Macropolyhedral boron-containing cluster chemistry [S2B16H17](-). A new eighteen-vertex thiaborane anion

Czech Academy of Sciences Publication Activity Database

Carr, MJ.; Clegg, W.; Kennedy, J.D.; Londesborough, Michael Geoffrey Stephen; Kilner, C. A.

2010-01-01

Roč. 75, č. 8 (2010), s. 807-812 ISSN 0010-0765 Institutional research plan: CEZ:AV0Z40320502 Keywords : borane cluster * thiaborane * macropolyhedral Subject RIV: CA - Inorganic Chemistry Impact factor: 0.853, year: 2010

The new Zintl phases Eu{sub 21}Cd{sub 4}Sb{sub 18} and Eu{sub 21}Mn{sub 4}Sb{sub 18}

Energy Technology Data Exchange (ETDEWEB)

Wang, Yi; Darone, Gregory M.; Bobev, Svilen, E-mail: bobev@udel.edu

2016-06-15

Crystals of two new Zintl compounds, Eu{sub 21}Mn{sub 4}Sb{sub 18} and Eu{sub 21}Cd{sub 4}Sb{sub 18} have been synthesized using the molten metal flux method, and their structures have been established by single-crystal X-ray diffraction. Both compounds are isotypic and crystallize in the monoclinic space group C2/m (No. 12, Z=4). The structures are based on edge- and corner-shared MnSb{sub 4} or CdSb{sub 4} tetrahedra, which make octameric [Mn{sub 8}Sb{sub 22}] or [Cd{sub 8}Sb{sub 22}] polyanions. Homoatomic Sb–Sb bonds are present in both structures. The Eu atoms take the role of Eu{sup 2+}cations with seven unpaired 4f electrons, as suggested by the temperature-dependent magnetization measurements. The magnetic susceptibilities of Eu{sub 21}Mn{sub 4}Sb{sub 18} and Eu{sub 21}Cd{sub 4}Sb{sub 18} indicate that both phases order anti-ferromagnetically with Néel temperatures of ca. 7 K and ca. 10 K, respectively. The unpaired 3d electrons of the Mn atoms in Eu{sub 21}Mn{sub 4}Sb{sub 18} do contribute to the magnetic response, however, the bulk magnetization measurements do not provide evidence for long-range ordering of the Mn spins down to 5 K. Electrical resistivity measurements suggest that both compounds are narrow band gap semiconductors. - Graphical abstract: Eu{sub 21}Mn{sub 4}Sb{sub 18} and Eu{sub 21}Cd{sub 4}Sb{sub 18} have complex monoclinic structures, based on MnSb{sub 4} and CdSb{sub 4} tetrahedra, both edge- and corner-shared. A perspective of the crystal structure is shown, as viewed along the b axis. Display Omitted - Highlights: • Eu{sub 21}Mn{sub 4}Sb{sub 18} and Eu{sub 21}Cd{sub 4}Sb{sub 18} are novel compounds in the respective ternary phase diagrams. • For both structures, the Zintl-Klemm rules are followed, and both are small gap semiconductors. • Eu{sub 21}Mn{sub 4}Sb{sub 18} and Eu{sub 21}Cd{sub 4}Sb{sub 18} are air-stable Zintl phases and could be new thermoelectric materials.

Role of protein-glutathione contacts in defining glutaredoxin-3 [2Fe-2S] cluster chirality, ligand exchange and transfer chemistry.

Science.gov (United States)

Sen, Sambuddha; Cowan, J A

2017-10-01

Monothiol glutaredoxins (Grx) serve as intermediate cluster carriers in iron-sulfur cluster trafficking. The [2Fe-2S]-bound holo forms of Grx proteins display cysteinyl coordination from exogenous glutathione (GSH), in addition to contact from protein-derived Cys. Herein, we report mechanistic studies that investigate the role of exogenous glutathione in defining cluster chirality, ligand exchange, and the cluster transfer chemistry of Saccharomyces cerevisiae Grx3. Systematic perturbations were introduced to the glutathione-binding site by substitution of conserved charged amino acids that form crucial electrostatic contacts with the glutathione molecule. Native Grx3 could also be reconstituted in the absence of glutathione, with either DTT, BME or free L-cysteine as the source of the exogenous Fe-S ligand contact, while retaining full functional reactivity. The delivery of the [2Fe-2S] cluster to Grx3 from cluster donor proteins such as Isa, Nfu, and a [2Fe-2S](GS) 4 complex, revealed that electrostatic contacts are of key importance for positioning the exogenous glutathione that in turn influences the chiral environment of the cluster. All Grx3 derivatives were reconstituted by standard chemical reconstitution protocols and found to transfer cluster to apo ferredoxin 1 (Fdx1) at rates comparable to native protein, even when using DTT, BME or free L-cysteine as a thiol source in place of GSH during reconstitution. Kinetic analysis of cluster transfer from holo derivatives to apo Fdx1 has led to a mechanistic model for cluster transfer chemistry of native holo Grx3, and identification of the likely rate-limiting step for the reaction.

First principles electronic structure and optical properties of the Zintl compound Eu3In2P4

KAUST Repository

Singh, Nirpendra; Schwingenschlö gl, Udo

2011-01-01

We have performed full-potential calculations of the electronic structure and optical properties of the newly found Zintl compound Eu3In 2P4. Eu3In2P4 turns out to be a small gap semiconductor with an energy gap of 0.42 eV, which is in agreement with the experimental value of 0.452 eV. The peaks of the optical spectra originate mainly from transitions between occupied Eu 4f states in the valence band and unoccupied Eu 5d states in the conduction band. A considerable anisotropy is observed for the parallel and perpendicular components in the frequency dependent optical spectra. The spectral features are explained in terms of the band structure. © 2011 Elsevier B.V. All rights reserved.

First principles electronic structure and optical properties of the Zintl compound Eu3In2P4

KAUST Repository

Singh, Nirpendra

2011-05-01

We have performed full-potential calculations of the electronic structure and optical properties of the newly found Zintl compound Eu3In 2P4. Eu3In2P4 turns out to be a small gap semiconductor with an energy gap of 0.42 eV, which is in agreement with the experimental value of 0.452 eV. The peaks of the optical spectra originate mainly from transitions between occupied Eu 4f states in the valence band and unoccupied Eu 5d states in the conduction band. A considerable anisotropy is observed for the parallel and perpendicular components in the frequency dependent optical spectra. The spectral features are explained in terms of the band structure. © 2011 Elsevier B.V. All rights reserved.

Linkage of molecular units in the chemistry of niobium and tantalum cluster halides

International Nuclear Information System (INIS)

Perrin, C.; Sergent, M.

1991-01-01

In low valency niobium and tantalum halides, interunit linkages are observed between the (Me 6 X 12 )X 6 units. They are insulators and interesting magnetic properties are observed, due to the intrinsic potential magnetism of the Me 6 cluster and depending on the inserted cations, for instance rare earths in MM'Nb 6 Cl 18 (M = monovalent cation, M' = rare earth). Of special interest are the niobium iodides which exhibit (Me 6 X 8 )X 6 units, an exception in the niobium chemistry; interesting properties have been reported for some of these iodides

Combining research in physical chemistry and chemical education: Part A. The femtosecond molecular dynamics of small gas-phase anion clusters. Part B. Surveying student beliefs about chemistry and the development of physical chemistry learning tutorials

Science.gov (United States)

Barbera, Jack

2007-12-01

This dissertation combines work in the areas of experimental physical chemistry and chemical education. In the area of physical chemistry, femtosecond pump-probe spectroscopy is used to interrogate the time-dependence for energy redistribution, solvent reorientation, and dissociation dynamics in small gas-phase anion clusters. The chemical education research addressed in this manuscript include the development and validation of a survey to measure students' beliefs about chemistry and the learning of chemistry and the development and testing of learning tutorials for use in undergraduate physical chemistry courses in thermodynamics and kinetics. In the first part of this dissertation, the Cu(CD3OD) dynamics are investigated using a combination of femtosecond pump-probe experiments and ab initio calculations. Dissociation of this complex into Cu and CD3OD occurs on two distinct time scales: 3 and 30 ps, which arise, respectively, from the coupling of intermolecular solvent rotations and excited methyl rotor rotation into the Cu-O dissociation component upon electron photodetachment of the precursor anion. In the second part of this dissertation, the time-resolved recombination of photodissociated IBr-(CO2)n (n = 5 - 10) cluster anions is investigated. Upon excitation to the A' 2pi 1/2 state of the chromophore, the bare anion results in I- and Br products, upon solvation with CO2, the IBr- chromophore regains near-IR absorption after recombination and vibrational relaxation on the ground electronic state. The recombination times vary with the number of solvent molecules from 12 ps for n = 5 to 900 ps for n = 10. Extensive electronic structure and non-adiabatic molecular dynamic simulations provide a framework to understand this behavior. In the third part of this dissertation, the modification and validation of the Colorado Learning Attitudes about Science Survey (CLASS) for use in chemistry is presented in detail. The CLASS survey is designed to measure student

Ba{sub 4}In{sub 8}Sb{sub 16}: Thermoelectric properties of a new layered Zintl phase with infinite zigzag Sb chains and pentagonal tubes

Energy Technology Data Exchange (ETDEWEB)

Kim, S J; Hu, S; Uher, C; Kanatzidis, M G

1999-11-01

A new Zintl phase Ba{sub 4}In{sub 8}Sb{sub 16} was obtained from a direct element combination reaction of the elements in a sealed graphite tube at 700 C, and its structure was determined by single-crystal X-ray diffraction methods. It crystallizes in the orthorhombic space group Pnma (No. 62) with a = 10.166(3) {angstrom}, b = 4.5239(14) {angstrom}, c = 19.495(6) {angstrom}, and Z = 1. Ba{sub 4}In{sub 8}Sb{sub 16} has a two-dimensional structure with thick corrugated (In{sub 8}Sb{sub 16}){sup 8{minus}} layers separated by Ba{sup 2+} ions. In the layer, InSb{sub 4} tetrahedra are connected by sharing three corners and by bridging the fourth corner in such a manner that infinite pentagonal tubes are formed. The compound is a narrow band gap ({approximately} 0.10 eV) semiconductor and satisfies the classical Zintl rule. Band structure calculations confirm that the material is a semiconductor and indicate that it has optimized In-Sb bonding interactions. Polycrystalline ingots of Ba{sub 4}In{sub 8}Sb{sub 16} show room-temperature electrical conductivity of 135 S/cm and a Seebeck coefficient of 70 {micro}V/K. The thermal conductivity of Ba{sub 4}In{sub 8}Sb{sub 16} is about 1.7 W/m{sm{underscore}bullet}K in the temperature range 150--300 K.

On clusters and clustering from atoms to fractals

CERN Document Server

Reynolds, PJ

1993-01-01

This book attempts to answer why there is so much interest in clusters. Clusters occur on all length scales, and as a result occur in a variety of fields. Clusters are interesting scientifically, but they also have important consequences technologically. The division of the book into three parts roughly separates the field into small, intermediate, and large-scale clusters. Small clusters are the regime of atomic and molecular physics and chemistry. The intermediate regime is the transitional regime, with its characteristics including the onset of bulk-like behavior, growth and aggregation, a

Role of the dimensionality of the [GaX]2 network in the Zintl phases EuGa2X2

KAUST Repository

Singh, Nirpendra

2012-11-28

The structural, electronic, magnetic, optical, and thermoelectric properties of EuGa2X2 (X = P, As, and Sb) are investigated using first principles calculations (taking into account the onsite Coulomb interaction) and the semi-classical Boltzmanntheory. The divalent nature of Eu fulfils the Zintl principle as is confirmed by the calculated total magnetic moments of ∼7 μB. A metallic behavior is obtained for all compounds. The optical spectra originate mainly from the transitions between occupied Eu 4f states and unoccupied Eu 5d states. It is demonstrated that the two-dimensional [Ga(P/As)]2 network in EuGa2P2 and EuGa2As2 is favorable for thermoelectric applications as compared to the three-dimensional [GaSb]2 network in EuGa2Sb2.

Bridging quantum chemistry and nuclear structure theory: Coupled-cluster calculations for closed- and open-shell nuclei

International Nuclear Information System (INIS)

Piecuch, Piotr; Wloch, Marta; Gour, Jeffrey R.; Dean, David J.; Papenbrock, Thomas; Hjorth-Jensen, Morten

2005-01-01

We review basic elements of the single-reference coupled-cluster theory and discuss large scale ab initio calculations of ground and excited states of 15O, 16O, and 17O using coupled-cluster methods and algorithms developed in quantum chemistry. By using realistic two-body interactions and the renormalized form of the Hamiltonian obtained with a no-core G-matrix approach, we obtain the converged results for 16O and promising preliminary results for 15O and 17O at the level of two-body interactions. The calculated properties other than energies include matter density, charge radius, and charge form factor. The relatively low costs of coupled-cluster calculations, which are characterized by the low-order polynomial scaling with the system size, enable us to probe large model spaces with up to 7 or 8 major oscillator shells, for which non-truncated shell-model calculations for nuclei with A = 15 17 active particles are presently not possible. We argue that the use of coupled-cluster methods and computer algorithms developed by quantum chemists to calculate properties of nuclei is an important step toward the development of accurate and affordable many-body theories that cross the boundaries of various physical sciences

Chemistry and kinetics of size-selected cobalt cluster cations at thermal energies. I. Reactions with CO

Science.gov (United States)

Guo, B. C.; Kerns, K. P.; Castleman, A. W., Jr.

1992-06-01

The chemistry and kinetics of size-selected Co+n cluster-ion (n=2-8) reactions with CO are studied using a selected ion drift tube affixed with a laser vaporization source operated under well-defined thermal conditions. All reactions studied in the present work are found to be association reactions. Their absolute rate constants, which are determined quantitatively, are found to have a strong dependence on cluster size. Similar to the cases of reactions with many other reactants such as H2 and CH4, Co+4 and Co+5 display a higher reactivity toward the CO molecule than do clusters of neighboring size. The multiple-collision conditions employed in the present work have enabled a determination of the maximum coordination number of CO molecules bound onto each Co+n cluster. It is found that the tetramer tends to bond 12 CO molecules, the pentamer 14 CO, hexamer 16 CO, and so on. The results are interpreted in terms of Lauher's calculation and the polyhedral skeletal electron pair theory. All the measured maximum coordination numbers correlate extremely well with the predictions of these theories, except for the trimer where the measured number is one CO less than the predicted value. The good agreement between experiment and theory enables one to gain some insight into the geometric structure of the clusters. Based on the present findings, the cobalt tetramer cation is interpreted to have a tetrahedral structure, the pentamer a trigonal bipyramid, and the hexamer an octahedral structure. Other cluster structures are also discussed.

Experimental studies of the chemistry of metal clusters

International Nuclear Information System (INIS)

Parks, E.K.; Riley, S.J.

1988-01-01

The procedures for studying chemical reactions of metal clusters in a continuous-flow reactor are described, and examples of such studies are given. Experiments to be discussed include kinetics and thermodynamics measurements, and determination of the composition of clusters saturated with various adsorbate reagents. Specific systems to be covered include the reaction of iron clusters with ammonia and with hydrogen, the reaction of nickel clusters with hydrogen and with ammonia, and the reaction of platinum clusters with ethylene. The last two reactions are characterized by complex, multi-step processes that lead to adsorbate decomposition and hydrogen desorption from the clusters. Methods for probing these processes will be discussed. 26 refs., 8 figs

Computational chemistry at the petascale: Are we there yet?

International Nuclear Information System (INIS)

Apra, E; Harrison, R J; Shelton, W A; Tipparaju, V; Vazquez-Mayagoitia, A

2009-01-01

We have run computational chemistry calculations approaching the Petascale level of performance (∼ 0.5 PFlops). We used the Coupled Cluster CCSD(T) module of the computational chemistry code NWChem to evaluate accurate energetics of water clusters on a 1.4 PFlops Cray XT5 computer.

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.

Electron-induced chemistry in microhydrated sulfuric acid clusters

Czech Academy of Sciences Publication Activity Database

Lengyel, Jozef; Pysanenko, Andriy; Fárník, Michal

2017-01-01

Roč. 17, č. 22 (2017), s. 14171-14180 ISSN 1680-7324 R&D Projects: GA ČR(CZ) GA17-04068S Grant - others:Austrian Science Fund (FWF)(AT) M1983-N34 Institutional support: RVO:61388955 Keywords : induced aerosol formation * particle formation * atmospheric implication Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry

From linking of metal-oxide building blocks in a dynamic library to giant clusters with unique properties and towards adaptive chemistry.

Science.gov (United States)

Müller, Achim; Gouzerh, Pierre

2012-11-21

Following Nature's lessons, today chemists can cross the boundary of the small molecule world to construct multifunctional and highly complex molecular nano-objects up to protein size and even cell-like nanosystems showing responsive sensing. Impressive examples emerge from studies of the solutions of some oxoanions of the early transition metals especially under reducing conditions which enable the controlled linking of metal-oxide building blocks. The latter are available from constitutional dynamic libraries, thus providing the option to generate multifunctional unique nanoscale molecular systems with exquisite architectures, which even opens the way towards adaptive and evolutive (Darwinian) chemistry. The present review presents the first comprehensive report of current knowledge (including synthesis aspects not discussed before) regarding the related giant metal-oxide clusters mainly of the type {Mo(57)M'(6)} (M' = Fe(III), V(IV)) (torus structure), {M(72)M'(30)} (M = Mo, M' = V(IV), Cr(III), Fe(III), Mo(V)), {M(72)Mo(60)} (M = Mo, W) (Keplerates), {Mo(154)}, {Mo(176)}, {Mo(248)} ("big wheels"), and {Mo(368)} ("blue lemon") - all having the important transferable pentagonal {(M)M(5)} groups in common. These discoveries expanded the frontiers of inorganic chemistry to the mesoscopic world, while there is probably no collection of discrete inorganic compounds which offers such a versatile chemistry and the option to study new phenomena of interdisciplinary interest. The variety of different properties of the sphere- and wheel-type metal-oxide-based clusters can directly be related to their unique architectures: The spherical Keplerate-type capsules having 20 crown-ether-type pores and tunable internal functionalities allow the investigation of confined matter as well as that of sphere-surface-supramolecular and encapsulation chemistry - including related new aspects of the biologically important hydrophobic effects - but also of nanoscale ion transport and

Journal of Chemical Sciences | Indian Academy of Sciences

Indian Academy of Sciences (India)

By utilizing L¹, a cationic 2D-MOF {[(L¹) ₂ (Cu₆I₅)](OH) · 3DMF·4MeOH}n, 1 containing a rugby ball shaped discrete Cu₆I₅ cluster has been reported earlier. Formation of a new 3D-MOF {[(L²) ₂ (Cu₆I₄)](OH) ₂· 2DMF}n containing a Zintl type [(Cu₆I₄4) ² ⁺]n cluster chains is reported in this paper. A neutral cluster MOFs ...

Amine reactivity with charged sulfuric acid clusters

Directory of Open Access Journals (Sweden)

B. R. Bzdek

2011-08-01

Full Text Available The distribution of charged species produced by electrospray of an ammonium sulfate solution in both positive and negative polarities is examined using Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS. Positively-charged ammonium bisulfate cluster composition differs significantly from negatively-charged cluster composition. For positively-charged clusters all sulfuric acid is neutralized to bisulfate, whereas for negatively-charged clusters the degree of sulfuric acid neutralization is cluster size-dependent. With increasing cluster size (and, therefore, a decreasing role of charge, both positively- and negatively-charged cluster compositions converge toward ammonium bisulfate. The reactivity of negatively-charged sulfuric acid-ammonia clusters with dimethylamine and ammonia is also investigated by FTICR-MS. Two series of negatively-charged clusters are investigated: [(HSO₄(H₂SO_4x]⁻ and [(NH_4x(HSO_4x+1(H₂SO₄₃]⁻. Dimethylamine substitution for ammonia in [(NH_{4 x}(HSO_{4 x+1}(H₂SO₄₃]⁻ clusters is nearly collision-limited, and subsequent addition of dimethylamine to neutralize H₂SO₄ to bisulfate is within one order of magnitude of the substitution rate. Dimethylamine addition to [(HSO₄ (H₂SO_{4 x}]⁻ clusters is either not observed or very slow. The results of this study indicate that amine chemistry will be evident and important only in large ambient negative ions (>m/z 400, whereas amine chemistry may be evident in small ambient positive ions. Addition of ammonia to unneutralized clusters occurs at a rate that is ~2–3 orders of magnitude slower than incorporation of dimethylamine either by substitution or addition

Eu9Cd4-xCM2+x-y□ySb9: Ca9Mn4Bi9-type structure stuffed with coinage metals (Cu, Ag, and Au) and the challenges with classical valence theory in describing these possible zintl phases.

Science.gov (United States)

Kazem, Nasrin; Hurtado, Antonio; Klobes, Benedikt; Hermann, Raphaël P; Kauzlarich, Susan M

2015-02-02

The synthesis, crystal structure, magnetic properties, and europium Mössbauer spectroscopy of the new members of the 9-4-9 Zintl family of Eu(9)Cd(4-x)CM(2+x-y)□(y)Sb(9) (CM = coinage metal: Au, Ag, and Cu) are reported. These compounds crystallize in the Ca(9)Mn(4)Bi(9) structure type (9-4-9) with the 4g interstitial site almost half-occupied by coinage metals; these are the first members in the 9-4-9 family where the interstitial positions are occupied by a monovalent metal. All previously known compounds with this structure type include divalent interstitials where these interstitials are typically the same as the transition metals in the anionic framework. Single-crystal magnetic susceptibility data indicate paramagnetic behavior for all three compounds with antiferromagnetic ordering below 10 K (at 100 Oe) that shifts to lower temperature (x)CM(2+x-y)□(y)Sb(9) at 50 and 6.5 K in order to evaluate the valence of Eu cations. Although the Zintl formalism states that the five crystallographically distinct Eu sites in Eu(9)Cd(4-x)CM(2+x-y)□(y)Sb9 should bear Eu(2+), the Mössbauer spectral isomer shifts are clearly indicative of both 2+ and 3+ valence of the Eu cations with the Cu- and Au-containing compounds showing higher amounts of Eu(3+). This electronic configuration leads to an excess of negative charge in these compounds that contradicts the expected valence-precise requirement of Zintl phases. The spectra obtained at 6.5 K reveal magnetic ordering for both Eu(2+) and Eu(3+). The field dependence of Eu(2+) indicates two distinct magnetic sublattices, with higher and lower fields, and of a small field for Eu(3+). The site symmetry of the five Eu sites is not distinguishable from the Mössbauer data.

High Eu 4f low-energy oscillator strength in the isostructural rare-earth Zintl compounds EuIn2X2 (X = P,As)

KAUST Repository

Singh, Nirpendra

2012-04-11

The isostructral Zintl compounds EuIn2X2 (X = P,As) are investigated within density functional theory. We employ the local spin density approximation with onsite interaction (LSDA + U) for varying U from 0 eV to 7 eV to model the Coulomb repulsion of the Eu 4f electrons. The LSDA + U optical conductivity disagrees with the experimental spectrum, while the simple LSDA is successful. Contrary to the expectation, it is found that EuIn2X2 (X = P,As) has a large oscillator strength for the f → d transitions in the low-energy range (below 1.5 eV) in which effects of the joint density of states play a key role. The materials show a sizeable magneto-optical Kerr effect.

High Eu 4f low-energy oscillator strength in the isostructural rare-earth Zintl compounds EuIn2X2 (X = P,As)

KAUST Repository

Singh, Nirpendra; Schwingenschlö gl, Udo

2012-01-01

The isostructral Zintl compounds EuIn2X2 (X = P,As) are investigated within density functional theory. We employ the local spin density approximation with onsite interaction (LSDA + U) for varying U from 0 eV to 7 eV to model the Coulomb repulsion of the Eu 4f electrons. The LSDA + U optical conductivity disagrees with the experimental spectrum, while the simple LSDA is successful. Contrary to the expectation, it is found that EuIn2X2 (X = P,As) has a large oscillator strength for the f → d transitions in the low-energy range (below 1.5 eV) in which effects of the joint density of states play a key role. The materials show a sizeable magneto-optical Kerr effect.

Combinatorial computational chemistry approach to the design of metal catalysts for deNOx

International Nuclear Information System (INIS)

Endou, Akira; Jung, Changho; Kusagaya, Tomonori; Kubo, Momoji; Selvam, Parasuraman; Miyamoto, Akira

2004-01-01

Combinatorial chemistry is an efficient technique for the synthesis and screening of a large number of compounds. Recently, we introduced the combinatorial approach to computational chemistry for catalyst design and proposed a new method called ''combinatorial computational chemistry''. In the present study, we have applied this combinatorial computational chemistry approach to the design of precious metal catalysts for deNO x . As the first step of the screening of the metal catalysts, we studied Rh, Pd, Ag, Ir, Pt, and Au clusters regarding the adsorption properties towards NO molecule. It was demonstrated that the energetically most stable adsorption state of NO on Ir model cluster, which was irrespective of both the shape and number of atoms including the model clusters

Ga-Ga bonding and tunnel framework in the new Zintl phase Ba{sub 3}Ga{sub 4}Sb{sub 5}

Energy Technology Data Exchange (ETDEWEB)

Park, S -M; Kim, S -J; Kanatzidis, M G

2003-11-01

A new Zintl phase Ba{sub 3}Ga{sub 4}Sb{sub 5} was obtained from the reaction of Ba and Sb in excess Ga flux at 1000 deg. C, and its structure was determined with single-crystal X-ray diffraction methods. It crystallizes in the orthorhombic space group Pnma (No. 62) with a=13.248(3) A, b=4.5085(9) A, c=24.374(5) A and Z=4. Ba{sub 3}Ga{sub 4}Sb{sub 5} has a three-dimensional [Ga{sub 4}Sb{sub 5}]{sup 6-} framework featuring large tunnels running along the b-axis and accommodating the Ba ions. The structure also has small tube-like tunnels of pentagonal and rhombic cross-sections. The structure contains ethane-like dimeric Sb{sub 3}Ga-GaSb{sub 3} units and GaSb{sub 4} tetrahedra that are connected to form 12- and 14-membered tunnels. Band structure calculations confirm that the material is a semiconductor and indicate that the structure is stabilized by strong Ga-Ga covalent bonding interactions.

Electron-triggered chemistry in HNO3/H2O complexes

Czech Academy of Sciences Publication Activity Database

Lengyel, Jozef; Ončák, M.; Fedor, Juraj; Kočišek, Jaroslav; Pysanenko, Andriy; Beyer, M. K.; Fárník, Michal

2017-01-01

Roč. 19, č. 19 (2017), s. 11753-11758 ISSN 1463-9076 R&D Projects: GA ČR(CZ) GA15-12386S Institutional support: RVO:61388955 Keywords : electron-triggered chemistry * acid-water clusters * gas-phase reactions Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 4.123, year: 2016

Coupled-cluster calculations for ground and excited states of closed- and open-shell nuclei using methods of quantum chemistry

International Nuclear Information System (INIS)

Wloch, Marta; Gour, Jeffrey R; Piecuch, Piotr; Dean, David J; Hjorth-Jensen, Morten; Papenbrock, Thomas

2005-01-01

We discuss large-scale ab initio calculations of ground and excited states of 16 O and preliminary calculations for 15 O and 17 O using coupled-cluster methods and algorithms developed in quantum chemistry. By using realistic two-body interactions and the renormalized form of the Hamiltonian obtained with a no-core G-matrix approach, we are able to obtain the virtually converged results for 16 O and promising results for 15 O and 17 O at the level of two-body interactions. The calculated properties other than binding and excitation energies include charge radius and charge form factor. The relatively low costs of coupled-cluster calculations, which are characterized by the low-order polynomial scaling with the system size, enable us to probe large model spaces with up to seven or eight major oscillator shells, for which nontruncated shell-model calculations for nuclei with A = 15-17 active particles are presently not possible

Electron-triggered chemistry in HNO3/H2O complexes

Czech Academy of Sciences Publication Activity Database

Lengyel, Jozef; Ončák, M.; Fedor, Juraj; Kočišek, Jaroslav; Pysanenko, Andriy; Beyer, M. K.; Fárník, Michal

2017-01-01

Roč. 19, č. 19 (2017), s. 11753-11758 ISSN 1463-9076 R&D Projects: GA ČR(CZ) GA15-12386S Institutional support: RVO:61388955 Keywords : electron-triggered chemistry * acid-water clusters * gas-phase reaction s Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 4.123, year: 2016

STM-electroluminescence from clustered C3N4 nanodomains synthesized via green chemistry process.

Science.gov (United States)

Andrade, E P; Costa, B B A; Chaves, C R; de Paula, A M; Cury, L A; Malachias, A; Safar, G A M

2018-01-01

A Scanning Tunneling Microscopy/Spectroscopy (STM/STS) and synchrotron X-ray diffraction study on clustered C 3 N 4 nanoparticles (nanoflakes) is conducted on green-chemistry synthesized samples obtained from chitosan through high power sonication. Morphological aspects and the electronic characteristics are investigated. The observed bandgap of the nanoflakes reveals the presence of different phases in the material. Combining STM morphology, STS spectra and X-ray diffraction (XRD) results one finds that the most abundant phase is graphitic C 3 N 4 . A high density of defects is inferred from the XRD measurements. Additionally, STM-electroluminescence (STMEL) is detected in C 3 N 4 nanoflakes deposited on a gold substrate. The tunneling current creates photons that are three times more energetic than the tunneling electrons of the STM sample. We ponder about the two most probable models to explain the observed photon emission energy: either a nonlinear optical phenomenon or a localized state emission. Copyright © 2017 Elsevier B.V. All rights reserved.

Site-Specific Biomolecule Labeling with Gold Clusters

OpenAIRE

Ackerson, Christopher J.; Powell, Richard D.; Hainfeld, James F.

2010-01-01

Site-specific labeling of biomolecules in vitro with gold clusters can enhance the information content of electron cryomicroscopy experiments. This chapter provides a practical overview of well-established techniques for forming biomolecule/gold cluster conjugates. Three bioconjugation chemistries are covered: Linker-mediated bioconjugation, direct gold–biomolecule bonding, and coordination-mediated bonding of nickel(II) nitrilotriacetic acid (NTA)-derivatized gold clusters to polyhistidine (...

Similarities and Differences Between Atomic Nuclei and Clusters: Toward a Unified Development of Cluster Science. Proceedings

International Nuclear Information System (INIS)

Abe, Y.; Arai, I.; Lee, S.; Yabana, K.

1998-01-01

These proceedings represent papers presented at the symposium on Similarities and Differences Between Atomic Nuclei and Clusters held in Tsukuba, Japan in July, 1997. A wide range of topics were covered including the quantum and thermal properties of free clusters to high energy impacts of clusters on solid surfaces. Fullerenes and carbon clusters chemistry was discussed in some detail. This symposium brought together scientists from many disciplines: nuclear and solid state physicists, chemists, and material scientists. There are 62 papers in the proceedings and 3 have been abstracted for the Energy Science and Technology database

Site-Specific Biomolecule Labeling with Gold Clusters

Science.gov (United States)

Ackerson, Christopher J.; Powell, Richard D.; Hainfeld, James F.

2013-01-01

Site-specific labeling of biomolecules in vitro with gold clusters can enhance the information content of electron cryomicroscopy experiments. This chapter provides a practical overview of well-established techniques for forming biomolecule/gold cluster conjugates. Three bioconjugation chemistries are covered: Linker-mediated bioconjugation, direct gold–biomolecule bonding, and coordination-mediated bonding of nickel(II) nitrilotriacetic acid (NTA)-derivatized gold clusters to polyhistidine (His)-tagged proteins. PMID:20887859

A New Approach to the General Chemistry Laboratory

Science.gov (United States)

Bieron, Joseph F.; McCarthy, Paul J.; Kermis, Thomas W.

1996-11-01

Background Canisius College is a medium-sized liberal arts college with a longstanding tradition of maintaining an excellent chemistry program. We realized a few years ago, however, that this tradition was not being sustained by our General Chemistry laboratory course, which had not changed significantly in years. With the help of a grant from the National Science Foundation, our department has been able to design a new laboratory course built around several guiding principles. The design called for experiments to be grouped in units or clusters. Each cluster has a unifying theme or common thread, which gives some coherence to the experiments. The clusters and experiments are listed in the appendix and briefly explained below. Course Design Cluster A's topic is organic and polymer chemistry, and its main objective is to show that chemistry can be enjoyable and relevant to common experiences. Data collection is minimal and hands-on manipulation with observable products is emphasized. Cluster B is a case study of the chemistry of maintaining a swimming pool. The common theme is solution chemistry, and the experiments are designed to promote critical thinking. Cluster C encompasses both oxidation - reduction reactions and electrochemistry, and attempts to show the commonality of these important topics. Cluster D is a series of experiments on methods and techniques of analytical chemistry; in this group the analysis of unknown materials is undertaken. Cluster E is covered last in the second semester, and it stresses important concepts in chemistry at a slightly more advanced level. The emphasis is on the relationship of experiment to theory, and the cluster involves experiments in kinetics, equilibrium, and synthesis. Other guidelines that we considered important in our design were the use of computers (when appropriate), the introduction of microscale chemistry, and the use of instrumentation whenever possible. A separate cluster, labeled Mac, was developed to provide

Proceedings of the DAE-BRNS fifth interdisciplinary symposium on materials chemistry

International Nuclear Information System (INIS)

Jafar, Mohsin; Tyagi, Adish; Tyagi, Deepak

2014-12-01

The focus of the present symposium on materials chemistry was on research areas in materials chemistry like: nuclear materials; high purity materials; nanomaterials and clusters; carbon based materials; fuel cell materials and other electro-ceramics; biomaterials; polymers and soft condensed matter; materials for energy conversion; thin films and surface chemistry; magnetic materials; catalysis; chemical sensors; organic and organometallic compounds; computational material chemistry etc. Papers relevant to INIS are indexed separately

Polyhedral boron-containing cluster chemistry: Aspects of architecture beyond the icosahedron

Czech Academy of Sciences Publication Activity Database

Shea, S. L.; Bould, J.; Londesborough, M. G. S.; Perea, S. D.; Franken, A.; Ormsby, D. L.; Jelínek, Tomáš; Štíbr, Bohumil; Holub, Josef; Kilner, C. A.; Thorton-Pett, M.; Kennedy, J. D.

2003-01-01

Roč. 75, č. 9 (2003), s. 1239-1248 ISSN 0033-4545 R&D Projects: GA MŠk LN00A028 Grant - others:UK EPRC(GB) J56929 Institutional research plan: CEZ:AV0Z4032918 Keywords : molecular chemistry * carbon hydrides Subject RIV: CA - Inorganic Chemistry Impact factor: 1.471, year: 2003

Between Localization and Delocalization: Ru(cod)2+ Units in the Zintl Clusters [Bi9 {Ru(cod)}2 ]3- and [Tl2 Bi6 {Ru(cod)}]2.

Science.gov (United States)

Lichtenberger, Niels; Spang, Nils; Eichhöfer, Andreas; Dehnen, Stefanie

2017-10-16

Reactions of [K(crypt-222)] 2 (TlBi 3 )⋅0.5 en (1 b) with [Ru(cod)(H 2 CC(Me)CH 2 ) 2 ] (A) in 1,2-diaminoethane (en) led to the formation of two compounds with new bismuth-rich cluster anions, [K(crypt-222)] 3 [Bi 9 {Ru(cod)} 2 ]⋅1.5 en (2) and [K(crypt-222)] 2 [Tl 2 Bi 6 {Ru(cod)}]⋅2 tol (3), alongside the salt of a binary nido cluster, [K(crypt-222)] 3 (Tl 4 Bi 5 )⋅2 en (4). The anions in 2 and 3 are two further examples of rare heterometallic clusters containing Ru atoms. As one cod ligand is retained on each Ru atom in both clusters, the anions may be viewed as intermediates on the way towards larger, ligand-free intermetalloid clusters. Quantum-chemical studies provided insight into the bonding situation in these clusters. According to these studies, the anion of 2 features both electron-precise and electron-deficient parts. Electrospray ionization mass spectrometry analysis indicated that the clusters undergo stepwise fragmentation. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigation of glutathione-derived electrostatic and hydrogen-bonding interactions and their role in defining Grx5 [2Fe-2S] cluster optical spectra and transfer chemistry.

Science.gov (United States)

Sen, Sambuddha; Bonfio, Claudia; Mansy, Sheref S; Cowan, J A

2018-03-01

Human glutaredoxin 5 (Grx5) is one of the core components of the Isc (iron-sulfur cluster) assembly and trafficking machinery, and serves as an intermediary cluster carrier, putatively delivering cluster from the Isu scaffold protein to target proteins. The tripeptide glutathione is intimately involved in this role, providing cysteinyl coordination to the iron center of the Grx5-bound [2Fe-2S] cluster. Grx5 has a well-defined glutathione-binding pocket with protein amino acid residues providing many ionic and hydrogen binding contacts to the bound glutathione. In this report, we investigated the importance of these interactions in cluster chirality and exchange reactivity by systematically perturbing the crucial contacts by use of natural and non-natural amino acid substitutions to disrupt the binding contacts from both the protein and glutathione. Native Grx5 could be reconstituted with all of the glutathione analogs used, as well as other thiol ligands, such as DTT or L-cysteine, by in vitro chemical reconstitution, and the holo proteins were found to transfer [2Fe-2S] cluster to apo ferredoxin 1 at comparable rates. However, the circular dichroism spectra of these derivatives displayed prominent differences that reflect perturbations in local cluster chirality. These studies provided a detailed molecular understanding of glutathione-protein interactions in holo Grx5 that define both cluster spectroscopy and exchange chemistry.

