to plant availability, reliability and occupational radiation exposures. Radiation exposures of nuclear plant workers are determined by the radiation rate dose and by the amount maintenance and repair work time Water chemistry has always been, from beginning of operation of power Pressurized Water Reactor, an important factor in determining the integrity of reactor components, fuel cladding integrity and minimize out of core radiation exposures. For primary system, the parameters to control the quality of water chemistry have been subject to change in time. Reactor water coolant pH need to be optimally controlled and be operated in range pH 6.9 to 7.4. At pH lower than 6.9, cause increasing the radiation exposure level and increasing coolant water pH higher than 7.4 will decrease radiation exposure level but increasing risk to fuel cladding and steam generator tube. Since beginning 90 decade, PWR water coolant pH tend to be operated at pH 7.4. This paper will discuss concerning water chemistry development in reducing corrosion and radiation exposure dose in PWR reactor. (author)

  7. Electron impact fragmentation of size-selected krypton clusters

    Czech Academy of Sciences Publication Activity Database

    Steinbach, Ch.; Fárník, Michal; Buck, U.; Brindle, C. A.; Janda, K. C.

    2006-01-01

    Roč. 110, č. 29 (2006), s. 9108-9115 ISSN 1089-5639 Grant - others:Deutsche Forschungsgemeinschaft(DE) GRK 782; US National Science Foundation(US) CHE-0213149 Institutional research plan: CEZ:AV0Z40400503 Keywords : rare-gas cluster * bombardment fragmentation * scattering analysis Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.047, year: 2006

  8. BWR Water Chemistry Guidelines: 1993 Revision, Normal and hydrogen water chemistry

    International Nuclear Information System (INIS)

    Karlberg, G.; Goddard, C.; Fitzpatrick, S.

    1994-02-01

    The goal of water chemistry control is to extend the operating life of the reactor and rector coolant system, balance-of-plant components, and turbines while simultaneously controlling costs to safeguard the continued economic viability of the nuclear power generation investment. To further this goal an industry committee of chemistry personnel prepared guidelines to identify the benefits, risks, and costs associated with water chemistry in BWRs and to provide a template for an optimized water chemistry program. This document replaces the BWR Normal Water Chemistry Guidelines - 1986 Revision and the BWR Hydrogen Water Chemistry Guidelines -- 1987 Revision. It expands on the previous guidelines documents by covering the economic implications of BWR water chemistry control

  9. Aspects and prospects of the chemistry of organic heterocycles (review)

    International Nuclear Information System (INIS)

    Schroth, W.

    1986-01-01

    The systematics of heterocycles, their place in organic chemistry, and their significance for theory and practice are discussed. Problems of the chemistry of heterocycles are discussed on the examples of systems with various types of conjugation and ring sizes. The focus is on the principles of synthesis of heterocycles, in particular, those based on acetylene, various C 3 fragments, carbon disulfide, and maleic anhydride. Individual sections of the survey are devoted to the role of heterocycles in biosynthesis, as well as certain problems common to the chemistry of heterocycles, biochemistry, and macromolecular chemistry

  10. Racing performance of Swedish Standardbred trotting horses with proximal palmar/plantar first phalangeal (Birkeland) fragments compared to fragment free controls.

    Science.gov (United States)

    Carmalt, James L; Borg, Hanna; Näslund, Hans; Waldner, Cheryl

    2014-10-01

    The aim of this study was to determine whether horses with a proximal palmar/plantar first phalangeal osteochondral fragment (POF) had comparable racing careers (prior to and following surgery) to horses without this fracture. A retrospective cohort study included 174 Swedish Standardbred trotters with osteochondral fragmentation in the palmar/plantar fetlock joint and 613 radiographically negative control horses presented for prepurchase examinations. Medical records and radiographs were examined for each horse. Racing data were retrieved from online Swedish Standardbred harness racing records. The effect of having a POF on race speed compared to radiographically negative control horses was examined using generalised estimating equations. Multivariable regression was used to examine differences in money earned and career longevity. The horses raced a total of 16,448 races. Horses gained speed as a function of race number. There was no difference in racing speed between horses with POF fractures that raced before surgery and control horses. Horses did not slow before, nor speed up after, surgery. There was no difference in the number of days between the last race prior to, or the first race after, the hospital visit between POF and control horses. Career earnings and lifetime starts were not significantly different between groups. The results of this study suggest the need to reevaluate the previously reported benefits of surgical intervention for POF. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Characterization of Tumor-Avid Antibody Fragments Genetically Engineered for Mono-Specific Radionuclide Chelation

    International Nuclear Information System (INIS)

    Quinn, T.P.

    2003-01-01

    The successful clinical application of targeted-radiopharmaceuticals depends on the development of molecules that optimize tumor specific radionuclide deposition and minimize non-specific organ irradiation. To this end, this proposal outlines a research effort to identify and evaluate novel antibodies and antibody fragments that bind breast tumors. The tumor-avid antibodies will be investigated for as imaging and therapeutic agents and to gain a better understanding of the pharmacokinetics and metabolism of radiolabeled tumor-avid antibody fragments through the use of site-specifically labeled molecules. Antibodies or antibody fragments, that bind breast carcinoma carbohydrate antigens, will be obtained from hybridoma or bacteriophage library screening. More specifically, antibody fragments that bind the carcinoma-associated Thomsen-Friedenreich (T) antigen will be radiolabeled with 99m Tc and 188 Re at a natural amino acid chelation site and will be investigated in vivo for their abilities to target human breast tumors. In addition, site-specific radiolabeled antibody fragments will be biosynthesized using misacylated suppressor tRNAs. Homogeneously radiolabeled populations of antibody fragments will be used to investigate the effects of radionuclide location and chelation chemistries on their biodistribution and metabolism. It is hypothesized that site-specifically radiolabeled antibody fragments will possess enhanced tumor imaging and therapeutic properties due to optimal label location and conjugation chemistries. New insights into the factors that govern antibody metabolism in vivo are also expected from this work. Results from these studies should enhance our ability to design and synthesize radiolabeled antibody fragments that have improved pharmacokinetic properties. The studies in this proposal involve basic research into the development of antibody-based radiopharmaceuticals, with the ultimate goal of application in humans. This type of basic nuclear

  12. Design Principles for Fragment Libraries: Maximizing the Value of Learnings from Pharma Fragment-Based Drug Discovery (FBDD) Programs for Use in Academia.

    Science.gov (United States)

    Keserű, György M; Erlanson, Daniel A; Ferenczy, György G; Hann, Michael M; Murray, Christopher W; Pickett, Stephen D

    2016-09-22

    Fragment-based drug discovery (FBDD) is well suited for discovering both drug leads and chemical probes of protein function; it can cover broad swaths of chemical space and allows the use of creative chemistry. FBDD is widely implemented for lead discovery in industry but is sometimes used less systematically in academia. Design principles and implementation approaches for fragment libraries are continually evolving, and the lack of up-to-date guidance may prevent more effective application of FBDD in academia. This Perspective explores many of the theoretical, practical, and strategic considerations that occur within FBDD programs, including the optimal size, complexity, physicochemical profile, and shape profile of fragments in FBDD libraries, as well as compound storage, evaluation, and screening technologies. This compilation of industry experience in FBDD will hopefully be useful for those pursuing FBDD in academia.

  13. Best possible cycle chemistry control in steam turbine plants; Baesta moejliga oevervakning av vattenkemin i anlaeggningar med aangturbin

    Energy Technology Data Exchange (ETDEWEB)

    Hellman, Mats [Hellman Vatten AB, Stockholm (Sweden)

    2004-11-01

    A project has been conducted of a large number of power and pulp plants in Sweden. Production managers and those responsible for water quality control were visited and interviewed. In addition, a research of cycle chemistry literature has been conducted to determine what has been done in other countries. The review of this literature shows that the Electric Power Research Institute in the USA and ESKOM in South Africa are in the forefront regarding QA/QC and have come a long way in water control management. A key requirement for successful plant cycle chemistry is corporate management support. The project makes it clear that cycle chemistry control was best at plants where production management was aware of the importance of high water quality. There is a real need for feed water technique and water quality education at all company levels. The objective should be that 'everyone should know the importance of right water quality'. Personnel without an education in chemistry often regard cycle chemistry as somewhat complicated. Better understanding and better working cycle chemistry control can be obtained by making the control easier and clearer for persons without training in chemistry. Extensive on-line instrumentation with well-designed systems for presenting the data, by-far, gives the best cycle chemistry control. It is important to have a holistic view when water treatment systems and on-line instrumentation are planned. It is not the amount of instruments or the number of chemistry personnel that is important. The important thing is to ensure that all functions needed fit together in the best way possible. Today, when cycle chemistry monitoring is heavily dependent on on-line instrumentation, the reliability of the instruments is crucial. Therefore, it is important to have well-established routines for maintenance, calibration and service. In order to decrease forced outages of plants due to poor cycle chemistry, the focus of chemistry control should

  14. Chemistry with spatial control using particles and streams†

    Science.gov (United States)

    Kalinin, Yevgeniy V.; Murali, Adithya

    2012-01-01

    Spatial control of chemical reactions, with micro- and nanometer scale resolution, has important consequences for one pot synthesis, engineering complex reactions, developmental biology, cellular biochemistry and emergent behavior. We review synthetic methods to engineer this spatial control using chemical diffusion from spherical particles, shells and polyhedra. We discuss systems that enable both isotropic and anisotropic chemical release from isolated and arrayed particles to create inhomogeneous and spatially patterned chemical fields. In addition to such finite chemical sources, we also discuss spatial control enabled with laminar flow in 2D and 3D microfluidic networks. Throughout the paper, we highlight applications of spatially controlled chemistry in chemical kinetics, reaction-diffusion systems, chemotaxis and morphogenesis. PMID:23145348

  15. Residue preference mapping of ligand fragments in the Protein Data Bank.

    Science.gov (United States)

    Wang, Lirong; Xie, Zhaojun; Wipf, Peter; Xie, Xiang-Qun

    2011-04-25

    The interaction between small molecules and proteins is one of the major concerns for structure-based drug design because the principles of protein-ligand interactions and molecular recognition are not thoroughly understood. Fortunately, the analysis of protein-ligand complexes in the Protein Data Bank (PDB) enables unprecedented possibilities for new insights. Herein, we applied molecule-fragmentation algorithms to split the ligands extracted from PDB crystal structures into small fragments. Subsequently, we have developed a ligand fragment and residue preference mapping (LigFrag-RPM) algorithm to map the profiles of the interactions between these fragments and the 20 proteinogenic amino acid residues. A total of 4032 fragments were generated from 71 798 PDB ligands by a ring cleavage (RC) algorithm. Among these ligand fragments, 315 unique fragments were characterized with the corresponding fragment-residue interaction profiles by counting residues close to these fragments. The interaction profiles revealed that these fragments have specific preferences for certain types of residues. The applications of these interaction profiles were also explored and evaluated in case studies, showing great potential for the study of protein-ligand interactions and drug design. Our studies demonstrated that the fragment-residue interaction profiles generated from the PDB ligand fragments can be used to detect whether these fragments are in their favorable or unfavorable environments. The algorithm for a ligand fragment and residue preference mapping (LigFrag-RPM) developed here also has the potential to guide lead chemistry modifications as well as binding residues predictions.

  16. South African Journal of Chemistry - Vol 56 (2003)

    African Journals Online (AJOL)

    South African Journal of Chemistry. ... Synthesis and antimicrobial activity of new Thiazole-2(3H)-thiones containing 1, 1, 3-trisubstituted Cyclobutane · EMAIL ... Part 12.1 Fragmentation Patterns in the Electron-impact Mass Spectra of 2-(N, ...

  17. A prototype expert system 'SMART' for water chemistry control in reactor water circuits

    International Nuclear Information System (INIS)

    Rangarajan, S.; Narasimhan, S.V.

    1998-01-01

    The operational safety of a power plant depends mainly on the material compatibility of the system materials with the environment. However, for an operating plant, the material is almost fixed and hence one can improve the safety by controlling the surrounding environment. From the economy point of view, the plant availability factor as well as plant life extension (PLEX) are important considerations and these necessitate a systematic approach for continuous parametric monitoring, rapid data analysis and diagnosis for controlling the water chemistry regime. A prototype expert system 'SMART' was developed in BASIC language. The expert system consists of four modules. The DATA HANDLER module controls all the data handling functions and graphical display of the data parameters. It also generates weekly and monthly reports of the water chemistry data. The DATA INTERPRETER module compares the experimental data with the theoretically calculated values and predicts the presence of impurity ingress in the system. The CHEMISTRY EXPERT contains the knowledge base about the various sub-systems. All the water chemistry specifications are translated in the form of IF... THEN.. rules and are stored in this module. The expert system inferences with the forward chain reasoning mechanism to identify the diagnostic parameters by consulting the knowledge base and applying the appropriate rules. The ACTION EXPERT module collects all the diagnostic parameters and suggests the operator, the remedial actions/counter measures that should be taken immediately. This rule based system can be expanded to accommodate different water chemistry regimes. (author)

  18. Spatially controlled immobilisation of biomolecules: A complete approach in green chemistry

    Science.gov (United States)

    Grinenval, Eva; Nonglaton, Guillaume; Vinet, Françoise

    2014-01-01

    The development of 'green' sensors is a challenging task in the field of biomolecule sensing, for example in the detection of cardiac troponin-I (cTnI). In the present work a complete approach in green chemistry was developed to create chemically active patterns for the immobilisation of biological probes. This key technology is discussed on the basis of the twelve green chemistry principles, and is a combination of surface patterning by spotting and surface chemistries modified by molecular vapour deposition. The (1H,1H,2H,2H)-perfluorodecyltrichlorosilane (FDTS) was used as a novel anti-adsorption layer while the 3,4-epoxybutyltrimethoxysilane (EBTMOS) was used to immobilise probes. Oligonucleotides and the anti-cTnI antibody were studied. The spatially controlled immobilisation of probes was characterised by fluorescence. The demonstrated surface modification has broad applications in areas such as diagnostics and bio-chemical sensing. Moreover, the environmental impacts of surface patterning and surface chemistry were discussed from a 'greenness' point of view.

  19. Intuitive Judgments Govern Students' Answering Patterns in Multiple-Choice Exercises in Organic Chemistry

    Science.gov (United States)

    Graulich, Nicole

    2015-01-01

    Research in chemistry education has revealed that students going through their undergraduate and graduate studies in organic chemistry have a fragmented conceptual knowledge of the subject. Rote memorization, rule-based reasoning, and heuristic strategies seem to strongly influence students' performances. There appears to be a gap between what we…

  20. The rise of fragment-based drug discovery.

    Science.gov (United States)

    Murray, Christopher W; Rees, David C

    2009-06-01

    The search for new drugs is plagued by high attrition rates at all stages in research and development. Chemists have an opportunity to tackle this problem because attrition can be traced back, in part, to the quality of the chemical leads. Fragment-based drug discovery (FBDD) is a new approach, increasingly used in the pharmaceutical industry, for reducing attrition and providing leads for previously intractable biological targets. FBDD identifies low-molecular-weight ligands (∼150 Da) that bind to biologically important macromolecules. The three-dimensional experimental binding mode of these fragments is determined using X-ray crystallography or NMR spectroscopy, and is used to facilitate their optimization into potent molecules with drug-like properties. Compared with high-throughput-screening, the fragment approach requires fewer compounds to be screened, and, despite the lower initial potency of the screening hits, offers more efficient and fruitful optimization campaigns. Here, we review the rise of FBDD, including its application to discovering clinical candidates against targets for which other chemistry approaches have struggled.

  1. Antiparallel Dynamic Covalent Chemistries.

    Science.gov (United States)

    Matysiak, Bartosz M; Nowak, Piotr; Cvrtila, Ivica; Pappas, Charalampos G; Liu, Bin; Komáromy, Dávid; Otto, Sijbren

    2017-05-17

    The ability to design reaction networks with high, but addressable complexity is a necessary prerequisite to make advanced functional chemical systems. Dynamic combinatorial chemistry has proven to be a useful tool in achieving complexity, however with some limitations in controlling it. Herein we introduce the concept of antiparallel chemistries, in which the same functional group can be channeled into one of two reversible chemistries depending on a controllable parameter. Such systems allow both for achieving complexity, by combinatorial chemistry, and addressing it, by switching from one chemistry to another by controlling an external parameter. In our design the two antiparallel chemistries are thiol-disulfide exchange and thio-Michael addition, sharing the thiol as the common building block. By means of oxidation and reduction the system can be reversibly switched from predominantly thio-Michael chemistry to predominantly disulfide chemistry, as well as to any intermediate state. Both chemistries operate in water, at room temperature, and at mildly basic pH, which makes them a suitable platform for further development of systems chemistry.

  2. Chemistry control approach of pre commissioning and power operation of primary and auxiliary system of KGS-3 and 4 and trouble shooting made

    International Nuclear Information System (INIS)

    Bennet Raj, N.; Sahu, B.S.; Kumar, Vineet; Valluri, J.

    2008-01-01

    KGS (Kaiga Generating Station) 3 and 4 is a 220 MWe pressurized heavy water reactor (PHWR) using heavy water (D 2 O) as moderator and primary heat coolant and the secondary system is light water which is used to make the steam for generating the power. The chemistry control approach made for the successful commissioning and subsequent power operation of the unit is discussed here. The chemistry control is of two parts first part covers the pre commissioning chemistry control and the second part covers the commissioning chemistry control. During commissioning all systems were preserved by proper chemistry control and regular recirculation of system to avoid stagnancy. The major pre commissioning and commissioning chemistry control are depicted below: Pre commissioning chemistry control of primary heat transport (PHT) system and auxiliaries; Pre commissioning chemistry control of moderator system; Primary heat transport system hot conditioning with light water; Commissioning chemistry control of End Shield System (ESC) and Calandria Vault Cooling (CVC) system; Heavy water addition and its chemistry control in moderator system; and Heavy water addition and its chemistry control in PHT system. During power operation dew point in annular gas monitoring system (AGMS) of KGS unit 3 was maintaining in higher side under recirculation. The increase of dew point could be due to ingress of heavy water or light water. A new device was developed to collect condensate and the chemistry of the condensate was checked. The result indicated the ingress of light water. (author)

  3. Eutrophication and contaminant data management for EU marine policies: the EMODnet Chemistry infrastructure.

    Science.gov (United States)

    Vinci, Matteo; Lipizer, Marina; Giorgetti, Alessandra

    2016-04-01

    The European Marine Observation and Data Network (EMODnet) initiative has the following purposes: to assemble marine metadata, data and products, to make these fragmented resources more easily available to public and private users and to provide quality-assured, standardised and harmonised marine data. EMODnet Chemistry was launched by DG MARE in 2009 to support the Marine Strategy Framework Directive (MSFD) requirements for the assessment of eutrophication and contaminants, following INSPIRE Directive rules. The aim is twofold: the first task is to make available and reusable the big amount of fragmented and inaccessible data, hosted in the European research institutes and environmental agencies. The second objective is to develop visualization services useful for the tasks of the MSFD. The technical set-up is based on the principle of adopting and adapting the SeaDataNet infrastructure for ocean and marine data which are managed by National Oceanographic Data Centers and relies on a distributed network of data centers. Data centers contribute to data harvesting and enrichment with the relevant metadata. Data are processed into interoperable formats (using agreed standards ISO XML, ODV) with the use of common vocabularies and standardized quality control procedures .Data quality control is a key issue when merging heterogeneous data coming from different sources and a data validation loop has been agreed within EMODnet Chemistry community and is routinely performed. After data quality control done by the regional coordinators of the EU marine basins (Atlantic, Baltic, North, Mediterranean and Black Sea), validated regional datasets are used to develop data products useful for the requirements of the MSFD. EMODnet Chemistry provides interpolated seasonal maps of nutrients and services for the visualization of time series and profiles of several chemical parameters. All visualization services are developed following OGC standards as WMS and WPS. In order to test new

  4. Dual Fragment Impact of PBX Charges

    Science.gov (United States)

    Haskins, Peter; Briggs, Richard; Leeming, David; White, Nathan; Cheese, Philip; DE&S MoD UK Team; Ordnance Test Solutions Ltd Team

    2017-06-01

    Fragment impact can pose a significant hazard to many systems containing explosives or propellants. Testing for this threat is most commonly carried out using a single fragment. However, it can be argued that an initial fragment strike (or strikes) could sensitise the energetic material to subsequent impacts, which may then lead to a more violent reaction than would have been predicted based upon single fragment studies. To explore this potential hazard we have developed the capability to launch 2 fragments from the same gun at a range of velocities, and achieve impacts on an acceptor charge with good control over the spatial and temporal separation of the strikes. In this paper we will describe in detail the experimental techniques we have used, both to achieve the dual fragment launch and observe the acceptor charge response. In addition, we will describe the results obtained against PBX filled explosive targets; discuss the mechanisms controlling the target response and their significance for vulnerability assessment. Results of these tests have clearly indicated the potential for detonation upon the second strike, at velocities well below those needed for shock initiation by a single fragment.

  5. High temperature water chemistry monitoring

    International Nuclear Information System (INIS)

    Aaltonen, P.

    1992-01-01

    Almost all corrosion phenomena in nuclear power plants can be prevented or at least damped by water chemistry control or by the change of water chemistry control or by the change of water chemistry. Successful water chemistry control needs regular and continuous monitoring of such water chemistry parameters like dissolved oxygen content, pH, conductivity and impurity contents. Conventionally the monitoring is carried out at low pressures and temperatures, which method, however, has some shortcomings. Recently electrodes have been developed which enables the direct monitoring at operating pressures and temperatures. (author). 2 refs, 5 figs

  6. Validating the Use of Rectus Muscle Fragment Welding to Control Presacral Bleeding During Rectal Mobilization

    Directory of Open Access Journals (Sweden)

    Eduardo Ayuste, Jr.

    2004-01-01

    Full Text Available The incidence of presacral bleeding during rectal mobilization is low, but such bleeding may be massive and even fatal. Haemostasis can be difficult to achieve using conventional methods because of the complex interlacing of the venous network at the sacral periosteum. Historically, pelvic packing and metallic thumbtacks have been the more commonly used methods in our institution. However, the need for repeat surgery to remove the packs and the difficulties encountered in tack application have forced us to explore other methods. In 1994, the procedure termed muscle fragment welding, which uses electrocautery through a rectus muscle fragment, was introduced to control presacral bleeding. From January 1999 to February 2002, six of 416 patients undergoing pelvic surgery in our institution developed massive presacral haemorrhage and, therefore, this technique was used. Haemostasis was immediate and permanent. No major untoward postoperative events such as re-bleeding or infection were noted. One case developed a second-degree burn in the right elbow due to a misplaced ground conduction plate. Rectus muscle fragment welding is, in our experience, an effective and practical method of controlling presacral haemorrhage.

  7. Contributions of computational chemistry and biophysical techniques to fragment-based drug discovery.

    Science.gov (United States)

    Gozalbes, Rafael; Carbajo, Rodrigo J; Pineda-Lucena, Antonio

    2010-01-01

    In the last decade, fragment-based drug discovery (FBDD) has evolved from a novel approach in the search of new hits to a valuable alternative to the high-throughput screening (HTS) campaigns of many pharmaceutical companies. The increasing relevance of FBDD in the drug discovery universe has been concomitant with an implementation of the biophysical techniques used for the detection of weak inhibitors, e.g. NMR, X-ray crystallography or surface plasmon resonance (SPR). At the same time, computational approaches have also been progressively incorporated into the FBDD process and nowadays several computational tools are available. These stretch from the filtering of huge chemical databases in order to build fragment-focused libraries comprising compounds with adequate physicochemical properties, to more evolved models based on different in silico methods such as docking, pharmacophore modelling, QSAR and virtual screening. In this paper we will review the parallel evolution and complementarities of biophysical techniques and computational methods, providing some representative examples of drug discovery success stories by using FBDD.

  8. Twenty years on: the impact of fragments on drug discovery.

    Science.gov (United States)

    Erlanson, Daniel A; Fesik, Stephen W; Hubbard, Roderick E; Jahnke, Wolfgang; Jhoti, Harren

    2016-09-01

    After 20 years of sometimes quiet growth, fragment-based drug discovery (FBDD) has become mainstream. More than 30 drug candidates derived from fragments have entered the clinic, with two approved and several more in advanced trials. FBDD has been widely applied in both academia and industry, as evidenced by the large number of papers from universities, non-profit research institutions, biotechnology companies and pharmaceutical companies. Moreover, FBDD draws on a diverse range of disciplines, from biochemistry and biophysics to computational and medicinal chemistry. As the promise of FBDD strategies becomes increasingly realized, now is an opportune time to draw lessons and point the way to the future. This Review briefly discusses how to design fragment libraries, how to select screening techniques and how to make the most of information gleaned from them. It also shows how concepts from FBDD have permeated and enhanced drug discovery efforts.

  9. Structure-activity relationship of CART (cocaine- and amphetamine-regulated transcript) peptide fragments

    Czech Academy of Sciences Publication Activity Database

    Maixnerová, Jana; Hlaváček, Jan; Blokešová, Darja; Kowalczyk, W.; Elbert, Tomáš; Šanda, Miloslav; Blechová, Miroslava; Železná, Blanka; Slaninová, Jiřina; Maletínská, Lenka

    2007-01-01

    Roč. 28, č. 10 (2007), s. 1945-1953 ISSN 0196-9781 R&D Projects: GA ČR GA303/05/0614 Institutional research plan: CEZ:AV0Z40550506 Keywords : CART peptide * fragments * binding * PC12 cells Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.368, year: 2007

  10. Improving chemistry performance in CANDU plants

    International Nuclear Information System (INIS)

    Turner, C.; Guzonas, D.

    2010-01-01

    There is a strong interplay between coolant chemistry and materials selection in any nuclear power plant system. To achieve the design life of reactor components it is necessary to monitor and control relevant chemistry parameters, such as ionic conductivity, pH, concentrations of dissolved ions and redox species (e.g., hydrogen, hydrazine, oxygen) and the concentrations of suspended corrosion products. Chemistry specifications are set to achieve a balance between the sometimes conflicting requirements to minimize corrosion and radiological dose and to minimize operating and maintenance costs over the lifetime of the plant. For the past decade, Atomic Energy of Canada Limited (AECL) has taken a rigorous and disciplined approach to reviewing and updating all aspects of chemistry control in the CANDU® nuclear power plant (NPP). This approach has included proactively reviewing chemistry operating experience from existing CANDU® and other water-cooled NPPs worldwide to identify and address emerging issues, updating all of our chemistry control documentation to ensure that each chemistry parameter is linked to a specific requirement (e.g., reduce activity transport, monitor for condenser leak) and incorporating the latest results from our Research and Development (R and D) programs to ensure that all chemistry specifications are supported by a sound rationale. The results of this review and update have been incorporated into updated chemistry specifications and, in some cases, modified operating procedures for new and existing plants. In addition, recommendations have been made for design modifications to improve chemistry control in new build plants, especially during periods of shutdown and startup when chemistry control has traditionally been more challenging. Chemistry control in new-build CANDU® plants will rely increasingly on the use of on-line instrumentation interfaced directly to AECL's state-of-the-art chemistry monitoring, diagnostics and analysis

  11. Nuclear chemistry progress report

    International Nuclear Information System (INIS)

    Viola, V.E.; Kwiatkowski, K.

    1991-08-01

    During the past year the Nuclear Chemistry Group at Indiana University has concentrated its efforts on (1) the analysis and publication of previous experimental studies and (2) the design and construction of ISiS, a 4π detector for multifragment emission studies. No new experiments were undertaken, rather all of our experimental effort has been directed toward component tests of ISiS, with a goal of beginning measurements with this device in 1992. Research projects that have been largely completed during the last year include: (1) multiple fragment emission studies of the 0.90 and 3.6 GeV 3 He + nat Ag reaction; (2) intermediate-mass-fragment (IMF: 3 ≤ Z ≤ 15) excitation function measurements for the E/A = 20-to-100 MeV 14 N + nat Ag and 197 Au reactions, and (3) particle-particle correlation studies for the determination of space-time relationships energy collisions

  12. Synthetic study on prion protein fragments using a SPPS and native chemical ligation

    Czech Academy of Sciences Publication Activity Database

    Zawada, Z.; Šebestík, Jaroslav; Bednárová, Lucie; Bouř, Petr; Hlaváček, Jan; Stibor, Ivan

    2009-01-01

    Roč. 37, Suppl. 1 (2009), s. 44-44 ISSN 0939-4451. [International Congress on Amino Acids, Peptides and Proteins /11./. 03.08.2009-07.08.2009, Vienna] Institutional research plan: CEZ:AV0Z40550506 Keywords : prion protein * SPPS * native chemical ligation * fragments Subject RIV: CC - Organic Chemistry

  13. Chemistry in water reactors

    International Nuclear Information System (INIS)

    Hermansson, H.P.; Norring, K.

    1994-01-01

    The international conference Chemistry in Water Reactors was arranged in Nice 24-27/04/1994 by the French Nuclear Energy Society. Examples of technical program areas were primary chemistry, operational experience, fundamental studies and new technology. Furthermore there were sessions about radiation field build-up, hydrogen chemistry, electro-chemistry, condensate polishing, decontamination and chemical cleaning. The conference gave the impression that there are some areas that are going to be more important than others during the next few years to come. Cladding integrity: Professor Ishigure from Japan emphasized that cladding integrity is a subject of great concern, especially with respect to waterside corrosion, deposition and release of crud. Chemistry control: The control of the iron/nickel concentration quotient seems to be not as important as previously considered. The future operation of a nuclear power plant is going to require a better control of the water chemistry than achievable today. One example of this is solubility control via regulation in BWR. Trends in USA: means an increasing use of hydrogen, minimization of SCC/IASCC, minimization of radiation fields by thorough chemistry control, guarding fuel integrity by minimization of cladding corrosion and minimization of flow assisted corrosion. Stellite replacement: The search for replacement materials will continue. Secondary side crevice chemistry: Modeling and practical studies are required to increase knowledge about the crevice chemistry and how it develops under plant operation conditions. Inhibitors: Inhibitors for IGSCC and IGA as well for the primary- (zinc) as for the secondary side (Ti) should be studied. The effects and mode of operation of the inhibitors should be documented. Chemical cleaning: of heat transfer surfaces will be an important subject. Prophylactic cleaning at regular intervals could be one mode of operation

  14. Thermodynamics of the fuel fragmentation gas

    International Nuclear Information System (INIS)

    Perez, R.B.; Alsmiller, R.G. Jr.

    1977-01-01

    In the context of nuclear reactor safety studies, a program is in progress at ORNL whereby fuel-fragmentation situations are mocked up by the application of high-current capacitor discharges through solid UO 2 samples. The goal of the present work is to predict such quantities as the number of gas and liquid fragments and their energy distributions. The point of view adopted is that upon fragmentation, a cloud of UO 2 vapor is formed containing ''primeval'' liquid fragments which act as condensation centers. In the evolution of time, fragment growth is controlled by nucleation, coagulation and evaporation processes. Eventually, the vapor-droplet system will reach a situation in which clusters (fragments) of various sizes and UO 2 vapor will coexist in an ''association-disassociation'' equilibrium. Thus, the physical model considered here consists of the identification of the fragmentation gas with an ''imperfect'' vapor, made up of interacting UO 2 vapor and liquid fragments. The results of the study are presented

  15. Constitutional dynamic chemistry: bridge from supramolecular chemistry to adaptive chemistry.

    Science.gov (United States)

    Lehn, Jean-Marie

    2012-01-01

    Supramolecular chemistry aims at implementing highly complex chemical systems from molecular components held together by non-covalent intermolecular forces and effecting molecular recognition, catalysis and transport processes. A further step consists in the investigation of chemical systems undergoing self-organization, i.e. systems capable of spontaneously generating well-defined functional supramolecular architectures by self-assembly from their components, thus behaving as programmed chemical systems. Supramolecular chemistry is intrinsically a dynamic chemistry in view of the lability of the interactions connecting the molecular components of a supramolecular entity and the resulting ability of supramolecular species to exchange their constituents. The same holds for molecular chemistry when the molecular entity contains covalent bonds that may form and break reversibility, so as to allow a continuous change in constitution by reorganization and exchange of building blocks. These features define a Constitutional Dynamic Chemistry (CDC) on both the molecular and supramolecular levels.CDC introduces a paradigm shift with respect to constitutionally static chemistry. The latter relies on design for the generation of a target entity, whereas CDC takes advantage of dynamic diversity to allow variation and selection. The implementation of selection in chemistry introduces a fundamental change in outlook. Whereas self-organization by design strives to achieve full control over the output molecular or supramolecular entity by explicit programming, self-organization with selection operates on dynamic constitutional diversity in response to either internal or external factors to achieve adaptation.The merging of the features: -information and programmability, -dynamics and reversibility, -constitution and structural diversity, points to the emergence of adaptive and evolutive chemistry, towards a chemistry of complex matter.

  16. Reactor water chemistry control

    International Nuclear Information System (INIS)

    Kundu, A.K.

    2010-01-01

    Tarapur Atomic Power Station - 1 and 2 (TAPS) is a twin unit Boiling Water Reactors (BWRs) built in 1960's and operating presently at 160MWe. TAPS -1 and 2 are one of the vintage reactors operating in the world and belongs to earlier generation of BWRs has completed 40 years of successful, commercial and safe operation. In 1980s, both the reactors were de-rated from 660MWth to 530MWth due to leaks in the Secondary Steam Generators (SSGs). In BWR the feed water acts as the primary coolant which dissipates the fission heat and thermalises the fast neutrons generated in the core due to nuclear fission reaction and under goes boiling in the Reactor Pressure Vessel (RPV) to produce steam. Under the high reactor temperature and pressure, RPV and the primary system materials are highly susceptible to corrosion. In order to avoid local concentration of the chemicals in the RPV of BWR, chemical additives are not recommended for corrosion prevention of the system materials. So to prevent corrosion of the RPV and the primary system materials, corrosion resistant materials like stainless steel (of grade SS304, SS304L and SS316LN) is used as the structural material for most of the primary system components. In case of feed water system, main pipe lines are of carbon steel and the heater shell materials are of carbon steel lined with SS whereas the feed water heater tubes are of SS-304. In addition to the choice of materials, another equally important factor for corrosion prevention and corrosion mitigation of the system materials is maintaining highly pure water quality and strict water chemistry regime for both the feed water and the primary coolant, during operation and shutdown of the reactor. This also helps in controlled migration of corrosion product to and from the reactor core and to reduce radiation field build up across the primary system materials. Experience in this field over four decades added to the incorporation of modern techniques in detection of low

  17. Size-selected methyl lactate clusters: fragmentation and spectroscopic fingerprints of chiral recognition

    Czech Academy of Sciences Publication Activity Database

    Fárník, Michal; Weimann, M.; Steinbach, Ch.; Buck, U.; Borho, N.; Adler, T. B.; Suhm, M. A.

    2006-01-01

    Roč. 8, č. 10 (2006), s. 1148-1158 ISSN 1463-9076 Grant - others:Deutsche Forschungsgemeinschaft(DE) SFB 357; Deutsche Forschungsgemeinschaft(DE) GRK 782 Institutional research plan: CEZ:AV0Z40400503 Keywords : electron-bombardment fragmentation * methanol clusters * methanol clusters * water clusters Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.892, year: 2006

  18. Organic Chemistry in Space

    Science.gov (United States)

    Charnley, Steven

    2009-01-01

    Astronomical observations, theoretical modeling, laboratory simulation and analysis of extraterrestrial material have enhanced our knowledge of the inventory of organic matter in the interstellar medium (ISM) and on small bodies such as comets and asteroids (Ehrenfreund & Charnley 2000). Comets, asteroids and their fragments, meteorites and interplanetary dust particles (IDPs), contributed significant amounts of extraterrestrial organic matter to the young Earth. This material degraded and reacted in a terrestrial prebiotic chemistry to form organic structures that may have served as building blocks for life on the early Earth. In this talk I will summarize our current understanding of the organic composition and chemistry of interstellar clouds. Molecules of astrobiological relevance include the building blocks of our genetic material: nucleic acids, composed of subunits such as N-heterocycles (purines and pyrimidines), sugars and amino acids. Signatures indicative of inheritance of pristine and modified interstellar material in comets and meteorites will also be discussed.

  19. Hydrogen rearrangement to and from radical z fragments in electron capture dissociation of peptides

    DEFF Research Database (Denmark)

    Savitski, Mikhail M; Kjeldsen, Frank; Nielsen, Michael L

    2007-01-01

    Hydrogen rearrangement is an important process in radical chemistry. A high degree of H. rearrangement to and from z. ionic fragments (combined occurrence frequency 47% compared with that of z.) is confirmed in analysis of 15,000 tandem mass spectra of tryptic peptides obtained with electron...

  20. 76 FR 13629 - Draft Guidance for Industry on Chemistry, Manufacturing, and Controls Information-Fermentation...

    Science.gov (United States)

    2011-03-14

    ...] Draft Guidance for Industry on Chemistry, Manufacturing, and Controls Information--Fermentation-Derived... Controls (CMC) Information-- Fermentation-Derived Intermediates, Drug Substances, and Related Drug Products... documentation to submit to support the CMC information for fermentation-derived intermediates, drug substances...

  1. Fragment Length of Circulating Tumor DNA.

    Science.gov (United States)

    Underhill, Hunter R; Kitzman, Jacob O; Hellwig, Sabine; Welker, Noah C; Daza, Riza; Baker, Daniel N; Gligorich, Keith M; Rostomily, Robert C; Bronner, Mary P; Shendure, Jay

    2016-07-01

    Malignant tumors shed DNA into the circulation. The transient half-life of circulating tumor DNA (ctDNA) may afford the opportunity to diagnose, monitor recurrence, and evaluate response to therapy solely through a non-invasive blood draw. However, detecting ctDNA against the normally occurring background of cell-free DNA derived from healthy cells has proven challenging, particularly in non-metastatic solid tumors. In this study, distinct differences in fragment length size between ctDNAs and normal cell-free DNA are defined. Human ctDNA in rat plasma derived from human glioblastoma multiforme stem-like cells in the rat brain and human hepatocellular carcinoma in the rat flank were found to have a shorter principal fragment length than the background rat cell-free DNA (134-144 bp vs. 167 bp, respectively). Subsequently, a similar shift in the fragment length of ctDNA in humans with melanoma and lung cancer was identified compared to healthy controls. Comparison of fragment lengths from cell-free DNA between a melanoma patient and healthy controls found that the BRAF V600E mutant allele occurred more commonly at a shorter fragment length than the fragment length of the wild-type allele (132-145 bp vs. 165 bp, respectively). Moreover, size-selecting for shorter cell-free DNA fragment lengths substantially increased the EGFR T790M mutant allele frequency in human lung cancer. These findings provide compelling evidence that experimental or bioinformatic isolation of a specific subset of fragment lengths from cell-free DNA may improve detection of ctDNA.

  2. Rock fragment cover controls the sediment detachment in citrus plantations

    Science.gov (United States)

    Cerdà, Artemi; Keesstra, Saskia; Hamidreza Sadeghi, Seyed; Brevik, Eric; Giménez Morera, Antonio; Novara, Agata; Masto, Reginald E.; Jordán, Antonio; Wang, Juan

    2016-04-01

    Citrus orchards are seen as a source of sediments and water due to the lack of vegetation cover, the widespread use of herbicides, the compaction due to the use of heavy machinery, the lack of organic amendments and the removal of the pruned branches (Cerdà and Jurgensen, 2008; Cerdà et al., 2009; Cerdà and Jurgensen, 2011; Li et al, 2011). This is not unusual in agriculture, where high soil erosion losses are found in the orchards (Dai et al., 2015; Erkossa et al., 2015; Ochoa-Cueva et al., 2015). Therefore, there is a need to reduce the sediment delivery, and to achieve a sustainable situation with lower and renewable soil erosion rates (Cerdà et al., 2015; Nanko et al., 2015; Mwango et al., 2016). Vegetation cover is the most efficient strategy to control soil and water losses at different scales (Cerdà, 1999; Keesstra, 2007; Zhao et al., 2014), but farmers in the Mediterranean Regions prefer bare soils as this reduces the amount of water used by the plants, and also because of aesthetic concerns, as bare soils are perceived as tidy and therefore seen by farmers as the way their orchards should look. So therefore, there is a need to find an efficient strategy that reduces soil losses and will be accepted by the farmers also. One potential option for this may be to use rock fragments (stones) as a mulch to reduce the soil losses. Other researchers already found rock fragments to be an effective tool to reduce erosion (Poesen et al., 1994; Poesen and Lavee, 1994; Cerdà, 2001; Jomaa et al., 2012; Martínez Zavala and Jordán, 2008; Jordán and Martínez Zavala, 2008; Jordán et al., 2009; Zavala et al., 2010). Furthermore, rock fragments can improve soil quality and contribute to the restoration of ecosystems (Jiménez et al., 2015). However, most previous research on soil erosion and rock fragment cover was done under laboratory conditions or in forest soils. Meanwhile, little is known about the role of rock fragments in agriculture land under field

  3. Experimental Studies on Improved Plastic Bonded Explosives Materials (PBXs for Controlled Fragmentation Warheads

    Directory of Open Access Journals (Sweden)

    Elsharkawy Karim

    2017-01-01

    Full Text Available This paper describes formulations of plastic bonded explosives (PBXs based on three highly brisant explosives, namely 1,3,5-trinitro-1,3,5-triazinane (RDX, 1,3,5,7-tetranitro-1,3,5,7-tetrazocane (HMX and pentaerythritoltetranitrate (PETN with polyurethane (PU based on Glycidyl azide polymer (GAP as an energetic binder in comparison with composition-B, which used in the fragmentation warheads. The sensitivity and performance properties of different types of PBXs were evaluated by experimental results of prepared selected PBX compositions. Casting technique was used to prepare the selected compositions containing 14% PU based on GAP. It has been observed that the brisance of the PBX based on HMX was higher than that of comp-B by 21.3 %, the detonation velocity showed a remarkable increase of the order of 8480 (m/s while that of comp-B was 7638 (m/s. A controlled fragmentation warhead with an outer grooving warhead case of dimensions 100x35x4 mm was used and arena test was carried out to determine the lethal zone of the fragmentation warhead. The lethal zone obtained from arena test for PBX composition based on HMX named PBXHG4 was higher than that based on RDX or PETN, and than that of comp-B by 40%.

  4. Operating experience in correcting severe secondary chemistry upsets by controlling makeup water organics (TOC)

    International Nuclear Information System (INIS)

    Flint, W.G.; Mc Intosh, R.J.

    1986-01-01

    In this paper following observations are presented: conductivity and chloride excursions in steam condensate were directly linked to makeup water quality. Data strongly suggests that the breakdown of makeup water organics was responsible for substandard condensate water quality; although the short-term effects of gross organic contamination have been documented, the longer term consequences of continuous exposure by moderate organic levels needs to be addressed; a greater understanding of the organic removal efficiency of the various water purification technologies is essential to controlling TOC contamination; and a much better understanding of makeup plant chemistry and the interrelationship of makeup water contamination and plant chemistry has proven essential to optimizing plant performance and guaranteeing the best possible steam chemistry. The role of the chemistry group as an active participant in operations has been proven at Kewaunee Nuclear Plant

  5. Controls on dripwater chemistry of Oregon Caves National Monument, northwestern United States

    Science.gov (United States)

    Rushdi, Ahmed I.; Ersek, Vasile; Mix, Alan C.; Clark, Peter U.

    2018-02-01

    Cave dripwater chemistry of Oregon Caves National Monument (OCNM) was studied, where the parameters pH, total alkalinity, calcium, magnesium, strontium, sodium and barium were analyzed at quasi-monthly intervals from 2005 to 2007. Different statistical analyses have been used to investigate the variability of the chemical parameters in the different sites in the OCNM cave system. The dripwater varies in response to seasonal changes in rainfall. The drip rates range from zero in summer to continuous flow in winter, closely following the rainfall intensity. Spatial variations of dripwater chemistry, which is nonlinearly related to dripwater discharge likely, reflect the chemical composition of bedrock and overlying soil, and the residence time of the ground water within the aquifer. The residence time of infiltrated water in bedrock cracks control the dissolution carbonate bedrock, reprecipitation of calcium carbonate and the degree of saturation of dripwater with respect to calcium carbonate minerals. Spatiotemporal fluctuations of dripwater Mg/Ca and Sr/Ca ratios are controlled by dissolution of carbonate bedrock and the degree of calcite reprecipitation in bedrock cracks. This suggests that trace elements in speleothem deposits at the OCNM may serve as paleoclimatological proxies for precipitation, if interpreted within the context of understanding local bedrock chemistry.

  6. Technical Basis for Water Chemistry Control of IGSCC in Boiling Water Reactors

    Science.gov (United States)

    Gordon, Barry; Garcia, Susan

    Boiling water reactors (BWRs) operate with very high purity water. However, even the utilization of near theoretical conductivity water cannot prevent intergranular stress corrosion cracking (IGSCC) of sensitized stainless steel, wrought nickel alloys and nickel weld metals under oxygenated conditions. IGSCC can be further accelerated by the presence of certain impurities dissolved in the coolant. The goal of this paper is to present the technical basis for controlling various impurities under both oxygenated, i.e., normal water chemistry (NWC) and deoxygenated, i.e., hydrogen water chemistry (HWC) conditions for mitigation of IGSCC. More specifically, the effects of typical BWR ionic impurities (e.g., sulfate, chloride, nitrate, borate, phosphate, etc.) on IGSCC propensities in both NWC and HWC environments will be discussed. The technical basis for zinc addition to the BWR coolant will also provided along with an in-plant example of the most severe water chemistry transient to date.

  7. Water Chemistry Control Technology to Improve the Performance of Nuclear Power Plants for Extended Fuel Cycles

    International Nuclear Information System (INIS)

    Maeng, W. Y.; Na, J. W.; Lee, E. H.

    2010-07-01

    Ο To Develop the technology to manage the problems of AOA and radiation, corrosion as long term PWR operation. Ο To Establish the advanced water chemical operating systems. - Development of the proper water chemistry guidelines for long term PWR operation. AOA(Axial Offest Anomaly) has been reported in many PWR plants in the world, including Korea, especially in the plants of higher burn-up and longer cycle operation or power up-rate. A test loop has been designed and made by KAERI, in order to investigate and mitigate AOA problems in Korea. This project included the study of hydrodynamic simulation and the modeling about AOA. The analysis of radioactive crud was performed to investigate of NPPs primary water chemical effect on AOA and to reduce the radioactive dose rate. The high temperature measurement system was developed to on-line monitor of water chemistry in nuclear power plants. The effects of various environmental factors such as temperature, pressure, and flow rate on YSZ-based pH electrode were evaluated for ensuring the accuracy of high-temperature pH measurement. The inhibition technology for fouling and SCC of SG tube was evaluated to establish the water chemistry technology of corrosion control of nuclear system. The high temperature and high pressure crevice chemistry analysis test loop was manufactured to develop the water chemistry technology of crevice chemistry control

  8. Automated building of organometallic complexes from 3D fragments.

    Science.gov (United States)

    Foscato, Marco; Venkatraman, Vishwesh; Occhipinti, Giovanni; Alsberg, Bjørn K; Jensen, Vidar R

    2014-07-28

    A method for the automated construction of three-dimensional (3D) molecular models of organometallic species in design studies is described. Molecular structure fragments derived from crystallographic structures and accurate molecular-level calculations are used as 3D building blocks in the construction of multiple molecular models of analogous compounds. The method allows for precise control of stereochemistry and geometrical features that may otherwise be very challenging, or even impossible, to achieve with commonly available generators of 3D chemical structures. The new method was tested in the construction of three sets of active or metastable organometallic species of catalytic reactions in the homogeneous phase. The performance of the method was compared with those of commonly available methods for automated generation of 3D models, demonstrating higher accuracy of the prepared 3D models in general, and, in particular, a much wider range with respect to the kind of chemical structures that can be built automatically, with capabilities far beyond standard organic and main-group chemistry.

  9. Analysis of human blood plasma cell-free DNA fragment size distribution using EvaGreen chemistry based droplet digital PCR assays.

    Science.gov (United States)

    Fernando, M Rohan; Jiang, Chao; Krzyzanowski, Gary D; Ryan, Wayne L

    2018-04-12

    Plasma cell-free DNA (cfDNA) fragment size distribution provides important information required for diagnostic assay development. We have developed and optimized droplet digital PCR (ddPCR) assays that quantify short and long DNA fragments. These assays were used to analyze plasma cfDNA fragment size distribution in human blood. Assays were designed to amplify 76,135, 490 and 905 base pair fragments of human β-actin gene. These assays were used for fragment size analysis of plasma cell-free, exosome and apoptotic body DNA obtained from normal and pregnant donors. The relative percentages for 76, 135, 490 and 905 bp fragments from non-pregnant plasma and exosome DNA were 100%, 39%, 18%, 5.6% and 100%, 40%, 18%,3.3%, respectively. The relative percentages for pregnant plasma and exosome DNA were 100%, 34%, 14%, 23%, and 100%, 30%, 12%, 18%, respectively. The relative percentages for non-pregnant plasma pellet (obtained after 2nd centrifugation step) were 100%, 100%, 87% and 83%, respectively. Non-pregnant Plasma cell-free and exosome DNA share a unique fragment distribution pattern which is different from pregnant donor plasma and exosome DNA fragment distribution indicating the effect of physiological status on cfDNA fragment size distribution. Fragment distribution pattern for plasma pellet that includes apoptotic bodies and nuclear DNA was greatly different from plasma cell-free and exosome DNA. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

  10. Technetium chemistry

    International Nuclear Information System (INIS)

    Burns, C.; Bryan, J.; Cotton, F.; Ott, K.; Kubas, G.; Haefner, S.; Barrera, J.; Hall, K.; Burrell, A.

    1996-01-01

    Technetium chemistry is a young and developing field. Despite the limited knowledge of its chemistry, technetium is the workhorse for nuclear medicine. Technetium is also a significant environmental concern because it is formed as a byproduct of nuclear weapons production and fission-power generators. Development of new technetium radio-pharmaceuticals and effective environmental control depends strongly upon knowledge of basic technetium chemistry. The authors performed research into the basic coordination and organometallic chemistry of technetium and used this knowledge to address nuclear medicine and environmental applications. This is the final report of a three-year Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL)

  11. Microstructural characterization of pipe bomb fragments

    International Nuclear Information System (INIS)

    Gregory, Otto; Oxley, Jimmie; Smith, James; Platek, Michael; Ghonem, Hamouda; Bernier, Evan; Downey, Markus; Cumminskey, Christopher

    2010-01-01

    Recovered pipe bomb fragments, exploded under controlled conditions, have been characterized using scanning electron microscopy, optical microscopy and microhardness. Specifically, this paper examines the microstructural changes in plain carbon-steel fragments collected after the controlled explosion of galvanized, schedule 40, continuously welded, steel pipes filled with various smokeless powders. A number of microstructural changes were observed in the recovered pipe fragments: deformation of the soft alpha-ferrite grains, deformation of pearlite colonies, twin formation, bands of distorted pearlite colonies, slip bands, and cross-slip bands. These microstructural changes were correlated with the relative energy of the smokeless powder fillers. The energy of the smokeless powder was reflected in a reduction in thickness of the pipe fragments (due to plastic strain prior to fracture) and an increase in microhardness. Moreover, within fragments from a single pipe, there was a radial variation in microhardness, with the microhardness at the outer wall being greater than that at the inner wall. These findings were consistent with the premise that, with the high energy fillers, extensive plastic deformation and wall thinning occurred prior to pipe fracture. Ultimately, the information collected from this investigation will be used to develop a database, where the fragment microstructure and microhardness will be correlated with type of explosive filler and bomb design. Some analyses, specifically wall thinning and microhardness, may aid in field characterization of explosive devices.

  12. The Complex Stratigraphy of the Highland Crust in the Serenitatis Region of the Moon Inferred from Mineral Fragment Chemistry

    Science.gov (United States)

    Ryder, Graham; Norman, Marc D.; Taylor, G. Jeffrey

    1997-01-01

    Large impact basins are natural drill holes into the Moon, and their ejecta carries unique information about the rock types and stratigraphy of the lunar crust. We have conducted an electron microprobe study of mineral fragments in the poikilitic melt breccias collected from the Taurus Mountains at the Apollo 17 landing site. These breccias are virtually unanimously agreed to be impact melt produced in the Serenitatis impact event. They contain lithic fragments and much more abundant mineral fragments of crustal origin. We have made precise microprobe analyses of minor element abundances in fragments of olivine, pyroxene, and plagioclase to provide new information on the possible source rocks and the crustal stratigraphy in the Serenitatis region. These data were also intended to elucidate the nature of the cryptic geochemical component in breccias such as these with low-K Fra Mauro basalt compositions. We chose the finest-grained (i.e., most rapidly quenched) breccias for study, to avoid reacted and partly assimilated fragments as much as possible. Most of the mineral fragments appear to have been derived from rocks that would fall into the pristine igneous Mg-suite as represented by lithic fragments in the Apollo collection, or reasonable extensions of it. Gabbroic rocks were more abundant in the target stratigraphy than is apparent from the Apollo sample collection. Some pyroxene and plagiociase, but probably not much olivine, could be derived from feldspathic granulites, which are metamorphosed polymict breccias. Some mineral fragments are from previously unknown rocks. These include highly magnesian olivines (up to Fo(sub 94)), possibly volcanic in origin, that exacerbate the difficulty in explaining highly magnesian rocks in the lunar crust. It appears that some part of the lunar interior has an mg*(= 100 x Mg/(Mg/Fe) atomic) greater than the conventional bulk Moon value of 80-84. Other volcanic rocks, including mare basalts, and rapidly- cooled impact melt

  13. Flow chemistry to control the synthesis of nano and microparticles for biomedical applications.

    Science.gov (United States)

    Hassan, Natalia; Oyarzun-Ampuero, Felipe; Lara, Pablo; Guerrero, Simón; Cabuil, Valérie; Abou-Hassan, Ali; Kogan, Marcelo J

    2014-03-01

    In this article we review the flow chemistry methodologies for the controlled synthesis of different kind of nano and microparticles for biomedical applications. Injection mechanism has emerged as new alternative for the synthesis of nanoparticles due to this strategy allows achieving superior levels of control of self-assemblies, leading to higher-ordered structures and rapid chemical reactions. Self-assembly events are strongly dependent on factors such as the local concentration of reagents, the mixing rates, and the shear forces, which can be finely tuned, as an example, in a microfluidic device. Injection methods have also proved to be optimal to elaborate microsystems comprising polymer solutions. Concretely, extrusion based methods can provide controlled fluid transport, rapid chemical reactions, and cost-saving advantages over conventional reactors. We provide an update of synthesis of nano and microparticles such as core/shell, Janus, nanocrystals, liposomes, and biopolymeric microgels through flow chemistry, its potential bioapplications and future challenges in this field are discussed.

  14. Physics and chemistry of plasma pollution control technology

    International Nuclear Information System (INIS)

    Chang, J S

    2008-01-01

    Gaseous pollution control technologies for acid gases (NO x , SO x , etc), volatile organic compounds, greenhouse gases, ozone layer depleting substances, etc have been commercialized based on catalysis, incineration and adsorption methods. However, non-thermal plasma techniques based on electron beams and corona discharges are becoming significant due to advantages such as lower costs, higher removal efficiency and smaller space volume. In order to commercialize this new technology, the pollution gas removal rate, energy efficiency of removal, pressure drop of reactors and useable by-product production rates must be improved and identification of major fundamental processes and optimizations of reactor and power supply for an integrated system must be investigated. In this work, the chemistry and physics of plasma pollution control are discussed and the limitation of this type of plasma is outlined based on the plasma parameters.

  15. Bespoke Fragments

    DEFF Research Database (Denmark)

    Kruse Aagaard, Anders

    2016-01-01

    , investigating levels of control and uncertainty encountering with these. Through tangible experiments, the project discusses materiality and digitally controlled fabrications tools as direct expansions of the architect's digital drawing and workflow. The project sees this expansion as an opportunity to connect...... architectural designs, tectonics and aesthetics. In this Ph.D.-project a series a physical, but conceptual, experiment plays the central role in the knowledge production. The experiments result in materialised architectural fragments and tangible experiences. However, these creations also become the driving...

  16. Fragment-based lead generation: identification of seed fragments by a highly efficient fragment screening technology

    Science.gov (United States)

    Neumann, Lars; Ritscher, Allegra; Müller, Gerhard; Hafenbradl, Doris

    2009-08-01

    For the detection of the precise and unambiguous binding of fragments to a specific binding site on the target protein, we have developed a novel reporter displacement binding assay technology. The application of this technology for the fragment screening as well as the fragment evolution process with a specific modelling based design strategy is demonstrated for inhibitors of the protein kinase p38alpha. In a fragment screening approach seed fragments were identified which were then used to build compounds from the deep-pocket towards the hinge binding area of the protein kinase p38alpha based on a modelling approach. BIRB796 was used as a blueprint for the alignment of the fragments. The fragment evolution of these deep-pocket binding fragments towards the fully optimized inhibitor BIRB796 included the modulation of the residence time as well as the affinity. The goal of our study was to evaluate the robustness and efficiency of our novel fragment screening technology at high fragment concentrations, compare the screening data with biochemical activity data and to demonstrate the evolution of the hit fragments with fast kinetics, into slow kinetic inhibitors in an in silico approach.

  17. Controlled fragmentation of multimaterial fibres and films via polymer cold-drawing.

    Science.gov (United States)

    Shabahang, Soroush; Tao, Guangming; Kaufman, Joshua J; Qiao, Yangyang; Wei, Lei; Bouchenot, Thomas; Gordon, Ali P; Fink, Yoel; Bai, Yuanli; Hoy, Robert S; Abouraddy, Ayman F

    2016-06-23

    Polymer cold-drawing is a process in which tensile stress reduces the diameter of a drawn fibre (or thickness of a drawn film) and orients the polymeric chains. Cold-drawing has long been used in industrial applications, including the production of flexible fibres with high tensile strength such as polyester and nylon. However, cold-drawing of a composite structure has been less studied. Here we show that in a multimaterial fibre composed of a brittle core embedded in a ductile polymer cladding, cold-drawing results in a surprising phenomenon: controllable and sequential fragmentation of the core to produce uniformly sized rods along metres of fibre, rather than the expected random or chaotic fragmentation. These embedded structures arise from mechanical-geometric instabilities associated with 'neck' propagation. Embedded, structured multimaterial threads with complex transverse geometry are thus fragmented into a periodic train of rods held stationary in the polymer cladding. These rods can then be easily extracted via selective dissolution of the cladding, or can self-heal by thermal restoration to re-form the brittle thread. Our method is also applicable to composites with flat rather than cylindrical geometries, in which case cold-drawing leads to the break-up of an embedded or coated brittle film into narrow parallel strips that are aligned normally to the drawing axis. A range of materials was explored to establish the universality of this effect, including silicon, germanium, gold, glasses, silk, polystyrene, biodegradable polymers and ice. We observe, and verify through nonlinear finite-element simulations, a linear relationship between the smallest transverse scale and the longitudinal break-up period. These results may lead to the development of dynamical and thermoreversible camouflaging via a nanoscale Venetian-blind effect, and the fabrication of large-area structured surfaces that facilitate high-sensitivity bio-detection.

  18. [Electrocoagulation on a fragment of anterior abdominal rectal muscle for the control of presacral bleeding during rectal resection].

    Science.gov (United States)

    Casal Núñez, José Enrique; Martínez, María Teresa García; Poblador, Alejandro Ruano

    2012-03-01

    Presacral venous haemorrhage during rectal movement is low, but is often massive, and even fatal. Our objective is the "in vitro" determination of the results of electrocoagulation applied to a fragment of muscle on the sacral bone surface during rectal resection due to a malignant neoplasm of the rectum. Single-pole coagulation was applied "in vitro" with the selector at maximum power on a 2×2 cms muscle fragment, applied to the anterior side of the IV sacral vertebra until reaching boiling point. The method was used on 6 patients with bleeding of the presacral venous plexus. In the "in vitro" study, boiling point was reached in 90 seconds from applying the single-pole current on the muscle fragment. Electrocoagulation was applied to a 2×2 cm rectal muscle fragment in 6 patients with presacral venous haemorrhage, using pressure on the surface of the presacral bone, with the stopping of the bleeding being achieved in all cases. The use of indirect electrocoagulation on a fragment of the rectus abdominis muscle is a straightforward and highly effective technique for controlling presacral venous haemorrhage. Copyright © 2011 AEC. Published by Elsevier Espana. All rights reserved.

  19. A Bioinorganic Approach to Fragment-Based Drug Discovery Targeting Metalloenzymes.

    Science.gov (United States)

    Cohen, Seth M

    2017-08-15

    Metal-dependent enzymes (i.e., metalloenzymes) make up a large fraction of all enzymes and are critically important in a wide range of biological processes, including DNA modification, protein homeostasis, antibiotic resistance, and many others. Consequently, metalloenzymes represent a vast and largely untapped space for drug development. The discovery of effective therapeutics that target metalloenzymes lies squarely at the interface of bioinorganic and medicinal chemistry and requires expertise, methods, and strategies from both fields to mount an effective campaign. In this Account, our research program that brings together the principles and methods of bioinorganic and medicinal chemistry are described, in an effort to bridge the gap between these fields and address an important class of medicinal targets. Fragment-based drug discovery (FBDD) is an important drug discovery approach that is particularly well suited for metalloenzyme inhibitor development. FBDD uses relatively small but diverse chemical structures that allow for the assembly of privileged molecular collections that focus on a specific feature of the target enzyme. For metalloenzyme inhibition, the specific feature is rather obvious, namely, a metal-dependent active site. Surprisingly, prior to our work, the exploration of diverse molecular fragments for binding the metal active sites of metalloenzymes was largely unexplored. By assembling a modest library of metal-binding pharmacophores (MBPs), we have been able to find lead hits for many metalloenzymes and, from these hits, develop inhibitors that act via novel mechanisms of action. A specific case study on the use of this strategy to identify a first-in-class inhibitor of zinc-dependent Rpn11 (a component of the proteasome) is highlighted. The application of FBDD for the development of metalloenzyme inhibitors has raised several other compelling questions, such as how the metalloenzyme active site influences the coordination chemistry of bound

  20. Material effect in the nuclear fuel-coolant interaction: Analyses of prototypic melt fragmentation and solidification in the KROTOS facility

    Czech Academy of Sciences Publication Activity Database

    Tyrpekl, V.; Piluso, P.; Bakardjieva, Snejana; Dugne, O.

    2014-01-01

    Roč. 186, č. 2 (2014), s. 229-240 ISSN 0029-5450 Institutional support: RVO:61388980 Keywords : fuel-coolant interaction * melt fragmentation * KROTOS facility Subject RIV: CA - Inorganic Chemistry Impact factor: 0.725, year: 2014

  1. WHAT IS CONTROLLING THE FRAGMENTATION IN THE INFRARED DARK CLOUD G14.225–0.506?: DIFFERENT LEVELS OF FRAGMENTATION IN TWIN HUBS

    Energy Technology Data Exchange (ETDEWEB)

    Busquet, Gemma; Girart, Josep Miquel [Institut de Ciències de l’Espai (CSIC-IEEC), Campus UAB, Carrer de Can Magrans, S/N, E-08193, Cerdanyola del Vallès, Catalunya (Spain); Estalella, Robert [Departament d’Astronomia i Meteorologia, Institut de Ciències del Cosmos (ICC), Universitat de Barcelona (IEEC-UB), Martí i Franquès, 1, E-08028 Barcelona, Catalunya (Spain); Palau, Aina [Instituto de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, P.O. Box 3-72, 58090 Morelia, Michoacán, México (Mexico); Liu, Hauyu Baobab; Ho, Paul T. P. [Academia Sinica Institute of Astronomy and Astrophysics, Taipei, Taiwan (China); Zhang, Qizhou [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); De Gregorio-Monsalvo, Itziar [European Southern Observatory (ESO), Karl-Schwarzschild-Str. 2, D-85748 Garching (Germany); Pillai, Thushara [Max Planck Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Anglada, Guillem, E-mail: busquet@ice.cat [Instituto de Astrofísica de Andalucía, CSIC, Glorieta de la Astronomía, s/n, E-18008, Granada (Spain)

    2016-03-20

    We present observations of the 1.3 mm continuum emission toward hub-N and hub-S of the infrared dark cloud G14.225–0.506 carried out with the Submillimeter Array, together with observations of the dust emission at 870 and 350 μm obtained with APEX and CSO telescopes. The large-scale dust emission of both hubs consists of a single peaked clump elongated in the direction of the associated filament. At small scales, the SMA images reveal that both hubs fragment into several dust condensations. The fragmentation level was assessed under the same conditions and we found that hub-N presents 4 fragments while hub-S is more fragmented, with 13 fragments identified. We studied the density structure by means of a simultaneous fit of the radial intensity profile at 870 and 350 μm and the spectral energy distribution adopting a Plummer-like function to describe the density structure. The parameters inferred from the model are remarkably similar in both hubs, suggesting that density structure could not be responsible for determining the fragmentation level. We estimated several physical parameters, such as the level of turbulence and the magnetic field strength, and we found no significant differences between these hubs. The Jeans analysis indicates that the observed fragmentation is more consistent with thermal Jeans fragmentation compared with a scenario in which turbulent support is included. The lower fragmentation level observed in hub-N could be explained in terms of stronger UV radiation effects from a nearby H ii region, evolutionary effects, and/or stronger magnetic fields at small scales, a scenario that should be further investigated.

  2. WHAT IS CONTROLLING THE FRAGMENTATION IN THE INFRARED DARK CLOUD G14.225–0.506?: DIFFERENT LEVELS OF FRAGMENTATION IN TWIN HUBS

    International Nuclear Information System (INIS)

    Busquet, Gemma; Girart, Josep Miquel; Estalella, Robert; Palau, Aina; Liu, Hauyu Baobab; Ho, Paul T. P.; Zhang, Qizhou; De Gregorio-Monsalvo, Itziar; Pillai, Thushara; Anglada, Guillem

    2016-01-01

    We present observations of the 1.3 mm continuum emission toward hub-N and hub-S of the infrared dark cloud G14.225–0.506 carried out with the Submillimeter Array, together with observations of the dust emission at 870 and 350 μm obtained with APEX and CSO telescopes. The large-scale dust emission of both hubs consists of a single peaked clump elongated in the direction of the associated filament. At small scales, the SMA images reveal that both hubs fragment into several dust condensations. The fragmentation level was assessed under the same conditions and we found that hub-N presents 4 fragments while hub-S is more fragmented, with 13 fragments identified. We studied the density structure by means of a simultaneous fit of the radial intensity profile at 870 and 350 μm and the spectral energy distribution adopting a Plummer-like function to describe the density structure. The parameters inferred from the model are remarkably similar in both hubs, suggesting that density structure could not be responsible for determining the fragmentation level. We estimated several physical parameters, such as the level of turbulence and the magnetic field strength, and we found no significant differences between these hubs. The Jeans analysis indicates that the observed fragmentation is more consistent with thermal Jeans fragmentation compared with a scenario in which turbulent support is included. The lower fragmentation level observed in hub-N could be explained in terms of stronger UV radiation effects from a nearby H ii region, evolutionary effects, and/or stronger magnetic fields at small scales, a scenario that should be further investigated

  3. Novel approach of fragment-based lead discovery applied to renin inhibitors.

    Science.gov (United States)

    Tawada, Michiko; Suzuki, Shinkichi; Imaeda, Yasuhiro; Oki, Hideyuki; Snell, Gyorgy; Behnke, Craig A; Kondo, Mitsuyo; Tarui, Naoki; Tanaka, Toshimasa; Kuroita, Takanobu; Tomimoto, Masaki

    2016-11-15

    A novel approach was conducted for fragment-based lead discovery and applied to renin inhibitors. The biochemical screening of a fragment library against renin provided the hit fragment which showed a characteristic interaction pattern with the target protein. The hit fragment bound only to the S1, S3, and S3 SP (S3 subpocket) sites without any interactions with the catalytic aspartate residues (Asp32 and Asp215 (pepsin numbering)). Prior to making chemical modifications to the hit fragment, we first identified its essential binding sites by utilizing the hit fragment's substructures. Second, we created a new and smaller scaffold, which better occupied the identified essential S3 and S3 SP sites, by utilizing library synthesis with high-throughput chemistry. We then revisited the S1 site and efficiently explored a good building block attaching to the scaffold with library synthesis. In the library syntheses, the binding modes of each pivotal compound were determined and confirmed by X-ray crystallography and the library was strategically designed by structure-based computational approach not only to obtain a more active compound but also to obtain informative Structure Activity Relationship (SAR). As a result, we obtained a lead compound offering synthetic accessibility as well as the improved in vitro ADMET profiles. The fragments and compounds possessing a characteristic interaction pattern provided new structural insights into renin's active site and the potential to create a new generation of renin inhibitors. In addition, we demonstrated our FBDD strategy integrating highly sensitive biochemical assay, X-ray crystallography, and high-throughput synthesis and in silico library design aimed at fragment morphing at the initial stage was effective to elucidate a pocket profile and a promising lead compound. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Fuel Chemistry Research | Transportation Research | NREL

    Science.gov (United States)

    Fuel Chemistry Research Fuel Chemistry Research Photo of a hand holding a beaker containing a clear oils. Photo by Dennis Schroeder, NREL NREL's fuel chemistry research explores how biofuels, advanced , emissions control catalysts, and infrastructure materials. Results from NREL's fuel chemistry studies feed

  5. 1st Joint European Conference on Therapeutic Targets and Medicinal Chemistry (TTMC 2015)

    Science.gov (United States)

    Le Borgne, Marc; Haidar, Samer; Duval, Olivier; Wünsch, Bernhard; Jose, Joachim

    2015-01-01

    The European Conference on Therapeutic Targets and Medicinal Chemistry is a new two-day meeting on drug discovery that is focused on therapeutic targets and the use of tools to explore all fields of drug discovery and drug design such as molecular modelling, bioorganic chemistry, NMR studies, fragment screening, in vitro assays, in vivo assays, structure activity relationships, autodisplay. Abstracts of keynote lectures, plenary lectures, junior lectures, flash presentations, and posters presented during the meeting are collected in this report. PMID:26712767

  6. Enhancing prospective chemistry teachers cognitive structures in the topics of bonding and hybridization by internet-assisted chemistry applications

    Directory of Open Access Journals (Sweden)

    Özge Özyalçın Oskay, Sinem Dinçol

    2011-08-01

    Full Text Available The purpose of this study is to determine the effects of internet-assisted chemistry applications on prospective chemistry teachers’ cognitive structures in the topics of bonding and hybridization. The sample of the study consisted of 36 prospective chemistry teachers attending Hacettepe University, Faculty of Education, the Department of Chemistry Education in 2010-2011 academic year and taking Basic Chemistry I lesson. In the study, students were separated into experimental and control groups according to their pre-cognitive structures. Students were requested to answer two open ended questions. Answers by each student were gathered and evaluated by flow map method. “Bonding and hybridization” topics were taught to control group with traditional teaching method and to experimental group besides traditional method internet-assisted applications were conducted. The same open-ended questions were given to both groups and their cognitive structures were examined once more. The differences between control and experimental groups’ cognitive structures were examined. A significant difference was identified in favour of experimental group (p<0, 05. The mean score of the Experimental group was X=19.94, and the mean score of the Control group was X=13.88. In addition, subsequent to internet assisted chemistry applications differences in terms of concepts and descriptions in prospective chemistry teachers’ in experimental and control group cognitive structure have been determined. When post flow maps of prospective chemistry teachers in experimental group, on whom internet assisted chemistry applications were made, are formed, it has been determined that there are more statements about hybridization, hybridization types, molecule geometry and bond angles compared to control grou

  7. Virtual fragment preparation for computational fragment-based drug design.

    Science.gov (United States)

    Ludington, Jennifer L

    2015-01-01

    Fragment-based drug design (FBDD) has become an important component of the drug discovery process. The use of fragments can accelerate both the search for a hit molecule and the development of that hit into a lead molecule for clinical testing. In addition to experimental methodologies for FBDD such as NMR and X-ray Crystallography screens, computational techniques are playing an increasingly important role. The success of the computational simulations is due in large part to how the database of virtual fragments is prepared. In order to prepare the fragments appropriately it is necessary to understand how FBDD differs from other approaches and the issues inherent in building up molecules from smaller fragment pieces. The ultimate goal of these calculations is to link two or more simulated fragments into a molecule that has an experimental binding affinity consistent with the additive predicted binding affinities of the virtual fragments. Computationally predicting binding affinities is a complex process, with many opportunities for introducing error. Therefore, care should be taken with the fragment preparation procedure to avoid introducing additional inaccuracies.This chapter is focused on the preparation process used to create a virtual fragment database. Several key issues of fragment preparation which affect the accuracy of binding affinity predictions are discussed. The first issue is the selection of the two-dimensional atomic structure of the virtual fragment. Although the particular usage of the fragment can affect this choice (i.e., whether the fragment will be used for calibration, binding site characterization, hit identification, or lead optimization), general factors such as synthetic accessibility, size, and flexibility are major considerations in selecting the 2D structure. Other aspects of preparing the virtual fragments for simulation are the generation of three-dimensional conformations and the assignment of the associated atomic point charges.

  8. Advances in BWR water chemistry

    International Nuclear Information System (INIS)

    Garcia, Susan E.; Giannelli, Joseph F.; Jarvis, Mary L.

    2012-09-01

    This paper reviews recent advances in Boiling Water Reactor (BWR) water chemistry control with examples of plant experiences at U.S. designed BWRs. Water chemistry advances provide some of the most effective methods for mitigating materials degradation, reducing fuel performance concerns and lowering radiation fields. Mitigation of stress corrosion cracking (SCC) of materials remains a high priority and improved techniques that have been demonstrated in BWRs will be reviewed, specifically hydrogen injection combined with noble metal chemical addition (NMCA) and the newer on-line noble metal application process (OLNC). Hydrogen injection performance, an important part of SCC mitigation, will also be reviewed for the BWR fleet, highlighting system improvements that have enabled earlier injection of hydrogen including the potential for hydrogen injection during plant startup. Water chemistry has been significantly improved by the application of pre-filtration and optimized use of ion exchange resins in the CP (condensate polishing) and reactor water cleanup (RWCU) systems. EPRI has monitored and supported water treatment improvements to meet water chemistry goals as outlined in the EPRI BWR Water Chemistry Guidelines, particularly those for SCC mitigation of reactor internals and piping, minimization of fuel risk due to corrosion and crud deposits and chemistry control for radiation field reduction. In recent years, a significant reduction has occurred in feedwater corrosion product input, particularly iron. A large percentage of plants are now reporting <0.1 ppb feedwater iron. The impacts to plant operation and chemistry of lower feedwater iron will be explored. Depleted zinc addition is widely practiced across the fleet and the enhanced focus on radiation reduction continues to emphasize the importance of controlling radiation source term. In addition, shutdown chemistry control is necessary to avoid excessive release of activated corrosion products from fuel

  9. DOE fundamentals handbook: Chemistry

    International Nuclear Information System (INIS)

    1993-01-01

    This handbook was developed to assist nuclear facility operating contractors in providing operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding of chemistry. This volume contains the following modules: reactor water chemistry (effects of radiation on water chemistry, chemistry parameters), principles of water treatment (purpose; treatment processes [ion exchange]; dissolved gases, suspended solids, and pH control; water purity), and hazards of chemicals and gases (corrosives [acids, alkalies], toxic compounds, compressed gases, flammable/combustible liquids)

  10. The use of many-body expansions and geometry optimizations in fragment-based methods.

    Science.gov (United States)

    Fedorov, Dmitri G; Asada, Naoya; Nakanishi, Isao; Kitaura, Kazuo

    2014-09-16

    Conspectus Chemists routinely work with complex molecular systems: solutions, biochemical molecules, and amorphous and composite materials provide some typical examples. The questions one often asks are what are the driving forces for a chemical phenomenon? How reasonable are our views of chemical systems in terms of subunits, such as functional groups and individual molecules? How can one quantify the difference in physicochemical properties of functional units found in a different chemical environment? Are various effects on functional units in molecular systems additive? Can they be represented by pairwise potentials? Are there effects that cannot be represented in a simple picture of pairwise interactions? How can we obtain quantitative values for these effects? Many of these questions can be formulated in the language of many-body effects. They quantify the properties of subunits (fragments), referred to as one-body properties, pairwise interactions (two-body properties), couplings of two-body interactions described by three-body properties, and so on. By introducing the notion of fragments in the framework of quantum chemistry, one obtains two immense benefits: (a) chemists can finally relate to quantum chemistry, which now speaks their language, by discussing chemically interesting subunits and their interactions and (b) calculations become much faster due to a reduced computational scaling. For instance, the somewhat academic sounding question of the importance of three-body effects in water clusters is actually another way of asking how two hydrogen bonds affect each other, when they involve three water molecules. One aspect of this is the many-body charge transfer (CT), because the charge transfers in the two hydrogen bonds are coupled to each other (not independent). In this work, we provide a generalized view on the use of many-body expansions in fragment-based methods, focusing on the general aspects of the property expansion and a contraction of a

  11. Pore chemistry and size control in hybrid porous materials for acetylene capture from ethylene

    KAUST Repository

    Cui, X.; Chen, K.; Xing, H.; Yang, Q.; Krishna, R.; Bao, Z.; Wu, H.; Zhou, W.; Dong, Xinglong; Han, Y.; Li, B.; Ren, Q.; Zaworotko, M. J.; Chen, B.

    2016-01-01

    The trade-off between physical adsorption capacity and selectivity of porous materials is a major barrier for efficient gas separation and purification through physisorption. We report control over pore chemistry and size in metal coordination

  12. Impact failure and fragmentation properties of metals

    Energy Technology Data Exchange (ETDEWEB)

    Grady, D.E. [Applied Research Associates, Albuquerque, NM (United States); Kipp, M.E. [Sandia National Labs., Albuquerque, NM (United States)

    1998-03-01

    In the present study we describe the development of an experimental fracture material property test method specific to dynamic fragmentation. Spherical test samples of the metals of interest are subjected to controlled impulsive stress loads by acceleration to high velocities with a light-gas launcher facility and subsequent normal impact on thin plates. Motion, deformation and fragmentation of the test samples are diagnosed with multiple flash radiography methods. The impact plate materials are selected to be transparent to the x-ray method so that only test metal material is imaged. Through a systematic series of such tests both strain-to-failure and fragmentation resistance properties are determined through this experimental method. Fragmentation property data for several steels, copper, aluminum, tantalum and titanium have been obtained to date. Aspects of the dynamic data have been analyzed with computational methods to achieve a better understanding of the processes leading to failure and fragmentation, and to test an existing computational fragmentation model.

  13. 77 FR 14022 - Guidance for Industry on Chemistry, Manufacturing, and Controls Information-Fermentation-Derived...

    Science.gov (United States)

    2012-03-08

    ...] Guidance for Industry on Chemistry, Manufacturing, and Controls Information--Fermentation-Derived... (CMC) Information-- Fermentation-Derived Intermediates, Drug Substances, and Related Drug Products for... to submit to support the CMC information for fermentation-derived intermediates, drug substances, and...

  14. EPRI BWR Water Chemistry Guidelines Revision

    International Nuclear Information System (INIS)

    Garcia, Susan E.; Giannelli, Joseph F.

    2014-01-01

    BWRVIP-190: BWR Water Chemistry Guidelines – 2008 Revision has been revised. The revision committee consisted of U.S. and non-U.S. utilities (members of the BWR Vessel and Internals Protection (BWRVIP) Mitigation Committee), reactor system manufacturers, fuel suppliers, and EPRI and industry experts. The revised document, BWRVIP-190 Revision 1, was completely reformatted into two volumes, with a simplified presentation of water chemistry control, diagnostic and good practice parameters in Volume 1 and the technical bases in Volume 2, to facilitate use. The revision was developed in parallel and in coordination with preparation of the Fuel Reliability Guidelines Revision 1: BWR Fuel Cladding Crud and Corrosion. Guidance is included for plants operating under normal water chemistry (NWC), moderate hydrogen water chemistry (HWC-M), and noble metal application (GE-Hitachi NobleChem™) plus hydrogen injection. Volume 1 includes significant changes to BWR feedwater and reactor water chemistry control parameters to provide increased assurance of intergranular stress corrosion cracking (IGSCC) mitigation of reactor materials and fuel reliability during all plant conditions, including cold shutdown (≤200°F (93°C)), startup/hot standby (>200°F (93°C) and ≤ 10%) and power operation (>10% power). Action Level values for chloride and sulfate have been tightened to minimize environmentally assisted cracking (EAC) of all wetted surfaces, including those not protected by hydrogen injection, with or without noble metals. Chemistry control guidance has been enhanced to minimize shutdown radiation fields by clarifying targets for depleted zinc oxide (DZO) injection while meeting requirements for fuel reliability. Improved tabular presentations of parameter values explicitly indicate levels at which actions are to be taken and required sampling frequencies. Volume 2 provides the technical bases for BWR water chemistry control for control of EAC, flow accelerated corrosion

  15. Quantitative experimental modelling of fragmentation during explosive volcanism

    Science.gov (United States)

    Thordén Haug, Ø.; Galland, O.; Gisler, G.

    2012-04-01

    Phreatomagmatic eruptions results from the violent interaction between magma and an external source of water, such as ground water or a lake. This interaction causes fragmentation of the magma and/or the host rock, resulting in coarse-grained (lapilli) to very fine-grained (ash) material. The products of phreatomagmatic explosions are classically described by their fragment size distribution, which commonly follows power laws of exponent D. Such descriptive approach, however, considers the final products only and do not provide information on the dynamics of fragmentation. The aim of this contribution is thus to address the following fundamental questions. What are the physics that govern fragmentation processes? How fragmentation occurs through time? What are the mechanisms that produce power law fragment size distributions? And what are the scaling laws that control the exponent D? To address these questions, we performed a quantitative experimental study. The setup consists of a Hele-Shaw cell filled with a layer of cohesive silica flour, at the base of which a pulse of pressurized air is injected, leading to fragmentation of the layer of flour. The fragmentation process is monitored through time using a high-speed camera. By varying systematically the air pressure (P) and the thickness of the flour layer (h) we observed two morphologies of fragmentation: "lift off" where the silica flour above the injection inlet is ejected upwards, and "channeling" where the air pierces through the layer along sub-vertical conduit. By building a phase diagram, we show that the morphology is controlled by P/dgh, where d is the density of the flour and g is the gravitational acceleration. To quantify the fragmentation process, we developed a Matlab image analysis program, which calculates the number and sizes of the fragments, and so the fragment size distribution, during the experiments. The fragment size distributions are in general described by power law distributions of

  16. Water chemistry regimes for VVER-440 units: water chemistry influence on fuel cladding behaviour

    International Nuclear Information System (INIS)

    Zmitko, M.

    1999-01-01

    In this lecture next problems of water chemistry influence on fuel cladding behaviour for VVER-440 units are presented: primary coolant technologies; water chemistry specification and control; fuel integrity considerations; zirconium alloys cladding corrosion (corrosion versus burn-up; water chemistry effect; crud deposition; hydrogen absorption; axial offset anomaly); alternatives for the primary coolant regimes

  17. Fragmentation of massive dense cores down to ≲ 1000 AU: Relation between fragmentation and density structure

    International Nuclear Information System (INIS)

    Palau, Aina; Girart, Josep M.; Estalella, Robert; Fuente, Asunción; Fontani, Francesco; Sánchez-Monge, Álvaro; Commerçon, Benoit; Hennebelle, Patrick; Busquet, Gemma; Bontemps, Sylvain; Zapata, Luis A.; Zhang, Qizhou; Di Francesco, James

    2014-01-01

    In order to shed light on the main physical processes controlling fragmentation of massive dense cores, we present a uniform study of the density structure of 19 massive dense cores, selected to be at similar evolutionary stages, for which their relative fragmentation level was assessed in a previous work. We inferred the density structure of the 19 cores through a simultaneous fit of the radial intensity profiles at 450 and 850 μm (or 1.2 mm in two cases) and the spectral energy distribution, assuming spherical symmetry and that the density and temperature of the cores decrease with radius following power-laws. Even though the estimated fragmentation level is strictly speaking a lower limit, its relative value is significant and several trends could be explored with our data. We find a weak (inverse) trend of fragmentation level and density power-law index, with steeper density profiles tending to show lower fragmentation, and vice versa. In addition, we find a trend of fragmentation increasing with density within a given radius, which arises from a combination of flat density profile and high central density and is consistent with Jeans fragmentation. We considered the effects of rotational-to-gravitational energy ratio, non-thermal velocity dispersion, and turbulence mode on the density structure of the cores, and found that compressive turbulence seems to yield higher central densities. Finally, a possible explanation for the origin of cores with concentrated density profiles, which are the cores showing no fragmentation, could be related with a strong magnetic field, consistent with the outcome of radiation magnetohydrodynamic simulations.

  18. Fragmentation of massive dense cores down to ≲ 1000 AU: Relation between fragmentation and density structure

    Energy Technology Data Exchange (ETDEWEB)

    Palau, Aina; Girart, Josep M. [Institut de Ciències de l' Espai (CSIC-IEEC), Campus UAB-Facultat de Ciències, Torre C5-parell 2, E-08193 Bellaterra, Catalunya (Spain); Estalella, Robert [Departament d' Astronomia i Meteorologia (IEEC-UB), Institut de Ciències del Cosmos, Universitat de Barcelona, Martí i Franquès, 1, E-08028 Barcelona (Spain); Fuente, Asunción [Observatorio Astronómico Nacional, P.O. Box 112, E-28803 Alcalá de Henares, Madrid (Spain); Fontani, Francesco; Sánchez-Monge, Álvaro [Osservatorio Astrofisico di Arcetri, INAF, Lago E. Fermi 5, I-50125 Firenze (Italy); Commerçon, Benoit; Hennebelle, Patrick [Laboratoire de Radioastronomie, UMR CNRS 8112, École Normale Supérieure et Observatoire de Paris, 24 rue Lhomond, F-75231 Paris Cedex 05 (France); Busquet, Gemma [INAF-Istituto di Astrofisica e Planetologia Spaziali, Area di Recerca di Tor Vergata, Via Fosso Cavaliere 100, I-00133 Roma (Italy); Bontemps, Sylvain [Université de Bordeaux, LAB, UMR 5804, F-33270 Floirac (France); Zapata, Luis A. [Centro de Radioastronomía y Astrofísica, Universidad Nacional Autónoma de México, P.O. Box 3-72, 58090 Morelia, Michoacán (Mexico); Zhang, Qizhou [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Di Francesco, James, E-mail: palau@ieec.uab.es [Department of Physics and Astronomy, University of Victoria, P.O. Box 355, STN CSC, Victoria, BC, V8W 3P6 (Canada)

    2014-04-10

    In order to shed light on the main physical processes controlling fragmentation of massive dense cores, we present a uniform study of the density structure of 19 massive dense cores, selected to be at similar evolutionary stages, for which their relative fragmentation level was assessed in a previous work. We inferred the density structure of the 19 cores through a simultaneous fit of the radial intensity profiles at 450 and 850 μm (or 1.2 mm in two cases) and the spectral energy distribution, assuming spherical symmetry and that the density and temperature of the cores decrease with radius following power-laws. Even though the estimated fragmentation level is strictly speaking a lower limit, its relative value is significant and several trends could be explored with our data. We find a weak (inverse) trend of fragmentation level and density power-law index, with steeper density profiles tending to show lower fragmentation, and vice versa. In addition, we find a trend of fragmentation increasing with density within a given radius, which arises from a combination of flat density profile and high central density and is consistent with Jeans fragmentation. We considered the effects of rotational-to-gravitational energy ratio, non-thermal velocity dispersion, and turbulence mode on the density structure of the cores, and found that compressive turbulence seems to yield higher central densities. Finally, a possible explanation for the origin of cores with concentrated density profiles, which are the cores showing no fragmentation, could be related with a strong magnetic field, consistent with the outcome of radiation magnetohydrodynamic simulations.

  19. Biodegradable hyaluronic acid hydrogels to control release of dexamethasone through aqueous Diels–Alder chemistry for adipose tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Ming; Ma, Ye; Zhang, Ziwei; Mao, Jiahui [School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing (China); Tan, Huaping, E-mail: hptan@njust.edu.cn [School of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing (China); Hu, Xiaohong [School of Material Engineering, Jinling Institute of Technology, Nanjing (China)

    2015-11-01

    A robust synthetic strategy of biopolymer-based hydrogels has been developed where hyaluronic acid derivatives reacted through aqueous Diels–Alder chemistry without the involvement of chemical catalysts, allowing for control and sustain release of dexamethasone. To conjugate the hydrogel, furan and maleimide functionalized hyaluronic acid were synthesized, respectively, as well as furan functionalized dexamethasone, for the covalent immobilization. Chemical structure, gelation time, morphologies, swelling kinetics, weight loss, compressive modulus and dexamethasone release of the hydrogel system in PBS at 37 °C were studied. The results demonstrated that the aqueous Diels–Alder chemistry provides an extremely selective reaction and proceeds with high efficiency for hydrogel conjugation and covalent immobilization of dexamethasone. Cell culture results showed that the dexamethasone immobilized hydrogel was noncytotoxic and preserved proliferation of entrapped human adipose-derived stem cells. This synthetic approach uniquely allows for the direct fabrication of biologically functionalized gel scaffolds with ideal structures for adipose tissue engineering, which provides a competitive alternative to conventional conjugation techniques such as copper mediated click chemistry. - Highlights: • A biodegradable hyaluronic acid hydrogel was crosslinked via aqueous Diels–Alder chemistry. • Dexamethasone was covalently immobilized into the hyaluronic acid hydrogel via aqueous Diels–Alder chemistry. • Dexamethasone could be released from the Diels–Alder hyaluronic acid hydrogel in a controlled fashion.

  20. Biodegradable hyaluronic acid hydrogels to control release of dexamethasone through aqueous Diels–Alder chemistry for adipose tissue engineering

    International Nuclear Information System (INIS)

    Fan, Ming; Ma, Ye; Zhang, Ziwei; Mao, Jiahui; Tan, Huaping; Hu, Xiaohong

    2015-01-01

    A robust synthetic strategy of biopolymer-based hydrogels has been developed where hyaluronic acid derivatives reacted through aqueous Diels–Alder chemistry without the involvement of chemical catalysts, allowing for control and sustain release of dexamethasone. To conjugate the hydrogel, furan and maleimide functionalized hyaluronic acid were synthesized, respectively, as well as furan functionalized dexamethasone, for the covalent immobilization. Chemical structure, gelation time, morphologies, swelling kinetics, weight loss, compressive modulus and dexamethasone release of the hydrogel system in PBS at 37 °C were studied. The results demonstrated that the aqueous Diels–Alder chemistry provides an extremely selective reaction and proceeds with high efficiency for hydrogel conjugation and covalent immobilization of dexamethasone. Cell culture results showed that the dexamethasone immobilized hydrogel was noncytotoxic and preserved proliferation of entrapped human adipose-derived stem cells. This synthetic approach uniquely allows for the direct fabrication of biologically functionalized gel scaffolds with ideal structures for adipose tissue engineering, which provides a competitive alternative to conventional conjugation techniques such as copper mediated click chemistry. - Highlights: • A biodegradable hyaluronic acid hydrogel was crosslinked via aqueous Diels–Alder chemistry. • Dexamethasone was covalently immobilized into the hyaluronic acid hydrogel via aqueous Diels–Alder chemistry. • Dexamethasone could be released from the Diels–Alder hyaluronic acid hydrogel in a controlled fashion

  1. Chemistry and radiochemistry strategies supported by FA3-EPRTM and UK-EPRTM auxiliary systems: performances and control

    International Nuclear Information System (INIS)

    Tigeras, Arancha; Fourment, Pierre; Elgallaf; Anas; Chupin, Antoine; Fauvel, Nicola

    2012-09-01

    The design and the operation of auxiliary systems play an essential role in: - the preservation of the primary circuit integrity, - the prevention of hydrogen risk, - the control of the boron concentration and radioactivity, - the application of pH and zinc programmes. While the source term generation mainly depends on the primary circuit material and primary coolant chemistry conditioning, the source term spreading is directly linked to the auxiliary systems treatment and performances. Indeed, the auxiliary systems regulate the boron, hydrogen, lithium and zinc injection as well as the countermeasures to ensure the reactivity control and the hazardous H 2 /O 2 mixture prevention. The main principles governing the chemistry and radiochemistry in the auxiliary systems are based on the application of: - Design features for hydrogen and boron management. - Criteria for selecting the appropriate material of each system considering the functional requirements and the source term build up reduction. - Measures for minimizing the activity deposition on the surfaces of components and pipings. - Adequate and reliable systems of purification for reducing the accumulation of liquid/gas radioactivity and impurities in the circuits and for optimizing the waste production. - Chemistry program for limiting the material corrosion of auxiliary systems and preventing the source term transfer to the core. - Appropriate sampling locations and equipment to monitor the chemistry and radiochemistry parameters. This paper describes the operation of the main auxiliary systems of FLAMANVILLE3-EPR TM and UK-EPR- TM participating in the chemistry/radiochemistry management such as Chemical and Volume Control System (CVCS), Reactor Borated Water Make-up System (RBWMS), Coolant Treatment System (CTS), Gaseous Waste Processing System (GWPS), Fuel Pool Purification System (PTR [FPPS/FPCS]) also. The performances requested to these systems and the chemistry programs applied to them are discussed

  2. Role of photoexcited nitrogen dioxide chemistry on ozone formation and emission control strategy over the Pearl River Delta, China

    Science.gov (United States)

    A new hydroxyl radical formation pathway via photo-excited nitrogen dioxide chemistry is incorporated into a chemistry-only box model as well as a 3D air quality model to examine its potential role on ozone formation and emission control strategy over the Pearl River Delta region...

  3. Fragment-based approaches to anti-HIV drug discovery: state of the art and future opportunities.

    Science.gov (United States)

    Huang, Boshi; Kang, Dongwei; Zhan, Peng; Liu, Xinyong

    2015-12-01

    The search for additional drugs to treat HIV infection is a continuing effort due to the emergence and spread of HIV strains resistant to nearly all current drugs. The recent literature reveals that fragment-based drug design/discovery (FBDD) has become an effective alternative to conventional high-throughput screening strategies for drug discovery. In this critical review, the authors describe the state of the art in FBDD strategies for the discovery of anti-HIV drug-like compounds. The article focuses on fragment screening techniques, direct fragment-based design and early hit-to-lead progress. Rapid progress in biophysical detection and in silico techniques has greatly aided the application of FBDD to discover candidate agents directed at a variety of anti-HIV targets. Growing evidence suggests that structural insights on key proteins in the HIV life cycle can be applied in the early phase of drug discovery campaigns, providing valuable information on the binding modes and efficiently prompting fragment hit-to-lead progression. The combination of structural insights with improved methodologies for FBDD, including the privileged fragment-based reconstruction approach, fragment hybridization based on crystallographic overlays, fragment growth exploiting dynamic combinatorial chemistry, and high-speed fragment assembly via diversity-oriented synthesis followed by in situ screening, offers the possibility of more efficient and rapid discovery of novel drugs for HIV-1 prevention or treatment. Though the use of FBDD in anti-HIV drug discovery is still in its infancy, it is anticipated that anti-HIV agents developed via fragment-based strategies will be introduced into the clinic in the future.

  4. Aerosol Fragmentation Driven by Coupling of Acid-Base and Free-Radical Chemistry in the Heterogeneous Oxidation of Aqueous Citric Acid by OH Radicals.

    Science.gov (United States)

    Liu, Matthew J; Wiegel, Aaron A; Wilson, Kevin R; Houle, Frances A

    2017-08-10

    A key uncertainty in the heterogeneous oxidation of carboxylic acids by hydroxyl radicals (OH) in aqueous-phase aerosol is how the free-radical reaction pathways might be altered by acid-base chemistry. In particular, if acid-base reactions occur concurrently with acyloxy radical formation and unimolecular decomposition of alkoxy radicals, there is a possibility that differences in reaction pathways impact the partitioning of organic carbon between the gas and aqueous phases. To examine these questions, a kinetic model is developed for the OH-initiated oxidation of citric acid aerosol at high relative humidity. The reaction scheme, containing both free-radical and acid-base elementary reaction steps with physically validated rate coefficients, accurately predicts the experimentally observed molecular composition, particle size, and average elemental composition of the aerosol upon oxidation. The difference between the two reaction channels centers on the reactivity of carboxylic acid groups. Free-radical reactions mainly add functional groups to the carbon skeleton of neutral citric acid, because carboxylic acid moieties deactivate the unimolecular fragmentation of alkoxy radicals. In contrast, the conjugate carboxylate groups originating from acid-base equilibria activate both acyloxy radical formation and carbon-carbon bond scission of alkoxy radicals, leading to the formation of low molecular weight, highly oxidized products such as oxalic and mesoxalic acid. Subsequent hydration of carbonyl groups in the oxidized products increases the aerosol hygroscopicity and accelerates the substantial water uptake and volume growth that accompany oxidation. These results frame the oxidative lifecycle of atmospheric aerosol: it is governed by feedbacks between reactions that first increase the particle oxidation state, then eventually promote water uptake and acid-base chemistry. When coupled to free-radical reactions, acid-base channels lead to formation of low molecular

  5. SNS Resonance Control Cooling Systems and Quadrupole Magnet Cooling Systems DIW Chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Magda, Karoly [ORNL

    2018-01-01

    This report focuses on control of the water chemistry for the Spallation Neutron Source (SNS) Resonance Control Cooling System (RCCS)/Quadrupole Magnet Cooling System (QMCS) deionized water (DIW) cooling loops. Data collected from spring 2013 through spring 2016 are discussed, and an operations regime is recommended.It was found that the RCCS operates with an average pH of 7.24 for all lines (from 7.0 to 7.5, slightly alkaline), the average low dissolved oxygen is in the area of < 36 ppb, and the main loop average resistivity of is > 14 MΩ-cm. The QMCS was found to be operating in a similar regime, with a slightly alkaline pH of 7.5 , low dissolved oxygen in the area of < 45 ppb, and main loop resistivity of 10 to 15 MΩ-cm. During data reading, operational corrections were done on the polishing loops to improve the water chemistry regime. Therefore some trends changed over time.It is recommended that the cooling loops operate in a regime in which the water has a resistivity that is as high as achievable, a dissolved oxygen concentration that is as low as achievable, and a neutral or slightly alkaline pH.

  6. Analytical chemistry in semiconductor manufacturing: Techniques, role of nuclear methods and need for quality control

    International Nuclear Information System (INIS)

    1989-06-01

    This report is the result of a consultants meeting held in Gaithersburg, USA, 2-3 October 1987. The meeting was hosted by the National Bureau of Standards and Technology, and it was attended by 18 participants from Denmark, Finland, India, Japan, Norway, People's Republic of China and the USA. The purpose of the meeting was to assess the present status of analytical chemistry in semiconductor manufacturing, the role of nuclear analytical methods and the need for internationally organized quality control of the chemical analysis. The report contains the three presentations in full and a summary report of the discussions. Thus, it gives an overview of the need of analytical chemistry in manufacturing of silicon based devices, the use of nuclear analytical methods, and discusses the need for quality control. Refs, figs and tabs

  7. Data processing technologies and diagnostics for water chemistry and corrosion control in nuclear power plants (DAWAC). Report of a coordinated research project 2001-2005

    International Nuclear Information System (INIS)

    2006-06-01

    This publication provides information on the current status and development trends in monitoring, diagnostics and control of water chemistry and corrosion of core and primary circuit materials in water cooled power reactors. It summarizes the results of an IAEA Coordinated Research Project and focuses on the methods for development, qualification and implementation of water chemistry expert systems at nuclear power plants. These systems are needed to have full benefit from using on-line sensors in real time mode when sensor signals, and other chemistry and operational data, are collected and continuously analysed with data acquisition and evaluation software. Technical knowledge was acquired in water chemistry control techniques (grab sampling, on-line monitoring, data collecting and processing, etc), plant chemistry and corrosion diagnostics, plant monitoring (corrosion, chemistry, activity) and plant chemistry improvement (analytical models and practices). This publication covers contributions from leading experts in water chemistry/corrosion, representing organizations from 16 countries with the largest nuclear capacities

  8. Complex Protostellar Chemistry

    Science.gov (United States)

    Nuth, Joseph A., III; Johnson, Natasha M.

    2012-01-01

    Two decades ago, our understanding of the chemistry in protostars was simple-matter either fell into the central star or was trapped in planetary-scale objects. Some minor chemical changes might occur as the dust and gas fell inward, but such effects were overwhelmed by the much larger scale processes that occurred even in bodies as small as asteroids. The chemistry that did occur in the nebula was relatively easy to model because the fall from the cold molecular cloud into the growing star was a one-way trip down a well-known temperature-pressure gradient; the only free variable was time. However, just over 10 years ago it was suggested that some material could be processed in the inner nebula, flow outward, and become incorporated into comets (1, 2). This outward flow was confirmed when the Stardust mission returned crystalline mineral fragments (3) from Comet Wild 2 that must have been processed close to the Sun before they were incorporated into the comet. In this week's Science Express, Ciesla and Sandford (4) demonstrate that even the outermost regions of the solar nebula can be a chemically active environment. Their finding could have consequences for the rest of the nebula.

  9. Treatment of sleep apnea in chronic heart failure patients with auto-servo ventilation improves sleep fragmentation: a randomized controlled trial.

    Science.gov (United States)

    Hetzenecker, Andrea; Escourrou, Pierre; Kuna, Samuel T; Series, Frederic; Lewis, Keir; Birner, Christoph; Pfeifer, Michael; Arzt, Michael

    2016-01-01

    Impaired sleep efficiency is independently associated with worse prognosis in patients with chronic heart failure (CHF). Therefore, a test was conducted on whether auto-servo ventilation (ASV, biphasic positive airway pressure [BiPAP]-ASV, Philips Respironics) reduces sleep fragmentation and improves sleep efficiency in CHF patients with central sleep apnea (CSA) or obstructive sleep apnea (OSA). In this multicenter, randomized, parallel group trial, a study was conducted on 63 CHF patients (age 64 ± 10 years; left ventricular ejection fraction 29 ± 7%) with CSA or OSA (apnea-hypopnea Index, AHI 47 ± 18/h; 46% CSA) referred to sleep laboratories of the four participating centers. Participants were randomized to either ASV (n = 32) or optimal medical treatment alone (control, n = 31). Polysomnography (PSG) and actigraphy at home (home) with centralized blinded scoring were obtained at baseline and 12 weeks. ASV significantly reduced sleep fragmentation (total arousal indexPSG: -16.4 ± 20.6 vs. -0.6 ± 13.2/h, p = 0.001; sleep fragmentation indexhome: -7.6 ± 15.6 versus 4.3 ± 13.9/h, p = 0.003, respectively) and significantly increased sleep efficiency assessed by actigraphy (SEhome) compared to controls (2.3 ± 10.1 vs. -2.1 ± 6.9%, p = 0.002). Effects of ASV on sleep fragmentation and efficiency were similar in patients suffering from OSA and CSA. At home, ASV treatment modestly improves sleep fragmentation as well as sleep efficiency in CHF patients having either CSA or OSA. Copyright © 2015 Elsevier B.V. All rights reserved.

  10. PWR secondary water chemistry guidelines: Revision 3

    International Nuclear Information System (INIS)

    Lurie, S.; Bucci, G.; Johnson, L.; King, M.; Lamanna, L.; Morgan, E.; Bates, J.; Burns, R.; Eaker, R.; Ward, G.; Linnenbom, V.; Millet, P.; Paine, J.P.; Wood, C.J.; Gatten, T.; Meatheany, D.; Seager, J.; Thompson, R.; Brobst, G.; Connor, W.; Lewis, G.; Shirmer, R.; Gillen, J.; Kerns, M.; Jones, V.; Lappegaard, S.; Sawochka, S.; Smith, F.; Spires, D.; Pagan, S.; Gardner, J.; Polidoroff, T.; Lambert, S.; Dahl, B.; Hundley, F.; Miller, B.; Andersson, P.; Briden, D.; Fellers, B.; Harvey, S.; Polchow, J.; Rootham, M.; Fredrichs, T.; Flint, W.

    1993-05-01

    An effective, state-of-the art secondary water chemistry control program is essential to maximize the availability and operating life of major PWR components. Furthermore, the costs related to maintaining secondary water chemistry will likely be less than the repair or replacement of steam generators or large turbine rotors, with resulting outages taken into account. The revised PWR secondary water chemistry guidelines in this report represent the latest field and laboratory data on steam generator corrosion phenomena. This document supersedes Interim PWR Secondary Water Chemistry Recommendations for IGA/SCC Control (EPRI report TR-101230) as well as PWR Secondary Water Chemistry Guidelines--Revision 2 (NP-6239)

  11. Water chemistry guidance in nuclear power plants in Japan

    International Nuclear Information System (INIS)

    Uchida, Shunsuke; Okada, Hidetoshi; Suzuki, Hiroaki; Naitoh, Masanori

    2012-01-01

    Water chemistry plays important roles in safe and reliable plant operation which are very critical for future power rate increases as well as aging plant management. Water chemistry control is required to satisfy the need for improved integrity of target materials, and at the same time it must be optimal for all materials and systems in a plant. Optimal water chemistry can be maintained by expert engineers who are knowledgeable about plant water chemistry, who have sufficient experience with plant operation, and whose knowledge is based on fundamental technologies. One of the latest subjects in the field of water chemistry is achieving suitable technical transfers, in which the achievements and experience with plant water chemistry accumulated by experts are successfully transferred to the next generation of engineers. For this purpose, documents on experience with water chemistry are being compiled as the guidance for water chemistry control and water chemistry standards, e.g., standards for chemical analysis procedures and guidance for water chemistry control procedures. This paper introduces the latest activities in Japan in establishing water chemistry guidance involving water chemistry standards, guidance documents and their supporting documents. (orig.)

  12. Condensate and feedwater systems, pumps, and water chemistry. Volume seven

    International Nuclear Information System (INIS)

    Anon.

    1986-01-01

    Subject matter includes condensate and feedwater systems (general features of condensate and feedwater systems, condenser hotwell level control, condensate flow, feedwater flow), pumps (principles of fluid flow, types of pumps, centrifugal pumps, positive displacement pumps, jet pumps, pump operating characteristics) and water chemistry (water chemistry fundamentals, corrosion, scaling, radiochemistry, water chemistry control processes, water pretreatment, PWR water chemistry, BWR water chemistry, condenser circulating water chemistry

  13. Role of Precursor-Conversion Chemistry in the Crystal-Phase Control of Catalytically Grown Colloidal Semiconductor Quantum Wires.

    Science.gov (United States)

    Wang, Fudong; Buhro, William E

    2017-12-26

    Crystal-phase control is one of the most challenging problems in nanowire growth. We demonstrate that, in the solution-phase catalyzed growth of colloidal cadmium telluride (CdTe) quantum wires (QWs), the crystal phase can be controlled by manipulating the reaction chemistry of the Cd precursors and tri-n-octylphosphine telluride (TOPTe) to favor the production of either a CdTe solute or Te, which consequently determines the composition and (liquid or solid) state of the Bi x Cd y Te z catalyst nanoparticles. Growth of single-phase (e.g., wurtzite) QWs is achieved only from solid catalysts (y ≪ z) that enable the solution-solid-solid growth of the QWs, whereas the liquid catalysts (y ≈ z) fulfill the solution-liquid-solid growth of the polytypic QWs. Factors that affect the precursor-conversion chemistry are systematically accounted for, which are correlated with a kinetic study of the composition and state of the catalyst nanoparticles to understand the mechanism. This work reveals the role of the precursor-reaction chemistry in the crystal-phase control of catalytically grown colloidal QWs, opening the possibility of growing phase-pure QWs of other compositions.

  14. Surface chemistry: Key to control and advance myriad technologies

    Science.gov (United States)

    Yates, John T.; Campbell, Charles T.

    2011-01-01

    This special issue on surface chemistry is introduced with a brief history of the field, a summary of the importance of surface chemistry in technological applications, a brief overview of some of the most important recent developments in this field, and a look forward to some of its most exciting future directions. This collection of invited articles is intended to provide a snapshot of current developments in the field, exemplify the state of the art in fundamental research in surface chemistry, and highlight some possibilities in the future. Here, we show how those articles fit together in the bigger picture of this field. PMID:21245359

  15. Experimental modelling of fragmentation applied to volcanic explosions

    Science.gov (United States)

    Haug, Øystein Thordén; Galland, Olivier; Gisler, Galen R.

    2013-12-01

    Explosions during volcanic eruptions cause fragmentation of magma and host rock, resulting in fragments with sizes ranging from boulders to fine ash. The products can be described by fragment size distributions (FSD), which commonly follow power laws with exponent D. The processes that lead to power-law distributions and the physical parameters that control D remain unknown. We developed a quantitative experimental procedure to study the physics of the fragmentation process through time. The apparatus consists of a Hele-Shaw cell containing a layer of cohesive silica flour that is fragmented by a rapid injection of pressurized air. The evolving fragmentation of the flour is monitored with a high-speed camera, and the images are analysed to obtain the evolution of the number of fragments (N), their average size (A), and the FSD. Using the results from our image-analysis procedure, we find transient empirical laws for N, A and the exponent D of the power-law FSD as functions of the initial air pressure. We show that our experimental procedure is a promising tool for unravelling the complex physics of fragmentation during phreatomagmatic and phreatic eruptions.

  16. Fragment-based drug discovery and protein–protein interactions

    Directory of Open Access Journals (Sweden)

    Turnbull AP

    2014-09-01

    Full Text Available Andrew P Turnbull,1 Susan M Boyd,2 Björn Walse31CRT Discovery Laboratories, Department of Biological Sciences, Birkbeck, University of London, London, UK; 2IOTA Pharmaceuticals Ltd, Cambridge, UK; 3SARomics Biostructures AB, Lund, SwedenAbstract: Protein–protein interactions (PPIs are involved in many biological processes, with an estimated 400,000 PPIs within the human proteome. There is significant interest in exploiting the relatively unexplored potential of these interactions in drug discovery, driven by the need to find new therapeutic targets. Compared with classical drug discovery against targets with well-defined binding sites, developing small-molecule inhibitors against PPIs where the contact surfaces are frequently more extensive and comparatively flat, with most of the binding energy localized in “hot spots”, has proven far more challenging. However, despite the difficulties associated with targeting PPIs, important progress has been made in recent years with fragment-based drug discovery playing a pivotal role in improving their tractability. Computational and empirical approaches can be used to identify hot-spot regions and assess the druggability and ligandability of new targets, whilst fragment screening campaigns can detect low-affinity fragments that either directly or indirectly perturb the PPI. Once fragment hits have been identified and confirmed using biochemical and biophysical approaches, three-dimensional structural data derived from nuclear magnetic resonance or X-ray crystallography can be used to drive medicinal chemistry efforts towards the development of more potent inhibitors. A small-scale comparison presented in this review of “standard” fragments with those targeting PPIs has revealed that the latter tend to be larger, be more lipophilic, and contain more polar (acid/base functionality, whereas three-dimensional descriptor data indicate that there is little difference in their three

  17. Jet fragmentation

    International Nuclear Information System (INIS)

    Saxon, D.H.

    1985-10-01

    The paper reviews studies on jet fragmentation. The subject is discussed under the topic headings: fragmentation models, charged particle multiplicity, bose-einstein correlations, identified hadrons in jets, heavy quark fragmentation, baryon production, gluon and quark jets compared, the string effect, and two successful models. (U.K.)

  18. From nanofabrication to self-fabrication--tailored chemistry for control of single molecule electronic devices

    DEFF Research Database (Denmark)

    Moth-Poulsen, Kasper; Bjørnholm, Thomas

    2010-01-01

    as alternatives to the dominant top-down nanofabrication techniques. One example is solution-based self-assembly of a molecule enclosed by two gold nanorod electrodes. This article will discuss recent attempts to control the self-assembly process by the use of supramolecular chemistry and how to tailor...

  19. Missing Fragments: Detecting Cooperative Binding in Fragment-Based Drug Design

    Science.gov (United States)

    2012-01-01

    The aim of fragment-based drug design (FBDD) is to identify molecular fragments that bind to alternate subsites within a given binding pocket leading to cooperative binding when linked. In this study, the binding of fragments to human phenylethanolamine N-methyltransferase is used to illustrate how (a) current protocols may fail to detect fragments that bind cooperatively, (b) theoretical approaches can be used to validate potential hits, and (c) apparent false positives obtained when screening against cocktails of fragments may in fact indicate promising leads. PMID:24900472

  20. Network analysis reveals multiscale controls on streamwater chemistry

    Science.gov (United States)

    McGuire, Kevin J.; Torgersen, Christian E.; Likens, Gene E.; Buso, Donald C.; Lowe, Winsor H.; Bailey, Scott W.

    2014-01-01

    By coupling synoptic data from a basin-wide assessment of streamwater chemistry with network-based geostatistical analysis, we show that spatial processes differentially affect biogeochemical condition and pattern across a headwater stream network. We analyzed a high-resolution dataset consisting of 664 water samples collected every 100 m throughout 32 tributaries in an entire fifth-order stream network. These samples were analyzed for an exhaustive suite of chemical constituents. The fine grain and broad extent of this study design allowed us to quantify spatial patterns over a range of scales by using empirical semivariograms that explicitly incorporated network topology. Here, we show that spatial structure, as determined by the characteristic shape of the semivariograms, differed both among chemical constituents and by spatial relationship (flow-connected, flow-unconnected, or Euclidean). Spatial structure was apparent at either a single scale or at multiple nested scales, suggesting separate processes operating simultaneously within the stream network and surrounding terrestrial landscape. Expected patterns of spatial dependence for flow-connected relationships (e.g., increasing homogeneity with downstream distance) occurred for some chemical constituents (e.g., dissolved organic carbon, sulfate, and aluminum) but not for others (e.g., nitrate, sodium). By comparing semivariograms for the different chemical constituents and spatial relationships, we were able to separate effects on streamwater chemistry of (i) fine-scale versus broad-scale processes and (ii) in-stream processes versus landscape controls. These findings provide insight on the hierarchical scaling of local, longitudinal, and landscape processes that drive biogeochemical patterns in stream networks.

  1. Network analysis reveals multiscale controls on streamwater chemistry.

    Science.gov (United States)

    McGuire, Kevin J; Torgersen, Christian E; Likens, Gene E; Buso, Donald C; Lowe, Winsor H; Bailey, Scott W

    2014-05-13

    By coupling synoptic data from a basin-wide assessment of streamwater chemistry with network-based geostatistical analysis, we show that spatial processes differentially affect biogeochemical condition and pattern across a headwater stream network. We analyzed a high-resolution dataset consisting of 664 water samples collected every 100 m throughout 32 tributaries in an entire fifth-order stream network. These samples were analyzed for an exhaustive suite of chemical constituents. The fine grain and broad extent of this study design allowed us to quantify spatial patterns over a range of scales by using empirical semivariograms that explicitly incorporated network topology. Here, we show that spatial structure, as determined by the characteristic shape of the semivariograms, differed both among chemical constituents and by spatial relationship (flow-connected, flow-unconnected, or Euclidean). Spatial structure was apparent at either a single scale or at multiple nested scales, suggesting separate processes operating simultaneously within the stream network and surrounding terrestrial landscape. Expected patterns of spatial dependence for flow-connected relationships (e.g., increasing homogeneity with downstream distance) occurred for some chemical constituents (e.g., dissolved organic carbon, sulfate, and aluminum) but not for others (e.g., nitrate, sodium). By comparing semivariograms for the different chemical constituents and spatial relationships, we were able to separate effects on streamwater chemistry of (i) fine-scale versus broad-scale processes and (ii) in-stream processes versus landscape controls. These findings provide insight on the hierarchical scaling of local, longitudinal, and landscape processes that drive biogeochemical patterns in stream networks.