Structural, elastic, electronic, optical and thermoelectric properties of the Zintl-phase Ae3AlAs3 (Ae = Sr, Ba)

Science.gov (United States)

Benahmed, A.; Bouhemadou, A.; Alqarni, B.; Guechi, N.; Al-Douri, Y.; Khenata, R.; Bin-Omran, S.

2018-05-01

First-principles calculations were performed to investigate the structural, elastic, electronic, optical and thermoelectric properties of the Zintl-phase Ae3AlAs3 (Ae = Sr, Ba) using two complementary approaches based on density functional theory. The pseudopotential plane-wave method was used to explore the structural and elastic properties whereas the full-potential linearised augmented plane wave approach was used to study the structural, electronic, optical and thermoelectric properties. The calculated structural parameters are in good consistency with the corresponding measured ones. The single-crystal and polycrystalline elastic constants and related properties were examined in details. The electronic properties, including energy band dispersions, density of states and charge-carrier effective masses, were computed using Tran-Blaha modified Becke-Johnson functional for the exchange-correlation potential. It is found that both studied compounds are direct band gap semiconductors. Frequency-dependence of the linear optical functions were predicted for a wide photon energy range up to 15 eV. Charge carrier concentration and temperature dependences of the basic parameters of the thermoelectric properties were explored using the semi-classical Boltzmann transport model. Our calculations unveil that the studied compounds are characterised by a high thermopower for both carriers, especially the p-type conduction is more favourable.

Quantum chemistry of the minimal CdSe clusters

Science.gov (United States)

Yang, Ping; Tretiak, Sergei; Masunov, Artëm E.; Ivanov, Sergei

2008-08-01

Colloidal quantum dots are semiconductor nanocrystals (NCs) which have stimulated a great deal of research and have attracted technical interest in recent years due to their chemical stability and the tunability of photophysical properties. While internal structure of large quantum dots is similar to bulk, their surface structure and passivating role of capping ligands (surfactants) are not fully understood to date. We apply ab initio wavefunction methods, density functional theory, and semiempirical approaches to study the passivation effects of substituted phosphine and amine ligands on the minimal cluster Cd2Se2, which is also used to benchmark different computational methods versus high level ab initio techniques. Full geometry optimization of Cd2Se2 at different theory levels and ligand coverage is used to understand the affinities of various ligands and the impact of ligands on cluster structure. Most possible bonding patterns between ligands and surface Cd/Se atoms are considered, including a ligand coordinated to Se atoms. The degree of passivation of Cd and Se atoms (one or two ligands attached to one atom) is also studied. The results suggest that B3LYP/LANL2DZ level of theory is appropriate for the system modeling, whereas frequently used semiempirical methods (such as AM1 and PM3) produce unphysical results. The use of hydrogen atom for modeling of the cluster passivating ligands is found to yield unphysical results as well. Hence, the surface termination of II-VI semiconductor NCs with hydrogen atoms often used in computational models should probably be avoided. Basis set superposition error, zero-point energy, and thermal corrections, as well as solvent effects simulated with polarized continuum model are found to produce minor variations on the ligand binding energies. The effects of Cd-Se complex structure on both the electronic band gap (highest occupied molecular orbital-lowest unoccupied molecular orbital energy difference) and ligand binding

Recent development in clusters of rare earths and actinides. Chemistry and materials

Energy Technology Data Exchange (ETDEWEB)

Zheng, Zhiping (ed.) [Arizona Univ., Tucson, AZ (United States). Dept. of Chemistry and Biochemistry

2017-02-01

This book contains the following eight contributions: 1. Lanthanide Hydroxide Cluster Complexes via Ligand-Controlled Hydrolysis of the Lanthanide Ions (Zhonghao Zhang, Yanan Zhang, and Zhiping Zheng); 2. Synthesis and Structures of Lanthanide-Transition Metal Clusters (Xiu-Ying Zheng, Xiang-Jian Kong, and La-Sheng Long); 3. Hydrothermal Synthesis of Lanthanide and Lanthanide-Transition-Metal Cluster Organic Frameworks via Synergistic Coordination Strategy (Jian-Wen Cheng and Guo-Yu Yang); 4. Oxo Clusters of 5f Elements (Sarah Hickam and Peter C.); 5. Construction and Luminescence Properties of 4f and d-4f Clusters with Salen-Type Schiff Base Ligands (Xiaoping Yang, Shiqing Wang, Chengri Wang, Shaoming Huang, and Richard A.); 6. 4f-Clusters for Cryogenic Magnetic Cooling (Yan-Cong Chen, Jun-Liang Liu, and Ming-Liang Tong); 7. Lanthanide Clusters Toward Single-Molecule Magnets (Tian Han, You-Song Ding, and Yan-Zhen Zheng); 8. Molecular Rare Earth Hydride Clusters (Takanori Shima and Zhaomin Hou).

Recent development in clusters of rare earths and actinides. Chemistry and materials

International Nuclear Information System (INIS)

Zheng, Zhiping

2017-01-01

This book contains the following eight contributions: 1. Lanthanide Hydroxide Cluster Complexes via Ligand-Controlled Hydrolysis of the Lanthanide Ions (Zhonghao Zhang, Yanan Zhang, and Zhiping Zheng); 2. Synthesis and Structures of Lanthanide-Transition Metal Clusters (Xiu-Ying Zheng, Xiang-Jian Kong, and La-Sheng Long); 3. Hydrothermal Synthesis of Lanthanide and Lanthanide-Transition-Metal Cluster Organic Frameworks via Synergistic Coordination Strategy (Jian-Wen Cheng and Guo-Yu Yang); 4. Oxo Clusters of 5f Elements (Sarah Hickam and Peter C.); 5. Construction and Luminescence Properties of 4f and d-4f Clusters with Salen-Type Schiff Base Ligands (Xiaoping Yang, Shiqing Wang, Chengri Wang, Shaoming Huang, and Richard A.); 6. 4f-Clusters for Cryogenic Magnetic Cooling (Yan-Cong Chen, Jun-Liang Liu, and Ming-Liang Tong); 7. Lanthanide Clusters Toward Single-Molecule Magnets (Tian Han, You-Song Ding, and Yan-Zhen Zheng); 8. Molecular Rare Earth Hydride Clusters (Takanori Shima and Zhaomin Hou).

Surveys of research in the Chemistry Division, Argonne National Laboratory

Energy Technology Data Exchange (ETDEWEB)

Grazis, B.M. [ed.

1992-11-01

Research reports are presented on reactive intermediates in condensed phase (radiation chemistry, photochemistry), electron transfer and energy conversion, photosynthesis and solar energy conversion, metal cluster chemistry, chemical dynamics in gas phase, photoionization-photoelectrons, characterization and reactivity of coal and coal macerals, premium coal sample program, chemical separations, heavy elements coordination chemistry, heavy elements photophysics/photochemistry, f-electron interactions, radiation chemistry of high-level wastes (gas generation in waste tanks), ultrafast molecular electronic devices, and nuclear medicine. Separate abstracts have been prepared. Accelerator activites and computer system/network services are also reported.

Surveys of research in the Chemistry Division, Argonne National Laboratory

Energy Technology Data Exchange (ETDEWEB)

Grazis, B.M. (ed.)

1992-01-01

Research reports are presented on reactive intermediates in condensed phase (radiation chemistry, photochemistry), electron transfer and energy conversion, photosynthesis and solar energy conversion, metal cluster chemistry, chemical dynamics in gas phase, photoionization-photoelectrons, characterization and reactivity of coal and coal macerals, premium coal sample program, chemical separations, heavy elements coordination chemistry, heavy elements photophysics/photochemistry, f-electron interactions, radiation chemistry of high-level wastes (gas generation in waste tanks), ultrafast molecular electronic devices, and nuclear medicine. Separate abstracts have been prepared. Accelerator activites and computer system/network services are also reported.

Computational Design of Clusters for Catalysis

Science.gov (United States)

Jimenez-Izal, Elisa; Alexandrova, Anastassia N.

2018-04-01

When small clusters are studied in chemical physics or physical chemistry, one perhaps thinks of the fundamental aspects of cluster electronic structure, or precision spectroscopy in ultracold molecular beams. However, small clusters are also of interest in catalysis, where the cold ground state or an isolated cluster may not even be the right starting point. Instead, the big question is: What happens to cluster-based catalysts under real conditions of catalysis, such as high temperature and coverage with reagents? Myriads of metastable cluster states become accessible, the entire system is dynamic, and catalysis may be driven by rare sites present only under those conditions. Activity, selectivity, and stability are highly dependent on size, composition, shape, support, and environment. To probe and master cluster catalysis, sophisticated tools are being developed for precision synthesis, operando measurements, and multiscale modeling. This review intends to tell the messy story of clusters in catalysis.

Mo{sub 2}B{sub 4}O{sub 9} - connecting borate and metal-cluster chemistry

Energy Technology Data Exchange (ETDEWEB)

Schmitt, Martin K.; Huppertz, Hubert [Institut fuer Allgemeine, Anorganische und Theoretische Chemie, Universitaet Innsbruck (Austria); Janka, Oliver; Poettgen, Rainer [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster (Germany); Benndorf, Christopher [Institut fuer Anorganische und Analytische Chemie, Universitaet Muenster (Germany); Institut fuer Physikalische Chemie, Universitaet Muenster (Germany); Institut fuer Mineralogie, Kristallographie und Materialwissenschaften, Universitaet Leipzig (Germany); Oliveira, Marcos de Jr. [Sao Carlos Institute of Physics, University of Sao Paulo, Sao Carlos (Brazil); Eckert, Hellmut [Institut fuer Physikalische Chemie, Universitaet Muenster (Germany); Sao Carlos Institute of Physics, University of Sao Paulo, Sao Carlos (Brazil); Pielnhofer, Florian; Tragl, Amadeus-Samuel [Institut fuer Anorganische Chemie, Universitaet Regensburg (Germany); Weihrich, Richard [Institut fuer Materials Resource Management, Universitaet Augsburg (Germany); Joachim, Bastian [Institut fuer Mineralogie und Petrographie, Universitaet Innsbruck (Austria); Johrendt, Dirk [Department Chemie, Ludwig-Maximilians-Universitaet Muenchen (Germany)

2017-06-01

We report on the first thoroughly characterized molybdenum borate, which was synthesized in a high-pressure/high-temperature experiment at 12.3 GPa/1300 C using a Walker-type multianvil apparatus. Mo{sub 2}B{sub 4}O{sub 9} incorporates tetrahedral molybdenum clusters into an anionic borate crystal structure - a structural motif that has never been observed before in the wide field of borate crystal chemistry. The six bonding molecular orbitals of the [Mo{sub 4}] tetrahedron are completely filled with 12 electrons, which are fully delocalized over the four molybdenum atoms. This finding is in agreement with the results of the magnetic measurements, which confirmed the diamagnetic character of Mo{sub 2}B{sub 4}O{sub 9}. The two four-coordinated boron sites can be differentiated in the {sup 11}B MAS-NMR spectrum because of the strongly different degrees of local distortions. Experimentally obtained IR and Raman bands were assigned to vibrational modes based on DFT calculations. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

Towards a unified developments of cluster science

International Nuclear Information System (INIS)

Wang Guanghou

1998-01-01

In the development of cluster science many concepts and methods have been introduced from nuclear physics, condensed matter physics and quantum chemistry, forming an interdisciplinary field between atomic and molecular physics on the one hand and condensed matter physics on the other hand. Recent achievements in the study of the structures and properties of clusters are reviewed in comparison with those of nuclei and quantum dots

CO chemistry/research trends in CO chemistry in the US

Energy Technology Data Exchange (ETDEWEB)

Cantacuzene, M

1978-10-01

Research trends in CO chemistry in the U.S. include the development of stable and selective homogeneous catalysts which would facilitate the removal of the heat of reaction and be resistant to sulfur poisoning for the methanation reaction, methanol synthesis, and Fischer-Tropsch synthesis; development of low-temperature homogeneous water gas shift catalysts; and research on the coordination chemistry and photochemical conversions of CO/sub 2/. In 1977, the National Science Foundation awarded 16 contracts for a total of $720,000 to promote the research in this field, including studies on chemisorption and heterogeneous catalysis (four contracts) and on transition metal complexes (ten contracts, of which seven are dedicated to metal clusters). Carbon monoxide-based processes, including water gas shift reactions, CO reduction to alkanes and alcohols, hydroformylation, and homogeneous carbonylation processes, recently developed in the U.S. are listed.

Expanding Comparative Literature into Comparative Sciences Clusters with Neutrosophy and Quad-stage Method

Directory of Open Access Journals (Sweden)

Fu Yuhua

2016-08-01

Full Text Available By using Neutrosophy and Quad-stage Method, the expansions of comparative literature include: comparative social sciences clusters, comparative natural sciences clusters, comparative interdisciplinary sciences clusters, and so on. Among them, comparative social sciences clusters include: comparative literature, comparative history, comparative philosophy, and so on; comparative natural sciences clusters include: comparative mathematics, comparative physics, comparative chemistry, comparative medicine, comparative biology, and so on.

Ion-molecule reactions: their role in radiation chemistry

International Nuclear Information System (INIS)

Lias, S.G.; Ausloos, P.

1975-01-01

A comprehensive review of ion--molecule reactions is presented, including information from mass spectrometric, organic chemistry, and NMR studies, from theoretical calculations, and from gas and liquid phase radiation chemistry. Special emphasis is placed on interpreting the role of ion--molecule reactions in systems under high energy irradiation. The discussion is presented under the following chapter headings: ion--molecule reactions and their role in radiation chemistry; unimolecular processes: the nature and structure of ionic intermediates in radiolysis; ion lifetimes and the fate of unreactive ions; kinetics and mechanisms of ion--molecule reactions; proton transfer reactions; negative atom and two-atom transfer reactions; condensation reactions; and, association or clustering reactions

A facility for using cluster research to study environmental problems

International Nuclear Information System (INIS)

1991-11-01

This report begins by describing the general application of cluster based research to environmental chemistry and the development of a Cluster Structure and Dynamics Research Facility (CSDRF). Next, four important areas of cluster research are described in more detail, including how they can impact environmental problems. These are: surface-supported clusters, water and contaminant interactions, time-resolved dynamic studies in clusters, and cluster structures and reactions. These facilities and equipment required for each area of research are then presented. The appendices contain workshop agenda and a listing of the researchers who participated in the workshop discussions that led to this report

A facility for using cluster research to study environmental problems

Energy Technology Data Exchange (ETDEWEB)

1991-11-01

This report begins by describing the general application of cluster based research to environmental chemistry and the development of a Cluster Structure and Dynamics Research Facility (CSDRF). Next, four important areas of cluster research are described in more detail, including how they can impact environmental problems. These are: surface-supported clusters, water and contaminant interactions, time-resolved dynamic studies in clusters, and cluster structures and reactions. These facilities and equipment required for each area of research are then presented. The appendices contain workshop agenda and a listing of the researchers who participated in the workshop discussions that led to this report.

Proceedings of DAE-BRNS third international symposium on materials chemistry

International Nuclear Information System (INIS)

Tyagi, Deepak; Banerjee, Atindra Mohan; Nigam, Sandeep; Varma, Salil; Tripathi, Arvind Kumar; Bharadwaj, Shyamala Rajkumar; Das, Dasarathi

2010-12-01

The present volume consists of the proceedings of the DAE-BRNS Third International Symposium on Materials Chemistry. In order to keep pace with the advancements made in the area of materials chemistry, new topics like materials for energy conversion, biomaterials, carbon based materials, soft condensed materials, thin films, surface chemistry, polymer based materials, organic and organometallics, magnetic materials and high purity materials have been included in this symposium while topics like nuclear materials, nanomaterials and clusters, catalysis, chemical sensors, fuel cell materials and computational research in materials chemistry have been continued as important features of the symposium. Papers relevant to INIS are indexed separately

THREE DISCRETE GROUPS WITH HOMOGENEOUS CHEMISTRY ALONG THE RED GIANT BRANCH IN THE GLOBULAR CLUSTER NGC 2808

International Nuclear Information System (INIS)

Carretta, E.

2014-01-01

We present the homogeneous reanalysis of Mg and Al abundances from high resolution UVES/FLAMES spectra for 31 red giants in the globular cluster NGC 2808. We found a well defined Mg-Al anticorrelation reaching a regime of subsolar Mg abundance ratios, with a spread of about 1.4 dex in [Al/Fe]. The main result from the improved statistics of our sample is that the distribution of stars is not continuous along the anticorrelation because they are neatly clustered into three distinct clumps, each with different chemical compositions. One group (P) shows a primordial composition of field stars of similar metallicity, and the other two (I and E) have increasing abundances of Al and decreasing abundances of Mg. The fraction of stars we found in the three components (P: 68%, I: 19%, E: 13%) is in excellent agreement with the ratios computed for the three distinct main sequences in NGC 2808: for the first time there is a clear correspondence between discrete photometric sequences of dwarfs and distinct groups of giants with homogeneous chemistry. The composition of the I group cannot be reproduced by mixing of matter with extreme processing in hot H-burning and gas with pristine, unprocessed composition, as also found in the recent analysis of three discrete groups in NGC 6752. This finding suggests that different classes of polluters were probably at work in NGC 2808 as well

Modelling of Krn+ Clusters. II. Photoabsorption Spectra of Small Clusters (n=2 - 5)

Czech Academy of Sciences Publication Activity Database

Kalus, R.; Paidarová, Ivana; Hrivňák, D.; Gadea, F. X.

2004-01-01

Roč. 298, 1/3 (2004), s. 155-166 ISSN 0301-0104 R&D Projects: GA ČR GA203/02/1204 Grant - others:Barrande Program(XE) 2003-024-1 Institutional research plan: CEZ:AV0Z4040901 Keywords : krypton * rare gases * cluster ions Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.316, year: 2004

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

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.

Analysis of mixed nitric oxide - Water clusters by complementary ionization methods

Czech Academy of Sciences Publication Activity Database

Šmídová, Daniela; Lengyel, Jozef; Kočišek, Jaroslav; Pysanenko, Andriy; Fárník, Michal

2017-01-01

Roč. 421, OCT 2017 (2017), s. 144-149 ISSN 1387-3806 R&D Projects: GA ČR(CZ) GA17-04068S Institutional support: RVO:61388955 Keywords : Cluster mass spectrometry * Atmospheric aerosols * Electron attachment Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 1.702, year: 2016

Argonne National Lab gets Linux network teraflop cluster

CERN Multimedia

2003-01-01

"Linux NetworX, Salt Lake City, Utah, has delivered an Evolocity II (E2) Linux cluster to Argonne National Laboratory that is capable of performing more than one trillion calculations per second (1 teraFLOP). The cluster, named "Jazz" by Argonne, is designed to provide optimum performance for multiple disciplines such as chemistry, physics and reactor engineering and will be used by the entire scientific community at the Lab" (1 page).

Proceedings of the DAE-BRNS fourth interdisciplinary symposium on materials chemistry

International Nuclear Information System (INIS)

Tyagi, D.; Banerjee, A.M.; Bhattacharyya, K.; Nigam, S.; Varma, S.; Tripathi, A.K.; Das, D.

2012-12-01

This symposium covers almost all the contemporary research areas of materials chemistry like materials for energy conversion, biomaterials, carbon based materials, chemical sensors, fuel cell materials and other electro-ceramics, polymers and soft condensed matters, thin films and surface chemistry, organic and organometallics, high purity materials, nanomaterials and clusters to acquaint ourselves with the advancement made in these emerging areas. Topics like nuclear materials, magnetic materials, catalysis and computational materials chemistry continue to be important facet of ISMC series of symposia. Papers relevant to INIS are indexed separately

Anomalous properties of technetium clusters

International Nuclear Information System (INIS)

Kryuchkov, S.V.

1985-01-01

On the basis of critical evaluation of literature data in the field of chemistry of technetium cluster compounds with ligands of a weak field a conclusion is made on specific, ''anomalous'' properties of technetium cluster complexes which consist in an increased ability of the given element to the formation of a series of binuclear and multinuclear clusters, similar in composition and structure and easily transforming in each other. The majority of technetium clusters unlike similar compounds of other elements are paramagnetic with one unpaired electron on ''metallic'' MO of loosening type. All theoretical conceptions known today on the electronic structure of technetium clusters are considered. It is pointed out, that the best results in the explanation of ''anomalous'' properties of technetium clusters can be obtained in the framework of nonempirical methods of self-consistent field taking into account configuration interactions. It is also shown, that certain properties of technetium clusters can be explained on the basis of qualitative model of Coulomb repulsion of metal atoms in clusters. The conclusion is made, that technetium position in the Periodic table, as well as recently detected technetium property to the decrease of effective charge on its atoms during M-M bond formation promote a high ability of the element to cluster formation both with weak field ligands and with strong field one

Cluster ions and van der Waals molecules

CERN Document Server

Smirnov, Boris M

1992-01-01

This review discusses current ideas in the physics and chemistry of cluster ions and Van der Waals molecules as well as presenting numerical data on their parameters and the processes involving them. It is also a detailed reference on basic data relating to many species.

Designing a Scalable Fault Tolerance Model for High Performance Computational Chemistry: A Case Study with Coupled Cluster Perturbative Triples.

Science.gov (United States)

van Dam, Hubertus J J; Vishnu, Abhinav; de Jong, Wibe A

2011-01-11

In the past couple of decades, the massive computational power provided by the most modern supercomputers has resulted in simulation of higher-order computational chemistry methods, previously considered intractable. As the system sizes continue to increase, the computational chemistry domain continues to escalate this trend using parallel computing with programming models such as Message Passing Interface (MPI) and Partitioned Global Address Space (PGAS) programming models such as Global Arrays. The ever increasing scale of these supercomputers comes at a cost of reduced Mean Time Between Failures (MTBF), currently on the order of days and projected to be on the order of hours for upcoming extreme scale systems. While traditional disk-based check pointing methods are ubiquitous for storing intermediate solutions, they suffer from high overhead of writing and recovering from checkpoints. In practice, checkpointing itself often brings the system down. Clearly, methods beyond checkpointing are imperative to handling the aggravating issue of reducing MTBF. In this paper, we address this challenge by designing and implementing an efficient fault tolerant version of the Coupled Cluster (CC) method with NWChem, using in-memory data redundancy. We present the challenges associated with our design, including an efficient data storage model, maintenance of at least one consistent data copy, and the recovery process. Our performance evaluation without faults shows that the current design exhibits a small overhead. In the presence of a simulated fault, the proposed design incurs negligible overhead in comparison to the state of the art implementation without faults.

A facility for using cluster research to study environmental problems. Workshop proceedings

Energy Technology Data Exchange (ETDEWEB)

1991-11-01

This report begins by describing the general application of cluster based research to environmental chemistry and the development of a Cluster Structure and Dynamics Research Facility (CSDRF). Next, four important areas of cluster research are described in more detail, including how they can impact environmental problems. These are: surface-supported clusters, water and contaminant interactions, time-resolved dynamic studies in clusters, and cluster structures and reactions. These facilities and equipment required for each area of research are then presented. The appendices contain workshop agenda and a listing of the researchers who participated in the workshop discussions that led to this report.

Application of cluster computing in materials science

International Nuclear Information System (INIS)

Kuzmin, A.

2006-01-01

Solution of many problems in materials science requires that high performance computing (HPC) be used. Therefore, a cluster computer, Latvian Super-cluster (LASC), was constructed at the Institute of Solid State Physics of the University of Latvia in 2002. The LASC is used for advanced research in the fields of quantum chemistry, solid state physics and nano materials. In this work we overview currently available computational technologies and exemplify their application by interpretation of x-ray absorption spectra for nano-sized ZnO. (author)

Optical properties of DNA-hosted silver clusters

NARCIS (Netherlands)

Markešević, Nemanja

2015-01-01

DNA-hosted silver clusters (Ag:DNAs) have attracted a lot of attention due to their small size (~20 atoms), wide range of applications in chemistry and biology, and sequence-dependent optical tunability. Most of the previous studies are focused on the ensemble of emitters in solution. However,

Cluster-based analysis of multi-model climate ensembles

Science.gov (United States)

Hyde, Richard; Hossaini, Ryan; Leeson, Amber A.

2018-06-01

Clustering - the automated grouping of similar data - can provide powerful and unique insight into large and complex data sets, in a fast and computationally efficient manner. While clustering has been used in a variety of fields (from medical image processing to economics), its application within atmospheric science has been fairly limited to date, and the potential benefits of the application of advanced clustering techniques to climate data (both model output and observations) has yet to be fully realised. In this paper, we explore the specific application of clustering to a multi-model climate ensemble. We hypothesise that clustering techniques can provide (a) a flexible, data-driven method of testing model-observation agreement and (b) a mechanism with which to identify model development priorities. We focus our analysis on chemistry-climate model (CCM) output of tropospheric ozone - an important greenhouse gas - from the recent Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP). Tropospheric column ozone from the ACCMIP ensemble was clustered using the Data Density based Clustering (DDC) algorithm. We find that a multi-model mean (MMM) calculated using members of the most-populous cluster identified at each location offers a reduction of up to ˜ 20 % in the global absolute mean bias between the MMM and an observed satellite-based tropospheric ozone climatology, with respect to a simple, all-model MMM. On a spatial basis, the bias is reduced at ˜ 62 % of all locations, with the largest bias reductions occurring in the Northern Hemisphere - where ozone concentrations are relatively large. However, the bias is unchanged at 9 % of all locations and increases at 29 %, particularly in the Southern Hemisphere. The latter demonstrates that although cluster-based subsampling acts to remove outlier model data, such data may in fact be closer to observed values in some locations. We further demonstrate that clustering can provide a viable and

Redox Chemisty of Tantalum Clusters on Silica Characterized by X-ray Absorption Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Nemana,S.; Gates, B.

2006-01-01

SiO{sub 2}-supported clusters of tantalum were synthesized from adsorbed Ta(CH{sub 2}Ph){sub 5} by treatment in H{sub 2} at 523 K. The surface species were characterized by X-ray absorption spectroscopy (extended X-ray absorption fine structure (EXAFS) spectroscopy and X-ray absorption near edge spectroscopy (XANES)) and ultraviolet-visible spectroscopy. The EXAFS data show that SiOO{sub 2}-supported tantalum clusters were characterized by a Ta-Ta coordination number of approximately 2, consistent with the presence of tritantalum clusters, on average. When these were reduced in H{sub 2} and reoxidized in O{sub 2}, the cluster nuclearity remained essentially unchanged, although reduction and oxidation occurred, respectively, as shown by XANES and UV-vis spectra; in the reoxidation, the tantalum oxidation state change was approximately two electronic charges per tritantalum cluster. The data demonstrate an analogy between the chemistry of group 5 metals on the SiO{sub 2} support and their chemistry in solution, as determined by the group of Cotton.

Electron attachment and electron ionization of acetic acid clusters embedded in helium nanodroplets

NARCIS (Netherlands)

da Silva, F. Ferreira; Jaksch, S.; Martins, G.; Dang, H. M.; Dampc, M.; Denifl, S.; Maerk, T. D.; Limao-Vieira, P.; Liu, J.; Yang, S.; Ellis, A. M.; Scheier, P.

2009-01-01

The effect of incident electrons on acetic acid clusters is explored for the first time. The acetic acid clusters are formed inside liquid helium nanodroplets and both cationic and anionic products ejected into the gas phase are detected by mass spectrometry. The cation chemistry (induced by

Understanding Boron through Size-Selected Clusters: Structure, Chemical Bonding, and Fluxionality

Energy Technology Data Exchange (ETDEWEB)

Sergeeva, Alina P.; Popov, Ivan A.; Piazza, Zachary A.; Li, Wei-Li; Romanescu, Constantin; Wang, Lai S.; Boldyrev, Alexander I.

2014-04-15

Conspectus Boron is an interesting element with unusual polymorphism. While three-dimensional (3D) structural motifs are prevalent in bulk boron, atomic boron clusters are found to have planar or quasi-planar structures, stabilized by localized two-center–two-electron (2c–2e) σ bonds on the periphery and delocalized multicenter–two-electron (nc–2e) bonds in both σ and π frameworks. Electron delocalization is a result of boron’s electron deficiency and leads to fluxional behavior, which has been observed in B13+ and B19–. A unique capability of the in-plane rotation of the inner atoms against the periphery of the cluster in a chosen direction by employing circularly polarized infrared radiation has been suggested. Such fluxional behaviors in boron clusters are interesting and have been proposed as molecular Wankel motors. The concepts of aromaticity and antiaromaticity have been extended beyond organic chemistry to planar boron clusters. The validity of these concepts in understanding the electronic structures of boron clusters is evident in the striking similarities of the π-systems of planar boron clusters to those of polycyclic aromatic hydrocarbons, such as benzene, naphthalene, coronene, anthracene, or phenanthrene. Chemical bonding models developed for boron clusters not only allowed the rationalization of the stability of boron clusters but also lead to the design of novel metal-centered boron wheels with a record-setting planar coordination number of 10. The unprecedented highly coordinated borometallic molecular wheels provide insights into the interactions between transition metals and boron and expand the frontier of boron chemistry. Another interesting feature discovered through cluster studies is boron transmutation. Even though it is well-known that B–, formed by adding one electron to boron, is isoelectronic to carbon, cluster studies have considerably expanded the possibilities of new structures and new materials using the B�

Chemistry That Applies. What Works Clearinghouse Intervention Report

Science.gov (United States)

What Works Clearinghouse, 2012

2012-01-01

"Chemistry That Applies" is an instructional unit designed to help students in grades 8-10 understand the law of conservation of matter. It consists of 24 lessons organized in four clusters. Working in groups, students explore four chemical reactions: burning, rusting, the decomposition of water, and the reaction of baking soda and…

Molecular Dynamics Studies of Thermal Induced Chemistry in Tatb

Science.gov (United States)

Quenneville, J.; Germann, T. C.; Thompson, A. P.; Kober, E. M.

2007-12-01

A reactive force field (ReaxFF) is used with molecular dynamics to probe the chemistry induced by intense heating (`accelerated cook-off') of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB). Large-system simulations are desired for TATB because of the high degree of carbon clustering expected in this material. Using small, 32-molecule simulations, we calculate the reaction rate as a function of temperature and compare the Arrhenius-predicted activation energy with experiment. Decomposition product evolution (mainly N2, H2O, CO2 and graphitic carbon clusters) is followed using a 576-molecule larger simulation, which also illustrates the effect of system size on both carbon clustering and reaction rate.

Hydration of a Large Anionic Charge Distribution - Naphthalene-Water Cluster Anions

Science.gov (United States)

Weber, J. Mathias; Adams, Christopher L.

2010-06-01

We report the infrared spectra of anionic clusters of naphthalene with up to three water molecules. Comparison of the experimental infrared spectra with theoretically predicted spectra from quantum chemistry calculations allow conclusions regarding the structures of the clusters under study. The first water molecule forms two hydrogen bonds with the π electron system of the naphthalene moiety. Subsequent water ligands interact with both the naphthalene and the other water ligands to form hydrogen bonded networks, similar to other hydrated anion clusters. Naphthalene-water anion clusters illustrate how water interacts with negative charge delocalized over a large π electron system. The clusters are interesting model systems that are discussed in the context of wetting of graphene surfaces and polyaromatic hydrocarbons.

Benchmarking uranyl peroxide capsule chemistry in organic media

Energy Technology Data Exchange (ETDEWEB)

Neal, Harrison A.; Nyman, May [Department of Chemistry, Oregon State University, Corvallis, OR (United States); Szymanowski, Jennifer; Fein, Jeremy B.; Burns, Peter C. [Department of Civil and Environmental Engineering and Earth Sciences, University of Notre Dame, Notre Dame, IN (United States)

2017-01-03

Uranyl peroxide capsules are a recent addition to polyoxometalate (POM) chemistry. Ten years of development has ensued only in water, while transition metal POMs are commonly exploited in aqueous and organic media, controlled by counterions or ligation to render the clusters hydrophilic or hydrophobic. Here, new uranyl POM behavior is recognized in organic media, including (1) stabilization and immobilization of encapsulated hydrophilic countercations, identified by Li nuclear magnetic resonance (NMR) spectroscopy, (2) formation of new cluster species upon phase transfer, (3) extraction of uranyl clusters from different starting materials including simulated spent nuclear fuel, (4) selective phase transfer of one cluster type from a mixture, and (5) phase transfer of clusters from both acidic and alkaline media. The capsule morphology of the uranyl POMs renders accurate characterization by X-ray scattering, including the distinction of geometrically similar clusters. Compositional analysis of the aqueous phase post-extraction provided a quantitative determination of the ion exchange process that enables transfer of the clusters into the organic phase. Preferential partitioning of uranyl POMs into organic media presents new frontiers in metal ion behavior and chemical reactions in the confined space of the cluster capsules in hydrophobic media, as well as the reactivity of clusters at the organic/aqueous interface. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Benchmarking uranyl peroxide capsule chemistry in organic media

International Nuclear Information System (INIS)

Neal, Harrison A.; Nyman, May; Szymanowski, Jennifer; Fein, Jeremy B.; Burns, Peter C.

2017-01-01

Uranyl peroxide capsules are a recent addition to polyoxometalate (POM) chemistry. Ten years of development has ensued only in water, while transition metal POMs are commonly exploited in aqueous and organic media, controlled by counterions or ligation to render the clusters hydrophilic or hydrophobic. Here, new uranyl POM behavior is recognized in organic media, including (1) stabilization and immobilization of encapsulated hydrophilic countercations, identified by Li nuclear magnetic resonance (NMR) spectroscopy, (2) formation of new cluster species upon phase transfer, (3) extraction of uranyl clusters from different starting materials including simulated spent nuclear fuel, (4) selective phase transfer of one cluster type from a mixture, and (5) phase transfer of clusters from both acidic and alkaline media. The capsule morphology of the uranyl POMs renders accurate characterization by X-ray scattering, including the distinction of geometrically similar clusters. Compositional analysis of the aqueous phase post-extraction provided a quantitative determination of the ion exchange process that enables transfer of the clusters into the organic phase. Preferential partitioning of uranyl POMs into organic media presents new frontiers in metal ion behavior and chemical reactions in the confined space of the cluster capsules in hydrophobic media, as well as the reactivity of clusters at the organic/aqueous interface. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Using Cluster Analysis to Characterize Meaningful Learning in a First-Year University Chemistry Laboratory Course

Science.gov (United States)

Galloway, Kelli R.; Bretz, Stacey Lowery

2015-01-01

The Meaningful Learning in the Laboratory Instrument (MLLI) was designed to measure students' cognitive and affective learning in the university chemistry laboratory. The MLLI was administered at the beginning and the end of the first semester to first-year university chemistry students to measure their expectations and experiences for learning in…

Trinuclear rhenium(III) halide clusters with carboxylate ligands

Science.gov (United States)

Dougan, Jeffrey Steven

Four mono(carboxylato)trirhenium complexes and three bis(carboxylato)trirhenium complexes have been synthesized and characterized, principally by mass spectrometry, with supporting evidence from X-ray diffraction. These compounds represent the first trinuclear rhenium carboxylate complexes. The reactions generally proceed readily under comparatively mild conditions. Mass spectrometry has again proved its usefulness as a technique in the field of metal cluster chemistry, having provided the initial identification of the products of the reactions studied. These compounds provide a further base to which future mass spectra of metal cluster compounds can be compared. Re-examination of a reaction reported by Taha and Wilkinson has also cast considerable doubt onto the validity of a conversion widely reported in the literature that transforms (Re3Cl9) x into [Re2(O2CCH3)4Cl 2]. We believe that the literature result is a consequence of the purity of the metal precursor, and suggest that the starting material in the earlier work may have contained ReCl4 or ReCl5. The importance of mass spectrometry in the characterization of the new compounds synthesized in this project has led to a thorough study of calculated isotopic distributions. The information gathered suggests that for isotopically simple molecules, the choice of algorithm for computing an isotopic distribution is unimportant. However, it is important to compute the mass spectrum of an isotopically complex molecule using an algorithm that can, if desired, show the underlying isotopic fine structure of a peak of interest. In the last chapter of this thesis, the results of a project in chemistry education research are presented. Predicting the success of students in general chemistry has long been of interest to the chemistry education community, and several factors have been identified as contributing factors. An off-hand comment by a student inspired an examination of whether continuity with the same instructor for

Oxetanes: Recent Advances in Synthesis, Reactivity, and Medicinal Chemistry.

Science.gov (United States)

Bull, James A; Croft, Rosemary A; Davis, Owen A; Doran, Robert; Morgan, Kate F

2016-10-12

The four-membered oxetane ring has been increasingly exploited for its contrasting behaviors: its influence on physicochemical properties as a stable motif in medicinal chemistry and its propensity to undergo ring-opening reactions as a synthetic intermediate. These applications have driven numerous studies into the synthesis of new oxetane derivatives. This review takes an overview of the literature for the synthesis of oxetane derivatives, concentrating on advances in the last five years up to the end of 2015. These methods are clustered by strategies for preparation of the ring and further derivatization of preformed oxetane-containing building blocks. Examples of the use of oxetanes in medicinal chemistry are reported, including a collation of oxetane derivatives appearing in recent patents for medicinal chemistry applications. Finally, examples of oxetane derivatives in ring-opening and ring-expansion reactions are described.