  2. Chemistry in Microfluidic Channels

    Science.gov (United States)

    Chia, Matthew C.; Sweeney, Christina M.; Odom, Teri W.

    2011-01-01

    General chemistry introduces principles such as acid-base chemistry, mixing, and precipitation that are usually demonstrated in bulk solutions. In this laboratory experiment, we describe how chemical reactions can be performed in a microfluidic channel to show advanced concepts such as laminar fluid flow and controlled precipitation. Three sets of…

  3. Photodissociation of ultracold diatomic strontium molecules with quantum state control.

    Science.gov (United States)

    McDonald, M; McGuyer, B H; Apfelbeck, F; Lee, C-H; Majewska, I; Moszynski, R; Zelevinsky, T

    2016-07-07

    Chemical reactions at ultracold temperatures are expected to be dominated by quantum mechanical effects. Although progress towards ultracold chemistry has been made through atomic photoassociation, Feshbach resonances and bimolecular collisions, these approaches have been limited by imperfect quantum state selectivity. In particular, attaining complete control of the ground or excited continuum quantum states has remained a challenge. Here we achieve this control using photodissociation, an approach that encodes a wealth of information in the angular distribution of outgoing fragments. By photodissociating ultracold (88)Sr2 molecules with full control of the low-energy continuum, we access the quantum regime of ultracold chemistry, observing resonant and nonresonant barrier tunnelling, matter-wave interference of reaction products and forbidden reaction pathways. Our results illustrate the failure of the traditional quasiclassical model of photodissociation and instead are accurately described by a quantum mechanical model. The experimental ability to produce well-defined quantum continuum states at low energies will enable high-precision studies of long-range molecular potentials for which accurate quantum chemistry models are unavailable, and may serve as a source of entangled states and coherent matter waves for a wide range of experiments in quantum optics.

  4. Enhancing prospective chemistry teachers cognitive structures in the topics of bonding and hybridization by internet-assisted chemistry applications

    OpenAIRE

    Özge Özyalçın Oskay, Sinem Dinçol

    2011-01-01

    The purpose of this study is to determine the effects of internet-assisted chemistry applications on prospective chemistry teachers’ cognitive structures in the topics of bonding and hybridization. The sample of the study consisted of 36 prospective chemistry teachers attending Hacettepe University, Faculty of Education, the Department of Chemistry Education in 2010-2011 academic year and taking Basic Chemistry I lesson. In the study, students were separated into experimental and control gr...

  5. Cryobiology of coral fragments.

    Science.gov (United States)

    Hagedorn, Mary; Farrell, Ann; Carter, Virginia L

    2013-02-01

    Around the world, coral reefs are dying due to human influences, and saving habitat alone may not stop this destruction. This investigation focused on the biological processes that will provide the first steps in understanding the cryobiology of whole coral fragments. Coral fragments are a partnership of coral tissue and endosymbiotic algae, Symbiodinium sp., commonly called zooxanthellae. These data reflected their separate sensitivities to chilling and a cryoprotectant (dimethyl sulfoxide) for the coral Pocillopora damicornis, as measured by tissue loss and Pulse Amplitude Modulated fluorometry 3weeks post-treatment. Five cryoprotectant treatments maintained the viability of the coral tissue and zooxanthellae at control values (1M dimethyl sulfoxide at 1.0, 1.5 and 2.0h exposures, and 1.5M dimethyl sulfoxide at 1.0 and 1.5h exposures, P>0.05, ANOVA), whereas 2M concentrations did not (Pzooxanthellae. During the winter when the fragments were chilled, the coral tissue remained relatively intact (∼25% loss) post-treatment, but the zooxanthellae numbers in the tissue declined after 5min of chilling (Pzooxanthellae numbers declined in response to chilling alone (P0.05, ANOVA), but it did not protect against the loss of zooxanthellae (Pzooxanthellae are the most sensitive element in the coral fragment complex and future cryopreservation protocols must be guided by their greater sensitivity. Copyright © 2012 Elsevier Inc. All rights reserved.

  6. High-density metals and metallic composites for improved fragmentation submunitions

    International Nuclear Information System (INIS)

    Craig, B.G.; Honnell, R.E.; Lederman, G.F. Jr.; Sandstrom, D.J.

    1975-08-01

    The fragmentation of cases (50.8-mm-id) made of tungsten, a tungsten alloy, and depleted uranium (D-38) can be controlled, and velocities greater than 1 mm/μs can be achieved for lethal size fragment weights. Fragmentation was controlled by internal grooves, by internal screens, and by a spheroid-in-weak-matrix scheme. A thin polymer liner was used inside of a grooved tungsten case in one experiment; this system performed exceptionally well. The ease of fabricating cases with D-38 or with the tungsten-alloy spheroid-in-matrix scheme offers an attractive advantage over tungsten and tungsten alloy

  7. SPR-based fragment screening with neurotensin receptor 1 generates novel small molecule ligands

    Science.gov (United States)

    Huber, Sylwia; Casagrande, Fabio; Hug, Melanie N.; Wang, Lisha; Heine, Philipp; Kummer, Lutz; Plückthun, Andreas; Hennig, Michael

    2017-01-01

    The neurotensin receptor 1 represents an important drug target involved in various diseases of the central nervous system. So far, the full exploitation of potential therapeutic activities has been compromised by the lack of compounds with favorable physicochemical and pharmacokinetic properties which efficiently penetrate the blood-brain barrier. Recent progress in the generation of stabilized variants of solubilized neurotensin receptor 1 and its subsequent purification and successful structure determination presents a solid starting point to apply the approach of fragment-based screening to extend the chemical space of known neurotensin receptor 1 ligands. In this report, surface plasmon resonance was used as primary method to screen 6369 compounds. Thereby 44 hits were identified and confirmed in competition as well as dose-response experiments. Furthermore, 4 out of 8 selected hits were validated using nuclear magnetic resonance spectroscopy as orthogonal biophysical method. Computational analysis of the compound structures, taking the known crystal structure of the endogenous peptide agonist into consideration, gave insight into the potential fragment-binding location and interactions and inspires chemistry efforts for further exploration of the fragments. PMID:28510609

  8. Advanced chemistry management system for nuclear power plants

    International Nuclear Information System (INIS)

    Maeda, Katsuji; Kobayashi, Yasuhiro; Nagasawa, Katsumi

    2000-01-01

    Chemistry control in a boiling water reactor (BWR) plant has a close relationship with radiation field buildup, fuel reliability, integrity of plant components and materials, performance of the water treatment systems and radioactive waste generation. Chemistry management in BWR plants has become more important in order to maintain and enhance plant reliability. Adequate chemistry control and management are also essential to establish, maintain, and enhance plant availability. For these reasons, we have developed the advanced chemistry management system for nuclear power plants in order to effectively collect and evaluate a large number of plant operating and chemistry data. (author)

  9. From Protein Structure to Small-Molecules: Recent Advances and Applications to Fragment-Based Drug Discovery.

    Science.gov (United States)

    Ferreira, Leonardo G; Andricopulo, Adriano D

    2017-01-01

    Fragment-based drug discovery (FBDD) is a broadly used strategy in structure-guided ligand design, whereby low-molecular weight hits move from lead-like to drug-like compounds. Over the past 15 years, an increasingly important role of the integration of these strategies into industrial and academic research platforms has been successfully established, allowing outstanding contributions to drug discovery. One important factor for the current prominence of FBDD is the better coverage of the chemical space provided by fragment-like libraries. The development of the field relies on two features: (i) the growing number of structurally characterized drug targets and (ii) the enormous chemical diversity available for experimental and virtual screenings. Indeed, fragment-based campaigns have contributed to address major challenges in lead optimization, such as the appropriate physicochemical profile of clinical candidates. This perspective paper outlines the usefulness and applications of FBDD approaches in medicinal chemistry and drug design. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  10. Development of an automated system for CANDU secondary coolant circuit chemistry control

    International Nuclear Information System (INIS)

    Dean, J.R.; Stewart, R.B.

    1978-04-01

    This report is a summary of work done to develop a means for automated control of the secondary coolant chemistry of CANDU 600 MW(e) power reactors using on-line analyzers and a minicomputer. The development work was carried out in cooperation with Saskatchewan Power Corporation at Estevan. Results and conclusions of the program are included, as are recommendations for a prototype installation in a domestic CANDU 600 MW steam generator. (author)

  11. An overview of KANUPP operating experience in chemistry

    International Nuclear Information System (INIS)

    Hashmi, T.

    2010-01-01

    KANUPP is a small CANDU® type PHWR (137MWe), commissioned in 1972 and now operating after life extension (PLEX) since 2004. This paper contains an overview of the plant operating experience in chemistry control over the past year including life extension period. Emphasis is on: Success story; Practices; Future improvements in chemistry programs. Considerable efforts are underway to maintain plant equipment and systems to mitigate the effect of plant ageing. The improvements that have been made at the station are as under: Heat transport system (HTS) chemistry, its effects on construction material; Feed water chemistry on secondary side (considering the condenser leaks). Strict chemistry control is being exercised for the heat transport system (HTS) for its better chemistry control. For short term, the changes are limited to pH adjustments of HTS. This change decreases the rate of thinning of outlet feeders as noted in some CANDUs® due to flow accelerated corrosion (FAC). Water Treatment Plant has been refurbished to get very low total dissolved solids (TDS) de-mineralized water for secondary side systems of the plant. Experience of steam generators flushing before startup, sludge pile analyses mapping, verification of pH from different sampling points of SGs, are the short term mitigating actions to address sludge pile problem in steam generators (SGs). The R and D on HTS and SGs is multifaceted and is aimed at achieving optimum chemistry control. Study is being conducted for improving chemistry control for the material, equipment and systems of the plant. (author)

  12. Towards a population synthesis model of self-gravitating disc fragmentation and tidal downsizing II: the effect of fragment-fragment interactions

    Science.gov (United States)

    Forgan, D. H.; Hall, C.; Meru, F.; Rice, W. K. M.

    2018-03-01

    It is likely that most protostellar systems undergo a brief phase where the protostellar disc is self-gravitating. If these discs are prone to fragmentation, then they are able to rapidly form objects that are initially of several Jupiter masses and larger. The fate of these disc fragments (and the fate of planetary bodies formed afterwards via core accretion) depends sensitively not only on the fragment's interaction with the disc, but also with its neighbouring fragments. We return to and revise our population synthesis model of self-gravitating disc fragmentation and tidal downsizing. Amongst other improvements, the model now directly incorporates fragment-fragment interactions while the disc is still present. We find that fragment-fragment scattering dominates the orbital evolution, even when we enforce rapid migration and inefficient gap formation. Compared to our previous model, we see a small increase in the number of terrestrial-type objects being formed, although their survival under tidal evolution is at best unclear. We also see evidence for disrupted fragments with evolved grain populations - this is circumstantial evidence for the formation of planetesimal belts, a phenomenon not seen in runs where fragment-fragment interactions are ignored. In spite of intense dynamical evolution, our population is dominated by massive giant planets and brown dwarfs at large semimajor axis, which direct imaging surveys should, but only rarely, detect. Finally, disc fragmentation is shown to be an efficient manufacturer of free-floating planetary mass objects, and the typical multiplicity of systems formed via gravitational instability will be low.

  13. Fragmentation of size-selected Xe clusters: Why does the monomer ion channel dominate the Xen and Krn ionization?

    Czech Academy of Sciences Publication Activity Database

    Poterya, Viktoriya; Fárník, Michal; Buck, U.; Bonhomommeneau, D.; Halberstadt, N.

    2009-01-01

    Roč. 280, 1-3 (2009), s. 78-84 ISSN 1387-3806 R&D Projects: GA AV ČR KAN400400651; GA ČR GA203/06/1290 Institutional research plan: CEZ:AV0Z40400503 Keywords : cluster * fragmentation * ionization * molecular beam scattering Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.117, year: 2009

  14. Monitoring and control system for tuneable high frequency microwave assisted chemistry

    International Nuclear Information System (INIS)

    Lewis, G P; Wylie, S R; Shaw, A; Al-Shamma'a, A I; Phipps, D; Alkhaddar, R; Bond, G

    2007-01-01

    Microwave chemistry is an established technique in the synthesis of organic compounds at a frequency of 2.45 GHz. This is considered to be a result of the development of microwave ovens, rather than an objective solution, which maximises efficiency through careful selection of the operating frequency. To obtain a frequency for a dielectric, the complex permittivity should be determined as a function of frequency. If the correct heating frequency is found, superheating can occur when a liquid solvent reaches its boiling point and exceeds it. This paper presents sensor diodes and temperature sensors used in a mono-mode reactor, with computer control of an E-H tuner, frequency and incident power to control temperature and power, experimental results showing heating and reactions using ethanol are reported

  15. Molecular-level chemistry of model single-crystal oxide surfaces with model halogenated compounds

    Science.gov (United States)

    Adib, Kaveh

    Synchrotron-based X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption (TPD) and low energy electron diffraction (LEED) have been used to investigate, at a molecular level, the chemistry of different terminations of single crystal iron-oxide surfaces with probe molecules (CCl4 and D2O). Comparisons of the reactivity of these surfaces towards CCl4, indicate that the presence of an uncapped surface Fe cation (strong Lewis acid site) and an adjacent oxygen site capped by that cation can effect the C-Cl bond cleavage in CCl4, resulting in dissociatively adsorbed Cl-adatoms and carbon-containing fragments. If in addition to these sites, an uncapped surface oxygen (Lewis base) site is also available, the carbon-containing moiety can then move that site, coordinate itself with that uncapped oxygen, and stabilize itself. At a later step, the carbon-containing fragment may form a strong covalent bond with the uncapped oxygen and may even abstract that surface oxygen. On the other hand, if an uncapped oxygen is not available to stabilize the carbon-containing fragment, the surface coordination will not occur and upon the subsequent thermal annealing of the surface the Cl-adatoms and the carbon-containing fragments will recombine and desorb as CCl4. Finally, the presence of surface deuteroxyls blocking the strong Lewis acid and base sites of the reactive surface, passivates this surface. Such a deuteroxylated surface will be unreactive towards CCl 4. Such a molecular level understanding of the surface chemistry of metal-oxides will have applications in the areas of selective catalysis, including environmental catalysis, and chemical sensor technology.

  16. Primary and secondary fragmentation of crystal-bearing intermediate magma

    Science.gov (United States)

    Jones, Thomas J.; McNamara, Keri; Eychenne, Julia; Rust, Alison C.; Cashman, Katharine V.; Scheu, Bettina; Edwards, Robyn

    2016-11-01

    Crystal-rich intermediate magmas are subjected to both primary and secondary fragmentation processes, each of which may produce texturally distinct tephra. Of particular interest for volcanic hazards is the extent to which each process contributes ash to volcanic plumes. One way to address this question is by fragmenting pyroclasts under controlled conditions. We fragmented pumice samples from Soufriere Hills Volcano (SHV), Montserrat, by three methods: rapid decompression in a shock tube-like apparatus, impact by a falling piston, and milling in a ball mill. Grain size distributions of the products reveal that all three mechanisms produce fractal breakage patterns, and that the fractal dimension increases from a minimum of 2.1 for decompression fragmentation (primary fragmentation) to a maximum of 2.7 by repeated impact (secondary fragmentation). To assess the details of the fragmentation process, we quantified the shape, texture and components of constituent ash particles. Ash shape analysis shows that the axial ratio increases during milling and that particle convexity increases with repeated impacts. We also quantify the extent to which the matrix is separated from the crystals, which shows that secondary processes efficiently remove adhering matrix from crystals, particularly during milling (abrasion). Furthermore, measurements of crystal size distributions before (using x-ray computed tomography) and after (by componentry of individual grain size classes) decompression-driven fragmentation show not only that crystals influence particular size fractions across the total grain size distribution, but also that free crystals are smaller in the fragmented material than in the original pumice clast. Taken together, our results confirm previous work showing both the control of initial texture on the primary fragmentation process and the contributions of secondary processes to ash formation. Critically, however, our extension of previous analyses to characterisation

  17. Universal elements of fragmentation

    International Nuclear Information System (INIS)

    Yanovsky, V. V.; Tur, A. V.; Kuklina, O. V.

    2010-01-01

    A fragmentation theory is proposed that explains the universal asymptotic behavior of the fragment-size distribution in the large-size range, based on simple physical principles. The basic principles of the theory are the total mass conservation in a fragmentation process and a balance condition for the energy expended in increasing the surface of fragments during their breakup. A flux-based approach is used that makes it possible to supplement the basic principles and develop a minimal theory of fragmentation. Such a supplementary principle is that of decreasing fragment-volume flux with increasing energy expended in fragmentation. It is shown that the behavior of the decreasing flux is directly related to the form of a power-law fragment-size distribution. The minimal theory is used to find universal asymptotic fragment-size distributions and to develop a natural physical classification of fragmentation models. A more general, nonlinear theory of strong fragmentation is also developed. It is demonstrated that solutions to a nonlinear kinetic equation consistent with both basic principles approach a universal asymptotic size distribution. Agreement between the predicted asymptotic fragment-size distributions and experimental observations is discussed.

  18. NMR-Fragment Based Virtual Screening: A Brief Overview.

    Science.gov (United States)

    Singh, Meenakshi; Tam, Benjamin; Akabayov, Barak

    2018-01-25

    Fragment-based drug discovery (FBDD) using NMR has become a central approach over the last twenty years for development of small molecule inhibitors against biological macromolecules, to control a variety of cellular processes. Yet, several considerations should be taken into account for obtaining a therapeutically relevant agent. In this review, we aim to list the considerations that make NMR fragment screening a successful process for yielding potent inhibitors. Factors that may govern the competence of NMR in fragment based drug discovery are discussed, as well as later steps that involve optimization of hits obtained by NMR-FBDD.

  19. NMR-Fragment Based Virtual Screening: A Brief Overview

    Directory of Open Access Journals (Sweden)

    Meenakshi Singh

    2018-01-01

    Full Text Available Fragment-based drug discovery (FBDD using NMR has become a central approach over the last twenty years for development of small molecule inhibitors against biological macromolecules, to control a variety of cellular processes. Yet, several considerations should be taken into account for obtaining a therapeutically relevant agent. In this review, we aim to list the considerations that make NMR fragment screening a successful process for yielding potent inhibitors. Factors that may govern the competence of NMR in fragment based drug discovery are discussed, as well as later steps that involve optimization of hits obtained by NMR-FBDD.

  20. Molecular dynamics for irradiation driven chemistry: application to the FEBID process*

    Science.gov (United States)

    Sushko, Gennady B.; Solov'yov, Ilia A.; Solov'yov, Andrey V.

    2016-10-01

    A new molecular dynamics (MD) approach for computer simulations of irradiation driven chemical transformations of complex molecular systems is suggested. The approach is based on the fact that irradiation induced quantum transformations can often be treated as random, fast and local processes involving small molecules or molecular fragments. We advocate that the quantum transformations, such as molecular bond breaks, creation and annihilation of dangling bonds, electronic charge redistributions, changes in molecular topologies, etc., could be incorporated locally into the molecular force fields that describe the classical MD of complex molecular systems under irradiation. The proposed irradiation driven molecular dynamics (IDMD) methodology is designed for the molecular level description of the irradiation driven chemistry. The IDMD approach is implemented into the MBN Explorer software package capable to operate with a large library of classical potentials, many-body force fields and their combinations. IDMD opens a broad range of possibilities for modelling of irradiation driven modifications and chemistry of complex molecular systems ranging from radiotherapy cancer treatments to the modern technologies such as focused electron beam deposition (FEBID). As an example, the new methodology is applied for studying the irradiation driven chemistry caused by FEBID of tungsten hexacarbonyl W(CO)6 precursor molecules on a hydroxylated SiO2 surface. It is demonstrated that knowing the interaction parameters for the fragments of the molecular system arising in the course of irradiation one can reproduce reasonably well experimental observations and make predictions about the morphology and molecular composition of nanostructures that emerge on the surface during the FEBID process.

  1. Maintenance, outages and chemistry really can be compatible

    International Nuclear Information System (INIS)

    Roberts, J.G.; Deaconescu, R.

    2006-01-01

    'Full text:' In their address to the Canadian Nuclear Society, Bruce Power's Chemistry Design staff will describe how maintenance and outages can impact negatively on chemistry control and asset protection. Considerations of material impacts and material condition have significant influences on the approach to, and control of, chemistry. This applies equally to operation as it does during unit and/or system outages. Ideas will be presented as to how to facilitate making maintenance, outages and chemistry compatible. It will be shown how the lack of such an approach can lead to disastrous results. (author)

  2. Water chemistry and corrosion control of cladding and primary circuit components. Proceedings of a technical committee meeting

    International Nuclear Information System (INIS)

    1999-12-01

    Corrosion is the principal life limiting degradation mechanism in nuclear steam supply systems, especially taking into account the trends to increase fuel burnup, thermal rate and cycle length. Primary circuit components of water cooled power reactors have an impact on Zr-based alloys behaviour due to crud (primary circuit corrosion products) formation, transport and deposition on heat transfer surfaces. Crud deposits influence water chemistry, radiation and thermal hydraulic conditions near cladding surface, and by this way-Zr-based alloy corrosion. During the last decade, significant improvements were achieved in the reduction of the corrosion and dose rates by changing the cladding material for one more resistant to corrosion or by the improvement of water chemistry conditions. However, taking into account the above mentioned tendency for heavier fuel duties, corrosion and water chemistry, control will remain a serious task to work with for nuclear power plant operators and scientists, as well as development of generally accepted corrosion model of Zr-based alloys in a water environment in a new millennium. Upon the recommendation of the International Working Group on Water Reactor Fuel Performance and Technology, water chemistry and corrosion of cladding and primary circuit components are in the focus of the IAEA activities in the area of fuel technology and performance. At present the IAEA performs two co-ordinated research projects (CRPs): on On-line High Temperature Monitoring of Water Chemistry and Corrosion (WACOL) and on Activity Transport in Primary Circuits. Two CRPs deal with hydrogen and hydride degradation of the Zr-based alloys. A state-of-the-art review entitled: 'Waterside Corrosion of Zirconium Alloys in Nuclear Power Plants' was published in 1998. Technical Committee meetings on the subject were held in 1985 (Cadarache, France), 1989 (Portland, USA), 1993 (Rez, Czech Republic). During the last few years extensive exchange of experience in

  3. Chemistry management system for nuclear power plants

    International Nuclear Information System (INIS)

    Nagasawa, Katsumi; Maeda, Katsuji

    1998-01-01

    Recently, the chemistry management in the nuclear power plants has been changing from the problem solution to the predictive diagnosis and maintenance. It is important to maintain the integrity of plant operation by an adequate chemistry control. For these reasons, many plant operation data and chemistry analysis data should be collected and treated effectively to evaluate chemistry condition of the nuclear power plants. When some indications of chemistry anomalies occur, quick and effective root cause evaluation and countermeasures should be required. The chemistry management system has been developed as to provide sophisticate chemistry management in the nuclear power plants. This paper introduces the concept and functions of the chemistry management system for the nuclear power plants. (author)

  4. Ionic fragmentation of the isoprene molecule in the VUV energy range (12 to 310 eV)

    Energy Technology Data Exchange (ETDEWEB)

    Bernini, R.B., E-mail: rafael.bernini@ifrj.edu.br [Instituto Federal de Ciência e Tecnologia do Rio de Janeiro (IFRJ), 25050-100 Duque de Caxias, RJ (Brazil); Coutinho, L.H. [Instituto de Física, Universidade Federal do Rio De Janeiro (UFRJ), 21941-972 Rio de Janeiro, RJ (Brazil); Nunez, C.V. [Laboratório de Bioprospecção e Biotecnologia, Coordenação de Tecnologia e Inovação, Instituto Nacional de Pesquisas da Amazônia (INPA), 69060-001 Manaus, AM (Brazil); Castilho, R.B. de [Departamento de Química, Instituto de Ciências Exatas, Universidade Federal do Amazonas (UFAM), 69077-000 Manaus, AM (Brazil); Souza, G.G.B. de [Instituto de Química, Universidade Federal do Rio de Janeiro (UFRJ), 21949-900 Rio de Janeiro, RJ (Brazil)

    2015-07-15

    Highlights: • Ionic fragmentation of isoprene following valence-shell and C 1s excitation. • Experimental observation of single and double ionization processes. • Large increase in fragmentation following core excitation. • Similar dissociation pattern bellow (270 eV) and above (310 eV) core edge. • Stable molecular ion observed at all photon energies. - Abstract: Isoprene, C{sub 5}H{sub 8}, is a biogenic volatile compound emitted from plants and animals, playing an important role in atmospheric chemistry. In this work, we have studied the ionic fragmentation of the isoprene molecule induced by high energy photons (synchrotron radiation), both at the valence (12.0, 14.0, 16.0, 18.0, and 21.0 eV) and carbon 1s edge (270 and 310 eV, respectively, below and above edge) energies. The ionic fragments were mass-analyzed using a Wiley–McLaren time-of-flight spectrometer (TOF) and single (PEPICO) and double ionization coincidence (PEPIPICO) spectra were obtained. As expected, the fragmentation degree increases with increasing energy. Below and above the carbon 1s edge, the fragmentation patterns are quite similar, and basically the same fragments are observed as compared to the spectra following valence-shell ionization. Stable doubly-charged ions were not observed. A PEPIPICO spectrum has shown that the main dissociation route for doubly-ionized species corresponds to the [CH{sub 3}]{sup +}/[C{sub 4}H{sub 2–5}]{sup +} ion pair. Intense fragmentation of the isoprene molecule has been observed following valence shell and core electron ionization. The observance of basically the same fragments when moving from valence to inner-shell suggests that basically the same fragmentation routes are present in both cases. All doubly (or multiply)-charged cations are unstable, at least on a microsecond scale.

  5. Diverse Effects of a Seven-Year Experimental Grassland Fragmentation on Major Invertebrate Groups.

    Science.gov (United States)

    Braschler, Brigitte; Baur, Bruno

    2016-01-01

    Habitat fragmentation is a major driver of biodiversity loss, but observed effects vary and may depend on the group examined. Time since fragmentation may explain some differences between taxonomical groups, as some species and thus species composition respond with a delay to changes in their environment. Impacts of drivers of global change may thus be underestimated in short-term studies. In our study we experimentally fragmented nutrient-poor dry calcareous grasslands and studied the response of species richness, individual density and species composition of various groups of invertebrates (gastropods, ants, ground beetles, rove beetles, orthoptera, spiders, woodlice) in 12 small (1.5 m * 1.5 m) and 12 large (4.5 m * 4.5 m) fragments and their corresponding control plots after 7 years. We further examined responses to fragmentation in relation to body size and habitat preferences. Responses to fragmentation varied between taxonomical groups. While spider species richness and individual density were lower in fragments, the opposite was true for an orthopteran species and woodlice. Species composition and β-diversity differed between fragments and control plots for some groups. However, the interaction treatment*plot size was rarely significant. Species with high occupancy rates in undisturbed control plots responded more negatively to the fragmentation, while species with large body size were relatively more abundant in fragments in some groups. No effect of the fragmentation was found for ants, which may have the longest lag times because of long-lived colonies. However, relationships between abundance and the species' preferences for environmental factors affected by edge effects indicate that ant diversity too may be affected in the longer-term. Our results show the importance of considering different groups in conservation management in times of widespread fragmentation of landscapes. While species richness may respond slowly, changes in abundance related to

  6. Advanced studies in chemistry control with morpholine

    International Nuclear Information System (INIS)

    Riddle, J.M.

    1992-07-01

    Prior studies at Beaver Valley Unit 1 and at Prairie Island found that the substitution of morpholine for ammonia reduced corrosion and iron transport in the feedtrain of pressurized water reactors. The benefits of using morpholine encouraged other utilities to consider morpholine water chemistry. Calvert Cliffs Unit 1 was the first domestic PWR with deep-bed condensate polishers to use morpholine water chemistry. Typically a bed is operated in the hydrogen cycle for eight to ten days, followed by an additional 25 days in the morpholine cycle. Morpholine reduced feedwater iron levels by 28 percent. With morpholine treatment at Calvert Cliffs Unit 1, corrosion product transport in feedwater was reduced by a factor of 1.3 -- 1.4. Morpholine treatment at higher levels at Prairie Island Unit 2 provided a factor of 2.3 reduction in feedwater iron transport, in agreement with data from Electricity de France. EdF data show that the factor increases as the pH for ammonia chemistry is reduced from 9.5. When possible, the factors were compared at a pH of 9.2 for morpholine at room temperature. Aqueous solutions of morpholine thermally decompose at increasing rates with temperature above about 288 degree C (550 degree F). Oxygen and several metal oxides appear to increase the rate of decomposition to a small extent. Acetate, formate, and various amines, including ammonia, are the principal decomposition products

  7. An approach to quality and performance control in a computer-assisted clinical chemistry laboratory.

    Science.gov (United States)

    Undrill, P E; Frazer, S C

    1979-01-01

    A locally developed, computer-based clinical chemistry laboratory system has been in operation since 1970. This utilises a Digital Equipment Co Ltd PDP 12 and an interconnected PDP 8/F computer. Details are presented of the performance and quality control techniques incorporated into the system. Laboratory performance is assessed through analysis of results from fixed-level control sera as well as from cumulative sum methods. At a simple level the presentation may be considered purely indicative, while at a more sophisticated level statistical concepts have been introduced to aid the laboratory controller in decision-making processes. PMID:438340

  8. Water chemistry guidelines for BWRs

    International Nuclear Information System (INIS)

    Bilanin, W.J.; Jones, R.L.; Welty, C.S.

    1984-01-01

    Guidelines for BWR water chemistry control have been prepared by a committee of experienced utility industry personnel sponsored by the BWR Owners Group on IGSCC Research and coordinated by the Electric Power Research Institute. The guidelines are based on extensive plant operational experience and laboratory research data. The purpose of the guidelines is to provide guidance to the electric utility industry on water chemistry control to help reduce corrosion, especially stress corrosion cracking, in boiling water reactors

  9. DOE fundamentals handbook: Chemistry

    International Nuclear Information System (INIS)

    1993-01-01

    The Chemistry Handbook was developed to assist nuclear facility operating contractors in providing operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding of chemistry. The handbook includes information on the atomic structure of matter; chemical bonding; chemical equations; chemical interactions involved with corrosion processes; water chemistry control, including the principles of water treatment; the hazards of chemicals and gases, and basic gaseous diffusion processes. This information will provide personnel with a foundation for understanding the chemical properties of materials and the way these properties can impose limitations on the operation of equipment and systems

  10. Interpreting closed-loop learning control of molecular fragmentation in terms of wave-packet dynamics and enhanced molecular ionization

    International Nuclear Information System (INIS)

    Cardoza, David; Baertschy, Mark; Weinacht, Thomas

    2005-01-01

    We interpret a molecular fragmentation experiment using shaped, ultrafast laser pulses in terms of enhanced molecular ionization during dissociation. A closed-loop learning control experiment was performed to maximize the CF 3 + /CH 3 + production ratio in the dissociative ionization of CH 3 COCF 3 . Using ab inito molecular structure calculations and quasistatic molecular ionization calculations along with data from pump-probe experiments, we identify the primary control mechanism which is quite general and should be applicable to a broad class of molecules

  11. Chemistry Programme for Water Cooled Nuclear Power Plants. Specific Safety Guide

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-01-15

    This publication provides guidance on establishing a high standard chemistry programme in accordance with plant safety policy and regulatory requirements. It will be useful to managers of operating organizations and other staff responsible for supporting or monitoring plant activities and for oversight of the plant chemistry programme, as well as to regulatory bodies. Contents: 1. Introduction; 2. Functions, responsibilities and interfaces; 3. Chemistry programme; 4. Chemistry control; 5. Chemistry aspects of radiation exposure optimization; 6. Chemistry surveillance; 7. Management of chemistry data; 8. Training and qualification; 9. Quality control of chemicals and other substances.

  12. Chemistry Programme for Water Cooled Nuclear Power Plants. Specific Safety Guide

    International Nuclear Information System (INIS)

    2011-01-01

    This publication provides guidance on establishing a high standard chemistry programme in accordance with plant safety policy and regulatory requirements. It will be useful to managers of operating organizations and other staff responsible for supporting or monitoring plant activities and for oversight of the plant chemistry programme, as well as to regulatory bodies. Contents: 1. Introduction; 2. Functions, responsibilities and interfaces; 3. Chemistry programme; 4. Chemistry control; 5. Chemistry aspects of radiation exposure optimization; 6. Chemistry surveillance; 7. Management of chemistry data; 8. Training and qualification; 9. Quality control of chemicals and other substances

  13. Geochemical controls on groundwater chemistry in shales

    International Nuclear Information System (INIS)

    Von Damm, K.L.

    1989-01-01

    The chemistry of groundwaters is one of the most important parameters in determining the mobility of species within a rock formation. A three pronged approach was used to determine the composition of, and geochemical controls, on groundwaters specifically within shale formations: (1) available data were collected from the literature, the US Geological Survey WATSTORE data base, and field sampling, (2) the geochemical modeling code EQ3/6 was used to simulate interaction of various shales and groundwaters, and (3) several types of shale were reacted with synthetic groundwaters in the laboratory. The comparison of model results to field and laboratory data provide a means of validating the models, as well as a means of deconvoluting complex field interactions. Results suggest that groundwaters in shales have a wide range in composition and are primarily of the Na-Cl-HCO 3 - type. The constancy of the Na:Cl (molar) ratio at 1:1 and the Ca:Mg ratio from 3:1 to 1:1 suggests the importance of halite and carbonates in controlling groundwater compositions. In agreement with the reaction path modeling, most of the groundwaters are neutral to slightly alkaline at low temperatures. Model and experimental results suggest that reaction (1) at elevated temperatures, or (2) in the presence of oxygen will lead to more acidic conditions. Some acetate was found to be produced in the experiments; depending on the constraints applied, large amounts of acetate were produced in the model results. 13 refs., 1 tab

  14. Field and laboratory emission cell automation and control system for investigating surface chemistry reactions

    Science.gov (United States)

    Flemmer, Michael M.; Ham, Jason E.; Wells, J. R.

    2007-01-01

    A novel system [field and laboratory emission cell (FLEC) automation and control system] has been developed to deliver ozone to a surface utilizing the FLEC to simulate indoor surface chemistry. Ozone, humidity, and air flow rate to the surface were continuously monitored using an ultraviolet ozone monitor, humidity, and flow sensors. Data from these sensors were used as feedback for system control to maintain predetermined experimental parameters. The system was used to investigate the chemistry of ozone with α-terpineol on a vinyl surface over 72h. Keeping all other experimental parameters the same, volatile organic compound emissions from the vinyl tile with α-terpineol were collected from both zero and 100ppb(partsper109) ozone exposures. System stability profiles collected from sensor data indicated experimental parameters were maintained to within a few percent of initial settings. Ozone data from eight experiments at 100ppb (over 339h) provided a pooled standard deviation of 1.65ppb and a 95% tolerance of 3.3ppb. Humidity data from 17 experiments at 50% relative humidity (over 664h) provided a pooled standard deviation of 1.38% and a 95% tolerance of 2.77%. Data of the flow rate of air flowing through the FLEC from 14 experiments at 300ml/min (over 548h) provided a pooled standard deviation of 3.02ml/min and a 95% tolerance range of 6.03ml/min. Initial experimental results yielded long term emissions of ozone/α-terpineol reaction products, suggesting that surface chemistry could play an important role in indoor environments.

  15. Improved water chemistry controls for minimizing degradation of materials

    International Nuclear Information System (INIS)

    Sawochka, S.G.

    1986-01-01

    The Electric Power Research Institute and the Steam Generator Owners Group have sponsored several efforts to develop secondary water chemistry guidelines to minimize pressurized water reactor (PWR) steam generator tubing degradation. To develop these guidelines, chemical species known to accelerate corrosion of Alloy 600 were identified, and values for normal and abnormal chemistry situations were established. For example, sodium hydroxide was known to accelerate Alloy 600 intergranular attack stress corrosion cracking; thus, guidelines were developed for blowdown sodium concentrations in recirculating steam generator systems. Similarly, formation of acidic solutions, particularly as a result of chloride ingress at seawater sites, was known to accelerate denting; thus, chloride guidelines were established. A blowdown cation conductivity limit was established to minimize concentrations of other anionic species. Guidelines also were developed for condensate and feedwater chemistry to minimize general corrosion of system materials, thereby minimizing sludge and deposit buildup in the steam generators

  16. Maintenance, outages and chemistry really can be compatible

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, J.G.; Deaconescu, R. [Bruce Power, Tiverton, Ontario (Canada)

    2006-07-01

    'Full text:' In their address to the Canadian Nuclear Society, Bruce Power's Chemistry Design staff will describe how maintenance and outages can impact negatively on chemistry control and asset protection. Considerations of material impacts and material condition have significant influences on the approach to, and control of, chemistry. This applies equally to operation as it does during unit and/or system outages. Ideas will be presented as to how to facilitate making maintenance, outages and chemistry compatible. It will be shown how the lack of such an approach can lead to disastrous results. (author)

  17. Rock fragment distributions and regolith evolution in the Ouachita Mountains, Arkansas, USA

    Science.gov (United States)

    Jonathan D. Phillips; Ken Luckow; Daniel A. Marion; Kristin R. Adams

    2005-01-01

    Rock fragments in the regolith are a persistent property that reflects the combined influences of geologic controls, erosion, deposition, bioturbation, and weathering. The distribution of rock fragments in regoliths of the Ouachita Mountains, Arkansas, shows that sandstone fragments are common in all layers, even if sandstone is absent in parent material. Shale and...

  18. BWR plant-to-fleet water chemistry trends -- Past and present

    International Nuclear Information System (INIS)

    Baston, V.F.; Sundberg, L.L.; Huff, J.M.

    1995-01-01

    Good water chemistry control is important for the integrity and satisfactory performance of BWRs. A historical review of selected chemistry performance indicators (e.g., conductivity) illustrates the improved chemistry control today relative to that in the past as well as the ability to evaluate these operational indicators

  19. Fragmentation cross sections outside the limiting-fragmentation regime

    CERN Document Server

    Sümmerer, K

    2003-01-01

    The empirical parametrization of fragmentation cross sections, EPAX, has been successfully applied to estimate fragment production cross sections in reactions of heavy ions at high incident energies. It is checked whether a similar parametrization can be found for proton-induced spallation around 1 GeV, the range of interest for ISOL-type RIB facilities. The validity of EPAX for medium-energy heavy-ion induced reactions is also checked. Only a few datasets are available, but in general EPAX predicts the cross sections rather well, except for fragments close to the projectile, where the experimental cross sections are found to be larger.

  20. Universality of fragment shapes.

    Science.gov (United States)

    Domokos, Gábor; Kun, Ferenc; Sipos, András Árpád; Szabó, Tímea

    2015-03-16

    The shape of fragments generated by the breakup of solids is central to a wide variety of problems ranging from the geomorphic evolution of boulders to the accumulation of space debris orbiting Earth. Although the statistics of the mass of fragments has been found to show a universal scaling behavior, the comprehensive characterization of fragment shapes still remained a fundamental challenge. We performed a thorough experimental study of the problem fragmenting various types of materials by slowly proceeding weathering and by rapid breakup due to explosion and hammering. We demonstrate that the shape of fragments obeys an astonishing universality having the same generic evolution with the fragment size irrespective of materials details and loading conditions. There exists a cutoff size below which fragments have an isotropic shape, however, as the size increases an exponential convergence is obtained to a unique elongated form. We show that a discrete stochastic model of fragmentation reproduces both the size and shape of fragments tuning only a single parameter which strengthens the general validity of the scaling laws. The dependence of the probability of the crack plan orientation on the linear extension of fragments proved to be essential for the shape selection mechanism.

  1. The role of cation exchange in controlling groundwater chemistry at Aspo, Sweden

    International Nuclear Information System (INIS)

    Viani, B.E.; Bruton, C.J.

    1995-01-01

    Construction-induced groundwater flow has resulted in the mixing of relatively dilute shallow groundwater with more concentrated groundwater at depth in the underground Hard Rock Laboratory (HRL) at Aespoe, Sweden. The observed compositional variation of the mixed groundwater cannot be explained using a conservative mixing model. The geochemical modeling package EQ3/6, to which a cation-exchange model was added, was used to simulate mixing between the two fluids. The results of modeling simulations suggest that cation exchange between groundwater and fracture-lining clays can explain the major element fluid chemistry observed in the HRL. The quantity of exchanger required to match simulated with observed fluid chemistry is reasonable and is consistent with the observed fracture mineralogy. This preliminary study establishes cation exchange as a viable mechanism for controlling the chemical evolution of groundwaters in a fracture-dominated dynamic flow system. This modeling study also strengthens their confidence in the ability to model the potential effects of fracture-lining minerals on the transport of radionuclides in a high level nuclear waste repository

  2. Anomalous nuclear fragments

    International Nuclear Information System (INIS)

    Karmanov, V.A.

    1983-01-01

    Experimental data are given, the status of anomalon problem is discussed, theoretical approaches to this problem are outlined. Anomalons are exotic objects formed following fragmentation of nuclei-targets under the effect of nuclei - a beam at the energy of several GeV/nucleon. These nuclear fragments have an anomalously large cross section of interaction and respectively, small free path, considerably shorter than primary nuclei have. The experimental daa are obtained in accelerators following irradiation of nuclear emulsions by 16 O, 56 Fe, 40 Ar beams, as well as propane by 12 C beams. The experimental data testify to dependence of fragment free path on the distance L from the point of the fragment formation. A decrease in the fragment free path is established more reliably than its dependence on L. The problem of the anomalon existence cannot be yet considered resolved. Theoretical models suggested for explanation of anomalously large cross sections of nuclear fragment interaction are variable and rather speculative

  3. Controlling chemistry parameters in nuclear reactors and power plants, plant chemistry specification requirements and compliance - an overview of TAPS 1 and 2 experiences

    International Nuclear Information System (INIS)

    Ravindranath; Muralidharan, K.; Save, C.B.; Patil, D.P.

    2006-01-01

    Tarapur Atomic Power Station -TAPS 1 and 2 is a twin unit Boiling Water Reactor (BWR) Nuclear Power Plant commissioned in the year 1969. Both units are running with capacity factor of more than 90 % in their 20 th cycle of operation as on today. The 220 MWe units were derated to 160 MWe during 1984 consequent to isolation of Secondary Steam Generators (SSG) in the 10 th cycle of operation due to SSG tube leaks. This paper presents an overview of Plant Chemistry Control measures and experiences during the last 38 years of operation. The overall plant chemistry performance of TAPS 1 and 2 observed is very good; which is evident from the material condition of various systems reflected in QC and I reports, NDT and ISI reports. This is also supported by the fact that both Units are showing excellent performance continuously during recent years. (author)

  4. BWR water chemistry guidelines and PWR primary water chemistry guidelines in Japan – Purpose and technical background

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, Hirotaka, E-mail: kawamuh@criepi.denken.or.jp [Central Research Institute of Electric Power Industry (Japan); Hirano, Hideo [Central Research Institute of Electric Power Industry (Japan); Katsumura, Yousuke [University of Tokyo (Japan); Uchida, Shunsuke [Tohoku University (Japan); Mizuno, Takayuki [Mie University (Japan); Kitajima, Hideaki; Tsuzuki, Yasuo [Japan Nuclear Safety Institute (Japan); Terachi, Takumi [Institute of Nuclear Safety System, Inc. (Japan); Nagase, Makoto; Usui, Naoshi [Hitachi-GE Nuclear Energy, Ltd. (Japan); Takagi, Junichi; Urata, Hidehiro [Toshiba Corporation (Japan); Shoda, Yasuhiko; Nishimura, Takao [Mitsubishi Heavy Industry, Ltd. (Japan)

    2016-12-01

    Highlights: • Framework of BWR/PWR water chemistry Guidelines in Japan are presented. • Guideline necessity, definitions, philosophy and technical background are mentioned. • Some guideline settings for control parameters and recommendations are explaines. • Chemistry strategy is also mentioned. - Abstract: After 40 years of light water reactor (LWR) operations in Japan, the sustainable development of water chemistry technologies has aimed to ensure the highest coolant system component integrity and fuel reliability performance for maintaining LWRs in the world; additionally, it aimed to achieve an excellent dose rate reduction. Although reasonable control and diagnostic parameters are utilized by each boiling water reactor (BWR) and pressurized water reactor (PWR) owner, it is recognized that specific values are not shared among everyone involved. To ensure the reliability of BWR and PWR operation and maintenance, relevant members of the Atomic Energy Society of Japan (AESJ) decided to establish guidelines for water chemistry. The Japanese BWR and PWR water chemistry guidelines provide strategies to improve material and fuel reliability performance as well as to reduce dosing rates. The guidelines also provide reasonable “control values”, “diagnostic values” and “action levels” for multiple parameters, and they stipulate responses when these levels are exceeded. Specifically, “conditioning parameters” are adopted in the Japanese PWR primary water chemistry guidelines. Good practices for operational conditions are also discussed with reference to long-term experience. This paper presents the purpose, technical background and framework of the preliminary water chemistry guidelines for Japanese BWRs and PWRs. It is expected that the guidelines will be helpful as an introduction to achieve safety and reliability during operations.

  5. Nonlinear transient responses of beams and rings to impulse loading or fragment impact

    International Nuclear Information System (INIS)

    Witmer, E.A.; Stagliano, T.R.; Rodal, J.J.A.

    1977-01-01

    Nuclear power plant protective structures may be subjected to various external missiles such as aircraft and tornado-generated missiles: telephone poles, planks, pipes, rods, automobiles, and other blown vehicles. Also, 'internally-generated missiles' such as fragments from powerplant rotors and aircraft engine rotors may impact protective structures. The present paper is concerned with a very limited part of the cited fragment threat; namely, fragments from high speed rotating machinery such as (1) aircraft engine rotors and (2) stationary power plant turbine rotors. Further, it is assumed that the structures intended to contain or control these fragments consist of initially-isotopic elastic-plastic metals. Certain potential containment/control (C/C) structures behave in a planar (or two-dimensional) fashion while other fragment-attacked C/C structures will undergo general three-dimensional deformations. Predictions for only the former category of fragment-attacked structures are discussed in the present paper. Pertinent experimental data discussed on fragment-attacked structures include (a) steel-sphere impact data involving beam targets and (b) engine rotor fragment impact against a steel containment ring. In all of these cases large-deflection, elastic-plastic transient structural responses occur. (Auth.)

  6. Quality Control Practices for Chemistry and Immunochemistry in a Cohort of 21 Large Academic Medical Centers.

    Science.gov (United States)

    Rosenbaum, Matthew W; Flood, James G; Melanson, Stacy E F; Baumann, Nikola A; Marzinke, Mark A; Rai, Alex J; Hayden, Joshua; Wu, Alan H B; Ladror, Megan; Lifshitz, Mark S; Scott, Mitchell G; Peck-Palmer, Octavia M; Bowen, Raffick; Babic, Nikolina; Sobhani, Kimia; Giacherio, Donald; Bocsi, Gregary T; Herman, Daniel S; Wang, Ping; Toffaletti, John; Handel, Elizabeth; Kelly, Kathleen A; Albeiroti, Sami; Wang, Sihe; Zimmer, Melissa; Driver, Brandon; Yi, Xin; Wilburn, Clayton; Lewandrowski, Kent B

    2018-05-29

    In the United States, minimum standards for quality control (QC) are specified in federal law under the Clinical Laboratory Improvement Amendment and its revisions. Beyond meeting this required standard, laboratories have flexibility to determine their overall QC program. We surveyed chemistry and immunochemistry QC procedures at 21 clinical laboratories within leading academic medical centers to assess if standardized QC practices exist for chemistry and immunochemistry testing. We observed significant variation and unexpected similarities in practice across laboratories, including QC frequency, cutoffs, number of levels analyzed, and other features. This variation in practice indicates an opportunity exists to establish an evidence-based approach to QC that can be generalized across institutions.

  7. High Efficiency Hydrodynamic DNA Fragmentation in a Bubbling System.

    Science.gov (United States)

    Li, Lanhui; Jin, Mingliang; Sun, Chenglong; Wang, Xiaoxue; Xie, Shuting; Zhou, Guofu; van den Berg, Albert; Eijkel, Jan C T; Shui, Lingling

    2017-01-18

    DNA fragmentation down to a precise fragment size is important for biomedical applications, disease determination, gene therapy and shotgun sequencing. In this work, a cheap, easy to operate and high efficiency DNA fragmentation method is demonstrated based on hydrodynamic shearing in a bubbling system. We expect that hydrodynamic forces generated during the bubbling process shear the DNA molecules, extending and breaking them at the points where shearing forces are larger than the strength of the phosphate backbone. Factors of applied pressure, bubbling time and temperature have been investigated. Genomic DNA could be fragmented down to controllable 1-10 Kbp fragment lengths with a yield of 75.30-91.60%. We demonstrate that the ends of the genomic DNAs generated from hydrodynamic shearing can be ligated by T4 ligase and the fragmented DNAs can be used as templates for polymerase chain reaction. Therefore, in the bubbling system, DNAs could be hydrodynamically sheared to achieve smaller pieces in dsDNAs available for further processes. It could potentially serve as a DNA sample pretreatment technique in the future.

  8. Diverse Effects of a Seven-Year Experimental Grassland Fragmentation on Major Invertebrate Groups.

    Directory of Open Access Journals (Sweden)

    Brigitte Braschler

    Full Text Available Habitat fragmentation is a major driver of biodiversity loss, but observed effects vary and may depend on the group examined. Time since fragmentation may explain some differences between taxonomical groups, as some species and thus species composition respond with a delay to changes in their environment. Impacts of drivers of global change may thus be underestimated in short-term studies. In our study we experimentally fragmented nutrient-poor dry calcareous grasslands and studied the response of species richness, individual density and species composition of various groups of invertebrates (gastropods, ants, ground beetles, rove beetles, orthoptera, spiders, woodlice in 12 small (1.5 m * 1.5 m and 12 large (4.5 m * 4.5 m fragments and their corresponding control plots after 7 years. We further examined responses to fragmentation in relation to body size and habitat preferences. Responses to fragmentation varied between taxonomical groups. While spider species richness and individual density were lower in fragments, the opposite was true for an orthopteran species and woodlice. Species composition and β-diversity differed between fragments and control plots for some groups. However, the interaction treatment*plot size was rarely significant. Species with high occupancy rates in undisturbed control plots responded more negatively to the fragmentation, while species with large body size were relatively more abundant in fragments in some groups. No effect of the fragmentation was found for ants, which may have the longest lag times because of long-lived colonies. However, relationships between abundance and the species' preferences for environmental factors affected by edge effects indicate that ant diversity too may be affected in the longer-term. Our results show the importance of considering different groups in conservation management in times of widespread fragmentation of landscapes. While species richness may respond slowly, changes in

  9. Changes in tree reproductive traits reduce functional diversity in a fragmented Atlantic forest landscape.

    Directory of Open Access Journals (Sweden)

    Luciana Coe Girão

    Full Text Available Functional diversity has been postulated to be critical for the maintenance of ecosystem functioning, but the way it can be disrupted by human-related disturbances remains poorly investigated. Here we test the hypothesis that habitat fragmentation changes the relative contribution of tree species within categories of reproductive traits (frequency of traits and reduces the functional diversity of tree assemblages. The study was carried out in an old and severely fragmented landscape of the Brazilian Atlantic forest. We used published information and field observations to obtain the frequency of tree species and individuals within 50 categories of reproductive traits (distributed in four major classes: pollination systems, floral biology, sexual systems, and reproductive systems in 10 fragments and 10 tracts of forest interior (control plots. As hypothesized, populations in fragments and control plots differed substantially in the representation of the four major classes of reproductive traits (more than 50% of the categories investigated. The most conspicuous differences were the lack of three pollination systems in fragments--pollination by birds, flies and non-flying mammals--and that fragments had a higher frequency of both species and individuals pollinated by generalist vectors. Hermaphroditic species predominate in both habitats, although their relative abundances were higher in fragments. On the contrary, self-incompatible species were underrepresented in fragments. Moreover, fragments showed lower functional diversity (H' scores for pollination systems (-30.3%, floral types (-23.6%, and floral sizes (-20.8% in comparison to control plots. In contrast to the overwhelming effect of fragmentation, patch and landscape metrics such as patch size and forest cover played a minor role on the frequency of traits. Our results suggest that habitat fragmentation promotes a marked shift in the relative abundance of tree reproductive traits and

  10. Progress report 1983-1984 Reactor Chemistry Department

    International Nuclear Information System (INIS)

    1985-11-01

    Description of the activity developed by the Reactor Chemistry Department of the National Atomic Energy Commission during the period 1983-1984 in its four divisions: Chemical Control; Moderator and Refrigerant Chemistry; Radiation Chemistry and Nuclear Power Plant's Service. A list of the publications made by the personnel during this period is also included. (M.E.L.) [es

  11. Using quantum chemistry muscle to flex massive systems: How to respond to something perturbing

    Energy Technology Data Exchange (ETDEWEB)

    Bertoni, Colleen [Iowa State Univ., Ames, IA (United States)

    2016-12-17

    Computational chemistry uses the theoretical advances of quantum mechanics and the algorithmic and hardware advances of computer science to give insight into chemical problems. It is currently possible to do highly accurate quantum chemistry calculations, but the most accurate methods are very computationally expensive. Thus it is only feasible to do highly accurate calculations on small molecules, since typically more computationally efficient methods are also less accurate. The overall goal of my dissertation work has been to try to decrease the computational expense of calculations without decreasing the accuracy. In particular, my dissertation work focuses on fragmentation methods, intermolecular interactions methods, analytic gradients, and taking advantage of new hardware.

  12. Progress report 1985-1986 Reactor Chemistry Department

    International Nuclear Information System (INIS)

    1987-12-01

    The report of the activities performed by the Reactor Chemistry Department of the National Atomic Energy Commission, during the period 1985-1986, covers works of investigation, development and service related to the Argentine Nuclear Power Plants. The main subjects are the experimental and theoretical studies about physical chemistry and chemistry control at the moderators and heat transport system of the nuclear power plants. The more relevant topics are related to: 1: Behaviour of gases, electrolites and other additives for nuclear power plants, at high temperature and pressure; 2: Ionic exchangers of nuclear degree; 3: Electrochemistry studies connected with the constitutive materials' corrosion and with the nuclear power plants decontamination processes; 4: Behaviour of suspensions and colloids in nuclear power plants; 5: Use of new additives for chemistry control of the oxides which are in the circuits of nuclear power plants; 6: Research methods that allow to check reactor's control quality; 7: Study of the radiolytic behaviour of nuclear reactor's solutions. (M.E.L.) [es

  13. Luciferase assay to study the activity of a cloned promoter DNA fragment.

    Science.gov (United States)

    Solberg, Nina; Krauss, Stefan

    2013-01-01

    Luciferase based assays have become an invaluable tool for the analysis of cloned promoter DNA fragments, both for verifying the ability of a potential promoter fragment to drive the expression of a luciferase reporter gene in various cellular contexts, and for dissecting binding elements in the promoter. Here, we describe the use of the Dual-Luciferase(®) Reporter Assay System created by Promega (Promega Corporation, Wisconsin, USA) to study the cloned 6.7 kilobases (kb) mouse (m) Tcf3 promoter DNA fragment in mouse embryonic derived neural stem cells (NSC). In this system, the expression of the firefly luciferase driven by the cloned mTcf3 promoter DNA fragment (including transcription initiation sites) is correlated with a co-transfected control reporter expressing Renilla luciferase from the herpes simplex virus (HSV) thymidine kinase promoter. Using an internal control reporter allows to normalize the activity of the experimental reporter to the internal control, which minimizes experimental variability.

  14. Reinventing Chemistry

    OpenAIRE

    Whitesides, George McClelland

    2015-01-01

    Chemistry is in a period of change, from an era focused on molecules and reactions, to one in which manipulations of systems of molecules and reactions will be essential parts of controlling larger systems. This Essay traces paths from the past to possible futures.

  15. Heart Rate Fragmentation: A Symbolic Dynamical Approach

    Directory of Open Access Journals (Sweden)

    Madalena D. Costa

    2017-11-01

    Full Text Available Background: We recently introduced the concept of heart rate fragmentation along with a set of metrics for its quantification. The term was coined to refer to an increase in the percentage of changes in heart rate acceleration sign, a dynamical marker of a type of anomalous variability. The effort was motivated by the observation that fragmentation, which is consistent with the breakdown of the neuroautonomic-electrophysiologic control system of the sino-atrial node, could confound traditional short-term analysis of heart rate variability.Objective: The objectives of this study were to: (1 introduce a symbolic dynamical approach to the problem of quantifying heart rate fragmentation; (2 evaluate how the distribution of the different dynamical patterns (“words” varied with the participants' age in a group of healthy subjects and patients with coronary artery disease (CAD; and (3 quantify the differences in the fragmentation patterns between the two sample populations.Methods: The symbolic dynamical method employed here was based on a ternary map of the increment NN interval time series and on the analysis of the relative frequency of symbolic sequences (words with a pre-defined set of features. We analyzed annotated, open-access Holter databases of healthy subjects and patients with CAD, provided by the University of Rochester Telemetric and Holter ECG Warehouse (THEW.Results: The degree of fragmentation was significantly higher in older individuals than in their younger counterparts. However, the fragmentation patterns were different in the two sample populations. In healthy subjects, older age was significantly associated with a higher percentage of transitions from acceleration/deceleration to zero acceleration and vice versa (termed “soft” inflection points. In patients with CAD, older age was also significantly associated with higher percentages of frank reversals in heart rate acceleration (transitions from acceleration to

  16. PWR secondary water chemistry guidelines

    International Nuclear Information System (INIS)

    Bell, M.J.; Blomgren, J.C.; Fackelmann, J.M.

    1982-10-01

    Steam generators in pressurized water reactor (PWR) nuclear power plants have experienced tubing degradation by a variety of corrosion-related mechanisms which depend directly on secondary water chemistry. As a result of this experience, the Steam Generator Owners Group and EPRI have sponsored a major program to provide solutions to PWR steam generator problems. This report, PWR Secondary Water Chemistry Guidelines, in addition to presenting justification for water chemistry control parameters, discusses available analytical methods, data management and surveillance, and the management philosophy required to successfully implement the guidelines

  17. Controlling nonspecific protein adsorption in a plug-based microfluidic system by controlling interfacial chemistry using fluorous-phase surfactants.

    Science.gov (United States)

    Roach, L Spencer; Song, Helen; Ismagilov, Rustem F

    2005-02-01

    Control of surface chemistry and protein adsorption is important for using microfluidic devices for biochemical analysis and high-throughput screening assays. This paper describes the control of protein adsorption at the liquid-liquid interface in a plug-based microfluidic system. The microfluidic system uses multiphase flows of immiscible fluorous and aqueous fluids to form plugs, which are aqueous droplets that are completely surrounded by fluorocarbon oil and do not come into direct contact with the hydrophobic surface of the microchannel. Protein adsorption at the aqueous-fluorous interface was controlled by using surfactants that were soluble in fluorocarbon oil but insoluble in aqueous solutions. Three perfluorinated alkane surfactants capped with different functional groups were used: a carboxylic acid, an alcohol, and a triethylene glycol group that was synthesized from commercially available materials. Using complementary methods of analysis, adsorption was characterized for several proteins (bovine serum albumin (BSA) and fibrinogen), including enzymes (ribonuclease A (RNase A) and alkaline phosphatase). These complementary methods involved characterizing adsorption in microliter-sized droplets by drop tensiometry and in nanoliter plugs by fluorescence microscopy and kinetic measurements of enzyme catalysis. The oligoethylene glycol-capped surfactant prevented protein adsorption in all cases. Adsorption of proteins to the carboxylic acid-capped surfactant in nanoliter plugs could be described by using the Langmuir model and tensiometry results for microliter drops. The microfluidic system was fabricated using rapid prototyping in poly(dimethylsiloxane) (PDMS). Black PDMS microfluidic devices, fabricated by curing a suspension of charcoal in PDMS, were used to measure the changes in fluorescence intensity more sensitively. This system will be useful for microfluidic bioassays, enzymatic kinetics, and protein crystallization, because it does not require

  18. Nuclear fragmentation

    International Nuclear Information System (INIS)

    Chung, K.C.

    1989-01-01

    An introduction to nuclear fragmentation, with emphasis in percolation ideas, is presented. The main theoretical models are discussed and as an application, the uniform expansion approximation is presented and the statistical multifragmentation model is used to calculate the fragment energy spectra. (L.C.)

  19. Oxidative stress induces mitochondrial fragmentation in frataxin-deficient cells

    Energy Technology Data Exchange (ETDEWEB)

    Lefevre, Sophie [Mitochondria, Metals and Oxidative Stress Laboratory, Institut Jacques Monod, CNRS-Universite Paris-Diderot, Sorbonne Paris Cite, 15 rue Helene Brion, 75205 Paris cedex 13 (France); ED515 UPMC, 4 place Jussieu 75005 Paris (France); Sliwa, Dominika [Mitochondria, Metals and Oxidative Stress Laboratory, Institut Jacques Monod, CNRS-Universite Paris-Diderot, Sorbonne Paris Cite, 15 rue Helene Brion, 75205 Paris cedex 13 (France); Rustin, Pierre [Inserm, U676, Physiopathology and Therapy of Mitochondrial Disease Laboratory, 75019 Paris (France); Universite Paris-Diderot, Faculte de Medecine Denis Diderot, IFR02 Paris (France); Camadro, Jean-Michel [Mitochondria, Metals and Oxidative Stress Laboratory, Institut Jacques Monod, CNRS-Universite Paris-Diderot, Sorbonne Paris Cite, 15 rue Helene Brion, 75205 Paris cedex 13 (France); Santos, Renata, E-mail: santos.renata@ijm.univ-paris-diderot.fr [Mitochondria, Metals and Oxidative Stress Laboratory, Institut Jacques Monod, CNRS-Universite Paris-Diderot, Sorbonne Paris Cite, 15 rue Helene Brion, 75205 Paris cedex 13 (France)

    2012-02-10

    Highlights: Black-Right-Pointing-Pointer Yeast frataxin-deficiency leads to increased proportion of fragmented mitochondria. Black-Right-Pointing-Pointer Oxidative stress induces complete mitochondrial fragmentation in {Delta}yfh1 cells. Black-Right-Pointing-Pointer Oxidative stress increases mitochondrial fragmentation in patient fibroblasts. Black-Right-Pointing-Pointer Inhibition of mitochondrial fission in {Delta}yfh1 induces oxidative stress resistance. -- Abstract: Friedreich ataxia (FA) is the most common recessive neurodegenerative disease. It is caused by deficiency in mitochondrial frataxin, which participates in iron-sulfur cluster assembly. Yeast cells lacking frataxin ({Delta}yfh1 mutant) showed an increased proportion of fragmented mitochondria compared to wild-type. In addition, oxidative stress induced complete fragmentation of mitochondria in {Delta}yfh1 cells. Genetically controlled inhibition of mitochondrial fission in these cells led to increased resistance to oxidative stress. Here we present evidence that in yeast frataxin-deficiency interferes with mitochondrial dynamics, which might therefore be relevant for the pathophysiology of FA.

  20. Current status of regulatory aspects relating to water chemistry in Japanese NPPs

    International Nuclear Information System (INIS)

    Sato, Masatoshi

    2014-01-01

    In nuclear power plants, water chemistry of cooling water is carefully monitored and controlled to keep integrity of structures, systems and components, and to reduce occupational radiation exposures. As increasing demand for advanced application of light water cooled reactors, water chemistry control plays more important roles on plant reliability. The road maps on R and D for water chemistry of nuclear power systems have been proposed along with promotion of R and D related water chemistry in Japan. In academic and engineering societies, non-governmental standards for water chemistry are going to be established. In the present paper, recent trends of water chemistry in Japan have been surveyed. The effects of water chemistry on plant safety and radiation exposures have been discussed. In addition, possible contributions of regulation regarding water chemistry control have been confirmed. Major water chemistry regulatory aspects relating to reactor safety and radiation safety are also outlined in this paper. (author)

  1. Controls of Ca/Mg/Fe activity ratios in pore water chemistry models of the Callovian-Oxfordian clay formation

    International Nuclear Information System (INIS)

    Lerouge, C.; Grangeon, S.; Wille, G.; Flehoc, C.; Gailhanou, H.; Gaucher, E.C.; Tournassat, C.; Vinsot, A.; Made, B.; Altmann, S.

    2013-01-01

    In the pore water chemistry model of the Callovian-Oxfordian clay formation, the divalent cations Ca, Mg, and Fe are controlled by equilibrium reactions with pure carbonates: calcite for Ca, dolomite for Mg, and siderite for Fe. Results of a petrological study and computing of the Ca/Mg and Ca/Fe activity ratios based on natural pore water chemistry provide evidence that equilibrium with pure calcite and pure dolomite is a reasonable assumption for undisturbed pore waters; on the other hand, siderite cannot be considered at equilibrium with pore waters at the formation scale. (authors)

  2. Controls of Ca/Mg/Fe activity ratios in pore water chemistry models of the Callovian-Oxfordian clay formation

    Energy Technology Data Exchange (ETDEWEB)

    Lerouge, C.; Grangeon, S.; Wille, G.; Flehoc, C.; Gailhanou, H.; Gaucher, E.C.; Tournassat, C. [BRGM av. Claude Guillemin BP6009 45060 Orleans cedex 2 (France); Vinsot, A. [ANDRA Meuse/Haute-Marne Underground research Laboratory (URL), RD 960, 55290 Bure (France); Made, B.; Altmann, S. [ANDRA - Parc de la Croix Blanche, 1-7 rue Jean Monnet, 92298 Chatenay-Malabry Cedex (France)

    2013-07-01

    In the pore water chemistry model of the Callovian-Oxfordian clay formation, the divalent cations Ca, Mg, and Fe are controlled by equilibrium reactions with pure carbonates: calcite for Ca, dolomite for Mg, and siderite for Fe. Results of a petrological study and computing of the Ca/Mg and Ca/Fe activity ratios based on natural pore water chemistry provide evidence that equilibrium with pure calcite and pure dolomite is a reasonable assumption for undisturbed pore waters; on the other hand, siderite cannot be considered at equilibrium with pore waters at the formation scale. (authors)

  3. Natural Pathogen Control Chemistry to Replace Toxic Treatment of Microbes and Biofilm in Cooling Towers

    Science.gov (United States)

    Brouse, Lon; Brouse, Richard; Brouse, Daniel

    2017-01-01

    Application of toxic antibacterial agents is considered necessary to control prevalent fresh water microorganisms that grow in evaporative cooling water systems, but can adversely affect the environment and human health. However, natural antibacterial water chemistry has been applied in industrial cooling water systems for over 10 years to inhibit microorganisms with excellent results. The water chemistry method concentrates natural minerals in highly-softened water to produce elevated pH and dissolved solids, while maintaining low calcium and magnesium content. The method provides further benefits in water conservation, and generates a small volume of non-toxic natural salt concentrate for cost efficient separation and disposal if required. This report describes the antimicrobial effects of these chemistry modifications in the cooling water environment and the resultant collective inhibition of microbes, biofilm, and pathogen growth. This article also presents a novel perspective of parasitic microbiome functional relationships, including “Trojan Protozoans” and biofilms, and the function of polyvalent metal ions in the formation and inhibition of biofilms. Reducing global dependence on toxic antibacterial agents discharged to the environment is an emerging concern due to their impact on the natural microbiome, plants, animals and humans. Concurrently, scientists have concluded that discharge of antibacterial agents plays a key role in development of pathogen resistance to antimicrobials as well as antibiotics. Use of natural antibacterial chemistry can play a key role in managing the cooling water environment in a more ecologically sustainable manner. PMID:28420074

  4. String fragmentation; La fragmentation des cordes

    Energy Technology Data Exchange (ETDEWEB)

    Drescher, H.J.; Werner, K. [Laboratoire de Physique Subatomique et des Technologies Associees - SUBATECH, Centre National de la Recherche Scientifique, 44 - Nantes (France)

    1997-10-01

    The classical string model is used in VENUS as a fragmentation model. For the soft domain simple 2-parton strings were sufficient, whereas for higher energies up to LHC, the perturbative regime of the QCD gives additional soft gluons, which are mapped on the string as so called kinks, energy singularities between the leading partons. The kinky string model is chosen to handle fragmentation of these strings by application of the Lorentz invariant area law. The `kinky strings` model, corresponding to the perturbative gluons coming from pQCD, takes into consideration this effect by treating the partons and gluons on the same footing. The decay law is always the Artru-Menessier area law which is the most realistic since it is invariant to the Lorentz and gauge transformations. For low mass strings a manipulation of the rupture point is necessary if the string corresponds already to an elementary particle determined by the mass and the flavor content. By means of the fragmentation model it will be possible to simulate the data from future experiments at LHC and RHIC 3 refs.

  5. Flash chemistry: flow chemistry that cannot be done in batch.

    Science.gov (United States)

    Yoshida, Jun-ichi; Takahashi, Yusuke; Nagaki, Aiichiro

    2013-11-04

    Flash chemistry based on high-resolution reaction time control using flow microreactors enables chemical reactions that cannot be done in batch and serves as a powerful tool for laboratory synthesis of organic compounds and for production in chemical and pharmaceutical industries.

  6. Univalents and fragments in the meiosis of mammals

    International Nuclear Information System (INIS)

    Vyglenov, A.

    1987-01-01

    The manifestation of univalents and fragments in spermatocytes in diakinese-metaphase was studied on mice, rats, Syrian hamsters and rabbits irradiated with various dose rates. It was established that the incidence of the univalents resulting from the separation of the XY and autosomic bivalents and of the fragments did not depend on the dose rate and there were no differences between the control and the irradiated animals. A species specificity was found in the manifestation of the gonosomic and to some extent of the autosomic univalents. To a certain extent the differences in the incidence of the autosomic univalents and particularly of the fragments most probably were a consequence of the various measuring methods. In comparative aspect, the investigated mammals rank as follows: with the lowest incidence of univalents and fragments was the macaque-rhesus, with higher was the rat, followed by the Syrian hamster and with very high - the mouse and rabbit

  7. Analytical and experimental evaluation of a proposed self-forging fragment munition

    International Nuclear Information System (INIS)

    Tuft, D.B.; Folsom, E.N.

    1982-01-01

    Analytical and experimental tools have been used to study the formation of a proposed self-forging fragment projectile. The primary objective of this study is the determination of the interior and exterior shape of the fully formed fragment, and to determine if the fragment tumbles in flight. In addition, it is of interest to compare computer predictions to experimental results. An experiment was performed using high speed photography and high-energy flash x-ray radiography to study liner and case motion and projectile formation. Fabrication and assembly tolerances were closely controlled in an effort to eliminate tolerances as a possible source of fragment instability. X-ray film-density contours were analyzed to determine the fully formed fragment interior and exterior shape. Down-range yaw screens showed fragment tumbling in flight. The computed fragment shape was compared to experimental results and it was found that a retaining ring in the computational model near the liner periphery had a significant effect on the final computed fragment shape. With the retaining ring in the computational model and full two-way sliding between all material interfaces, the final computed fragment showed very good agreement with the experiment on both exterior and interior shapes

  8. Fragment-based discovery of potent inhibitors of the anti-apoptotic MCL-1 protein.

    Science.gov (United States)

    Petros, Andrew M; Swann, Steven L; Song, Danying; Swinger, Kerren; Park, Chang; Zhang, Haichao; Wendt, Michael D; Kunzer, Aaron R; Souers, Andrew J; Sun, Chaohong

    2014-03-15

    Apoptosis is regulated by the BCL-2 family of proteins, which is comprised of both pro-death and pro-survival members. Evasion of apoptosis is a hallmark of malignant cells. One way in which cancer cells achieve this evasion is thru overexpression of the pro-survival members of the BCL-2 family. Overexpression of MCL-1, a pro-survival protein, has been shown to be a resistance factor for Navitoclax, a potent inhibitor of BCL-2 and BCL-XL. Here we describe the use of fragment screening methods and structural biology to drive the discovery of novel MCL-1 inhibitors from two distinct structural classes. Specifically, cores derived from a biphenyl sulfonamide and salicylic acid were uncovered in an NMR-based fragment screen and elaborated using high throughput analog synthesis. This culminated in the discovery of selective and potent inhibitors of MCL-1 that may serve as promising leads for medicinal chemistry optimization efforts. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Mojibake - The rehearsal of word fragments in verbal recall.

    Science.gov (United States)

    Lange-Küttner, Christiane; Sykorova, Eva

    2015-01-01

    Theories of verbal rehearsal usually assume that whole words are being rehearsed. However, words consist of letter sequences, or syllables, or word onset-vowel-coda, amongst many other conceptualizations of word structure. A more general term is the 'grain size' of word units (Ziegler and Goswami, 2005). In the current study, a new method measured the quantitative percentage of correctly remembered word structure. The amount of letters in the correct letter sequence as per cent of word length was calculated, disregarding missing or added letters. A forced rehearsal was tested by repeating each memory list four times. We tested low frequency (LF) English words versus geographical (UK) town names to control for content. We also tested unfamiliar international (INT) non-words and names of international (INT) European towns to control for familiarity. An immediate versus distributed repetition was tested with a between-subject design. Participants responded with word fragments in their written recall especially when they had to remember unfamiliar words. While memory of whole words was sensitive to content, presentation distribution and individual sex and language differences, recall of word fragments was not. There was no trade-off between memory of word fragments with whole word recall during the repetition, instead also word fragments significantly increased. Moreover, while whole word responses correlated with each other during repetition, and word fragment responses correlated with each other during repetition, these two types of word recall responses were not correlated with each other. Thus there may be a lower layer consisting of free, sparse word fragments and an upper layer that consists of language-specific, orthographically and semantically constrained words.

  10. Primary water chemistry control at units of Paks Nuclear Power Plant

    International Nuclear Information System (INIS)

    Schunk, J.; Patek, G.; Pinter, T.; Tilky, P.; Doma, A.; Osz, J.

    2010-01-01

    The primary water chemistry of the four identical units of Paks Nuclear Power Plant has been developed based on Western-type PWR units, taking into consideration some Soviet-Russian modifications. The political changes in 90s have also influenced the water chemistry specifications and directions. At PWR units the transition operational modes have been developed while in case of VVER units - in lack of central uniform regulation - this question has become the competence and responsibility of each individual plant. This problem has resulted in separate water chemistry developments with a considerable time delay. The needs for life-time extensions all over the World have made the development of start-up and shut-down chemistry procedures extremely important, since they considerably influence the long term and safe operation of plants. The uniformly structured limit value system, the principles applied for the system development, and the logic schemes for actions to be taken are discussed in the paper, both for normal operation and transition modes. (author)

  11. Primary Water Chemistry Control at Units of Paks Nuclear Power Plant

    Energy Technology Data Exchange (ETDEWEB)

    Schunk, J.; Pinter, G. Patek T.; Tilky, P.; Doma, A. [Paks Nuclear Power Plant Co. Ltd., Paks (Hungary); Osz, J. [Budapest University of Technology and Economics, Budapest (Hungary)

    2013-03-15

    The primary water chemistry of the four identical units of Paks Nuclear Power Plant has been developed based on Western type PWR units, taking into consideration some Russian modifications. The political changes in the 1990s have also influenced the water chemistry specifications and directions. At PWR units the transition operational modes have been developed while in case of WWER units - in lack of central uniform regulation - this question has become the competence and responsibility of each individual plant. This problem has resulted in separate water chemistry developments with a considerable time delay. The need for lifetime extensions worldwide has made the development of startup and shutdown chemistry procedures extremely important, since they considerably influence the long term and safe operation of plants. The uniformly structured limit value system, the principles applied for the system development, and the logic schemes for actions to be taken are discussed in the paper, both for normal operation and transition modes. (author)

  12. PWR secondary water chemistry diagnostic system

    International Nuclear Information System (INIS)

    Miyazaki, S.; Hattori, T.; Yamauchi, S.; Kato, A.; Suganuma, S.; Yoshikawa, T.

    1989-01-01

    Water chemistry control is one of the most important tasks in order to maintain the reliability of plant equipments and extend operating life of the plant. We developed an advanced water chemistry management system which is able to monitor and diagnose secondary water chemistry. A prototype system had been installed at one plant in Japan since Nov. 1986 in order to evaluate system performance and man-machine interface. The diagnosis system has been successfully tested off line using synthesized plant data for various cases. We are continuing to improve the applicability and develop new technology which make it evaluate steam generator crevice chemistry. (author)

  13. BWR and PWR chemistry operating experience and perspectives

    International Nuclear Information System (INIS)

    Fruzzetti, K.; Garcia, S.; Lynch, N.; Reid, R.

    2014-01-01

    It is well recognized that proper control of water chemistry plays a critical role in ensuring the safe and reliable operation of Boiling Water Reactors (BWRs) and Pressurized Water Reactors (PWRs). State-of-the-art water chemistry programs reduce general and localized corrosion of reactor coolant system, steam cycle equipment, and fuel cladding materials; ensure continued integrity of cycle components; and reduce radiation fields. Once a particular nuclear plant component has been installed or plant system constructed, proper water chemistry provides a global tool to mitigate materials degradation problems, thereby reducing the need for costly repairs or replacements. Recognizing the importance of proper chemistry control and the value in understanding the relationship between chemistry guidance and actual operating experience, EPRI continues to collect, monitor, and evaluate operating data from BWRs and PWRs around the world. More than 900 cycles of valuable BWR and PWR operating chemistry data has been collected, including online, startup and shutdown chemistry data over more than 10 years (> 20 years for BWRs). This paper will provide an overview of current trends in BWR and PWR chemistry, focusing on plants in the U.S.. Important chemistry parameters will be highlighted and discussed in the context of the EPRI Water Chemistry Guidelines requirements (i.e., those parameters considered to be of key importance as related to the major goals identified in the EPRI Guidelines: materials integrity; fuel integrity; and minimizing plant radiation fields). Perspectives will be provided in light of recent industry initiatives and changes in the EPRI BWR and PWR Water Chemistry Guidelines. (author)

  14. Fission fragment angular momentum

    International Nuclear Information System (INIS)

    Frenne, D. De

    1991-01-01

    Most of the energy released in fission is converted into translational kinetic energy of the fragments. The remaining excitation energy will be distributed among neutrons and gammas. An important parameter characterizing the scission configuration is the primary angular momentum of the nascent fragments. Neutron emission is not expected to decrease the spin of the fragments by more than one unit of angular momentum and is as such of less importance in the determination of the initial fragment spins. Gamma emission is a suitable tool in studying initial fragment spins because the emission time, number, energy, and multipolarity of the gammas strongly depend on the value of the primary angular momentum. The main conclusions of experiments on gamma emission were that the initial angular momentum of the fragments is large compared to the ground state spin and oriented perpendicular to the fission axis. Most of the recent information concerning initial fragment spin distributions comes from the measurement of isomeric ratios for isomeric pairs produced in fission. Although in nearly every mass chain isomers are known, only a small number are suitable for initial fission fragment spin studies. Yield and half-life considerations strongly limit the number of candidates. This has the advantage that the behavior of a specific isomeric pair can be investigated for a number of fissioning systems at different excitation energies of the fragments and fissioning nuclei. Because most of the recent information on primary angular momenta comes from measurements of isomeric ratios, the global deexcitation process of the fragments and the calculation of the initial fragment spin distribution from measured isomeric ratios are discussed here. The most important results on primary angular momentum determinations are reviewed and some theoretical approaches are given. 45 refs., 7 figs., 2 tabs

  15. Loop capabilities in Rez for water chemistry and corrosion control of cladding and in-core components

    International Nuclear Information System (INIS)

    Kysela, J.; Zmitko, M.; Srank, J.; Vsolak, R.

    1999-01-01

    Main characteristics of LVR-15 research reactor and its irradiation facilities are presented. For testing of cladding, internals and RPV materials specialised loop are used. There are now five high pressure loops modelling PWR, WWER or BWR water environment and chemistry. Loops can be connected with instrumented in-pile channels enable slow strain rate testing, 1CT or 2CT specimens loading and electrically heated rods exposition. Reactor dosimetry including neutronic parameters measurements and calculations and mock-up experiments are used. Water chemistry control involves gas (O 2 , H 2 ) dosing system, Orbisphere H 2 /O 2 measurement, electrochemical potential (ECP) measurements and specialised analytical chemistry laboratory. For cladding corrosion studies in-pile channels with four electrically heated rods with heat flux up to 100 W/cm 2 , void fraction 5 % at the outlet, inlet temperature 320 deg. C and flow velocity 3 m/s were development and tested. For corrosion layer investigation there is eddy current measurements and PIE techniques which use crud thickness measurement, chemical analyses of the crud, optical metallography, hydrogen analysis, SEM and TEM. (author)

  16. Molecular Chemistry and Engineering of Boron-Modified Polyorganosilazanes as New Processable and Functional SiBCN Precursors.

    Science.gov (United States)

    Viard, Antoine; Fonblanc, Diane; Schmidt, Marion; Lale, Abhijeet; Salameh, Chrystelle; Soleilhavoup, Anne; Wynn, Mélanie; Champagne, Philippe; Cerneaux, Sophie; Babonneau, Florence; Chollon, Georges; Rossignol, Fabrice; Gervais, Christel; Bernard, Samuel

    2017-07-06

    A series of boron-modified polyorganosilazanes was synthesized from a poly(vinylmethyl-co-methyl)silazane and controlled amounts of borane dimethyl sulfide. The role of the chemistry behind their synthesis has been studied in detail by using solid-state NMR spectroscopy, FTIR spectroscopy, and elemental analysis. The intimate relationship between the chemistry and the processability of these polymers is discussed. Polymers with low boron contents displayed appropriate requirements for facile processing in solution, such as impregnation of host carbon materials, which resulted in the design of mesoporous monoliths with a high specific surface area after pyrolysis. Polymers with high boron content are more appropriate for solid-state processing to design mechanically robust monolith-type macroporous and dense structures after pyrolysis. Boron acts as a crosslinking element, which offers the possibility to extend the processability of polyorganosilazanes and suppress the distillation of oligomeric fragments in the low-temperature region of their thermal decomposition (i.e., pyrolysis) at 1000 °C under nitrogen. Polymers with controlled and high ceramic yields were generated. We provide a comprehensive mechanistic study of the two-step thermal decomposition based on a combination of thermogravimetric experiments coupled with elemental analysis, solid-state NMR spectroscopy, and FTIR spectroscopy. Selected characterization tools allowed the investigation of specific properties of the monolith-type SiBCN materials. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Synthesis of hydrogel via click chemistry for DNA electrophoresis.

    Science.gov (United States)

    Finetti, Chiara; Sola, Laura; Elliott, Jim; Chiari, Marcella

    2017-09-01

    This work introduces a novel sieving gel for DNA electrophoresis using a classical click chemistry reaction, the copper (I)-catalyzed azide-alkyne cycloaddition (CuAAC), to cross-link functional polymer chains. The efficiency of this reaction provides, under mild conditions, hydrogels with near-ideal network connectivity and improved physical properties. Hydrogel formation via click chemistry condensation of functional polymers does not involve the use of toxic monomers and UV initiation. The performance of the new hydrogel in the separation of double stranded DNA fragments was evaluated in the 2200 TapeStation system, an analytical platform, recently introduced by Agilent that combines the advantages of CE in terms of miniaturization and automation with the simplicity of use of slab gel electrophoresis. The click gel enables addition of florescent dyes prior to electrophoresis with considerable improvement of resolution and separation efficiency over conventional cross-linked polyacrylamide gels. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. The BioFragment Database (BFDb): An open-data platform for computational chemistry analysis of noncovalent interactions

    Science.gov (United States)

    Burns, Lori A.; Faver, John C.; Zheng, Zheng; Marshall, Michael S.; Smith, Daniel G. A.; Vanommeslaeghe, Kenno; MacKerell, Alexander D.; Merz, Kenneth M.; Sherrill, C. David

    2017-10-01

    Accurate potential energy models are necessary for reliable atomistic simulations of chemical phenomena. In the realm of biomolecular modeling, large systems like proteins comprise very many noncovalent interactions (NCIs) that can contribute to the protein's stability and structure. This work presents two high-quality chemical databases of common fragment interactions in biomolecular systems as extracted from high-resolution Protein DataBank crystal structures: 3380 sidechain-sidechain interactions and 100 backbone-backbone interactions that inaugurate the BioFragment Database (BFDb). Absolute interaction energies are generated with a computationally tractable explicitly correlated coupled cluster with perturbative triples [CCSD(T)-F12] "silver standard" (0.05 kcal/mol average error) for NCI that demands only a fraction of the cost of the conventional "gold standard," CCSD(T) at the complete basis set limit. By sampling extensively from biological environments, BFDb spans the natural diversity of protein NCI motifs and orientations. In addition to supplying a thorough assessment for lower scaling force-field (2), semi-empirical (3), density functional (244), and wavefunction (45) methods (comprising >1M interaction energies), BFDb provides interactive tools for running and manipulating the resulting large datasets and offers a valuable resource for potential energy model development and validation.

  19. Azimuthal Anisotropies in Nuclear Fragmentation

    International Nuclear Information System (INIS)

    Dabrowska, A.; Szarska, M.; Trzupek, A.; Wolter, W.; Wosiek, B.

    2002-01-01

    The directed and elliptic flow of fragments emitted from the excited projectile nuclei has been observed for 158 AGeV Pb collisions with the lead and plastic targets. For comparison the flow analysis has been performed for 10.6 AGeV Au collisions with the emulsion target. The strong directed flow of heaviest fragments is found. Light fragments exhibit directed flow opposite to that of heavy fragments. The elliptic flow for all multiply charged fragments is positive and increases with the charge of the fragment. The observed flow patterns in the fragmentation of the projectile nucleus are practically independent of the mass of the target nucleus and the collision energy. Emission of fragments in nuclear multifragmentation shows similar, although weaker, flow effects. (author)

  20. Water chemistry experiences with VVERs at Kudankulam

    International Nuclear Information System (INIS)

    Rout, D.; Upadhyaya, T.C.; Ravindranath; Selvinayagam, P.; Sundar, R.S.

    2015-01-01

    Kudankulam Nuclear Power Project - 1 and 2 (Kudankulam NPP - 1 and 2) are pressurised water cooled VVERs of 1000 MWe each. Kudankulam NPP Unit - 1 is presently on its first cycle of operation and Kudankulam NPP Unit - 2 is on the advanced stage of commissioning with the successful completion of hot run related Functional tests. Water Chemistry aspects during various phases of commissioning of Kudankulam NPP Unit - 1 such as Hot Run, Boric acid flushing, initial fuel Loading (IFL), First approach to Criticality (FAC) are discussed. The main objectives of the use of controlled primary water chemistry programme during the hot functional tests are reviewed. The importance of the relevant water chemistry parameters were ensured to have the quality of the passive layer formed on the primary coolant system surfaces. The operational experiences during the 1 st cycle of operation of primary water chemistry, radioactivity transport and build-up are presented. The operational experience of some VVER units in the field of the primary water chemistry, radioactivity transport and build-up are presented as a comparison to VVER at Kudankulam NPP. The effects of the initial passivated layer formed on metal surfaces during hot run, activated corrosion products levels in the primary coolant under controlled water chemistry regime and the contamination/radiation situation are discussed. This report also includes the water chemistry related issues of secondary water systems. (author)

  1. Nonlinear transient responses of beams and rings to impulse loading or fragment impact

    International Nuclear Information System (INIS)

    Witmer, E.A.; Stagliano, T.R.; Rodal, J.J.A.

    1977-01-01

    The present paper is concerned with a very limited part of the cited fragment threat; namely, fragments from high speed rotating machinery such as (1) aircraft engine rotors and (2) stationary power plant turbine rotors. Further, it is assumed that the structures intended to contain or control these fragments consist of initially-isotropic elastic-plastic metals. Certain potential containment/control (C/C) structures behave in a planar (or two-dimensional) fashion while other fragment-attacked C/C structures will undergo general three-dimensional deformations. Predictions for only the former category of fragment-attacked structures are discussed in the present paper. Pertinent experimental data discussed here on fragment-attacked structures include (a) steel-sphere impact data involving beam targets and (b) engine rotor fragment impact against a steel containment ring. In all of these cases large-deflection, elastic-plastic transient structural response occur. The governing equations employed are presented in the present analysis to predict the responses of protective (metal) structures to engine-rotor-fragment impact. The protective structure is intended either to contain or to deflect the attacking fragments away from important regions; large-deflection, elasic-plastic structural response is expected because these protective structures must have the least feasible weight. Concise geometric and assumed-displacement-field descriptions of the several types of finite elements to be utilized in subsequent examples are given, together with several categories of strain displacement relations. Both low- and higher-order elements are discussed

  2. Analysis of fission-fragment mass distribution within the quantum-mechanical fragmentation theory

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Pardeep; Kaur, Harjeet [Guru Nanak Dev University, Department of Physics, Amritsar (India)

    2016-11-15

    The fission-fragment mass distribution is analysed for the {sup 208}Pb({sup 18}O, f) reaction within the quantum-mechanical fragmentation theory (QMFT). The reaction potential has been calculated by taking the binding energies, Coulomb potential and proximity potential of all possible decay channels and a stationary Schroedinger equation has been solved numerically to calculate the fission-fragment yield. The overall results for mass distribution are compared with those obtained in experiment. Fine structure dips in yield, corresponding to fragment shell closures at Z = 50 and N=82, which are observed by Bogachev et al., are reproduced successfully in the present calculations. These calculations will help to estimate the formation probabilities of fission fragments and to understand many related phenomena occurring in the fission process. (orig.)

  3. Chemistry Programme for Water Cooled Nuclear Power Plants. Specific Safety Guide (Russian Edition)

    International Nuclear Information System (INIS)

    2014-01-01

    This publication provides guidance on establishing a high standard chemistry programme in accordance with plant safety policy and regulatory requirements. It will be useful to managers of operating organizations and other staff responsible for supporting or monitoring plant activities and for oversight of the plant chemistry programme, as well as to regulatory bodies. Contents: 1. Introduction; 2. Functions, responsibilities and interfaces; 3. Chemistry programme; 4. Chemistry control; 5. Chemistry aspects of radiation exposure optimization; 6. Chemistry surveillance; 7. Management of chemistry data; 8. Training and qualification; 9. Quality control of chemicals and other substances

  4. Third Chemistry Conference on Recent Trends in Chemistry

    International Nuclear Information System (INIS)

    Saeed, M.M.; Wheed, S.

    2011-01-01

    The third chemistry conference 2011 on recent trends in chemistry was held from October 17-19, 2001 at Islamabad, Pakistan. More than 65 papers and oral presentation. The scope of the conference was wide open and provides and opportunity for participation of broad spectrum of chemists. This forum provided a platform for the dissemination of the latest research followed by discussion pertaining to new trends in chemistry. This con fence covered different aspects of subjects including analytical chemistry, environmental chemistry, polymer chemistry, industrial chemistry, biochemistry and nano chemistry etc. (A.B.)

  5. Ammonia chemistry at SMART

    International Nuclear Information System (INIS)

    Na, J. W.; Seong, G. W.; Lee, E. H.; Kim, W. C.; Choi, B. S.; Kim, J. P.; Lee, D. J.

    1999-01-01

    Ammonia is used as the pH control agent of primary water at SMART (System-integrated Modular Advanced ReacTor). Some of this ammonia is decomposed to hydrogen and nitrogen by radiation in the reactor core. The produced hydrogen gas is used for the removal of dissolved oxygen in the coolant. Some of nitrogen gas in pressurizer is dissolved into the primary water. Because ammonia, hydrogen and nitrogen which is produced by ammonia radiolysis are exist in the coolant at SMART, ammonia chemistry at SMART is different with lithium-boron chemistry at commercial PWR. In this study, the pH characteristics of ammonia and the solubility characteristics of hydrogen and nytrogen were analyzed for the management of primary water chemistry at SMART

  6. Major ion chemistry of the Son River, India

    Indian Academy of Sciences (India)

    The chemistry of major ions in the surface water of the Son River was studied in detail to determine various source(s) and processes controlling its water chemistry, seasonal and spatial variations in water chemistry, dissolved fluxes and chemical denudation rate (CDR). The study shows that Ca2+, Mg2+ and HCO 3 − are ...

  7. Molecular dynamics for irradiation driven chemistry

    DEFF Research Database (Denmark)

    Sushko, Gennady B.; Solov'yov, Ilia A.; Solov'yov, Andrey V.

    2016-01-01

    A new molecular dynamics (MD) approach for computer simulations of irradiation driven chemical transformations of complex molecular systems is suggested. The approach is based on the fact that irradiation induced quantum transformations can often be treated as random, fast and local processes...... that describe the classical MD of complex molecular systems under irradiation. The proposed irradiation driven molecular dynamics (IDMD) methodology is designed for the molecular level description of the irradiation driven chemistry. The IDMD approach is implemented into the MBN Explorer software package...... involving small molecules or molecular fragments. We advocate that the quantum transformations, such as molecular bond breaks, creation and annihilation of dangling bonds, electronic charge redistributions, changes in molecular topologies, etc., could be incorporated locally into the molecular force fields...

  8. Humidity Effects on Fragmentation in Plasma-Based Ambient Ionization Sources.

    Science.gov (United States)

    Newsome, G Asher; Ackerman, Luke K; Johnson, Kevin J

    2016-01-01

    Post-plasma ambient desorption/ionization (ADI) sources are fundamentally dependent on surrounding water vapor to produce protonated analyte ions. There are two reports of humidity effects on ADI spectra. However, it is unclear whether humidity will affect all ADI sources and analytes, and by what mechanism humidity affects spectra. Flowing atmospheric pressure afterglow (FAPA) ionization and direct analysis in real time (DART) mass spectra of various surface-deposited and gas-phase analytes were acquired at ambient temperature and pressure across a range of observed humidity values. A controlled humidity enclosure around the ion source and mass spectrometer inlet was used to create programmed humidity and temperatures. The relative abundance and fragmentation of molecular adduct ions for several compounds consistently varied with changing ambient humidity and also were controlled with the humidity enclosure. For several compounds, increasing humidity decreased protonated molecule and other molecular adduct ion fragmentation in both FAPA and DART spectra. For others, humidity increased fragment ion ratios. The effects of humidity on molecular adduct ion fragmentation were caused by changes in the relative abundances of different reagent protonated water clusters and, thus, a change in the average difference in proton affinity between an analyte and the population of water clusters. Control of humidity in ambient post-plasma ion sources is needed to create spectral stability and reproducibility.

  9. Sodium-doping as a reference to study the influence of intracluster chemistry on the fragmentation of weakly-bound clusters upon vacuum ultraviolet photoionization

    OpenAIRE

    Litman Jessica H; Yoder Bruce L; Schläppi Bernhard; Signorell Ruth

    2012-01-01

    The fragmentation of methanol water dimethyl ether and acetic acid clusters upon photoionization with a single vacuum ultraviolet (VUV) photon of 10.1 eV 13.3 eV or 17.5 eV energy is studied with mass spectrometry. The sodium doping method is used as an independent approximate measure of the original cluster size distribution providing information on the degree of fragmentation upon VUV ionization. The experimental results show strong fragmentation for (CH3)2O and CH3CO2H clusters but minor f...

  10. Hypervelocity Impact Test Fragment Modeling: Modifications to the Fragment Rotation Analysis and Lightcurve Code

    Science.gov (United States)

    Gouge, Michael F.

    2011-01-01

    Hypervelocity impact tests on test satellites are performed by members of the orbital debris scientific community in order to understand and typify the on-orbit collision breakup process. By analysis of these test satellite fragments, the fragment size and mass distributions are derived and incorporated into various orbital debris models. These same fragments are currently being put to new use using emerging technologies. Digital models of these fragments are created using a laser scanner. A group of computer programs referred to as the Fragment Rotation Analysis and Lightcurve code uses these digital representations in a multitude of ways that describe, measure, and model on-orbit fragments and fragment behavior. The Dynamic Rotation subroutine generates all of the possible reflected intensities from a scanned fragment as if it were observed to rotate dynamically while in orbit about the Earth. This calls an additional subroutine that graphically displays the intensities and the resulting frequency of those intensities as a range of solar phase angles in a Probability Density Function plot. This document reports the additions and modifications to the subset of the Fragment Rotation Analysis and Lightcurve concerned with the Dynamic Rotation and Probability Density Function plotting subroutines.

  11. Fragment capture device

    Science.gov (United States)

    Payne, Lloyd R.; Cole, David L.

    2010-03-30

    A fragment capture device for use in explosive containment. The device comprises an assembly of at least two rows of bars positioned to eliminate line-of-sight trajectories between the generation point of fragments and a surrounding containment vessel or asset. The device comprises an array of at least two rows of bars, wherein each row is staggered with respect to the adjacent row, and wherein a lateral dimension of each bar and a relative position of each bar in combination provides blockage of a straight-line passage of a solid fragment through the adjacent rows of bars, wherein a generation point of the solid fragment is located within a cavity at least partially enclosed by the array of bars.

  12. Supramolecular chemistry-general principles and selected examples from anion recognition and metallosupramolecular chemistry.

    Science.gov (United States)

    Albrecht, Markus

    2007-12-01

    This review gives an introduction into supramolecular chemistry describing in the first part general principles, focusing on terms like noncovalent interaction, molecular recognition, self-assembly, and supramolecular function. In the second part those will be illustrated by simple examples from our laboratories. Supramolecular chemistry is the science that bridges the gap between the world of molecules and nanotechnology. In supramolecular chemistry noncovalent interactions occur between molecular building blocks, which by molecular recognition and self-assembly form (functional) supramolecular entities. It is also termed the "chemistry of the noncovalent bond." Molecular recognition is based on geometrical complementarity based on the "key-and-lock" principle with nonshape-dependent effects, e.g., solvatization, being also highly influential. Self-assembly leads to the formation of well-defined aggregates. Hereby the overall structure of the target ensemble is controlled by the symmetry features of the certain building blocks. Finally, the aggregates can possess special properties or supramolecular functions, which are only found in the ensemble but not in the participating molecules. This review gives an introduction on supramolecular chemistry and illustrates the fundamental principles by recent examples from our group.

  13. Optimizing the continuum of cycle chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Mathews, James A. [Electric Power Research Institute, Charlotte, NC (United States). Generation Sector, Steam and Cycle Chemistry

    2012-07-15

    In 2011 EPRI issued the fourth (4th) major revision to the cycle chemistry guidelines for fossil plants, re-combining the previously segregated ''treatment'' guidelines into a comprehensive document. As with each of the series of previous revisions, the 2011 updated guidelines focus on the optimization of chemistry practices for maintaining the availability, reliability, and economic performance of fossil power plants. A key element in the development and revision of the guidelines is extensive research conducted over the past fifty (50) plus years. Providing an understanding the elements of the power plant cycle and the interrelationships of the best chemistry practices are a basic tenet of the introductory chapters of the guidelines. The target values for each treatment practice and location in the cycle are discussed with specific emphasis on optimization and customization to achieve excellent corrosion protection and elimination of deposition and component damage and failure. The rationale for proper chemistry is presented; for example properly maintaining oxidizing potentials, impact of temperature on pH control, assuring alkaline (sodium) neutralization for controlling boiler corrosion, and other considerations. (orig.)

  14. Radiation chemistry

    International Nuclear Information System (INIS)

    Rodgers, F.; Rodgers, M.A.

    1987-01-01

    The contents of this book include: Interaction of ionizing radiation with matter; Primary products in radiation chemistry; Theoretical aspects of radiation chemistry; Theories of the solvated electron; The radiation chemistry of gases; Radiation chemistry of colloidal aggregates; Radiation chemistry of the alkali halides; Radiation chemistry of polymers; Radiation chemistry of biopolymers; Radiation processing and sterilization; and Compound index

  15. The water chemistry of CANDU PHW reactors

    International Nuclear Information System (INIS)

    LeSurf, J.E.

    1978-01-01

    This review will discuss the chemistry of the three major water circuits in a CANDU-PHW reactor, viz., the Primary Heat Transport (PHT) water, the moderator and the boiler water. An important consideration for the PHT chemistry is the control of corrosion and of the transport of corrosion products to minimize the growth of radiation fields. In new reactors the PHT will be allowed to boil, requiring reconsideration of the methods used to radiolytic oxygen and elevate the pH. Separation of the moderator from the PHT in the pressure-tubed CANDU design permits better optimization of the chemistry of each system, avoiding the compromises necessary when the same water serves both functions. Major objectives in moderator chemistry are to control (a) the radiolytic decomposition of D 2 0; (b) the concentration of soluble neutron poisons added to adjust reactivity; and (c) the chemistry of shutdown systems. The boiler water and its feed water are treated to avoid boiler tube corrosion, both during normal operation and when perturbations are caused to the feed by, for example, leaks in the condenser tubes which permit ingress of untreated condenser cooling water. Development of a system for automatic analysis and control of feed water to give rapid, reliable response to abnormal conditions is a novel feature which has been developed for incorporation in future CANDU-PHW reactors. (author)

  16. Fragmentation of molecular ions in slow electron collisions

    International Nuclear Information System (INIS)

    Novotny, Steffen

    2008-01-01

    The fragmentation of positively charged hydrogen molecular ions by the capture of slow electrons, the so called dissociative recombination (DR), has been investigated in storage ring experiments at the TSR, Heidelberg, where an unique twin-electron-beam arrangement was combined with high resolution fragment imaging detection. Provided with well directed cold electrons the fragmentation kinematics were measured down to meV collision energies where pronounced rovibrational Feshbach resonances appear in the DR cross section. For thermally excited HD + the fragmentation angle and the kinetic energy release were studied at variable precisely controlled electron collision energies on a dense energy grid from 10 to 80 meV. The anisotropy described for the first time by Legendre polynomials higher 2 nd order and the extracted rotational state contributions were found to vary on a likewise narrow energy scale as the rotationally averaged DR rate coefficient. Ro-vibrationally resolved DR experiments were performed on H 2 + produced in distinct internal excitations by a novel ion source. Both the low-energy DR rate as well as the fragmentation dynamics at selected resonances were measured individually in the lowest two vibrational and first three excited rotational states. State-specific DR rates and angular dependences are reported. (orig.)

  17. Fragmentation of molecular ions in slow electron collisions

    Energy Technology Data Exchange (ETDEWEB)

    Novotny, Steffen

    2008-06-25

    The fragmentation of positively charged hydrogen molecular ions by the capture of slow electrons, the so called dissociative recombination (DR), has been investigated in storage ring experiments at the TSR, Heidelberg, where an unique twin-electron-beam arrangement was combined with high resolution fragment imaging detection. Provided with well directed cold electrons the fragmentation kinematics were measured down to meV collision energies where pronounced rovibrational Feshbach resonances appear in the DR cross section. For thermally excited HD{sup +} the fragmentation angle and the kinetic energy release were studied at variable precisely controlled electron collision energies on a dense energy grid from 10 to 80 meV. The anisotropy described for the first time by Legendre polynomials higher 2{sup nd} order and the extracted rotational state contributions were found to vary on a likewise narrow energy scale as the rotationally averaged DR rate coefficient. Ro-vibrationally resolved DR experiments were performed on H{sub 2}{sup +} produced in distinct internal excitations by a novel ion source. Both the low-energy DR rate as well as the fragmentation dynamics at selected resonances were measured individually in the lowest two vibrational and first three excited rotational states. State-specific DR rates and angular dependences are reported. (orig.)

  18. Exact Solutions of Fragmentation Equations with General Fragmentation Rates and Separable Particles Distribution Kernels

    Directory of Open Access Journals (Sweden)

    S. C. Oukouomi Noutchie

    2014-01-01

    Full Text Available We make use of Laplace transform techniques and the method of characteristics to solve fragmentation equations explicitly. Our result is a breakthrough in the analysis of pure fragmentation equations as this is the first instance where an exact solution is provided for the fragmentation evolution equation with general fragmentation rates. This paper is the key for resolving most of the open problems in fragmentation theory including “shattering” and the sudden appearance of infinitely many particles in some systems with initial finite particles number.

  19. Land fragmentation and production diversification

    NARCIS (Netherlands)

    Ciaian, Pavel; Guri, Fatmir; Rajcaniova, Miroslava; Drabik, Dusan; Paloma, Sergio Gomez Y.

    2018-01-01

    We analyze the impact of land fragmentation on production diversification in rural Albania. Albania represents a particularly interesting case for studying land fragmentation as the fragmentation is a direct outcome of land reforms. The results indicate that land fragmentation is an important driver

  20. Influence of joint direction and position of explosive charge on fragmentation

    International Nuclear Information System (INIS)

    Hafsaoui, Abdellah; Talhi, Korichi

    2009-01-01

    Although researchers have realized varying degrees of success in small-scale physical in situ testing, most will agree that the greatest uncertainty stems from the uncontrollable field variables. Given the diverse nature of field conditions encountered, there exists no reliable and proven method of predicting fragmentation. Due to the lack of adequate field controls, it is unlikely that a universal physical model will ever be developed for all blasting. This paper presents the results of a test conducted at the Hadjar Essoud quarry to investigate the problems associated with the discontinuities in the rock, which are among the factors causing the reduction of the resistance of the rocks to the explosive. Nevertheless, the distance between the joints, their dip and strike, and the position of the detonator play a significant role in the final fragmentation of the rock. In this work, we studied the role of the abovementioned factors on models of limestone rock of 150 X 375 X 450 mm. Accurate measurement of blast, fragmentation is important in mining and quarrying operations, in monitoring blasts, and optimizing their design. We shall use the Kuznetsov-Rammler method to measure fragmentation. It shows great potential as a practical aid to predict and control the quality of the fragmented material in the Hadjar Essoud quarry. (author)

  1. Fragmentation processes in nuclear reactions

    International Nuclear Information System (INIS)

    Legrain, R.

    1984-08-01

    Projectile and nuclear fragmentation are defined and processes referred to are recalled. The two different aspects of fragmentation are considered but the emphasis is also put on heavy ion induced reactions. The preliminary results of an experiment performed at GANIL to study peripheral heavy ions induced reactions at intermediate energy are presented. The results of this experiment will illustrate the characteristics of projectile fragmentation and this will also give the opportunity to study projectile fragmentation in the transition region. Then nuclear fragmentation is considered which is associated with more central collisions in the case of heavy ion induced reactions. This aspect of fragmentation is also ilustrated with two heavy ion experiments in which fragments emitted at large angle have been observed

  2. Theoretical chemistry periodicities in chemistry and biology

    CERN Document Server

    Eyring, Henry

    1978-01-01

    Theoretical Chemistry: Periodicities in Chemistry and Biology, Volume 4 covers the aspects of theoretical chemistry. The book discusses the stably rotating patterns of reaction and diffusion; the chemistry of inorganic systems exhibiting nonmonotonic behavior; and population cycles. The text also describes the mathematical modeling of excitable media in neurobiology and chemistry; oscillating enzyme reactions; and oscillatory properties and excitability of the heart cell membrane. Selected topics from the theory of physico-chemical instabilities are also encompassed. Chemists, mechanical engin

  3. Self-Attractive Hartree Decomposition: Partitioning Electron Density into Smooth Localized Fragments.

    Science.gov (United States)

    Zhu, Tianyu; de Silva, Piotr; Van Voorhis, Troy

    2018-01-09

    Chemical bonding plays a central role in the description and understanding of chemistry. Many methods have been proposed to extract information about bonding from quantum chemical calculations, the majority of them resorting to molecular orbitals as basic descriptors. Here, we present a method called self-attractive Hartree (SAH) decomposition to unravel pairs of electrons directly from the electron density, which unlike molecular orbitals is a well-defined observable that can be accessed experimentally. The key idea is to partition the density into a sum of one-electron fragments that simultaneously maximize the self-repulsion and maintain regular shapes. This leads to a set of rather unusual equations in which every electron experiences self-attractive Hartree potential in addition to an external potential common for all the electrons. The resulting symmetry breaking and localization are surprisingly consistent with chemical intuition. SAH decomposition is also shown to be effective in visualization of single/multiple bonds, lone pairs, and unusual bonds due to the smooth nature of fragment densities. Furthermore, we demonstrate that it can be used to identify specific chemical bonds in molecular complexes and provides a simple and accurate electrostatic model of hydrogen bonding.

  4. Praxeological Organization of School Knowledge: A comparison of the Clapeyron equation approach in both physics and chemistry textbooks

    Directory of Open Access Journals (Sweden)

    Danilo Claro Zanardi

    2013-12-01

    Full Text Available This paper presents an overview of the Didactic Transposition and Anthropological Theory of Didactic of Chevallard and the relationship between them in order to use them as an analysis tool to understand the appearance of content on the Clapeyron equation in both books of Physics and Chemistry. Praxeological analysis revealed a common core to these two science courses, complemented by some concepts which are contextualized to each one of them. This analysis can provide elements that guide the internal didactical transposition, helping teachers of physics and chemistry to minimize the fragmentation of this content in both science courses.

  5. Optimization of secondary side water chemistry in TQNPC

    International Nuclear Information System (INIS)

    Fang Lan

    2007-01-01

    This article briefly introduces the types of corrosion that may be happened on steam generator heat exchange tubes in Qinshan CANDU6 nuclear power station and chemical effects on corrosion. The water chemistry optimization on minimzing deposition and corrosion of steam generators are introduced. The article summarizes the experiences of plant chemistry control and morpholine operation, providing guidance for optimizing secondary side water chemistry in the future, giving reference on selection of secondary side alkali agent and setting water chemistry specifications for other nuclear power stations. (authors)

  6. Analytical Chemistry Laboratory

    Science.gov (United States)

    Anderson, Mark

    2013-01-01

    The Analytical Chemistry and Material Development Group maintains a capability in chemical analysis, materials R&D failure analysis and contamination control. The uniquely qualified staff and facility support the needs of flight projects, science instrument development and various technical tasks, as well as Cal Tech.

  7. Large scale meta-analysis of fragment-based screening campaigns: privileged fragments and complementary technologies.

    Science.gov (United States)

    Kutchukian, Peter S; Wassermann, Anne Mai; Lindvall, Mika K; Wright, S Kirk; Ottl, Johannes; Jacob, Jaison; Scheufler, Clemens; Marzinzik, Andreas; Brooijmans, Natasja; Glick, Meir

    2015-06-01

    A first step in fragment-based drug discovery (FBDD) often entails a fragment-based screen (FBS) to identify fragment "hits." However, the integration of conflicting results from orthogonal screens remains a challenge. Here we present a meta-analysis of 35 fragment-based campaigns at Novartis, which employed a generic 1400-fragment library against diverse target families using various biophysical and biochemical techniques. By statistically interrogating the multidimensional FBS data, we sought to investigate three questions: (1) What makes a fragment amenable for FBS? (2) How do hits from different fragment screening technologies and target classes compare with each other? (3) What is the best way to pair FBS assay technologies? In doing so, we identified substructures that were privileged for specific target classes, as well as fragments that were privileged for authentic activity against many targets. We also revealed some of the discrepancies between technologies. Finally, we uncovered a simple rule of thumb in screening strategy: when choosing two technologies for a campaign, pairing a biochemical and biophysical screen tends to yield the greatest coverage of authentic hits. © 2014 Society for Laboratory Automation and Screening.

  8. MOJIBAKE – The Rehearsal of Word Fragments In Verbal Recall

    Directory of Open Access Journals (Sweden)

    Dr. Christiane eLange-Küttner

    2015-04-01

    Full Text Available Theories of verbal rehearsal usually assume that whole words are being rehearsed. However, words consist of letter sequences, or syllables, or word onset-vowel-coda, amongst many other conceptualizations of word structure. A more general term is the ‘grain size’ of word units (Ziegler & Goswami, 2005. In the current study, a new method measured the quantitative percentage of correctly remembered word structure. The amount of letters in the correct letter sequence as per cent of word length was calculated, disregarding missing or added letters. A forced rehearsal was tested by repeating each memory list four times. We tested low frequency (LF English words versus geographical UK town names to control for content. We also tested unfamiliar international (INT non-words and names of international (INT European towns to control for familiarity. An immediate versus distributed repetition was tested with a between-subject design. Participants responded with word fragments in their written recall especially when they had to remember unfamiliar words. While memory of whole words was sensitive to content, presentation distribution and individual sex and language differences, recall of word fragments was not. There was no trade-off between memory of word fragments with whole word recall during the repetition, instead also word fragments significantly increased. Moreover, while whole word responses correlated with each other during repetition, and word fragment responses correlated with each other during repetition, these two types of word recall responses were not correlated with each other. Thus there may be a lower layer consisting of free, sparse word fragments and an upper layer that consists of language-specific, orthographically and semantically constrained words.

  9. Mojibake – The rehearsal of word fragments in verbal recall

    Science.gov (United States)

    Lange-Küttner, Christiane; Sykorova, Eva

    2015-01-01

    Theories of verbal rehearsal usually assume that whole words are being rehearsed. However, words consist of letter sequences, or syllables, or word onset-vowel-coda, amongst many other conceptualizations of word structure. A more general term is the ‘grain size’ of word units (Ziegler and Goswami, 2005). In the current study, a new method measured the quantitative percentage of correctly remembered word structure. The amount of letters in the correct letter sequence as per cent of word length was calculated, disregarding missing or added letters. A forced rehearsal was tested by repeating each memory list four times. We tested low frequency (LF) English words versus geographical (UK) town names to control for content. We also tested unfamiliar international (INT) non-words and names of international (INT) European towns to control for familiarity. An immediate versus distributed repetition was tested with a between-subject design. Participants responded with word fragments in their written recall especially when they had to remember unfamiliar words. While memory of whole words was sensitive to content, presentation distribution and individual sex and language differences, recall of word fragments was not. There was no trade-off between memory of word fragments with whole word recall during the repetition, instead also word fragments significantly increased. Moreover, while whole word responses correlated with each other during repetition, and word fragment responses correlated with each other during repetition, these two types of word recall responses were not correlated with each other. Thus there may be a lower layer consisting of free, sparse word fragments and an upper layer that consists of language-specific, orthographically and semantically constrained words. PMID:25941500

  10. Water chemistry - one of the key technologies for safe and reliable nuclear power plant operation

    International Nuclear Information System (INIS)

    Uchida, S.; Otoha, K.; Ishigure, K.