Sustainable technological development in chemistry. Improving the quality of life through chemistry and agriculture

Energy Technology Data Exchange (ETDEWEB)

NONE

1999-08-01

The importance of agricultural products, their potential conversion to energy sources and their applications for fibre-reinforced construction materials is emphasized. Another potentially important technology is the conversion of sunlight into electricity such as occurs in the leaves of plants. Parallels with nature exist, even though conversions with inorganic materials have, until now, been promising. The ability to control chemical reactions is the subject throughout all the following chapters. The goal is to achieve high reaction efficiencies and to use fewer basic materials, both of which will lead to a reduction in environmental stress. Sustainable developments in chemistry can be described by two approaches: (1) Improvements in society, with challenges for chemistry; and (2) Improvement in the chemical sector itself. Both approaches are dealt with in this report. Five areas for development have been chosen in the discussions for `DTO-Chemie`: Integrated plant conversion (IPC), in particular Valorisation of plant parts for raw materials and energy; Biomass conversion (C1 Chemistry), in particular Technologies for (among others) C1-based chemicals and energy carriers; Photovoltaic cells (PSC), in particular Technologies for the conversion of solar light into electricity; Process Technology in Fine chemistry (PFC), in particular Methodology of manufacturing processes for Fine chemicals; and Sustainable Construction Materials (FRC); in particular Techniques for using fibre-reinforced composites in construction applications. These areas can be viewed as clusters of technologies, with a strong chemistry and agricultural component, which are necessary for achieving a sustainable future. Furthermore, it is important to recognise that technology requires a progressive development (technology lifecycle). The five areas of technology development are tested against a number of criteria: (1) Sustainability / leap / volume; (2) Horizon 2050; (3) Commitment from industry

Embedded Cluster Models for Reactivity of the Hydrated Electron

Czech Academy of Sciences Publication Activity Database

Uhlig, Frank; Jungwirth, Pavel

2013-01-01

Roč. 227, č. 11 (2013), s. 1583-1593 ISSN 0942-9352 R&D Projects: GA ČR GBP208/12/G016 Institutional support: RVO:61388963 Keywords : hydrated electron * clusters * reactivity * ab initio molecular dynamics Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.178, year: 2013

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

Low temperature surface chemistry and nanostructures

Science.gov (United States)

Sergeev, G. B.; Shabatina, T. I.

2002-03-01

The new scientific field of low temperature surface chemistry, which combines the low temperature chemistry (cryochemistry) and surface chemistry approaches, is reviewed in this paper. One of the most exciting achievements in this field of science is the development of methods to create highly ordered hybrid nanosized structures on different organic and inorganic surfaces and to encapsulate nanosized metal particles in organic and polymer matrices. We consider physical and chemical behaviour for the systems obtained by co-condensation of the components vapours on the surfaces cooled down to 4-10 and 70-100 K. In particular the size effect of both types, the number of atoms in the reactive species structure and the thickness of growing co-condensate film, on the chemical activity of the system is analysed in detail. The effect of the internal mechanical stresses on the growing interfacial co-condensate film formation and on the generation of fast (explosive) spontaneous reactions at low temperatures is discussed. The examples of unusual chemical interactions of metal atoms, clusters and nanosized particles, obtained in co-condensate films on the cooled surfaces under different conditions, are presented. The examples of highly ordered surface and volume hybrid nanostructures formation are analysed.

A grand unified model for liganded gold clusters

Science.gov (United States)

Xu, Wen Wu; Zhu, Beien; Zeng, Xiao Cheng; Gao, Yi

2016-12-01

A grand unified model (GUM) is developed to achieve fundamental understanding of rich structures of all 71 liganded gold clusters reported to date. Inspired by the quark model by which composite particles (for example, protons and neutrons) are formed by combining three quarks (or flavours), here gold atoms are assigned three `flavours' (namely, bottom, middle and top) to represent three possible valence states. The `composite particles' in GUM are categorized into two groups: variants of triangular elementary block Au3(2e) and tetrahedral elementary block Au4(2e), all satisfying the duet rule (2e) of the valence shell, akin to the octet rule in general chemistry. The elementary blocks, when packed together, form the cores of liganded gold clusters. With the GUM, structures of 71 liganded gold clusters and their growth mechanism can be deciphered altogether. Although GUM is a predictive heuristic and may not be necessarily reflective of the actual electronic structure, several highly stable liganded gold clusters are predicted, thereby offering GUM-guided synthesis of liganded gold clusters by design.

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

Uptake of methanol on mixed HNO3/H2O clusters: An absolute pickup cross section

Czech Academy of Sciences Publication Activity Database

Pysanenko, Andriy; Lengyel, Jozef; Fárník, Michal

2018-01-01

Roč. 148, č. 15 (2018), č. článku 154301. ISSN 0021-9606 R&D Projects: GA ČR(CZ) GA17-04068S Institutional support: RVO:61388955 Keywords : large water clusters * aerosol nucleation precursors * sulfuric-acid * electron ionization * ice nanoparticles Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 2.965, year: 2016

NATO Advanced Research Workshop on Physics and Chemistry of Finite Systems : from Clusters to Crystals

CERN Document Server

Khanna, S; Rao, B

1992-01-01

Recent innovations in experimental techniques such as molecular and cluster beam epitaxy, supersonic jet expansion, matrix isolation and chemical synthesis are increasingly enabling researchers to produce materials by design and with atomic dimension. These materials constrained by sire, shape, and symmetry range from clusters containing as few as two atoms to nanoscale materials consisting of thousands of atoms. They possess unique structuraI, electronic, magnetic and optical properties that depend strongly on their size and geometry. The availability of these materials raises many fundamental questions as weIl as technological possibilities. From the academic viewpoint, the most pertinent question concerns the evolution of the atomic and electronic structure of the system as it grows from micro clusters to crystals. At what stage, for example, does the cluster look as if it is a fragment of the corresponding crystal. How do electrons forming bonds in micro-clusters transform to bands in solids? How do the s...

Simultaneous assessment of phase chemistry, phase abundance and bulk chemistry with statistical electron probe micro-analyses: Application to cement clinkers

Energy Technology Data Exchange (ETDEWEB)

Wilson, William; Krakowiak, Konrad J.; Ulm, Franz-Josef, E-mail: ulm@mit.edu

2014-01-15

According to recent developments in cement clinker engineering, the optimization of chemical substitutions in the main clinker phases offers a promising approach to improve both reactivity and grindability of clinkers. Thus, monitoring the chemistry of the phases may become part of the quality control at the cement plants, along with the usual measurements of the abundance of the mineralogical phases (quantitative X-ray diffraction) and the bulk chemistry (X-ray fluorescence). This paper presents a new method to assess these three complementary quantities with a single experiment. The method is based on electron microprobe spot analyses, performed over a grid located on a representative surface of the sample and interpreted with advanced statistical tools. This paper describes the method and the experimental program performed on industrial clinkers to establish the accuracy in comparison to conventional methods. -- Highlights: •A new method of clinker characterization •Combination of electron probe technique with cluster analysis •Simultaneous assessment of phase abundance, composition and bulk chemistry •Experimental validation performed on industrial clinkers.

Simultaneous assessment of phase chemistry, phase abundance and bulk chemistry with statistical electron probe micro-analyses: Application to cement clinkers

International Nuclear Information System (INIS)

Wilson, William; Krakowiak, Konrad J.; Ulm, Franz-Josef

2014-01-01

According to recent developments in cement clinker engineering, the optimization of chemical substitutions in the main clinker phases offers a promising approach to improve both reactivity and grindability of clinkers. Thus, monitoring the chemistry of the phases may become part of the quality control at the cement plants, along with the usual measurements of the abundance of the mineralogical phases (quantitative X-ray diffraction) and the bulk chemistry (X-ray fluorescence). This paper presents a new method to assess these three complementary quantities with a single experiment. The method is based on electron microprobe spot analyses, performed over a grid located on a representative surface of the sample and interpreted with advanced statistical tools. This paper describes the method and the experimental program performed on industrial clinkers to establish the accuracy in comparison to conventional methods. -- Highlights: •A new method of clinker characterization •Combination of electron probe technique with cluster analysis •Simultaneous assessment of phase abundance, composition and bulk chemistry •Experimental validation performed on industrial clinkers

Protactinium and the intersection of actinide and transition metal chemistry

Energy Technology Data Exchange (ETDEWEB)

Wilson, Richard E.; De Sio, Stephanie; Vallet, Valérie

2018-02-12

The role of the 5f and 6d orbitals in the chemistry of the actinide elements has been of considerable interest since their discovery and synthesis. Relativistic effects cause the energetics of the 5f and 6d orbitals to change as the actinide series is traversed left to right imparting a rich and complex chemistry. The 5f and 6d atomic states cross in energy at protactinium (Pa), making it a potential intersection between transition metal and actinide chemistries. Herein, we report the synthesis of a Pa-peroxo cluster, A(6)(Pa4O(O-2)(6)F-12) [A = Rb, Cs, (CH3)(4)N], formed in pursuit of an actinide polyoxometalate. Quantum chemical calculations at the density functional theory level demonstrate equal 5f and 6d orbital participation in the chemistry of Pa and increasing 5f orbital participation for the heavier actinides. Periodic changes in orbital character to the bonding in the early actinides highlights the influence of the 5f orbitals in their reactivity and chemical structure.

Iron-sulfur clusters as biological sensors: the chemistry of reactions with molecular oxygen and nitric oxide.

Science.gov (United States)

Crack, Jason C; Green, Jeffrey; Thomson, Andrew J; Le Brun, Nick E

2014-10-21

Iron-sulfur cluster proteins exhibit a range of physicochemical properties that underpin their functional diversity in biology, which includes roles in electron transfer, catalysis, and gene regulation. Transcriptional regulators that utilize iron-sulfur clusters are a growing group that exploit the redox and coordination properties of the clusters to act as sensors of environmental conditions including O2, oxidative and nitrosative stress, and metabolic nutritional status. To understand the mechanism by which a cluster detects such analytes and then generates modulation of DNA-binding affinity, we have undertaken a combined strategy of in vivo and in vitro studies of a range of regulators. In vitro studies of iron-sulfur cluster proteins are particularly challenging because of the inherent reactivity and fragility of the cluster, often necessitating strict anaerobic conditions for all manipulations. Nevertheless, and as discussed in this Account, significant progress has been made over the past decade in studies of O2-sensing by the fumarate and nitrate reduction (FNR) regulator and, more recently, nitric oxide (NO)-sensing by WhiB-like (Wbl) and FNR proteins. Escherichia coli FNR binds a [4Fe-4S] cluster under anaerobic conditions leading to a DNA-binding dimeric form. Exposure to O2 converts the cluster to a [2Fe-2S] form, leading to protein monomerization and hence loss of DNA binding ability. Spectroscopic and kinetic studies have shown that the conversion proceeds via at least two steps and involves a [3Fe-4S](1+) intermediate. The second step involves the release of two bridging sulfide ions from the cluster that, unusually, are not released into solution but rather undergo oxidation to sulfane (S(0)) subsequently forming cysteine persulfides that then coordinate the [2Fe-2S] cluster. Studies of other [4Fe-4S] cluster proteins that undergo oxidative cluster conversion indicate that persulfide formation and coordination may be more common than previously

Singlet Oxygen Production and Biological Activity of Hexanuclear Chalcocyanide Rhenium Cluster Complexes [{Re(6)Q(8)}(CN)(6)](4-) (Q = S, Se, Te)

Czech Academy of Sciences Publication Activity Database

Solovieva, A.O.; Kirakci, Kaplan; Ivanov, A.; Kubát, Pavel; Pozmogova, T.N.; Miroshnichenko, S.M.; Vorontsova, E.V.; Chechushkov, A.V.; Trifonova, K.E.; Fufaeva, M.S.; Kretov, E.I.; Mironov, Y.V.; Poveshchenko, A.F.; Lang, Kamil; Shestopalov, M.A.

2017-01-01

Roč. 56, č. 21 (2017), s. 13491-13499 ISSN 0020-1669 R&D Projects: GA ČR(CZ) GA16-15020S Institutional support: RVO:61388980 ; RVO:61388955 Keywords : photophysical properties * silica nanoparticles * molecular-oxygen * iodide cluster * luminescence Subject RIV: CA - Inorganic Chemistry; CF - Physical ; Theoretical Chemistry (UFCH-W) OBOR OECD: Inorganic and nuclear chemistry; Physical chemistry (UFCH-W) Impact factor: 4.857, year: 2016

Triton's Ionosphere: Chemistry and Composition

Science.gov (United States)

Delitsky, Mona

2006-09-01

The ionosphere of Triton was observed by the Voyager spacecraft in 1989 to have a remarkably high electron density of 40,000/cc at its peak altitude. Delitsky et al. (1990) modeled this ionosphere using only N2 and CH4, the constituents of the atmosphere known at that time, and found that, at the extremely cold temperatures in the Triton atmosphere, cluster ions would form. These clusters are created when N+ or N2+ resulting from photolysis or radiolysis accrete neutral N2 molecules and form ions such as (N2+(N2)n). In these clusters, n can be very high, around 50-100, depending on temperature. Cluster ions easily sweep up electrons at the low altitudes where they form (keeping the e- content low) which leads to dissociative recombination. This neutralizes the cluster ions and releases the N2 molecules back into the atmosphere. In 1991, CO and CO2 were observed on Triton (Cruikshank et al. 1991). At Tritonian temperatures, CO will have a very high vapor pressure and could constitute up to 6% of the Triton atmosphere. Any N+ or N2+ will charge exchange with CO (and NO from chemistry) to yield CO+, NO+ and C+. These then become the core ions to the clusters (CO+(N2)n), (NO+(N2)n), or (C+(N2)n). (Delitsky et al. 1992, Delitsky, 1995). Clusters cannot form at higher altitudes and lower pressures and so at the peak altitude, the ionosphere is comprised almost totally of C+ ions. From modeling, CO + hv -> C+ (+ O) does not appear to be an important source of the C+ . Rather, the charge exchange reaction, CO+ + C -> C+ + CO produces the C+ which charge balances the electrons in the ionosphere. Ref: Cruikshank et al., BAAS, 23,1208 (1991);.. Delitsky et al. GRL, 17, 1725 (1990); ..Delitsky et al. Neptune conf, 1992; ..Delitsky, BAAS, 27, 1100 (1995)

Mixed-metal cluster chemistry. 28. Core enlargement of tungsten-iridium clusters with alkynyl, ethyndiyl, and butadiyndiyl reagents.

Science.gov (United States)

Dalton, Gulliver T; Viau, Lydie; Waterman, Susan M; Humphrey, Mark G; Bruce, Michael I; Low, Paul J; Roberts, Rachel L; Willis, Anthony C; Koutsantonis, George A; Skelton, Brian W; White, Allan H

2005-05-02

Reaction of [WIr3(mu-CO)3(CO)8(eta-C5Me5)] (1c) with [W(C[triple bond]CPh)(CO)3(eta-C5H5)] afforded the edge-bridged tetrahedral cluster [W2Ir3(mu4-eta2-C2Ph)(mu-CO)(CO)9(eta-C5H5)(eta-C5Me5)] (3) and the edge-bridged trigonal-bipyramidal cluster [W3Ir3(mu4-eta2-C2Ph)(mu-eta2-C=CHPh)(Cl)(CO)8(eta-C5Me5)(eta-C5H5)2] (4) in poor to fair yield. Cluster 3 forms by insertion of [W(C[triple bond]CPh)(CO)3(eta-C5H5)] into Ir-Ir and W-Ir bonds, accompanied by a change in coordination mode from a terminally bonded alkynyl to a mu4-eta2 alkynyl ligand. Cluster 4 contains an alkynyl ligand interacting with two iridium atoms and two tungsten atoms in a mu4-eta2 fashion, as well as a vinylidene ligand bridging a W-W bond. Reaction of [WIr3(CO)11(eta-C5H5)] (1a) or 1c with [(eta-C5H5)(CO)2 Ru(C[triple bond]C)Ru(CO)2(eta-C5H5)] afforded [Ru2WIr3(mu5-eta2-C2)(mu-CO)3(CO)7(eta-C5H5)2(eta-C5R5)] [R = H (5a), Me (5c)] in low yield, a structural study of 5a revealing a WIr3 butterfly core capped and spiked by Ru atoms; the diruthenium ethyndiyl precursor has undergone Ru-C scission, with insertion of the C2 unit into a W-Ir bond of the cluster precursor. Reaction of [W2Ir2(CO)10(eta-C5H5)2] with the diruthenium ethyndiyl reagent gave [RuW2Ir2{mu4-eta2-(C2C[triple bond]C)Ru(CO)2(eta-C5H5)}(mu-CO)2(CO)6(eta-C5H5)3] (6) in low yield, a structural study of 6 revealing a butterfly W2Ir2 unit capped by a Ru(eta-C5H5) group resulting from Ru-C scission; the terminal C2 of a new ruthenium-bound butadiyndiyl ligand has been inserted into the W-Ir bond. Reaction between 1a, [WIr3(CO)11(eta-C5H4Me)] (1b), or 1c and [(eta-C5H5)(CO)3W(C[triple bond]CC[triple bond]C)W(CO)3(eta-C5H5)] afforded [W2Ir3{mu4-eta2-(C2C[triple bond]C)W(CO)3(eta-C5H5)}(mu-CO)2(CO)2(eta-C5H5)(eta-C5R5)] [R = H (7a), Me (7c); R5 = H4Me (7b)] in good yield, a structural study of 7c revealing it to be a metallaethynyl analogue of 3.

Fluoride Bridges as Structure-Directing Motifs in 3d-4f Cluster Chemistry

DEFF Research Database (Denmark)

Birk, Torben; Pedersen, Kasper; Thuesen, Christian Aa.

2012-01-01

The use of kinetically robust chromium(III) fluorido complexes as synthons for mixed 3d-4f clusters is reported. The tendency toward linear {CrIII–F–LnIII} units dictates the cluster topology. Specifically, we show that reaction of cis-[CrIIIF2(NN)2]NO3 (NN = 1,10-phenanthroline (“phen”) or 2......-nuclear complex and fac-[CrIIIF3L′], with L′ = 1,1,1-tris-((methylamino)methylethane) (“Me3tame”), reacts with [Ln(hfac)3(H2O)2] (hfacH = 1,1,1,5,5,5-hexafluoroacetylacetone) to yield an isostructural series of {Ln3Cr2} (10–14) trigonal bipyramids with no central ligand. The formation of the latter is accompanied...... by a partial solvolysis of the Cr(III) precursor but without formation of insoluble LnF3. The magnetic properties of the gadolinium containing clusters allow quantification of fluoride-mediated, antiferromagnetic Gd–Cr exchange interactions of magnitude between 0.14 cm–1 and 0.71 cm–1 (Ĥ = J12Ŝ1·Ŝ2...

Membrane Order Is a Key Regulator of Divalent Cation-Induced Clustering of PI(3,5)P2 and PI(4,5)P2

Czech Academy of Sciences Publication Activity Database

Sarmento, Maria Joäo; Coutinho, A.; Fedorov, A.; Prieto, M.; Fernandes, F.

2017-01-01

Roč. 33, č. 43 (2017), s. 12463-12477 ISSN 0743-7463 Institutional support: RVO:61388955 Keywords : cell membranes * fluorescence spectroscopy * cluster analysis Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 3.833, year: 2016

Photochemistry of Nitrophenol Molecules and Clusters: Intra- vs Intermolecular Hydrogen Bond Dynamics

Czech Academy of Sciences Publication Activity Database

Grygoryeva, Kateřina; Kubečka, J.; Pysanenko, Andriy; Lengyel, Jozef; Slavíček, Petr; Fárník, Michal

2016-01-01

Roč. 120, č. 24 (2016), s. 4139-4146 ISSN 1089-5639 R&D Projects: GA ČR(CZ) GA15-12386S Institutional support: RVO:61388955 Keywords : photochemistry * clusters * laser techniques Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.847, year: 2016

Characterization of Glutaredoxin Fe-S Cluster-Binding Interactions Using Circular Dichroism Spectroscopy.

Science.gov (United States)

Albetel, Angela-Nadia; Outten, Caryn E

2018-01-01

Monothiol glutaredoxins (Grxs) with a conserved Cys-Gly-Phe-Ser (CGFS) active site are iron-sulfur (Fe-S) cluster-binding proteins that interact with a variety of partner proteins and perform crucial roles in iron metabolism including Fe-S cluster transfer, Fe-S cluster repair, and iron signaling. Various analytical and spectroscopic methods are currently being used to monitor and characterize glutaredoxin Fe-S cluster-dependent interactions at the molecular level. The electronic, magnetic, and vibrational properties of the protein-bound Fe-S cluster provide a convenient handle to probe the structure, function, and coordination chemistry of Grx complexes. However, some limitations arise from sample preparation requirements, complexity of individual techniques, or the necessity for combining multiple methods in order to achieve a complete investigation. In this chapter, we focus on the use of UV-visible circular dichroism spectroscopy as a fast and simple initial approach for investigating glutaredoxin Fe-S cluster-dependent interactions. © 2018 Elsevier Inc. All rights reserved.

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.)

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.

Pressure effect on the structural, elastic, electronic and optical properties of the Zintl phase KAsSn, first principles study

Energy Technology Data Exchange (ETDEWEB)

Guechi, A., E-mail: ab_guechi@yahoo.fr [Institute of Optics and Precision Mechanics, Setif-1 University, 19000 Setif (Algeria); Laboratory of Optoelectronics and Components, Department of Physics, Faculty of Science, Setif-1 University, 19000 Setif (Algeria); Merabet, A. [Institute of Optics and Precision Mechanics, Setif-1 University, 19000 Setif (Algeria); Laboratory of Physics and Mechanics of Metallic Materials, Setif-1 University, 19000 Setif (Algeria); Chegaar, M. [Laboratory of Optoelectronics and Components, Department of Physics, Faculty of Science, Setif-1 University, 19000 Setif (Algeria); Bouhemadou, A. [Laboratory for Developing New Materials and their Characterization, Department of Physics, Faculty of Science, Setif-1 University, 19000 Setif (Algeria); Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Guechi, N. [Laboratory for Developing New Materials and their Characterization, Department of Physics, Faculty of Science, Setif-1 University, 19000 Setif (Algeria)

2015-02-25

Highlights: • KAsSn is interesting in the materials community due to its complex structure and narrow gap. • Physical properties of KAsSn have not taken much attention in previous studies. • The KAsSn structure is shown to be mechanically stable. • KAsSn is predicted to be brittleness and characterized by a weak elastic anisotropy. • Its high absorption in the U.V. energy range shows its use in the optoelectronic devices. - Abstract: In this work, a first-principles study of ternary Zintl phase KAsSn compound using density-functional theory (DFT) method within the generalized gradient approximation developed by Wu–Cohen (GGA-Wc) has been performed. Based on the optimized structural parameter, the electronic structure, elastic and optical properties have been investigated. The calculated lattice constants agree reasonably with the previous results. The effect of high pressure on the structural parameters has been shown. The elastic constants were calculated and satisfy the stability conditions for hexagonal crystal. These indicate that this compound is stable in the studied pressure regime. The single crystal elastic constants (C{sub ij}) and related properties are calculated using the static finite strain technique, moreover the polycrystalline elastic moduli such as bulk modulus, shear modulus, micro-hardness parameter H{sub ν}, Young’s modulus and Poisson’s ratio were estimated using Voigt, Reuss and Hill’s (VRH) approximations. The elastic anisotropy of the KAsSn was also analyzed. On another hand the Debye temperature was obtained from the average sound velocity. Electronic properties have been studied throughout the calculation of band structure, density of states and charge densities. It is shown that this crystal belongs to the semiconductors with a pseudo gap of about 0.34 eV. Furthermore, in order to clarify the optical transitions of this compound, linear optical functions including the complex dielectric function, refractive index

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

Clustering of near clusters versus cluster compactness

International Nuclear Information System (INIS)

Yu Gao; Yipeng Jing

1989-01-01

The clustering properties of near Zwicky clusters are studied by using the two-point angular correlation function. The angular correlation functions for compact and medium compact clusters, for open clusters, and for all near Zwicky clusters are estimated. The results show much stronger clustering for compact and medium compact clusters than for open clusters, and that open clusters have nearly the same clustering strength as galaxies. A detailed study of the compactness-dependence of correlation function strength is worth investigating. (author)

Effect of cluster environment on the electron attachment to 2-nitrophenol

Czech Academy of Sciences Publication Activity Database

Kočišek, Jaroslav; Grygoryeva, Kateřina; Lengyel, Jozef; Fárník, Michal; Fedor, Juraj

2016-01-01

Roč. 70, č. 4 (2016), s. 98-105 ISSN 1434-6060 R&D Projects: GA ČR GJ16-10995Y; GA ČR GA14-14082S Institutional support: RVO:61388955 Keywords : electron attachment * cluster environment * 2-nitrophenol Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.288, year: 2016

Cluster-cluster clustering

International Nuclear Information System (INIS)

Barnes, J.; Dekel, A.; Efstathiou, G.; Frenk, C.S.; Yale Univ., New Haven, CT; California Univ., Santa Barbara; Cambridge Univ., England; Sussex Univ., Brighton, England)

1985-01-01

The cluster correlation function xi sub c(r) is compared with the particle correlation function, xi(r) in cosmological N-body simulations with a wide range of initial conditions. The experiments include scale-free initial conditions, pancake models with a coherence length in the initial density field, and hybrid models. Three N-body techniques and two cluster-finding algorithms are used. In scale-free models with white noise initial conditions, xi sub c and xi are essentially identical. In scale-free models with more power on large scales, it is found that the amplitude of xi sub c increases with cluster richness; in this case the clusters give a biased estimate of the particle correlations. In the pancake and hybrid models (with n = 0 or 1), xi sub c is steeper than xi, but the cluster correlation length exceeds that of the points by less than a factor of 2, independent of cluster richness. Thus the high amplitude of xi sub c found in studies of rich clusters of galaxies is inconsistent with white noise and pancake models and may indicate a primordial fluctuation spectrum with substantial power on large scales. 30 references

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

Communication: Application of state-specific multireference coupled cluster methods to core-level excitations

Czech Academy of Sciences Publication Activity Database

Brabec, Jiří; Bhaskaran-Neir, K.; Govind, N.; Pittner, Jiří

2012-01-01

Roč. 137, č. 17 (2012), s. 171101 ISSN 0021-9606 R&D Projects: GA ČR GAP208/11/2222 Institutional support: RVO:61388955 Keywords : coupled cluster calculations * electron correlations * excited states Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.164, year: 2012

Ab initio nonadiabatic dynamics study of ultrafast radiationless decay over conical intersections illustrated on the Na3F cluster

Czech Academy of Sciences Publication Activity Database

Mitrić, R.; Bonačič-Koutecký, V.; Pittner, Jiří; Lischka, H.

2006-01-01

Roč. 125, č. 2 (2006), 021303 ISSN 0021-9606 Grant - others:Deutsche Forschungsgemeinschaft(DE) SFB 450; Austrian Science Fund(AT) P18411-N19 Institutional research plan: CEZ:AV0Z40400503 Keywords : alkali-halide clusters * optical-responce properties * sodium - fluoride clusters Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.166, year: 2006

Photoinduced Processes in Hydrogen Bonded System: Photodissociation of Imidazole Clusters

Czech Academy of Sciences Publication Activity Database

Poterya, Viktoriya; Profant, V.; Fárník, Michal; Šištík, L.; Slavíček, P.; Buck, U.

2009-01-01

Roč. 113, č. 52 (2009), s. 14583-14590 ISSN 1089-5639 R&D Projects: GA AV ČR KAN400400651; GA AV ČR KJB400400902; GA ČR GA203/09/0422 Institutional research plan: CEZ:AV0Z40400503 Keywords : scattering analysis * molecules * imidazole clusters Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.899, year: 2009

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.

Nickel group cluster anion reactions with carbon monoxide: Rate coefficients and chemisorption efficiency

Science.gov (United States)

Hintz, Paul A.; Ervin, Kent M.

1994-04-01

Reactions of Ni-n(n=3-10), Pd-n(n=3-8), and Pt-n(n=3-7) with CO are studied in a flow tube reactor. Bimolecular rate coefficients are measured for the association reaction of CO adsorbing on the cluster surface. The rate coefficients range from about 10% of the collision rate for the trimer anions to near the collision rate for clusters larger than four atoms. The maximum number of CO molecules that bind to each cluster is determined. Whereas the saturation limits for nickel are typical for an 18 electron transition metal, the limits for platinum are lower, reflecting the electron deficient structures observed in condensed phase chemistry. The CO saturated palladium clusters represent the first examples of saturated binary palladium carbonyl compounds. Comparisons are made to similar studies on metal cation and neutral clusters and also to surface scattering studies of nickel group metals.

Marine data users clustering using data mining technique

Directory of Open Access Journals (Sweden)

Farnaz Ghiasi

2015-09-01

Full Text Available The objective of this research is marine data users clustering using data mining technique. To achieve this objective, marine organizations will enable to know their data and users requirements. In this research, CRISP-DM standard model was used to implement the data mining technique. The required data was extracted from 500 marine data users profile database of Iranian National Institute for Oceanography and Atmospheric Sciences (INIOAS from 1386 to 1393. The TwoStep algorithm was used for clustering. In this research, patterns was discovered between marine data users such as student, organization and scientist and their data request (Data source, Data type, Data set, Parameter and Geographic area using clustering for the first time. The most important clusters are: Student with International data source, Chemistry data type, “World Ocean Database” dataset, Persian Gulf geographic area and Organization with Nitrate parameter. Senior managers of the marine organizations will enable to make correct decisions concerning their existing data. They will direct to planning for better data collection in the future. Also data users will guide with respect to their requests. Finally, the valuable suggestions were offered to improve the performance of marine organizations.

Modelling of Krn+ Clusters (n = 2 - 20) I. Structures and Energetics

Czech Academy of Sciences Publication Activity Database

Kalus, R.; Paidarová, Ivana; Hrivňák, D.; Paška, P.; Gadea, F. X.

2003-01-01

Roč. 294, č. 2 (2003), s. 141-153 ISSN 0301-0104 R&D Projects: GA ČR GA203/00/1025; GA ČR GA203/01/1274 Institutional research plan: CEZ:AV0Z4040901 Keywords : cluster modelling * rare-gas ions * an initio potential Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.070, year: 2003

Surface chemistry manipulation of gold nanorods preserves optical properties for bio-imaging applications

Energy Technology Data Exchange (ETDEWEB)

Polito, Anthony B.; Maurer-Gardner, Elizabeth I.; Hussain, Saber M., E-mail: saber.hussain@us.af.mil [Air Force Research Laboratory, Molecular Bioeffects Branch, Bioeffects Division, Human Effectiveness Directorate (United States)

2015-12-15

Due to their anisotropic shape, gold nanorods (GNRs) possess a number of advantages for biosystem use including, enhanced surface area and tunable optical properties within the near-infrared (NIR) region. However, cetyl trimethylammonium bromide-related cytotoxicity, overall poor cellular uptake following surface chemistry modifications, and loss of NIR optical properties due to material intracellular aggregation in combination remain as obstacles for nanobased biomedical GNR applications. In this article, we report that tannic acid-coated 11-mercaptoundecyl trimethylammonium bromide (MTAB) GNRs (MTAB-TA) show no significant decrease in either in vitro cell viability or stress activation after exposures to A549 human alveolar epithelial cells. In addition, MTAB-TA GNRs demonstrate a substantial level of cellular uptake while displaying a unique intracellular clustering pattern. This clustering pattern significantly reduces intracellular aggregation, preserving the GNRs NIR optical properties, vital for biomedical imaging applications. These results demonstrate how surface chemistry modifications enhance biocompatibility, allow for higher rate of internalization with low intracellular aggregation of MTAB-TA GNRs, and identify them as prime candidates for use in nanobased bio-imaging applications.Graphical Abstract.

Ion collision-induced chemistry in pure and mixed loosely bound clusters of coronene and C60 molecules.

Science.gov (United States)

Domaracka, Alicja; Delaunay, Rudy; Mika, Arkadiusz; Gatchell, Michael; Zettergren, Henning; Cederquist, Henrik; Rousseau, Patrick; Huber, Bernd A

2018-05-23

Ionization, fragmentation and molecular growth have been studied in collisions of 22.5 keV He2+- or 3 keV Ar+-projectiles with pure loosely bound clusters of coronene (C24H12) molecules or with loosely bound mixed C60-C24H12 clusters by using mass spectrometry. The heavier and slower Ar+ projectiles induce prompt knockout-fragmentation - C- and/or H-losses - from individual molecules and highly efficient secondary molecular growth reactions before the clusters disintegrate on picosecond timescales. The lighter and faster He2+ projectiles have a higher charge and the main reactions are then ionization by ions that are not penetrating the clusters. This leads mostly to cluster fragmentation without molecular growth. However, here penetrating collisions may also lead to molecular growth but to a much smaller extent than with 3 keV Ar+. Here we present fragmentation and molecular growth mass distributions with 1 mass unit resolution, which reveals that the same numbers of C- and H-atoms often participate in the formation and breaking of covalent bonds inside the clusters. We find that masses close to those with integer numbers of intact coronene molecules, or with integer numbers of both intact coronene and C60 molecules, are formed where often one or several H-atoms are missing or have been added on. We also find that super-hydrogenated coronene is formed inside the clusters.

Spectroscopic and Computational Investigations of Stable Radical Anions of Triosmium Benzoheterocycle Clusters

Czech Academy of Sciences Publication Activity Database

Nervi, C.; Gobetto, R.; Milone, L.; Viale, A.; Rosenberg, E.; Rokhsana, D.; Fiedler, Jan

2003-01-01

Roč. 9, - (2003), s. 5749-5756 ISSN 0947-6539 R&D Projects: GA MŠk OC D15.10; GA ČR GA203/03/0821 Institutional research plan: CEZ:AV0Z4040901 Keywords : cluster compounds * electron transfer * osmium Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.353, year: 2003

Perturbative triples correction for explicitly correlated Mukherjee's state-specific coupled cluster method

Czech Academy of Sciences Publication Activity Database

Demel, Ondřej; Kedžuch, S.; Noga, J.; Pittner, Jiří

2013-01-01

Roč. 111, 16-17 (2013), s. 2477-2488 ISSN 0026-8976 R&D Projects: GA ČR GPP208/10/P041; GA ČR GAP208/11/2222 Institutional support: RVO:61388955 Keywords : explicitly correlated * coupled cluster * multireference Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.642, year: 2013

Spectral shifts and structures of phenol center dot center dot center dot Ar-n clusters

Czech Academy of Sciences Publication Activity Database

Armentano, A.; Černý, Jiří; Riese, M.; Taherkhani, M.; Ben Yezzar, M.; Muller-Dethlefs, K.

2011-01-01

Roč. 13, č. 13 (2011), s. 6077-6084 ISSN 1463-9076 Institutional research plan: CEZ:AV0Z50520701 Keywords : VAN-DER-WAALS * BENZENE-ARGON CLUSTERS * INFRARED-SPECTRA Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.573, year: 2011

Interpretation of custom designed Illumina genotype cluster plots for targeted association studies and next-generation sequence validation

Directory of Open Access Journals (Sweden)

Tindall Elizabeth A

2010-02-01

Full Text Available Abstract Background High-throughput custom designed genotyping arrays are a valuable resource for biologically focused research studies and increasingly for validation of variation predicted by next-generation sequencing (NGS technologies. We investigate the Illumina GoldenGate chemistry using custom designed VeraCode and sentrix array matrix (SAM assays for each of these applications, respectively. We highlight applications for interpretation of Illumina generated genotype cluster plots to maximise data inclusion and reduce genotyping errors. Findings We illustrate the dramatic effect of outliers in genotype calling and data interpretation, as well as suggest simple means to avoid genotyping errors. Furthermore we present this platform as a successful method for two-cluster rare or non-autosomal variant calling. The success of high-throughput technologies to accurately call rare variants will become an essential feature for future association studies. Finally, we highlight additional advantages of the Illumina GoldenGate chemistry in generating unusually segregated cluster plots that identify potential NGS generated sequencing error resulting from minimal coverage. Conclusions We demonstrate the importance of visually inspecting genotype cluster plots generated by the Illumina software and issue warnings regarding commonly accepted quality control parameters. In addition to suggesting applications to minimise data exclusion, we propose that the Illumina cluster plots may be helpful in identifying potential in-put sequence errors, particularly important for studies to validate NGS generated variation.

Dispersed metal cluster catalysts by design. Synthesis, characterization, structure, and performance

Energy Technology Data Exchange (ETDEWEB)

Arslan, Ilke [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Dixon, David A. [Univ. of Alabama, Tuscaloosa, AL (United States); Gates, Bruce C. [Univ. of California, Davis, CA (United States); Katz, Alexander [Univ. of California, Berkeley, CA (United States)

2015-09-30

To understand the class of metal cluster catalysts better and to lay a foundation for the prediction of properties leading to improved catalysts, we have synthesized metal catalysts with well-defined structures and varied the cluster structures and compositions systematically—including the ligands bonded to the metals. These ligands include supports and bulky organics that are being tuned to control both the electron transfer to or from the metal and the accessibility of reactants to influence catalytic properties. We have developed novel syntheses to prepare these well-defined catalysts with atomic-scale control the environment by choice and placement of ligands and applied state-of-the art spectroscopic, microscopic, and computational methods to determine their structures, reactivities, and catalytic properties. The ligands range from nearly flat MgO surfaces to enveloping zeolites to bulky calixarenes to provide controlled coverages of the metal clusters, while also enforcing unprecedented degrees of coordinative unsaturation at the metal site—thereby facilitating bonding and catalysis events at exposed metal atoms. With this wide range of ligand properties and our arsenal of characterization tools, we worked to achieve a deep, fundamental understanding of how to synthesize robust supported and ligand-modified metal clusters with controlled catalytic properties, thereby bridging the gap between active site structure and function in unsupported and supported metal catalysts. We used methods of organometallic and inorganic chemistry combined with surface chemistry for the precise synthesis of metal clusters and nanoparticles, characterizing them at various stages of preparation and under various conditions (including catalytic reaction conditions) and determining their structures and reactivities and how their catalytic properties depend on their compositions and structures. Key characterization methods included IR, NMR, and EXAFS spectroscopies to identify

Synthesis, characterisation and some chemistry of C- and B-substituted carboxylic acids of cobalt bis(dicarbollide)

Czech Academy of Sciences Publication Activity Database

Nekvinda, Jan; Šícha, Václav; Hnyk, Drahomír; Grüner, Bohumír

2014-01-01

Roč. 43, č. 13 (2014), s. 5106-5120 ISSN 1477-9226 R&D Projects: GA AV ČR IAAX00320901 Institutional support: RVO:61388980 Keywords : BORON-CLUSTER COMPOUNDS * EFFICIENT EXTRACTANTS * ACTINIDE EXTRACTIONS Subject RIV: CA - Inorganic Chemistry Impact factor: 4.197, year: 2014

A new family of Ln₇ clusters with an ideal D(3h) metal-centered trigonal prismatic geometry, and SMM and photoluminescence behaviors.