    2006-01-01

    Full text: Full text: Water chemistry control is one of the key technologies to establish safe and reliable operation of nuclear power plants. Continuous and collaborative efforts of plant manufacturers and plant operator utilities have been focused on optimal water chemistry control, for which, a trio of requirements for water chemistry, a) better reliability of reactor structures and fuels, b) lower occupational exposure, and c) fewer radwaste sources, should be simultaneously satisfied. The research committee related to water chemistry of the Atomic Energy Society of Japan has played important roles to enhance improvement in water chemistry control, to share knowledge and experience with water chemistry among plant operators and manufacturers, to establish common technological bases for plant water chemistry and then to transfer them to the next generation related to water chemistry. Furthermore, the committee has tried to contribute to arranging R and D proposals for further improvement in water chemistry control through road map planning

  11. Assessment of EPRI water chemistry guidelines for new nuclear power plants

    International Nuclear Information System (INIS)

    Reid Richard; Kim Karen; McCree, Anisa; Eaker, Richard; Sawochka, Steve; Giannelli, Joe

    2012-09-01

    Water chemistry control technologies for nuclear power plants have been significantly enhanced over the past few decades to improve material and equipment reliability and fuel performance, and to minimize radionuclide production and transport. Chemistry Guidelines have been developed by the Electric Power Research Institute (EPRI) for currently operating plants and have been intermittently revised over the past twenty-five years for the protection of systems and components and for radiation management. As new plants are being designed for improved safety and increased power production, it is important to ensure that the designs consider implementation of state-of-the-art, industry developed water chemistry controls. In parallel, the industry will need to consider and update water chemistry guidelines as well as plant startup and operational strategies based on the advanced plant designs. EPRI has performed assessments of water chemistry control guidance or assumptions provided in design and licensing documents for several advanced plant designs. These designs include: Westinghouse AP1000 Pressurized Water Reactor AREVA US-EPR Pressurized Water Reactor Mitsubishi Nuclear Energy Systems/Mitsubishi Heavy Industries Advanced Pressurized Water Reactor Korea Hydro and Nuclear Power APR1400 Pressurized Water Reactor Toshiba Advanced Boiling Water Reactor (ABWR) General Electric-Hitachi Economic Simplified Boiling Water Reactor (ESBWR) The intent of these assessments was to identify key design differences in each of the new plant designs relative to the current operating fleet and to identify differences in water chemistry specifications or design assumptions provided in design and licensing documents for the plants in comparison to current EPRI Water Chemistry Guidelines. This paper provides a summary of the key results of these assessments. The fundamental design and operation of the advanced plants is similar to the currently operating fleet. As such, the new plants are

  12. Fragment-based drug design.

    Science.gov (United States)

    Feyfant, Eric; Cross, Jason B; Paris, Kevin; Tsao, Désirée H H

    2011-01-01

    Fragment-based drug design (FBDD), which is comprised of both fragment screening and the use of fragment hits to design leads, began more than 15 years ago and has been steadily gaining in popularity and utility. Its origin lies on the fact that the coverage of chemical space and the binding efficiency of hits are directly related to the size of the compounds screened. Nevertheless, FBDD still faces challenges, among them developing fragment screening libraries that ensure optimal coverage of chemical space, physical properties and chemical tractability. Fragment screening also requires sensitive assays, often biophysical in nature, to detect weak binders. In this chapter we will introduce the technologies used to address these challenges and outline the experimental advantages that make FBDD one of the most popular new hit-to-lead process.

  13. Cycloadditions in modern polymer chemistry.

    Science.gov (United States)

    Delaittre, Guillaume; Guimard, Nathalie K; Barner-Kowollik, Christopher

    2015-05-19

    , beyond the popular maleimide/furan couple, we present chemistries based on more reactive species, such as cyclopentadienyl or thiocarbonylthio moieties, particularly stressing the reversibility of these systems. In these two greater families, as well as in the last section on [2+2] cycloadditions, we highlight phototriggered chemistries as a powerful tool for spatially and temporally controlled materials synthesis. Clearly, cycloaddition chemistry already has and will continue to transform the field of polymer chemistry in the years to come. Applying this chemistry enables better control over polymer composition, the development of more complicated polymer architectures, the simplification of polymer library production, and the discovery of novel applications for all of these new polymers.

  14. Is Trauma Memory Special? Trauma Narrative Fragmentation in PTSD: Effects of Treatment and Response.

    Science.gov (United States)

    Bedard-Gilligan, Michele; Zoellner, Lori A; Feeny, Norah C

    2017-03-01

    Seminal theories posit that fragmented trauma memories are critical to posttraumatic stress disorder (PTSD; van der Kolk & Fisler, 1995; Brewin, 2014) and that elaboration of the trauma narrative is necessary for recovery (e.g., Foa, Huppert, & Cahill, 2006). According to fragmentation theories, trauma narrative changes, particularly for those receiving trauma-focused treatment, should accompany symptom reduction. Trauma and control narratives in 77 men and women with chronic PTSD were examined pre- and post-treatment, comparing prolonged exposure (PE) and sertraline. Utilizing self-report, rater coding, and objective coding of narrative content, fragmentation was compared across narrative types (trauma, negative, positive) by treatment modality and response, controlling for potential confounds. Although sensory components increased with PE ( d = 0.23 - 0.44), there were no consistent differences in fragmentation from pre- to post-treatment between PE and sertraline or treatment responders and non-responders. Contrary to theories, changes in fragmentation may not be a crucial mechanism underlying PTSD therapeutic recovery.

  15. Nuclear chemistry progress report

    International Nuclear Information System (INIS)

    1984-09-01

    The activities of the nuclear chemistry group at Indiana University during the period September 1, 1983 to August 31, 1984, are summarized. The primary thrust of our research program has continued to be the investigation of damped collision mechanisms at near-barrier energies and of linear momentum and energy transfer in the low-to-intermediate energy regime. In addition, during the past year we have initiated studies of complex fragment emission from highly excited nuclei and have also completed measurements relevant to understanding the origin and propagation of galactic cosmic rays. Equipment development efforts have resulted in significantly improving the resolution and solid-angle acceptance of our detector systems. The experimental program has been carried out at several accelerators including the Indiana University Cyclotron Facility, the Lawrence Berkeley Laboratory SuperHILAC, the Holifield Heavy-Ion Research Facility and the National Superconducting Cyclotron Laboratory at Michigan State University. Publications and activities are listed

  16. Complex chemistry

    International Nuclear Information System (INIS)

    Kim, Bong Gon; Kim, Jae Sang; Kim, Jin Eun; Lee, Boo Yeon

    2006-06-01

    This book introduces complex chemistry with ten chapters, which include development of complex chemistry on history coordination theory and Warner's coordination theory and new development of complex chemistry, nomenclature on complex with conception and define, chemical formula on coordination compound, symbol of stereochemistry, stereo structure and isomerism, electron structure and bond theory on complex, structure of complex like NMR and XAFS, balance and reaction on solution, an organo-metallic chemistry, biology inorganic chemistry, material chemistry of complex, design of complex and calculation chemistry.

  17. Quantum Chemistry, and Eclectic Mix: From Silicon Carbide to Size Consistency

    Energy Technology Data Exchange (ETDEWEB)

    Rintelman, Jamie Marie [Iowa State Univ., Ames, IA (United States)

    2004-12-19

    Chemistry is a field of great breadth and variety. It is this diversity that makes for both an interesting and challenging field. My interests have spanned three major areas of theoretical chemistry: applications, method development, and method evaluation. The topics presented in this thesis are as follows: (1) a multi-reference study of the geometries and relative energies of four atom silicon carbide clusters in the gas phase; (2) the reaction of acetylene on the Si(100)-(2x1) surface; (3) an improvement to the Effective Fragment Potential (EFP) solvent model to enable the study of reactions in both aqueous and nonaqueous solution; and (4) an evaluation of the size consistency of Multireference Perturbation Theory (MRPT). In the following section, the author briefly discusses two topics central to, and present throughout, this thesis: Multi-reference methods and Quantum Mechanics/Molecular Mechanics (QM/MM) methods.

  18. Fuel Chemistry Division: progress report for 1987

    International Nuclear Information System (INIS)

    1990-01-01

    The progress of research and development activities of the Fuel Chemistry Division of the Bhabha Atomic Research Centre, Bombay, during 1987 is reported in the form of summaries which are arranged under the headings: Fuel Development Chemistry, Chemistry of Actinides, Chemical Quality Control of Fuel, and Studies related to Nuclear Material Accounting. A list of publications by the members of the Division during the report period is given at the end of the report. (M.G.B.). refs., 15 figs., 85 tabs

  19. Water chemistry and behavior of materials in PWRs and BWRs

    Energy Technology Data Exchange (ETDEWEB)

    Aaltonen, P; Hanninen, H [VTT Manufacturing Technology, Espoo (Finland)

    1997-09-01

    Water chemistry plays a major role in corrosion and in activity transport in NPP`s. Although a full understanding of all mechanisms involved in corrosion does not exist, controlling of the water chemistry has achieved good results in recent years. Water chemistry impacts upon the operational safety of LWR`s in two main ways: integrity of pressure boundary materials and, activity transport and out-of-core radiation fields. This paper will describe application of water chemistry control in operating reactors to prevent corrosion. Some problems experienced in LWR`s will be reviewed for the design of the nuclear heating reactors (NHR). (author). 18 refs, 10 figs, 5 tabs.

  20. Water chemistry and behavior of materials in PWRs and BWRs

    International Nuclear Information System (INIS)

    Aaltonen, P.; Hanninen, H.

    1997-01-01

    Water chemistry plays a major role in corrosion and in activity transport in NPP's. Although a full understanding of all mechanisms involved in corrosion does not exist, controlling of the water chemistry has achieved good results in recent years. Water chemistry impacts upon the operational safety of LWR's in two main ways: integrity of pressure boundary materials and, activity transport and out-of-core radiation fields. This paper will describe application of water chemistry control in operating reactors to prevent corrosion. Some problems experienced in LWR's will be reviewed for the design of the nuclear heating reactors (NHR). (author). 18 refs, 10 figs, 5 tabs

  1. Study of the fragmentation of astrophysical interest molecules (CnHm) induced by high velocity collision

    International Nuclear Information System (INIS)

    Tuna, Th.

    2008-07-01

    This work shows the study of atom-molecule collision processes in the high velocity domain (v=4,5 a.u). The molecules concerned by this work are small unsaturated hydrocarbons C 1-4 H and C 3 H 2 . Molecules are accelerated with the Tandem accelerator in Orsay and their fragmentation is analyzed by the 4π, 100% efficient detector, AGAT. Thanks to a shape analysis of the current signal from the silicon detectors in association with the well known grid method, we are able to measure all the fragmentation channels of the incident molecule. These dissociation measurements have been introduced in the modelization of two objects of the interstellar medium in which a lot of hydrocarbon molecules have been observed (TMC1, horse-head nebula). We have extended our branching ratios obtained by high velocity collision to other electronic processes included in the chemical database like photodissociation and dissociative recombination. This procedure is feasible under an assumption of the statistical point of view of the molecular fragmentation. The deviations following our modification are very small in the modelization of TMC1 but significant in the photodissociation region. The first part is dedicated to the description of the experimental setting that has enabled us to study the fragmentation of C n H m molecules: the Orsay's Tandem accelerator and the Agat detector. The second part deals with negative ion sources and particularly with the Sahat source that is based on electronic impact and has shown good features for the production of anions and correct stability for its use with accelerators. The third part is dedicated to the experimental results in terms of cross-sections, number of fragments and branching ratios, associated to the various collisional processes. The last part presents an application of our measurement of fragmentation data to astro-chemistry. In this field, the simulation codes of the inter-stellar medium require databases of chemical reactions that

  2. Assessment of fragment projection hazard: probability distributions for the initial direction of fragments.

    Science.gov (United States)

    Tugnoli, Alessandro; Gubinelli, Gianfilippo; Landucci, Gabriele; Cozzani, Valerio

    2014-08-30

    The evaluation of the initial direction and velocity of the fragments generated in the fragmentation of a vessel due to internal pressure is an important information in the assessment of damage caused by fragments, in particular within the quantitative risk assessment (QRA) of chemical and process plants. In the present study an approach is proposed to the identification and validation of probability density functions (pdfs) for the initial direction of the fragments. A detailed review of a large number of past accidents provided the background information for the validation procedure. A specific method was developed for the validation of the proposed pdfs. Validated pdfs were obtained for both the vertical and horizontal angles of projection and for the initial velocity of the fragments. Copyright © 2014 Elsevier B.V. All rights reserved.

  3. Novel Anti-Biofouling Soft Contact Lens: l-Cysteine Conjugated Amphiphilic Conetworks via RAFT and Thiol-Ene Click Chemistry.

    Science.gov (United States)

    Zhang, Chengfeng; Liu, Ziyuan; Wang, Haiye; Feng, Xiaofeng; He, Chunju

    2017-07-01

    A unique l-cysteine conjugated antifouling amphiphilic conetwork (APCN) is synthesized through end-crosslinking of well-defined triblock copolymers poly(allyl methacrylate)-b-poly(ethylene glycol)-b-poly(allyl methacrylate) via a combination of reversible addition-fragmentation chain transfer (RAFT) polymerization and thiol-ene "click" chemistry. The synthesized poly(ethylene glycol) macro-RAFT agent initiates the polymerization of allyl methacrylate in a controlled manner. The vinyl pendant groups of the precursor partially conjugate with l-cysteine and the rest fully crosslink with mercaptopropyl-containing siloxane via thiol-ene click chemistry under UV irradiation into APCNs, which show distinguished properties, that is, excellent biocompatibility, more than 39.6% water content, 101 barrers oxygen permeability, optimized mechanical properties, and more than 93% visible light transmittance. What's more, the resultant APCNs exhibit eminent resistance to protein adsorption, where the bovine serum albumin and lysozyme adsorption are decreased to 12 and 21 µg cm -2 , respectively. The outstanding properties of APCNs depend on the RAFT controlled method, which precisely designs the hydrophilic/hydrophobic segments and eventually greatly improves the crosslinking efficiency and homogeneity. Meantime, the l-cysteine monolayer can effectively reduce the surface hydrophobicity and prevent protein adsorption, which exhibits the viability for antifouling surface over and under ophthalmic devices, suggesting a promising soft contact lens. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Knowledge-based Fragment Binding Prediction

    Science.gov (United States)

    Tang, Grace W.; Altman, Russ B.

    2014-01-01

    Target-based drug discovery must assess many drug-like compounds for potential activity. Focusing on low-molecular-weight compounds (fragments) can dramatically reduce the chemical search space. However, approaches for determining protein-fragment interactions have limitations. Experimental assays are time-consuming, expensive, and not always applicable. At the same time, computational approaches using physics-based methods have limited accuracy. With increasing high-resolution structural data for protein-ligand complexes, there is now an opportunity for data-driven approaches to fragment binding prediction. We present FragFEATURE, a machine learning approach to predict small molecule fragments preferred by a target protein structure. We first create a knowledge base of protein structural environments annotated with the small molecule substructures they bind. These substructures have low-molecular weight and serve as a proxy for fragments. FragFEATURE then compares the structural environments within a target protein to those in the knowledge base to retrieve statistically preferred fragments. It merges information across diverse ligands with shared substructures to generate predictions. Our results demonstrate FragFEATURE's ability to rediscover fragments corresponding to the ligand bound with 74% precision and 82% recall on average. For many protein targets, it identifies high scoring fragments that are substructures of known inhibitors. FragFEATURE thus predicts fragments that can serve as inputs to fragment-based drug design or serve as refinement criteria for creating target-specific compound libraries for experimental or computational screening. PMID:24762971

  5. A behaviorally-explicit approach for delivering vaccine baits to mesopredators to control epizootics in fragmented landscapes.

    Directory of Open Access Journals (Sweden)

    James C Beasley

    Full Text Available Despite the widespread use of aerial baiting to manage epizootics among free-ranging populations, particularly in rabies management, bait acceptance and seroconversion rates often are lower than required to eliminate spread of disease. Our objectives in this study, therefore, were to evaluate the performance of stratified bait distribution models derived from resource selection functions (RSF on uptake of placebo rabies baits by raccoons (Procyon lotor and Virginia opossums (Didelphis virginiana, as well as the probability of bait uptake as a function of proximity to bait distribution areas in fragmented agricultural ecosystems. Among 478 raccoons and 108 opossums evaluated for presence of Rhodamine B (RB across 8 sites, only 26% of raccoons and 20% of opossums exhibited marking consistent with bait consumption 14-24 days post-baiting. The effective area treated, based on 90% kernel density estimators of marked individuals, ranged from 99-240 ha larger than bait distribution zones, with RB marked individuals captured up to 753 m beyond the bait zone. Despite incorporation of RSF data into bait distribution models, no differences in uptake rates were observed between treatment and control sites. These data likely reflect the underlying constraints imposed by the loss and fragmentation of habitat on animal movement in heterogeneous landscapes, forcing individuals to optimize movements at coarse (i.e., patch-level rather than fine spatial scales in highly fragmented environments. Our data also confirm that the probability of bait acceptance decreases with increasing distance from bait zone interiors, even within the zone itself. Thus, although bait acceptance was confirmed beyond bait zone boundaries, the proportion of vaccinated individuals may comprise a small minority of the population at increasing distances from baiting interiors. These data suggest focal baiting creates a buffered area of treated individuals around bait zones or bait stations

  6. Fragmentation in the branching coral Acropora palmata (Lamarck): growth, survivorship, and reproduction of colonies and fragments.

    Science.gov (United States)

    Lirman

    2000-08-23

    Acropora palmata, a branching coral abundant on shallow reef environments throughout the Caribbean, is susceptible to physical disturbance caused by storms. Accordingly, the survivorship and propagation of this species are tied to its capability to recover after fragmentation. Fragments of A. palmata comprised 40% of ramets within populations that had experienced recent storms. While the survivorship of A. palmata fragments was not directly related to the size of fragments, removal of fragments from areas where they settled was influenced by size. Survivorship of fragments was also affected by type of substratum; the greatest mortality (58% loss within the first month) was observed on sand, whereas fragments placed on top of live colonies of A. palmata fused to the underlying tissue and did not experience any losses. Fragments created by Hurricane Andrew on a Florida reef in August 1992 began developing new growth (proto-branches) 7 months after the storm. The number of proto-branches on fragments was dependent on size, but growth was not affected by the size of fragments. Growth-rates of proto-branches increased exponentially with time (1.7 cm year(-1) for 1993-1994, 2.7 cm year(-1) for 1994-1995, 4.2 cm year(-1) for 1995-1996, and 6.5 cm year(-1) for 1996-1997), taking over 4 years for proto-branches to achieve rates comparable to those of adult colonies on the same reef (6.9 cm year(-1)). In addition to the initial mortality and reduced growth-rates, fragmentation resulted in a loss of reproductive potential. Neither colonies that experienced severe fragmentation nor fragments contained gametes until 4 years after the initial damage. Although A. palmata may survive periodic fragmentation, the long-term effects of this process will depend ultimately on the balance between the benefits and costs of this process.

  7. Plasminogen fragments K 1-3 and K 5 bind to different sites in fibrin fragment DD.

    Science.gov (United States)

    Grinenko, T V; Kapustianenko, L G; Yatsenko, T A; Yusova, O I; Rybachuk, V N

    2016-01-01

    Specific plasminogen-binding sites of fibrin molecule are located in Аα148-160 regions of C-terminal domains. Plasminogen interaction with these sites initiates the activation process of proenzyme and subsequent fibrin lysis. In this study we investigated the binding of plasminogen fragments K 1-3 and K 5 with fibrin fragment DD and their effect on Glu-plasminogen interaction with DD. It was shown that the level of Glu-plasminogen binding to fibrin fragment DD is decreased by 50-60% in the presence of K 1-3 and K 5. Fragments K 1-3 and K 5 have high affinity to fibrin fragment DD (Kd is 0.02 for K 1-3 and 0.054 μМ for K 5). K 5 interaction is independent and K 1-3 is partly dependent on C-terminal lysine residues. K 1-3 interacts with complex of fragment DD-immobilized K 5 as well as K 5 with complex of fragment DD-immobilized K 1-3. The plasminogen fragments do not displace each other from binding sites located in fibrin fragment DD, but can compete for the interaction. The results indicate that fibrin fragment DD contains different binding sites for plasminogen kringle fragments K 1-3 and K 5, which can be located close to each other. The role of amino acid residues of fibrin molecule Аα148-160 region in interaction with fragments K 1-3 and K 5 is discussed.

  8. Fractal statistics of brittle fragmentation

    Directory of Open Access Journals (Sweden)

    M. Davydova

    2013-04-01

    Full Text Available The study of fragmentation statistics of brittle materials that includes four types of experiments is presented. Data processing of the fragmentation of glass plates under quasi-static loading and the fragmentation of quartz cylindrical rods under dynamic loading shows that the size distribution of fragments (spatial quantity is fractal and can be described by a power law. The original experimental technique allows us to measure, apart from the spatial quantity, the temporal quantity - the size of time interval between the impulses of the light reflected from the newly created surfaces. The analysis of distributions of spatial (fragment size and temporal (time interval quantities provides evidence of obeying scaling laws, which suggests the possibility of self-organized criticality in fragmentation.

  9. Controlling female cancer in Argentina. Divergent initiatives and the road to fragmentation.

    Science.gov (United States)

    Eraso, Yolanda

    2014-01-01

    This article analyses the organisation of cancer control in Argentina, with a special focus on the initiatives, institutions, and models that targeted female or gynaecological cancers. It identifies and examines the main factors in the process of elaborating a national policy to control the disease drawing on a series of actors and instruments such as the state, medical professionals, institutions and services, and the use of technology (notably diagnostic tools) for the detection of the disease. It traces the developments in the organisation highlighting its transformations from a centralising to a decentralised model of service provision. Using the concept of "path-dependence" the article examines the continuities and changes observed in the organisation of female cancer critically signalling the particular time at which a path was taken where "fragmentation" became consolidated within the health system. It also argues that it was within the field of cancer diagnosis that Argentinian doctors first sought to create the foundational structures of cancer organisation. The article contends that the path-dependence analytical approach helps us acknowledge the importance of historical analysis in the identification of factors that led to the lack of service coordination, including the persistent strain between national/provincial states that hampered the development of comprehensive programmes, aspects that have continued to mark efforts in the elaboration of cancer policies to the present day.

  10. Network analysis reveals multiscale controls on streamwater chemistry

    Science.gov (United States)

    Kevin J. McGuire; Christian E. Torgersen; Gene E. Likens; Donald C. Buso; Winsor H. Lowe; Scott W. Bailey

    2014-01-01

    By coupling synoptic data from a basin-wide assessment of streamwater chemistry with network-based geostatistical analysis, we show that spatial processes differentially affect biogeochemical condition and pattern across a headwater stream network. We analyzed a high-resolution dataset consisting of 664 water samples collected every 100 m throughout 32 tributaries in...

  11. Impact of the Flipped Classroom on Student Performance and Retention: A Parallel Controlled Study in General Chemistry

    Science.gov (United States)

    Ryan, Michael D.; Reid, Scott A.

    2016-01-01

    Despite much recent interest in the flipped classroom, quantitative studies are slowly emerging, particularly in the sciences. We report a year-long parallel controlled study of the flipped classroom in a second-term general chemistry course. The flipped course was piloted in the off-semester course in Fall 2014, and the availability of the…

  12. An Overview of the EPRI PWR Primary Chemistry Program

    International Nuclear Information System (INIS)

    Perkins, David; Fruzzetti, Keith; Haas, Carey; Wells, Dan

    2012-09-01

    Primary chemistry controls continue to evolve, impacting long term equipment reliability goals, optimized core designs, and radiation dose management practices. Chemistry initiatives include increased primary system pH (T) , zinc injection, and optimization of primary system hydrogen concentration. Nevertheless, utilities are faced with ever changing challenges as fuel vendors continue to optimize core power densities coupled with longer operating cycles and material replacement efforts. These challenges must be collaboratively addressed by the plant chemists, engineers, and operators. Operational chemistry has changed dramatically over the years with increased primary pH (T) programs requiring some utilities to operate with up to 6 ppm lithium or slightly higher. Coupled with primary pH (T) program optimization, are ongoing EPRI research efforts attempting to develop an optimized hydrogen control program balancing material issues associated with primary water stress corrosion cracking (PWSCC) crack growth rate against fuel concerns associated with increased hydrogen concentrations. One of the most significant primary chemistry changes that effectively balances the demands of materials, fuels, chemistry and dose management strategies is zinc injection into the primary coolant. Since 1994 when Farley initiated zinc injection, zinc injection has been successfully injected at over 70 pressurized water reactors world-wide. Combining operational chemistry with shutdown chemistry controls provides the plant chemist with a technically based and balanced approach to fuel and material integrity as well as dose management strategies. Shutdown chemistry has continually evolved since the 1970's when the chemist was primarily concerned with fission products. Now the chemist must manage corrosion product release, and support Outage Management and Radiation Protection through the performance of a controlled shutdown. In part, this change was driven as plant materials evolved

  13. BWR normal water chemistry guidelines: 1986 revision

    International Nuclear Information System (INIS)

    1988-09-01

    Boiling water reactors (BWRs) have experienced stress corrosion cracking in the reactor cooling system piping resulting in adverse impacts on plant availability and personnel radiation exposure. The BWR Owners Group and EPRI have sponsored a major research and development program to provide remedies for this stress corrosion cracking problem. This work shows that the likelihood of cracking depends on the plant's water chemistry performance (environment) as well as on material condition and stress level. Plant experience and other research demonstrate that water quality also affects fuel performance and radiation field buildup in BWRs. This report,''BWR Normal Water Chemistry Guidelines: 1986 Revision,'' presents suggested generic water chemistry specifications, justifies the proposed water chemistry limits, suggests responses to out-of-specification water chemistry, discusses available chemical analysis methods as well as data management and surveillance schemes, and details the management philosophy required to successfully implement a water chemistry control program. An appendix contains recommendations for water quality of auxiliary systems. 73 refs., 20 figs., 9 tabs

  14. VUV photo-processing of PAH cations: quantitative study on the ionization versus fragmentation processes.

    Science.gov (United States)

    Zhen, Junfeng; Castillo, Sarah Rodriguez; Joblin, Christine; Mulas, Giacomo; Sabbah, Hassan; Giuliani, Alexandre; Nahon, Laurent; Martin, Serge; Champeaux, Jean-Philippe; Mayer, Paul M

    2016-05-10

    Interstellar polycyclic aromatic hydrocarbons (PAHs) are strongly affected by the absorption of vacuum ultraviolet (VUV) photons in the interstellar medium (ISM), yet the branching ratio between ionization and fragmentation is poorly studied. This is crucial for the stability and charge state of PAHs in the ISM in different environments, affecting in turn the chemistry, the energy balance, and the contribution of PAHs to the extinction and emission curves. We studied the interaction of PAH cations with VUV photons in the 7 - 20 eV range from the synchrotron SOLEIL beamline, DESIRS. We recorded by action spectroscopy the relative intensities of photo-fragmentation and photo-ionization for a set of eight PAH cations ranging in size from 14 to 24 carbon atoms, with different structures. At photon energies below ~13.6 eV fragmentation dominates for the smaller species, while for larger species ionization is immediately competitive after the second ionization potential (IP). At higher photon energies, all species behave similarly, the ionization yield gradually increases, leveling off between 0.8 and 0.9 at ~18 eV. Among isomers, PAH structure appears to mainly affect the fragmentation cross section, but not the ionization cross section. We also measured the second IP for all species and the third IP for two of them, all are in good agreement with theoretical ones confirming that PAH cations can be further ionized in the diffuse ISM. Determining actual PAH dication abundances in the ISM will require detailed modeling. Our measured photo-ionization yields for several PAH cations provide a necessary ingredient for such models.

  15. VUV PHOTO-PROCESSING OF PAH CATIONS: QUANTITATIVE STUDY ON THE IONIZATION VERSUS FRAGMENTATION PROCESSES

    Energy Technology Data Exchange (ETDEWEB)

    Zhen, Junfeng; Castillo, Sarah Rodriguez; Joblin, Christine; Mulas, Giacomo; Sabbah, Hassan [Université de Toulouse, UPS-OMP, Institut de Recherche en Astrophysique et Planétologie, Toulouse (France); Giuliani, Alexandre; Nahon, Laurent [Synchrotron SOLEIL, LOrme des Merisiers, F-91192 Gif sur Yvette Cedex (France); Martin, Serge [Institut Lumière Matière, Université Lyon 1-CNRS, Université de Lyon, F-69622 Villeurbanne cedex (France); Champeaux, Jean-Philippe [Laboratoire Collisions Agrégats Réactivité, Université de Toulouse, UPS-IRSAMC, CNRS, 118 Route de Narbonne, Bat 3R1B4, F-31062 Toulouse Cedex 9 (France); Mayer, Paul M., E-mail: christine.joblin@irap.omp.eu [Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa K1N 6N5 (Canada)

    2016-05-10

    Interstellar polycyclic aromatic hydrocarbons (PAHs) are strongly affected by the absorption of vacuum ultraviolet (VUV) photons in the interstellar medium (ISM), yet the branching ratio between ionization and fragmentation is poorly studied. This is crucial for the stability and charge state of PAHs in the ISM in different environments, affecting in turn the chemistry, the energy balance, and the contribution of PAHs to the extinction and emission curves. We studied the interaction of PAH cations with VUV photons in the 7–20 eV range from the synchrotron SOLEIL beamline, DESIRS. We recorded by action spectroscopy the relative intensities of photo-fragmentation and photo-ionization for a set of eight PAH cations ranging in size from 14 to 24 carbon atoms, with different structures. At photon energies below ∼13.6 eV fragmentation dominates for the smaller species, while for larger species ionization is immediately competitive after the second ionization potential (IP). At higher photon energies all species behave similarly; the ionization yield gradually increases, leveling off between 0.8 and 0.9 at ∼18 eV. Among isomers, PAH structure appears to mainly affect the fragmentation cross section but not the ionization cross section. We also measured the second IP for all species and the third IP for two of them; all are in good agreement with theoretical ones, confirming that PAH cations can be further ionized in the diffuse ISM. Determining actual PAH dication abundances in the ISM will require detailed modeling. Our measured photo-ionization yields for several PAH cations provide a necessary ingredient for such models.

  16. VUV PHOTO-PROCESSING OF PAH CATIONS: QUANTITATIVE STUDY ON THE IONIZATION VERSUS FRAGMENTATION PROCESSES

    International Nuclear Information System (INIS)

    Zhen, Junfeng; Castillo, Sarah Rodriguez; Joblin, Christine; Mulas, Giacomo; Sabbah, Hassan; Giuliani, Alexandre; Nahon, Laurent; Martin, Serge; Champeaux, Jean-Philippe; Mayer, Paul M.

    2016-01-01

    Interstellar polycyclic aromatic hydrocarbons (PAHs) are strongly affected by the absorption of vacuum ultraviolet (VUV) photons in the interstellar medium (ISM), yet the branching ratio between ionization and fragmentation is poorly studied. This is crucial for the stability and charge state of PAHs in the ISM in different environments, affecting in turn the chemistry, the energy balance, and the contribution of PAHs to the extinction and emission curves. We studied the interaction of PAH cations with VUV photons in the 7–20 eV range from the synchrotron SOLEIL beamline, DESIRS. We recorded by action spectroscopy the relative intensities of photo-fragmentation and photo-ionization for a set of eight PAH cations ranging in size from 14 to 24 carbon atoms, with different structures. At photon energies below ∼13.6 eV fragmentation dominates for the smaller species, while for larger species ionization is immediately competitive after the second ionization potential (IP). At higher photon energies all species behave similarly; the ionization yield gradually increases, leveling off between 0.8 and 0.9 at ∼18 eV. Among isomers, PAH structure appears to mainly affect the fragmentation cross section but not the ionization cross section. We also measured the second IP for all species and the third IP for two of them; all are in good agreement with theoretical ones, confirming that PAH cations can be further ionized in the diffuse ISM. Determining actual PAH dication abundances in the ISM will require detailed modeling. Our measured photo-ionization yields for several PAH cations provide a necessary ingredient for such models.

  17. VUV photo-processing of PAH cations: quantitative study on the ionization versus fragmentation processes

    Science.gov (United States)

    Zhen, Junfeng; Castillo, Sarah Rodriguez; Joblin, Christine; Mulas, Giacomo; Sabbah, Hassan; Giuliani, Alexandre; Nahon, Laurent; Martin, Serge; Champeaux, Jean-Philippe; Mayer, Paul M.

    2016-01-01

    Interstellar polycyclic aromatic hydrocarbons (PAHs) are strongly affected by the absorption of vacuum ultraviolet (VUV) photons in the interstellar medium (ISM), yet the branching ratio between ionization and fragmentation is poorly studied. This is crucial for the stability and charge state of PAHs in the ISM in different environments, affecting in turn the chemistry, the energy balance, and the contribution of PAHs to the extinction and emission curves. We studied the interaction of PAH cations with VUV photons in the 7 – 20 eV range from the synchrotron SOLEIL beamline, DESIRS. We recorded by action spectroscopy the relative intensities of photo-fragmentation and photo-ionization for a set of eight PAH cations ranging in size from 14 to 24 carbon atoms, with different structures. At photon energies below ~13.6 eV fragmentation dominates for the smaller species, while for larger species ionization is immediately competitive after the second ionization potential (IP). At higher photon energies, all species behave similarly, the ionization yield gradually increases, leveling off between 0.8 and 0.9 at ~18 eV. Among isomers, PAH structure appears to mainly affect the fragmentation cross section, but not the ionization cross section. We also measured the second IP for all species and the third IP for two of them, all are in good agreement with theoretical ones confirming that PAH cations can be further ionized in the diffuse ISM. Determining actual PAH dication abundances in the ISM will require detailed modeling. Our measured photo-ionization yields for several PAH cations provide a necessary ingredient for such models. PMID:27212712

  18. Fragmentation of Protein Kinase N (PKN) in the Hydrocephalic Rat Brain

    International Nuclear Information System (INIS)

    Okii, Norifumi; Amano, Taku; Seki, Takahiro; Matsubayashi, Hiroaki; Mukai, Hideyuki; Ono, Yoshitaka; Kurisu, Kaoru; Sakai, Norio

    2007-01-01

    PKN (protein kinase N; also called protein kinase C-related kinase (PRK-1)), is a serine/threonine protein kinase that is ubiquitously expressed in several organs, including the brain. PKN has a molecular mass of 120 kDa and has two domains, a regulatory and a catalytic domain, in its amino-terminals and carboxyl-terminus, respectively. Although the role of PKN has not been fully elucidated, previous studies have revealed that PKN is cleaved to a constitutively active catalytic fragment of 55 kDa in response to apoptotic signals. Hydrocephalus is a pathological condition caused by insufficient cerebrospinal fluid (CSF) circulation and subsequent excess of CSF in the brain. In this study, in order to elucidate the role of PKN in the pathophysiology of hydrocephalus, we examined PKN fragmentation in hydrocephalic model rats. Hydrocephalus was induced in rats by injecting kaolin into the cisterna magna. Kaolin-induced rats (n=60) were divided into three groups according to the observation period after treatment (group 1: 3–6 weeks, group 2: 7–12 weeks, and group 3: 13–18 weeks). Sham-treated control rats, injected with sterile saline (n=20), were similarly divided into three groups. Spatial learning ability was estimated by a modified water maze test. Thereafter, brains were cut into slices and ventricular dilatation was estimated. Fragmentation of PKN was observed by Western blotting in samples collected from the parietal cortex, striatum, septal nucleus, hippocampus, and periaqueductal gray matter. All kaolin-induced rats showed ventricular dilatation. Most of them showed less spatial learning ability than those of sham-treated controls. In most regions, fragmentation of PKN had occurred in a biphasic manner more frequently than that in controls. The appearance of PKN fragmentation in periaqueductal gray matter was correlated with the extent of ventricular dilation and spatial learning disability. These results revealed that PKN fragmentation was observed in

  19. Chameleon fragmentation

    Energy Technology Data Exchange (ETDEWEB)

    Brax, Philippe [Institut de Physique Théorique, CEA, IPhT, CNRS, URA 2306, F-91191Gif/Yvette Cedex (France); Upadhye, Amol, E-mail: philippe.brax@cea.fr, E-mail: aupadhye@anl.gov [Institute for the Early Universe, Ewha University, International Education, Building #601, 11-1, Daehyun-Dong Seodaemun-Gu, Seoul 120-750 (Korea, Republic of)

    2014-02-01

    A scalar field dark energy candidate could couple to ordinary matter and photons, enabling its detection in laboratory experiments. Here we study the quantum properties of the chameleon field, one such dark energy candidate, in an ''afterglow'' experiment designed to produce, trap, and detect chameleon particles. In particular, we investigate the possible fragmentation of a beam of chameleon particles into multiple particle states due to the highly non-linear interaction terms in the chameleon Lagrangian. Fragmentation could weaken the constraints of an afterglow experiment by reducing the energy of the regenerated photons, but this energy reduction also provides a unique signature which could be detected by a properly-designed experiment. We show that constraints from the CHASE experiment are essentially unaffected by fragmentation for φ{sup 4} and 1/φ potentials, but are weakened for steeper potentials, and we discuss possible future afterglow experiments.

  20. Chameleon fragmentation

    International Nuclear Information System (INIS)

    Brax, Philippe; Upadhye, Amol

    2014-01-01

    A scalar field dark energy candidate could couple to ordinary matter and photons, enabling its detection in laboratory experiments. Here we study the quantum properties of the chameleon field, one such dark energy candidate, in an ''afterglow'' experiment designed to produce, trap, and detect chameleon particles. In particular, we investigate the possible fragmentation of a beam of chameleon particles into multiple particle states due to the highly non-linear interaction terms in the chameleon Lagrangian. Fragmentation could weaken the constraints of an afterglow experiment by reducing the energy of the regenerated photons, but this energy reduction also provides a unique signature which could be detected by a properly-designed experiment. We show that constraints from the CHASE experiment are essentially unaffected by fragmentation for φ 4 and 1/φ potentials, but are weakened for steeper potentials, and we discuss possible future afterglow experiments

  1. Radioanalytical Chemistry for Automated Nuclear Waste Process Monitoring

    International Nuclear Information System (INIS)

    Egorov, Oleg B.; Grate, Jay W.; DeVol, Timothy A.

    2004-01-01

    This research program is directed toward rapid, sensitive, and selective determination of beta and alpha-emitting radionuclides such as 99Tc, 90Sr, and trans-uranium (TRU) elements in low activity waste (LAW) processing streams. The overall technical approach is based on automated radiochemical measurement principles, which entails integration of sample treatment and separation chemistries and radiometric detection within a single functional analytical instrument. Nuclear waste process streams are particularly challenging for rapid analytical methods due to the complex, high-ionic-strength, caustic brine sample matrix, the presence of interfering radionuclides, and the variable and uncertain speciation of the radionuclides of interest. As a result, matrix modification, speciation control, and separation chemistries are required for use in automated process analyzers. Significant knowledge gaps exist relative to the design of chemistries for such analyzers so that radionuclides can be quantitatively and rapidly separated and analyzed in solutions derived from low-activity waste processing operations. This research is addressing these knowledge gaps in the area of separation science, nuclear detection, and analytical chemistry and instrumentation. The outcome of these investigations will be the knowledge necessary to choose appropriate chemistries for sample matrix modification and analyte speciation control and chemistries for rapid and selective separation and preconcentration of target radionuclides from complex sample matrices. In addition, new approaches for quantification of alpha emitters in solution using solid-state diode detectors, as well as improved instrumentation and signal processing techniques for use with solid-state and scintillation detectors, will be developed. New knowledge of the performance of separation materials, matrix modification and speciation control chemistries, instrument configurations, and quantitative analytical approaches will

  2. Generalized fragment picking in Rosetta: design, protocols and applications.

    Directory of Open Access Journals (Sweden)

    Dominik Gront

    Full Text Available The Rosetta de novo structure prediction and loop modeling protocols begin with coarse grained Monte Carlo searches in which the moves are based on short fragments extracted from a database of known structures. Here we describe a new object oriented program for picking fragments that greatly extends the functionality of the previous program (nnmake and opens the door for new approaches to structure modeling. We provide a detailed description of the code design and architecture, highlighting its modularity, and new features such as extensibility, total control over the fragment picking workflow and scoring system customization. We demonstrate that the program provides at least as good building blocks for ab-initio structure prediction as the previous program, and provide examples of the wide range of applications that are now accessible.

  3. Measurement and control of in-plane surface chemistry during the oxidation of H-terminated (111) Si

    Science.gov (United States)

    Gokce, Bilal; Adles, Eric J.; Aspnes, David E.; Gundogdu, Kenan

    2010-01-01

    In-plane directional control of surface chemistry during interface formation can lead to new opportunities regarding device structures and applications. Control of this type requires techniques that can probe and hence provide feedback on the chemical reactivity of bonds not only in specific directions but also in real time. Here, we demonstrate both control and measurement of the oxidation of H-terminated (111) Si. Control is achieved by externally applying uniaxial strain, and measurement by second-harmonic generation (SHG) together with the anisotropic-bond model of nonlinear optics. In this system anisotropy results because bonds in the strain direction oxidize faster than those perpendicular to it, leading in addition to transient structural changes that can also be detected at the bond level by SHG. PMID:20876145

  4. Sperm DNA fragmentation, recurrent implantation failure and recurrent miscarriage

    Directory of Open Access Journals (Sweden)

    Carol Coughlan

    2015-01-01

    Full Text Available Evidence is increasing that the integrity of sperm DNA may also be related to implantation failure and recurrent miscarriage (RM. To investigate this, the sperm DNA fragmentation in partners of 35 women with recurrent implantation failure (RIF following in vitro fertilization, 16 women diagnosed with RM and seven recent fathers (control were examined. Sperm were examined pre- and post-density centrifugation by the sperm chromatin dispersion (SCD test and the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL assay. There were no significant differences in the age of either partner or sperm concentration, motility or morphology between three groups. Moreover, there were no obvious differences in sperm DNA fragmentation measured by either test. However, whilst on average sperm DNA fragmentation in all groups was statistically lower in prepared sperm when measured by the SCD test, this was not seen with the results from the TUNEL assay. These results do not support the hypothesis that sperm DNA fragmentation is an important cause of RIF or RM, or that sperm DNA integrity testing has value in such patients. It also highlights significant differences between test methodologies and sperm preparation methods in interpreting the data from sperm DNA fragmentation tests.

  5. Closed cooling water chemistry guidelines revision

    International Nuclear Information System (INIS)

    McElrath, Joel; Breckenridge, Richard

    2014-01-01

    This second revision of the Closed Cooling Water Chemistry Guideline addresses the use of chemicals and monitoring methods to mitigate corrosion, fouling, and microbiological growth in the closed cooling-water (CCW) systems of nuclear and fossil-fueled power plants. This revision has been endorsed by the utility chemistry community and represents another step in developing a more proactive chemistry program to limit or control closed cooling system degradation with increased consideration of corporate resources and plant-specific design and operating concerns. These guidelines were developed using laboratory data, operating experience, and input from organizations and utilities within and outside of the United States of America. It is the intent of the Revision Committee that these guidelines are applicable to all nuclear and fossil-fueled generating stations around the world. A committee of industry experts—including utility specialists, Institute of Nuclear Power Operations representatives, water-treatment service-company representatives, consultants, a primary contractor, and EPRI staff—collaborated in reviewing available data on closed cooling-water system corrosion and microbiological issues. Recognizing that each plant owner has a unique set of design, operating, and corporate concerns, the Guidelines Committee developed a methodology for plant-specific optimization. The guideline provides the technical basis for a reasonable but conservative set of chemical treatment and monitoring programs. The use of operating ranges for the various treatment chemicals discussed in this guideline will allow a power plant to limit corrosion, fouling, and microbiological growth in CCW systems to acceptable levels. The guideline now includes closed cooling chemistry regimes proven successful in use in the international community. The guideline provides chemistry constraints for the use of phosphates control, as well as pure water with pH control. (author)

  6. Universality of projectile fragmentation model

    International Nuclear Information System (INIS)

    Chaudhuri, G.; Mallik, S.; Das Gupta, S.

    2012-01-01

    Presently projectile fragmentation reaction is an important area of research as it is used for the production of radioactive ion beams. In this work, the recently developed projectile fragmentation model with an universal temperature profile is used for studying the charge distributions of different projectile fragmentation reactions with different projectile target combinations at different incident energies. The model for projectile fragmentation consists of three stages: (i) abrasion, (ii) multifragmentation and (iii) evaporation

  7. Development of a diagnostic expert system for secondary water chemistry

    International Nuclear Information System (INIS)

    Suganuma, S.; Ishikawa, S.; Kato, A.; Yamauchi, S.; Hattori, T.; Yoshikawa, T.; Miyamoto, S.

    1990-01-01

    Water chemistry control for the secondary side of the PWR plants is one of the most important tasks for maintaining the reliability of plant equipment and for extending the operating life of the plant. Water chemistry control should be maintained according to the plant chemist' considered judgement which is based on continual experienced observation. Mitsubishi Heavy Industries (MHI) has been developing a comprehensive data management and diagnosis system, which continuously observes the secondary water chemistry data with on-line monitors, immediately diagnosing causes whenever any symptoms of abnormality are detected and does the necessary data management, in order to support plant staff to controll water chemistry. This system has the following three basic functions: data management, diagnosis and simulation. This paper presents the outline of the total system, and then describes in detail the procedure of diagnosis, the structure of the knowledge and its validation process

  8. Innovation Developments of Coal Chemistry Science in L.M. Litvinenko Institute of Physical-Organic Chemistry and Coal Chemistry of NAS of Ukraine

    Directory of Open Access Journals (Sweden)

    Shendrik, T.G.

    2015-11-01

    Full Text Available The article presents short historical review and innovation developments of Coal Chemistry Department of L.M. Litvinenko Institute, NAS of Ukraine connected with coal mine exploitation problems, search for decisions toward prevention of spontaneous combustion, dust control in mines, establishing structural chemical features of coal with different genesis and stages of metamorphism with the aim to develop new methods of their modification and rational use. The methods of obtaining inexpensive sorbents from Ukrainian raw materials (including carbon containing waste are proposed. The problems of modern coal chemistry science in IPOCC of NAS of Ukraine are outlined.

  9. Translational Chemistry Meets Gluten-Related Disorders.

    Science.gov (United States)

    Lammers, Karen M; Herrera, Maria G; Dodero, Veronica I

    2018-03-01

    Gluten-related disorders are a complex group of diseases that involve the activation of the immune system triggered by the ingestion of gluten. Among these, celiac disease, with a prevalence of 1 %, is the most investigated, but recently, a new pathology, named nonceliac gluten sensitivity, was reported with a general prevalence of 7 %. Finally, there other less-prevalent gluten-related diseases such as wheat allergy, gluten ataxia, and dermatitis herpetiformis (with an overall prevalence of less than 0.1 %). As mentioned, the common molecular trigger is gluten, a complex mixture of storage proteins present in wheat, barley, and a variety of oats that are not fully degraded by humans. The most-studied protein related to disease is gliadin, present in wheat, which possesses in its sequence many pathological fragments. Despite a lot of effort to treat these disorders, the only effective method is a long-life gluten-free diet. This Review summarizes the actual knowledge of gluten-related disorders from a translational chemistry point of view. We discuss what is currently known from the literature about the interaction of gluten with the gut and the critical host responses it evokes and, finally, connect them to our current and novel molecular understanding of the supramolecular organization of gliadin and the 33-mer gliadin peptide fragment under physiological conditions.

  10. Assessment of Digoxin-Specific Fab Fragment Dosages in Digoxin Poisoning.

    Science.gov (United States)

    Nordt, Sean Patrick; Clark, Richard F; Machado, Carol; Cantrell, F Lee

    2016-01-01

    Digoxin poisoning still remains a common cause of morbidity and mortality. Fortunately, digoxin-specific Fab fragments are commercially available as an antidote. However, these Fab fragments are several thousand dollars per vial. There is a standardized formula to calculate appropriate Fab fragment dosage based on the serum digoxin concentration. This can greatly reduce the amount of Fab fragment administered. There is also an empiric dosing guideline recommending 6-10 vials be given; however, this may result in higher amounts of Fab fragments being administered than required. We performed this study to assess the amounts of digoxin-specific Fab fragments administered in the treatment of digoxin poisonings recorded in a poison control system database from January 1, 2000, to December 31, 2009, in which digoxin serum concentrations were available. This was a retrospective study of 278 patients, 107 with acute poisonings (group A) and 171 following chronic poisoning (group B). In group A, the calculated Fab dose was higher than the calculated dose based on available concentrations in 39 (36%) of group A and 15 (9%) of group B patients. The average wholesale price cost of the excessive dosages ranged from $4818 to as high as $50,589 per patient. Our data suggests that clinician education on digoxin poisoning and the use of the standardized formula to calculate the Fab dose may decrease over utilization and decrease costs associated with the administration of digoxin-specific Fab fragments in the treatment of digoxin poisonings.

  11. Chemistry control at Bruce NGS 'B' from constructed to commercial operation

    International Nuclear Information System (INIS)

    Roberts, J.G.

    1987-01-01

    Pre-operational storage chemistry and flushing of the secondary side is described. The approach devised for Bruce NGS 'B' Unit 6 was unique for an Ontario Hydro Nuclear Unit. The significance of the improved Construction installation and Quality Assurance procedures, combined with those of Operations is identified. Secondary side chemistry during both commissioning and later operation is reported. It will be shown that the application of ALARA (As Low As is Reasonably Achievable) concept has resulted in tighter chemical specifications being met

  12. Fuel Chemistry Division annual progress report for 1990

    International Nuclear Information System (INIS)

    Vaidyanathan, R.

    1993-01-01

    The progress report gives brief descriptions of the various activities of the Fuel Chemistry Division of Bhabha Atomic Research Centre, Bombay for the year 1990. The descriptions of activities are arranged under the headings: Fuel Development Chemistry, Chemistry of Actinides, Quality Control of Nuclear Fuels, and studies related to Nuclear Materials Accounting. At the end of the report, a list of papers published in journals and presented at various conferences/symposia is also given. (author). 7 figs., 52 tabs

  13. Effective Fragment Potential Method for H-Bonding: How To Obtain Parameters for Nonrigid Fragments.

    Science.gov (United States)

    Dubinets, Nikita; Slipchenko, Lyudmila V

    2017-07-20

    Accuracy of the effective fragment potential (EFP) method was explored for describing intermolecular interaction energies in three dimers with strong H-bonded interactions, formic acid, formamide, and formamidine dimers, which are a part of HBC6 database of noncovalent interactions. Monomer geometries in these dimers change significantly as a function of intermonomer separation. Several EFP schemes were considered, in which fragment parameters were prepared for a fragment in its gas-phase geometry or recomputed for each unique fragment geometry. Additionally, a scheme in which gas-phase fragment parameters are shifted according to relaxed fragment geometries is introduced and tested. EFP data are compared against the coupled cluster with single, double, and perturbative triple excitations (CCSD(T)) method in a complete basis set (CBS) and the symmetry adapted perturbation theory (SAPT). All considered EFP schemes provide a good agreement with CCSD(T)/CBS for binding energies at equilibrium separations, with discrepancies not exceeding 2 kcal/mol. However, only the schemes that utilize relaxed fragment geometries remain qualitatively correct at shorter than equilibrium intermolecular distances. The EFP scheme with shifted parameters behaves quantitatively similar to the scheme in which parameters are recomputed for each monomer geometry and thus is recommended as a computationally efficient approach for large-scale EFP simulations of flexible systems.

  14. 75 FR 63188 - Draft Guidance for Industry: Early Clinical Trials With Live Biotherapeutic Products: Chemistry...

    Science.gov (United States)

    2010-10-14

    ...] Draft Guidance for Industry: Early Clinical Trials With Live Biotherapeutic Products: Chemistry...: Chemistry, Manufacturing, and Control Information'' dated September 2010. The draft guidance provides... Products: Chemistry, Manufacturing, and Control Information'' dated September 2010. The draft guidance...

  15. Biodegradable hyaluronic acid hydrogels to control release of dexamethasone through aqueous Diels-Alder chemistry for adipose tissue engineering.

    Science.gov (United States)

    Fan, Ming; Ma, Ye; Zhang, Ziwei; Mao, Jiahui; Tan, Huaping; Hu, Xiaohong

    2015-11-01

    A robust synthetic strategy of biopolymer-based hydrogels has been developed where hyaluronic acid derivatives reacted through aqueous Diels-Alder chemistry without the involvement of chemical catalysts, allowing for control and sustain release of dexamethasone. To conjugate the hydrogel, furan and maleimide functionalized hyaluronic acid were synthesized, respectively, as well as furan functionalized dexamethasone, for the covalent immobilization. Chemical structure, gelation time, morphologies, swelling kinetics, weight loss, compressive modulus and dexamethasone release of the hydrogel system in PBS at 37°C were studied. The results demonstrated that the aqueous Diels-Alder chemistry provides an extremely selective reaction and proceeds with high efficiency for hydrogel conjugation and covalent immobilization of dexamethasone. Cell culture results showed that the dexamethasone immobilized hydrogel was noncytotoxic and preserved proliferation of entrapped human adipose-derived stem cells. This synthetic approach uniquely allows for the direct fabrication of biologically functionalized gel scaffolds with ideal structures for adipose tissue engineering, which provides a competitive alternative to conventional conjugation techniques such as copper mediated click chemistry. Copyright © 2015. Published by Elsevier B.V.

  16. Assessment of EPRI water chemistry guidelines for new nuclear power plants

    Energy Technology Data Exchange (ETDEWEB)

    Kim, K.; Fruzzetti, K.; Garcia, S. [Electric Power Research Inst., Palo Alto, California (United States); Eaker, R. [Richard W. Eaker, LLC, Matthews, North Carolina (United States); Giannelli, J.; Tangen, J. [Finetech, Inc., Parsippany, New Jersey (United States); Gorman, J.; Marks, C. [Dominion Engineering, Inc., Reston, Virginia (United States); Sawochka, S. [NWT Corp., San Jose, California (United States)

    2010-07-01

    Water chemistry control technologies for nuclear power plants have been significantly enhanced over the past few decades to improve material and equipment reliability and fuel performance, and to minimize radionuclide production and transport. Chemistry Guidelines have been developed by the Electric Power Research Institute (EPRI) for current operating plants and have been intermittently revised over the past twenty-five years for the protection of systems and components and for radiation management. As new plants are being designed for improved safety and increased power production, it is important to ensure that the designs consider implementation of industry approved water chemistry controls. In parallel, the industry will need to consider and develop updated water chemistry guidelines as well as plant startup and operational strategies based on the advanced plant designs. In 2010, EPRI began to assess chemistry control strategies at advanced plants, based on the Design Control Documents (DCDs), Combined Construction and Operating License Applications (COLA), and operating experiences (where they exist) against current Water Chemistry Guidelines. Based on this assessment, differences between planned chemistry operations at new plants and the current Guidelines will be identified. This assessment will form the basis of future activities to address these differences. The project will also assess and provide, as feasible, water chemistry guidance for startup and hot functional testing of the new plants. EPRI will initially assess the GE-Hitachi/Toshiba ABWR and the Westinghouse AP1000 designs. EPRI subsequently plans to assess other plant designs such as the AREVA U.S. EPR, Mitsubishi Heavy Industries (MHI) U.S. APWR, and GE-Hitachi (GE-H) ESBWR. This paper discusses the 2010 assessments of the ABWR and AP1000. (author)

  17. Assessment of EPRI water chemistry guidelines for new nuclear power plants

    International Nuclear Information System (INIS)

    Kim, K.; Fruzzetti, K.; Garcia, S.; Eaker, R.; Giannelli, J.; Tangen, J.; Gorman, J.; Marks, C.; Sawochka, S.

    2010-01-01

    Water chemistry control technologies for nuclear power plants have been significantly enhanced over the past few decades to improve material and equipment reliability and fuel performance, and to minimize radionuclide production and transport. Chemistry Guidelines have been developed by the Electric Power Research Institute (EPRI) for current operating plants and have been intermittently revised over the past twenty-five years for the protection of systems and components and for radiation management. As new plants are being designed for improved safety and increased power production, it is important to ensure that the designs consider implementation of industry approved water chemistry controls. In parallel, the industry will need to consider and develop updated water chemistry guidelines as well as plant startup and operational strategies based on the advanced plant designs. In 2010, EPRI began to assess chemistry control strategies at advanced plants, based on the Design Control Documents (DCDs), Combined Construction and Operating License Applications (COLA), and operating experiences (where they exist) against current Water Chemistry Guidelines. Based on this assessment, differences between planned chemistry operations at new plants and the current Guidelines will be identified. This assessment will form the basis of future activities to address these differences. The project will also assess and provide, as feasible, water chemistry guidance for startup and hot functional testing of the new plants. EPRI will initially assess the GE-Hitachi/Toshiba ABWR and the Westinghouse AP1000 designs. EPRI subsequently plans to assess other plant designs such as the AREVA U.S. EPR, Mitsubishi Heavy Industries (MHI) U.S. APWR, and GE-Hitachi (GE-H) ESBWR. This paper discusses the 2010 assessments of the ABWR and AP1000. (author)

  18. Human development VIII: a theory of "deep" quantum chemistry and cell consciousness: quantum chemistry controls genes and biochemistry to give cells and higher organisms consciousness and complex behavior.

    Science.gov (United States)

    Ventegodt, Søren; Hermansen, Tyge Dahl; Flensborg-Madsen, Trine; Nielsen, Maj Lyck; Merrick, Joav

    2006-11-14

    Deep quantum chemistry is a theory of deeply structured quantum fields carrying the biological information of the cell, making it able to remember, intend, represent the inner and outer world for comparison, understand what it "sees", and make choices on its structure, form, behavior and division. We suggest that deep quantum chemistry gives the cell consciousness and all the qualities and abilities related to consciousness. We use geometric symbolism, which is a pre-mathematical and philosophical approach to problems that cannot yet be handled mathematically. Using Occam's razor we have started with the simplest model that works; we presume this to be a many-dimensional, spiral fractal. We suggest that all the electrons of the large biological molecules' orbitals make one huge "cell-orbital", which is structured according to the spiral fractal nature of quantum fields. Consciousness of single cells, multi cellular structures as e.g. organs, multi-cellular organisms and multi-individual colonies (like ants) and human societies can thus be explained by deep quantum chemistry. When biochemical activity is strictly controlled by the quantum-mechanical super-orbital of the cell, this orbital can deliver energetic quanta as biological information, distributed through many fractal levels of the cell to guide form and behavior of an individual single or a multi-cellular organism. The top level of information is the consciousness of the cell or organism, which controls all the biochemical processes. By this speculative work inspired by Penrose and Hameroff we hope to inspire other researchers to formulate more strict and mathematically correct hypothesis on the complex and coherence nature of matter, life and consciousness.

  19. Carboxyl-terminal parathyroid hormone fragments: role in parathyroid hormone physiopathology.

    Science.gov (United States)

    D'Amour, Pierre; Brossard, Jean-Hugues

    2005-07-01

    Carboxyl-terminal parathyroid hormone (C-PTH) fragments constitute 80% of circulating PTH. Since the first 34 amino acids of the PTH structure are sufficient to explain PTH classical biological effects on the type I PTH/PTHrP receptor and since C-PTH fragments do not bind to this receptor, they have long been considered inactive. Recent data suggest the existence of a C-PTH receptor through which C-PTH fragments exert biological effects opposite to those of human PTH(1-84) on the type I PTH/PTHrP receptor. This is why a lot of attention has been paid to these fragments recently. In vivo, synthetic C-PTH fragments are able to decrease calcium concentration, to antagonize the calcemic response to human PTH(1-34) and human PTH(1-84) and to decrease the high bone turnover rate induced by human PTH(1-84). In vitro, they inhibit bone resorption, promote osteocyte apoptosis and exert a variety of effects on bone and cartilaginous cells. These effects are opposite to those of human PTH(1-84) on the PTH/PTHrP type I receptor. This suggests that the molecular forms of circulating PTH may control bone participation in calcium homeostasis via two different receptors. Clinically, the accumulation of C-PTH fragments in renal failure patients may cause PTH resistance and may be associated with adynamic bone disease. Rare parathyroid tumors, without a set point error, overproduce C-PTH fragments. The implication of C-PTH fragments in osteoporosis is still to be explored. C-PTH fragments represent a new field of investigation in PTH biology. More studies are necessary to disclose their real importance in calcium and bone homeostasis in health and disease.

  20. Robust Object Tracking Using Valid Fragments Selection.

    Science.gov (United States)

    Zheng, Jin; Li, Bo; Tian, Peng; Luo, Gang

    Local features are widely used in visual tracking to improve robustness in cases of partial occlusion, deformation and rotation. This paper proposes a local fragment-based object tracking algorithm. Unlike many existing fragment-based algorithms that allocate the weights to each fragment, this method firstly defines discrimination and uniqueness for local fragment, and builds an automatic pre-selection of useful fragments for tracking. Then, a Harris-SIFT filter is used to choose the current valid fragments, excluding occluded or highly deformed fragments. Based on those valid fragments, fragment-based color histogram provides a structured and effective description for the object. Finally, the object is tracked using a valid fragment template combining the displacement constraint and similarity of each valid fragment. The object template is updated by fusing feature similarity and valid fragments, which is scale-adaptive and robust to partial occlusion. The experimental results show that the proposed algorithm is accurate and robust in challenging scenarios.

  1. Chemistry and physics

    International Nuclear Information System (INIS)

    Broerse, J.J.; Barendsen, G.W.; Kal, H.B.; Kogel, A.J. van der

    1983-01-01

    This book contains the extended abstracts of the contributions of the poster workshop sessions on chemistry and physics of the 7th international congress of radiation research. They cover the following main topics: primary processes in radiation physics and chemistry, general chemistry in radiation chemistry, DNA and model systems in radiation chemistry, molecules of biological interest in radiation chemistry, techniques in radiation chemistry, hot atom chemistry. refs.; figs.; tabs

  2. Water chemistry technology. One of the key technologies for safe and reliable nuclear power plant operation

    International Nuclear Information System (INIS)

    Uchida, Shunsuke; Katsumura, Yosuke

    2013-01-01

    Water chemistry control is one of the key technologies to establish safe and reliable operation of nuclear power plants. Continuous and collaborative efforts of plant manufacturers and plant operator utilities have been focused on optimal water chemistry control, for which, a trio of requirements for water chemistry should be simultaneously satisfied: (1) better reliability of reactor structures and fuel rods; (2) lower occupational exposure and (3) fewer radwaste sources. Various groups in academia have carried out basic research to support the technical bases of water chemistry in plants. The Research Committee on Water Chemistry of the Atomic Energy Society of Japan (AESJ), which has now been reorganized as the Division of Water Chemistry (DWC) of AESJ, has played important roles to promote improvements in water chemistry control, to share knowledge about and experiences with water chemistry control among plant operators and manufacturers and to establish common technological bases for plant water chemistry and then to transfer them to the next generation of plant workers engaged in water chemistry. Furthermore, the DWC has tried and succeeded arranging R and D proposals for further improvement in water chemistry control through roadmap planning. In the paper, major achievements in plant technologies and in basic research studies of water chemistry in Japan are reviewed. The contributions of the DWC to the long-term safe management of the damaged reactors at the Fukushima Daiichi Nuclear Power Plant until their decommissioning are introduced. (author)

  3. Coolant Chemistry Control: Oxygen Mass Transport in Lead Bismuth Eutectic

    International Nuclear Information System (INIS)

    Weisenburger, A.; Mueller, G.; Bruzzese, C.; Glass, A.

    2015-01-01

    In lead-bismuth cooled transmutation systems, oxygen, dissolved in the coolant at defined quantities, is required for stable long-term operation by assuring the formation of protective oxide scales on structural steel surfaces. Extracted oxygen must be permanently delivered to the system and distributed in the entire core. Therefore, coolant chemistry control involves detailed knowledge on oxygen mass transport. Beside the different flow regimes a core might have stagnant areas at which oxygen delivery can only be realised by diffusion. The difference between oxygen transport in flow paths and in stagnant zones is one of the targets of such experiments. To investigate oxygen mass transport in flowing and stagnant conditions, a dedicated facility was designed based on computational fluid dynamics (CFD). CFD also was applied to define the position of oxygen sensors and ultrasonic Doppler velocimetry transducers for flow measurements. This contribution will present the test facility, design relevant CFD calculations and results of first tests performed. (authors)

  4. User's guide for vectorized code EQUIL for calculating equilibrium chemistry on Control Data STAR-100 computer

    Science.gov (United States)

    Kumar, A.; Graves, R. A., Jr.; Weilmuenster, K. J.

    1980-01-01

    A vectorized code, EQUIL, was developed for calculating the equilibrium chemistry of a reacting gas mixture on the Control Data STAR-100 computer. The code provides species mole fractions, mass fractions, and thermodynamic and transport properties of the mixture for given temperature, pressure, and elemental mass fractions. The code is set up for the electrons H, He, C, O, N system of elements. In all, 24 chemical species are included.

  5. Description and principles of use of an automatic control device usable, in particular, in analytical chemistry

    International Nuclear Information System (INIS)

    Rigaudiere, Roger; Jeanmaire, Lucien

    1969-01-01

    This note describes an automatic control device for the programming of about 20 different functions, chronologically and during a given time. Any voltage can be chosen at the output to perform the different functions. Three examples of utilisation taken in analytical chemistry are given to illustrate the possibilities offered by this device, but its domain of use is much more universal and independent of the type of functions [fr

  6. Optimization long hole blast fragmentation techniques and detonating circuit underground uranium mine stope

    International Nuclear Information System (INIS)

    Li Qin; Yang Lizhi; Song Lixia; Qin De'en; Xue Yongshe; Wang Zhipeng

    2012-01-01

    Aim at high rate of large blast fragmentation, a big difficulty in long hole drilling and blasting underground uranium mine stope, it is pointed out at the same time of taking integrated technical management measures, the key is to optimize the drilling and blasting parameters and insure safety the act of one that primes, adopt 'minimum burden' blasting technique, renew the stope fragmentation process, and use new process of hole bottom indirect initiation fragmentation; optimize the detonating circuit and use safe, reliable and economically rational duplex non-electric detonating circuit. The production practice shows that under the guarantee of strictly controlled construction quality, the application of optimized blast fragmentation technique has enhanced the reliability of safety detonation and preferably solved the problem of high rate of large blast fragments. (authors)

  7. Self-organized criticality in fragmenting

    DEFF Research Database (Denmark)

    Oddershede, L.; Dimon, P.; Bohr, J.

    1993-01-01

    The measured mass distributions of fragments from 26 fractured objects of gypsum, soap, stearic paraffin, and potato show evidence of obeying scaling laws; this suggests the possibility of self-organized criticality in fragmenting. The probability of finding a fragment scales inversely to a power...

  8. Water chemistry controlled aggregation and photo-transformation of silver nanoparticles in environmental waters.

    Science.gov (United States)

    Yin, Yongguang; Yang, Xiaoya; Zhou, Xiaoxia; Wang, Weidong; Yu, Sujuan; Liu, Jingfu; Jiang, Guibin

    2015-08-01

    The inevitable release of engineered silver nanoparticles (AgNPs) into aquatic environments has drawn great concerns about its environmental toxicity and safety. Although aggregation and transformation play crucial roles in the transport and toxicity of AgNPs, how the water chemistry of environmental waters influences the aggregation and transformation of engineered AgNPs is still not well understood. In this study, the aggregation of polyvinylpyrrolidone (PVP) coated AgNPs was investigated in eight typical environmental water samples (with different ionic strengths, hardness, and dissolved organic matter (DOM) concentrations) by using UV-visible spectroscopy and dynamic light scattering. Raman spectroscopy was applied to probe the interaction of DOM with the surface of AgNPs. Further, the photo-transformation and morphology changes of AgNPs in environmental waters were studied by UV-visible spectroscopy, inductively coupled plasma mass spectrometry, and transmission electron microscopy. The results suggested that both electrolytes (especially Ca(2+) and Mg(2+)) and DOM in the surface waters are key parameters for AgNP aggregation, and sunlight could accelerate the morphology change, aggregation, and further sedimentation of AgNPs. This water chemistry controlled aggregation and photo-transformation should have significant environmental impacts on the transport and toxicity of AgNPs in the aquatic environments. Copyright © 2015. Published by Elsevier B.V.

  9. Water chemistry experience of nuclear power plants in Japan

    International Nuclear Information System (INIS)

    Ishigure, Kenkichi; Abe, Kenji; Nakajima, Nobuo; Nagao, Hiroyuki; Uchida, Shunsuke.

    1989-01-01

    Japanese LWRs have experienced several troubles caused by corrosions of structural materials in the past ca. 20 years of their operational history, among which are increase in the occupational radiation exposures, intergranular stress corrosion cracking (IGSCC) of stainless steel piping in BWR, and steam generator corrosion problems in PWR. These problems arised partly from the improper operation of water chemistry control of reactor coolant systems. Consequently, it has been realized that water chemistry control is one of the most important factors to attain high availability and reliability of LWR, and extensive researches and developments have been conducted in Japan to achieve the optimum water chemistry control, which include the basic laboratory experiments, analyses of plant operational data, loop tests in operating plants and computer code developments. As a result of the continuing efforts, the Japanese LWR plants have currently attained a very high performance in their operation with high availability and low occupational radiation exposures. A brief review is given here on the R and D of water chemistry in Japan. (author)

  10. Antiparallel Dynamic Covalent Chemistries

    NARCIS (Netherlands)

    Matysiak, Bartosz M.; Nowak, Piotr; Cvrtila, Ivica; Pappas, Charalampos G.; Liu, Bin; Komaromy, David; Otto, Sijbren

    2017-01-01

    The ability to design reaction networks with high, but addressable complexity is a necessary prerequisite to make advanced functional chemical systems. Dynamic combinatorial chemistry has, proven to be a useful tool in achieving complexity, however with some limitations in controlling it. Herein we

  11. Radioanalytical Chemistry for Automated Nuclear Waste Process Monitoring

    International Nuclear Information System (INIS)

    Egorov, Oleg B.; Grate, Jay W.; DeVol, Timothy A.

    2003-01-01

    This research program is directed toward rapid, sensitive, and selective determination of beta and alpha-emitting radionuclides such as 99Tc, 90Sr, and trans-uranium (TRU) elements in low activity waste (LAW) processing streams. The overall technical approach is based on automated radiochemical measurement principles. Nuclear waste process streams are particularly challenging for rapid analytical methods due to the complex, high- ionic-strength, caustic brine sample matrix, the presence of interfering radionuclides, and the variable and uncertain speciation of the radionuclides of interest. As a result, matrix modification, speciation control, and separation chemistries are required for use in automated process analyzers. Significant knowledge gaps exist relative to the design of chemistries for such analyzers so that radionuclides can be quantitatively and rapidly separated and analyzed in solutions derived from low-activity waste processing operations. This research is addressing these knowledge gaps in the area of separation science, nuclear detection, and analytical chemistry and instrumentation. The outcome of these investigations will be the knowledge necessary to choose appropriate chemistries for sample matrix modification and analyte speciation control and chemistries for rapid and selective separation and preconcentration of target radionuclides from complex sample matrices. In addition, new approaches for quantification of alpha emitters in solution using solid state diode detectors, as well as improved instrumentation and signal processing techniques for use with solid-state and scintillation detectors, will be developed. New knowledge of the performance of separation materials, matrix modification and speciation control chemistries, instrument configurations, and quantitative analytical approaches will provide the basis for designing effective instrumentation for radioanalytical process monitoring. Specific analytical targets include 99 Tc, 90Sr and

  12. Organic chemistry as a language and the implications of chemical linguistics for structural and retrosynthetic analyses.

    Science.gov (United States)

    Cadeddu, Andrea; Wylie, Elizabeth K; Jurczak, Janusz; Wampler-Doty, Matthew; Grzybowski, Bartosz A

    2014-07-28

    Methods of computational linguistics are used to demonstrate that a natural language such as English and organic chemistry have the same structure in terms of the frequency of, respectively, text fragments and molecular fragments. This quantitative correspondence suggests that it is possible to extend the methods of computational corpus linguistics to the analysis of organic molecules. It is shown that within organic molecules bonds that have highest information content are the ones that 1) define repeat/symmetry subunits and 2) in asymmetric molecules, define the loci of potential retrosynthetic disconnections. Linguistics-based analysis appears well-suited to the analysis of complex structural and reactivity patterns within organic molecules. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Energy production using fission fragment rockets

    International Nuclear Information System (INIS)

    Chapline, G.; Matsuda, Y.

    1991-08-01

    Fission fragment rockets are nuclear reactors with a core consisting of thin fibers in a vacuum, and which use magnetic fields to extract the fission fragments from the reactor core. As an alternative to ordinary nuclear reactors, fission fragment rockets would have the following advantages: Approximately twice as efficient if one can directly convert the fission fragment energy into electricity; by reducing the buildup of a fission fragment inventory in the reactor one could avoid a Chernobyl type disaster; and collecting the fission fragments outside the reactor could simplify the waste disposal problem. 6 refs., 4 figs., 2 tabs

  14. Smart Surface Chemistries of Conducting Polymers

    DEFF Research Database (Denmark)

    Lind, Johan Ulrik

    In this thesis we investigate post-polymerization covalent modifications of poly(3,4-dioxythiophene (PEDOT)-type conducting polymers. The aim of the modifications is to gain specific control of the interaction between the material and living mammalian cells. The use of “click-chemistry” to modify...... a straightforward and in-expensive method for patterning conducting polymer thin films into microelectrodes, without losing control of the surface chemistry of the samples. On the contrary, the method provides direct control of the surface chemistry of both the fabricated micro-electrodes and the gaps between them....... The method is based on locally removing PEDOTtype polymers to expose underlying non-conducting functional polymer substrates. Thereby, multifunctional substrates are obtained. By applying this method, we are able to fabricate allpolymer micro-systems with multiple types of localized functional (bio...

  15. Fragmentation of relativistic nuclei

    International Nuclear Information System (INIS)

    Cork, B.

    1975-06-01

    Nuclei with energies of several GeV/n interact with hadrons and produce fragments that encompass the fields of nuclear physics, meson physics, and particle physics. Experimental results are now available to explore problems in nuclear physics such as the validity of the shell model to explain the momentum distribution of fragments, the contribution of giant dipole resonances to fragment production cross sections, the effective Coulomb barrier, and nuclear temperatures. A new approach to meson physics is possible by exploring the nucleon charge-exchange process. Particle physics problems are explored by measuring the energy and target dependence of isotope production cross sections, thus determining if limiting fragmentation and target factorization are valid, and measuring total cross sections to determine if the factorization relation, sigma/sub AB/ 2 = sigma/sub AA/ . sigma/sub BB/, is violated. Also, new experiments have been done to measure the angular distribution of fragments that could be explained as nuclear shock waves, and to explore for ultradense matter produced by very heavy ions incident on heavy atoms. (12 figures, 2 tables)

  16. Detection of fission fragments by secondary emission; Detection des fragments de fission par emission secondaire

    Energy Technology Data Exchange (ETDEWEB)

    Audias, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    This fission fragment detecting apparatus is based on the principle that fragments traversing a thin foil will cause emission of secondary electrons. These electrons are then accelerated (10 kV) and directly detected by means of a plastic scintillator and associated photomultiplier. Some of the advantages of such a detector are, its rapidity, its discriminating power between alpha particles and fission fragments, its small energy loss in detecting the fragments and the relatively great amount of fissionable material which it can contain. This paper is subdivided as follows: a) theoretical considerations b) constructional details of apparatus and some experimental details and c) a study of the secondary emission effect itself. (author) [French] Le detecteur de fragments de fission que nous avons realise est base sur le principe de l'emission secondaire produite par les fragments de fission traversant une feuille mince: les electrons secondaires emis sont acceleres a des tensions telles (de l'ordre de 10 kV), qu'ils soient directement detectables par un scintillateur plastique associe a un photomultiplicateur. L'interet d'un tel detecteur reside: dans sa rapidite, sa tres bonne discrimination alpha, fission, la possibilite de detecter les fragments de fission avec une perte d'energie pouvant rester relativement faible, et la possibilite d'introduire des quantites de matiere fissile plus importantes que dans les autres types de detecteurs. Ce travail comporte: -) un apercu bibliographique de la theorie du phenomene, -) realisation et mise au point du detecteur avec etude experimentale de quelques parametres intervenant dans l'emission secondaire, -) etude de l'emission secondaire (sur la face d'emergence des fragments de fission) en fonction de l'energie du fragment et en fonction de l'epaisseur de matiere traversee avant emission secondaire, et -) une etude comparative de l'emission secondaire sur la face d'incidence et sur la face d'emergence des fragments de

  17. Optimum Water Chemistry in radiation field buildup control

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chien, C. [Vallecitos Nuclear Center, Pleasanton, CA (United States)

    1995-03-01

    Nuclear utilities continue to face the challenGE of reducing exposure of plant maintenance personnel. GE Nuclear Energy has developed the concept of Optimum Water Chemistry (OWC) to reduce the radiation field buildup and minimize the radioactive waste production. It is believed that reduction of radioactive sources and improvement of the water chemistry quality should significantly reduce both the radiation exposure and radwaste production. The most important source of radioactivity is cobalt and replacement of cobalt containing alloy in the core region as well as in the entire primary system is considered the first priority to achieve the goal of low exposure and minimized waste production. A plant specific computerized cobalt transport model has been developed to evaluate various options in a BWR system under specific conditions. Reduction of iron input and maintaining low ionic impurities in the coolant have been identified as two major tasks for operators. Addition of depleted zinc is a proven technique to reduce Co-60 in reactor water and on out-of-core piping surfaces. The effect of HWC on Co-60 transport in the primary system will also be discussed.

  18. Combustion chemistry - activities in the CHEK research programme

    Energy Technology Data Exchange (ETDEWEB)

    Dam-Johansen, K.; Johnsson, J.E.; Glarborg, P.; Frandsen, F.; Jensen, A.; Oestberg, M. [Technical Univ. of Denmark, Lyngby (Denmark). Dept. of Chemical Engineering

    1997-10-01

    The combustion chemistry in the oxidation of fossil fuels and biofuels determines together with mixing and heat transfer the required size of a furnace, the emission of gaseous pollutants, and the formation of ash and deposits on surfaces. This presentation describes technologies for solid fuels combustion and gives a summary of the fuels, the pollutant chemistry and the inorganic chemistry in combustion processes. Emphasis is put on the work carried out in the CHEC (Combustion and Harmful Emission Control) Research Programme. (orig.)

  19. Diverse responses of species to landscape fragmentation in a simple food chain.

    Science.gov (United States)

    Liao, Jinbao; Bearup, Daniel; Blasius, Bernd

    2017-09-01

    Habitat destruction, characterized by habitat loss and fragmentation, is a key driver of species extinction in spatial extended communities. Recently, there has been some progress in the theory of spatial food webs, however to date practically little is known about how habitat configurational fragmentation influences multi-trophic food web dynamics. To explore how habitat fragmentation affects species persistence in food webs, we introduce a modelling framework that describes the site occupancy of species in a tri-trophic system. We assume that species dispersal range increases with trophic level, exploiting pair-approximation techniques to describe the effect of habitat clustering. In accordance with the trophic rank hypothesis, both habitat loss and fragmentation generally cause species extinction, with stronger effects occurring at higher trophic levels. However, species display diverse responses (negative, neutral or positive) to habitat loss and fragmentation separately, depending on their dispersal range and trophic position. Counter-intuitively, prey species may benefit from habitat loss due to a release in top-down control. Similarly, habitat fragmentation has almost no influence on the site occupancy of the intermediate consumer in the tri-trophic system, though it decreases those of both basal species and top predator. Consequently, species' responses to habitat destruction vary as other species become extinct. Our results reiterate the importance of the interplay between bottom-up and top-down control in trophically linked communities, and highlight the complex responses occurring in even a simple food chain. © 2017 The Authors. Journal of Animal Ecology © 2017 British Ecological Society.

  20. The dual role of fragments in fragment-assembly methods for de novo protein structure prediction

    Science.gov (United States)

    Handl, Julia; Knowles, Joshua; Vernon, Robert; Baker, David; Lovell, Simon C.

    2013-01-01

    In fragment-assembly techniques for protein structure prediction, models of protein structure are assembled from fragments of known protein structures. This process is typically guided by a knowledge-based energy function and uses a heuristic optimization method. The fragments play two important roles in this process: they define the set of structural parameters available, and they also assume the role of the main variation operators that are used by the optimiser. Previous analysis has typically focused on the first of these roles. In particular, the relationship between local amino acid sequence and local protein structure has been studied by a range of authors. The correlation between the two has been shown to vary with the window length considered, and the results of these analyses have informed directly the choice of fragment length in state-of-the-art prediction techniques. Here, we focus on the second role of fragments and aim to determine the effect of fragment length from an optimization perspective. We use theoretical analyses to reveal how the size and structure of the search space changes as a function of insertion length. Furthermore, empirical analyses are used to explore additional ways in which the size of the fragment insertion influences the search both in a simulation model and for the fragment-assembly technique, Rosetta. PMID:22095594

  1. From hot atom chemistry to epithermal chemistry

    International Nuclear Information System (INIS)

    Roessler, K.

    2004-01-01

    The rise and fall of hot atom chemistry (HAC) over the years from 1934 to 2004 is reviewed. Several applications are discussed, in particular to astrophysics and the interaction of energetic ions and atoms in space. Epithermal chemistry (ETC) is proposed to substitute the old name, since it better fits the energy range as well as the non-thermal and non-equilibrium character of the reactions. ETC also avoids the strong connexion of HAC to nuclear chemistry and stands for the opening of the field to physical chemistry and astrophysics. (orig.)

  2. Models of fragmentation with composite power laws

    Science.gov (United States)

    Tavassoli, Z.; Rodgers, G. J.

    1999-06-01

    Some models for binary fragmentation are introduced in which a time dependent transition size produces two regions of fragment sizes above and below the transition size. In the first model we assume a fixed rate of fragmentation for the largest fragment and two different rates of fragmentation in the two regions of sizes above and below the transition size. The model is solved exactly in the long time limit to reveal stable time-invariant solutions for the fragment size and mass distributions. These solutions exhibit composite power law behaviours; power laws with two different exponents for fragments in smaller and larger regions. A special case of the model with no fragmentation in the smaller size region is also examined. Another model is also introduced which have three regions of fragment sizes with different rates of fragmentation. The similarities between the stable distributions in our models and composite power law distributions from experimental work on shock fragmentation of long thin glass rods and thick clay plates are discussed.

  3. Mathematical Chemistry

    OpenAIRE

    Trinajstić, Nenad; Gutman, Ivan

    2002-01-01

    A brief description is given of the historical development of mathematics and chemistry. A path leading to the meeting of these two sciences is described. An attempt is made to define mathematical chemistry, and journals containing the term mathematical chemistry in their titles are noted. In conclusion, the statement is made that although chemistry is an experimental science aimed at preparing new compounds and materials, mathematics is very useful in chemistry, among other things, to produc...

  4. Kinetics of fragmentation-annihilation processes

    OpenAIRE

    Filipe, JAN; Rodgers, GJ

    1996-01-01

    We investigate the kinetics of systems in which particles of one species undergo binary fragmentation and pair annihilation. In the latter, nonlinear process, fragments react at collision to produce an inert species, causing loss of mass. We analyze these systems in the reaction-limited regime by solving a continuous model within the mean-field approximation. The rate of fragmentation for a particle of mass x to break into fragments of masses y and x-y has the form x(lambda-1) (lambda > 0), a...

  5. Lead bullet fragments in venison from rifle-killed deer: potential for human dietary exposure.

    Directory of Open Access Journals (Sweden)

    W Grainger Hunt

    Full Text Available Human consumers of wildlife killed with lead ammunition may be exposed to health risks associated with lead ingestion. This hypothesis is based on published studies showing elevated blood lead concentrations in subsistence hunter populations, retention of ammunition residues in the tissues of hunter-killed animals, and systemic, cognitive, and behavioral disorders associated with human lead body burdens once considered safe. Our objective was to determine the incidence and bioavailability of lead bullet fragments in hunter-killed venison, a widely-eaten food among hunters and their families. We radiographed 30 eviscerated carcasses of White-tailed Deer (Odocoileus virginianus shot by hunters with standard lead-core, copper-jacketed bullets under normal hunting conditions. All carcasses showed metal fragments (geometric mean = 136 fragments, range = 15-409 and widespread fragment dispersion. We took each carcass to a separate meat processor and fluoroscopically scanned the resulting meat packages; fluoroscopy revealed metal fragments in the ground meat packages of 24 (80% of the 30 deer; 32% of 234 ground meat packages contained at least one fragment. Fragments were identified as lead by ICP in 93% of 27 samples. Isotope ratios of lead in meat matched the ratios of bullets, and differed from background lead in bone. We fed fragment-containing venison to four pigs to test bioavailability; four controls received venison without fragments from the same deer. Mean blood lead concentrations in pigs peaked at 2.29 microg/dL (maximum 3.8 microg/dL 2 days following ingestion of fragment-containing venison, significantly higher than the 0.63 microg/dL averaged by controls. We conclude that people risk exposure to bioavailable lead from bullet fragments when they eat venison from deer killed with standard lead-based rifle bullets and processed under normal procedures. At risk in the U.S. are some ten million hunters, their families, and low

  6. Fission fragment spins and spectroscopy

    International Nuclear Information System (INIS)

    Durell, J.L.

    1988-01-01

    Prompt γ-ray coincidence experiments have been carried out on γ-rays emitted from post-neutron emission fission fragments produced by the aup 19F + 197 Au and 18 O + 232 Th reactions. Decay schemes have been established for even-even nuclei ranging from 78 Se to 148 Nd. Many new states with spin up to ∼ 12h have been observed. Apart from providing a wealth of new information on the spectroscopy of neutron-rich nuclei, the data have been analyzed to determine the average spin of primary fission fragments as a function of fragment mass. The results suggest that the fragment spins are determined by the temperature and shape of the primary fragments at or near to scission

  7. The Hitchhiker's Guide to Flow Chemistry ∥.

    Science.gov (United States)

    Plutschack, Matthew B; Pieber, Bartholomäus; Gilmore, Kerry; Seeberger, Peter H

    2017-09-27

    Flow chemistry involves the use of channels or tubing to conduct a reaction in a continuous stream rather than in a flask. Flow equipment provides chemists with unique control over reaction parameters enhancing reactivity or in some cases enabling new reactions. This relatively young technology has received a remarkable amount of attention in the past decade with many reports on what can be done in flow. Until recently, however, the question, "Should we do this in flow?" has merely been an afterthought. This review introduces readers to the basic principles and fundamentals of flow chemistry and critically discusses recent flow chemistry accounts.

  8. Organic Chemistry Students' Fragmented Ideas about the Structure and Function of Nucleophiles and Electrophiles: A Concept Map Analysis

    Science.gov (United States)

    Anzovino, Mary E.; Bretz, Stacey Lowery

    2016-01-01

    Organic chemistry students struggle with multiple aspects of reaction mechanisms and the curved arrow notation used by organic chemists. Many faculty believe that an understanding of nucleophiles and electrophiles, among other concepts, is required before students can develop fluency with the electronpushing formalism (EPF). An expert concept map…

  9. Using Gas-Phase Guest-Host Chemistry to Probe the Structures of b Ions of Peptides

    Science.gov (United States)

    Somogyi, Árpád; Harrison, Alex G.; Paizs, Béla

    2012-12-01

    Middle-sized b n ( n ≥ 5) fragments of protonated peptides undergo selective complex formation with ammonia under experimental conditions typically used to probe hydrogen-deuterium exchange in Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS). Other usual peptide fragments like y, a, a*, etc., and small b n ( n ≤ 4) fragments do not form stable ammonia adducts. We propose that complex formation of b n ions with ammonia is characteristic to macrocyclic isomers of these fragments. Experiments on a protonated cyclic peptide and N-terminal acetylated peptides fully support this hypothesis; the protonated cyclic peptide does form ammonia adducts while linear b n ions of acetylated peptides do not undergo complexation. Density functional theory (DFT) calculations on the proton-bound dimers of all-Ala b 4 , b 5 , and b 7 ions and ammonia indicate that the ionizing proton initially located on the peptide fragment transfers to ammonia upon adduct formation. The ammonium ion is then solvated by N+-H…O H-bonds; this stabilization is much stronger for macrocyclic b n isomers due to the stable cage-like structure formed and entropy effects. The present study demonstrates that gas-phase guest-host chemistry can be used to selectively probe structural features (i.e., macrocyclic or linear) of fragments of protonated peptides. Stable ammonia adducts of b 9 , b 9 -A, and b 9 -2A of A8YA, and b 13 of A20YVFL are observed indicating that even these large b-type ions form macrocyclic structures.

  10. Fragmentation of atomic clusters: A theoretical study

    International Nuclear Information System (INIS)

    Lopez, M.J.; Jellinek, J.

    1994-01-01

    Collisionless fragmentation of nonrotating model n-atom metal clusters (n=12, 13, and 14) is studied using isoergic molecular-dynamics simulations. Minimum-energy paths for fragmentation are mapped out as functions of the distance between the centers of mass of the fragments. These paths provide information on the fragmentation energies for the different fragmentation channels. Fragmentation patterns (distributions of the fragmentation channel probabilities) and global and channel-specific fragmentation rate constants are computed and analyzed as functions of the internal energy and of the size of the clusters. The trends derived from the dynamics are compared with those obtained using the RRK and TST statistical approaches. The dynamics of the fragmentation process is analyzed in terms of characteristic quantities such as the distance between the centers of mass of the fragments, their relative translational energy, and their interaction energy, all considered as functions of time

  11. The Y4-RNA fragment, a potential diagnostic marker, exists in saliva

    Directory of Open Access Journals (Sweden)

    Tatsuya Ishikawa

    2017-06-01

    Full Text Available The 94-nt full-length Y4-RNA is thought to have roles in the initiation of DNA replication and RNA quality control. Although its 31/32-nt fragment also exists abundantly in plasma, little is known about its physiological role. Since the 31/32-nt Y4-RNA fragment in sera is reported to be more abundant in patients with coronary artery disease than healthy persons, the fragment may have a potential for a diagnostic and/or prognostic biomarker for some diseases regardless of its functionality. As a step toward further investigation of its potential utility, we examined if the 31/32-nt Y4-RNA fragment also exists in saliva that can be obtained noninvasively, and showed that, in addition to the 31/32-nt fragment, 14- and 11-nt Y4-RNA fragments are present in all saliva RNA samples from four healthy persons. We established a PCR method to accurately quantitate the amount of the 31/32-nt Y4-RNA fragment, and estimated its amount in saliva of healthy persons to be 0.06 ± 0.04 fmol per nanogram of saliva RNA. We also tried to develop an easier quantitation method using a DNA molecular beacon. Keywords: Y4-RNA fragment, Saliva RNA, Diagnostic/prognostic marker, Next-generation sequencing, RT-PCR, Molecular beacon

  12. Design of combinatorial libraries for the exploration of virtual hits from fragment space searches with LoFT.

    Science.gov (United States)

    Lessel, Uta; Wellenzohn, Bernd; Fischer, J Robert; Rarey, Matthias

    2012-02-27

    A case study is presented illustrating the design of a focused CDK2 library. The scaffold of the library was detected by a feature trees search in a fragment space based on reactions from combinatorial chemistry. For the design the software LoFT (Library optimizer using Feature Trees) was used. The special feature called FTMatch was applied to restrict the parts of the queries where the reagents are permitted to match. This way a 3D scoring function could be simulated. Results were compared with alternative designs by GOLD docking and ROCS 3D alignments.

  13. Combustion chemistry. Activities in the CHEC research programme

    Energy Technology Data Exchange (ETDEWEB)

    Dam-Johansen, K; Johnsson, J E; Glarborg, P; Frandsen, F; Jensen, A; Oestberg, M [Technical Univ. of Denmark, Dept. of Chemical Engineering, Lyngby (Denmark)

    1996-12-01

    The combustion chemistry in the oxidation of fossil fuels and biofuels determines together with mixing and heat transfer the required size of a furnace, the emission of gaseous pollutants, and the formation of ash and deposits on surfaces. This paper describes technologies for solid fuels combustion and gives a summary of the fuels, the pollutant chemistry and the inorganic chemistry in combustion processes. Emphasis is put on the work carried out in the CHEC (Combustion and Harmful Emission Control Research Programme). (au) 173 refs.

  14. Fuel Chemistry Division annual progress report for 1989

    International Nuclear Information System (INIS)

    Singh Mudher, K.D.

    1993-01-01

    The progress report gives a brief description of the various activities of the Fuel Chemistry Division of Bhabha Atomic Research Centre, Bombay for the year 1989. The descriptions of activities are arranged under the headings: Fuel Development Chemistry, Chemical Quality Control, Chemistry of Actinides, Sol-Gel process for the non Nuclear Ceramics and Studies related to Nuclear Material Accounting.At the end of the report, a list of papers published in journals and presented at various conferences/symposia is also given. (author). 69 tabs., 6 figs

  15. Ion chemistry of some organic molecules studied by field ionization and field desorption mass spectrometry

    International Nuclear Information System (INIS)

    Greef, J. van der.

    1980-01-01

    The chemistry of isolated ions in the gas phase is strongly dependent on the internal energy which they have required upon formation. Since also the average lifetime of an ion depends on its internal energy, ion lifetime studies have been employed for many years to obtain a better insight in the relation between the chemistry and internal energy of gas phase ions. A very powerful tool for such studies is the field ionization kinetic (FIK) method, because it can provide a time-resolved picture of decompositions of ions with lifetimes varying from 10 -11 to 10 -5 s. The FIK method has been used in combination with 2 H, 13 C and 15 N labelling for mechanistic studies on the fragmentation of some selected ionised organic molecules. (Auth.)

  16. Combining NMR and X-ray crystallography in fragment-based drug discovery: discovery of highly potent and selective BACE-1 inhibitors.

    Science.gov (United States)

    Wyss, Daniel F; Wang, Yu-Sen; Eaton, Hugh L; Strickland, Corey; Voigt, Johannes H; Zhu, Zhaoning; Stamford, Andrew W

    2012-01-01

    Fragment-based drug discovery (FBDD) has become increasingly popular over the last decade. We review here how we have used highly structure-driven fragment-based approaches to complement more traditional lead discovery to tackle high priority targets and those struggling for leads. Combining biomolecular nuclear magnetic resonance (NMR), X-ray crystallography, and molecular modeling with structure-assisted chemistry and innovative biology as an integrated approach for FBDD can solve very difficult problems, as illustrated in this chapter. Here, a successful FBDD campaign is described that has allowed the development of a clinical candidate for BACE-1, a challenging CNS drug target. Crucial to this achievement were the initial identification of a ligand-efficient isothiourea fragment through target-based NMR screening and the determination of its X-ray crystal structure in complex with BACE-1, which revealed an extensive H-bond network with the two active site aspartate residues. This detailed 3D structural information then enabled the design and validation of novel, chemically stable and accessible heterocyclic acylguanidines as aspartic acid protease inhibitor cores. Structure-assisted fragment hit-to-lead optimization yielded iminoheterocyclic BACE-1 inhibitors that possess desirable molecular properties as potential therapeutic agents to test the amyloid hypothesis of Alzheimer's disease in a clinical setting.

  17. Multicomponent Reactions in Ligation and Bioconjugation Chemistry.

    Science.gov (United States)

    Reguera, Leslie; Méndez, Yanira; Humpierre, Ana R; Valdés, Oscar; Rivera, Daniel G

    2018-05-25

    Multicomponent reactions (MCRs) encompass an exciting class of chemical transformations that have proven success in almost all fields of synthetic organic chemistry. These convergent procedures incorporate three or more reactants into a final product in one pot, thus combining high levels of complexity and diversity generation with low synthetic cost. Striking applications of these processes are found in heterocycle, peptidomimetic, and natural product syntheses. However, their potential in the preparation of large macro- and biomolecular constructs has been realized just recently. This Account describes the most relevant results of our group in the utilization of MCRs for ligation/conjugation of biomolecules along with significant contributions from other laboratories that validate the utility of this special class of bioconjugation process. Thus, MCRs have proven to be efficient in the ligation of lipids to peptides and oligosaccharides as well as the ligation of steroids, carbohydrates, and fluorescent and affinity tags to peptides and proteins. In the field of glycolipids, we highlight the power of isocyanide-based MCRs with the one-pot double lipidation of glycan fragments functionalized as either the carboxylic acid or amine. In peptide chemistry, the versatility of the multicomponent ligation strategy is demonstrated in both solution-phase lipidation protocols and solid-phase procedures enabling the simultaneous lipidation and biotinylation of peptides. In addition, we show that MCRs are powerful methods for synchronized lipidation/labeling and macrocyclization of peptides, thus accomplishing in one step what usually requires long sequences. In the realm of protein bioconjugation, MCRs have also proven to be effective in labeling, site-selective modification, immobilization, and glycoconjugation processes. For example, we illustrate a successful application of multicomponent polysaccharide-protein conjugation with the preparation of multivalent

  18. Chemistry and cosmology.

    Science.gov (United States)

    Black, John H

    2006-01-01

    The simplest elements, hydrogen and helium, offer a remarkably rich chemistry, which has controlled crucial features of the early evolution of the universe. Theoretical models of the origin of structure (stars, galaxies, clusters of galaxies, etc.) now incorporate this chemistry in some detail. In addition to the origin of structure, cosmologists are concerned with observational tests of competing world models. Primordial chemistry may give rise to some of the earliest departures from thermodynamic equilibrium in the universe. These effects may be observable as broad-band spectroscopic distortions of the cosmic background radiation, which otherwise exhibits a nearly perfect blackbody spectrum. The chemical history of the expanding universe is followed through a detailed calculation of the evolution of the abundances of H, H+, H-, H2, H2+, H3+, and other minor species. It is shown that continuous absorption by the small concentration of H- can produce a distortion in the cosmic background spectrum with a maximum at a frequency near nu/c = 9 cm-1 (wavelength 1.1 mm). The predicted effect lies only a factor of 5 below current limits. Its detection would provide an important test of our understanding of the recombination epoch of the universe.

  19. Some aspects of primary and secondary water chemistry in CANDU reactors

    International Nuclear Information System (INIS)

    LeSurf, J.E.

    1978-09-01

    A brief review of the water chemistry in various circuits of CANDU reactors is given. Then, five particular aspects of recent work are highlighted: (i) Radiation Field Growth: in-reactor and out-reactor studies have related water chemistry to corrosion product deposition on fuel sheaths and subsequent contamination of out-core surfaces. (ii) Metal Oxide Solubility: novel techniques are being used to measure the solubilities of metal oxides at primary circuit conditions. (iii) Decontamination: the use of heavy water as coolant in CANDU reactors led to the development of a unique decontamination strategy and technique, called CAN-DECON, which has attracted the attention of operators of light-water reactors. (iv) Steam Generator Corrosion: mathematical modelling of the water chemistry in the bulk and crevice regions of nuclear steam generators, supported by chemical experiments, has shown why sea water ingress from leaking condensers can be damaging, and has provided a rapid way to evaluate alternative boiler water chemistries. (v) Automatic Control of Feedwater Chemistry: on-line automatic chemical analysis and computer control of feedwater chemistry provides All Volatile Treatment for normal operation with pure feedwater, and carefully controlled sodium phosphate addition when there is detectable sea-water ingress from leaking condensers. (author)

  20. Electron-correlated fragment-molecular-orbital calculations for biomolecular and nano systems.

    Science.gov (United States)

    Tanaka, Shigenori; Mochizuki, Yuji; Komeiji, Yuto; Okiyama, Yoshio; Fukuzawa, Kaori

    2014-06-14

    Recent developments in the fragment molecular orbital (FMO) method for theoretical formulation, implementation, and application to nano and biomolecular systems are reviewed. The FMO method has enabled ab initio quantum-mechanical calculations for large molecular systems such as protein-ligand complexes at a reasonable computational cost in a parallelized way. There have been a wealth of application outcomes from the FMO method in the fields of biochemistry, medicinal chemistry and nanotechnology, in which the electron correlation effects play vital roles. With the aid of the advances in high-performance computing, the FMO method promises larger, faster, and more accurate simulations of biomolecular and related systems, including the descriptions of dynamical behaviors in solvent environments. The current status and future prospects of the FMO scheme are addressed in these contexts.

  1. PWR Secondary Water Chemistry Control Status: A Summary of Industry Initiatives, Experience and Trends Relative to the EPRI PWR Secondary Water Chemistry Guidelines

    International Nuclear Information System (INIS)

    Fruzzetti, Keith; Choi, Samuel

    2012-09-01

    The latest revision of the EPRI Pressurized Water Reactor (PWR) Secondary Water Chemistry Guidelines was issued in February 2009. The Guidelines continue to focus on minimizing stress corrosion cracking (SCC) of steam generator tubes, as well as minimizing degradation of other major components / subsystems of the secondary system. The Guidelines provide a technically-based framework for a plant-specific and effective PWR secondary water chemistry program. With the issuance of Revision 7 of the Guidelines in 2009, many plants have implemented changes that allow greater flexibility on startup. For example, the previous Guidelines (Revision 6) contained a possible low power hold at 5% power and a possible mid power hold at approximately 30% power based on chemistry constraints. Revision 7 has established a range over which a plant-specific value can be chosen for the possible low power hold (between 5% and 15%) and mid power hold (between 30% and 50%). This has provided plants the ability to establish significant plant evolutions prior to reaching the possible power hold; such as establishing seal steam to the condenser, placing feed pumps in service, or initiating forward flow of heater drains. The application of this flexibility in the industry will be explored. This paper also highlights the major initiatives and industry trends with respect to PWR secondary chemistry; and outlines the recent work to effectively address them. These will be presented in light of recent operating experience, as derived from EPRI's PWR Chemistry Monitoring and Assessment (CMA) program (which contains more than 400 cycles of operating chemistry data). (authors)

  2. A Smart Superwetting Surface with Responsivity in Both Surface Chemistry and Microstructure.

    Science.gov (United States)

    Zhang, Dongjie; Cheng, Zhongjun; Kang, Hongjun; Yu, Jianxin; Liu, Yuyan; Jiang, Lei

    2018-03-26

    Recently, smart surfaces with switchable wettability have aroused much attention. However, only single surface chemistry or the microstructure can be changed on these surfaces, which significantly limits their wetting performances, controllability, and applications. A new surface with both tunable surface microstructure and chemistry was prepared by grafting poly(N-isopropylacrylamide) onto the pillar-structured shape memory polymer on which multiple wetting states from superhydrophilicity to superhydrophobicity can be reversibly and precisely controlled by synergistically regulating the surface microstructure and chemistry. Meanwhile, based on the excellent controllability, we also showed the application of the surface as a rewritable platform, and various gradient wettings can be obtained. This work presents for the first time a surface with controllability in both surface chemistry and microstructure, which starts some new ideas for the design of novel superwetting materials. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Effect of Marijuana Smoking on Blood Chemistry and Serum ...

    African Journals Online (AJOL)

    The effect of marijuana smoking on blood chemistry and serum biogenic amines concentrations in humans was investigated. Eighty Marijuana addicts and twenty non- marijuana smokers were used in the study. Blood chemistry and serum biogenic amines concentrations of the marijuana addicts and controls, were ...

  4. DNA fragmentation in spermatozoa

    DEFF Research Database (Denmark)

    Rex, A S; Aagaard, J.; Fedder, J

    2017-01-01

    Sperm DNA Fragmentation has been extensively studied for more than a decade. In the 1940s the uniqueness of the spermatozoa protein complex which stabilizes the DNA was discovered. In the fifties and sixties, the association between unstable chromatin structure and subfertility was investigated....... In the seventies, the impact of induced DNA damage was investigated. In the 1980s the concept of sperm DNA fragmentation as related to infertility was introduced as well as the first DNA fragmentation test: the Sperm Chromatin Structure Assay (SCSA). The terminal deoxynucleotidyl transferase nick end labelling...... (TUNEL) test followed by others was introduced in the nineties. The association between DNA fragmentation in spermatozoa and pregnancy loss has been extensively investigated spurring the need for a therapeutic tool for these patients. This gave rise to an increased interest in the aetiology of DNA damage...

  5. High-voltage pulsed generator for dynamic fragmentation of rocks.

    Science.gov (United States)

    Kovalchuk, B M; Kharlov, A V; Vizir, V A; Kumpyak, V V; Zorin, V B; Kiselev, V N

    2010-10-01

    A portable high-voltage (HV) pulsed generator has been designed for rock fragmentation experiments. The generator can be used also for other technological applications. The installation consists of low voltage block, HV block, coaxial transmission line, fragmentation chamber, and control system block. Low voltage block of the generator, consisting of a primary capacitor bank (300 μF) and a thyristor switch, stores pulse energy and transfers it to the HV block. The primary capacitor bank stores energy of 600 J at the maximum charging voltage of 2 kV. HV block includes HV pulsed step up transformer, HV capacitive storage, and two electrode gas switch. The following technical parameters of the generator were achieved: output voltage up to 300 kV, voltage rise time of ∼50 ns, current amplitude of ∼6 kA with the 40 Ω active load, and ∼20 kA in a rock fragmentation regime (with discharge in a rock-water mixture). Typical operation regime is a burst of 1000 pulses with a frequency of 10 Hz. The operation process can be controlled within a wide range of parameters. The entire installation (generator, transmission line, treatment chamber, and measuring probes) is designed like a continuous Faraday's cage (complete shielding) to exclude external electromagnetic perturbations.

  6. High-voltage pulsed generator for dynamic fragmentation of rocks

    Science.gov (United States)

    Kovalchuk, B. M.; Kharlov, A. V.; Vizir, V. A.; Kumpyak, V. V.; Zorin, V. B.; Kiselev, V. N.

    2010-10-01

    A portable high-voltage (HV) pulsed generator has been designed for rock fragmentation experiments. The generator can be used also for other technological applications. The installation consists of low voltage block, HV block, coaxial transmission line, fragmentation chamber, and control system block. Low voltage block of the generator, consisting of a primary capacitor bank (300 μF) and a thyristor switch, stores pulse energy and transfers it to the HV block. The primary capacitor bank stores energy of 600 J at the maximum charging voltage of 2 kV. HV block includes HV pulsed step up transformer, HV capacitive storage, and two electrode gas switch. The following technical parameters of the generator were achieved: output voltage up to 300 kV, voltage rise time of ˜50 ns, current amplitude of ˜6 kA with the 40 Ω active load, and ˜20 kA in a rock fragmentation regime (with discharge in a rock-water mixture). Typical operation regime is a burst of 1000 pulses with a frequency of 10 Hz. The operation process can be controlled within a wide range of parameters. The entire installation (generator, transmission line, treatment chamber, and measuring probes) is designed like a continuous Faraday's cage (complete shielding) to exclude external electromagnetic perturbations.

  7. Photon-hadron fragmentation: theoretical situation

    International Nuclear Information System (INIS)

    Peschanski, R.

    1983-07-01

    Using a selection of new experimental results models of hadronic fragmentation and their phenomenological comparison are presented. Indeed a convenient theory of hadronic fragmentation -for instance based on Q.C.D.- does not exist: low transverse momentum fragmentation involves the badly known hadronic long-range forces. Models should clarify the situation in the prospect of an eventual future theory

  8. Synthesis of amphiphilic poly(ε-caprolactone)-b-poly( N-vinylcaprolactam) block copolymers via the combination of RAFT polymerization and click chemistry

    International Nuclear Information System (INIS)

    Assis, Paulo Henrique; Aguiar, Graziele Aparecida de Jesus; Moraes, Rodolfo Minto de; Medeiros, Simone de Fatima; Santos, Amilton Martins

    2016-01-01

    Full text: In recent years, well-defined block copolymers composed of a hydrophilic and hydrophobic segments have gained much interest as drug carriers, because of their enhanced solubility and sustained release of the drug in controlled delivery systems [1]. The development of strategies to obtain block copolymers has attracted considerable attention, due to the possibility to combine characteristic properties of the homopolymers. A wide variety of well-defined block copolymers have been successfully synthesized by combining the efficiency and selectivity of click chemistry with the powerful RAFT polymerization mechanism. In the present work, well-defined amphiphilic, biocompatible, partially biodegradable, and thermosensitive poly(ε-caprolactone)-b-poly(N-vinylcaprolactam) (PCL-b-PNVCL) block copolymers were synthesized by combining ring opening polymerization (ROP), reversible addition-fragmentation chain transfer (RAFT) polymerization and subsequent click chemistry reaction. Alkyne-terminated poly(ε-caprolactone) (alkyne-PCL) was obtained by the ring opening polymerization of ε-caprolactone (ε-CL) using propargyl alcohol as initiator and stannous-2-ethylhexanoate [Sn(Oct) 2 ] as catalyst. The azide end-capped-poly(N-vinylcaprolactam) (PNVCL-N 3 ) was synthesized by reversible addition-fragmentation chain transfer/macromolecular design via interchange of xanthates (RAFT/MADIX) polymerization of the N-vinylcaprolactam (NVCL) mediated by a novel chain transfer agent comprising an azide function , 2-azidoethyl[(ethoxycarbonothioyl)thio](phenyl)acetate. These functionalized homopolymers, alkyne-PCL and PNVCL-N 3 , were coupled by the 1,3 dipolar cycloaddition reaction in order to obtain the corresponding block copolymers. These (co)polymers were characterized by FTIR, 1 H NMR and GPC measurements. Reference: 1. RAMESH, K., SINGH, S., MITRA, K., CHATTOPADHYAY, D., MISRA, N., & RAY, B. (2015). Colloid and Polymer Science, 1-9. (author)

  9. Industrial chemistry engineering

    International Nuclear Information System (INIS)

    1993-01-01

    This book on industrial chemistry engineering is divided in two parts. The first part deals with industrial chemistry, inorganic industrial chemistry, organic industrial chemistry, analytical chemistry and practical questions. The last parts explain the chemical industry, a unit parts and thermodynamics in chemical industry and reference. It reveals the test subjects for the industrial chemistry engineering with a written examination and practical skill.

  10. Catalysis as a foundational pillar of green chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Anastas, Paul T. [White House Office of Science and Technology Policy, Department of Chemistry, University of Nottingham Nottingham, (United Kingdom); Kirchhoff, Mary M. [U.S. Environmental Protection Agency and Trinity College, Washington, DC (United States); Williamson, Tracy C. [U.S. Environmental Protection Agency, Washington, DC (United States)

    2001-11-30

    Catalysis is one of the fundamental pillars of green chemistry, the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances. The design and application of new catalysts and catalytic systems are simultaneously achieving the dual goals of environmental protection and economic benefit. Green chemistry, the design of chemical products and processes that reduce or eliminate the use and generation of hazardous substances, is an overarching approach that is applicable to all aspects of chemistry. From feedstocks to solvents, to synthesis and processing, green chemistry actively seeks ways to produce materials in a way that is more benign to human health and the environment. The current emphasis on green chemistry reflects a shift away from the historic 'command-and-control' approach to environmental problems that mandated waste treatment and control and clean up through regulation, and toward preventing pollution at its source. Rather than accepting waste generation and disposal as unavoidable, green chemistry seeks new technologies that are cleaner and economically competitive. Utilizing green chemistry for pollution prevention demonstrates the power and beauty of chemistry: through careful design, society can enjoy the products on which we depend while benefiting the environment. The economic benefits of green chemistry are central drivers in its advancement. Industry is adopting green chemistry methodologies because they improve the corporate bottom line. A wide array of operating costs are decreased through the use of green chemistry. When less waste is generated, environmental compliance costs go down. Treatment and disposal become unnecessary when waste is eliminated. Decreased solvent usage and fewer processing steps lessen the material and energy costs of manufacturing and increase material efficiency. The environmental, human health, and the economic advantages realized through green chemistry

  11. Recent progress on perturbative QCD fragmentation functions

    International Nuclear Information System (INIS)

    Cheung, K.

    1995-05-01

    The recent development of perturbative QCD (PQCD) fragmentation functions has strong impact on quarkonium production. I shall summarize B c meson production based on these PQCD fragmentation functions, as well as, the highlights of some recent activities on applying these PQCD fragmentation functions to explain anomalous J/ψ and ψ' production at the Tevatron. Finally, I discuss a fragmentation model based on the PQCD fragmentation functions for heavy quarks fragmenting into heavy-light mesons

  12. Fragmentation and flow in central collisions

    International Nuclear Information System (INIS)

    Jacak, B.V.; Doss, K.G.R.; Gustafsson, H.A.

    1987-01-01

    Investigation of the fragmentation mechanism requires the measurement of complicated observables. To identify what part of the reacting system gives rise to the fragments, it would be useful to tag them as participants or spectators. A large acceptance for all the reaction products and an event-by-event measurement of the fragment multiplicity is required to distinguish fragment formation via sequential emission from a large equilibrated system and multifragmentation. In order to address whether fragments are formed early or late in the collision, information about the dynamical evolution of the reaction is necessary. This can be provided by study of the global properties of the events. This paper discusses experimental techniques applicable to studying fragmentation processes. 25 refs., 8 figs

  13. Long-term effects of fragmentation and fragment properties on bird species richness in Hawaiian forests

    Science.gov (United States)

    David J. Flaspohler; Christian P. Giardina; Gregory P. Asner; Patrick Hart; Jonathan Price; Cassie Ka’apu Lyons; Xeronimo. Castaneda

    2010-01-01

    Forest fragmentation is a common disturbance affecting biological diversity, yet the impacts of fragmentation on many forest processes remain poorly understood. Forest restoration is likely to be more successful when it proceeds with an understanding of how native and exotic vertebrates utilize forest patches of different size. We used a system of forest fragments...

  14. Mass spectrometry for fragment screening.

    Science.gov (United States)

    Chan, Daniel Shiu-Hin; Whitehouse, Andrew J; Coyne, Anthony G; Abell, Chris

    2017-11-08

    Fragment-based approaches in chemical biology and drug discovery have been widely adopted worldwide in both academia and industry. Fragment hits tend to interact weakly with their targets, necessitating the use of sensitive biophysical techniques to detect their binding. Common fragment screening techniques include differential scanning fluorimetry (DSF) and ligand-observed NMR. Validation and characterization of hits is usually performed using a combination of protein-observed NMR, isothermal titration calorimetry (ITC) and X-ray crystallography. In this context, MS is a relatively underutilized technique in fragment screening for drug discovery. MS-based techniques have the advantage of high sensitivity, low sample consumption and being label-free. This review highlights recent examples of the emerging use of MS-based techniques in fragment screening. © 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

  15. Universal odd-even staggering in isotopic fragmentation and spallation cross sections of neutron-rich fragments

    Science.gov (United States)

    Mei, B.; Tu, X. L.; Wang, M.

    2018-04-01

    An evident odd-even staggering (OES) in fragment cross sections has been experimentally observed in many fragmentation and spallation reactions. However, quantitative comparisons of this OES effect in different reaction systems are still scarce for neutron-rich nuclei near the neutron drip line. By employing a third-order difference formula, the magnitudes of this OES in extensive experimental cross sections are systematically investigated for many neutron-rich nuclei with (N -Z ) from 1 to 23 over a broad range of atomic numbers (Z ≈3 -50 ). A comparison of these magnitude values extracted from fragment cross sections measured in different fragmentation and spallation reactions with a large variety of projectile-target combinations over a wide energy range reveals that the OES magnitude is almost independent of the projectile-target combinations and the projectile energy. The weighted average of these OES magnitudes derived from cross sections accurately measured in different reaction systems is adopted as the evaluation value of the OES magnitude. These evaluated OES magnitudes are recommended to be used in fragmentation and spallation models to improve their predictions for fragment cross sections.

  16. Current organic chemistry

    National Research Council Canada - National Science Library

    1997-01-01

    Provides in depth reviews on current progress in the fields of asymmetric synthesis, organometallic chemistry, bioorganic chemistry, heterocyclic chemistry, natural product chemistry, and analytical...

  17. Aquatic Chemistry

    International Nuclear Information System (INIS)

    Kim, Dong Yeun; Kim, Oh Sik; Kim, Chang Guk; Park, Cheong Gil; Lee, Gwi Hyeon; Lee, Cheol Hui

    1987-07-01

    This book deals aquatic chemistry, which treats water and environment, chemical kinetics, chemical balance like dynamical characteristic, and thermodynamics, acid-base chemistry such as summary, definition, kinetics, and PH design for mixture of acid-base chemistry, complex chemistry with definition, and kinetics, precipitation and dissolution on summary, kinetics of precipitation and dissolution, and balance design oxidation and resolution with summary, balance of oxidation and resolution.

  18. Combinatorial chemistry

    DEFF Research Database (Denmark)

    Nielsen, John

    1994-01-01

    An overview of combinatorial chemistry is presented. Combinatorial chemistry, sometimes referred to as `irrational drug design,' involves the generation of molecular diversity. The resulting chemical library is then screened for biologically active compounds.......An overview of combinatorial chemistry is presented. Combinatorial chemistry, sometimes referred to as `irrational drug design,' involves the generation of molecular diversity. The resulting chemical library is then screened for biologically active compounds....