Science.gov (United States)

Mazarakioti, Eleni C; Poole, Katye M; Cunha-Silva, Luis; Christou, George; Stamatatos, Theocharis C

2014-08-14

The first use of the flexible Schiff base ligand N-salicylidene-2-aminocyclohexanol in metal cluster chemistry has afforded a new family of Ln7 clusters with ideal D(3h) point group symmetry and metal-centered trigonal prismatic topology; solid-state and solution studies revealed SMM and photoluminescence behaviors.

FEATURES OF ISLET-LIKE CLUSTERS GENERATION IN PANCREATIC DUCTAL CELL MOLOLAYER CULTURING

Directory of Open Access Journals (Sweden)

L. A. Kirsanova

2012-01-01

Full Text Available Newborn rabbit pancreatic cell monolayer was obtained as we described earlier.The cultivated epithelial cells were shown by immunofluorescence to express special ductal marker CK19 and were insulin-and glucagon- negative for 10–15 days. A few fusiforms of nestin-positive cells were found in monolayer. Over 2 weeks in serum-free medium the plaques of epithelial cells became crowded and formed 3-dimentional structures – islet- like clusters. Islet-like clusters contain some insulin- and glucagon-positive cells recognized by immunohysto- chemistry staining. Pancreatic endocrine cell generation in 3-dimentional structures is discussed. 

Composition dependent selectivity in the coadsorption of H2O and CO on pure and binary silver-gold clusters

Science.gov (United States)

Fleischer, Irene; Popolan, Denisia M.; Krstić, Marjan; Bonačić-Koutecký, Vlasta; Bernhardt, Thorsten M.

2013-04-01

Small cationic gold clusters exhibit a strong affinity toward carbon monoxide. This prevents the coadsorption of water which would be the first step of a catalytic water gas shift chemistry on these clusters. In a gas phase ion trap experiment with mass selected AgnAum+ it was however possible to demonstrate that the replacement of gold by silver atoms in triatomic cluster ions liberates sites for H2O adsorption. The resulting observed coadsorption effect occurs at a cross-over in the molecular binding energies of carbon monoxide and water to these clusters determined by reaction kinetics measurements and first principles calculations.

Observation and Theoretical Description of Periodic Geometric Rearrangement in Electronically Excited Nonstoichiometric Sodium-Fluoride Clusters

Czech Academy of Sciences Publication Activity Database

Vajda, Š.; Lupulescu, C.; Merli, A.; Budzyn, F.; Wöste, L.; Hartmann, M.; Pittner, Jiří; Bonačič-Koutecký, V.

2002-01-01

Roč. 89, č. 21 (2002), s. 213404.1-213404.4 ISSN 0031-9007 Institutional research plan: CEZ:AV0Z4040901 Keywords : alkali-halide clusters * Wigner distribution approach * ab initio Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 7.323, year: 2002

Study on interaction of swift cluster ion beam with matter and irradiation effect (Joint research)

International Nuclear Information System (INIS)

Saito, Yuichi; Shibata, Hiromi

2010-07-01

This review covers results of the 'Study of interaction on swift cluster ion beam with matter and irradiation effect' supported by the Interorganization Atomic Energy Research Program from 2006FY to 2008FY. It is composed of a research abstract for each sub-group with viewgraphs which were presented at the group meeting held on March 2009 or 'Meeting of High LET radiation -From fundamental study among physics, chemistry and biology to medical applications-' sponsored by Japan Society of Radiation Chemistry, cosponsored by this research group. (author)

Microstructure and surface chemistry of amorphous alloys important to their friction and wear behavior

Science.gov (United States)

Miyoshi, K.; Buckley, D. H.

1986-01-01

An investigation was conducted to examine the microstructure and surface chemistry of amorphous alloys, and their effects on tribological behavior. The results indicate that the surface oxide layers present on amorphous alloys are effective in providing low friction and a protective film against wear in air. Clustering and crystallization in amorphous alloys can be enhanced as a result of plastic flow during the sliding process at a low sliding velocity, at room temperature. Clusters or crystallines with sizes to 150 nm and a diffused honeycomb-shaped structure are produced on sizes to 150 nm and a diffused honeycomb-shaped structure are produced on the wear surface. Temperature effects lead to drastic changes in surface chemistry and friction behavior of the alloys at temperatures to 750 C. Contaminants can come from the bulk of the alloys to the surface upon heating and impart to the surface oxides at 350 C and boron nitride above 500 C. The oxides increase friction while the boron nitride reduces friction drastically in vacuum.

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

Exploring the Potential of Different-Sized Supported Subnanometer Pt Clusters as Catalysts for Wet Chemical Applications

KAUST Repository

Rondelli, Manuel; Zwaschka, Gregor; Krause, Maximilian; Rö tzer, Marian D.; Hedhili, Mohamed N.; Hogerl, Manuel Peter; D’ Elia, Valerio; Schweinberger, Florian F.; Basset, Jean-Marie; Heiz, Ueli

2017-01-01

as catalysts for organic chemistry transformations in solution has not been explored. To this end, single Pt atoms and Pt clusters with two narrow size distributions were prepared in the UHV and applied for the hydrogenation of p-chloronitrobenzene to p

Iterative universal state selective correction for the Brillouin-Wigner multireference coupled-cluster theory

Czech Academy of Sciences Publication Activity Database

Banik, Subrata; Ravichandran, Lalitha; Brabec, J.; Hubač, I.; Kowalski, K.; Pittner, Jiří

2015-01-01

Roč. 142, č. 11 (2015), s. 114106 ISSN 0021-9606 R&D Projects: GA MŠk LH13117; GA ČR GAP208/11/2222 Institutional support: RVO:61388955 Keywords : QUADRUPLY EXCITED CLUSTERS * QUASI-DEGENERATE STATES * DOUBLE-EXCITATION MODEL Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.894, year: 2015

Surface Collisions of Small Cluster Ions at Incident Energies 10-102 eV

Czech Academy of Sciences Publication Activity Database

Herman, Zdeněk

2004-01-01

Roč. 233, - (2004), s. 361-371 ISSN 1387-3806 R&D Projects: GA MŠk ME 561 Grant - others:XE(CZ) EURATOM-IPP.CR Institutional research plan: CEZ:AV0Z4040901 Keywords : surface collisions * cluster ions * unimolecular dissociation Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.235, year: 2004

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.)

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...

Water-soluble octahedral molybdenum cluster compounds Na2[Mo6I8(N3)6] and Na2[Mo6I8(NCS)6]: Syntheses, luminescence, and in vitro studies

Czech Academy of Sciences Publication Activity Database

Kirakci, Kaplan; Kubát, Pavel; Kučeráková, Monika; Šícha, Václav; Gbelcová, H.; Lovecká, P.; Grznárová, P.; Ruml, T.; Lang, Kamil

2016-01-01

Roč. 441, FEB (2016), s. 42-49 ISSN 0020-1693 R&D Projects: GA ČR GA13-05114S Institutional support: RVO:61388980 ; RVO:61388955 ; RVO:68378271 Keywords : Cluster compounds * Luminescence * Singlet oxygen * Toxicity Subject RIV: CA - Inorganic Chemistry; CF - Physical ; Theoretical Chemistry (UFCH-W); CF - Physical ; Theoretical Chemistry (FZU-D) Impact factor: 2.002, year: 2016

Coordination polymers: trapping of radionuclides and chemistry of tetravalent actinides (Th, U) carboxylates

International Nuclear Information System (INIS)

Falaise, Clement

2014-01-01

The use of nuclear energy obviously raises the question of the presence of radionuclides in the environment. Currently, their mitigation is a major issue associated with nuclear chemistry. This thesis focuses on both the trapping of radionuclides by porous solids called Metal-Organic Frameworks (MOF) and the crystal chemistry of the carboxylate of tetravalent actinides (AnIV). The academic knowledge of the reactivity of carboxylate of AnIV could help the understanding of actinides speciation in environment. We focused on the sequestration of iodine by aluminum based MOF. The functionalization (electron-donor group) of the MOF drastically enhances the iodine capture capacity. The removal of light actinides (Th and U) from aqueous solution was also investigated as well as the stability of (Al)-MOF under γ radiation. More than twenty coordination polymers based on tetravalent actinides have been synthesized and characterized by single crystal X-ray diffraction. The use of controlled hydrolysis promotes the formation of coordination polymers exhibiting polynuclear cluster ([U 4 ], [Th 6 ], [U 6 ] and [U 38 ]). In order to understand the formation of the largest cluster, the ex-situ study of the solvo-thermal synthesis of compound {U 38 } has also been investigated. (author)

Macropolyhedral boron-containing cluster chemistry. Cluster opening and B-frame rearrangement in the reaction of B16H20 with [{(IrCl2(eta(5)-C5Me5)}(2)]. Synchrotron X-ray structures of [(eta(5)-C5Me5)(2)Ir2B16H17Cl] and [(eta(5)-C5Me5)(2)Ir2B16H15Cl

Czech Academy of Sciences Publication Activity Database

Carr, MJ.; Perera, SD.; Jelínek, Tomáš; Kilner, C. A.; Clegg, W.; Štíbr, Bohumil; Kennedy, J.D.

2006-01-01

Roč. 44, - (2006), s. 5221-5224 ISSN 1477-9226 R&D Projects: GA AV ČR(CZ) IAA400320601; GA ČR GA203/05/2646 Grant - others:EPSRC(GB) J/56929; EPSRC(GB) GR/L/49505; EPSRC(GB) R/61949 Institutional research plan: CEZ:AV0Z40320502 Keywords : intercluster bonding intimagy * matallaborane clusters * crystal-structures Subject RIV: CA - Inorganic Chemistry Impact factor: 3.012, year: 2006

Syntheses, and crystal and electronic structures of the new Zintl phases Na2ACdSb2 and K2ACdSb2 (A=Ca, Sr, Ba, Eu, Yb): Structural relationship with Yb2CdSb2 and the solid solutions Sr2-xAxCdSb2, Ba2-xAxCdSb2 and Eu2-xYbxCdSb2

International Nuclear Information System (INIS)

Saparov, Bayrammurad; Saito, Maia; Bobev, Svilen

2011-01-01

Presented are the details of the syntheses, crystal and electronic structures of a new family of Zintl phases Na 2 ACdSb 2 and K 2 ACdSb 2 (A=Ca, Sr, Ba, Eu, Yb), as well as the solid solutions Sr 2-x A x CdSb 2 , Ba 2-x A x CdSb 2 and Eu 2-x Yb x CdSb 2 . The structures of Na 2 ACdSb 2 and K 2 ACdSb 2 (A=Ca, Sr, Ba, Eu, Yb) were determined to be of a new type with the non-centrosymmetric space group Pmc2 1 (no. 26), Pearson symbol oP12, with lattice parameters a=4.684(1)-4.788(1) A; b=9.099(3)-9.117(2) A; c=7.837(1)-8.057(2) A for the Na 2 ACdSb 2 series, and a=4.6637(9)-5.0368(8) A; b=9.100(2)-9.8183(15) A; and c=7.7954(15)-8.4924(13) A for K 2 ACdSb 2 , respectively. The solid solutions Sr 2-x A x CdSb 2 , Ba 2-x A x CdSb 2 and Eu 2-x Yb x CdSb 2 (x∼1) are isostructural and isoelectronic to the recently reported Yb 2 CdSb 2 (space group Cmc2 1 (no. 36), Pearson symbol cP20). All discussed structures are based upon CdSb 2 4- polyanionic layers, similar to the ones observed in Yb 2 CdSb 2 , with various alkali- and/or alkaline-earth cations coordinated to them. Magnetic susceptibility and Seebeck coefficient measurements on selected Eu 2-x Yb x CdSb 2 samples, taken at low temperatures up to 300 K, are also reported. -- Graphical abstract: The quaternary Zintl phases Na 2 ACdSb 2 and K 2 ACdSb 2 (A=Ca, Sr, Ba, Eu, Yb) with novel layered structures have been synthesized for the first time and structurally characterized by single-crystal X-ray diffraction. Reported as well are the results from crystallographic and property studies of the closely related solid solutions Sr 2-x A x CdSb 2 , Ba 2-x A x CdSb 2 (x∼1), and Eu 2-x Yb x CdSb 2 (1 2 ACdSb 2 and K 2 ACdSb 2 (A=Ca, Sr, Ba, Eu, Yb) are new quaternary Zintl phases. → Sr 2-x A x CdSb 2 , Ba 2-x A x CdSb 2 (x∼1), and Eu 2-x Yb x CdSb 2 (1 4 tetrahedra. → Eu 2-x Yb x CdSb 2 (1< x<2) exhibit high Seebeck coefficient (217 μV/K at RT).

Mass spectrometric production of heterogeneous metal clusters using Knudsen cell

Directory of Open Access Journals (Sweden)

Veljković Filip M.

2016-01-01

Full Text Available Knudsen effusion mass spectrometry or high-temperature method of mass spectrometry for decades gives new information about saturated vapor of hardly volatile compounds and it is an important method in the discovery of many new molecules, radicals, ions and clusters present in the gas phase. Since pioneering works until now, this method has been successfully applied to a large number of systems (ores, oxides, ceramics, glass materials, borides, carbides, sulfides, nitrates, metals, fullerenes, etc which led to the establishment of various research branches such as chemistry of clusters. This paper describes the basic principles of Knudsen cell use for both identification of chemical species created in the process of evaporation and determination of their ionization energies. Depending on detected ions intensities and the partial pressure of each gaseous component, as well as on changes in partial pressure with temperature, Knudsen cell mass spectrometry enables the determination of thermodynamic parameters of the tested system. A special attention is paid to its application in the field of small heterogeneous and homogeneous clusters of alkali metals. Furthermore, experimental results for thermodynamic parameters of some clusters, as well as capabilities of non-standard ways of using Knudsen cells in the process of synthesis of new clusters are presented herein. [Projekat Ministarstva nauke Republike Srbije, br. 172019

A Highly Luminescent Hexanuclear Molybdenum Cluster - A Promising Candidate toward Photoactive Materials

Czech Academy of Sciences Publication Activity Database

Kirakci, Kaplan; Kubát, Pavel; Dušek, Michal; Fejfarová, Karla; Šícha, Václav; Mosinger, Jiří; Lang, Kamil

2012-01-01

Roč. 2012, č. 19 (2012), s. 3107-3111 ISSN 1434-1948 R&D Projects: GA ČR(CZ) GAP204/11/0809; GA ČR GAP208/10/1678 Institutional support: RVO:61388980 ; RVO:61388955 ; RVO:68378271 Keywords : cluster compounds * luminescence * molybdenum * organic-inorganic hybrid composites * singlet oxygen Subject RIV: CA - Inorganic Chemistry Impact factor: 3.120, year: 2012

Apparatus for ground water chemistry investigations in field caissons

International Nuclear Information System (INIS)

Cokal, E.J.; Stallings, E.; Walker, R.; Nyhan, J.W.; Polzer, W.L.; Essington, E.H.

1985-01-01

Los Alamos is currently in its second season of ground water chemistry and hydrology experimentation in a field facility that incorporates clusters of six, 3-meter-diameter by 6-meter-deep, soil-filled caissons and required ancillaries. Initial experience gained during the 1983 field season indicated the need for further development of the technology of this type of experimentation supporting hydrologic waste management research. Uniform field application of water/matrix solutions to the caisson, matrix and tracer solution blending/storage, and devices for ground water sampling are discussed

Groundwater Chemistry Regulated by Hydrochemical Processes and Geological Structures: A Case Study in Tongchuan, China

Directory of Open Access Journals (Sweden)

Xinyan Li

2018-03-01

Full Text Available Knowledge of hydrochemical processes in groundwater helps to identify the relationship between geochemical processes and groundwater quality as well as to understand the hydrochemical evaluation of groundwater, which is important for the sustainable management of groundwater resources. This study aims to identify the chemical characteristics of groundwater in the area of Tongchuan City, China. A total of 58 groundwater samples were collected. A hierarchical cluster analysis divided samples into three clusters and six sub-clusters (cluster 1a, 1b, 2a, 2b, 3a, 3b according to hydrochemical facies. Graphical plots of multiple ionic ratios, saturation indices, and ion exchange indices were employed to examine hydrochemical processes that result in different hydrochemical facies of each cluster. Results show the predominance of carbonate and silicate weathering in cluster 1, silicate weathering in cluster 2, and carbonate weathering in cluster 3. Ionic exchange is a ubiquitous process among all clusters. The distribution of clusters is related to the regional geology, which may result in different hydrochemical processes. Two stratigraphic sections identify the differences in hydrochemical processes resulting from complex stratum structures and varied aquifer media. Cluster 2a shows an interesting difference in water chemistry along the groundwater flow path. Further study by oxygen and hydrogen isotope indicated that mixing between Quaternary and the Permian aquifers resulting from faulting is the main reason for the distinctive characteristic of cluster 2a.

Resonant electron attachment to mixed hydrogen/oxygen and deuterium/oxygen clusters

Science.gov (United States)

Renzler, Michael; Kranabetter, Lorenz; Barwa, Erik; Grubwieser, Lukas; Scheier, Paul; Ellis, Andrew M.

2017-11-01

Low energy electron attachment to mixed (H2)x/(O2)y clusters and their deuterated analogs has been investigated for the first time. These experiments were carried out using liquid helium nanodroplets to form the clusters, and the effect of the added electron was then monitored via mass spectrometry. There are some important differences between electron attachment to the pure clusters and to the mixed clusters. A particularly notable feature is the formation of HO2- and H2O- ions from an electron-induced chemical reaction between the two dopants. The chemistry leading to these anions appears to be driven by electron resonances associated with H2 rather than O2. The electron resonances for H2 can lead to dissociative electron attachment (DEA), just as for the free H2 molecule. However, there is evidence that the resonance in H2 can also lead to rapid electron transfer to O2, which then induces DEA of the O2. This kind of excitation transfer has not, as far as we are aware, been reported previously.

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.

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)

Clustering in the stellar abundance space

Science.gov (United States)

Boesso, R.; Rocha-Pinto, H. J.

2018-03-01

We have studied the chemical enrichment history of the interstellar medium through an analysis of the n-dimensional stellar abundance space. This work is a non-parametric analysis of the stellar chemical abundance space. The main goal is to study the stars from their organization within this abundance space. Within this space, we seek to find clusters (in a statistical sense), that is, stars likely to share similar chemo-evolutionary history, using two methods: the hierarchical clustering and the principal component analysis. We analysed some selected abundance surveys available in the literature. For each sample, we labelled the group of stars according to its average abundance curve. In all samples, we identify the existence of a main enrichment pattern of the stars, which we call chemical enrichment flow. This flow is set by the structured and well-defined mean rate at which the abundances of the interstellar medium increase, resulting from the mixture of the material ejected from the stars and stellar mass-loss and interstellar medium gas. One of the main results of our analysis is the identification of subgroups of stars with peculiar chemistry. These stars are situated in regions outside of the enrichment flow in the abundance space. These peculiar stars show a mismatch in the enrichment rate of a few elements, such as Mg, Si, Sc and V, when compared to the mean enrichment rate of the other elements of the same stars. We believe that the existence of these groups of stars with peculiar chemistry may be related to the accretion of planetary material on to stellar surfaces or may be due to production of the same chemical element by different nucleosynthetic sites.

Luminescent Hydrogel Particles Prepared by Self-Assembly of β-Cyclodextrin Polymer and Octahedral Molybdenum Cluster Complexes

Czech Academy of Sciences Publication Activity Database

Kirakci, Kaplan; Šícha, Václav; Holub, Josef; Kubát, Pavel; Lang, Kamil

2014-01-01

Roč. 53, č. 24 (2014), s. 13012-13018 ISSN 0020-1669 R&D Projects: GA ČR GA13-05114S Institutional support: RVO:61388980 ; RVO:61388955 Keywords : Octahedral Molybdenum Cluster * Hydrogel * Luminescence Subject RIV: CA - Inorganic Chemistry Impact factor: 4.762, year: 2014

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...

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.

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....

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.

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

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.

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.

Evidence for nano-Si clusters in amorphous SiO anode materials for rechargeable Li-ion batteries

International Nuclear Information System (INIS)

Sepehri-Amin, H.; Ohkubo, T.; Kodzuka, M.; Yamamura, H.; Saito, T.; Iba, H.; Hono, K.

2013-01-01

Atom probe tomography and high resolution transmission electron microscopy have shown the presence of nano-sized amorphous Si clusters in non-disproportionated amorphous SiO powders are under consideration for anode materials in Li-ion batteries. After Li insertion/extraction, no change was found in the chemistry and structure of the Si clusters. However, Li atoms were found to be trapped at the amorphous SiO phase after Li insertion/extraction, which may be attributed to the large capacity fade after the first charge/discharge cycle

A full-configuration-interaction nuclear orbital approach and application for small doped He clusters

Energy Technology Data Exchange (ETDEWEB)

Lara-Castells, M. P. de, E-mail: delara@iff.csic.es; Aguirre, N. F., E-mail: delara@iff.csic.es; Delgado-Barrio, G., E-mail: delara@iff.csic.es; Villarreal, P., E-mail: delara@iff.csic.es [Instituto de Física Fundamental (CSIC), Serrano 123, 28006 Madrid (Spain); Mitrushchenkov, A. O. [Université Paris-Est, Laboratoire Modélisation et Simulation Multi Echelle, MSME UMR 8208 CNRS, 5 bd Descartes, 77454 Marne-la-Vallée (France)

2015-01-22

An efficient full-configuration-interaction 'nuclear orbital' treatment was developed as a benchmark quantum-chemistry-like method to calculate, ground and excited, fermionic 'solvent' wave-functions and applied to {sup 3}He{sub N} clusters with atomic or molecular impurities [J. Chem. Phys. (Communication) 125, 221101 (2006)]. The main difficulty in handling doped {sup 3}He{sub N} clusters lies in the Fermi-Dirac nuclear statistics, the wide amplitudes of the He-dopant and He-He motions, and the hard-core He-He interaction at short distances. This paper overviews the theoretical approach and its recent applications to energetic, structural and spectroscopic aspects of different dopant-{sup 3}He{sub N} clusters. Preliminary results by using the latest version of the FCI-NO computational implementation, to bosonic Cl{sub 2}(X)-({sup 4}He){sub N} clusters, are also shown.

Semiclassical Hybrid Approach to Condensed Phase Molecular Dynamics: Application to the I2Kr17 Cluster

Czech Academy of Sciences Publication Activity Database

Buchholz, M.; Goletz, Ch. M.; Grossman, F.; Schmidt, B.; Heyda, J.; Jungwirth, Pavel

2012-01-01

Roč. 116, č. 46 (2012), s. 11199-11210 ISSN 1089-5639 R&D Projects: GA ČR GBP208/12/G016 Institutional support: RVO:61388963 Keywords : semiclassical molecular dynamics * cluster * wavepacket * coherence * spectra Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.771, year: 2012

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.

Development and Application of Single-Referenced Perturbation and Coupled-Cluster Theories for Excited Electronic States

Science.gov (United States)

Lee, Timothy J.; Langhoff, Stephen R. (Technical Monitor)

1997-01-01

Recent work on the development of single-reference perturbation theories for the study of excited electronic states will be discussed. The utility of these methods will be demonstrated by comparison to linear-response coupled-cluster excitation energies. Results for some halogen molecules of interest in stratospheric chemistry will be presented.

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

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

Tug of war between AO-hybridization and aromaticity in dictating structures of Li-doped alkali clusters

Science.gov (United States)

Alexandrova, Anastassia N.

2012-04-01

Hybridization of atomic orbitals is a widely appreciated phenomenon in organic chemistry. Here, we demonstrate that hybridization also can dramatically impact the shapes of small all-alkali metal clusters, and oppose σ-aromaticity in defining cluster shapes. The valence-iso-electronic LiNa4- and LiK4- clusters adopt different global minimum structures: LiNa4- is a planar C2v (1A1) species distorted from the perfect pentagon, and LiK4- is a planar square D4h (1A1g) species with Li being in the centre. This effect is rooted in the different degrees of the 2s-2p hybridization in Li in response to binding to Na versus K.

Excess electrons in methanol clusters: Beyond the one-electron picture

Science.gov (United States)

Pohl, Gábor; Mones, Letif; Turi, László

2016-10-01

We performed a series of comparative quantum chemical calculations on various size negatively charged methanol clusters, ("separators=" CH 3 OH ) n - . The clusters are examined in their optimized geometries (n = 2-4), and in geometries taken from mixed quantum-classical molecular dynamics simulations at finite temperature (n = 2-128). These latter structures model potential electron binding sites in methanol clusters and in bulk methanol. In particular, we compute the vertical detachment energy (VDE) of an excess electron from increasing size methanol cluster anions using quantum chemical computations at various levels of theory including a one-electron pseudopotential model, several density functional theory (DFT) based methods, MP2 and coupled-cluster CCSD(T) calculations. The results suggest that at least four methanol molecules are needed to bind an excess electron on a hydrogen bonded methanol chain in a dipole bound state. Larger methanol clusters are able to form stronger interactions with an excess electron. The two simulated excess electron binding motifs in methanol clusters, interior and surface states, correlate well with distinct, experimentally found VDE tendencies with size. Interior states in a solvent cavity are stabilized significantly stronger than electron states on cluster surfaces. Although we find that all the examined quantum chemistry methods more or less overestimate the strength of the experimental excess electron stabilization, MP2, LC-BLYP, and BHandHLYP methods with diffuse basis sets provide a significantly better estimate of the VDE than traditional DFT methods (BLYP, B3LYP, X3LYP, PBE0). A comparison to the better performing many electron methods indicates that the examined one-electron pseudopotential can be reasonably used in simulations for systems of larger size.

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...

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)

Factor-cluster analysis and enrichment study of Mangrove sediments - An example from Mengkabong, Sabah

International Nuclear Information System (INIS)

Praveena, S.M.; Ahmed, A.; Radojevic, M.; Mohd Harun Abdullah; Aris, A.Z.

2007-01-01

This paper examines the tidal effects in the sediment of Mengkabong mangrove forest, Sabah. Generally, all the studied parameters showed high value at high tide compared to low tide. Factor-cluster analyses were adopted to allow the identification of controlling factors at high and low tides. Factor analysis extracted six controlling factors at high tide and seven controlling factors at low tide. Cluster analysis extracted two district clusters at high and low tides. The study showed that factor-cluster analysis application is a useful tool to single out the controlling factors at high and low tides. this will provide a basis for describing the tidal effects in the mangrove sediment. The salinity and electrical conductivity clusters as well as component loadings at high and low tide explained the tidal process where there is high contribution of seawater to mangrove sediments that controls the sediment chemistry. The geo accumulation index (T geo ) values suggest the mangrove sediments are having background concentrations for Al, Cu, Fe and Zn and unpolluted for Pb. (author)

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

Towards large-scale calculations with State-Specific Multireference Coupled Cluster methods: Studies on dodecane, naphthynes, and polycarbenes

Czech Academy of Sciences Publication Activity Database

Brabec, Jiří; Bhaskaran-Neir, K.; Kowalski, K.; Pittner, Jiří; van Dam, H. J. J.

2012-01-01

Roč. 542, 23 July (2012), s. 128-133 ISSN 0009-2614 R&D Projects: GA ČR GAP208/11/2222 Institutional support: RVO:61388955 Keywords : multireference Coupled Cluster (MRCC) methods * molecular systems * polycarbenes Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.145, year: 2012

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

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.

Spectroscopic and computational studies of ionic clusters as models of solvation and atmospheric reactions

Science.gov (United States)

Kuwata, Keith T.

Ionic clusters are useful as model systems for the study of fundamental processes in solution and in the atmosphere. Their structure and reactivity can be studied in detail using vibrational predissociation spectroscopy, in conjunction with high level ab initio calculations. This thesis presents the applications of infrared spectroscopy and computation to a variety of gas-phase cluster systems. A crucial component of the process of stratospheric ozone depletion is the action of polar stratospheric clouds (PSCs) to convert the reservoir species HCl and chlorine nitrate (ClONO2) to photochemically labile compounds. Quantum chemistry was used to explore one possible mechanism by which this activation is effected: Cl- + ClONO2 /to Cl2 + NO3- eqno(1)Correlated ab initio calculations predicted that the direct reaction of chloride ion with ClONO2 is facile, which was confirmed in an experimental kinetics study. In the reaction a weakly bound intermediate Cl2-NO3- is formed, with ~70% of the charge localized on the nitrate moiety. This enables the Cl2-NO3- cluster to be well solvated even in bulk solution, allowing (1) to be facile on PSCs. Quantum chemistry was also applied to the hydration of nitrosonium ion (NO+), an important process in the ionosphere. The calculations, in conjunction with an infrared spectroscopy experiment, revealed the structure of the gas-phase clusters NO+(H2O)n. The large degree of covalent interaction between NO+ and the lone pairs of the H2O ligands is contrasted with the weak electrostatic bonding between iodide ion and H2O. Finally, the competition between ion solvation and solvent self-association is explored for the gas-phase clusters Cl/-(H2O)n and Cl-(NH3)n. For the case of water, vibrational predissociation spectroscopy reveals less hydrogen bonding among H2O ligands than predicted by ab initio calculations. Nevertheless, for n /ge 5, cluster structure is dominated by water-water interactions, with Cl- only partially solvated by the

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

STAR CLUSTERS IN M31. V. EVIDENCE FOR SELF-ENRICHMENT IN OLD M31 CLUSTERS FROM INTEGRATED SPECTROSCOPY

International Nuclear Information System (INIS)

Schiavon, Ricardo P.; Caldwell, Nelson; Conroy, Charlie; Graves, Genevieve J.; Strader, Jay; MacArthur, Lauren A.; Courteau, Stéphane; Harding, Paul

2013-01-01

In the past decade, the notion that globular clusters (GCs) are composed of coeval stars with homogeneous initial chemical compositions has been challenged by growing evidence that they host an intricate stellar population mix, likely indicative of a complex history of star formation and chemical enrichment. Several models have been proposed to explain the existence of multiple stellar populations in GCs, but no single model provides a fully satisfactory match to existing data. Correlations between chemistry and global parameters such as cluster mass or luminosity are fundamental clues to the physics of GC formation. In this Letter, we present an analysis of the mean abundances of Fe, Mg, C, N, and Ca for 72 old GCs from the Andromeda galaxy. We show for the first time that there is a correlation between the masses of GCs and the mean stellar abundances of nitrogen, spanning almost two decades in mass. This result sheds new light on the formation of GCs, providing important constraints on their internal chemical evolution and mass loss history

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.

Weighted similarity-based clustering of chemical structures and bioactivity data in early drug discovery.

Science.gov (United States)

Perualila-Tan, Nolen Joy; Shkedy, Ziv; Talloen, Willem; Göhlmann, Hinrich W H; Moerbeke, Marijke Van; Kasim, Adetayo

2016-08-01

The modern process of discovering candidate molecules in early drug discovery phase includes a wide range of approaches to extract vital information from the intersection of biology and chemistry. A typical strategy in compound selection involves compound clustering based on chemical similarity to obtain representative chemically diverse compounds (not incorporating potency information). In this paper, we propose an integrative clustering approach that makes use of both biological (compound efficacy) and chemical (structural features) data sources for the purpose of discovering a subset of compounds with aligned structural and biological properties. The datasets are integrated at the similarity level by assigning complementary weights to produce a weighted similarity matrix, serving as a generic input in any clustering algorithm. This new analysis work flow is semi-supervised method since, after the determination of clusters, a secondary analysis is performed wherein it finds differentially expressed genes associated to the derived integrated cluster(s) to further explain the compound-induced biological effects inside the cell. In this paper, datasets from two drug development oncology projects are used to illustrate the usefulness of the weighted similarity-based clustering approach to integrate multi-source high-dimensional information to aid drug discovery. Compounds that are structurally and biologically similar to the reference compounds are discovered using this proposed integrative approach.

ABCluster: the artificial bee colony algorithm for cluster global optimization.

Science.gov (United States)

Zhang, Jun; Dolg, Michael

2015-10-07

Global optimization of cluster geometries is of fundamental importance in chemistry and an interesting problem in applied mathematics. In this work, we introduce a relatively new swarm intelligence algorithm, i.e. the artificial bee colony (ABC) algorithm proposed in 2005, to this field. It is inspired by the foraging behavior of a bee colony, and only three parameters are needed to control it. We applied it to several potential functions of quite different nature, i.e., the Coulomb-Born-Mayer, Lennard-Jones, Morse, Z and Gupta potentials. The benchmarks reveal that for long-ranged potentials the ABC algorithm is very efficient in locating the global minimum, while for short-ranged ones it is sometimes trapped into a local minimum funnel on a potential energy surface of large clusters. We have released an efficient, user-friendly, and free program "ABCluster" to realize the ABC algorithm. It is a black-box program for non-experts as well as experts and might become a useful tool for chemists to study clusters.

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.

NMR and computational study of Ba{sub 8}Cu{sub x}Ge{sub 46-x} clathrate semiconductors

Energy Technology Data Exchange (ETDEWEB)

Chen, Jing-Han, E-mail: jhchen@tamu.edu; Sirusi Arvij, Ali; Zheng, Xiang; Rodriguez, Sergio Y.; Ross, Joseph H.

2014-04-01

Highlights: • Quadrupole NMR with first-principles calculations probes local site preferences. • Cu/Ge ratio is clarified vs. the ideal Zintl composition. • Modified Becke–Johnson exchange potential agrees well with NMR Knight shifts. - Abstract: Ba{sub 8}Cu{sub x}Ge{sub 46-x} is a type-I clathrate material that forms as a semiconductor in a narrow composition range corresponding to the electron-balanced Zintl composition, with x = 5.3. We use NMR spectroscopy combined with ab initio electronic structure calculations to probe the electronic and structural behavior of these materials. Computational results based on a superstructure model for the atomic configuration of the alloy provide good agreement with the electric quadrupole-broadened NMR lineshapes. Modeling using the modified Becke–Johnson (TB-mBJ) exchange potential is also shown to agree well with experimental NMR Knight shifts. The results indicate that the Cu–Ge balance is the main factor determining the carrier density, within a narrow stability range near the ideal Zintl composition.

NMR and computational study of Ba8CuxGe46-x clathrate semiconductors

International Nuclear Information System (INIS)

Chen, Jing-Han; Sirusi Arvij, Ali; Zheng, Xiang; Rodriguez, Sergio Y.; Ross, Joseph H.

2014-01-01

Highlights: • Quadrupole NMR with first-principles calculations probes local site preferences. • Cu/Ge ratio is clarified vs. the ideal Zintl composition. • Modified Becke–Johnson exchange potential agrees well with NMR Knight shifts. - Abstract: Ba 8 Cu x Ge 46-x is a type-I clathrate material that forms as a semiconductor in a narrow composition range corresponding to the electron-balanced Zintl composition, with x = 5.3. We use NMR spectroscopy combined with ab initio electronic structure calculations to probe the electronic and structural behavior of these materials. Computational results based on a superstructure model for the atomic configuration of the alloy provide good agreement with the electric quadrupole-broadened NMR lineshapes. Modeling using the modified Becke–Johnson (TB-mBJ) exchange potential is also shown to agree well with experimental NMR Knight shifts. The results indicate that the Cu–Ge balance is the main factor determining the carrier density, within a narrow stability range near the ideal Zintl composition

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.

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

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.)

Final Project Report for ER15351 ''A Study of New Actinide Zintl Ions Materials''

International Nuclear Information System (INIS)

Peter K. Dorhout

2007-01-01

The structural chemistry of actinide main-group metal materials provides the fundamental basis for the understanding of structural coordination chemistry and the formation of materials with desired or predicted structural features. The main-group metal building blocks, comprising sulfur-group, phosphorus-group, or silicon-group elements, have shown versatility in oxidation state, coordination, and bonding preferences. These building blocks have allowed us to elucidate a series of structures that are unique to the actinide elements, although we can find structural relationships to transition metal and 4f-element materials. In the past year, we investigated controlled metathesis and self-propagating reactions between actinide metal halides and alkali metal salts of main-group metal chalcogenides such as K-P-S salts. Ternary plutonium thiophosphates have resulted from these reactions at low temperature in sealed ampules. we have also focused efforts to examine reactions of Th, U, and Pu halide salts with other alkali metal salts such as Na-Ge-S and Na-Si-Se and copper chloride to identify if self-propagating reactions may be used as a viable reaction to prepare new actinide materials and we prepared a series of U and Th copper chalcogenide materials. Magnetic measurements continued to be a focus of actinide materials prepared in our laboratory. We also contributed to the XANES work at Los Alamos by preparing materials for study and for comparison with environmental samples

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 ...

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

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

Effect of deformation temperature on niobium clustering, precipitation and austenite recrystallisation in a Nb–Ti microalloyed steel

International Nuclear Information System (INIS)

Kostryzhev, Andrii G.; Al Shahrani, Abdullah; Zhu, Chen; Ringer, Simon P.; Pereloma, Elena V.

2013-01-01

The effect of deformation temperature on Nb solute clustering, precipitation and the kinetics of austenite recrystallisation were studied in a steel containing 0.081C–0.021Ti–0.064 Nb (wt%). Thermo-mechanical processing was carried out using a Gleeble 3500 simulator. The austenite microstructure was studied using a combination of optical microscopy, transmission electron microscopy, and atom probe microscopy, enabling a careful characterisation of grain size, as well as Nb-rich clustering and precipitation processes. A correlation between the austenite recrystallisation kinetics and the chemistry, size and number density of Nb-rich solute atom clusters, and NbTi(C,N) precipitates was established via the austenite deformation temperature. Specifically, we have determined thresholds for the onset of recrystallisation: for deformation levels above 75% and temperatures above 825 °C, Nb atom clusters <8 nm effectively suppressed austenite recrystallisation

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.