  19. Annual Report of Institute of Nuclear Chemistry and Technology 1999

    International Nuclear Information System (INIS)

    2000-06-01

    The INCT 1999 Annual Report is the review of scientific activities in all branches being developed in the Institute of Nuclear Chemistry and Technology, Warsaw. The studies are connected in general with the following fields: radiation chemistry and physics, radiation technologies, radiochemistry, stable isotopes, nuclear analytical methods, chemistry in general, radiobiology, process engineering, material engineering, structural studies and diagnostics and nucleonic control systems and accelerators

  20. Annual Report of Institute of Nuclear Chemistry and Technology 2002

    International Nuclear Information System (INIS)

    2003-06-01

    The INCT 2002 Annual Report is the review of scientific activities in all branches being developed in the Institute of Nuclear Chemistry and Technology, Warsaw. The studies are connected in general with the following fields: radiation chemistry and physics, radiation technologies, radiochemistry, stable isotopes, nuclear analytical methods, chemistry in general, radiobiology, process engineering, material engineering, structural studies and diagnostics, nucleonic control systems and accelerators

  1. Annual Report of Institute of Nuclear Chemistry and Technology 2002

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-06-01

    The INCT 2002 Annual Report is the review of scientific activities in all branches being developed in the Institute of Nuclear Chemistry and Technology, Warsaw. The studies are connected in general with the following fields: radiation chemistry and physics, radiation technologies, radiochemistry, stable isotopes, nuclear analytical methods, chemistry in general, radiobiology, process engineering, material engineering, structural studies and diagnostics, nucleonic control systems and accelerators.

  2. Annual Report of Institute of Nuclear Chemistry and Technology 1999

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-06-01

    The INCT 1999 Annual Report is the review of scientific activities in all branches being developed in the Institute of Nuclear Chemistry and Technology, Warsaw. The studies are connected in general with the following fields: radiation chemistry and physics, radiation technologies, radiochemistry, stable isotopes, nuclear analytical methods, chemistry in general, radiobiology, process engineering, material engineering, structural studies and diagnostics and nucleonic control systems and accelerators.

  3. Forensic Chemistry

    Science.gov (United States)

    Bell, Suzanne

    2009-07-01

    Forensic chemistry is unique among chemical sciences in that its research, practice, and presentation must meet the needs of both the scientific and the legal communities. As such, forensic chemistry research is applied and derivative by nature and design, and it emphasizes metrology (the science of measurement) and validation. Forensic chemistry has moved away from its analytical roots and is incorporating a broader spectrum of chemical sciences. Existing forensic practices are being revisited as the purview of forensic chemistry extends outward from drug analysis and toxicology into such diverse areas as combustion chemistry, materials science, and pattern evidence.

  4. Physics of projectile fragments

    International Nuclear Information System (INIS)

    Minamisono, Tadanori

    1982-01-01

    This is a study report on the polarization phenomena of the projectile fragments produced by heavy ion reactions, and the beta decay of fragments. The experimental project by using heavy ions with the energy from 50 MeV/amu to 250 MeV/amu was designed. Construction of an angle-dispersion spectrograph for projectile fragments was proposed. This is a two-stage spectrograph. The first stage is a QQDQQ type separator, and the second stage is QDQD type. Estimation shows that Co-66 may be separated from the nuclei with mass of 65 and 67. The orientation of fragments can be measured by detecting beta-ray. The apparatus consists of a uniform field magnet, an energy absorber, a stopper, a RF coil and a beta-ray hodoscope. This system can be used for not only this purpose but also for the measurement of hyperfine structure. (Kato, T.)

  5. Chemistry-nuclear chemistry division. Progress report, October 1979-September 1980

    International Nuclear Information System (INIS)

    Ryan, R.R.

    1981-05-01

    This report presents the research and development programs pursued by the Chemistry-Nuclear Chemistry Division of the Los Alamos National Laboratory. Topics covered include advanced analytical methods, atmospheric chemistry and transport, biochemistry, biomedical research, element migration and fixation, inorganic chemistry, isotope separation and analysis, atomic and molecular collisions, molecular spectroscopy, muonic x rays, nuclear cosmochemistry, nuclear structure and reactions, radiochemical separations, theoretical chemistry, and unclassified weapons research

  6. Chemistry-nuclear chemistry division. Progress report, October 1979-September 1980

    Energy Technology Data Exchange (ETDEWEB)

    Ryan, R.R. (comp.)

    1981-05-01

    This report presents the research and development programs pursued by the Chemistry-Nuclear Chemistry Division of the Los Alamos National Laboratory. Topics covered include advanced analytical methods, atmospheric chemistry and transport, biochemistry, biomedical research, element migration and fixation, inorganic chemistry, isotope separation and analysis, atomic and molecular collisions, molecular spectroscopy, muonic x rays, nuclear cosmochemistry, nuclear structure and reactions, radiochemical separations, theoretical chemistry, and unclassified weapons research.

  7. Development of water chemistry diagnosis system for BWR primary loop

    International Nuclear Information System (INIS)

    Nagase, Makoto; Asakura, Yamato; Sakagami, Masaharu; Uchida, Shunsuke; Ohsumi, Katsumi.

    1988-01-01

    The prototype of a water chemistry diagnosis system for BWR primary loop has been developed. Its purposes are improvement of water chemistry control and reduction of the work burden on plant chemistry personnel. It has three main features as follows. (1) Intensifying the observation of water chemistry conditions by variable sampling intervals based on the on-line measured data. (2) Early detection of water chemistry data trends using a second order regression curve which is calculated from the measured data, and then searching the cause of anomaly if anything (3) Diagnosis of Fe concentration in feedwater using model simulations, in order to lower the radiation level in the primary system. (author)

  8. The Brazilian medicinal chemistry from 1998 to 2008 in the Journal of Medicinal Chemistry, Bioorganic and Medicinal Chemistry, Bioorganic and Medicinal Chemistry Letters and European Journal of Medicinal Chemistry [A química medicinal brasileira de 1998 a 2008 nos periódicos Journal of Medicinal Chemistry, Bioorganic and Medicinal Chemistry, Bioorganic and Medicinal Chemistry Letters e European Journal of Medicinal Chemistry

    OpenAIRE

    Bárbara Vasconcellos da Silva; Renato Saldanha Bastos; Angelo da Cunha Pinto

    2009-01-01

    In this article we present the Brazilian publications, the research groups involved, the contributions per states and the main diseases studied from 1998 to 2008 in the following periodicals: Journal of Medicinal Chemistry, Bioorganic and Medicinal Chemistry, Bioorganic and Medicinal Chemistry Letters and European Journal of Medicinal Chemistry.

  9. Quantification of DNA fragmentation in processed foods using real-time PCR.

    Science.gov (United States)

    Mano, Junichi; Nishitsuji, Yasuyuki; Kikuchi, Yosuke; Fukudome, Shin-Ichi; Hayashida, Takuya; Kawakami, Hiroyuki; Kurimoto, Youichi; Noguchi, Akio; Kondo, Kazunari; Teshima, Reiko; Takabatake, Reona; Kitta, Kazumi

    2017-07-01

    DNA analysis of processed foods is performed widely to detect various targets, such as genetically modified organisms (GMOs). Food processing often causes DNA fragmentation, which consequently affects the results of PCR analysis. In order to assess the effects of DNA fragmentation on the reliability of PCR analysis, we investigated a novel methodology to quantify the degree of DNA fragmentation. We designed four real-time PCR assays that amplified 18S ribosomal RNA gene sequences common to various plants at lengths of approximately 100, 200, 400, and 800 base pairs (bp). Then, we created an indicator value, "DNA fragmentation index (DFI)", which is calculated from the Cq values derived from the real-time PCR assays. Finally, we demonstrated the efficacy of this method for the quality control of GMO detection in processed foods by evaluating the relationship between the DFI and the limit of detection. Copyright © 2017 Elsevier Ltd. All rights reserved.

  10. Combining supramolecular chemistry with biology

    NARCIS (Netherlands)

    Uhlenheuer, D.A.; Petkau - Milroy, K.; Brunsveld, L.

    2010-01-01

    Supramolecular chemistry has primarily found its inspiration in biological molecules, such as proteins and lipids, and their interactions. Currently the supramolecular assembly of designed compounds can be controlled to great extent. This provides the opportunity to combine these synthetic

  11. MRI of displaced meniscal fragments

    International Nuclear Information System (INIS)

    Dunoski, Brian; Zbojniewicz, Andrew M.; Laor, Tal

    2012-01-01

    A torn meniscus frequently requires surgical fixation or debridement as definitive treatment. Meniscal tears with associated fragment displacement, such as bucket handle and flap tears, can be difficult to recognize and accurately describe on MRI, and displaced fragments can be challenging to identify at surgery. A displaced meniscal fragment can be obscured by synovium or be in a location not usually evaluated at arthroscopy. We present a pictorial essay of meniscal tears with displaced fragments in patients referred to a pediatric hospital in order to increase recognition and accurate interpretation by the radiologist, who in turn can help assist the surgeon in planning appropriate therapy. (orig.)

  12. MRI of displaced meniscal fragments

    Energy Technology Data Exchange (ETDEWEB)

    Dunoski, Brian [University of Cincinnati College of Medicine, Department of Radiology, Cincinnati Children' s Hospital Medical Center, Cincinnati, OH (United States); Children' s Hospital of Michigan, Department of Radiology, Detroit, MI (United States); Zbojniewicz, Andrew M.; Laor, Tal [University of Cincinnati College of Medicine, Department of Radiology, Cincinnati Children' s Hospital Medical Center, Cincinnati, OH (United States)

    2012-01-15

    A torn meniscus frequently requires surgical fixation or debridement as definitive treatment. Meniscal tears with associated fragment displacement, such as bucket handle and flap tears, can be difficult to recognize and accurately describe on MRI, and displaced fragments can be challenging to identify at surgery. A displaced meniscal fragment can be obscured by synovium or be in a location not usually evaluated at arthroscopy. We present a pictorial essay of meniscal tears with displaced fragments in patients referred to a pediatric hospital in order to increase recognition and accurate interpretation by the radiologist, who in turn can help assist the surgeon in planning appropriate therapy. (orig.)

  13. Dimensional crossover in fragmentation

    Science.gov (United States)

    Sotolongo-Costa, Oscar; Rodriguez, Arezky H.; Rodgers, G. J.

    2000-11-01

    Experiments in which thick clay plates and glass rods are fractured have revealed different behavior of fragment mass distribution function in the small and large fragment regions. In this paper we explain this behavior using non-extensive Tsallis statistics and show how the crossover between the two regions is caused by the change in the fragments’ dimensionality during the fracture process. We obtain a physical criterion for the position of this crossover and an expression for the change in the power-law exponent between the small and large fragment regions. These predictions are in good agreement with the experiments on thick clay plates.

  14. ASVCP quality assurance guidelines: control of preanalytical, analytical, and postanalytical factors for urinalysis, cytology, and clinical chemistry in veterinary laboratories.

    Science.gov (United States)

    Gunn-Christie, Rebekah G; Flatland, Bente; Friedrichs, Kristen R; Szladovits, Balazs; Harr, Kendal E; Ruotsalo, Kristiina; Knoll, Joyce S; Wamsley, Heather L; Freeman, Kathy P

    2012-03-01

    In December 2009, the American Society for Veterinary Clinical Pathology (ASVCP) Quality Assurance and Laboratory Standards committee published the updated and peer-reviewed ASVCP Quality Assurance Guidelines on the Society's website. These guidelines are intended for use by veterinary diagnostic laboratories and veterinary research laboratories that are not covered by the US Food and Drug Administration Good Laboratory Practice standards (Code of Federal Regulations Title 21, Chapter 58). The guidelines have been divided into 3 reports: (1) general analytical factors for veterinary laboratory performance and comparisons; (2) hematology, hemostasis, and crossmatching; and (3) clinical chemistry, cytology, and urinalysis. This particular report is one of 3 reports and documents recommendations for control of preanalytical, analytical, and postanalytical factors related to urinalysis, cytology, and clinical chemistry in veterinary laboratories and is adapted from sections 1.1 and 2.2 (clinical chemistry), 1.3 and 2.5 (urinalysis), 1.4 and 2.6 (cytology), and 3 (postanalytical factors important in veterinary clinical pathology) of these guidelines. These guidelines are not intended to be all-inclusive; rather, they provide minimal guidelines for quality assurance and quality control for veterinary laboratory testing and a basis for laboratories to assess their current practices, determine areas for improvement, and guide continuing professional development and education efforts. © 2012 American Society for Veterinary Clinical Pathology.

  15. Bad chemistry

    OpenAIRE

    Petsko, Gregory A

    2004-01-01

    General chemistry courses haven't changed significantly in forty years. Because most basic chemistry students are premedical students, medical schools have enormous influence and could help us start all over again to create undergraduate chemistry education that works.

  16. On-line chemistry monitoring for the secondary side

    International Nuclear Information System (INIS)

    Anon.

    1990-01-01

    Babcock and Wilcox (B and W) has developed a computerized water chemistry data acquisition and management system for nuclear plant secondary coolant systems. The Integrated Water Chemistry Monitoring System (IWCMS) provides on-line monitoring of conditions and rapid trend analysis of sampled data. So far it has been installed at GPU Three Mile Island unit 1 and at Toledo Edison Davis-Besse. The IWCMS meets the following utility needs for monitoring power plant chemistry: control of chemistry conditions to minimize corrosion and extend component/system life; continuous analysis of data from on-line detectors and grab samples; expediting of transient recovery actions with trend, alarm and evaluation capability; provision for rapid sharing of useful operational chemistry information; concentration of attention on evaluation instead of data manipulation. The system is composed of three functional parts: data acquisition hardware; PC-based computer system and customised system software. (author)

  17. Positronium chemistry

    CERN Document Server

    Green, James

    1964-01-01

    Positronium Chemistry focuses on the methodologies, reactions, processes, and transformations involved in positronium chemistry. The publication first offers information on positrons and positronium and experimental methods, including mesonic atoms, angular correlation measurements, annihilation spectra, and statistical errors in delayed coincidence measurements. The text then ponders on positrons in gases and solids. The manuscript takes a look at the theoretical chemistry of positronium and positronium chemistry in gases. Topics include quenching, annihilation spectrum, delayed coincidence

  18. Human Development VIII: A Theory of “Deep” Quantum Chemistry and Cell Consciousness: Quantum Chemistry Controls Genes and Biochemistry to Give Cells and Higher Organisms Consciousness and Complex Behavior

    Directory of Open Access Journals (Sweden)

    Søren Ventegodt

    2006-01-01

    Full Text Available Deep quantum chemistry is a theory of deeply structured quantum fields carrying the biological information of the cell, making it able to remember, intend, represent the inner and outer world for comparison, understand what it “sees”, and make choices on its structure, form, behavior and division. We suggest that deep quantum chemistry gives the cell consciousness and all the qualities and abilities related to consciousness. We use geometric symbolism, which is a pre-mathematical and philosophical approach to problems that cannot yet be handled mathematically. Using Occam’s razor we have started with the simplest model that works; we presume this to be a many-dimensional, spiral fractal. We suggest that all the electrons of the large biological molecules’ orbitals make one huge “cell-orbital”, which is structured according to the spiral fractal nature of quantum fields. Consciousness of single cells, multi cellular structures as e.g. organs, multi-cellular organisms and multi-individual colonies (like ants and human societies can thus be explained by deep quantum chemistry. When biochemical activity is strictly controlled by the quantum-mechanical super-orbital of the cell, this orbital can deliver energetic quanta as biological information, distributed through many fractal levels of the cell to guide form and behavior of an individual single or a multi-cellular organism. The top level of information is the consciousness of the cell or organism, which controls all the biochemical processes. By this speculative work inspired by Penrose and Hameroff we hope to inspire other researchers to formulate more strict and mathematically correct hypothesis on the complex and coherence nature of matter, life and consciousness.

  19. Analysis of multi-fragmentation reactions induced by relativistic heavy ions using the statistical multi-fragmentation model

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, T., E-mail: ogawa.tatsuhiko@jaea.go.jp [Research Group for Radiation Protection, Division of Environment and Radiation Sciences, Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency, Shirakata-Shirane, Tokai, Ibaraki 319-1195 (Japan); Sato, T.; Hashimoto, S. [Research Group for Radiation Protection, Division of Environment and Radiation Sciences, Nuclear Science and Engineering Directorate, Japan Atomic Energy Agency, Shirakata-Shirane, Tokai, Ibaraki 319-1195 (Japan); Niita, K. [Research Organization for Information Science and Technology, Shirakata-shirane, Tokai, Ibaraki 319-1188 (Japan)

    2013-09-21

    The fragmentation cross-sections of relativistic energy nucleus–nucleus collisions were analyzed using the statistical multi-fragmentation model (SMM) incorporated with the Monte-Carlo radiation transport simulation code particle and heavy ion transport code system (PHITS). Comparison with the literature data showed that PHITS-SMM reproduces fragmentation cross-sections of heavy nuclei at relativistic energies better than the original PHITS by up to two orders of magnitude. It was also found that SMM does not degrade the neutron production cross-sections in heavy ion collisions or the fragmentation cross-sections of light nuclei, for which SMM has not been benchmarked. Therefore, SMM is a robust model that can supplement conventional nucleus–nucleus reaction models, enabling more accurate prediction of fragmentation cross-sections.

  20. Analysis of multi-fragmentation reactions induced by relativistic heavy ions using the statistical multi-fragmentation model

    International Nuclear Information System (INIS)

    Ogawa, T.; Sato, T.; Hashimoto, S.; Niita, K.

    2013-01-01

    The fragmentation cross-sections of relativistic energy nucleus–nucleus collisions were analyzed using the statistical multi-fragmentation model (SMM) incorporated with the Monte-Carlo radiation transport simulation code particle and heavy ion transport code system (PHITS). Comparison with the literature data showed that PHITS-SMM reproduces fragmentation cross-sections of heavy nuclei at relativistic energies better than the original PHITS by up to two orders of magnitude. It was also found that SMM does not degrade the neutron production cross-sections in heavy ion collisions or the fragmentation cross-sections of light nuclei, for which SMM has not been benchmarked. Therefore, SMM is a robust model that can supplement conventional nucleus–nucleus reaction models, enabling more accurate prediction of fragmentation cross-sections

  1. Annual Report of Institute of Nuclear Chemistry and Technology 2001

    International Nuclear Information System (INIS)

    2002-06-01

    The INCT 2001 Annual Report is the review of scientific activities in all branches being developed in the Institute of Nuclear Chemistry and Technology in Warsaw. The studies are connected in general with the following fields: radiation chemistry and physics, radiation technologies, radiochemistry, stable isotopes, nuclear analytical methods, chemistry in general, radiobiology, process engineering, material engineering, structural studies and diagnostics, nucleonic control systems and accelerators and nuclear analytical methods

  2. Annual Report 2004 of Institute of Nuclear Chemistry and Technology

    International Nuclear Information System (INIS)

    Michalik, J.; Smulek, W.; Godlewska-Para, E.

    2005-06-01

    The INCT 2004 Annual Report is the review of scientific activities in all branches being developed in the Institute of Nuclear Chemistry and Technology Warsaw. The studies are connected in general with the following fields: radiation chemistry and physics, radiation technologies, radiochemistry, stable isotopes, nuclear analytical methods, chemistry in general, radiobiology, process engineering, material engineering, structural studies and diagnostics, nucleonic control systems and accelerators, radiobiology and nuclear analytical methods

  3. Annual Report 2004 of Institute of Nuclear Chemistry and Technology

    Energy Technology Data Exchange (ETDEWEB)

    Michalik, J; Smulek, W; Godlewska-Para, E [eds.

    2005-06-01

    The INCT 2004 Annual Report is the review of scientific activities in all branches being developed in the Institute of Nuclear Chemistry and Technology Warsaw. The studies are connected in general with the following fields: radiation chemistry and physics, radiation technologies, radiochemistry, stable isotopes, nuclear analytical methods, chemistry in general, radiobiology, process engineering, material engineering, structural studies and diagnostics, nucleonic control systems and accelerators, radiobiology and nuclear analytical methods.

  4. Annual Report of Institute of Nuclear Chemistry and Technology 2001

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-06-01

    The INCT 2001 Annual Report is the review of scientific activities in all branches being developed in the Institute of Nuclear Chemistry and Technology in Warsaw. The studies are connected in general with the following fields: radiation chemistry and physics, radiation technologies, radiochemistry, stable isotopes, nuclear analytical methods, chemistry in general, radiobiology, process engineering, material engineering, structural studies and diagnostics, nucleonic control systems and accelerators and nuclear analytical methods.

  5. Fragment-based quantitative structure-activity relationship (FB-QSAR) for fragment-based drug design.

    Science.gov (United States)

    Du, Qi-Shi; Huang, Ri-Bo; Wei, Yu-Tuo; Pang, Zong-Wen; Du, Li-Qin; Chou, Kuo-Chen

    2009-01-30

    In cooperation with the fragment-based design a new drug design method, the so-called "fragment-based quantitative structure-activity relationship" (FB-QSAR) is proposed. The essence of the new method is that the molecular framework in a family of drug candidates are divided into several fragments according to their substitutes being investigated. The bioactivities of molecules are correlated with the physicochemical properties of the molecular fragments through two sets of coefficients in the linear free energy equations. One coefficient set is for the physicochemical properties and the other for the weight factors of the molecular fragments. Meanwhile, an iterative double least square (IDLS) technique is developed to solve the two sets of coefficients in a training data set alternately and iteratively. The IDLS technique is a feedback procedure with machine learning ability. The standard Two-dimensional quantitative structure-activity relationship (2D-QSAR) is a special case, in the FB-QSAR, when the whole molecule is treated as one entity. The FB-QSAR approach can remarkably enhance the predictive power and provide more structural insights into rational drug design. As an example, the FB-QSAR is applied to build a predictive model of neuraminidase inhibitors for drug development against H5N1 influenza virus. (c) 2008 Wiley Periodicals, Inc.

  6. Non-thermally activated chemistry

    International Nuclear Information System (INIS)

    Stiller, W.

    1987-01-01

    The subject is covered under the following headings: state-of-the art of non-thermally activated chemical processes; basic phenomena in non-thermal chemistry including mechanochemistry, photochemistry, laser chemistry, electrochemistry, photo-electro chemistry, high-field chemistry, magneto chemistry, plasma chemistry, radiation chemistry, hot-atom chemistry, and positronium and muonium chemistry; elementary processes in non-thermal chemistry including nuclear chemistry, interactions of electromagnetic radiations, electrons and heavy particles with matter, ionic elementary processes, elementary processes with excited species, radicalic elementary processes, and energy-induced elementary processes on surfaces and interfaces; and comparative considerations. An appendix with historical data and a subject index is given. 44 figs., 41 tabs., and 544 refs

  7. Selective control of reformed composition of n-heptane via plasma chemistry

    KAUST Repository

    Manoj Kumar Reddy, P.

    2016-08-23

    This paper presents experimental results for reforming n-heptane in a temperature-controlled dielectric barrier discharge reactor to show detailed chemical composition in the products and to propose a potential method to control the product composition. Reformed products of n-heptane and water mixture in an inert Ar feed could be identified as hydrogen, carbon monoxide, oxygenates, and various hydrocarbons, having a wide range of carbon numbers. To selectively increase production of short-chain hydrocarbons, Ar was replaced by CH4. An increased pool of methyl radicals, via plasma chemistry of CH4, might facilitate to stabilize intermediate alkyls (R) into RCH3, which successfully increased short-chain hydrocarbon concentration. When CO2 was supplied instead of Ar (to provide enriched OH and O radicals), significantly higher oxygenate concentrations were obtained through the stabilization of alkyls as ROH (alcohol), and RC([Formula presented])R′ (ketone). The use of methane and carbon dioxide as feed to tailor the products of plasma-assisted reforming of n-heptane with methyl (CH3), or O radicals, is successfully demonstrated in the presence of water vapor. Detailed product analysis, such as product selection, rates and energy efficiency using a gas chromatograph and a gas chromatography mass spectrometer, will be elaborated upon. © 2016 Elsevier Ltd

  8. An Archeology of Fragments

    Directory of Open Access Journals (Sweden)

    Gerald L. Bruns

    2014-10-01

    Full Text Available This is a short (fragmentary history of fragmentary writing from the German Romantics (F. W. Schlegel, Friedrich Hölderlin to modern and contemporary concrete or visual poetry. Such writing is (often deliberately a critique of the logic of subsumption that tries to assimilate whatever is singular and irreducible into totalities of various categorical or systematic sorts. Arguably, the fragment (parataxis is the distinctive feature of literary Modernism, which is a rejection, not of what precedes it, but of what Max Weber called “the rationalization of the world” (or Modernity whose aim is to keep everything, including all that is written, under surveillance and control.

  9. Medicinal chemistry matters - a call for discipline in our discipline.

    Science.gov (United States)

    Johnstone, Craig

    2012-06-01

    Medicinal chemistry makes a vital contribution to small molecule drug discovery, and the quality of it contributes directly to research effectiveness as well as to downstream costs, speed and survival in development. In recent years, the discipline of medicinal chemistry has evolved and witnessed many noteworthy contributions that propose and offer potential improvements to medicinal chemistry practice; however, the impact of these ideas is limited by their acceptance and deployment into every-day activity and, as a result, the quality of medicinal chemistry remains variable. For the good of the industry and the medicinal chemistry discipline, there is a need to move from retrospective learning to prospective control of medicinal chemistry practice to improve cost effectiveness, probability of success and survival rates. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Reframing landscape fragmentation's effects on ecosystem services.

    Science.gov (United States)

    Mitchell, Matthew G E; Suarez-Castro, Andrés F; Martinez-Harms, Maria; Maron, Martine; McAlpine, Clive; Gaston, Kevin J; Johansen, Kasper; Rhodes, Jonathan R

    2015-04-01

    Landscape structure and fragmentation have important effects on ecosystem services, with a common assumption being that fragmentation reduces service provision. This is based on fragmentation's expected effects on ecosystem service supply, but ignores how fragmentation influences the flow of services to people. Here we develop a new conceptual framework that explicitly considers the links between landscape fragmentation, the supply of services, and the flow of services to people. We argue that fragmentation's effects on ecosystem service flow can be positive or negative, and use our framework to construct testable hypotheses about the effects of fragmentation on final ecosystem service provision. Empirical efforts to apply and test this framework are critical to improving landscape management for multiple ecosystem services. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Fragment Size Distribution of Blasted Rock Mass

    Science.gov (United States)

    Jug, Jasmin; Strelec, Stjepan; Gazdek, Mario; Kavur, Boris

    2017-12-01

    Rock mass is a heterogeneous material, and the heterogeneity of rock causes sizes distribution of fragmented rocks in blasting. Prediction of blasted rock mass fragmentation has a significant role in the overall economics of opencast mines. Blasting as primary fragmentation can significantly decrease the cost of loading, transport, crushing and milling operations. Blast fragmentation chiefly depends on the specific blast design (geometry of blast holes drilling, the quantity and class of explosive, the blasting form, the timing and partition, etc.) and on the properties of the rock mass (including the uniaxial compressive strength, the rock mass elastic Young modulus, the rock discontinuity characteristics and the rock density). Prediction and processing of blasting results researchers can accomplish by a variety of existing software’s and models, one of them is the Kuz-Ram model, which is possibly the most widely used approach to estimating fragmentation from blasting. This paper shows the estimation of fragmentation using the "SB" program, which was created by the authors. Mentioned program includes the Kuz-Ram model. Models of fragmentation are confirmed and calibrated by comparing the estimated fragmentation with actual post-blast fragmentation from image processing techniques. In this study, the Kuz-Ram fragmentation model has been used for an open-pit limestone quarry in Dalmatia, southern Croatia. The resulting calibrated value of the rock factor enables the quality prognosis of fragmentation in further blasting works, with changed drilling geometry and blast design parameters. It also facilitates simulation in the program to optimize blasting works and get the desired fragmentations of the blasted rock mass.

  12. Surface-Chemistry-Mediated Control of Individual Magnetic Helical Microswimmers in a Swarm.

    Science.gov (United States)

    Wang, Xiaopu; Hu, Chengzhi; Schurz, Lukas; De Marco, Carmela; Chen, Xiangzhong; Pané, Salvador; Nelson, Bradley J

    2018-05-31

    Magnetic helical microswimmers, also known as artificial bacterial flagella (ABFs), perform 3D navigation in various liquids under low-strength rotating magnetic fields by converting rotational motion to translational motion. ABFs have been widely studied as carriers for targeted delivery and release of drugs and cells. For in vivo/ in vitro therapeutic applications, control over individual groups of swimmers within a swarm is necessary for several biomedical applications such as drug delivery or small-scale surgery. In this work, we present the selective control of individual swimmers in a swarm of geometrically and magnetically identical ABFs by modifying their surface chemistry. We confirm experimentally and analytically that the forward/rotational velocity ratio of ABFs is independent of their surface coatings when the swimmers are operated below their step-out frequency (the frequency requiring the entire available magnetic torque to maintain synchronous rotation). We also show that ABFs with hydrophobic surfaces exhibit larger step-out frequencies and higher maximum forward velocities compared to their hydrophilic counterparts. Thus, selective control of a group of swimmers within a swarm of ABFs can be achieved by operating the selected ABFs at a frequency that is below their step-out frequencies but higher than the step-out frequencies of unselected ABFs. The feasibility of this method is investigated in water and in biologically relevant solutions. Selective control is also demonstrated inside a Y-shaped microfluidic channel. Our results present a systematic approach for realizing selective control within a swarm of magnetic helical microswimmers.

  13. Controls on Surface Water Chemistry in the Upper Merced River Basin, Yosemite National Park, California

    Science.gov (United States)

    Clow, David W.; Alisa Mast, M.; Campbell, Donald H.

    1996-05-01

    Surface water draining granitic bedrock in Yosemite National Park exhibits considerable variability in chemical composition, despite the relative homogeneity of bedrock chemistry. Other geological factors, including the jointing and distribution of glacial till, appear to exert strong controls on water composition. Chemical data from three surface water surveys in the upper Merced River basin conducted in August 1981, June 1988 and August 1991 were analysed and compared with mapped geological, hydrological and topographic features to identify the solute sources and processes that control water chemistry within the basin during baseflow. Water at most of the sampling sites was dilute, with alkalinities ranging from 26 to 77 equiv. l-1. Alkalinity was much higher in two subcatchments, however, ranging from 51 to 302 equiv. l-1. Base cations and silica were also significantly higher in these two catchments than in the rest of the watershed. Concentrations of weathering products in surface water were correlated to the fraction of each subcatchment underlain by surficial material, which is mostly glacial till. Silicate mineral weathering is the dominant control on concentrations of alkalinity, silica and base cations, and ratios of these constituents in surface water reflect the composition of local bedrock. Chloride concentrations in surface water samples varied widely, ranging from <1 to 96 equiv. l-1. The annual volume-weighted mean chloride concentration in the Merced River at the Happy Isles gauge from 1968 to 1990 was 26 equiv. l-1, which was five times higher than in atmospheric deposition (4-5 equiv. l-1), suggesting that a source of chloride exists within the watershed. Saline groundwater springs, whose locations are probably controlled by vertical jointing in the bedrock, are the most likely source of the chloride. Sulphate concentrations varied much less than most other solutes, ranging from 3 to 14 equiv. l-1. Concentrations of sulphate in quarterly samples

  14. Green chemistry: A tool in Pharmaceutical Chemistry

    OpenAIRE

    Smita Talaviya; Falguni Majumdar

    2012-01-01

    Green chemistry expresses an area of research developing from scientific discoveries about pollution awareness and it utilizes a set of principles that reduces or eliminates the use or generation of hazardous substances in all steps of particular synthesis or process. Chemists and medicinal scientists can greatly reduce the risk to human health and the environment by following all the valuable principles of green chemistry. The most simple and direct way to apply green chemistry in pharmaceut...

  15. Annual Report 2003 of the Institute of Nuclear Chemistry and Technology

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    The INCT 2003 Annual Report is the review of scientific activities in all branches being developed in the Institute of Nuclear Chemistry and Technology Warsaw. The studies are connected in general with the following fields: radiation chemistry and physics, radiation technologies, radiochemistry, stable isotopes, nuclear analytical methods, chemistry in general, radiobiology, process engineering, material engineering, structural studies, nucleonic control systems and accelerators.

  16. Annual Report 2003 of the Institute of Nuclear Chemistry and Technology

    International Nuclear Information System (INIS)

    2004-01-01

    The INCT 2003 Annual Report is the review of scientific activities in all branches being developed in the Institute of Nuclear Chemistry and Technology Warsaw. The studies are connected in general with the following fields: radiation chemistry and physics, radiation technologies, radiochemistry, stable isotopes, nuclear analytical methods, chemistry in general, radiobiology, process engineering, material engineering, structural studies, nucleonic control systems and accelerators

  17. Medium-scale melt-sodium fragmentation experiments

    International Nuclear Information System (INIS)

    Chu, T.Y.; Beattie, A.G.; Drotning, W.D.; Powers, D.A.

    1979-01-01

    The results of a series of fragmentation experiments involving up to 20 Kg of thermitically produced high temperature melts and 23 Kg of sodium are presented. Except for one experiment where some centimeter size particles are observed, the fragment distributions seem to be in the range of previous data. Spatial distribution of the fragments in the debris bed appears to be stratified. Scanning electron micrographs of fragments indicate fragmentation to be occurring in the molten state for the more intense interactions observed. Interaction data obtained show quiescent periods of 0.5 to 1.5 second between pressure pulses. The force impulse values per unit mass of melt seems to be in the same range as previous experiments

  18. Water chemistry and materials degradation in LWR'S

    International Nuclear Information System (INIS)

    Haenninen, H.; Toerroenen, K.; Aaltonen, P.

    1994-01-01

    Water chemistry plays a major role in corrosion, in erosion corrosion and in activity transport in NPPs; it impacts upon the operational safety of LWRs in two main ways: integrity of pressure boundary materials and activity transport and out-of-core radiation fields. A good control of water chemistry can significantly reduce these problems and improve plant safety, but economic pressures are leading to more rigorous operating conditions: fuel burnups are to be increased, higher efficiencies are to be achieved by running at higher temperatures and plant lifetimes are to be extended. Typical water chemistry specifications used in PWR and BWR plants are presented and the chemistry optimization is discussed. The complex interplay of metallurgical, mechanical and environmental factors in environmental sensitive cracking is shown, with details on studies for carbon steels, stainless steels and nickel base alloys. 20 refs., 8 figs., 4 tabs

  19. Assessing the lipophilicity of fragments and early hits

    Science.gov (United States)

    Mortenson, Paul N.; Murray, Christopher W.

    2011-07-01

    A key challenge in many drug discovery programs is to accurately assess the potential value of screening hits. This is particularly true in fragment-based drug design (FBDD), where the hits often bind relatively weakly, but are correspondingly small. Ligand efficiency (LE) considers both the potency and the size of the molecule, and enables us to estimate whether or not an initial hit is likely to be optimisable to a potent, druglike lead. While size is a key property that needs to be controlled in a small molecule drug, there are a number of additional properties that should also be considered. Lipophilicity is amongst the most important of these additional properties, and here we present a new efficiency index (LLEAT) that combines lipophilicity, size and potency. The index is intuitively defined, and has been designed to have the same target value and dynamic range as LE, making it easily interpretable by medicinal chemists. Monitoring both LE and LLEAT should help both in the selection of more promising fragment hits, and controlling molecular weight and lipophilicity during optimisation.

  20. An ideal teaching program of nuclear chemistry in the undergraduate chemistry curriculum

    International Nuclear Information System (INIS)

    Uenak, T.

    2009-01-01

    It is well known that several reports on the common educational problems of nuclear chemistry have been prepared by certain groups of experts from time to time. According to very important statements in these reports, nuclear chemistry and related courses generally do not take sufficient importance in undergraduate chemistry curricula and it was generally proposed that nuclear chemistry and related courses should be introduced into undergraduate chemistry curricula at universities worldwide. Starting from these statements, an ideal program in an undergraduate chemistry curriculum was proposed to be introduced into the undergraduate chemistry program at the Department of Chemistry, Ege University, in Izmir, Turkey during the regular updating of the chemistry curriculum. Thus, it has been believed that this Department of Chemistry has recently gained an ideal teaching program in the field of nuclear chemistry and its applications in scientific, industrial, and medical sectors. In this contribution, the details of this program will be discussed. (author)

  1. Discovery of Fragment-Derived Small Molecules for in Vivo Inhibition of Ketohexokinase (KHK)

    Energy Technology Data Exchange (ETDEWEB)

    Huard, Kim; Ahn, Kay; Amor, Paul; Beebe, David A.; Borzilleri, Kris A.; Chrunyk, Boris A.; Coffey, Steven B.; Cong, Yang; Conn, Edward L.; Culp, Jeffrey S.; Dowling, Matthew S.; Gorgoglione, Matthew F.; Gutierrez, Jemy A.; Knafels, John D.; Lachapelle, Erik A.; Pandit, Jayvardhan; Parris, Kevin D.; Perez, Sylvie; Pfefferkorn, Jeffrey A.; Price, David A.; Raymer, Brian; Ross, Trenton T.; Shavnya, Andre; Smith, Aaron C.; Subashi, Timothy A.; Tesz, Gregory J.; Thuma, Benjamin A.; Tu, Meihua; Weaver, John D.; Weng, Yan; Withka, Jane M.; Xing, Gang; Magee, Thomas V. (Pfizer)

    2017-05-23

    Increased fructose consumption and its subsequent metabolism have been implicated in hepatic steatosis, dyslipidemia, obesity, and insulin resistance in humans. Since ketohexokinase (KHK) is the principal enzyme responsible for fructose metabolism, identification of a selective KHK inhibitor may help to further elucidate the effect of KHK inhibition on these metabolic disorders. Until now, studies on KHK inhibition with small molecules have been limited due to the lack of viable in vivo pharmacological tools. Herein we report the discovery of 12, a selective KHK inhibitor with potency and properties suitable for evaluating KHK inhibition in rat models. Key structural features interacting with KHK were discovered through fragment-based screening and subsequent optimization using structure-based drug design, and parallel medicinal chemistry led to the identification of pyridine 12.

  2. Scientific basis for the choice of primary/secondary water chemistry

    International Nuclear Information System (INIS)

    Garnsey, R.

    1988-01-01

    The purpose of this paper is to illustrate the common scientific basis for the chemistry control strategies which have been developed. The evolution of chemistry control philosophies in some plant designs are outlined as examples. The essential requirement of water chemistry control is to preserve integrity of the circuit under all the environmental conditions experienced within that circuit. There may be specific additional requirements, as in the case of a PWR primary circuit, where boron concentration is used to control reactivity. The crucial requirement or concern can vary. In the primary circuit of a light water reactor the crucial requirement is to supress the activation and transportation of corrosion products and so minimize radiation fields around the circuit. On the secondary side of recirculating steam generators the critical requirement has been to preserve the integrity of generator tubing. In once-through steam generators the critical requirement may be the control of pressure losses associated with corrosion product deposits in the steam generator and the integrity of the turbine in addition to boiler integrity. (Nogami, K.)

  3. Chemistry for the nuclear energy of the future

    International Nuclear Information System (INIS)

    Chmielewski, A.G.

    2011-01-01

    Chemistry - radiochemistry, radiation chemistry and nuclear chemical engineering play a very important role in the nuclear power development. Even at present, the offered technology is well developed, but still several improvements are needed and proposed. These developments concern all stages of the technology; front end, reactor operation (coolant chemistry and installation components decontamination, noble gas release control), back end of fuel cycle, etc. Chemistry for a partitioning and a transmutation is a new challenge for the chemists and chemical engineers. The IV th generation of nuclear reactors cannot be developed without chemical solutions for fuel fabrication, radiation-coolants interaction phenomena understanding and spent fuel/waste treatment technologies elaboration. Radiochemical analytical methods are fundamental for radioecological monitoring of radioisotopes of natural and anthropological origin. This paper addresses just a few subjects and is not a detailed overview of the field, however it illustrates a role of chemistry for a safe and economical nuclear power development. (author)

  4. What are today's choices for PWRs water chemistry?

    International Nuclear Information System (INIS)

    Berge, P.

    1998-01-01

    Water chemistry has always been, from the very beginning of operation of power Pressurized Water Reactors (PWRs), an important factor in determining the integrity of many reactor components. For both the primary and secondary coolant circuits, the parameters to control the quality of the chemistry have been subject to changes in time. These changes were dictated mainly by corrosion problems which required an adjustment of the chemistry, before any modification could be made in the design or the selection of materials for the subsequently built reactors or replacement components. The situation today, despite 40 years of experience, still leaves open different options for the specifications of the chemistry of the circuits. These options are sometimes due to differences in design or materials of the circuits, but more often, to the perception by the plant chemists, of the role of the chemistry on the different phenomena which could affect the operation of their plant. Paul Cohen, who was well known in the nuclear industry for the early development of the chemistry in PWRs in the USA, used to say, 'if the head chemist has changed in a plant, the chemistry will change'. The purpose of this lecture is to discuss some of the options which are offered to the chemist in compliance with the basic principles of the chemistry guidelines. (J.P.N.)

  5. Fragmentation functions approach in pQCD fragmentation phenomena

    International Nuclear Information System (INIS)

    Rolli, S.

    1996-07-01

    Next-to-leading order parton fragmentation functions into light mesons are presented. They have been extracted from real and simulated e + e - data and used to predict inclusive single particle distributions at different machines

  6. Experience of Ko-Ri Unit 1 water chemistry

    International Nuclear Information System (INIS)

    Tae Il Lee

    1983-01-01

    The main focus is placed on operational experience in secondary system water chemistry (especially the steam generator) of the Ko-Ri nuclear power plant Unit 1, Republic of Korea, but primary side chemistry is also discussed. The major concern of secondary water chemistry in a PWR is that the condition of the steam generator be well maintained. Full flow deep bed condensate polishers have recently been installed and operation started in July 1982. Boric acid treatment of the steam generator was stopped and only the all volatile treatment method was used thereafter. A review of steam generator integrity, the chemistry control programme, secondary water quality, etc. is considered to be of great value regarding the operation of Unit 1 and future units now under startup testing or construction in the Republic of Korea. (author)

  7. Fragmentation of neck-like structures

    International Nuclear Information System (INIS)

    Montoya, C.; Bowman, D.R.; Peaslee, G.F.; Michigan State Univ., East Lansing, MI

    1994-01-01

    Evidence for intermediate mass fragment emission from neck-like structures joining projectile- and target-like residues has been observed for peripheral 129 Xe+ nat Cu collisions at E/A=50 MeV. These framents are emitted primarily at velocities intermediate between those of the projectile and the target. Relative to the charge distribution for fragments evaporated from the projectile-like residue, the distribution for ''neck'' emission shows an enhanced emission for fragments with 4 f < 8. (orig.)

  8. Forest Fragments Surrounded by Sugar Cane Are More Inhospitable to Terrestrial Amphibian Abundance Than Fragments Surrounded by Pasture

    Directory of Open Access Journals (Sweden)

    Paula Eveline Ribeiro D’Anunciação

    2013-01-01

    Full Text Available In recent years, there has been increasing interest in matrix-type influence on forest fragments. Terrestrial amphibians are good bioindicators for this kind of research because of low vagility and high philopatry. This study compared richness, abundance, and species composition of terrestrial amphibians through pitfall traps in two sets of semideciduous seasonal forest fragments in southeastern Brazil, according to the predominant surrounding matrix (sugar cane and pasture. There were no differences in richness, but fragments surrounded by sugar cane had the lowest abundance of amphibians, whereas fragments surrounded by pastures had greater abundance. The most abundant species, Rhinella ornata, showed no biometric differences between fragment groups but like many other amphibians sampled showed very low numbers of individuals in fragments dominated by sugar cane fields. Our data indicate that the sugar cane matrix negatively influences the community of amphibians present in fragments surrounded by this type of land use.

  9. Surface complement C3 fragments and cellular binding of microparticles in patients with SLE

    DEFF Research Database (Denmark)

    Winberg, Line Kjær; Nielsen, Claus Henrik; Jacobsen, Søren

    2017-01-01

    Objectives: To examine microparticles (MPs) from patients with SLE and healthy controls (HCs) by determining the cellular origin of the MPs, quantifying attached fragments of complement component 3 (C3) and assessing the ability of MPs to bind to circulating phagocytes and erythrocytes. These fea......Objectives: To examine microparticles (MPs) from patients with SLE and healthy controls (HCs) by determining the cellular origin of the MPs, quantifying attached fragments of complement component 3 (C3) and assessing the ability of MPs to bind to circulating phagocytes and erythrocytes...

  10. Chemistry-Nuclear Chemistry Division. Progress report, October 1980-September 1981

    International Nuclear Information System (INIS)

    Ryan, R.R.

    1982-05-01

    This report describes major progress in the research and development programs pursued by the Chemistry-Nuclear Chemistry Division of the Los Alamos National Laboratory during FY 1981. Topics covered include advanced analytical methods, atmospheric chemistry and transport, biochemistry, biomedical research, medical radioisotopes research, element migration and fixation, nuclear waste isolation research, inorganic and structural chemistry, isotope separation, analysis and applications, the newly established Nuclear Magnetic Resonance Center, atomic and molecular collisions, molecular spectroscopy, nuclear cosmochemistry, nuclear structure and reactions, pion charge exchange, radiochemical separations, theoretical chemistry, and unclassified weapons research

  11. Chemistry-Nuclear Chemistry Division. Progress report, October 1980-September 1981

    Energy Technology Data Exchange (ETDEWEB)

    Ryan, R.R. (comp.)

    1982-05-01

    This report describes major progress in the research and development programs pursued by the Chemistry-Nuclear Chemistry Division of the Los Alamos National Laboratory during FY 1981. Topics covered include advanced analytical methods, atmospheric chemistry and transport, biochemistry, biomedical research, medical radioisotopes research, element migration and fixation, nuclear waste isolation research, inorganic and structural chemistry, isotope separation, analysis and applications, the newly established Nuclear Magnetic Resonance Center, atomic and molecular collisions, molecular spectroscopy, nuclear cosmochemistry, nuclear structure and reactions, pion charge exchange, radiochemical separations, theoretical chemistry, and unclassified weapons research.

  12. Strategic elements of steam cycle chemistry control practices at TXU's Comanche Peak steam electric station

    International Nuclear Information System (INIS)

    Fellers, B.; Stevens, J.; Nichols, G.

    2002-01-01

    Early industry experience defined the critical importance of Chemistry Control Practices to maintaining long-term performance of PWR steam generators. These lessons provided the impetus for a number of innovations and alternate practices at Comanche Peak. For example, advanced amine investigations and implementation of results provided record low iron transport and deposition. The benefits of the surface-active properties of dimethyl-amine exceeded initial expectations. Operation of pre-coat polishers and steam generator blowdown demineralizers in the amine cycle enabled optimization of amine concentrations and stable pH control. The strategy for coordinated control of oxygen and hydrazine dosing complemented the advanced amine program for protective oxide stabilization. Additionally, a proactive chemical cleaning was performed on Unit 1 to prevent degradations from general fouling of steam generator tube-tube support plate (TSP) and top-of-tubesheet (TTS) crevices. This paper shares the results of these innovations and practices. Also, the bases, theory, and philosophy supporting the strategic elements of program will be presented. (authors)

  13. The control of stoichiometry in Epitaxial semiconductor structures. Interfacial Chemistry: Property relations. A workshop review

    Science.gov (United States)

    Bachmann, Klaus J.

    1995-01-01

    A workshop on the control of stoichiometry in epitaxial semiconductor structures was held on August 21-26, 1995 in the hotel Stutenhaus at Vesser in Germany. The secluded location of the workshop in the forest of Thuringia and its informal style stimulated extensive private discussions among the participants and promoted new contacts between young scientists from Eastern and Western Europe and the USA. Topics addressed by the presentations were interactions of precursors to heteroepitaxy and doping with the substrate surface, the control of interfacial properties under the conditions of heteroepitaxy for selected materials systems, methods of characterization of interfaces and native point defects in semiconductor heterostructures and an in depth evaluation of the present status of the control and characterization of the point defect chemistry for one specific semiconductor (ZnGeP2), including studies of both heterostructures and bulk single crystals. The selected examples of presentations and comments given here represent individual choices - made by the author to highlight major points of the discussions.

  14. Study of the fragmentation of astrophysical interest molecules (C{sub n}H{sub m}) induced by high velocity collision; Etude de la fragmentation de molecules d'interet astrophysique de type C{sub n}H{sub m} par collision atomique de haute vitesse

    Energy Technology Data Exchange (ETDEWEB)

    Tuna, Th

    2008-07-15

    This work shows the study of atom-molecule collision processes in the high velocity domain (v=4,5 a.u). The molecules concerned by this work are small unsaturated hydrocarbons C{sub 1-4}H and C{sub 3}H{sub 2}. Molecules are accelerated with the Tandem accelerator in Orsay and their fragmentation is analyzed by the 4{pi}, 100% efficient detector, AGAT. Thanks to a shape analysis of the current signal from the silicon detectors in association with the well known grid method, we are able to measure all the fragmentation channels of the incident molecule. These dissociation measurements have been introduced in the modelization of two objects of the interstellar medium in which a lot of hydrocarbon molecules have been observed (TMC1, horse-head nebula). We have extended our branching ratios obtained by high velocity collision to other electronic processes included in the chemical database like photodissociation and dissociative recombination. This procedure is feasible under an assumption of the statistical point of view of the molecular fragmentation. The deviations following our modification are very small in the modelization of TMC1 but significant in the photodissociation region. The first part is dedicated to the description of the experimental setting that has enabled us to study the fragmentation of C{sub n}H{sub m} molecules: the Orsay's Tandem accelerator and the Agat detector. The second part deals with negative ion sources and particularly with the Sahat source that is based on electronic impact and has shown good features for the production of anions and correct stability for its use with accelerators. The third part is dedicated to the experimental results in terms of cross-sections, number of fragments and branching ratios, associated to the various collisional processes. The last part presents an application of our measurement of fragmentation data to astro-chemistry. In this field, the simulation codes of the inter-stellar medium require databases

  15. Fragmentation of Ceramics in Rapid Expansion Mode

    Science.gov (United States)

    Maiti, Spandan; Geubelle, Philippe H.; Rangaswamy, Krishnan

    The study of the fragmentation process goes back to more than a century, motivated primarily by problems related to mining and ore handling (Grady and Kipp, 1985). Various theories have been proposed to predict the fragmentation stress and the fragment size and distribution. But the investigations are generally case specific and relate to only a narrow set of fragmentation processes. A number of theoretical studies of dynamic fragmentation in a rapidly expanding body can be found in the literature. For example, the study summarized in (Grady, 1982) presents a model based on a simple energy balance concept between the surface energy released due to fracture and the kinetic energy of the fragments. Subsequent refinements of the energy balance model have been proposed by (Glenn and Chudnovsky, 1986), which take into account the strain energy of the fragments and specify a threshold stress below which no fragmentation occurs. These models assume that the fracture events are instantaneous and occur simultaneously. Evidently, these assumptions are quite restrictive and these models can not take into account the transient nature of the fragmentation process after the onset of fracture in the material. A more recent model proposed by (Miller et al., 1999) however takes into account this time-dependent nature of the fragmentation event and the distribution of flaws of various strengths in the original material.

  16. Percolation versus microcanonical fragmentation - comparison of fragment size distribution: Where is the liquid-gas transition in nuclei?

    International Nuclear Information System (INIS)

    Jaqaman, H.R.; Birzeit Univ.; Papp, G.; Eoetvoes Lorand Tudomanyegyetem, Budapest; Gross, D.H.E.; Freie Univ. Berlin

    1990-01-01

    The distributions of fragments produced by microcanonical multifragmentation of hot nuclei are compared with the cluster distributions predicted by a bond percolation model on a finite lattice. The conditional moments of these distributions are used together with the correlations between the largest three fragments in each event. Whereas percolation and statistical nuclear fragmentation agree in many details as in the usual plots of the averaged moments of the fragment distributions which yield the critical exponents, they turn out to be essentially different when less averaged quantities or correlations are considered. The differences between the predictions of the two models are mainly due to the particularities of the nuclear problem, especially the effect of the long-range Coulomb force which favours the break-up of the highly excited nucleus into two large fragments (pseudo-fission) and, to a somewhat lesser extent, enhances the possibility for the cracking of the nucleus into more than two large fragments. The fission events are, however, clearly separated from a second branch of critical correlations which shows up clearly in both nuclear fragmentation and percolation. We think that this critical correlation branch is due to the liquid-gas phase transition in finite nuclei. (orig.)

  17. The formation of planets by disc fragmentation

    Directory of Open Access Journals (Sweden)

    Stamatellos Dimitris

    2013-04-01

    Full Text Available I discuss the role that disc fragmentation plays in the formation of gas giant and terrestrial planets, and how this relates to the formation of brown dwarfs and low-mass stars, and ultimately to the process of star formation. Protostellar discs may fragment, if they are massive enough and can cool fast enough, but most of the objects that form by fragmentation are brown dwarfs. It may be possible that planets also form, if the mass growth of a proto-fragment is stopped (e.g. if this fragment is ejected from the disc, or suppressed and even reversed (e.g by tidal stripping. I will discuss if it is possible to distinguish whether a planet has formed by disc fragmentation or core accretion, and mention of a few examples of observed exoplanets that are suggestive of formation by disc fragmentation.

  18. Extraction of 16th Century Calender Fragments

    DEFF Research Database (Denmark)

    Holck, Jakob Povl; Etheridge, Christian

    at the Cultural Heritage & Archaeometric Research Team, SDU. Upon finding medieval manuscript fragments in the university library’s special collections, scholars at the Centre for Medieval Literature are consulted. In most cases, digital pictures of the finds will circulate in the international community...... fragments may require extensive use of Big Data and other forms of analysis in order to be identified. Usually, the university library prefers not to remove the fragments from their “fragment carriers”. In order to read fragments that are only partially visible or invisible, x-ray technology may be deployed...... of medieval scholars. Thousands of 16th and 17th Century books are stored in the University Library of Southern Denmark. One out of five of these books is expected to contain medieval manuscript fragments or fragments of rare prints, e.g. incunabula....

  19. Fundamentals of nuclear chemistry

    International Nuclear Information System (INIS)

    Majer, V.

    1982-01-01

    The author of the book has had 25 years of experience at the Nuclear Chemistry of Prague Technical University. In consequence, the book is intended as a basic textbook for students of this field. Its main objectives are an easily understandable presentation of the complex subject and in spite of the uncertainty which still characterizes the definition and subjects of nuclear chemistry - a systematic classification and logical structure. Contents: 1. Introduction (history and definition); 2. General nuclear chemistry (physical fundamentals, hot atom chemistry, interaction of nuclear radiation with matter, radioactive elements, isotope effects, isotope exchange, chemistry of radioactive trace elements); 3. Methods of nuclear chemistry of nuclear chemistry (radiochemical methods, activation, separation and enrichment chemistry); 4. Preparative nuclear chemistry (isotope production, labelled compounds); 5. Analytival nuclear chemistry; 6. Applied nuclear chemistry (isotope applications in general physical and analytical chemistry). The book is supplemented by an annex with tables, a name catalogue and a subject index which will facilitate access to important information. (RB) [de

  20. Investigating Affective Experiences in the Undergraduate Chemistry Laboratory: Students' Perceptions of Control and Responsibility

    Science.gov (United States)

    Galloway, Kelli R.; Malakpa, Zoebedeh; Bretz, Stacey Lowery

    2016-01-01

    Meaningful learning requires the integration of cognitive and affective learning with the psychomotor, i.e., hands-on learning. The undergraduate chemistry laboratory is an ideal place for meaningful learning to occur. However, accurately characterizing students' affective experiences in the chemistry laboratory can be a very difficult task. While…

  1. Annual Report of the Institute of Nuclear Chemistry and Technology 2000

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-06-01

    The INCT 2000 Annual Report is the review of scientific activities in all branches being developed in the Institute of Nuclear Chemistry and Technology Warsaw. The studies are connected in general with the following fields: radiation chemistry and physics, radiation technologies, radiochemistry, stable isotopes, nuclear analytical methods, chemistry in general, radiobiology, process engineering, material engineering, structural studies and diagnostics and nucleonic control systems and accelerators.

  2. Annual Report of the Institute of Nuclear Chemistry and Technology 2000

    International Nuclear Information System (INIS)

    2001-06-01

    The INCT 2000 Annual Report is the review of scientific activities in all branches being developed in the Institute of Nuclear Chemistry and Technology Warsaw. The studies are connected in general with the following fields: radiation chemistry and physics, radiation technologies, radiochemistry, stable isotopes, nuclear analytical methods, chemistry in general, radiobiology, process engineering, material engineering, structural studies and diagnostics and nucleonic control systems and accelerators

  3. Scientific Information Analysis of Chemistry Dissertations Using Thesaurus of Chemistry

    Directory of Open Access Journals (Sweden)

    Taghi Rajabi

    2017-09-01

    Full Text Available : Concept maps of chemistry can be obtained from thesaurus of chemistry. Analysis of information in the field of chemistry is done at graduate level, based on comparing and analyzing chemistry dissertations by using these maps. Therefore, the use of thesaurus for analyzing scientific information is recommended. Major advantage of using this method, is that it is possible to obtain a detailed map of all academic researches across all branches of science. The researches analysis results in chemical science can play a key role in developing strategic research policies, educational programming, linking universities to industries and postgraduate educational programming. This paper will first introduce the concept maps of chemistry. Then, emerging patterns from the concept maps of chemistry will be used to analyze the trend in the academic dissertations in chemistry, using the data collected and stored in our database at Iranian Research Institute for Information Science and Technology (IranDoc over the past 10 years (1998-2009.