Nanostructured energetic materials derived from sol-gel chemistry

International Nuclear Information System (INIS)

Simpson, R L; Tillotson, T M; Hrubesh, L W; Gash, A E

2000-01-01

Initiation and detonation properties are dramatically affected by an energetic material's microstructural properties. Sol-gel chemistry allows intimacy of mixing to be controlled and dramatically improved over existing methodologies. One material goal is to create very high power energetic materials which also have high energy densities. Using sol-gel chemistry we have made a nanostructured composite energetic material. Here a solid skeleton of fuel, based on resorcinol-formaldehyde, has nanocrystalline ammonium perchlorate, the oxidizer, trapped within its pores. At optimum stoichiometry it has approximately the energy density of HMX. Transmission electron microscopy indicated no ammonium perchlorate crystallites larger than 20 nm while near-edge soft x-ray absorption microscopy showed that nitrogen was uniformly distributed, at least on the scale of less than 80 nm. Small-angle neutron scattering studies were conducted on the material. Those results were consistent with historical ones for this class of nanostructured materials. The average skeletal primary particle size was on the order of 2.7 nm, while the nanocomposite showed the growth of small 1 nm size crystals of ammonium perchlorate with some clustering to form particles greater than 10 nm

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)

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)

Workshop report on large-scale matrix diagonalization methods in chemistry theory institute

Energy Technology Data Exchange (ETDEWEB)

Bischof, C.H.; Shepard, R.L.; Huss-Lederman, S. [eds.

1996-10-01

The Large-Scale Matrix Diagonalization Methods in Chemistry theory institute brought together 41 computational chemists and numerical analysts. The goal was to understand the needs of the computational chemistry community in problems that utilize matrix diagonalization techniques. This was accomplished by reviewing the current state of the art and looking toward future directions in matrix diagonalization techniques. This institute occurred about 20 years after a related meeting of similar size. During those 20 years the Davidson method continued to dominate the problem of finding a few extremal eigenvalues for many computational chemistry problems. Work on non-diagonally dominant and non-Hermitian problems as well as parallel computing has also brought new methods to bear. The changes and similarities in problems and methods over the past two decades offered an interesting viewpoint for the success in this area. One important area covered by the talks was overviews of the source and nature of the chemistry problems. The numerical analysts were uniformly grateful for the efforts to convey a better understanding of the problems and issues faced in computational chemistry. An important outcome was an understanding of the wide range of eigenproblems encountered in computational chemistry. The workshop covered problems involving self- consistent-field (SCF), configuration interaction (CI), intramolecular vibrational relaxation (IVR), and scattering problems. In atomic structure calculations using the Hartree-Fock method (SCF), the symmetric matrices can range from order hundreds to thousands. These matrices often include large clusters of eigenvalues which can be as much as 25% of the spectrum. However, if Cl methods are also used, the matrix size can be between 10{sup 4} and 10{sup 9} where only one or a few extremal eigenvalues and eigenvectors are needed. Working with very large matrices has lead to the development of

Are clusters important in understanding the mechanisms in atmospheric pressure ionization? Part 1: Reagent ion generation and chemical control of ion populations.

Science.gov (United States)

Klee, Sonja; Derpmann, Valerie; Wißdorf, Walter; Klopotowski, Sebastian; Kersten, Hendrik; Brockmann, Klaus J; Benter, Thorsten; Albrecht, Sascha; Bruins, Andries P; Dousty, Faezeh; Kauppila, Tiina J; Kostiainen, Risto; O'Brien, Rob; Robb, Damon B; Syage, Jack A

2014-08-01

It is well documented since the early days of the development of atmospheric pressure ionization methods, which operate in the gas phase, that cluster ions are ubiquitous. This holds true for atmospheric pressure chemical ionization, as well as for more recent techniques, such as atmospheric pressure photoionization, direct analysis in real time, and many more. In fact, it is well established that cluster ions are the primary carriers of the net charge generated. Nevertheless, cluster ion chemistry has only been sporadically included in the numerous proposed ionization mechanisms leading to charged target analytes, which are often protonated molecules. This paper series, consisting of two parts, attempts to highlight the role of cluster ion chemistry with regard to the generation of analyte ions. In addition, the impact of the changing reaction matrix and the non-thermal collisions of ions en route from the atmospheric pressure ion source to the high vacuum analyzer region are discussed. This work addresses such issues as extent of protonation versus deuteration, the extent of analyte fragmentation, as well as highly variable ionization efficiencies, among others. In Part 1, the nature of the reagent ion generation is examined, as well as the extent of thermodynamic versus kinetic control of the resulting ion population entering the analyzer region.

Physical Chemistry '98: Fourth International Conference on Fundamental and Applied Aspects of Physical Chemistry - Papers

International Nuclear Information System (INIS)

Ribnikar, S.; Anic, S.

1998-01-01

The proceedings has following chapters: Plenary lectures; Chemical Thermodynamics; Spectroscopy, Molecular Structures, Physical Chemistry of Plasma; Kinetics, Catalysis, Nonlinear Dynamics; Electrochemistry; Biophysical Chemistry, Photochemistry, Radiation Chemistry; Radiochemistry, Nuclear Chemistry; Solid State Physical Chemistry, Material Science; Macromolecular Physical Chemistry; Environmental Protection; Phase Boundaries; Complex Compounds; General Physical Chemistry. A separated abstract was prepared for each of the 20 papers selected from the three chapters: Biophysical Chemistry, Photochemistry, Radiation Chemistry; Radiochemistry, Nuclear Chemistry. and Environmental Protection. Refs and figs

Chemistry and the iron - only hydrogenase

International Nuclear Information System (INIS)

Tard, C.; Razavet, M.; Liu, X.; Ibrahim, S.; Pickett, Ch.

2005-01-01

Complete text of publication follows: Chemistry related to the hydrogenases is developing very rapidly and providing some informative insights into how the biological systems might function. Although still very much at a blue skies stage, there is some prospect for the design of artificial assemblies, materials and devices with technological application for hydrogen production/uptake provided robust system can be designed with low over potentials for hydrogen/proton interconversion (1). The iron-only hydrogenase possesses a peculiar di-iron unit coordinated by CO and CN, ligands which are normally associated with poisoning biological function. This sub-site unit is attached to a [4Fe4S] cubane center to form the catalytic site of the hydrogenase which is known as the 'H-cluster'. The synthesis of artificial sub-sites will first be described together with how their structures, spectroscopy and reactivity provides some key insights into the natural system viz. unprecedented bridging carbonyl and Fe(I) motifs in biology (2-4). How we have approached putting together the entire iron-sulfur framework of the H-cluster will then be described together with its electron-transfer and electrocatalytic properties (4). Finally, I will describe some early work on how we are beginning to incorporate structural motifs of the active-site into conducting polymer matrices, how they function as (albeit poor) electrocatalysts for hydrogen evolution, and where we see the way ahead. (1)The Chemistry and the Hydrogenases. D.J. Evans and C.J. Pickett, Chem. Soc. Rev., 32, 268-275, 2003; (2)Electron-Transfer at a Di-thiolate-Bridged Di-Iron Assembly; Electrocatalytic Hydrogen Evolution. S.J. Borg, T. Behrsing and S.P. Best, M. Ravazet, X. Liu and C.J. Pickett, J Amer. Chem. Soc., 2004, 126, 509-533; (3) Dissecting the intimate mechanism of cyanation of [Fe2S3] complexes related to the active site of all-iron hydrogenases by DFT analysis of energetics, transition states, intermediates and

Radiation chemistry

Energy Technology Data Exchange (ETDEWEB)

None

1973-07-01

Research progress is reported on radiation chemistry of heavy elements that includes the following topics: radiation chemistry of plutonium in nitric acid solutions (spectrophotometric analysis and gamma radiolysis of Pu(IV) and Pu(VI) in nitric acid solution); EPR studies of intermediates formed in radiolytic reactions with aqueous medium; two-phase radiolysis and its effect on the distribution coefficient of plutonium; and radiation chemistry of nitric acid. (DHM)

Different Approaches for the Calculation of Electronic Excited States of Nonstoichiometric Alkali Halide Clusters: The Example of Na3F

Czech Academy of Sciences Publication Activity Database

Durand, G.; Heitz, M. C.; Spiegelman, F.; Meier, C.; Mitrić, R.; Bonačić-Koutecký, V.; Pittner, Jiří

2004-01-01

Roč. 121, č. 20 (2004), s. 9898-9905 ISSN 0021-9606 R&D Projects: GA AV ČR KSK4040110 Keywords : Wigner distribution approach * optical response properties * sodium - fluoride clusters Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.105, year: 2004

Environmental chemistry. Seventh edition

Energy Technology Data Exchange (ETDEWEB)

Manahan, S.E. [Univ. of Missouri, Columbia, MO (United States)

1999-11-01

This book presents a basic understanding of environmental chemistry and its applications. In addition to providing updated materials in this field, the book emphasizes the major concepts essential to the practice of environmental chemistry. Topics of discussion include the following: toxicological chemistry; toxicological chemistry of chemical substances; chemical analysis of water and wastewater; chemical analysis of wastes and solids; air and gas analysis; chemical analysis of biological materials and xenobiotics; fundamentals of chemistry; and fundamentals of organic chemistry.

The performance of low-cost commercial cloud computing as an alternative in computational chemistry.

Science.gov (United States)

Thackston, Russell; Fortenberry, Ryan C

2015-05-05

The growth of commercial cloud computing (CCC) as a viable means of computational infrastructure is largely unexplored for the purposes of quantum chemistry. In this work, the PSI4 suite of computational chemistry programs is installed on five different types of Amazon World Services CCC platforms. The performance for a set of electronically excited state single-point energies is compared between these CCC platforms and typical, "in-house" physical machines. Further considerations are made for the number of cores or virtual CPUs (vCPUs, for the CCC platforms), but no considerations are made for full parallelization of the program (even though parallelization of the BLAS library is implemented), complete high-performance computing cluster utilization, or steal time. Even with this most pessimistic view of the computations, CCC resources are shown to be more cost effective for significant numbers of typical quantum chemistry computations. Large numbers of large computations are still best utilized by more traditional means, but smaller-scale research may be more effectively undertaken through CCC services. © 2015 Wiley Periodicals, Inc.

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.

More Chemistry with Light! More Light in Chemistry!

Science.gov (United States)

Bach, Thorsten

2015-09-21

"…︁ Why is chemistry overlooked when talking about light? Is the photon a physical particle per se? Are all important light-induced processes biological? Maybe the role of light for chemistry and the role of chemistry for light may be far less important than a few eccentric scientists would like to believe. From the perspective of a synthetically oriented photochemist, however, the facts are different …︁" Read more in the Editorial by Thorsten Bach. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Medicinal Chemistry/Pharmacology in Sophomore Organic Chemistry.

Science.gov (United States)

Harrison, Aline M.

1989-01-01

Discussed is a series of lectures designed to illustrate the use of general organic chemical principles in molecular biology, introduce current research in interdisciplinary areas to the beginner, increase interest in organic chemistry, and bridge the gap between traditional organic chemistry, biology, and the consumer. An outline is presented.…

Parallel variable selection of molecular dynamics clusters as a tool for calculation of spectroscopic properties

Czech Academy of Sciences Publication Activity Database

Kessler, Jiří; Dračínský, Martin; Bouř, Petr

2013-01-01

Roč. 34, č. 5 (2013), s. 366-371 ISSN 0192-8651 R&D Projects: GA ČR GAP208/11/0105; GA MŠk(CZ) LH11033 Grant - others:GA MŠk(CZ) LM2010005 Institutional support: RVO:61388963 Keywords : molecular dynamics * clusters * density functional theory * Raman optical activity * NMR Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.601, year: 2013

Power plant cycle chemistry - a currently neglected power plant chemistry discipline

International Nuclear Information System (INIS)

Bursik, A.

2005-01-01

Power plant cycle chemistry seems to be a stepchild at both utilities and universities and research organizations. It is felt that other power plant chemistry disciplines are more important. The last International Power Cycle Chemistry Conference in Prague may be cited as an example. A critical review of the papers presented at this conference seems to confirm the above-mentioned statements. This situation is very unsatisfactory and has led to an increasing number of component failures and instances of damage to major cycle components. Optimization of cycle chemistry in fossil power plants undoubtedly results in clear benefits and savings with respect to operating costs. It should be kept in mind that many seemingly important chemistry-related issues lose their importance during forced outages of units practicing faulty plant cycle chemistry. (orig.)

Chemistry

International Nuclear Information System (INIS)

Ferris, L.M.

1975-01-01

The chemical research and development efforts related to the design and ultimate operation of molten-salt breeder reactor systems are concentrated on fuel- and coolant-salt chemistry, including the development of analytical methods for use in these systems. The chemistry of tellurium in fuel salt is being studied to help elucidate the role of this element in the intergranular cracking of Hastelloy N. Studies were continued of the effect of oxygen-containing species on the equilibrium between dissolved UF 3 and dissolved UF 4 , and, in some cases, between the dissolved uranium fluorides and graphite, and the UC 2 . Several aspects of coolant-salt chemistry are under investigation. Hydroxy and oxy compounds that could be formed in molten NaBF 4 are being synthesized and characterized. Studies of the chemistry of chromium (III) compounds in fluoroborate melts were continued as part of a systematic investigation of the corrosion of structural alloys by coolant salt. An in-line voltammetric method for determining U 4+ /U 3+ ratios in fuel salt was tested in a forced-convection loop over a six-month period. (LK)

From trace chemistry to single atom chemistry

International Nuclear Information System (INIS)

Adloff, J.P.

1993-01-01

Hot atom chemistry in the vast majority of experimental works deals with the trace amount of radioactive matters. Accordingly, the concept of trace chemistry is at the heart of hot atom chemistry. Some aspects of the chemistry at trace scale and at subtrace scale are presented together with the related problems of speciation and the complication which may arise due to the formation of radio colloids. The examples of 127 I(n,γ) 128 I and 132 Te (β - ) 132 I are shown, and the method based on radioactivity was used. The procedure of separating the elements in pitchblende is shown as the example of the chemistry of traces. 13 27 Al+ 2 4 He→ 0 1 n+ 15 30 P and 15 30 P→ 14 30 Si+e + +V are shown, and how to recognize the presence of radioactive colloids is explained. The formation of radiocolloids is by the sorption of a trace radioelement on pre-existing colloidal impurity or the self-condensation of monomeric species. The temporal parameters of the nature of reactions at trace concentration are listed. The examples of Class A and Class B reactions are shown. The kinetics of reactions at trace level, radon concentration, anthropogenic Pu and natural Pu in environment, the behavior of Pu atoms and so on are described. (K.I.)

Organic chemistry

International Nuclear Information System (INIS)

2003-08-01

This book with sixteen chapter explains organic chemistry on linkage isomerism such as alkane, cycloalkane, alkene, aromatic compounds, stereo selective isomerization, aromatic compounds, stereo selective isomerization, organic compounds, stereo selective isomerization, organic halogen compound, alcohol, ether, aldehyde and ketone, carboxylic acid, dicarboxylic acid, fat and detergent, amino, carbohydrate, amino acid and protein, nucleotide and nucleic acid and spectroscopy, a polymer and medical chemistry. Each chapter has introduction structure and characteristic and using of organic chemistry.

Preparative radiation chemistry

International Nuclear Information System (INIS)

Drawe, H.

1978-01-01

Preparative synthesis of compounds with the aid of radiation chemistry is increasingly used in laboratories as well as on a technical scale. A large number of new compounds has been produced with the methods of radiation chemistry. With the increasing number of available radiation sources, also the number of synthesis metods in radiation chemistry has increased. This paper can only briefly mention the many possible ways of synthesis in radiation chemistry. (orig./HK) [de

KEEFEKTIFAN INKUIRI TERBIMBING BERORIENTASI GREEN CHEMISTRY TERHADAP KETERAMPILAN PROSES SAINS

Directory of Open Access Journals (Sweden)

Nur Amalia Afiyanti

2015-11-01

Full Text Available This research aims to know the effectiveness of guided inquiry oriented green chemistry for science process skills at XI school grade of SMA in Semarang on 2012/2013 period. The population is normal and homogeneous, so to take two groups of samples using cluster random sampling techniques. Design of this research is posttest only control design. The succes of this research seen from cognitive aspect of student achievement reach KKM. At the final stage of the analysis, the t test used was left-test with t count > t table (1.696. The student achievement for experimental classes obtained t count of 3.860 while the control class 0,914. This suggests that the experimental class has achieved mastery learning, while the control class not yet. The average value of the psychomotor aspects of students in the experimental class was 82.6 which is included in the excellent category and control class was 74 included in good category. In the aspect of Students environmental concern, the average value of the experimental class was 88.65 included in the excellent category and class control was 81.7 included in good category. The conclusion was that the research-oriented guided inquiry of green chemistry proved effectively increase the science process skills.Keywords: Green Chemistry, Guided Inquiry, Science Process Skills

The N2O activation by Rh5 clusters. A quantum chemistry study.

Science.gov (United States)

Olvera-Neria, Oscar; Avilés, Roberto; Francisco-Rodríguez, Héctor; Bertin, Virineya; García-Cruz, Raúl; González-Torres, Julio César; Poulain, Enrique

2015-04-01

Nitrous oxide (N2O) is a by-product of exhaust pipe gases treatment produced by motor vehicles. Therefore, the N2O reduction to N2 is necessary to meet the actual environmental legislation. The N2O adsorption and dissociation assisted by the square-based pyramidal Rh5 cluster was investigated using the density functional theory and the zero-order regular approximation (ZORA). The Rh5 sextet ground state is the most active in N2O dissociation, though the quartet and octet states are also active because they are degenerate. The Rh5 cluster spontaneously activates the N2─O cleavage, and the reaction is highly exothermic ca. -75 kcal mol(-1). The N2─O breaking is obtained for the geometrical arrangement that maximizes the overlap and electron transfers between the N2O and Rh5 frontier orbitals. The Rh5 high activity is due to the Rh 3d orbitals are located between the N2O HOMO and LUMO orbitals, which makes possible the interactions between them. In particular, the O 2p states strongly interact with Rh 3d orbitals, which finally weaken the N2─O bond. The electron transfer is from the Rh5 HOMO orbital to the N2O antibonding orbital.

Exploring the Potential of Different-Sized Supported Subnanometer Pt Clusters as Catalysts for Wet Chemical Applications

KAUST Repository

Rondelli, Manuel

2017-05-10

The use of physicochemical preparation techniques of metal clusters in the ultrahigh vacuum (UHV) allows for high control of cluster nuclearity and size distribution for fundamental studies in catalysis. Surprisingly, the potential of these systems as catalysts for organic chemistry transformations in solution has not been explored. To this end, single Pt atoms and Pt clusters with two narrow size distributions were prepared in the UHV and applied for the hydrogenation of p-chloronitrobenzene to p-chloroaniline in ethanol. Following the observation of very high catalytic turnovers (approaching the million molecules of p-nitroaniline formed per Pt cluster) and of size-dependent activity, this work addresses fundamental questions with respect to the suitability of these systems as heterogeneous catalysts for the conversion of solution-phase reagents. For this purpose, we employ scanning transmission electron microscopy (STEM) and X-ray photoelectron spectroscopy (XPS) characterization before and after reaction to assess the stability of the clusters on the support and the question of heterogeneity versus homogeneity in the catalytic process.

Influence of the photothermal effect of a gold nanorod cluster on biofilm disinfection

International Nuclear Information System (INIS)

Jo, Wonjin; Kim, Min Jun

2013-01-01

We evaluate a method for biofilm disinfection by raising biofilm temperature using the photothermal effect of a gold nanorod cluster. Gold nanorods (GNRs) are capable of generating enough heat to lyse bacteria by heating biofilm via laser irradiation. To test this, GNRs are synthesized using wet chemistry and a single GNR cluster is fabricated using photo-lithography technique. The GNR cluster is directly applied to the biofilm and its effects on bacteria are measured before and after laser irradiation. The photothermal effect of GNRs on the biofilm structure results in a considerable reduction of cell viability and biofilm thickness. Several quantitative measurements of bacterial mortality and biofilm destruction show an increase in efficacy with increasing durations of laser irradiation. Scanning electron microscopy images of the irradiated bacteria show obvious morphological damage such as rupture or collapse of the bacterial cell membrane in the biofilm. These results indicate that GNRs are useful and a potential material for use in photothermal treatments, particularly biofilm disinfection. (paper)

Organic chemistry experiment

International Nuclear Information System (INIS)

Mun, Seok Sik

2005-02-01

This book deals with organic chemistry experiments, it is divided five chapters, which have introduction, the way to write the experiment report and safety in the laboratory, basic experiment technic like recrystallization and extraction, a lot of organic chemistry experiments such as fischer esterification, ester hydrolysis, electrophilic aromatic substitution, aldol reaction, benzoin condensation, wittig reaction grignard reaction, epoxidation reaction and selective reduction. The last chapter introduces chemistry site on the internet and way to find out reference on chemistry.

The latest general chemistry

International Nuclear Information System (INIS)

Ryu, Geun Bae; Choi, Se Yeong; Kim, Chin Yeong; Yoon, Gil Jung; Lee, Eun Seok; Seo, Moon Gyu

1995-02-01

This book deals with the latest general chemistry, which is comprised of twenty-three chapters, the contents of this book are introduction, theory of atoms and molecule, chemical formula and a chemical reaction formula, structure of atoms, nature of atoms and the periodic table, structure of molecule and spectrum, gas, solution, solid, chemical combination, chemical reaction speed, chemical equilibrium, thermal chemistry, oxidation-reduction, electrochemistry, acid-base, complex, aquatic chemistry, air chemistry, nuclear chemistry, metal and nonmetal, organic chemistry and biochemistry. It has exercise in the end of each chapter.

Analytical chemistry instrumentation

International Nuclear Information System (INIS)

Laing, W.R.

1986-01-01

In nine sections, 48 chapters cover 1) analytical chemistry and the environment 2) environmental radiochemistry 3) automated instrumentation 4) advances in analytical mass spectrometry 5) fourier transform spectroscopy 6) analytical chemistry of plutonium 7) nuclear analytical chemistry 8) chemometrics and 9) nuclear fuel technology

Is Chemistry Attractive for Pupils? Czech Pupils' Perception of Chemistry

Science.gov (United States)

Kubiatko, Milan

2015-01-01

Chemistry is an important subject due to understanding the composition and structure of the things around us. The main aim of the study was to find out the perception of chemistry by lower secondary school pupils. The partial aims were to find out the influence of gender, year of study and favorite subject on the perception of chemistry. The…

Applying the Coupled-Cluster Ansatz to Solids and Surfaces in the Thermodynamic Limit

Science.gov (United States)

Gruber, Thomas; Liao, Ke; Tsatsoulis, Theodoros; Hummel, Felix; Grüneis, Andreas

2018-04-01

Modern electronic structure theories can predict and simulate a wealth of phenomena in surface science and solid-state physics. In order to allow for a direct comparison with experiment, such ab initio predictions have to be made in the thermodynamic limit, substantially increasing the computational cost of many-electron wave-function theories. Here, we present a method that achieves thermodynamic limit results for solids and surfaces using the "gold standard" coupled cluster ansatz of quantum chemistry with unprecedented efficiency. We study the energy difference between carbon diamond and graphite crystals, adsorption energies of water on h -BN, as well as the cohesive energy of the Ne solid, demonstrating the increased efficiency and accuracy of coupled cluster theory for solids and surfaces.

Brightest Cluster Galaxies in REXCESS Clusters

Science.gov (United States)

Haarsma, Deborah B.; Leisman, L.; Bruch, S.; Donahue, M.

2009-01-01

Most galaxy clusters contain a Brightest Cluster Galaxy (BCG) which is larger than the other cluster ellipticals and has a more extended profile. In the hierarchical model, the BCG forms through many galaxy mergers in the crowded center of the cluster, and thus its properties give insight into the assembly of the cluster as a whole. In this project, we are working with the Representative XMM-Newton Cluster Structure Survey (REXCESS) team (Boehringer et al 2007) to study BCGs in 33 X-ray luminous galaxy clusters, 0.055 < z < 0.183. We are imaging the BCGs in R band at the Southern Observatory for Astrophysical Research (SOAR) in Chile. In this poster, we discuss our methods and give preliminary measurements of the BCG magnitudes, morphology, and stellar mass. We compare these BCG properties with the properties of their host clusters, particularly of the X-ray emitting gas.

Towards "Bildung"-Oriented Chemistry Education

Science.gov (United States)

Sjöström, Jesper

2013-01-01

This paper concerns "Bildung"-oriented chemistry education, based on a reflective and critical discourse of chemistry. It is contrasted with the dominant type of chemistry education, based on the mainstream discourse of chemistry. "Bildung"-oriented chemistry education includes not only content knowledge in chemistry, but also…

Antimicrobial photodynamic activity and cytocompatibility of Au25(Capt18 clusters photoexcited by blue LED light irradiation

Directory of Open Access Journals (Sweden)

Miyata S

2017-04-01

Full Text Available Saori Miyata,1 Hirofumi Miyaji,1 Hideya Kawasaki,2 Masaki Yamamoto,2 Erika Nishida,1 Hiroko Takita,3 Tsukasa Akasaka,4 Natsumi Ushijima,3 Toshihiko Iwanaga,5 Tsutomu Sugaya1 1Department of Periodontology and Endodontology, Hokkaido University Graduate School of Dental Medicine, Kita-ku, Sapporo, 2Department of Chemistry and Materials Engineering, Faculty of Chemistry, Materials and Bioengineering, Kansai University, Suita-shi, Osaka, 3Support Section for Education and Research, Hokkaido University Graduate School of Dental Medicine, 4Department of Biomedical, Dental Materials and Engineering, Graduate School of Dental Medicine, Hokkaido University, 5Department of Anatomy, Laboratory of Histology and Cytology, Hokkaido University Graduate School of Medicine, Kita-ku, Sapporo, Japan Abstract: Antimicrobial photodynamic therapy (aPDT has beneficial effects in dental treatment. We applied captopril-protected gold (Au25(Capt18 clusters as a novel photosensitizer for aPDT. Photoexcited Au clusters under light irradiation generated singlet oxygen (1O2. Accordingly, the antimicrobial and cytotoxic effects of Au25(Capt18 clusters under dental blue light-emitting diode (LED irradiation were evaluated. 1O2 generation of Au25(Capt18 clusters under blue LED irradiation (420–460 nm was detected by a methotrexate (MTX probe. The antimicrobial effects of photoexcited Au clusters (0, 5, 50, and 500 µg/mL on oral bacterial cells, such as Streptococcus mutans, Aggregatibacter actinomycetemcomitans, and Porphyromonas gingivalis, were assessed by morphological observations and bacterial growth experiments. Cytotoxicity testing of Au clusters and blue LED irradiation was then performed against NIH3T3 and MC3T3-E1 cells. In addition, the biological performance of Au clusters (500 µg/mL was compared to an organic dye photosensitizer, methylene blue (MB; 10 and 100 µg/mL. We confirmed the 1O2 generation ability of Au25(Capt18 clusters through the fluorescence

Green Chemistry Metrics with Special Reference to Green Analytical Chemistry

Directory of Open Access Journals (Sweden)

Marek Tobiszewski

2015-06-01

Full Text Available The concept of green chemistry is widely recognized in chemical laboratories. To properly measure an environmental impact of chemical processes, dedicated assessment tools are required. This paper summarizes the current state of knowledge in the field of development of green chemistry and green analytical chemistry metrics. The diverse methods used for evaluation of the greenness of organic synthesis, such as eco-footprint, E-Factor, EATOS, and Eco-Scale are described. Both the well-established and recently developed green analytical chemistry metrics, including NEMI labeling and analytical Eco-scale, are presented. Additionally, this paper focuses on the possibility of the use of multivariate statistics in evaluation of environmental impact of analytical procedures. All the above metrics are compared and discussed in terms of their advantages and disadvantages. The current needs and future perspectives in green chemistry metrics are also discussed.

Green Chemistry Metrics with Special Reference to Green Analytical Chemistry.

Science.gov (United States)

Tobiszewski, Marek; Marć, Mariusz; Gałuszka, Agnieszka; Namieśnik, Jacek

2015-06-12

The concept of green chemistry is widely recognized in chemical laboratories. To properly measure an environmental impact of chemical processes, dedicated assessment tools are required. This paper summarizes the current state of knowledge in the field of development of green chemistry and green analytical chemistry metrics. The diverse methods used for evaluation of the greenness of organic synthesis, such as eco-footprint, E-Factor, EATOS, and Eco-Scale are described. Both the well-established and recently developed green analytical chemistry metrics, including NEMI labeling and analytical Eco-scale, are presented. Additionally, this paper focuses on the possibility of the use of multivariate statistics in evaluation of environmental impact of analytical procedures. All the above metrics are compared and discussed in terms of their advantages and disadvantages. The current needs and future perspectives in green chemistry metrics are also discussed.

antiSMASH 4.0-improvements in chemistry prediction and gene cluster boundary identification

DEFF Research Database (Denmark)

Blin, Kai; Wolf, Thomas; Chevrette, Marc G.

2017-01-01

Many antibiotics, chemotherapeutics, crop protection agents and food preservatives originate from molecules produced by bacteria, fungi or plants. In recent years, genome mining methodologies have been widely adopted to identify and characterize the biosynthetic gene clusters encoding...... the production of such compounds. Since 2011, the 'antibiotics and secondary metabolite analysis shell-antiSMASH' has assisted researchers in efficiently performing this, both as a web server and a standalone tool. Here, we present the thoroughly updated antiSMASH version 4, which adds several novel features...

Tracking chemistry self-efficacy and achievement in a preparatory chemistry course

Science.gov (United States)

Garcia, Carmen Alicia

Self-efficacy is a person's own perception about performing a task with a certain level of proficiency (Bandura, 1986). An important affective aspect of learning chemistry is chemistry self-efficacy (CSE). Several researchers have found chemistry self-efficacy to be a fair predictor of achievement in chemistry. This study was done in a college preparatory chemistry class for science majors exploring chemistry self-efficacy and its change as it relates to achievement. A subscale of CAEQ, Chemistry Attitudes and Experiences Questionnaire (developed by Dalgety et al, 2003) as well as student interviews were used to determine student chemistry self-efficacy as it changed during the course. The questionnaire was given to the students five times during the semester: in the first class and the class before each the four tests taken through the semester. Twenty-six students, both men and women, of the four major races/ethnicities were interviewed three times during the semester and events that triggered changes in CSE were followed through the interviews. HLM (hierarchical linear modeling) was used to model the results of the CSE surveys. Among the findings, women who started at significantly lower CSE than men accomplished a significant gain by the end of the semester. Blacks' CSE trends through the semester were found to be significantly different from the rest of the ethnicities.

Green Chemistry Pedagogy

Science.gov (United States)

Kolopajlo, Larry

2017-02-01

This chapter attempts to show how the practice of chemistry teaching and learning is enriched by the incorporation of green chemistry (GC) into lectures and labs. To support this viewpoint, evidence from a wide range of published papers serve as a cogent argument that GC attracts and engages both science and nonscience students, enhances chemistry content knowledge, and improves the image of the field, while preparing the world for a sustainable future. Published pedagogy associated with green and sustainable chemistry is critically reviewed and discussed.

Transuranic Computational Chemistry.

Science.gov (United States)

Kaltsoyannis, Nikolas

2018-02-26

Recent developments in the chemistry of the transuranic elements are surveyed, with particular emphasis on computational contributions. Examples are drawn from molecular coordination and organometallic chemistry, and from the study of extended solid systems. The role of the metal valence orbitals in covalent bonding is a particular focus, especially the consequences of the stabilization of the 5f orbitals as the actinide series is traversed. The fledgling chemistry of transuranic elements in the +II oxidation state is highlighted. Throughout, the symbiotic interplay of experimental and computational studies is emphasized; the extraordinary challenges of experimental transuranic chemistry afford computational chemistry a particularly valuable role at the frontier of the periodic table. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Cluster computing for lattice QCD simulations

International Nuclear Information System (INIS)

Coddington, P.D.; Williams, A.G.

2000-01-01

Full text: Simulations of lattice quantum chromodynamics (QCD) require enormous amounts of compute power. In the past, this has usually involved sharing time on large, expensive machines at supercomputing centres. Over the past few years, clusters of networked computers have become very popular as a low-cost alternative to traditional supercomputers. The dramatic improvements in performance (and more importantly, the ratio of price/performance) of commodity PCs, workstations, and networks have made clusters of off-the-shelf computers an attractive option for low-cost, high-performance computing. A major advantage of clusters is that since they can have any number of processors, they can be purchased using any sized budget, allowing research groups to install a cluster for their own dedicated use, and to scale up to more processors if additional funds become available. Clusters are now being built for high-energy physics simulations. Wuppertal has recently installed ALiCE, a cluster of 128 Alpha workstations running Linux, with a peak performance of 158 G flops. The Jefferson Laboratory in the US has a 16 node Alpha cluster and plans to upgrade to a 256 processor machine. In Australia, several large clusters have recently been installed. Swinburne University of Technology has a cluster of 64 Compaq Alpha workstations used for astrophysics simulations. Early this year our DHPC group constructed a cluster of 116 dual Pentium PCs (i.e. 232 processors) connected by a Fast Ethernet network, which is used by chemists at Adelaide University and Flinders University to run computational chemistry codes. The Australian National University has recently installed a similar PC cluster with 192 processors. The Centre for the Subatomic Structure of Matter (CSSM) undertakes large-scale high-energy physics calculations, mainly lattice QCD simulations. The choice of the computer and network hardware for a cluster depends on the particular applications to be run on the machine. Our

OCCAM: a flexible, multi-purpose and extendable HPC cluster

Science.gov (United States)

Aldinucci, M.; Bagnasco, S.; Lusso, S.; Pasteris, P.; Rabellino, S.; Vallero, S.

2017-10-01

The Open Computing Cluster for Advanced data Manipulation (OCCAM) is a multipurpose flexible HPC cluster designed and operated by a collaboration between the University of Torino and the Sezione di Torino of the Istituto Nazionale di Fisica Nucleare. It is aimed at providing a flexible, reconfigurable and extendable infrastructure to cater to a wide range of different scientific computing use cases, including ones from solid-state chemistry, high-energy physics, computer science, big data analytics, computational biology, genomics and many others. Furthermore, it will serve as a platform for R&D activities on computational technologies themselves, with topics ranging from GPU acceleration to Cloud Computing technologies. A heterogeneous and reconfigurable system like this poses a number of challenges related to the frequency at which heterogeneous hardware resources might change their availability and shareability status, which in turn affect methods and means to allocate, manage, optimize, bill, monitor VMs, containers, virtual farms, jobs, interactive bare-metal sessions, etc. This work describes some of the use cases that prompted the design and construction of the HPC cluster, its architecture and resource provisioning model, along with a first characterization of its performance by some synthetic benchmark tools and a few realistic use-case tests.

Chemistry Notes

Science.gov (United States)

School Science Review, 1976

1976-01-01

Described are eight chemistry experiments and demonstrations applicable to introductory chemistry courses. Activities include: measure of lattice enthalpy, Le Chatelier's principle, decarboxylation of soap, use of pocket calculators in pH measurement, and making nylon. (SL)

Fundamentals of nuclear chemistry

International Nuclear Information System (INIS)

Matel, L.; Dulanska, S.

2013-01-01

This text-book is an introductory text in nuclear chemistry and radiochemistry, aimed on university undergraduate students in chemistry and related disciplines (physics, nuclear engineering). It covers the key aspects of modern nuclear chemistry. The text begins with basic theories in contemporary physics. It relates nuclear phenomena to key divisions of chemistry such as atomic structure, spectroscopy, equilibria and kinetics. It also gives an introduction to sources of ionizing radiation, detection of ionizing radiation, nuclear power industry and accident on nuclear installations as well as basic knowledge's of radiobiology. This book is essential reading for those taking a first course in nuclear chemistry and is a useful companion to other volumes in physical and analytical chemistry. It will also be of use to those new to working in nuclear chemistry or radiochemistry.

Handbook of heterocyclic chemistry

National Research Council Canada - National Science Library

Katritzky, Alan R

2010-01-01

... Heterocyclic Chemistry I (1984) Comprehensive Heterocyclic Chemistry II (1996) Comprehensive Heterocyclic Chemistry III (2008) Comprehensive Organic Functional Group Transformations I (1995) Compreh...

Chemistry Dashboard

Science.gov (United States)

The Chemistry Dashboard is part of a suite of dashboards developed by EPA to help evaluate the safety of chemicals. The Chemistry Dashboard provides access to a variety of information on over 700,000 chemicals currently in use.

Silver Clusters in Zeolites: From Self-Assembly to Ground-Breaking Luminescent Properties.

Science.gov (United States)

Coutiño-Gonzalez, Eduardo; Baekelant, Wouter; Steele, Julian A; Kim, Cheol Woong; Roeffaers, Maarten B J; Hofkens, Johan

2017-09-19

Interest for functional silver clusters (Ag-CLs) has rapidly grown over years due to large advances in the field of nanoscale fabrication and materials science. The continuous development of strategies to fabricate small-scale silver clusters, together with their interesting physicochemical properties (molecule-like discrete energy levels, for example), make them very attractive for a wide variety of applied research fields, from biotechnology and the environmental sciences to fundamental chemistry and physics. Apart from useful catalytic properties, silver clusters (Ag n , n counterbalancing ions, silver loading, and zeolite topology, and cannot be overlooked. This Account is intended to shed light on the current state-of-the-art of luminescent Ag-CLs confined in zeolitic matrices, emphasizing the use of combinatorial approaches to overcome problems associated with the correct characterization and correlation of their structural, electronic, and photoluminescence properties, all to establish the important design principles for developing functional silver-zeolite-based materials. Additionally, examples of emerging applications and future perspectives for functional luminescent Ag-zeolite materials are addressed in this Account.

Materials Chemistry

CERN Document Server

Fahlman, Bradley D

2011-01-01

The 2nd edition of Materials Chemistry builds on the strengths that were recognized by a 2008 Textbook Excellence Award from the Text and Academic Authors Association (TAA). Materials Chemistry addresses inorganic-, organic-, and nano-based materials from a structure vs. property treatment, providing a suitable breadth and depth coverage of the rapidly evolving materials field. The 2nd edition continues to offer innovative coverage and practical perspective throughout. After briefly defining materials chemistry and its history, seven chapters discuss solid-state chemistry, metals, semiconducting materials, organic "soft" materials, nanomaterials, and materials characterization. All chapters have been thoroughly updated and expanded with, for example, new sections on ‘soft lithographic’ patterning, ‘click chemistry’ polymerization, nanotoxicity, graphene, as well as many biomaterials applications. The polymer and ‘soft’ materials chapter represents the largest expansion for the 2nd edition. Each ch...

Progress report, Chemistry and Materials Division

International Nuclear Information System (INIS)

1982-02-01

A marked asymmetry has been observed in the intensity of ions scattered from manganese atoms in a Mn-Al alloy as a function of incidence angle, under near-axial channeling conditions. Proton dechanneling has been used to discriminate between simple and cluster defects created by He-ion irradiation of an Al-Ag alloy crystal. An automated Langmuir surface has been constructed for study of the radiation chemistry of polyunsaturated compounds organized in molecular films. New information about reactions of nitric oxide (NO) has been obtained which suggests that the reaction of NO with O 2 in the gas phase is also an important reaction in the radiation chemistry of oxygenated nitrate and nitrite solutions. Development work on an ion-selective electrode for the determination of boron has been completed. Recent studies have resulted in improvements to the mass spectrometric determination of thorium, uranium and plutonium. Good agreement between the results of the determinations of atom percent fission by a stable isotope dilution Nd-148 and a uranium isotope ratio method was observed. Examination of a large number of iodine-induced crack initiation sites formed under conditions where the hydrides are in solution has shown no evidence for the involvement of any second phase particles, or any local segregation of impurities or alloying elements. Reproducible improvement in the purity of zirconium has been achieved by the electrotransport method. Doppler broadening studies of positron annihilation in electron irradiated Zr and Ti have been completed

Quantum chemistry

CERN Document Server

Lowe, John P

1993-01-01

Praised for its appealing writing style and clear pedagogy, Lowe's Quantum Chemistry is now available in its Second Edition as a text for senior undergraduate- and graduate-level chemistry students. The book assumes little mathematical or physical sophistication and emphasizes an understanding of the techniques and results of quantum chemistry, thus enabling students to comprehend much of the current chemical literature in which quantum chemical methods or concepts are used as tools. The book begins with a six-chapter introduction of standard one-dimensional systems, the hydrogen atom,

PREFACE: Nuclear Cluster Conference; Cluster'07

Science.gov (United States)

Freer, Martin

2008-05-01

The Cluster Conference is a long-running conference series dating back to the 1960's, the first being initiated by Wildermuth in Bochum, Germany, in 1969. The most recent meeting was held in Nara, Japan, in 2003, and in 2007 the 9th Cluster Conference was held in Stratford-upon-Avon, UK. As the name suggests the town of Stratford lies upon the River Avon, and shortly before the conference, due to unprecedented rainfall in the area (approximately 10 cm within half a day), lay in the River Avon! Stratford is the birthplace of the `Bard of Avon' William Shakespeare, and this formed an intriguing conference backdrop. The meeting was attended by some 90 delegates and the programme contained 65 70 oral presentations, and was opened by a historical perspective presented by Professor Brink (Oxford) and closed by Professor Horiuchi (RCNP) with an overview of the conference and future perspectives. In between, the conference covered aspects of clustering in exotic nuclei (both neutron and proton-rich), molecular structures in which valence neutrons are exchanged between cluster cores, condensates in nuclei, neutron-clusters, superheavy nuclei, clusters in nuclear astrophysical processes and exotic cluster decays such as 2p and ternary cluster decay. The field of nuclear clustering has become strongly influenced by the physics of radioactive beam facilities (reflected in the programme), and by the excitement that clustering may have an important impact on the structure of nuclei at the neutron drip-line. It was clear that since Nara the field had progressed substantially and that new themes had emerged and others had crystallized. Two particular topics resonated strongly condensates and nuclear molecules. These topics are thus likely to be central in the next cluster conference which will be held in 2011 in the Hungarian city of Debrechen. Martin Freer Participants and Cluster'07

Research on condensed matter and atomic physics using major experimental facilities and devices: Physics, chemistry, biology. Reports on results. Vol. 3. 4. Chemistry. 5. Biology. 6. Development of methods and instruments

International Nuclear Information System (INIS)

1993-01-01

This report in three volumes substantiates the contents of the programme survey published in September 1989. The progress reports cover the following research areas: Vol. I, (1). Atomic and molecular physics - free atoms, molecules, macromolecules, clusters, matrix-isolated atoms and molecules. (2) Physics and chemistry of surfaces and interfaces - epitaxy, surface structure, adsorption, electrical, magnetic, and optical properties, thin films, synthetic layer structure. Vol. II, (3). Solid-state physics, and materials science -structural research, lattice dynamics, magnetic structure and dynamics, electronic states; load; spin and pulse density fluctuations; diffusion and internal motion, defects, unordered systems and liquids. Vol. III, (4). Chemistry - bonding and structure, kinetics and reaction mechanisms, polymer research, analysis and synthesis. (5). Biology, - structure and dynamics of biological macromolecules, membrane and cell biology. (6) Development of methods and instruments - neutron sources, synchrotron sources, special accelerators, research with interlinked systems and devices. (orig.) [de

Thermodynamics of Small Alkali Metal Halide Cluster Ions: Comparison of Classical Molecular Simulations with Experiment and Quantum Chemistry

Czech Academy of Sciences Publication Activity Database

Vlček, L.; Uhlík, F.; Moučka, F.; Nezbeda, Ivo; Chialvo, L.

2015-01-01

Roč. 119, č. 3 (2015), s. 488-500 ISSN 1089-5639 Institutional support: RVO:67985858 Keywords : monte-carlo simulations * molecular-dynamic simulations * classical drude oscillators Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.883, year: 2015

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

Annual Report 1984. Chemistry Department

DEFF Research Database (Denmark)

Funck, Jytte; Nielsen, Ole John

This report contains a brief survey of the main activities in the Chemistry Department. All articles and reports published and lectures given in 1984 are presented. The facilities and equipment are mentioned briefly. The activities are divided into the following groups: radioisotope chemistry, an......, analytical- and organic chemistry, environmental chemistry, polymer chemistry, geochemistry and waste disposal, radical chemistry, positron annihilation, mineral processing, and general.......This report contains a brief survey of the main activities in the Chemistry Department. All articles and reports published and lectures given in 1984 are presented. The facilities and equipment are mentioned briefly. The activities are divided into the following groups: radioisotope chemistry...

Electron tunneling in chemistry

International Nuclear Information System (INIS)

Zamaraev, K.I.; Khajrutdinov, R.F.; Zhdanov, V.P.; Molin, Yu.N.

1985-01-01

Results of experimental and theoretical investigations are outlined systematically on electron tunnelling in chemical reactions. Mechanism of electron transport to great distances is shown to be characteristic to chemical compounds of a wide range. The function of tunnel reactions is discussed for various fields of chemistry, including radiation chemistry, electrochemistry, chemistry of solids, chemistry of surface and catalysis

Annual report 1984 Chemistry Department

International Nuclear Information System (INIS)

Funck, J.; Larsen, E.; Nielsen, O.J.

1985-03-01

This report contains a brief survey of the main activities in the Chemistry Department. All articles and reports published and lectures given in 1984 are presented. The facilities and equipment are mentioned briefly. The activities are divided into the following groups: radioisotope chemistry, analytical- and organic chemistry , environmental chemistry, polymer chemistry, geochemistry and waste disposal, radical chemistry, positron annihilation, mineral processing, and general. (author)

Annual report 1987 Chemistry Department

International Nuclear Information System (INIS)

Funck, J.; Larsen, E.; Nielsen, O.J.

1988-04-01

This report contains a brief survey of the main activities in the Chemistry Department. The names and abstracts of all articles and reports published and lectures given in 1987 are presented. The facilities and equipment are mentioned briefly. The activities are divided into the following groups: radioisotope chemistry, analytical- and organic chemistry, environmental chemistry, polymer chemistry, radical chemistry, mineral processing, and general. 13 ills., (author)

Annual report 1985 Chemistry Department

International Nuclear Information System (INIS)

Funck, J.; Larsen, E.; Nielsen, O.J.

1986-03-01

This report contains a brief survey of the main activities in the Chemistry Department. All particles and reports published and lectures given in 1985 are presented. The facilities and equipment are mentioned briefly. The activities are divided into the following groups: radioisotope chemistry, analytical- and organic chemistry, environmental chemistry, polymer chemistry, geochemistry and waste disposal, radical chemistry, positron annihilation, mineral processing, and general. (author)

Annual report 1982 chemistry department

International Nuclear Information System (INIS)

Larsen, E.; Nielsen, O.J.

1983-04-01

The work going on in the Risoe National Laboratory, Chemistry Department is briefly surveyed by a presentation of all articles and reports published in 1982. The facilities and equipment are barely mentioned. The papers are divided into eight activities: 1. neutron activation analysis 2. analytical- and organic chemistry 3. environmental chemistry 4. polymer chemistry 5. geochemistry 6. radical chemistry 7. poitron annihilation 8. uranium process chemistry. (author)

Beyond Academic Tracking: Using Cluster Analysis and Self-Organizing Maps to Investigate Secondary Students' Chemistry Self-Concept

Science.gov (United States)

Nielsen, Sara E.; Yezierski, Ellen J.

2016-01-01

Academic tracking, placing students in different classes based on past performance, is a common feature of the American secondary school system. A longitudinal study of secondary students' chemistry self-concept scores was conducted, and one feature of the study was the presence of academic tracking. Though academic tracking is one way to group…

Formation of stable products from cluster-cluster collisions

International Nuclear Information System (INIS)

Alamanova, Denitsa; Grigoryan, Valeri G; Springborg, Michael

2007-01-01

The formation of stable products from copper cluster-cluster collisions is investigated by using classical molecular-dynamics simulations in combination with an embedded-atom potential. The dependence of the product clusters on impact energy, relative orientation of the clusters, and size of the clusters is studied. The structures and total energies of the product clusters are analysed and compared with those of the colliding clusters before impact. These results, together with the internal temperature, are used in obtaining an increased understanding of cluster fusion processes

Atom-at-a-time chemistry

International Nuclear Information System (INIS)

Nagame, Yuichiro

2009-01-01

Several techniques of the analytical chemistry in 'Atom-at-a-time chemistry' for transactinide elements have been developed. In this report a representative example in these techniques is introduced with the results. The contents are the single-atom chemistry, the chemical experiments on transactinide elements, liquid phase chemistry (the ion exchange behavior of Rutherfordium), gas phase chemistry (the chemistry of atomic No.112 element), and future development. (M.H.)

Chemistry, Poetry, and Artistic Illustration: An Interdisciplinary Approach to Teaching and Promoting Chemistry

Science.gov (United States)

Furlan, Ping Y.; Kitson, Herbert; Andes, Cynthia

2007-10-01

This article describes a successful interdisciplinary collaboration among chemistry, humanities and English faculty members, who utilized poetry and artistic illustration to help students learn, appreciate, and enjoy chemistry. Students taking general chemistry classes were introduced to poetry writing and museum-type poster preparation during one class period. They were then encouraged to use their imagination and creativity to brainstorm and write chemistry poems or humors on the concepts and principles covered in the chemistry classes and artistically illustrate their original work on posters. The project, 2 3 months in length, was perceived by students as effective at helping them learn chemistry and express their understanding in a fun, personal, and creative way. The instructors found students listened to the directives because many posters were witty, clever, and eye-catching. They showed fresh use of language and revealed a good understanding of chemistry. The top posters were created by a mix of A-, B-, and C-level students. The fine art work, coupled with poetry, helped chemistry come alive on campus, providing an aesthetic presentation of materials that engaged the general viewer.

On the mechanism of water cluster-ion formation in carbon dioxide

International Nuclear Information System (INIS)

Warneck, P.; Rakshit, A.B.

1981-01-01

A drift chamber mass spectrometer has been used to study the formation of water cluster-ions in carbon dioxide containing traces of water vapour. The dominant reaction sequences were identified up to the fourth generation of daughter ions starting with CO 2 + . The subsequent reaction mechanism remains uncertain and several possibilities are discussed. The final ions are H 3 O + H 2 O and H 3 O + (H 2 O) 2 . The significance of the reaction schemes to the radiation chemistry of carbon dioxide is pointed out. (orig.)

USSR Report Chemistry

National Research Council Canada - National Science Library

1986-01-01

Contents: Adsorption, Chemistry,Alkaloids, Analytical Chemistry, Catalysis,Chemical Industry,,Coal Gasification, Combustion, Electrochemistry,Explosives and Explosions, Fertilizers, Free Radicals, Inorganic...

Document clustering methods, document cluster label disambiguation methods, document clustering apparatuses, and articles of manufacture

Science.gov (United States)

Sanfilippo, Antonio [Richland, WA; Calapristi, Augustin J [West Richland, WA; Crow, Vernon L [Richland, WA; Hetzler, Elizabeth G [Kennewick, WA; Turner, Alan E [Kennewick, WA

2009-12-22

Document clustering methods, document cluster label disambiguation methods, document clustering apparatuses, and articles of manufacture are described. In one aspect, a document clustering method includes providing a document set comprising a plurality of documents, providing a cluster comprising a subset of the documents of the document set, using a plurality of terms of the documents, providing a cluster label indicative of subject matter content of the documents of the cluster, wherein the cluster label comprises a plurality of word senses, and selecting one of the word senses of the cluster label.

Green Chemistry Metrics with Special Reference to Green Analytical Chemistry

OpenAIRE

Marek Tobiszewski; Mariusz Marć; Agnieszka Gałuszka; Jacek Namieśnik

2015-01-01

The concept of green chemistry is widely recognized in chemical laboratories. To properly measure an environmental impact of chemical processes, dedicated assessment tools are required. This paper summarizes the current state of knowledge in the field of development of green chemistry and green analytical chemistry metrics. The diverse methods used for evaluation of the greenness of organic synthesis, such as eco-footprint, E-Factor, EATOS, and Eco-Scale are described. Both the well-establis...

Nuclear clustering - a cluster core model study

International Nuclear Information System (INIS)

Paul Selvi, G.; Nandhini, N.; Balasubramaniam, M.

2015-01-01

Nuclear clustering, similar to other clustering phenomenon in nature is a much warranted study, since it would help us in understanding the nature of binding of the nucleons inside the nucleus, closed shell behaviour when the system is highly deformed, dynamics and structure at extremes. Several models account for the clustering phenomenon of nuclei. We present in this work, a cluster core model study of nuclear clustering in light mass nuclei

The New Color of Chemistry: Green Chemistry

OpenAIRE

Zuhal GERÇEK

2012-01-01

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 provid...

Nuclear chemistry in the traditional chemistry program

International Nuclear Information System (INIS)

Kleppinger, E.W.

1993-01-01

The traditional undergraduate program for chemistry majors, especially at institutions devoted solely to undergraduate education, has limited space for 'special topics' courses in areas such as nuclear and radiochemistry. A scheme is proposed whereby the basic topics covered in an introductury radiochemistry course are touched upon, and in some cases covered in detail, at some time during the four-year sequence of courses taken by a chemistry major. (author) 6 refs.; 7 tabs

Annual report 1986 chemistry department

International Nuclear Information System (INIS)

Funck, J.; Larsen, E.; Nielsen, O.J.

1987-03-01

This report contains a brief survey of the main activities in the Chemistry Department. All articles and reports published and lectures given in 1986 are presented. The facilities and equipment are mentioned briefly. The activities are divided into the following groups: radioisotope chemistry, analytical- and organic chemistry, environmental chemistry, polymer chemistry, radical chemistral, mineral processing, and general. (author)

Cluster fusion algorithm: application to Lennard-Jones clusters

DEFF Research Database (Denmark)

Solov'yov, Ilia; Solov'yov, Andrey V.; Greiner, Walter

2006-01-01

paths up to the cluster size of 150 atoms. We demonstrate that in this way all known global minima structures of the Lennard-Jones clusters can be found. Our method provides an efficient tool for the calculation and analysis of atomic cluster structure. With its use we justify the magic number sequence......We present a new general theoretical framework for modelling the cluster structure and apply it to description of the Lennard-Jones clusters. Starting from the initial tetrahedral cluster configuration, adding new atoms to the system and absorbing its energy at each step, we find cluster growing...... for the clusters of noble gas atoms and compare it with experimental observations. We report the striking correspondence of the peaks in the dependence of the second derivative of the binding energy per atom on cluster size calculated for the chain of the Lennard-Jones clusters based on the icosahedral symmetry...

Cluster fusion algorithm: application to Lennard-Jones clusters

DEFF Research Database (Denmark)

Solov'yov, Ilia; Solov'yov, Andrey V.; Greiner, Walter

2008-01-01

paths up to the cluster size of 150 atoms. We demonstrate that in this way all known global minima structures of the Lennard-Jones clusters can be found. Our method provides an efficient tool for the calculation and analysis of atomic cluster structure. With its use we justify the magic number sequence......We present a new general theoretical framework for modelling the cluster structure and apply it to description of the Lennard-Jones clusters. Starting from the initial tetrahedral cluster configuration, adding new atoms to the system and absorbing its energy at each step, we find cluster growing...... for the clusters of noble gas atoms and compare it with experimental observations. We report the striking correspondence of the peaks in the dependence of the second derivative of the binding energy per atom on cluster size calculated for the chain of the Lennard-Jones clusters based on the icosahedral symmetry...

Moderator Chemistry Program

International Nuclear Information System (INIS)

Dewitt, L.V.; Gibbs, A.; Lambert, D.P.; Bohrer, S.R.; Fanning, R.L.; Houston, M.W.; Stinson, S.L.; Deible, R.W.; Abdel-Khalik, S.I.

1990-11-01

Over the past fifteen months, the Systems Chemistry Group of the Reactor Engineering Department has undertaken a comprehensive study of the Department's moderator chemistry program at Savannah River Site (SRS). An internal review was developed to formalize and document this program. Objectives were as outlined in a mission statement and action plan. In addition to the mission statement and action plan, nine separate task reports have been issued during the course of this study. Each of these task reports is included in this document as a chapter. This document is an organized compilation of the individual reports issued by the Systems Chemistry Group in assessment of SRS moderator chemistry to determine if there were significant gaps in the program as ft existed in October, 1989. While these reviews found no significant gaps in that mode of operation, or any items that adversely affected safety, items were identified that could be improved. Many of the items have already been dear with or are in the process of completion under this Moderator Chemistry Program and other Reactor Restart programs. A complete list of the items of improvement found under this assessment is found in Chapter 9, along with a proposed time table for correcting remaining items that can be improved for the chemistry program of SRS reactors. An additional external review of the moderator chemistry processes, recommendations, and responses to/from the Reactor Corrosion Mitigation Committee is included as Appendix to this compilation

Publicising chemistry in a multicultural society through chemistry outreach

Directory of Open Access Journals (Sweden)

Joyce D. Sewry

2011-11-01

Full Text Available Given the emphasis in Higher Education on community engagement in South Africa and the importance of international collaboration, we discuss a joint approach to chemistry outreach in two countries on two continents with widely differing target school audiences. We describe the history of the partnership between the chemistry departments at Rhodes University and the University of Bristol and provide an outline of the chemistry content of their outreach initiatives, the modes of delivery, the advantages to both departments and their students for involvement in various levels of outreach, the challenges they still face and additional opportunities that such work facilitated. The lecture demonstration ‘A Pollutant’s Tale’ was presented to thousands of learners all over the world, including learners at resource-deprived schools in South Africa. Challenges to extend outreach activities in South Africa include long travelling distances, as well as a lack of facilities (such as school halls and electricity at schools. Outreach activities not only impacted on the target audience of young learners, they also impacted upon the postgraduate and other chemistry students taking part in these initiatives. This collaboration strengthened both institutions and their outreach work and may also lead to chemistry research collaborations between the academics involved.

Molecular materials and devices: developing new functional systems based on the coordination chemistry approach

Directory of Open Access Journals (Sweden)

Toma Henrique E.

2003-01-01

Full Text Available At the onset of the nanotechnology age, molecular designing of materials and single molecule studies are opening wide possibilities of using molecular systems in electronic and photonic devices, as well as in technological applications based on molecular switching or molecular recognition. In this sense, inorganic chemists are privileged by the possibility of using the basic strategies of coordination chemistry to build up functional supramolecular materials, conveying the remarkable chemical properties of the metal centers and the characteristics of the ancillary ligands. Coordination chemistry also provides effective self-assembly strategies based on specific metal-ligand affinity and stereochemistry. Several molecular based materials, derived from inorganic and metal-organic compounds are focused on this article, with emphasis on new supramolecular porphyrins and porphyrazines, metal-clusters and metal-polyimine complexes. Such systems are also discussed in terms of their applications in catalysis, sensors and molecular devices.

American Association for Clinical Chemistry

Science.gov (United States)

... Find the answer to your question IN CLINICAL CHEMISTRY Hs-cTnI as a Gatekeeper for Further Cardiac ... Online Harmonization.net Commission on Accreditation in Clinical Chemistry American Board of Clinical Chemistry Clinical Chemistry Trainee ...

Proceedings of the 17. Annual Meeting of the Brazilian Chemistry Society; 7. National Symposium on Inorganic Chemistry. Abstracts

International Nuclear Information System (INIS)

1994-01-01

These 17. Annual Meeting of the Brazilian Chemistry Society and 7. National Symposium on Inorganic Chemistry present several subjects of different interests for the participants, including sections about inorganic chemistry; organic chemistry; environmental chemistry; technological chemistry; electrochemistry; physical chemistry; photochemistry; chemical education; natural products; analytical chemistry and biological chemistry. (C.G.C.)

Annual report 1988 Chemistry Department

International Nuclear Information System (INIS)

Funck, J.; Neve Larsen, Aa.; Larsen, E.; Nielsen, O.J.

1989-05-01

This report contains a brief survey of the main activities in the Chemistry Department. The names and abstracts of all articles and reports published and lectures given in 1988 are presented. The facilities and equipment are mentioned briefly. The activities are divided into the following groups: radioisotope chemistry, analytical- and organic chemistry, environmental chemistry, polymer chemistry, chemical reactivity, mineral processing, and general. (author)

Annual report 1989 Chemistry Department

International Nuclear Information System (INIS)

Funck, J.; Neve Larsen, Aa.; Larsen, E.; Nielsen, O.J.

1990-03-01

This report contains a brief survey of the main activities in the Chemistry Department. The names and abstracts of all articles and reports published and lectures given in 1989 are presented. The facilities and equipment are mentioned briefly. The activities are divided into the following groups: radioisotope chemistry, analytical- and organic chemistry, environmental chemistry, polymer chemistry, chemical reactivity, mineral processing, and general. (author)

Why Teach Environmental Chemistry?

Science.gov (United States)

Gardner, Marjorie H.

1974-01-01

Discusses the importance of teaching environmental chemistry in secondary school science classes, and outlines five examples of environmental chemistry problems that focus on major concepts of chemistry and have critical implications for human survival and well-being. (JR)

Frontiers in Gold Chemistry

OpenAIRE

Ahmed A. Mohamed

2015-01-01

Basic chemistry of gold tells us that it can bond to sulfur, phosphorous, nitrogen, and oxygen donor ligands. The Frontiers in Gold Chemistry Special Issue covers gold complexes bonded to the different donors and their fascinating applications. This issue covers both basic chemistry studies of gold complexes and their contemporary applications in medicine, materials chemistry, and optical sensors. There is a strong belief that aurophilicity plays a major role in the unending applications of g...

Advanced Chemistry Laboratory

Data.gov (United States)

Federal Laboratory Consortium — Description/History: Chemistry laboratoryThe Advanced Chemistry Laboratory (ACL) is a unique facility designed for working with the most super toxic compounds known...

Introducing Chemistry Students to the "Real World" of Chemistry

Science.gov (United States)

Brown, Michael E.; Cosser, Ronald C.; Davies-Coleman, Michael T.; Kaye, Perry T.; Klein, Rosalyn; Lamprecht, Emmanuel; Lobb, Kevin; Nyokong, Tebello; Sewry, Joyce D.; Tshentu, Zenixole R.; van der Zeyde, Tino; Watkins, Gareth M.

2010-01-01

A majority of chemistry graduates seek employment in a rapidly changing chemical industry. Our attempts to provide the graduates with skills in entrepreneurship and the ability to understand and communicate with their chemical engineering colleagues, in addition to their fundamental knowledge of chemistry, are described. This is done at…

A Titanium–Organic Framework as an Exemplar of Combining the Chemistry of Metal– and Covalent–Organic Frameworks

Energy Technology Data Exchange (ETDEWEB)

Nguyen, Ha L.; Gándara, Felipe; Furukawa, Hiroyasu; Doan, Tan L. H.; Cordova, Kyle E.; Yaghi, Omar M.

2016-04-06

A crystalline material with a two-dimensional structure, termed metal–organic framework-901 (MOF-901), was prepared using a strategy that combines the chemistry of MOFs and covalent–organic frameworks (COFs). This strategy involves in situ generation of an amine-functionalized titanium oxo cluster, Ti6O6(OCH3)6(AB)6 (AB = 4-aminobenzoate), which was linked with benzene-1,4-dialdehyde using imine condensation reactions, typical of COFs. The crystal structure of MOF-901 is composed of hexagonal porous layers that are likely stacked in staggered conformation (hxl topology). This MOF represents the first example of combining metal cluster chemistry with dynamic organic covalent bond formation to give a new crystalline, extended framework of titanium metal, which is rarely used in MOFs. The incorporation of Ti(IV) units made MOF-901 useful in the photocatalyzed polymerization of methyl methacrylate (MMA). The resulting polyMMA product was obtained with a high-number-average molar mass (26 850 g mol–1) and low polydispersity index (1.6), which in many respects are better than those achieved by the commercially available photocatalyst (P-25 TiO2). Additionally, the catalyst can be isolated, reused, and recycled with no loss in performance.

In-Package Chemistry Abstraction

Energy Technology Data Exchange (ETDEWEB)

P.S. Domski

2003-07-21

The work associated with the development of this model report was performed in accordance with the requirements established in ''Technical Work Plan for Waste Form Degradation Modeling, Testing, and Analyses in Support of SR and LA'' (BSC 2002a). The in-package chemistry model and in-package chemistry model abstraction are developed to predict the bulk chemistry inside of a failed waste package and to provide simplified expressions of that chemistry. The purpose of this work is to provide the abstraction model to the Performance Assessment Project and the Waste Form Department for development of geochemical models of the waste package interior. The scope of this model report is to describe the development and validation of the in-package chemistry model and in-package chemistry model abstraction. The in-package chemistry model will consider chemical interactions of water with the waste package materials and the waste form for commercial spent nuclear fuel (CSNF) and codisposed high-level waste glass (HLWG) and N Reactor spent fuel (CDNR). The in-package chemistry model includes two sub-models, the first a water vapor condensation (WVC) model, where water enters a waste package as vapor and forms a film on the waste package components with subsequent film reactions with the waste package materials and waste form--this is a no-flow model, the reacted fluids do not exit the waste package via advection. The second sub-model of the in-package chemistry model is the seepage dripping model (SDM), where water, water that may have seeped into the repository from the surrounding rock, enters a failed waste package and reacts with the waste package components and waste form, and then exits the waste package with no accumulation of reacted water in the waste package. Both of the submodels of the in-package chemistry model are film models in contrast to past in-package chemistry models where all of the waste package pore space was filled with water. The

In-Package Chemistry Abstraction

International Nuclear Information System (INIS)

P.S. Domski

2003-01-01

The work associated with the development of this model report was performed in accordance with the requirements established in ''Technical Work Plan for Waste Form Degradation Modeling, Testing, and Analyses in Support of SR and LA'' (BSC 2002a). The in-package chemistry model and in-package chemistry model abstraction are developed to predict the bulk chemistry inside of a failed waste package and to provide simplified expressions of that chemistry. The purpose of this work is to provide the abstraction model to the Performance Assessment Project and the Waste Form Department for development of geochemical models of the waste package interior. The scope of this model report is to describe the development and validation of the in-package chemistry model and in-package chemistry model abstraction. The in-package chemistry model will consider chemical interactions of water with the waste package materials and the waste form for commercial spent nuclear fuel (CSNF) and codisposed high-level waste glass (HLWG) and N Reactor spent fuel (CDNR). The in-package chemistry model includes two sub-models, the first a water vapor condensation (WVC) model, where water enters a waste package as vapor and forms a film on the waste package components with subsequent film reactions with the waste package materials and waste form--this is a no-flow model, the reacted fluids do not exit the waste package via advection. The second sub-model of the in-package chemistry model is the seepage dripping model (SDM), where water, water that may have seeped into the repository from the surrounding rock, enters a failed waste package and reacts with the waste package components and waste form, and then exits the waste package with no accumulation of reacted water in the waste package. Both of the submodels of the in-package chemistry model are film models in contrast to past in-package chemistry models where all of the waste package pore space was filled with water. The current in

Comprehensive cluster analysis with Transitivity Clustering.

Science.gov (United States)

Wittkop, Tobias; Emig, Dorothea; Truss, Anke; Albrecht, Mario; Böcker, Sebastian; Baumbach, Jan

2011-03-01

Transitivity Clustering is a method for the partitioning of biological data into groups of similar objects, such as genes, for instance. It provides integrated access to various functions addressing each step of a typical cluster analysis. To facilitate this, Transitivity Clustering is accessible online and offers three user-friendly interfaces: a powerful stand-alone version, a web interface, and a collection of Cytoscape plug-ins. In this paper, we describe three major workflows: (i) protein (super)family detection with Cytoscape, (ii) protein homology detection with incomplete gold standards and (iii) clustering of gene expression data. This protocol guides the user through the most important features of Transitivity Clustering and takes ∼1 h to complete.

Performance Analysis of Memory Transfers and GEMM Subroutines on NVIDIA Tesla GPU Cluster

Energy Technology Data Exchange (ETDEWEB)

Allada, Veerendra, Benjegerdes, Troy; Bode, Brett

2009-08-31

Commodity clusters augmented with application accelerators are evolving as competitive high performance computing systems. The Graphical Processing Unit (GPU) with a very high arithmetic density and performance per price ratio is a good platform for the scientific application acceleration. In addition to the interconnect bottlenecks among the cluster compute nodes, the cost of memory copies between the host and the GPU device have to be carefully amortized to improve the overall efficiency of the application. Scientific applications also rely on efficient implementation of the BAsic Linear Algebra Subroutines (BLAS), among which the General Matrix Multiply (GEMM) is considered as the workhorse subroutine. In this paper, they study the performance of the memory copies and GEMM subroutines that are critical to port the computational chemistry algorithms to the GPU clusters. To that end, a benchmark based on the NetPIPE framework is developed to evaluate the latency and bandwidth of the memory copies between the host and the GPU device. The performance of the single and double precision GEMM subroutines from the NVIDIA CUBLAS 2.0 library are studied. The results have been compared with that of the BLAS routines from the Intel Math Kernel Library (MKL) to understand the computational trade-offs. The test bed is a Intel Xeon cluster equipped with NVIDIA Tesla GPUs.

Performance Analysis of Memory Transfers and GEMM Subroutines on NVIDIA Tesla GPU Cluster

International Nuclear Information System (INIS)

Allada, Veerendra; Benjegerdes, Troy; Bode, Brett

2009-01-01

Commodity clusters augmented with application accelerators are evolving as competitive high performance computing systems. The Graphical Processing Unit (GPU) with a very high arithmetic density and performance per price ratio is a good platform for the scientific application acceleration. In addition to the interconnect bottlenecks among the cluster compute nodes, the cost of memory copies between the host and the GPU device have to be carefully amortized to improve the overall efficiency of the application. Scientific applications also rely on efficient implementation of the BAsic Linear Algebra Subroutines (BLAS), among which the General Matrix Multiply (GEMM) is considered as the workhorse subroutine. In this paper, they study the performance of the memory copies and GEMM subroutines that are critical to port the computational chemistry algorithms to the GPU clusters. To that end, a benchmark based on the NetPIPE framework is developed to evaluate the latency and bandwidth of the memory copies between the host and the GPU device. The performance of the single and double precision GEMM subroutines from the NVIDIA CUBLAS 2.0 library are studied. The results have been compared with that of the BLAS routines from the Intel Math Kernel Library (MKL) to understand the computational trade-offs. The test bed is a Intel Xeon cluster equipped with NVIDIA Tesla GPUs.

Cluster-cluster correlations and constraints on the correlation hierarchy

Science.gov (United States)

Hamilton, A. J. S.; Gott, J. R., III

1988-01-01

The hypothesis that galaxies cluster around clusters at least as strongly as they cluster around galaxies imposes constraints on the hierarchy of correlation amplitudes in hierachical clustering models. The distributions which saturate these constraints are the Rayleigh-Levy random walk fractals proposed by Mandelbrot; for these fractal distributions cluster-cluster correlations are all identically equal to galaxy-galaxy correlations. If correlation amplitudes exceed the constraints, as is observed, then cluster-cluster correlations must exceed galaxy-galaxy correlations, as is observed.

CONSTRAINING CLUSTER PHYSICS WITH THE SHAPE OF X-RAY CLUSTERS: COMPARISON OF LOCAL X-RAY CLUSTERS VERSUS ΛCDM CLUSTERS

International Nuclear Information System (INIS)

Lau, Erwin T.; Nagai, Daisuke; Kravtsov, Andrey V.; Vikhlinin, Alexey; Zentner, Andrew R.

2012-01-01

Recent simulations of cluster formation have demonstrated that condensation of baryons into central galaxies during cluster formation can drive the shape of the gas distribution in galaxy clusters significantly rounder out to their virial radius. These simulations generally predict stellar fractions within cluster virial radii that are ∼2-3 times larger than the stellar masses deduced from observations. In this paper, we compare ellipticity profiles of simulated clusters performed with varying input physics (radiative cooling, star formation, and supernova feedback) to the cluster ellipticity profiles derived from Chandra and ROSAT observations, in an effort to constrain the fraction of gas that cools and condenses into the central galaxies within clusters. We find that local relaxed clusters have an average ellipticity of ε = 0.18 ± 0.05 in the radial range of 0.04 ≤ r/r 500 ≤ 1. At larger radii r > 0.1r 500 , the observed ellipticity profiles agree well with the predictions of non-radiative simulations. In contrast, the ellipticity profiles of simulated clusters that include dissipative gas physics deviate significantly from the observed ellipticity profiles at all radii. The dissipative simulations overpredict (underpredict) ellipticity in the inner (outer) regions of galaxy clusters. By comparing simulations with and without dissipative gas physics, we show that gas cooling causes the gas distribution to be more oblate in the central regions, but makes the outer gas distribution more spherical. We find that late-time gas cooling and star formation are responsible for the significantly oblate gas distributions in cluster cores, but the gas shapes outside of cluster cores are set primarily by baryon dissipation at high redshift (z ≥ 2). Our results indicate that the shapes of X-ray emitting gas in galaxy clusters, especially at large radii, can be used to place constraints on cluster gas physics, making it potential probes of the history of baryonic

A Quantum Chemistry Concept Inventory for Physical Chemistry Classes

Science.gov (United States)

Dick-Perez, Marilu; Luxford, Cynthia J.; Windus, Theresa L.; Holme, Thomas

2016-01-01

A 14-item, multiple-choice diagnostic assessment tool, the quantum chemistry concept inventory or QCCI, is presented. Items were developed based on published student misconceptions and content coverage and then piloted and used in advanced physical chemistry undergraduate courses. In addition to the instrument itself, data from both a pretest,…

Annual report 1983 Chemistry Department

International Nuclear Information System (INIS)

Funck, J.; Larsen, E.; Nielsen, O.J.

1984-05-01

This report contains a brief survey of the main activities in the Chemistry Department. All articles and reports published and lectures given in 1983 are presented. The facilities and equipment are barely mentioned. The activities are divided into nine groups: 1. radioisotope chemistry 2. analytical- and organic chemistry 3. environmental chemistry 4. polymer chemistry 5. geochemistry and waste disposal 6. radical chemstry 7. positron annihilation 8. mineral processing 9. general. (author)

Fundamentals of reactor chemistry

International Nuclear Information System (INIS)

Akatsu, Eiko

1981-12-01

In the Nuclear Engineering School of JAERI, many courses are presented for the people working in and around the nuclear reactors. The curricula of the courses contain also the subject material of chemistry. With reference to the foreign curricula, a plan of educational subject material of chemistry in the Nuclear Engineering School of JAERI was considered, and the fundamental part of reactor chemistry was reviewed in this report. Since the students of the Nuclear Engineering School are not chemists, the knowledge necessary in and around the nuclear reactors was emphasized in order to familiarize the students with the reactor chemistry. The teaching experience of the fundamentals of reactor chemistry is also given. (author)

Revealing isomerism in sodium-water clusters: Photoionization spectra of Na(H2O)n (n = 2-90).