  4. Construction of a 3D-shaped, natural product like fragment library by fragmentation and diversification of natural products.

    Science.gov (United States)

    Prescher, Horst; Koch, Guido; Schuhmann, Tim; Ertl, Peter; Bussenault, Alex; Glick, Meir; Dix, Ina; Petersen, Frank; Lizos, Dimitrios E

    2017-02-01

    A fragment library consisting of 3D-shaped, natural product-like fragments was assembled. Library construction was mainly performed by natural product degradation and natural product diversification reactions and was complemented by the identification of 3D-shaped, natural product like fragments available from commercial sources. In addition, during the course of these studies, novel rearrangements were discovered for Massarigenin C and Cytochalasin E. The obtained fragment library has an excellent 3D-shape and natural product likeness, covering a novel, unexplored and underrepresented chemical space in fragment based drug discovery (FBDD). Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Amplifier channel for a fission fragment semiconductor detector

    International Nuclear Information System (INIS)

    Tyurin, G.P.

    1981-01-01

    To compensate the decrease of the transformation coefficient of fission fragment semiconductor detector (SCD) developed is a special amplification channel with controlled transfer coefficient. The block diagram of the channel is presented, the main functional units of which are as follows: preamplifying head with charge-sensitive and timing preamplifiers, linear amplifier and the circuit of spectrum position stabilization, which includes a differential discriminator, integrator and reference signal generator. The amplification channel is made in the CAMAC standard and has the following specifications: dinamical input capacitance of charge-sensitive amplifier c=10000 n PHI, signal amplitude at output of the linear amplifier at energy of fission fragments of 120 MeV has negative polarity and is equal to 5 V. Pulse amplitude change at SCD sensitivity decrease to 50% constitutes not more than 1%. Timing preamplifier has the gain factor at voltage of K=80 at front duration of 3.5 nc. Time resolution of the amplification channel is not worse than 1 nc. Dimensions of preamplifying head are 40x40x15 mm. The amplification channel permitted to use SCD for long-term measurements of fission fragment spectra [ru

  6. Fluctuations in the fragmentation process

    International Nuclear Information System (INIS)

    Botet, R.; Ploszajczak, M.

    1993-01-01

    Some general framework of sequential fragmentation is presented, as provided by the newly proposed Fragmentation - Inactivation - Binary model, and to study briefly its basic and universal features. This model includes as particular cases most of the previous kinetic fragmentation models. In particular it is discussed how one arrives in this framework to the critical behaviour, called the shattering transition. This model is then compared to recent data on gold multifragmentation at 600 MeV/nucl. (authors) 20 refs., 5 figs

  7. The spectroscopy of fission fragments

    International Nuclear Information System (INIS)

    Phillips, W.R.

    1998-01-01

    High-resolution measurements on γ rays from fission fragments have provided a rich source of information, unobtainable at the moment in any other way, on the spectroscopy of neutron-rich nuclei. In recent years important data have been obtained on the yrast- and near yrast-structure of neutron-rich fission fragments. We discuss the scope of measurements which can be made on prompt gamma rays from secondary fission fragments, the techniques used in the experiments and some results recently obtained. (author)

  8. Velocity distribution of fragments of catastrophic impacts

    Science.gov (United States)

    Takagi, Yasuhiko; Kato, Manabu; Mizutani, Hitoshi

    1992-01-01

    Three dimensional velocities of fragments produced by laboratory impact experiments were measured for basalts and pyrophyllites. The velocity distribution of fragments obtained shows that the velocity range of the major fragments is rather narrow, at most within a factor of 3 and that no clear dependence of velocity on the fragment mass is observed. The NonDimensional Impact Stress (NDIS) defined by Mizutani et al. (1990) is found to be an appropriate scaling parameter to describe the overall fragment velocity as well as the antipodal velocity.

  9. Fragmentation in DNA double-strand breaks

    International Nuclear Information System (INIS)

    Wei Zhiyong; Suzhou Univ., Suzhou; Zhang Lihui; Li Ming; Fan Wo; Xu Yujie

    2005-01-01

    DNA double strand breaks are important lesions induced by irradiations. Random breakage model or quantification supported by this concept is suitable to analyze DNA double strand break data induced by low LET radiation, but deviation from random breakage model is more evident in high LET radiation data analysis. In this work we develop a new method, statistical fragmentation model, to analyze the fragmentation process of DNA double strand breaks. After charged particles enter the biological cell, they produce ionizations along their tracks, and transfer their energies to the cells and break the cellular DNA strands into fragments. The probable distribution of the fragments is obtained under the condition in which the entropy is maximum. Under the approximation E≅E 0 + E 1 l + E 2 l 2 , the distribution functions are obtained as exp(αl + βl 2 ). There are two components, the one proportional to exp(βl 2 ), mainly contributes to the low mass fragment yields, the other component, proportional to exp(αl), decreases slowly as the mass of the fragments increases. Numerical solution of the constraint equations provides parameters α and β. Experimental data, especially when the energy deposition is higher, support the statistical fragmentation model. (authors)

  10. The role of water chemistry and geomorphic control in the presence of Didymosphenia geminata in Quebec

    Science.gov (United States)

    Gillis, C.; Gabor, R. S.; Cullis, J. D.; Ran, L.; Hassan, M. A.

    2010-12-01

    waters which offer high solar radiation as well as stable riverbed. Both water chemistry and geomorphic factors appear to control Didymosphenia geminata spatial patterns and occurrence.

  11. Diverse applications of radiation chemistry

    International Nuclear Information System (INIS)

    Cooper, R.

    1998-01-01

    Radiation chemistry began as early radiotherapists needed a reliable and appropriate dosimeter. The iron sulphate dosimeter, using ferrous iron in sulphuric acid and oxidation by irradiation, was a nasty brew of chemicals but it was sensitive, reliable and conveniently had the same density as human tissue. Water irradiation chemistry studies were driven by the need to understand the fundamental processes in radiotherapy; to control the corrosion problems in the cooling/ heat exchange systems of nuclear reactors and to find stable solvents and reagents for use in spent fuel element processing. The electrical and mechanical stability of materials in high radiation fields stimulated the attention of radiation chemists to the study of defects in solids. The coupled use of radiation and Electron Spin Resonance (ESR) enabled the identity of defect structures to be probed. This research led to the development of the sensitive Thermoluminescent Dosimeters, TLD's and a technique for dating of archaeological pottery artefacts. Radiation chemistry in the area of medicine is very active with fundamental studies of the mechanism of DNA strand breakage and the development of radiation sensitisers and protectors for therapeutic purposes. The major area of polymer radiation chemistry is one which Australia commands great international respect

  12. Fission fragment yields from heavy-ion-induced reactions measured with a fragment separator

    Science.gov (United States)

    Tarasov, O. B.; Delaune, O.; Farget, F.; Morrissey, D. J.; Amthor, A. M.; Bastin, B.; Bazin, D.; Blank, B.; Cacéres, L.; Chbihi, A.; Fernández-Dominguez, B.; Grévy, S.; Kamalou, O.; Lukyanov, S. M.; Mittig, W.; Pereira, J.; Perrot, L.; Saint-Laurent, M.-G.; Savajols, H.; Sherrill, B. M.; Stodel, C.; Thomas, J. C.; Villari, A. C.

    2018-04-01

    The systematic study of fission fragment yields under different initial conditions has provided valuable experimental data for benchmarking models of fission product yields. Nuclear reactions using inverse kinematics coupled to the use of a high-resolution spectrometer with good fragment identification are shown here to be a powerful tool to measure the inclusive isotopic yields of fission fragments. In-flight fusion-fission was used in this work to produce secondary beams of neutron-rich isotopes in the collisions of a 238U beam at 24 MeV/u with 9Be and 12C targets at GANIL using the LISE3 fragment separator. Unique identification of the A, Z, and atomic charge state, q, of fission products was attained with the Δ E- TKE-B ρ- ToF measurement technique. Mass, and atomic number distributions are reported for the two reactions. The results show the importance of different reaction mechanisms in the two cases. The optimal target material for higher yields of neutron-rich high- Z isotopes produced in fusion-fission reactions as a function of projectile energy is discussed.

  13. Political fragmentation and widening disparities in African-American and white mortality, 1972-1988.

    Science.gov (United States)

    Kim, Yonsu; Bruckner, Tim A

    2016-12-01

    During the 1970s and 1980s in the U.S., population movement, urban sprawl and urban governance reform led to a proliferation of local, autonomous jurisdictions. Prior literature examines how this creation of local governments, also referred to as political fragmentation, contributes to economic growth and social inequality. We examine the impact of political fragmentation on health equity by testing the hypothesis that the mortality disparity between whites and African-Americans varies positively with political fragmentation. We retrieved mortality data from the multiple cause-of-death file and calculated total number of local governments per 1000 residents in a county to measure the degree of political fragmentation. We focused on 226 U.S. counties with population size greater than 200,000 and restricted the analysis to four distinct periods with overlapping government and mortality data (1972-73, 1977-78, 1982-83, and 1987-88). We applied generalized estimating equation methods that permit analysis of clustered data over time. Methods also controlled for the age structure of the population, reductions in mortality over time, and confounding by county-level sociodemographic variables. Adjusted coefficients of fragmentation are positive and statistically significant for both whites (coef: 2.60, SE: 0.60, p politically fragmented urban counties and/or time periods. From 1972 to 1988, political fragmentation in large urban counties moves positively with the racial/ethnic gap in mortality between whites and African-Americans. We discuss intervening mechanisms through which political fragmentation may disproportionately affect mortality among African-Americans.

  14. Current fragmentation in deep inelastic scattering

    International Nuclear Information System (INIS)

    Hamer, C.J.

    1975-04-01

    It is argued that the current fragmentation products in deep inelastic electron scattering will not be distributed in a 'one-dimensional' rapidity plateau as in the parton model picture of Feynman and Bjorken. A reaction mechanism with a multiperipheral topology, but which the above configuration might have been achieved, does not in fact populate the current fragmentation plateau; and unless partons are actually observed in the final state, it cannot lead to Bjorken scaling. The basic reason for this failure is shown to be the fact that when a particle is produced in the current fragmentation plateau, the adjacent momentum transfer in the multiperipheral chain becomes large and negative: such processes are inevitably suppressed. Instead, the current fragmentation products are likely to be generated by a fragmentation, or sequential decay process. (author)

  15. WWER water chemistry related to fuel cladding behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Kysela, J; Zmitko, M [Nuclear Research Inst. plc., Rez (Czech Republic); Vrtilkova, V [Nuclear Fuel Inst., Prague (Czech Republic)

    1997-02-01

    Operational experience in WWER primary water chemistry and corrosion related to the fuel cladding is reviewed. Insignificant corrosion of fuel cladding was found which is caused by good corrosion resistance of Zr1Nb material and relatively low coolant temperature at WWER-440 reactor units. The differences in water chemistry control is outlined and an attention to the question of compatibility of Zircaloys with WWER water chemistry is given. Some results of research and development in field of zirconium alloy corrosion behaviour are discussed. Experimental facility for in-pile and out-of-pile cladding material corrosion testing is shown. (author). 14 refs, 5 figs, 3 tabs.

  16. Fragment emission from modestly excited nuclear systems

    Energy Technology Data Exchange (ETDEWEB)

    Lou, Y. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Souza, R.T. de [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Chen, S.L. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Cornell, E.W. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Davin, B. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Fox, D. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Hamilton, T.M. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Mcdonald, K. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility; Tsang, M.B. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Glasmacher, T. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Dinius, J. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Gelbke, C.K. [Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Handzy, D.O. [Indiana Univ., Bloomington, IN (United States). Dept. of Chemistry]|[Indiana Univ., Bloomington, IN (United States). Cyclotron Facility]|[Michigan State Univ., East Lansing, MI (United States). National Superconducting Cyclotron Lab.; Hsi, W.C.

    1996-07-08

    Fragment emission patterns occurring in nuclear systems of modest excitation are studied. Exclusive measurement of fragment emission in {sup 14}N+{sup 197}Au reactions at E/A=100, 130 and 156 MeV allows selection of central collisions where a single source dominates the decay. Low threshold measurement of IMF emission for these events allows investigation of the influence of detector threshold effects. The time scale of fragment emission is deduced using fragment-fragment velocity correlations. Comparisons are made to the predictions of a statistical decay model. (orig.).

  17. The spectroscopy of fission fragments

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, W.R. [Department of Physics and Astronomy, University of Manchester, Manchester, M13 9PL (United Kingdom); Collaboration: La Direction des Sciences de la Matiere du CEA (FR); Le Fonds National de la Recherche Scientifique de Belgique (BE)

    1998-12-31

    High-resolution measurements on {gamma} rays from fission fragments have provided a rich source of information, unobtainable at the moment in any other way, on the spectroscopy of neutron-rich nuclei. In recent years important data have been obtained on the yrast- and near yrast-structure of neutron-rich fission fragments. We discuss the scope of measurements which can be made on prompt gamma rays from secondary fission fragments, the techniques used in the experiments and some results recently obtained. (author) 24 refs., 8 figs., 1 tab.

  18. Endovascular Removal of Fractured Inferior Vena Cava Filter Fragments: 5-Year Registry Data with Prospective Outcomes on Retained Fragments.

    Science.gov (United States)

    Kesselman, Andrew J; Hoang, Nam Sao; Sheu, Alexander Y; Kuo, William T

    2018-06-01

    To evaluate the safety and efficacy of attempted percutaneous filter fragment removal during retrieval of fractured inferior vena cava (IVC) filters and to report outcomes associated with retained filter fragments. Over a 5-year period, 82 consecutive patients presenting with a fractured IVC filter were prospectively enrolled into an institutional review board-approved registry. There were 27 men and 55 women (mean, 47 y; range, 19-85 y). After main filter removal, percutaneous removal of fragments was attempted if they were deemed intravascular and accessible on preprocedural computed tomography (CT), cone-beam CT, and/or intravascular ultrasound; distal pulmonary artery (PA) fragments were left alone. A total of 185 fragments were identified (81 IVC, 33 PA, 16 cardiac, 2 hepatic vein, 1 renal vein, 1 aorta, 51 retroperitoneal). Mean filter dwell time was 2,183 days (range, 59-9,936 d). Eighty-seven of 185 fragments (47%) were deemed amenable to attempted removal: 65 IVC, 11 PA, 8 cardiac, 2 hepatic, and 1 aortic. Primary safety outcomes were major procedure-related complications. Fragment removal was successful in 78 of 87 cases (89.7%; 95% confidence interval [CI], 81.3-95.2). There were 6 minor complications with no consequence (6.9%; 95% CI, 2.6-14.4) involving intraprocedural fragment embolization and 1 major complication (1.1%; 95% CI, 0.0-6.2), a cardiac tamponade that was successfully treated. The complication rate from attempted cardiac fragment removal was 12.5% (1 of 8; 95% CI, 0.3-52.7). Among patients with retained cardiopulmonary fragments (n = 19), 81% remained asymptomatic during long-term clinical follow-up of 845 days (range, 386-2,071 d). Percutaneous removal of filter fragments from the IVC and proximal PAs is safe and effective overall, but attempted intracardiac fragment removal carries a higher risk of complication. Most residual filter fragments not amenable to percutaneous removal remain asymptomatic and may be monitored clinically

  19. Exploration of fluorine chemistry at the multidisciplinary interface of chemistry and biology.

    Science.gov (United States)

    Ojima, Iwao

    2013-07-05

    Over the last three decades, my engagement in "fluorine chemistry" has evolved substantially because of the multidisciplinary nature of the research programs. I began my research career as a synthetic chemist in organometallic chemistry and homogeneous catalysis directed toward organic synthesis. Then, I was brought into a very unique world of "fluorine chemistry" in the end of 1970s. I started exploring the interface of fluorine chemistry and transition metal homogeneous catalysis first, which was followed by amino acids, peptides, and peptidomimetics for medicinal chemistry. Since then, I have been exploring the interfaces of fluorine chemistry and multidisciplinary fields of research involving medicinal chemistry, chemical biology, cancer biology, and molecular imaging. This perspective intends to cover my fruitful endeavor in the exploration of fluorine chemistry at the multidisciplinary interface of chemistry and biology in a chronological order to show the evolution of my research interest and strategy.

  20. Modeling local chemistry in PWR steam generator crevices

    International Nuclear Information System (INIS)

    Millett, P.J.

    1997-01-01

    Over the past two decades steam generator corrosion damage has been a major cost impact to PWR owners. Crevices and occluded regions create thermal-hydraulic conditions where aggressive impurities can become highly concentrated, promoting localized corrosion of the tubing and support structure materials. The type of corrosion varies depending on the local conditions, with stress corrosion cracking being the phenomenon of most current concern. A major goal of the EPRI research in this area has been to develop models of the concentration process and resulting crevice chemistry conditions. These models may then be used to predict crevice chemistry based on knowledge of bulk chemistry, thereby allowing the operator to control corrosion damage. Rigorous deterministic models have not yet been developed; however, empirical approaches have shown promise and are reflected in current versions of the industry-developed secondary water chemistry guidelines

  1. DIAGNOSTIC CHARACTERISTICS OF THE COMPUTER TESTS FORMED BY METHOD OF RESTORED FRAGMENTS

    Directory of Open Access Journals (Sweden)

    Oleksandr O. Petkov

    2013-03-01

    Full Text Available Definition of validity and reliability of tests which are formed by a method of restored fragments is considered in the article. The structure of the controlled theoretical material of limit field of knowledge, language expressions that describe the subject of control, and reliability of test, is analyzed. The technique of definition of the most important components of reliability of the considered tests is given: reliability of quantitative determination of coefficient of assimilation and technological reliability. Results of the lead pedagogical experiments have proved, that tests of the given class allow to make the control of mastering of a theoretical material over a level of reproduction in any field of knowledge with high reliability. It is shown, that validity tests with restored fragments basically caused by a degree of structurization and methodical study of a controllable material and can achieve beforehand set parameters, down to a level of absolute validity.

  2. Nuclear chemistry

    International Nuclear Information System (INIS)

    Vertes, A.; Kiss, I.

    1987-01-01

    This book is an introduction to the application of nuclear science in modern chemistry. The first group of chapters discuss the basic phenomena and concepts of nuclear physics with emphasis on their relation to chemical problems, including the main properties and the composition of atomic nuclei, nuclear reactions, radioactive decay and interactions of radiation with matter. These chapters provide the basis for understanding the following chapters which encompass the wide scope of nuclear chemistry. The methods of the investigation of chemical structure based on the interaction of nuclear radiation with matter including positronium chemistry and other exotic atoms is elaborated in particular detail. Separate chapters are devoted to the use of radioactive tracers, the chemical consequences of nuclear processes (i.e. hot atom chemistry), radiation chemistry, isotope effects and their applications, and the operation of nuclear reactors

  3. Nuclear chemistry

    International Nuclear Information System (INIS)

    Vertes, A.; Kiss, I.

    1987-01-01

    This book is an introduction to the application of nuclear science in modern chemistry. The first group of chapters discuss the basic phenomena and concepts of nuclear physics with emphasis on their relation to chemical problems, including the main properties and the composition of atomic nuclei, nuclear reactions, radioactive decay and interactions of radiation with matter. These chapters provide the basis for understanding the following chapters which encompass the wide scope of nuclear chemistry. The methods of the investigation of chemical structure based on the interaction of nuclear radiation with matter including positronium chemistry and other exotic atoms is elaborated in particular detail. Separate chapters are devoted to the use of radioactive tracers, the chemical consequences of nuclear processes (i.e. hot atom chemistry), radiation chemistry, isotope effects and their applications, and the operation of nuclear reactors. (Auth.)

  4. Direct access to dithiobenzoate RAFT agent fragmentation rate coefficients by ESR spin-trapping.

    Science.gov (United States)

    Ranieri, Kayte; Delaittre, Guillaume; Barner-Kowollik, Christopher; Junkers, Thomas

    2014-12-01

    The β-scission rate coefficient of tert-butyl radicals fragmenting off the intermediate resulting from their addition to tert-butyl dithiobenzoate-a reversible addition-fragmentation chain transfer (RAFT) agent-is estimated via the recently introduced electron spin resonance (ESR)-trapping methodology as a function of temperature. The newly introduced ESR-trapping methodology is critically evaluated and found to be reliable. At 20 °C, a fragmentation rate coefficient of close to 0.042 s(-1) is observed, whereas the activation parameters for the fragmentation reaction-determined for the first time-read EA = 82 ± 13.3 kJ mol(-1) and A = (1.4 ± 0.25) × 10(13) s(-1) . The ESR spin-trapping methodology thus efficiently probes the stability of the RAFT adduct radical under conditions relevant for the pre-equilibrium of the RAFT process. It particularly indicates that stable RAFT adduct radicals are indeed formed in early stages of the RAFT poly-merization, at least when dithiobenzoates are employed as controlling agents as stipulated by the so-called slow fragmentation theory. By design of the methodology, the obtained fragmentation rate coefficients represent an upper limit. The ESR spin-trapping methodology is thus seen as a suitable tool for evaluating the fragmentation rate coefficients of a wide range of RAFT adduct radicals. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Fragger: a protein fragment picker for structural queries.

    Science.gov (United States)

    Berenger, Francois; Simoncini, David; Voet, Arnout; Shrestha, Rojan; Zhang, Kam Y J

    2017-01-01

    Protein modeling and design activities often require querying the Protein Data Bank (PDB) with a structural fragment, possibly containing gaps. For some applications, it is preferable to work on a specific subset of the PDB or with unpublished structures. These requirements, along with specific user needs, motivated the creation of a new software to manage and query 3D protein fragments. Fragger is a protein fragment picker that allows protein fragment databases to be created and queried. All fragment lengths are supported and any set of PDB files can be used to create a database. Fragger can efficiently search a fragment database with a query fragment and a distance threshold. Matching fragments are ranked by distance to the query. The query fragment can have structural gaps and the allowed amino acid sequences matching a query can be constrained via a regular expression of one-letter amino acid codes. Fragger also incorporates a tool to compute the backbone RMSD of one versus many fragments in high throughput. Fragger should be useful for protein design, loop grafting and related structural bioinformatics tasks.

  6. Kaon fragmentation function from NJL-jet model

    International Nuclear Information System (INIS)

    Matevosyan, Hrayr H.; Thomas, Anthony W.; Bentz, Wolfgang

    2010-01-01

    The NJL-jet model provides a sound framework for calculating the fragmentation functions in an effective chiral quark theory, where the momentum and isospin sum rules are satisfied without the introduction of ad hoc parameters [1]. Earlier studies of the pion fragmentation functions using the Nambu-Jona-Lasinio (NJL) model within this framework showed good qualitative agreement with the empirical parameterizations. Here we extend the NJL-jet model by including the strange quark. The corrections to the pion fragmentation function and corresponding kaon fragmentation functions are calculated using the elementary quark to quark-meson fragmentation functions from NJL. The results for the kaon fragmentation function exhibit a qualitative agreement with the empirical parameterizations, while the unfavored strange quark fragmentation to pions is shown to be of the same order of magnitude as the unfavored light quark's. The results of these studies are expected to provide important guidance for the analysis of a large variety of semi-inclusive data.

  7. VGB primary and secondary side water chemistry guidelines for PWR plants

    International Nuclear Information System (INIS)

    Neder, H.; Wolter, D.; Staudt, U.

    2007-01-01

    The recent revision of the VGB Water Chemistry Guidelines was issued in 2005 and published in the second half of 2006. These guidelines are based on the primary and secondary side operating chemistry experience with all Siemens designed pressurized water reactors gained since the beginning of the 1980s. These guidelines cover For the primary side chemistry Modified lithium boron chemistry, Zinc chemistry for dose rate reduction, Enriched boric acid (EBA) chemistry for high duty core design For the secondary side chemistry High all-volatile treatment (AVT) chemistry (high pH operation) Oxygen injection in the secondary side Especially for the secondary side chemistry, compared with the water chemistry guidelines of other organizations worldwide, these Guidelines are less stringent, providing more operational flexibility to the plant operation, and can be applied for all new designs of steam generators with egg-crates or broached hole tube supports and with I 690TT or I 800 tubing materials. This paper gives an overview of the 2006 revision of the VGB Water Chemistry Guidelines for PWR plants and describes the fundamental goals of water chemistry operation strategies. In addition, the reasons for the selected control parameters and action levels, to achieve an adequate plant performance, are presented based on the operating experience. (orig.)

  8. Fragmentation of rotating protostellar clouds

    International Nuclear Information System (INIS)

    Tohline, J.E.

    1980-01-01

    We examine, with a three-dimensional hydrodynamic computer code, the behavior of rotating, isothermal gas clouds as they collapse from Jeans unstable configurations, in order to determine whether they are susceptible to fragmentation during the initial dynamic collapse phase of their evolution. We find that a gas cloud will not fragment unless (a) it begins collapsing from a radius much smaller than the Jeans radius (i.e., the cloud initially encloses many Jeans masses) and (b) irregularities in the cloud's initial structure (specifically, density inhomogeneities) enclose more than one Jeans mass of material. Gas pressure smooths out features that are not initially Jeans unstable while rotation plays no direct role in damping inhomogeneities. Instead of fragmenting, most of our models collapse to a ring configuration (as has been observed by other investigators in two-dimensional, axisymmetric models). The rings appear to be less susceptible to gragmentation from arbitrary perturbations in their structure than has previously been indicated in other work. Because our models, which include the effects of gas pressure, do not readily fragment during a phase of dynamic collapse, we suggest that gas clouds in the galactic disk undergo fragmentation only during quasi-equilibrium phases of their evolution

  9. Fragment-based approaches to TB drugs.

    Science.gov (United States)

    Marchetti, Chiara; Chan, Daniel S H; Coyne, Anthony G; Abell, Chris

    2018-02-01

    Tuberculosis is an infectious disease associated with significant mortality and morbidity worldwide, particularly in developing countries. The rise of antibiotic resistance in Mycobacterium tuberculosis (Mtb) urgently demands the development of new drug leads to tackle resistant strains. Fragment-based methods have recently emerged at the forefront of pharmaceutical development as a means to generate more effective lead structures, via the identification of fragment molecules that form weak but high quality interactions with the target biomolecule and subsequent fragment optimization. This review highlights a number of novel inhibitors of Mtb targets that have been developed through fragment-based approaches in recent years.

  10. Analytical Chemistry as Methodology in Modern Pure and Applied Chemistry

    OpenAIRE

    Honjo, Takaharu

    2001-01-01

    Analytical chemistry is an indispensable methodology in pure and applied chemistry, which is often compared to a foundation stone of architecture. In the home page of jsac, it is said that analytical chemistry is a learning of basic science, which treats the development of method in order to get usefull chemical information of materials by means of detection, separation, and characterization. Analytical chemistry has recently developed into analytical sciences, which treats not only analysis ...

  11. The Zero-Degree Detector system for fragmentation studies

    International Nuclear Information System (INIS)

    Adams, J.H.; Christl, M.J.; Howell, L.W.; Kuznetsov, E.

    2007-01-01

    The measurement of nuclear fragmentation cross-sections requires the detection and identification of individual projectile fragments. If light and heavy fragments are recorded in the same detector, it may be impossible to distinguish the signal from the light fragment. To overcome this problem, we have developed the Zero-degree Detector System (ZDDS). The ZDDS enables the measurement of cross-sections for light fragment production by using pixelated detectors to separately measure the signals of each fragment. The system has been used to measure the fragmentation of beams as heavy as Fe at the NASA Space Radiation Laboratory at Brookhaven National Laboratory and the Heavy Ion Medical Accelerator in Chiba, Japan

  12. Fundamentals of nuclear chemistry

    International Nuclear Information System (INIS)

    Majer, K.

    1982-01-01

    The textbook is a Czech-to-German translation of the second revised edition and covers the subject under the headings: general nuclear chemistry, methods of nuclear chemistry, preparative nuclear chemistry, analytical nuclear chemistry, and applied chemistry. The book is especially directed to students

  13. Statistical applications for chemistry, manufacturing and controls (CMC) in the pharmaceutical industry

    CERN Document Server

    Burdick, Richard K; Pfahler, Lori B; Quiroz, Jorge; Sidor, Leslie; Vukovinsky, Kimberly; Zhang, Lanju

    2017-01-01

    This book examines statistical techniques that are critically important to Chemistry, Manufacturing, and Control (CMC) activities. Statistical methods are presented with a focus on applications unique to the CMC in the pharmaceutical industry. The target audience consists of statisticians and other scientists who are responsible for performing statistical analyses within a CMC environment. Basic statistical concepts are addressed in Chapter 2 followed by applications to specific topics related to development and manufacturing. The mathematical level assumes an elementary understanding of statistical methods. The ability to use Excel or statistical packages such as Minitab, JMP, SAS, or R will provide more value to the reader. The motivation for this book came from an American Association of Pharmaceutical Scientists (AAPS) short course on statistical methods applied to CMC applications presented by four of the authors. One of the course participants asked us for a good reference book, and the only book recomm...

  14. Things fall apart: Fragmentation reactions in the oxidative aging of organic species

    Science.gov (United States)

    Kroll, J. H.; Isaacman-VanWertz, G. A.; Wilson, K. R.; Daumit, K. E.; Kessler, S. H.; Lim, C. Y.; Worsnop, D. R.

    2016-12-01

    The atmospheric oxidation of organic compounds involves a wide array of chemical transformations, including functionalization reactions (addition of polar functional groups to the carbon skeleton), fragmentation reactions (formation of lower carbon-number products via C-C bond scission), and accretion reactions (increases in molecular weight by the combination of two chemical species). Each of these reaction classes can lead to large changes in volatility, and hence can have major implications for atmospheric organic aerosol (OA). For example, the formation of OA is predominantly driven by functionalization and accretion reactions, which generally lead to decreases in volatility. Here we describe a series of laboratory studies of the subsequent organic "aging", the multiday oxidation processes that occur after the initial OA formation and growth. In these studies, the multigenerational oxidation of organic compounds in various phases (the gas phase, the condensed OA phase, and the aqueous phase) is carried out within either an environmental chamber or a flow reactor, and monitored using various high-resolution mass spectrometric techniques. In all cases it is found that fragmentation reactions play a major role in the observed aging chemistry, dominated by the formation of small, volatile oxidation products. These results suggest that multi-day oxidative aging processes do not lead to sustained aerosol growth, but rather may serve as a chemical sink for atmospheric OA.

  15. Actinide chemistry in the far field

    International Nuclear Information System (INIS)

    Livens, F.R.; Morris, K.; Parkman, R.; Moyes, L.

    1996-01-01

    The environmental chemistry of the actinides is complicated due both to the extensive redox and coordination chemistry of the elements and also to the complexity of the reactive phases encountered in natural environments. In the far field, interactions with reactive surfaces, coatings and colloidal particles will play a crucial role in controlling actinide mobility. By virtue of both their abundance and reactivity; clays and other layer aluminosilicate minerals, hydrous oxides and organic matter (humic substances) are all identified as having the potential to react with actinide ions and some possible modes of interaction are described, together with experimental evidence for their occurrence. (author)

  16. Chemistry in power plants 2010. Lectures

    International Nuclear Information System (INIS)

    2010-01-01

    This year's conference starts with the analytical control of lubricating and hydraulic oil in turbine machines as well as with sampling and analysis in the water steam cycle. Other papers are dealing with the analysis of film-forming amines, the transformation of data from the water steam cycle into information for action, the improvement of water steam cycle chemistry in cyclic operation and finally the environmental application of closed loop recycling methods avoiding the discharge of waste water. Furthermore items of nuclear power plant chemistry as well as of flue gas cleaning and coal analysis are presented in two sections. [de

  17. Introduction to fragment-based drug discovery.

    Science.gov (United States)

    Erlanson, Daniel A

    2012-01-01

    Fragment-based drug discovery (FBDD) has emerged in the past decade as a powerful tool for discovering drug leads. The approach first identifies starting points: very small molecules (fragments) that are about half the size of typical drugs. These fragments are then expanded or linked together to generate drug leads. Although the origins of the technique date back some 30 years, it was only in the mid-1990s that experimental techniques became sufficiently sensitive and rapid for the concept to be become practical. Since that time, the field has exploded: FBDD has played a role in discovery of at least 18 drugs that have entered the clinic, and practitioners of FBDD can be found throughout the world in both academia and industry. Literally dozens of reviews have been published on various aspects of FBDD or on the field as a whole, as have three books (Jahnke and Erlanson, Fragment-based approaches in drug discovery, 2006; Zartler and Shapiro, Fragment-based drug discovery: a practical approach, 2008; Kuo, Fragment based drug design: tools, practical approaches, and examples, 2011). However, this chapter will assume that the reader is approaching the field with little prior knowledge. It will introduce some of the key concepts, set the stage for the chapters to follow, and demonstrate how X-ray crystallography plays a central role in fragment identification and advancement.

  18. Mechanisms Affecting Population Density in Fragmented Habitat

    Directory of Open Access Journals (Sweden)

    Lutz Tischendorf

    2005-06-01

    Full Text Available We conducted a factorial simulation experiment to analyze the relative importance of movement pattern, boundary-crossing probability, and mortality in habitat and matrix on population density, and its dependency on habitat fragmentation, as well as inter-patch distance. We also examined how the initial response of a species to a fragmentation event may affect our observations of population density in post-fragmentation experiments. We found that the boundary-crossing probability from habitat to matrix, which partly determines the emigration rate, is the most important determinant for population density within habitat patches. The probability of crossing a boundary from matrix to habitat had a weaker, but positive, effect on population density. Movement behavior in habitat had a stronger effect on population density than movement behavior in matrix. Habitat fragmentation and inter-patch distance may have a positive or negative effect on population density. The direction of both effects depends on two factors. First, when the boundary-crossing probability from habitat to matrix is high, population density may decline with increasing habitat fragmentation. Conversely, for species with a high matrix-to-habitat boundary-crossing probability, population density may increase with increasing habitat fragmentation. Second, the initial distribution of individuals across the landscape: we found that habitat fragmentation and inter-patch distance were positively correlated with population density when individuals were distributed across matrix and habitat at the beginning of our simulation experiments. The direction of these relationships changed to negative when individuals were initially distributed across habitat only. Our findings imply that the speed of the initial response of organisms to habitat fragmentation events may determine the direction of observed relationships between habitat fragmentation and population density. The time scale of post-fragmentation

  19. Surface chemistry essentials

    CERN Document Server

    Birdi, K S

    2013-01-01

    Surface chemistry plays an important role in everyday life, as the basis for many phenomena as well as technological applications. Common examples range from soap bubbles, foam, and raindrops to cosmetics, paint, adhesives, and pharmaceuticals. Additional areas that rely on surface chemistry include modern nanotechnology, medical diagnostics, and drug delivery. There is extensive literature on this subject, but most chemistry books only devote one or two chapters to it. Surface Chemistry Essentials fills a need for a reference that brings together the fundamental aspects of surface chemistry w

  20. Inferior patellar pole fragmentation in children: just a normal variant?

    Energy Technology Data Exchange (ETDEWEB)

    Kan, J.H.; Vogelius, Esben S.; Orth, Robert C.; Guillerman, R.P.; Jadhav, Siddharth P. [Texas Children' s Hospital, E.B. Singleton Pediatric Radiology, Houston, TX (United States)

    2015-06-15

    Fragmentary ossification of the inferior patella is often dismissed as a normal variant in children younger than 10 years of age. The purpose of this study was to determine whether fragmentary inferior patellar pole ossification is a normal variant or is associated with symptoms or signs of pathology using MRI and clinical exam findings as reference. A retrospective review was performed on 150 patients ages 5-10 years who underwent 164 knee radiography and MRI exams (45.1% male, mean age: 7.8 years). The presence or absence of inferior patellar pole fragmentation on radiography was correlated with the presence or absence of edema-like signal on MR images. Clinical notes were reviewed for the presence of symptoms or signs referable to the inferior patellar pole. These data were compared with a 1:1 age- and sex-matched control group without inferior pole fragmentation. Statistical analysis was performed using two-tailed t-tests. Forty of 164 (24.4%) knee radiographs showed fragmentary ossification of the inferior patella. Of these 40 knees, 62.5% (25/40) had edema-like signal of the inferior patellar bone marrow compared with 7.5% (3/40) of controls (P = 0.035). Patients with fragmentary ossification at the inferior patella had a significantly higher incidence of documented focal inferior patellar pain compared with controls (20% vs. 2.5%, P = 0.015). Inferior patellar pole fragmentation in children 5 to 10 years of age may be associated with localized symptoms and bone marrow edema-like signal and should not be routinely dismissed as a normal variant of ossification. (orig.)

  1. An Alternative Quality Control Technique for Mineral Chemistry Analysis of Portland Cement-Grade Limestone Using Shortwave Infrared Spectroscopy

    Directory of Open Access Journals (Sweden)

    Nasrullah Zaini

    2016-11-01

    Full Text Available Shortwave infrared (SWIR spectroscopy can be applied directly to analyze the mineral chemistry of raw or geologic materials. It provides diagnostic spectral characteristics of the chemical composition of minerals, information that is invaluable for the identification and quality control of such materials. The present study aims to investigate the potential of SWIR spectroscopy as an alternative quality control technique for the mineral chemistry analysis of Portland cement-grade limestone. We used the spectroscopic (wavelength position and depth of absorption feature and geochemical characteristics of limestone samples to estimate the abundance and composition of carbonate and clay minerals on rock surfaces. The depth of the carbonate (CO3 and Al-OH absorption features are linearly correlated with the contents of CaO and Al2O3 in the samples, respectively, as determined by portable X-ray fluorescence (PXRF measurements. Variations in the wavelength position of CO3 and Al-OH absorption features are related to changes in the chemical compositions of the samples. The results showed that the dark gray and light gray limestone samples are better suited for manufacturing Portland cement clinker than the dolomitic limestone samples. This finding is based on the CaO, MgO, Al2O3, and SiO2 concentrations and compositions. The results indicate that SWIR spectroscopy is an appropriate approach for the chemical quality control of cement raw materials.

  2. Nuclear analytical chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Brune, D.; Forkman, B.; Persson, B.

    1984-01-01

    This book covers the general theories and techniques of nuclear chemical analysis, directed at applications in analytical chemistry, nuclear medicine, radiophysics, agriculture, environmental sciences, geological exploration, industrial process control, etc. The main principles of nuclear physics and nuclear detection on which the analysis is based are briefly outlined. An attempt is made to emphasise the fundamentals of activation analysis, detection and activation methods, as well as their applications. The book provides guidance in analytical chemistry, agriculture, environmental and biomedical sciences, etc. The contents include: the nuclear periodic system; nuclear decay; nuclear reactions; nuclear radiation sources; interaction of radiation with matter; principles of radiation detectors; nuclear electronics; statistical methods and spectral analysis; methods of radiation detection; neutron activation analysis; charged particle activation analysis; photon activation analysis; sample preparation and chemical separation; nuclear chemical analysis in biological and medical research; the use of nuclear chemical analysis in the field of criminology; nuclear chemical analysis in environmental sciences, geology and mineral exploration; and radiation protection.

  3. Nuclear analytical chemistry

    International Nuclear Information System (INIS)

    Brune, D.; Forkman, B.; Persson, B.

    1984-01-01

    This book covers the general theories and techniques of nuclear chemical analysis, directed at applications in analytical chemistry, nuclear medicine, radiophysics, agriculture, environmental sciences, geological exploration, industrial process control, etc. The main principles of nuclear physics and nuclear detection on which the analysis is based are briefly outlined. An attempt is made to emphasise the fundamentals of activation analysis, detection and activation methods, as well as their applications. The book provides guidance in analytical chemistry, agriculture, environmental and biomedical sciences, etc. The contents include: the nuclear periodic system; nuclear decay; nuclear reactions; nuclear radiation sources; interaction of radiation with matter; principles of radiation detectors; nuclear electronics; statistical methods and spectral analysis; methods of radiation detection; neutron activation analysis; charged particle activation analysis; photon activation analysis; sample preparation and chemical separation; nuclear chemical analysis in biological and medical research; the use of nuclear chemical analysis in the field of criminology; nuclear chemical analysis in environmental sciences, geology and mineral exploration; and radiation protection

  4. Storm-generated coral fragments - A viable source of transplants for reef rehabilitation

    Science.gov (United States)

    Garrison, V.; Ward, G.

    2008-01-01

    Coral reefs throughout the world have been damaged by storms, diseases, coral predators, temperature anomalies, and human activities. During the past three decades, recovery has been limited and patchy. Although a damaged coral reef cannot be restored to its original condition, interest in reef restoration is increasing. In a pilot project in the Caribbean (US Virgin Islands), storm-produced fragments of Acropora palmata, A. cervicornis, and Porites porites were collected from donor reefs and transplanted to nearby degraded reefs. Sixty coral fragments were attached to dead-coral substrate (usually A. palmata skeletons), at similar depths from which they had been collected (1-3.5 m), using nylon cable ties. Seventy-five intact colonies were designated as controls. Study colonies were assessed at 6-month intervals for 2 years (1999-2001) and annually thereafter (through 2004). One-fourth of the 135 colonies and fragments monitored were alive at the conclusion of the 5-year study. Survival of control and transplanted A. cervicornis and P. porites was very low (median survival 2.4 and 1.8 years, respectively), with no significant differences between transplant and control colonies. Site and depth did not contribute significantly to A. palmata colony survival, but colony size and transplant/control status did. Probability of survival increased with colony size. Median survival for A. palmata was 1.3 years for transplant and 4.3 years for natural colonies when not controlled for size. A. palmata was the only viable candidate for reef rehabilitation. Storm swells were the primary cause of mortality.

  5. Quark fragmentation in e+e- collisions

    International Nuclear Information System (INIS)

    Oddone, P.

    1984-12-01

    This brief review of new results in quark and gluon fragmentation observed in e + e - collisions concentrates mostly on PEP results and, within PEP, mostly on TPC results. The new PETRA results have been reported at this conference by M. Davier. It is restricted to results on light quark fragmentation since the results on heavy quark fragmentation have been reported by J. Chapman

  6. The New Color of Chemistry: Green Chemistry

    Directory of Open Access Journals (Sweden)

    Zuhal GERÇEK

    2012-01-01

    Full Text Available Green chemistry which is the new application of chemistry rules provides solutions to problems that mankind is faced with climate changes, sustainable agriculture, energy, toxics, depletion of natural sources e.g. designing new chemicals and processes that production and utilization of hazardous matters. So, it is the indispensible tool for sustainable development. Current and future chemists should consider the human health and ecological issues in their professional life. In order to provide a solution for this requirement, green chemistry rules and under standings should be primarily taken in the university curriculum and at all educational levels.

  7. Detection of Alkynes via Click Chemistry with a Brominated Coumarin Azide by Simultaneous Fluorescence and Isotopic Signatures in Mass Spectrometry.

    Science.gov (United States)

    Yang, Lihua; Chumsae, Chris; Kaplan, Jenifer B; Moulton, Kevin Ryan; Wang, Dongdong; Lee, David H; Zhou, Zhaohui Sunny

    2017-09-20

    Alkynes are a key component of click chemistry and used for a wide variety of applications including bioconjugation, selective tagging of protein modifications, and labeling of metabolites and drug targets. However, challenges still exist for detecting alkynes because most 1,2,3-triazole products from alkynes and azides do not possess distinct intrinsic properties that can be used for their facile detection by either fluorescence or mass spectrometry. To address this critical need, a novel brominated coumarin azide was used to tag alkynes and detect alkyne-conjugated biomolecules. This tag has several useful properties: first, it is fluorogenic and the click-chemistry products are highly fluorescent and quantifiable; second, its distinct isotopic pattern facilitates identification by mass spectrometry; and third, its click-chemistry products form a unique pair of reporter ions upon fragmentation that can be used for the quick screening of data. Using a monoclonal antibody conjugated with alkynes, a general workflow has been developed and examined comprehensively.

  8. Rule of five in 2015 and beyond: Target and ligand structural limitations, ligand chemistry structure and drug discovery project decisions.

    Science.gov (United States)

    Lipinski, Christopher A

    2016-06-01

    The rule of five (Ro5), based on physicochemical profiles of phase II drugs, is consistent with structural limitations in protein targets and the drug target ligands. Three of four parameters in Ro5 are fundamental to the structure of both target and drug binding sites. The chemical structure of the drug ligand depends on the ligand chemistry and design philosophy. Two extremes of chemical structure and design philosophy exist; ligands constructed in the medicinal chemistry synthesis laboratory without input from natural selection and natural product (NP) metabolites biosynthesized based on evolutionary selection. Exceptions to Ro5 are found mostly among NPs. Chemistry chameleon-like behavior of some NPs due to intra-molecular hydrogen bonding as exemplified by cyclosporine A is a strong contributor to NP Ro5 outliers. The fragment derived, drug Navitoclax is an example of the extensive expertise, resources, time and key decisions required for the rare discovery of a non-NP Ro5 outlier. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Fragmentation of a 500 MeV/nucleon 86Kr beam, investigated at the GSI projectile fragment separator

    International Nuclear Information System (INIS)

    Weber, M.; Donzaud, C.; Geissel, H.; Grewe, A.; Lewitowicz, M.; Magel, A.; Mueller, A.C.; Nickel, F.; Pfuetzner, M.; Piechaczek, A.; Pravikoff, M.; Roeckl, E.; Rykaczewski, K.; Saint-Laurent, M.G.; Schall, I.; Stephan, C.; Tassan-Got, L.; Voss, B.

    1993-10-01

    Production cross-sections and longitudinal momentum distributions have been investigated for reactions between a 500 MeV/nucleon 86 Kr beam and beryllium, copper and tantalum targets. Fragments in a wide A/Z range were studied at the projectile-fragment separator FRS at GSI. The experimental production cross-sections have been used for testing the predictions obtained from a semi-empirical parameterization, a statistical abrasion model and an intranuclear-cascade model. The present study allows to extrapolate the production cross-sections towards very neutron-rich isotopes such as the doubly magic nucleus 78 Ni. For fragments close to the projectile the measured longitudinal momentum distributions agrees qualitatively with a semi-empirical parameterization, which is based on the two-step picture of the fragmentation process. The momentum widths of lighter fragments, however, show deviations from this simple picture. (orig.)

  10. Chemistry of Technetium

    International Nuclear Information System (INIS)

    Omori, Takashi

    2001-01-01

    Since the late 1970's the coordination chemistry of technetium has been developed remarkably. The background of the development is obviously related to the use of technetium radiopharmaceuticals for diagnosis in nuclear medicine. Much attention has also been denoted to the chemical behavior of environmental 99 Tc released from reprocessing plants. This review covers the several aspects of technetium chemistry, including production of radioisotopes, analytical chemistry and coordination chemistry. In the analytical chemistry, separation of technetium, emphasizing chromatography and solvent extraction, is described together with spectrophotometric determination of technetium. In the coordination chemistry of technetium, a characteristic feature of the chemistry of Tc(V) complexes is referred from the view point of the formation of a wide variety of highly stable complexes containing the Tc=O or Tc≡N bond. Kinetic studies of the preparation of Tc(III) complexes using hexakis (thiourea) technetium(III) ion as a starting material are summarized, together with the base hydrolysis reactions of Tc(III), Tc(IV) and Tc(V) complexes. (author)

  11. Ternary-fragmentation-driving potential energies of 252Cf

    Science.gov (United States)

    Karthikraj, C.; Ren, Zhongzhou

    2017-12-01

    Within the framework of a simple macroscopic model, the ternary-fragmentation-driving potential energies of 252Cf are studied. In this work, all possible ternary-fragment combinations of 252Cf are generated by the use of atomic mass evaluation-2016 (AME2016) data and these combinations are minimized by using a two-dimensional minimization approach. This minimization process can be done in two ways: (i) with respect to proton numbers (Z1, Z2, Z3) and (ii) with respect to neutron numbers (N1, N2, N3) of the ternary fragments. In this paper, the driving potential energies for the ternary breakup of 252Cf are presented for both the spherical and deformed as well as the proton-minimized and neutron-minimized ternary fragments. From the proton-minimized spherical ternary fragments, we have obtained different possible ternary configurations with a minimum driving potential, in particular, the experimental expectation of Sn + Ni + Ca ternary fragmentation. However, the neutron-minimized ternary fragments exhibit a driving potential minimum in the true-ternary-fission (TTF) region as well. Further, the Q -value energy systematics of the neutron-minimized ternary fragments show larger values for the TTF fragments. From this, we have concluded that the TTF region fragments with the least driving potential and high Q values have a strong possibility in the ternary fragmentation of 252Cf. Further, the role of ground-state deformations (β2, β3, β4, and β6) in the ternary breakup of 252Cf is also studied. The deformed ternary fragmentation, which involves Z3=12 -19 fragments, possesses the driving potential minimum due to the larger oblate deformations. We also found that the ground-state deformations, particularly β2, strongly influence the driving potential energies and play a major role in determining the most probable fragment combinations in the ternary breakup of 252Cf.

  12. Architectural fragments

    DEFF Research Database (Denmark)

    Bang, Jacob Sebastian

    2018-01-01

    I have created a large collection of plaster models: a collection of Obstructions, errors and opportunities that may develop into architecture. The models are fragments of different complex shapes as well as more simple circular models with different profiling and diameters. In this contect I have....... I try to invent the ways of drawing the models - that decode and unfold them into architectural fragments- into future buildings or constructions in the landscape. [1] Luigi Moretti: Italian architect, 1907 - 1973 [2] Man Ray: American artist, 1890 - 1976. in 2015, I saw the wonderful exhibition...... "Man Ray - Human Equations" at the Glyptotek in Copenhagen, organized by the Philips Collection in Washington D.C. and the Israel Museum in Jerusalem (in 2013). See also: "Man Ray - Human Equations" catalogue published by Hatje Cantz Verlag, Germany, 2014....

  13. Highly efficient reversible addition-fragmentation chain-transfer polymerization in ethanol/water via flow chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Ye, Piaoran [Case Western Reserve Univ., Cleveland, OH (United States); Cao, Peng -Fei [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Su, Zhe [Case Western Reserve Univ., Cleveland, OH (United States); Advincula, Rigoberto [Case Western Reserve Univ., Cleveland, OH (United States)

    2017-03-23

    Here, utilization of a flow reactor under high pressure allows highly efficient polymer synthesis via reversible addition–fragmentation chain-transfer (RAFT) polymerization in an aqueous system. Compared with the batch reaction, the flow reactor allows the RAFT polymerization to be performed in a high-efficiency manner at the same temperature. The adjustable pressure of the system allows further elevation of the reaction temperature and hence faster polymerization. Other reaction parameters, such as flow rate and initiator concentration, were also well studied to tune the monomer conversion and the molar mass dispersity (Ð) of the obtained polymers. Gel permeation chromatography, nuclear magnetic resonance (NMR), and Fourier transform infrared spectroscopies (FTIR) were utilized to monitor the polymerization process. With the initiator concentration of 0.15 mmol L–1, polymerization of poly(ethylene glycol) methyl ethermethacrylate with monomer conversion of 52% at 100 °C under 73 bar can be achieved within 40 min with narrow molar mass dispersity (D) Ð (<1.25). The strategy developed here provides a method to produce well-defined polymers via RAFT polymerization with high efficiency in a continuous manner.

  14. Institute of Nuclear Chemistry and Technology annual report 1995

    International Nuclear Information System (INIS)

    1996-01-01

    The report is a collection of short communications being a review of scientific activity of the Institute of Nuclear Chemistry and Technology (INCT), Warsaw, in 1995. The papers are gathered in several branches as follows: radiation chemistry and physics (15); radiochemistry, stable isotopes, nuclear analytical methods, chemistry in general (23); radiobiology (7); nuclear technologies and methods (21); nucleonic control systems (5). The Annual Report of INCT - 1995 contains also a general information about the staff and organization of the Institute, the full list of scientific publications and patents, conferences organized by INCT, thesis and list of projects granted by Polish and international organizations

  15. Institute of Nuclear Chemistry and Technology annual report 1995

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-31

    The report is a collection of short communications being a review of scientific activity of the Institute of Nuclear Chemistry and Technology (INCT), Warsaw, in 1995. The papers are gathered in several branches as follows: radiation chemistry and physics (15); radiochemistry, stable isotopes, nuclear analytical methods, chemistry in general (23); radiobiology (7); nuclear technologies and methods (21); nucleonic control systems (5). The Annual Report of INCT - 1995 contains also a general information about the staff and organization of the Institute, the full list of scientific publications and patents, conferences organized by INCT, thesis and list of projects granted by Polish and international organizations.

  16. Institute of Nuclear Chemistry and Technology annual report 1995

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    The report is a collection of short communications being a review of scientific activity of the Institute of Nuclear Chemistry and Technology (INCT), Warsaw, in 1995. The papers are gathered in several branches as follows: radiation chemistry and physics (15); radiochemistry, stable isotopes, nuclear analytical methods, chemistry in general (23); radiobiology (7); nuclear technologies and methods (21); nucleonic control systems (5). The Annual Report of INCT - 1995 contains also a general information about the staff and organization of the Institute, the full list of scientific publications and patents, conferences organized by INCT, thesis and list of projects granted by Polish and international organizations.

  17. Secondary water chemistry control practices and results of the Japanese PWR plants

    International Nuclear Information System (INIS)

    Maeda, Akihiro; Shoda, Yasuhiko; Ishihara, Nobuo; Murata, Kazutoyo; Fujiwara, Hiroyuki; Hayakawa, Hitoshi; Matsuda, Tadashi

    2012-09-01

    In Japan, since the start of the operation of the first PWR plant, Mihama Unit-1 in 1970, 24 PWR plants have been built by 2010, and all of them are in operation. Due to the plant-specific needs of management, and by flexibly incorporating the state-of-the-art insights into the design, the system configurations of the plants vary so many as 15 types. Meanwhile, the geographical feature of Japan makes all the Japanese PWR plants to have condensers cooled by sea water, and all the plants have a common system with a full-flow Condensate Polisher System (CPS). To prevent corrosion, continued improvements of the secondary water chemistry management has been performed like other countries, and one of the major features of the Japanese PWR plants is an enhanced provision for the condenser leakage. The water quality of SG (Steam Generator) has been significantly improved by the provision for the sea water leakage, in combination with other improvements in water chemistry management. Also in Japan, almost all of the treatments of the spent polisher resin and the wastewater are performed within the power plant sites. To facilitate the treatment of the waste water and the regeneration of the spent resins, either ammonia or ETA (Ethanol Amine) is selected as the pH adjustment agent for the secondary system water. Also at the ammonia treatment, high pH accomplishes the inhibition of the piping wall thinning and the lower iron transportation into SGs. In addition, the iron transported into the SG is removed by the chemical conditioning treatment called ASCA (Advanced Scale Conditioning Agent). This provides the effective recovery of the SG heat-transfer performance, and the improved SG support plate BEC (Broached Egg Crate) hole blockage rates. Basically in Japan, the secondary water chemistry management has been improved based on a single basic specification, for the variety of the plant configurations, with the plant-specific investigations and analyses. This paper summarizes

  18. Loneliness is associated with sleep fragmentation in a communal society.

    Science.gov (United States)

    Kurina, Lianne M; Knutson, Kristen L; Hawkley, Louise C; Cacioppo, John T; Lauderdale, Diane S; Ober, Carole

    2011-11-01

    Loneliness has been shown to predict poor health. One hypothesized mechanism is that lonely individuals do not sleep as well as individuals who feel more connected to others. Our goal was to test whether loneliness is associated with sleep fragmentation or sleep duration. Cross-sectional study. Members of a traditional, communal, agrarian society living in South Dakota. Ninety-five participants (mean age 39.8 years, 55% female) who were ≥ 19 years of age at the study's inception. Not applicable. We conducted interviews querying loneliness, depression, anxiety, and stress, as well as subjective sleep quality and daytime sleepiness. Study participants wore a wrist actigraph for one week to measure objective sleep properties; the two studied here were sleep fragmentation and sleep duration. Higher loneliness scores were associated with significantly higher levels of sleep fragmentation (β = 0.073, t = 2.55, P = 0.01), controlling for age, sex, body mass index, risk of sleep apnea, and negative affect (a factor comprising symptoms of depression and anxiety, and perceived stress). Loneliness was not associated with sleep duration or with either subjective sleep measure. Loneliness was a significant predictor of sleep fragmentation. Humans' social nature may partly be manifest through our dependence on feeling secure in our social environment to sleep well.

  19. Chemical Production using Fission Fragments

    International Nuclear Information System (INIS)

    Dawson, J. K.; Moseley, F.

    1960-01-01

    Some reactor design considerations of the use of fission recoil fragment energy for the production of chemicals of industrial importance have been discussed previously in a paper given at the Second United Nations International Conference on the Peaceful Uses of Atomic Energy [A/Conf. 15/P.76]. The present paper summarizes more recent progress made on this topic at AERE, Harwell. The range-energy relationship for fission fragments is discussed in the context of the choice of fuel system for a chemical production reactor, and the experimental observation of a variation of chemical effect along the length of a fission fragment track is described for the irradiation of nitrogen-oxygen mixtures. Recent results are given on the effect of fission fragments on carbon monoxide-hydrogen gas mixtures and on water vapour. No system investigated to date shows any outstanding promise for large-scale chemical production. (author) [fr

  20. The dynamics of fragment formation

    International Nuclear Information System (INIS)

    Keane, D.

    1994-09-01

    We demonstrate that in the Quantum Molecular Dynamics model, dynamical correlations can result in the production rate for final state nucleon clusters (and hence composite fragments) being higher than would be expected if statistics and the available phase space were dominant in determining composite formation. An intranuclear cascade or a Boltzmann-Uehling-Uhlenbeck model, combined with a statistical approach in the late stage of the collision to determine composites, provides an equivalent description only under limited conditions of centrality and beam energy. We use data on participant fragment production in Au + Au collisions in the Bevalac's BOS time projection chamber to map out the parameter space where statistical clustering provides a good description. In particular, we investigate momentum-space densities of fragments up to 4 He as a function of fragment transverse momentum, azimuth relative to the reaction plane, rapidity, multiplicity and beam energy