Science.gov (United States)

Dierking, Christoph W; Zurheide, Florian; Zeuch, Thomas; Med, Jakub; Parez, Stanislav; Slavíček, Petr

2017-06-28

Soft ionization of sodium tagged polar clusters is increasingly used as a powerful technique for sizing and characterization of small aerosols with possible application, e.g., in atmospheric chemistry or combustion science. Understanding the structure and photoionization of the sodium doped clusters is critical for such applications. In this work, we report on measurements of photoionization spectra for sodium doped water clusters containing 2-90 water molecules. While most of the previous studies focused on the ionization threshold of the Na(H 2 O) n clusters, we provide for the first time full photoionization spectra, including the high-energy region, which are used as reference for a comparison with theory. As reported in previous work, we have seen an initial drop of the appearance ionization energy with cluster size to values of about 3.2 eV for nphotoionization spectrum. Simulations at elevated temperatures show an increased abundance of isomers with low ionization energies, an entropic effect enabling size selective infrared action spectroscopy, based on near threshold photoionization of Na(H 2 O) n clusters. In addition, simulations of the sodium pick-up process were carried out to study the gradual formation of the hydrated electron which is the basis of the sodium-tagging sizing.

Studies of cluster-assembled materials: From gas phase to condensed phase

Science.gov (United States)

Gao, Lin

Clusters, defined as "a number of similar things that occur together" in Webster's dictionary, has different meanings depending on the given subject. To physicists and chemists, the word cluster means "a group of atoms or molecules formed by interactions ranging from very weak van der Waals interactions to strong ionic bonds." Unlike molecules, which are made by nature and are stable under ambient conditions, clusters discovered in a laboratory are often metastable. Molecules have specific stoichiometry, whereas the cluster's composition can usually be altered atom by atom. Thus, clusters can be taken as intrinsically "artificial molecules" with considerably more tunabilities in their properties. Research into the relative stability and instability of clusters has in recent years become a very active research area, especially following the study by Khanna and Castleman that first suggested that by varying size and composition, clusters can expand the periodic table to the 3 rd-dimension; that is, clusters can mimic the chemistry of atoms and may, therefore, be used as the building blocks of new materials. The discovery of Met-Cars has drawn worldwide interests and has been actively investigated by researchers from a variety of fields, including physics, chemistry and material science. However, the unsuccessful search for a solvent capable of isolating Met-Cars has impeded progress in characterizing the material in the condensed state and, hence, limited its potential applications as a novel nanoscale material. An alternative method involving the deposition of mass-gated species and the subsequent structural investigation via Transmission Electron Microscopy (TEM) has been employed. With particularly interesting results, soft-landed deposits of zirconium Met-Cars were found to form a face-centered-cubic (FCC) structure with a lattice parameter ˜ 15A. The production of Met-Cars is conducted with the direct laser vaporization (DLV) of metal/graphite composite pellets

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)

Convex Clustering: An Attractive Alternative to Hierarchical Clustering

Science.gov (United States)

Chen, Gary K.; Chi, Eric C.; Ranola, John Michael O.; Lange, Kenneth

2015-01-01

The primary goal in cluster analysis is to discover natural groupings of objects. The field of cluster analysis is crowded with diverse methods that make special assumptions about data and address different scientific aims. Despite its shortcomings in accuracy, hierarchical clustering is the dominant clustering method in bioinformatics. Biologists find the trees constructed by hierarchical clustering visually appealing and in tune with their evolutionary perspective. Hierarchical clustering operates on multiple scales simultaneously. This is essential, for instance, in transcriptome data, where one may be interested in making qualitative inferences about how lower-order relationships like gene modules lead to higher-order relationships like pathways or biological processes. The recently developed method of convex clustering preserves the visual appeal of hierarchical clustering while ameliorating its propensity to make false inferences in the presence of outliers and noise. The solution paths generated by convex clustering reveal relationships between clusters that are hidden by static methods such as k-means clustering. The current paper derives and tests a novel proximal distance algorithm for minimizing the objective function of convex clustering. The algorithm separates parameters, accommodates missing data, and supports prior information on relationships. Our program CONVEXCLUSTER incorporating the algorithm is implemented on ATI and nVidia graphics processing units (GPUs) for maximal speed. Several biological examples illustrate the strengths of convex clustering and the ability of the proximal distance algorithm to handle high-dimensional problems. CONVEXCLUSTER can be freely downloaded from the UCLA Human Genetics web site at http://www.genetics.ucla.edu/software/ PMID:25965340

[Ti8Zr2O12(COO16] Cluster: An Ideal Inorganic Building Unit for Photoactive Metal–Organic Frameworks

Directory of Open Access Journals (Sweden)

Shuai Yuan

2017-11-01

Full Text Available Metal–organic frameworks (MOFs based on Ti-oxo clusters (Ti-MOFs represent a naturally self-assembled superlattice of TiO2 nanoparticles separated by designable organic linkers as antenna chromophores, epitomizing a promising platform for solar energy conversion. However, despite the vast, diverse, and well-developed Ti-cluster chemistry, only a scarce number of Ti-MOFs have been documented. The synthetic conditions of most Ti-based clusters are incompatible with those required for MOF crystallization, which has severely limited the development of Ti-MOFs. This challenge has been met herein by the discovery of the [Ti8Zr2O12­(COO16] cluster as a nearly ideal building unit for photoactive MOFs. A family of isoreticular photoactive MOFs were assembled, and their orbital alignments were fine-tuned by rational functionalization of organic linkers under computational guidance. These MOFs demonstrate high porosity, excellent chemical stability, tunable photoresponse, and good activity toward photocatalytic hydrogen evolution reactions. The discovery of the [Ti8Zr2O12­(COO16] cluster and the facile construction of photoactive MOFs from this cluster shall pave the way for the development of future Ti-MOF-based photocatalysts.

[Ti8Zr2O12(COO)16] Cluster: An Ideal Inorganic Building Unit for Photoactive Metal-Organic Frameworks.

Science.gov (United States)

Yuan, Shuai; Qin, Jun-Sheng; Xu, Hai-Qun; Su, Jie; Rossi, Daniel; Chen, Yuanping; Zhang, Liangliang; Lollar, Christina; Wang, Qi; Jiang, Hai-Long; Son, Dong Hee; Xu, Hongyi; Huang, Zhehao; Zou, Xiaodong; Zhou, Hong-Cai

2018-01-24

Metal-organic frameworks (MOFs) based on Ti-oxo clusters (Ti-MOFs) represent a naturally self-assembled superlattice of TiO 2 nanoparticles separated by designable organic linkers as antenna chromophores, epitomizing a promising platform for solar energy conversion. However, despite the vast, diverse, and well-developed Ti-cluster chemistry, only a scarce number of Ti-MOFs have been documented. The synthetic conditions of most Ti-based clusters are incompatible with those required for MOF crystallization, which has severely limited the development of Ti-MOFs. This challenge has been met herein by the discovery of the [Ti 8 Zr 2 O 12 (COO) 16 ] cluster as a nearly ideal building unit for photoactive MOFs. A family of isoreticular photoactive MOFs were assembled, and their orbital alignments were fine-tuned by rational functionalization of organic linkers under computational guidance. These MOFs demonstrate high porosity, excellent chemical stability, tunable photoresponse, and good activity toward photocatalytic hydrogen evolution reactions. The discovery of the [Ti 8 Zr 2 O 12 (COO) 16 ] cluster and the facile construction of photoactive MOFs from this cluster shall pave the way for the development of future Ti-MOF-based photocatalysts.

Research on condensed matter and atomic physics, using major experimental facilities and devices: Physics, chemistry, biology. Reports on results. Vol. 1. 1. Atomic and molecular physics. 2. Physics and chemistry of surfaces and interfaces

International Nuclear Information System (INIS)

1993-01-01

This report in three volumes substantiates the contents of the programme survey published in September 1989. The progress reports cover the following research areas: Vol. I, (1). Atomic and molecular physics - free atoms, molecules, macromolecules, clusters, matrix-isolated atoms and molecules. (2) Physics and chemistry of surfaces and interfaces - epitaxy, surface structure, adsorption, electrical, magnetic, and optical properties, thin films, synthetic layer structure. Vol. II, (3). Solid-state physics, and materials science -structural research, lattice dynamics, magnetic structure and dynamics, electronic states; load; spin and pulse density fluctuations; diffusion and internal motion, defects, unordered systems and liquids. Vol. III, (4). Chemistry - bonding and structure, kinetics and reaction mechanisms, polymer research, analysis and synthesis. (5). Biology, - structure and dynamics of biological macromolecules, membrane and cell biology. (6) Development of methods and instruments - neutron sources, synchrotron sources, special accelerators, research with interlinked systems and devices. (orig.) [de

Application of the principle of supramolecular chemistry in the fields of radiochemistry and radiation chemistry

International Nuclear Information System (INIS)

Shen Xinghai; Chen Qingde; Gao Hongcheng

2008-01-01

Supramolecular chemistry, one of the front fields in chemistry, is defined as 'chemistry beyond the molecule', bearing on the organized entities of higher complexity that result from the association of two or more chemical species held together by intermolecular forces. This article focuses on the application of the principle of supramolecular chemistry in the fields of radiochemistry and radiation chemistry. The following aspects are concerned: (1) the recent progress of supramolecular chemistry; (2) the application of the principle of supramolecular chemistry and the functions of supramolecular system, i.e., recognition, assembly and translocation, in the extraction of nuclides; (3) the application of microemulsion, ionic imprinted polymers, ionic liquids and cloud point extraction in the enrichment of nuclides; (4) the radiation effect of supramolecular systems. (authors)

Henry Taube and Coordination Chemistry

Science.gov (United States)

dropdown arrow Site Map A-Z Index Menu Synopsis Henry Taube and Coordination Chemistry Resources with Professor of Chemistry, Emeritus, at Stanford University, received the 1983 Nobel Prize in Chemistry " there from 1940-41. "I became deeply interested in chemistry soon after I came to Berkeley,"

Les clusters moléculaires. Applications en catalyse homogène et hétérogène Molecular Clusters. Applications in Homogeneous and Heterogeneous Catalysis

Directory of Open Access Journals (Sweden)

Dorbon M.

2006-11-01

Full Text Available Le présent article ne prétend pas être une étude bibliographique complète. II ne s'agit que d'une synthèse dont le but est l'introduction à un secteur de la chimie encore jeune et surtout très vaste et plein d'avenir. Les clusters métalliques sont des composés constitués d'atomes métalliques liés entre eux et généralement entourés de ligands ; ils présentent à la fois certaines des caractéristiques des complexes uninucléaires d'une part et des métaux massiques d'autre part. D'un point de vue fondamental, la chimie des clusters représente un domaine encore neuf et particulièrement vaste. D'un point de vue pratique, leur principal intérêt réside dans le fait que bon nombre d'entre eux ont fait preuve de propriétés catalytiques remarquables tant en mode homogène qu'en mode hétérogène. Ils doivent être pris en considération par les industriels de la chimie car certains peuvent être impliqués dans des réactions aussi importantes que la synthèse de Fischer-Tropsch, l'hydrogénation des oléfines, la réaction de gaz à l'eau et la fixation biologique de l'azote atmosphérique. This article does not pretend to be an exhaustive bibliographic survey. It is merely a synthesis intended as an introduction to a sector of chemistry which is still young and especially is very vast and promising. Metal clusters are compounds made up of metal atours bonded together and generally surrounded by ligands. They have various characteristics of both mono-nuclear complexes and bulk metals. From a fundamental point of view, the chemistry of clusters is still a new and particularly vast field. From a practical point of view, the importance of clusters lies in the fact that a good number of them have shown proof of remarkable catalytic properties, both homogeneous and heterogeneous. They must henceforth be taken into consideration by chemical engineers because some of them may be involved in such important reactions as the Fischer

AECL research programs in chemistry

International Nuclear Information System (INIS)

Crocker, I.H.; Eastwood, T.A.; Smith, D.R.; Stewart, R.B.; Tomlinson, M.; Torgerson, D.F.

1980-09-01

Fundamental or underlying research in chemistry is being done in AECL laboratories to further the understanding of processes involved in current nuclear energy systems and maintain an awareness of progress at the frontiers of chemical research so that new advances can be turned to advantage in future AECL endeavours. The report introduces the current research topics and describes them briefly under the following headings: radiation chemistry, isotope separation, high temperature solution chemistry, fuel reprocessing chemistry, and analytical chemistry. (auth)

Analysis of Students’ Missed Organic Chemistry Quiz Questions that Stress the Importance of Prior General Chemistry Knowledge

OpenAIRE

Julie Ealy

2018-01-01

A concern about students’ conceptual difficulties in organic chemistry prompted this study. It was found that prior knowledge from general chemistry was critical in organic chemistry, but what were some of the concepts that comprised that prior knowledge? Therefore an analysis of four years of organic chemistry quiz data was undertaken. Multiple general chemistry concepts were revealed that are essential prior knowledge in organic chemistry. The general chemistry concepts that were foun...

Cluster management.

Science.gov (United States)

Katz, R

1992-11-01

Cluster management is a management model that fosters decentralization of management, develops leadership potential of staff, and creates ownership of unit-based goals. Unlike shared governance models, there is no formal structure created by committees and it is less threatening for managers. There are two parts to the cluster management model. One is the formation of cluster groups, consisting of all staff and facilitated by a cluster leader. The cluster groups function for communication and problem-solving. The second part of the cluster management model is the creation of task forces. These task forces are designed to work on short-term goals, usually in response to solving one of the unit's goals. Sometimes the task forces are used for quality improvement or system problems. Clusters are groups of not more than five or six staff members, facilitated by a cluster leader. A cluster is made up of individuals who work the same shift. For example, people with job titles who work days would be in a cluster. There would be registered nurses, licensed practical nurses, nursing assistants, and unit clerks in the cluster. The cluster leader is chosen by the manager based on certain criteria and is trained for this specialized role. The concept of cluster management, criteria for choosing leaders, training for leaders, using cluster groups to solve quality improvement issues, and the learning process necessary for manager support are described.

Electrostatics in Chemistry

Indian Academy of Sciences (India)

fundamental concepts of electrostatics as applied to atoms and molecules. The electric ... chemistry, the chemistry of the covalent bond, deals with the structures ..... the position of an asteroid named Ceres ... World Scientific. Singapore, 1992.

Scavenging and recombination kinetics in radiation chemistry.

Science.gov (United States)

Al-Samra, Eyad H; Green, Nicholas J B

2017-08-02

This work describes stochastic models developed to study the competition between radical scavenging and recombination for simple model systems typical of radiation chemistry, where the reactive particles are tightly clustered and reactions are assumed fully diffusion limited. Three models are developed: a Monte Carlo random flights model with a periodic boundary condition for scavengers, Monte Carlo simulations in which the scavenging rate is calculated from the Smoluchowski theory for diffusion-limited reactions and a modification of the independent reaction times method where the scavengers close to the spur are explicitly included and the scavengers further away are treated as a continuum. The results indicate that the Smoluchowski theory makes a systematic overestimate of the scavenging rate when such competition is present. A correction for the Smoluchowski rate constant is suggested, an analytical justification is presented and it is tested against the simulations, and shown to be a substantial improvement.

Actinide chemistry using singlet-paired coupled cluster and its combinations with density functionals

Science.gov (United States)

Garza, Alejandro J.; Sousa Alencar, Ana G.; Scuseria, Gustavo E.

2015-12-01

Singlet-paired coupled cluster doubles (CCD0) is a simplification of CCD that relinquishes a fraction of dynamic correlation in order to be able to describe static correlation. Combinations of CCD0 with density functionals that recover specifically the dynamic correlation missing in the former have also been developed recently. Here, we assess the accuracy of CCD0 and CCD0+DFT (and variants of these using Brueckner orbitals) as compared to well-established quantum chemical methods for describing ground-state properties of singlet actinide molecules. The f0 actinyl series (UO22+, NpO23+, PuO24+), the isoelectronic NUN, and thorium (ThO, ThO2+) and nobelium (NoO, NoO2) oxides are studied.

Assessment of interaction-strength interpolation formulas for gold and silver clusters

Science.gov (United States)

Giarrusso, Sara; Gori-Giorgi, Paola; Della Sala, Fabio; Fabiano, Eduardo

2018-04-01

The performance of functionals based on the idea of interpolating between the weak- and the strong-interaction limits the global adiabatic-connection integrand is carefully studied for the challenging case of noble-metal clusters. Different interpolation formulas are considered and various features of this approach are analyzed. It is found that these functionals, when used as a correlation correction to Hartree-Fock, are quite robust for the description of atomization energies, while performing less well for ionization potentials. Future directions that can be envisaged from this study and a previous one on main group chemistry are discussed.

Spectral simulations of polar diatomic molecules immersed in He clusters: application to the ICl (X) molecule

International Nuclear Information System (INIS)

Villarreal, P; Lara-Castells, M P de; Prosmiti, R; Delgado-Barrio, G; Lopez-Duran, D; Gianturco, F A; Jellinek, J

2007-01-01

A recently developed quantum-chemistry-like methodology to study molecules solvated in atomic clusters is applied to the ICl (iodine chloride) polar diatomic molecule immersed in clusters of He atoms. The atoms of the solvent clusters are treated as the 'electrons' and the solvated molecule as a structured 'nucleus' of the combined solvent-solute system. The helium-helium and helium-dopant interactions are represented by parametrized two-body and ab initio three-body potentials, respectively. The ground-state wavefunctions are used to compute the infrared (IR) spectra of the solvated molecule. In agreement with the experimental observations, the computed spectra exhibit considerable differences depending on whether the solvent cluster is comprised of bosonic ( 4 He) or fermionic ( 3 He) atoms. The source of these differences is attributed to the different spin-statistics of the solvent clusters. The bosonic versus fermionic nature of the solvent is reflected in the IR absorption selection rules. Only P and R branches with single state transitions appear in the spectrum when the molecule is solvated in a bosonic cluster. On the other hand, when the solvent represents a fermionic environment, quasi-degenerate multiplets of spin states contribute to each branch and, in addition, the Q-branch becomes also allowed. Combined, these two factors explain the more congested nature of the spectrum in the fermionic case

Relational Analysis of College Chemistry-Major Students' Conceptions of and Approaches to Learning Chemistry

Science.gov (United States)

Li, Wei-Ting; Liang, Jyh-Chong; Tsai, Chin-Chung

2013-01-01

The purpose of this research was to examine the relationships between conceptions of learning and approaches to learning in chemistry. Two questionnaires, conceptions of learning chemistry (COLC) and approaches to learning chemistry (ALC), were developed to identify 369 college chemistry-major students' (220 males and 149 females) conceptions of…

Advances in quantum chemistry

CERN Document Server

Sabin, John R

2013-01-01

Advances in Quantum Chemistry presents surveys of current topics in this rapidly developing field that has emerged at the cross section of the historically established areas of mathematics, physics, chemistry, and biology. It features detailed reviews written by leading international researchers. This volume focuses on the theory of heavy ion physics in medicine.Advances in Quantum Chemistry presents surveys of current topics in this rapidly developing field that has emerged at the cross section of the historically established areas of mathematics, physics, chemistry, and biology. It features

Radiochemistry in chemistry and chemistry related undergraduate programmes in Argentina

International Nuclear Information System (INIS)

Fornaciari Iljadica, M.C.; Furnari, J.C.; Cohen, I.M.

2006-01-01

The evolution of education in Argentina at the university level is described. The detailed search of the educational offer shows that less than half of the universities (35 out of 92) include chemistry and chemistry related undergraduate programmes in their curriculum. The revision of the position of radiochemistry in these programmes reveals that only seven courses on radiochemistry are currently offered. Radiochemistry is included only in few programmes in chemistry and biochemistry. With respect to the programmes in chemical engineering the situation is worse. This offer is strongly concentrated in Buenos Aires and its surroundings. (author)

Addressing the complexity of water chemistry in environmental fate modeling for engineered nanoparticles.

Science.gov (United States)

Sani-Kast, Nicole; Scheringer, Martin; Slomberg, Danielle; Labille, Jérôme; Praetorius, Antonia; Ollivier, Patrick; Hungerbühler, Konrad

2015-12-01

Engineered nanoparticle (ENP) fate models developed to date - aimed at predicting ENP concentration in the aqueous environment - have limited applicability because they employ constant environmental conditions along the modeled system or a highly specific environmental representation; both approaches do not show the effects of spatial and/or temporal variability. To address this conceptual gap, we developed a novel modeling strategy that: 1) incorporates spatial variability in environmental conditions in an existing ENP fate model; and 2) analyzes the effect of a wide range of randomly sampled environmental conditions (representing variations in water chemistry). This approach was employed to investigate the transport of nano-TiO2 in the Lower Rhône River (France) under numerous sets of environmental conditions. The predicted spatial concentration profiles of nano-TiO2 were then grouped according to their similarity by using cluster analysis. The analysis resulted in a small number of clusters representing groups of spatial concentration profiles. All clusters show nano-TiO2 accumulation in the sediment layer, supporting results from previous studies. Analysis of the characteristic features of each cluster demonstrated a strong association between the water conditions in regions close to the ENP emission source and the cluster membership of the corresponding spatial concentration profiles. In particular, water compositions favoring heteroaggregation between the ENPs and suspended particulate matter resulted in clusters of low variability. These conditions are, therefore, reliable predictors of the eventual fate of the modeled ENPs. The conclusions from this study are also valid for ENP fate in other large river systems. Our results, therefore, shift the focus of future modeling and experimental research of ENP environmental fate to the water characteristic in regions near the expected ENP emission sources. Under conditions favoring heteroaggregation in these

Lifting to cluster-tilting objects in higher cluster categories

OpenAIRE

Liu, Pin

2008-01-01

In this note, we consider the $d$-cluster-tilted algebras, the endomorphism algebras of $d$-cluster-tilting objects in $d$-cluster categories. We show that a tilting module over such an algebra lifts to a $d$-cluster-tilting object in this $d$-cluster category.

Data Clustering

Science.gov (United States)

Wagstaff, Kiri L.

2012-03-01

On obtaining a new data set, the researcher is immediately faced with the challenge of obtaining a high-level understanding from the observations. What does a typical item look like? What are the dominant trends? How many distinct groups are included in the data set, and how is each one characterized? Which observable values are common, and which rarely occur? Which items stand out as anomalies or outliers from the rest of the data? This challenge is exacerbated by the steady growth in data set size [11] as new instruments push into new frontiers of parameter space, via improvements in temporal, spatial, and spectral resolution, or by the desire to "fuse" observations from different modalities and instruments into a larger-picture understanding of the same underlying phenomenon. Data clustering algorithms provide a variety of solutions for this task. They can generate summaries, locate outliers, compress data, identify dense or sparse regions of feature space, and build data models. It is useful to note up front that "clusters" in this context refer to groups of items within some descriptive feature space, not (necessarily) to "galaxy clusters" which are dense regions in physical space. The goal of this chapter is to survey a variety of data clustering methods, with an eye toward their applicability to astronomical data analysis. In addition to improving the individual researcher’s understanding of a given data set, clustering has led directly to scientific advances, such as the discovery of new subclasses of stars [14] and gamma-ray bursts (GRBs) [38]. All clustering algorithms seek to identify groups within a data set that reflect some observed, quantifiable structure. Clustering is traditionally an unsupervised approach to data analysis, in the sense that it operates without any direct guidance about which items should be assigned to which clusters. There has been a recent trend in the clustering literature toward supporting semisupervised or constrained

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

Dense Fe cluster-assembled films by energetic cluster deposition

International Nuclear Information System (INIS)

Peng, D.L.; Yamada, H.; Hihara, T.; Uchida, T.; Sumiyama, K.

2004-01-01

High-density Fe cluster-assembled films were produced at room temperature by an energetic cluster deposition. Though cluster-assemblies are usually sooty and porous, the present Fe cluster-assembled films are lustrous and dense, revealing a soft magnetic behavior. Size-monodispersed Fe clusters with the mean cluster size d=9 nm were synthesized using a plasma-gas-condensation technique. Ionized clusters are accelerated electrically and deposited onto the substrate together with neutral clusters from the same cluster source. Packing fraction and saturation magnetic flux density increase rapidly and magnetic coercivity decreases remarkably with increasing acceleration voltage. The Fe cluster-assembled film obtained at the acceleration voltage of -20 kV has a packing fraction of 0.86±0.03, saturation magnetic flux density of 1.78±0.05 Wb/m 2 , and coercivity value smaller than 80 A/m. The resistivity at room temperature is ten times larger than that of bulk Fe metal

Hot stars in young massive clusters: Mapping the current Galactic metallicity

Science.gov (United States)

de la Fuente, Diego; Najarro, Francisco; Davies, Ben; Trombley, Christine; Figer, Donald F.; Herrero, Artemio

2013-06-01

Young Massive Clusters (YMCs) with ages guarantee that these objects present the same chemical composition than the surrounding environment where they are recently born. Finally, the YMCs host very massive stars whose extreme luminosities allow to accomplish detailed spectroscopic analyses even in the most distant regions of the Milky Way. Our group has carried out ISAAC/VLT spectroscopic observations of hot massive stars belonging to several YMCs in different locations around the Galactic disk. As a result, high signal-to-noise, near-infrared spectra of dozens of blue massive stars (including many OB supergiants, Wolf-Rayet stars and a B hypergiant) have been obtained. These data are fully reduced, and NLTE spherical atmosphere modeling is in process. Several line diagnostics will be combined in order to calculate metal abundances accurately for each cluster. The diverse locations of the clusters will allow us to draw a two-dimensional chemical map of the Galactic disk for the first time. The study of the radial and azimuthal variations of elemental abundances will be crucial for understanding the chemical evolution of the Milky Way. Particularly, the ratio between Fe-peak and alpha elements will constitute a powerful tool to investigate the past stellar populations that originated the current Galactic chemistry.

Cluster Physics with Merging Galaxy Clusters

Directory of Open Access Journals (Sweden)

Sandor M. Molnar

2016-02-01

Full Text Available Collisions between galaxy clusters provide a unique opportunity to study matter in a parameter space which cannot be explored in our laboratories on Earth. In the standard LCDM model, where the total density is dominated by the cosmological constant ($Lambda$ and the matter density by cold dark matter (CDM, structure formation is hierarchical, and clusters grow mostly by merging.Mergers of two massive clusters are the most energetic events in the universe after the Big Bang,hence they provide a unique laboratory to study cluster physics.The two main mass components in clusters behave differently during collisions:the dark matter is nearly collisionless, responding only to gravity, while the gas is subject to pressure forces and dissipation, and shocks and turbulenceare developed during collisions. In the present contribution we review the different methods used to derive the physical properties of merging clusters. Different physical processes leave their signatures on different wavelengths, thusour review is based on a multifrequency analysis. In principle, the best way to analyze multifrequency observations of merging clustersis to model them using N-body/HYDRO numerical simulations. We discuss the results of such detailed analyses.New high spatial and spectral resolution ground and space based telescopeswill come online in the near future. Motivated by these new opportunities,we briefly discuss methods which will be feasible in the near future in studying merging clusters.

Spotlight on medicinal chemistry education.

Science.gov (United States)

Pitman, Simone; Xu, Yao-Zhong; Taylor, Peter; Turner, Nicholas; Coaker, Hannah; Crews, Kasumi

2014-05-01

The field of medicinal chemistry is constantly evolving and it is important for medicinal chemists to develop the skills and knowledge required to succeed and contribute to the advancement of the field. Future Medicinal Chemistry spoke with Simone Pitman (SP), Yao-Zhong Xu (YX), Peter Taylor (PT) and Nick Turner (NT) from The Open University (OU), which offers an MSc in Medicinal Chemistry. In the interview, they discuss the MSc course content, online teaching, the future of medicinal chemistry education and The OU's work towards promoting widening participation. SP is a Qualifications Manager in the Science Faculty at The OU. She joined The OU in 1993 and since 1998 has been involved in the Postgraduate Medicinal Chemistry provision at The OU. YX is a Senior Lecturer in Bioorganic Chemistry at The OU. He has been with The OU from 2001, teaching undergraduate courses of all years and chairing the master's course on medicinal chemistry. PT is a Professor of Organic Chemistry at The OU and has been involved with the production and presentation of The OU courses in Science and across the university for over 30 years, including medicinal chemistry modules at postgraduate level. NT is a Lecturer in Analytical Science at The OU since 2009 and has been involved in the production of analytical sciences courses, as well as contributing to the presentation of a number of science courses including medicinal chemistry.

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

Theoretical chemistry in Belgium a topical collection from theoretical chemistry accounts

CERN Document Server

Champagne, Benoît; De Proft, Frank; Leyssens, Tom

2014-01-01

Readers of this volume can take a tour around the research locations in Belgium which are active in theoretical and computational chemistry. Selected researchers from Belgium present research highlights of their work. Originally published in the journal Theoretical Chemistry Accounts, these outstanding contributions are now available in a hardcover print format. This volume will be of benefit in particular to those research groups and libraries that have chosen to have only electronic access to the journal. It also provides valuable content for all researchers in theoretical chemistry.

Benchmark CCSD(T) and DFT study of binding energies in Be7 - 12: in search of reliable DFT functional for beryllium clusters

Science.gov (United States)

Labanc, Daniel; Šulka, Martin; Pitoňák, Michal; Černušák, Ivan; Urban, Miroslav; Neogrády, Pavel

2018-05-01

We present a computational study of the stability of small homonuclear beryllium clusters Be7 - 12 in singlet electronic states. Our predictions are based on highly correlated CCSD(T) coupled cluster calculations. Basis set convergence towards the complete basis set limit as well as the role of the 1s core electron correlation are carefully examined. Our CCSD(T) data for binding energies of Be7 - 12 clusters serve as a benchmark for performance assessment of several density functional theory (DFT) methods frequently used in beryllium cluster chemistry. We observe that, from Be10 clusters on, the deviation from CCSD(T) benchmarks is stable with respect to size, and fluctuating within 0.02 eV error bar for most examined functionals. This opens up the possibility of scaling the DFT binding energies for large Be clusters using CCSD(T) benchmark values for smaller clusters. We also tried to find analogies between the performance of DFT functionals for Be clusters and for the valence-isoelectronic Mg clusters investigated recently in Truhlar's group. We conclude that it is difficult to find DFT functionals that perform reasonably well for both beryllium and magnesium clusters. Out of 12 functionals examined, only the M06-2X functional gives reasonably accurate and balanced binding energies for both Be and Mg clusters.

Are clusters of dietary patterns and cluster membership stable over time? Results of a longitudinal cluster analysis study.

Science.gov (United States)

Walthouwer, Michel Jean Louis; Oenema, Anke; Soetens, Katja; Lechner, Lilian; de Vries, Hein

2014-11-01

Developing nutrition education interventions based on clusters of dietary patterns can only be done adequately when it is clear if distinctive clusters of dietary patterns can be derived and reproduced over time, if cluster membership is stable, and if it is predictable which type of people belong to a certain cluster. Hence, this study aimed to: (1) identify clusters of dietary patterns among Dutch adults, (2) test the reproducibility of these clusters and stability of cluster membership over time, and (3) identify sociodemographic predictors of cluster membership and cluster transition. This study had a longitudinal design with online measurements at baseline (N=483) and 6 months follow-up (N=379). Dietary intake was assessed with a validated food frequency questionnaire. A hierarchical cluster analysis was performed, followed by a K-means cluster analysis. Multinomial logistic regression analyses were conducted to identify the sociodemographic predictors of cluster membership and cluster transition. At baseline and follow-up, a comparable three-cluster solution was derived, distinguishing a healthy, moderately healthy, and unhealthy dietary pattern. Male and lower educated participants were significantly more likely to have a less healthy dietary pattern. Further, 251 (66.2%) participants remained in the same cluster, 45 (11.9%) participants changed to an unhealthier cluster, and 83 (21.9%) participants shifted to a healthier cluster. Men and people living alone were significantly more likely to shift toward a less healthy dietary pattern. Distinctive clusters of dietary patterns can be derived. Yet, cluster membership is unstable and only few sociodemographic factors were associated with cluster membership and cluster transition. These findings imply that clusters based on dietary intake may not be suitable as a basis for nutrition education interventions. Copyright © 2014 Elsevier Ltd. All rights reserved.

Fundamental molecular physics and chemistry. Radiological and Environmental Research Division annual report, October 1981-December 1982. Pt. 1

International Nuclear Information System (INIS)

1983-12-01

This document is the twelfth Annual Report of our Fundamental Molecular Physics and Chemistry Program. Scientifically, the work of the program deals with aspects of the physics and chemistry of molecules related to their interactions with photons, electrons, and other external agents. We chose these areas of study in view of our matic goals; that is to say, we chose them so that the eventual outcome of our work meets some of the needs of the US Department of Energy (DOE) and of other government agencies that support our research. First, we endeavor to determine theoretically and experimentally cross sections for electron and photon interactions with molecules, because those cross sections are indispensable for detailed microscopic analyses of the earliest processes of radiation action on any molecular substance, including biological materials. Those analyses in turn provide a sound basis for radiology and radiation dosimetry. Second, we study the spectroscopy of certain molecules and of small clusters of molecules because this topic is fundamental to the full understanding of atmospheric-pollutant chemistry

Fundamental molecular physics and chemistry. Radiological and Environmental Research Division annual report, October 1981-December 1982. Pt. 1

Energy Technology Data Exchange (ETDEWEB)

1983-12-01

This document is the twelfth Annual Report of our Fundamental Molecular Physics and Chemistry Program. Scientifically, the work of the program deals with aspects of the physics and chemistry of molecules related to their interactions with photons, electrons, and other external agents. We chose these areas of study in view of our matic goals; that is to say, we chose them so that the eventual outcome of our work meets some of the needs of the US Department of Energy (DOE) and of other government agencies that support our research. First, we endeavor to determine theoretically and experimentally cross sections for electron and photon interactions with molecules, because those cross sections are indispensable for detailed microscopic analyses of the earliest processes of radiation action on any molecular substance, including biological materials. Those analyses in turn provide a sound basis for radiology and radiation dosimetry. Second, we study the spectroscopy of certain molecules and of small clusters of molecules because this topic is fundamental to the full understanding of atmospheric-pollutant chemistry.

Future in actinoids coordination chemistry

International Nuclear Information System (INIS)

Kitazawa, Takafumi

2006-01-01

Actinoids coordination chemistry is concerned with spent nuclear fuel reprocessing, specifically with solid-state chemistry of nuclear fuels, separation process with radioactive substances, and geological disposal of high-level radioactive substances. In the 21st century, accumulation of minor actinides, Np, Am, Cm, and others will be realized according with the present program of nuclear energy development. The present article briefly introduces general properties of actinide elements, followed by their coordination chemistry compared with rare earths coordination chemistry. Special facility needed to treat actinoids as well as their chemistry is briefly explained, together with the specific experimental apparatus such as X-ray Absorption Fine Structure (XAFS) and time-resolved laser-induced fluorescence spectrometry (TRLFS) with synchrotron radiation facilities. The effect of coordination with actinoids in the environment chemistry is important in underground disposal of high-level radioactive wastes. For theoretical analysis of the results with actinoids chemistry, relativistic calculation is needed. (S. Ohno)

Chemistry in Context: Analysis of Thematic Chemistry Videos Available Online

Science.gov (United States)

Christensson, Camilla; Sjöström, Jesper

2014-01-01

United Nations declared 2011 to be the International Year of Chemistry. The Swedish Chemical Society chose twelve themes, one for each month, to highlight the connection of chemistry with everyday life. Examples of themes were fashion, climate change, love, sports, communication, health issues, and food. From the themes various context-based…

Clusters and how to make it work : Cluster Strategy Toolkit

NARCIS (Netherlands)

Manickam, Anu; van Berkel, Karel

2014-01-01

Clusters are the magic answer to regional economic development. Firms in clusters are more innovative; cluster policy dominates EU policy; ‘top-sectors’ and excellence are the choice of national policy makers; clusters are ‘in’. But, clusters are complex, clusters are ‘messy’; there is no clear

Cluster dynamics at different cluster size and incident laser wavelengths

International Nuclear Information System (INIS)

Desai, Tara; Bernardinello, Andrea

2002-01-01

X-ray emission spectra from aluminum clusters of diameter -0.4 μm and gold clusters of dia. ∼1.25 μm are experimentally studied by irradiating the cluster foil targets with 1.06 μm laser, 10 ns (FWHM) at an intensity ∼10 12 W/cm 2 . Aluminum clusters show a different spectra compared to bulk material whereas gold cluster evolve towards bulk gold. Experimental data are analyzed on the basis of cluster dimension, laser wavelength and pulse duration. PIC simulations are performed to study the behavior of clusters at higher intensity I≥10 17 W/cm 2 for different size of the clusters irradiated at different laser wavelengths. Results indicate the dependence of cluster dynamics on cluster size and incident laser wavelength

Conference 'Chemistry of hydrides' Proceedings

International Nuclear Information System (INIS)

1991-07-01

This collection of thesis of conference of Chemistry hydrides presents the results of investigations concerning of base questions of chemistry of nonorganic hydrides, including synthesis questions, studying of physical and chemical properties, thermodynamics, analytical chemistry, investigation of structure, equilibriums in the systems of metal-hydrogen, behaviour of nonorganic hydrides in non-water mediums and applying investigations in the chemistry area and technology of nonorganic hydrides

Chemistry of americium

Energy Technology Data Exchange (ETDEWEB)

Schulz, W.W.

1976-01-01

Essential features of the descriptive chemistry of americium are reviewed. Chapter titles are: discovery, atomic and nuclear properties, collateral reading, production and uses, chemistry in aqueous solution, metal, alloys, and compounds, and, recovery, separation, purification. Author and subject indexes are included. (JCB)

Text Clustering Algorithm Based on Random Cluster Core

Directory of Open Access Journals (Sweden)

Huang Long-Jun

2016-01-01

Full Text Available Nowadays clustering has become a popular text mining algorithm, but the huge data can put forward higher requirements for the accuracy and performance of text mining. In view of the performance bottleneck of traditional text clustering algorithm, this paper proposes a text clustering algorithm with random features. This is a kind of clustering algorithm based on text density, at the same time using the neighboring heuristic rules, the concept of random cluster is introduced, which effectively reduces the complexity of the distance calculation.

National Chemistry Teacher Safety Survey

Science.gov (United States)

Plohocki, Barbra A.

This study evaluated the status of secondary school instructional chemistry laboratory safety using a survey instrument which focused on Teacher background Information, Laboratory Safety Equipment, Facility Safety, General Safety, and a Safety Content Knowledge Survey. A fifty question survey instrument based on recent research and questions developed by the researcher was mailed to 500 secondary school chemistry teachers who participated in the 1993 one-week Woodrow Wilson National Fellowship Foundation Chemistry Institute conducted at Princeton University, New Jersey. The data received from 303 respondents was analyzed by t tests and Analysis of Variance (ANOVA). The level of significance for the study was set at ~\\ performance on the Safety Content Knowledge Survey and secondary school chemistry teachers who have had undergraduate and/or graduate safety training and those who have not had undergraduate and/or graduate safety training. Secondary school chemistry teachers who attended school district sponsored safety inservices did not score higher on the Safety Content Knowledge Survey than teachers who did not attend school district sponsored safety inservice sessions. The type of school district (urban, suburban, or rural) had no significant correlation to the type of laboratory safety equipment found in the instructional chemistry laboratory. The certification area (chemistry or other type of certificate which may or may not include chemistry) of the secondary school teacher had no significant correlation to the type of laboratory equipment found in the instructional chemistry laboratory. Overall, this study indicated a majority of secondary school chemistry teachers were interested in attending safety workshops applicable to chemistry safety. Throughout this research project, many teachers indicated they were not adequately instructed on the collegiate level in science safety and had to rely on common sense and self-study in their future teaching careers.

Computação em química teórica: informações técnicas Computation in theoretical chemistry: technical informations

Directory of Open Access Journals (Sweden)

Nelson Henrique Morgon

2001-10-01

Full Text Available The purpose of this work is to demonstrate the usefulness of low cost high performance computers. It is presented technics and software packages used by computational chemists. Access to high-performance computing power remains crucial for many computational quantum chemistry. So, this work introduces the concept of PC cluster, an economical computing plataform.

Green Chemistry

Energy Technology Data Exchange (ETDEWEB)

Collison, Melanie

2011-05-15

Green chemistry is the science of chemistry used in a way that will not use or create hazardous substances. Dr. Rui Resendes is working in this field at GreenCentre Canada, an offshoot of PARTEQ Innovations in Kingston, Ontario. GreenCentre's preliminary findings suggest their licensed product {sup S}witchable Solutions{sup ,} featuring 3 classes of solvents and a surfactant, may be useful in bitumen oil sands extraction.

Survey of PWR water chemistry

International Nuclear Information System (INIS)

Gorman, J.

1989-02-01

This report surveys available information regarding primary and secondary water chemistries of pressurized water reactors (PWRs) and the impact of these water chemistries on reactor operation. The emphasis of the document is on aspects of water chemistry that affect the integrity of the primary pressure boundary and the radiation dose associated with maintenance and operation. The report provides an historical overview of the development of primary and secondary water chemistries, and describes practices currently being followed. Current problems and areas of research associated with water chemistry are described. Recommendations for further research are included. 183 refs., 9 figs., 19 tabs

Promoting Chemistry Learning through Undergraduate Work Experience in the Chemistry Lab: A Practical Approach

Science.gov (United States)

Yu, Hong-Bin

2015-01-01

Hiring undergraduate lab assistants in chemistry departments is common in college. However, few studies have focused on promoting undergraduate chemistry learning and thinking skills through this work experience in chemistry teaching laboratories. This article discusses the strategy we implemented in the lab assistant program. The…

Future perspectives of radiation chemistry

International Nuclear Information System (INIS)

Hatano, Yoshihiko

2009-01-01

Future perspectives of radiation chemistry are discussed by the analysis of the related information in detail as obtained from our recent surveys of publications and scientific meetings in radiation chemistry and its neighboring research fields, giving some examples, and are summarized as follows. (1) Traditionally important core-parts of radiation chemistry should be activated more. The corresponding research programs are listed in detail. (2) Research fields of physics, chemistry, biology, medicine, and technology in radiation research should interact more among them with each other. (3) Basic research of radiation chemistry should interact more with its applied research. (4) Interface research fields with radiation chemistry should be produced more with mutually common viewpoints and research interests between the two. Interfaces are not only applied research but also basic one.

Areva's water chemistry guidebook with chemistry guidelines for next generation plants (AREVA EPRTM reactors)

International Nuclear Information System (INIS)

Ryckelynck, N.; Chahma, F.; Caris, N.; Guillermier, P.; Brun, C.; Caron-Charles, M.; Lamanna, L.; Fandrich, J.; Jaeggy, M.; Stellwag, B.

2012-09-01

Over the years, AREVA globally has maintained a strong expertise in LWR water chemistry and has been focused on minimizing short-term and long-term detrimental effects of chemistry for startup, operation and shutdown chemistry for all key plant components (material integrity and reliability, promote optimal thermal performances, etc.) and fuel. Also AREVA is focused on minimizing contamination and equipment/plant dose rates. Current Industry Guidelines (EPRI, VGB, etc.) provide utilities with selected chemistry guidance for the current operating fleet. With the next generation of PWR plants (e.g. AREVA's EPR TM reactor), materials of construction and design have been optimized based on industry lessons learned over the last 50+ years. To support the next generation design, AREVA water chemistry experts, have subsequently developed a Chemistry Guidebook with chemistry guidelines based on an analysis of the current international practices, plant operating experience, R and D data and calculation codes now available and/or developed by AREVA. The AREVA LWR chemistry Guidebook can be used to help resolve utility and safety authority questions and addresses regulation requirement questions/issues for next generation plants. The Chemistry Guidebook provides water chemistry guidelines for primary coolant, secondary side circuit and auxiliary systems during startup, normal operation and shutdown conditions. It also includes conditioning and impurity limits, along with monitoring locations and frequency requirements. The Chemistry Guidebook Guidelines will be used as a design reference for AREVA's next generation plants (e.g. EPR TM reactor). (authors)

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

The quadruple bottom line: the advantages of incorporating Green Chemistry into the undergraduate chemistry major

Science.gov (United States)

Bodner, George M.

2017-08-01

When the author first became involved with the Green Chemistry movement, he noted that his colleagues in industry who were involved in one of the ACS Green Chemistry Institute® industrial roundtables emphasized the take-home message they described as the "triple bottom line." They noted that introducing Green Chemistry in industrial settings had economic, social, and environmental benefits. As someone who first went to school at age 5, and has been "going to school" most days for 65 years, it was easy for the author to see why introducing Green Chemistry into academics had similar beneficial effects within the context of economic, social and environmental domains at the college/university level. He was prepared to understand why faculty who had taught traditional courses often saw the advantage of incorporating Green Chemistry into the courses they teach. What was not as obvious is why students who were encountering chemistry for the first time were often equally passionate about the Green Chemistry movement. Recent attention has been paid, however, to a model that brings clarity to the hitherto vague term of "relevance" that might explain why integrating Green Chemistry into the undergraduate chemistry classroom can achieve a "quadruple bottom-line" for students because of potentially positive effects of adding a domain of "relevance" to the existing economic, social, and environmental domains.

System approach to chemistry course

OpenAIRE

Lorina E. Kruglova; Valentina G. Derendyaeva

2010-01-01

The article considers the raise of chemistry profile for engineers and constructors training, discloses the system approach to chemistry course and singles out the most important modules from the course of general chemistry for construction industry.

GibbsCluster: unsupervised clustering and alignment of peptide sequences

DEFF Research Database (Denmark)

Andreatta, Massimo; Alvarez, Bruno; Nielsen, Morten

2017-01-01

motif characterizing each cluster. Several parameters are available to customize cluster analysis, including adjustable penalties for small clusters and overlapping groups and a trash cluster to remove outliers. As an example application, we used the server to deconvolute multiple specificities in large......-scale peptidome data generated by mass spectrometry. The server is available at http://www.cbs.dtu.dk/services/GibbsCluster-2.0....

Analysis of NFU-1 metallocofactor binding-site substitutions-impacts on iron-sulfur cluster coordination and protein structure and function.

Science.gov (United States)

Wesley, Nathaniel A; Wachnowsky, Christine; Fidai, Insiya; Cowan, J A

2017-11-01

Iron-sulfur (Fe/S) clusters are ancient prosthetic groups found in numerous metalloproteins and are conserved across all kingdoms of life due to their diverse, yet essential functional roles. Genetic mutations to a specific subset of mitochondrial Fe/S cluster delivery proteins are broadly categorized as disease-related under multiple mitochondrial dysfunction syndrome (MMDS), with symptoms indicative of a general failure of the metabolic system. Multiple mitochondrial dysfunction syndrome 1 (MMDS1) arises as a result of the missense mutation in NFU1, an Fe/S cluster scaffold protein, which substitutes a glycine near the Fe/S cluster-binding pocket to a cysteine (p.Gly208Cys). This substitution has been shown to promote protein dimerization such that cluster delivery to NFU1 is blocked, preventing downstream cluster trafficking. However, the possibility of this additional cysteine, located adjacent to the cluster-binding site, serving as an Fe/S cluster ligand has not yet been explored. To fully understand the consequences of this Gly208Cys replacement, complementary substitutions at the Fe/S cluster-binding pocket for native and Gly208Cys NFU1 were made, along with six other variants. Herein, we report the results of an investigation on the effect of these substitutions on both cluster coordination and NFU1 structure and function. The data suggest that the G208C substitution does not contribute to cluster binding. Rather, replacement of the glycine at position 208 changes the oligomerization state as a result of global structural alterations that result in the downstream effects manifest as MMDS1, but does not perturb the coordination chemistry of the Fe-S cluster. © 2017 Federation of European Biochemical Societies.

Diametrical clustering for identifying anti-correlated gene clusters.

Science.gov (United States)

Dhillon, Inderjit S; Marcotte, Edward M; Roshan, Usman

2003-09-01

Clustering genes based upon their expression patterns allows us to predict gene function. Most existing clustering algorithms cluster genes together when their expression patterns show high positive correlation. However, it has been observed that genes whose expression patterns are strongly anti-correlated can also be functionally similar. Biologically, this is not unintuitive-genes responding to the same stimuli, regardless of the nature of the response, are more likely to operate in the same pathways. We present a new diametrical clustering algorithm that explicitly identifies anti-correlated clusters of genes. Our algorithm proceeds by iteratively (i). re-partitioning the genes and (ii). computing the dominant singular vector of each gene cluster; each singular vector serving as the prototype of a 'diametric' cluster. We empirically show the effectiveness of the algorithm in identifying diametrical or anti-correlated clusters. Testing the algorithm on yeast cell cycle data, fibroblast gene expression data, and DNA microarray data from yeast mutants reveals that opposed cellular pathways can be discovered with this method. We present systems whose mRNA expression patterns, and likely their functions, oppose the yeast ribosome and proteosome, along with evidence for the inverse transcriptional regulation of a number of cellular systems.

PWR secondary water chemistry study

International Nuclear Information System (INIS)

Pearl, W.L.; Sawochka, S.G.

1977-02-01

Several types of corrosion damage are currently chronic problems in PWR recirculating steam generators. One probable cause of damage is a local high concentration of an aggressive chemical even though only trace levels are present in feedwater. A wide variety of trace chemicals can find their way into feedwater, depending on the sources of condenser cooling water and the specific feedwater treatment. In February 1975, Nuclear Water and Waste Technology Corporation (NWT), was contracted to characterize secondary system water chemistry at five operating PWRs. Plants were selected to allow effects of cooling water chemistry and operating history on steam generator corrosion to be evaluated. Calvert Cliffs 1, Prairie Island 1 and 2, Surry 2, and Turkey Point 4 were monitored during the program. Results to date in the following areas are summarized: (1) plant chemistry variations during normal operation, transients, and shutdowns; (2) effects of condenser leakage on steam generator chemistry; (3) corrosion product transport during all phases of operation; (4) analytical prediction of chemistry in local areas from bulk water chemistry measurements; and (5) correlation of corrosion damage to chemistry variation

Partitional clustering algorithms

CERN Document Server

2015-01-01

This book summarizes the state-of-the-art in partitional clustering. Clustering, the unsupervised classification of patterns into groups, is one of the most important tasks in exploratory data analysis. Primary goals of clustering include gaining insight into, classifying, and compressing data. Clustering has a long and rich history that spans a variety of scientific disciplines including anthropology, biology, medicine, psychology, statistics, mathematics, engineering, and computer science. As a result, numerous clustering algorithms have been proposed since the early 1950s. Among these algorithms, partitional (nonhierarchical) ones have found many applications, especially in engineering and computer science. This book provides coverage of consensus clustering, constrained clustering, large scale and/or high dimensional clustering, cluster validity, cluster visualization, and applications of clustering. Examines clustering as it applies to large and/or high-dimensional data sets commonly encountered in reali...

Analytical chemistry

Energy Technology Data Exchange (ETDEWEB)

Chae, Myeong Hu; Lee, Hu Jun; Kim, Ha Seok

1989-02-15

This book give explanations on analytical chemistry with ten chapters, which deal with development of analytical chemistry, the theory of error with definition and classification, sample and treatment gravimetry on general process of gravimetry in aqueous solution and non-aqueous solution, precipitation titration about precipitation reaction and types, complexometry with summary and complex compound, oxidation-reduction equilibrium on electrode potential and potentiometric titration, solvent extraction and chromatograph and experiment with basic operation for chemical experiment.

Analytical chemistry

International Nuclear Information System (INIS)

Chae, Myeong Hu; Lee, Hu Jun; Kim, Ha Seok

1989-02-01

This book give explanations on analytical chemistry with ten chapters, which deal with development of analytical chemistry, the theory of error with definition and classification, sample and treatment gravimetry on general process of gravimetry in aqueous solution and non-aqueous solution, precipitation titration about precipitation reaction and types, complexometry with summary and complex compound, oxidation-reduction equilibrium on electrode potential and potentiometric titration, solvent extraction and chromatograph and experiment with basic operation for chemical experiment.

Life's Biological Chemistry: A Destiny or Destination Starting from Prebiotic Chemistry?

Science.gov (United States)

Krishnamurthy, Ramanarayanan

2018-06-05

Research into understanding the origins -and evolution- of life has long been dominated by the concept of taking clues from extant biology and extrapolating its molecules and pathways backwards in time. This approach has also guided the search for solutions to the problem of how contemporary biomolecules would have arisen directly from prebiotic chemistry on early earth. However, the continuing difficulties in finding universally convincing solutions in connecting prebiotic chemistry to biological chemistry should give us pause, and prompt us to rethink this concept of treating extant life's chemical processes as the sole end goal and, therefore, focusing only -and implicitly- on the respective extant chemical building blocks. Rather, it may be worthwhile "to set aside the goal" and begin with what would have been plausible prebiotic reaction mixtures (which may have no obvious or direct connection to life's chemical building blocks and processes) - and allow their chemistries and interactions, under different geochemical constraints, to guide and illuminate as to what processes and systems can emerge. Such a conceptual approach gives rise to the prospect that chemistry of life-as-we-know-it is not the only result (not a "destiny"), but one that has emerged among many potential possibilities (a "destination"). This postulate, in turn, could impact the way we think about chemical signatures and criteria used in the search for alternative and extraterrestrial "life". As a bonus, we may discover the chemistries and pathways naturally that led to the emergence of life as we know it. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Chemistry for Whom? Gender Awareness in Teaching and Learning Chemistry

Science.gov (United States)

Andersson, Kristina

2017-01-01

Marie Ståhl and Anita Hussénius have defined what discourses dominate national tests in chemistry for Grade 9 in Sweden by using feminist, critical didactic perspectives. This response seeks to expand the results in Ståhl and Hussénius's article "Chemistry inside an epistemological community box!--Discursive exclusions and inclusions in the…

Young Star Cluster Found Aglow With Mysterious X-Ray Cloud

Science.gov (United States)

2002-12-01

A mysterious cloud of high-energy electrons enveloping a young cluster of stars has been discovered by astronomers using NASA's Chandra X-ray Observatory. These extremely high-energy particles could cause dramatic changes in the chemistry of the disks that will eventually form planets around stars in the cluster. Known as RCW 38, the star cluster covers a region about 5 light years across. It contains thousands of stars formed less than a million years ago and appears to be forming new stars even today. The crowded environment of a star cluster is thought to be conducive to the production of hot gas, but not high-energy particles. Such particles are typically produced by exploding stars, or in the strong magnetic fields around neutron stars or black holes, none of which is evident in RCW 38. "The RCW 38 observation doesn't agree with the conventional picture," said Scott Wolk of the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA, lead author of an Astrophysical Journal Letters paper describing the Chandra observation. "The data show that somehow extremely high-energy electrons are being produced there, although it is not clear how." RCW 38 RCW 38 X-ray, Radio, Infrared Composite Electrons accelerated to energies of trillions of volts are required to account for the observed X-ray spectrum of the gas cloud surrounding the ensemble of stars, which shows an excess of high-energy X-rays. As these electrons move in the magnetic field that threads the cluster, they produce X-rays. One possible origin for the high-energy electrons is a previously undetected supernova that occurred in the cluster. Although direct evidence for the supernova could have faded away thousands of years ago, a shock wave or a rapidly rotating neutron star produced by the outburst could be acting in concert with stellar winds to produce the high-energy electrons. "Regardless of the origin of the energetic electrons," said Wolk, "their presence would change the chemistry of proto

Reaction-Map of Organic Chemistry

Science.gov (United States)

Murov, Steven

2007-01-01

The Reaction-Map of Organic Chemistry lists all the most commonly studied reactions in organic chemistry on one page. The discussed Reaction-Map will act as another learning aide for the students, making the study of organic chemistry much easier.

Chemistry and Nanoscience Research | NREL

Science.gov (United States)

Chemistry and Nanoscience Center at NREL investigates materials and processes for converting renewable and new technologies. NREL's primary research in the chemistry and nanoscience center includes the Electrochemical Engineering and Materials Chemistry Providing a knowledge base in materials science covering

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

Renato S. Bastos; Universidade Federal do Rio de Janeiro; Bárbara V. da Silva; Universidade Federal do Rio de Janeiro; Angelo C. Pinto; Universidade Federal do Rio de Janeiro

2009-01-01

Neste artigo apresentamos as publicações brasileiras, os pesquisadores envolvidos, a contribuição por estado da federação e as principais doenças estudadas no período de 1998 a 2008 nas revistas Journal of Medicinal Chemistry, Bioorganic and Medicinal Chemistry, Bioorganic and Medicinal Chemistry Letters e European Journal of Medicinal Chemistry.  DOI: 10.5935/1984-6835.20090009  In this article we present the Brazilian publications, the research groups involved, the contributions per st...

Turkish Chemistry Teachers' Views about Secondary School Chemistry Curriculum: A Perspective from Environmental Education

Science.gov (United States)

Icoz, Omer Faruk

2015-01-01

Teachers' views about environmental education (EE) have been regarded as one of the most important concerns in education for sustainability. In secondary school chemistry curriculum, there are several subjects about EE embedded in the chemistry subjects in Turkey. This study explores three chemistry teachers' views about to what extent the…

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

Titanocene sulfide chemistry

Czech Academy of Sciences Publication Activity Database

Horáček, Michal

2016-01-01

Roč. 314, MAY 2016 (2016), s. 83-102 ISSN 0010-8545 R&D Projects: GA ČR(CZ) GAP207/12/2368 Institutional support: RVO:61388955 Keywords : titanocene sulfide chemistry * photolysis * titanocene hydrosulfides Ti-(SH)n Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 13.324, year: 2016

Chemistry and Biology

Science.gov (United States)

Wigston, David L.

1970-01-01

Discusses the relationship between chemisty and biology in the science curriculum. Points out the differences in perception of the disciplines, which the physical scientists favoring reductionism. Suggests that biology departments offer a special course for chemistry students, just as the chemistry departments have done for biology students.…

Multi-site reactivity: reduction of six equivalents of nitrite to give an Fe6(NO)6 cluster with a dramatically expanded octahedral core.

Science.gov (United States)

Harris, T David; Betley, Theodore A

2011-09-07

Reaction of NO(2)(-) with the octahedral cluster ((H)L)(2)Fe(6) in the presence of a proton source affords the hexanitrosyl cluster ((H)L)(2)Fe(6)(NO)(6). This species forms via a proton-induced reduction of six nitrite molecules per cluster, utilizing each site available on the polynuclear core. Formation of the hexanitrosyl cluster is accompanied by a near 2-fold expansion of the ((H)L)(2)Fe(6) core volume, where intracore Fe-Fe interactions are overcome by strong π-bonding between Fe centers and NO ligands. A core volume of this magnitude is rare in octahedral metal clusters not supported by interstitial atoms. Moreover, the structural flexibility afforded by the ((H)L)(2)Fe(6) platform highlights the potential for other reaction chemistry involving species with metal-ligand multiple bonds. Carrying out the reaction of the cluster [((H)L)(2)Fe(6)(NCMe)(6)](4+) with nitrite in the absence of a proton source serves to forestall the nitrite reduction and enables clean isolation of the intermediate hexanitro cluster [((H)L)(2)Fe(6)(NO(2))(6)](2-).

Understanding the Impact of a General Chemistry Course on Students' Transition to Organic Chemistry

Science.gov (United States)

Collins-Webb, Alexandra; Jeffery, Kathleen A.; Sweeder, Ryan D.

2016-01-01

The move from general chemistry to organic chemistry can be a challenge for students as it often involves a transition from quantitatively-oriented to mechanistically-oriented thinking. This study found that the design of the general chemistry course can change the student experience of this transition as assessed by a reflective survey. The…

Brain oscillation and connectivity during a chemistry visual working memory task.

Science.gov (United States)

Huang, Li-Yu; She, Hsiao-Ching; Chou, Wen-Chi; Chuang, Ming-Hua; Duann, Jeng-Ren; Jung, Tzyy-Ping

2013-11-01

Many studies have reported that frontal theta and posterior alpha activities are associated with working memory tasks. However, fewer studies have focused on examining whether or not the frontal alpha or posterior theta can play a role in the working memory task. This study investigates electroencephalography (EEG) dynamics and connectivity among different brain regions' theta and alpha oscillations. The EEG was collected from undergraduate students (n = 64) while they were performing a Sternberg-like working memory task involving chemistry concepts. The results showed that the frontal midline cluster exhibited sustained theta augmentation across the periods of stimulus presentations, maintenance, and probe presentation, suggesting that the frontal midline theta might associate with facilitating the central execute function to maintain information in the working memory. Study of the central parietal and the occipital clusters revealed a sequence of theta augmentation followed by alpha suppression at constant intervals after the onset of stimulus and probe presentations, suggesting that the posterior theta might be associated with sensory processing, theta gating, or stimulus selection. It further suggests that the posterior alpha event-related de-synchronization (ERD) might be linked to direct information flow into and out of the long-term memory (LTM) and precede stimulus recognition. An alternating phasic alpha event-related synchronization (ERS) and ERD following the 1st stimulus and probe presentations were observed at the occipital cluster, in which alpha ERS might be linked to the inhibition of irrelevant information. © 2013.

Mathematical problems for chemistry students

CERN Document Server

Pota, Gyorgy

2011-01-01

Mathematical Problems for Chemistry Students has been compiled and written (a) to help chemistrystudents in their mathematical studies by providing them with mathematical problems really occurring in chemistry (b) to help practising chemists to activate their applied mathematical skills and (c) to introduce students and specialistsof the chemistry-related fields (physicists, mathematicians, biologists, etc.) intothe world of the chemical applications.Some problems of the collection are mathematical reformulations of those in the standard textbooks of chemistry, others we

42 CFR 493.839 - Condition: Chemistry.

Science.gov (United States)

2010-10-01

... 42 Public Health 5 2010-10-01 2010-10-01 false Condition: Chemistry. 493.839 Section 493.839... These Tests § 493.839 Condition: Chemistry. The specialty of chemistry includes for the purposes of proficiency testing the subspecialties of routine chemistry, endocrinology, and toxicology. ...

Virtually going green: The role of quantum computational chemistry in reducing pollution and toxicity in chemistry

Science.gov (United States)

Stevens, Jonathan

2017-07-01

Continuing advances in computational chemistry has permitted quantum mechanical calculation to assist in research in green chemistry and to contribute to the greening of chemical practice. Presented here are recent examples illustrating the contribution of computational quantum chemistry to green chemistry, including the possibility of using computation as a green alternative to experiments, but also illustrating contributions to greener catalysis and the search for greener solvents. Examples of applications of computation to ambitious projects for green synthetic chemistry using carbon dioxide are also presented.

The 2013 Clusters, Nanocrystals & Nanostructures Gordon Research Conference/Gordon Research Seminar

Energy Technology Data Exchange (ETDEWEB)

Krauss, Todd D. [University of Rochester

2014-11-25

The fundamental properties of small particles and their potential for groundbreaking applications are among the most exciting areas of study in modern physics, chemistry, and materials science. The Clusters, Nanocrystals & Nanostructures Gordon ResearchConference and Gordon Research Seminar synthesize contributions from these inter-related fields that reflect the pivotal role of nano-particles at the interface between these disciplines. Size-dependent optical, electronic, magnetic and catalytic properties offer prospects for applications in many fields, and possible solutions for many of the grand challenges facing energy generation, consumption, delivery, and storage in the 21st century. The goal of the 2013 Clusters, Nanocrystals & Nanostructures Gordon Research Conference and Gordon Research Seminar is to continue the historical interdisciplinary tradition of this series and discuss the most recent advances, basic scientific questions, and emerging applications of clusters, nanocrystals, and nanostructures. The Clusters, Nanocrystals & Nanostructures GRC/GRS traditionally brings together the leading scientific groups that have made significant recent advances in one or more fundamental nanoscience or nanotechnology areas. Broad interests of the DOE BES and Solar Photochemistry Program addressed by this meeting include the areas of solar energy to fuels conversion, new photovoltaic systems, fundamental characterization of nanomaterials, magnetism, catalysis, and quantum physics. The vast majority of speakers and attendees will address either directly the topic of nanotechnology for photoinduced charge transfer, charge transport, and catalysis, or will have made significant contributions to related areas that will impact these fields indirectly. These topics have direct relevance to the mission of the DOE BES since it is this cutting-edge basic science that underpins our energy future.

Chemistry Cube Game - Exploring Basic Principles of Chemistry by Turning Cubes.

Science.gov (United States)

Müller, Markus T

2018-02-01

The Chemistry Cube Game invites students at secondary school level 1 and 2 to explore basic concepts of chemistry in a playful way, either as individuals or in teams. It consists of 15 different cubes, 9 cubes for different acids, their corresponding bases and precursors, and 6 cubes for different reducing and oxidising agents. The cubes can be rotated in those directions indicated. Each 'allowed' vertical or horizontal rotation of 90° stands for a chemical reaction or a physical transition. Two different games and playing modes are presented here: First, redox chemistry is introduced for the formation of salts from elementary metals and non-metals. Second, the speciation of acids and bases at different pH-values is shown. The cubes can be also used for games about environmental chemistry such as the carbon and sulphur cycle, covering the topic of acid rain, or the nitrogen cycle including ammoniac synthesis, nitrification and de-nitrification.

SPECIAL ISSUE DEDICATED TO THE 10TH ANNIVERSARY OF THE CHEMISTRY JOURNAL OF MOLDOVA. GENERAL, INDUSTRIAL AND ECOLOGICAL CHEMISTRY

OpenAIRE

Gheorghe DUCA

2016-01-01

Ten years ago, in 2006, CHEMISTRY JOURNAL OF MOLDOVA. General, Industrial and Ecological Chemistry was founded by the Institute of Chemistry of Academy of Sciences of Moldova and Moldova State University. Chemistry Journal of Moldova is an open access, international indexed and peer-reviewed journal that publishes papers of high quality containing original results in the areas of Chemical Sciences, such as analytical chemistry, ecological chemistry, food chemistry, industrial chem...

Cluster Matters

DEFF Research Database (Denmark)

Gulati, Mukesh; Lund-Thomsen, Peter; Suresh, Sangeetha

2018-01-01

sell their products successfully in international markets, but there is also an increasingly large consumer base within India. Indeed, Indian industrial clusters have contributed to a substantial part of this growth process, and there are several hundred registered clusters within the country...... of this handbook, which focuses on the role of CSR in MSMEs. Hence we contribute to the literature on CSR in industrial clusters and specifically CSR in Indian industrial clusters by investigating the drivers of CSR in India’s industrial clusters....

Weighted Clustering

DEFF Research Database (Denmark)

Ackerman, Margareta; Ben-David, Shai; Branzei, Simina

2012-01-01

We investigate a natural generalization of the classical clustering problem, considering clustering tasks in which different instances may have different weights.We conduct the first extensive theoretical analysis on the influence of weighted data on standard clustering algorithms in both...... the partitional and hierarchical settings, characterizing the conditions under which algorithms react to weights. Extending a recent framework for clustering algorithm selection, we propose intuitive properties that would allow users to choose between clustering algorithms in the weighted setting and classify...

In the land of the dinosaurs, how to survive experience with building of midrange computing cluster

Energy Technology Data Exchange (ETDEWEB)

Chevel, A E [Petersburg Nuclear Physics Institute, Gatchina (Russian Federation); Lauret, J [SUNY at Stony Brook (United States)

2001-07-01

The authors discuss how to put into operation a midrange computing cluster for the Nuclear Chemistry Group (NCG) of the Stage University of New York at STONY Brook (SUNY-SB). The NCG is part and one of the collaborators within the RHIC/Phenix experiment located at the Brookhaven National Laboratory (BNL). The Phenix detector system produces about half a PB (or 500 TB) of data a year and our goal was to provide to this remote collaborating facility the means to be part of the analysis process. The computing installation was put into operation at the beginning of the year 2000. The cluster consists of 32 peripheral machines running under Linux and central server Alpha 4100 under Digital Unix 4.0f (formally True Unix 64). The realization process is under discussion.

In the land of the dinosaurs, how to survive experience with building of midrange computing cluster

International Nuclear Information System (INIS)

Chevel, A.E.; Lauret, J.

2001-01-01

The authors discuss how to put into operation a midrange computing cluster for the Nuclear Chemistry Group (NCG) of the Stage University of New York at STONY Brook (SUNY-SB). The NCG is part and one of the collaborators within the RHIC/Phenix experiment located at the Brookhaven National Laboratory (BNL). The Phenix detector system produces about half a PB (or 500 TB) of data a year and our goal was to provide to this remote collaborating facility the means to be part of the analysis process. The computing installation was put into operation at the beginning of the year 2000. The cluster consists of 32 peripheral machines running under Linux and central server Alpha 4100 under Digital Unix 4.0f (formally True Unix 64). The realization process is under discussion

Atmospheric chemistry and climate

OpenAIRE

Satheesh, SK

2012-01-01

Atmospheric chemistry is a branch of atmospheric science where major focus is the composition of the Earth's atmosphere. Knowledge of atmospheric composition is essential due to its interaction with (solar and terrestrial) radiation and interactions of atmospheric species (gaseous and particulate matter) with living organisms. Since atmospheric chemistry covers a vast range of topics, in this article the focus is on the chemistry of atmospheric aerosols with special emphasis on the Indian reg...

Aqueous Solution Chemistry of Plutonium

Energy Technology Data Exchange (ETDEWEB)

Clark, David L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2014-01-28

Things I have learned working with plutonium: Chemistry of plutonium is complex; Redox equilibria make Pu solution chemistry particularly challenging in the absence of complexing ligands; Understanding this behavior is key to successful Pu chemistry experiments; There is no suitable chemical analog for plutonium.

Support Policies in Clusters: Prioritization of Support Needs by Cluster Members According to Cluster Life Cycle

Directory of Open Access Journals (Sweden)

Gulcin Salıngan

2012-07-01

Full Text Available Economic development has always been a moving target. Both the national and local governments have been facing the challenge of implementing the effective and efficient economic policy and program in order to best utilize their limited resources. One of the recent approaches in this area is called cluster-based economic analysis and strategy development. This study reviews key literature and some of the cluster based economic policies adopted by different governments. Based on this review, it proposes “the cluster life cycle” as a determining factor to identify the support requirements of clusters. A survey, designed based on literature review of International Cluster support programs, was conducted with 30 participants from 3 clusters with different maturity stage. This paper discusses the results of this study conducted among the cluster members in Eskişehir- Bilecik-Kütahya Region in Turkey on the requirement of the support to foster the development of related clusters.

Sign me up! Determining motivation for high school chemistry students enrolling in a second year chemistry course

Science.gov (United States)

Camarena, Nilda N.

A sample of 108 Pre-AP Chemistry students in Texas participated in a study to determine motivational factors for enrolling in AP Chemistry and University Chemistry. The factors measured were academic attitude, perceptions of chemistry, confidence level in chemistry, and expectations/experiences in the chemistry class. Students completed two questionnaires, one at the beginning of the year and one at the end. Four high school campuses from two school districts in Texas participated. Two campuses were traditional high schools and two were smaller magnet schools. The results from this study are able to confirm that there are definite correlations between academic attitudes, perceptions, confidence level, and experiences and a student's plans to enroll in AP and University Chemistry. The type of school as well as the student's gender seemed to have an influence on a student's plan to enroll in a second year of chemistry.

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

Puzzling through General Chemistry: A Light-Hearted Approach to Engaging Students with Chemistry Content

Science.gov (United States)

Boyd, Susan L.

2007-01-01

Several puzzles are designed to be used by chemistry students as learning tools and teach them basic chemical concepts. The topics of the puzzles are based on the chapters from Chemistry, The Central Science used in general chemistry course and the puzzles are in various forms like crosswords, word searches, number searches, puzzles based on…

Chemistry in South Africa - yesterday, today and tomorrow

International Nuclear Information System (INIS)

1987-01-01

The jubilee convention of the South African Chemical Institute covered the development of chemistry in South Africa. Specialists in the field of chemistry covered topics with reference to organic chemistry, extraction metallurgy, analytical chemistry, mass spectroscopy, instrumentation, theoretical chemistry, physical chemistry, chromatography, industrial chemistry and solid state chemistry

Medicinal electrochemistry: integration of electrochemistry, medicinal chemistry and computational chemistry.

Science.gov (United States)

Almeida, M O; Maltarollo, V G; de Toledo, R A; Shim, H; Santos, M C; Honorio, K M

2014-01-01

Over the last centuries, there were many important discoveries in medicine that were crucial for gaining a better understanding of several physiological processes. Molecular modelling techniques are powerful tools that have been successfully used to analyse and interface medicinal chemistry studies with electrochemical experimental results. This special combination can help to comprehend medicinal chemistry problems, such as predicting biological activity and understanding drug action mechanisms. Electrochemistry has provided better comprehension of biological reactions and, as a result of many technological improvements, the combination of electrochemical techniques and biosensors has become an appealing choice for pharmaceutical and biomedical analyses. Therefore, this review will briefly outline the present scope and future advances related to the integration of electrochemical and medicinal chemistry approaches based on various applications from recent studies.

Effective Chemistry Communication in Informal Environments

Science.gov (United States)

National Academies Press, 2016

2016-01-01

Chemistry plays a critical role in daily life, impacting areas such as medicine and health, consumer products, energy production, the ecosystem, and many other areas. Communicating about chemistry in informal environments has the potential to raise public interest and understanding of chemistry around the world. However, the chemistry community…

Growing your green chemistry mindset

Science.gov (United States)

Kosmas, Steven

2017-08-01

The purpose of this article is not to delineate the steps to move across the continuum to being a greener chemist, but to analyse the cognitive processes involved in fostering a green chemistry growth mindset (GCGM) [Dweck C. (2006) Mindset: The New Psychology of Success. New York, NY: Ballatine]. The focus is on changing the mindset, which inevitably will lead to a more mindful approach to chemistry practices before the laboratory begins. A green chemistry fixed mindset (GCFM) is closed to making improvements, since the attitude is that the techniques and processes in the laboratory are already employing a green chemistry mindset [Dweck C. (2006) Mindset: The New Psychology of Success. New York, NY: Ballatine]. The problem with the GCFM is that it precludes the possibility of making improvements. However, the GCGM employs a continuous, intentional focus on the attitude towards green chemistry, with the ultimate goal being a change in chemistry practices that is greener. The focus of this article will be on the GCGM.

Clusters and how to make it work : toolkit for cluster strategy

NARCIS (Netherlands)

Manickam, Anu; van Berkel, Karel

2013-01-01

Clusters are the magic answer to regional economic development. Firms in clusters are more innovative; cluster policy dominates EU policy; ‘top-sectors’ and excellence are the choice of national policy makers; clusters are ‘in’. But, clusters are complex, clusters are ‘messy’; there is no clear

Analytical chemistry

International Nuclear Information System (INIS)

Choi, Jae Seong

1993-02-01

This book is comprised of nineteen chapters, which describes introduction of analytical chemistry, experimental error and statistics, chemistry equilibrium and solubility, gravimetric analysis with mechanism of precipitation, range and calculation of the result, volume analysis on general principle, sedimentation method on types and titration curve, acid base balance, acid base titration curve, complex and firing reaction, introduction of chemical electro analysis, acid-base titration curve, electrode and potentiometry, electrolysis and conductometry, voltammetry and polarographic spectrophotometry, atomic spectrometry, solvent extraction, chromatograph and experiments.

Analytical chemistry

Energy Technology Data Exchange (ETDEWEB)

Choi, Jae Seong

1993-02-15

This book is comprised of nineteen chapters, which describes introduction of analytical chemistry, experimental error and statistics, chemistry equilibrium and solubility, gravimetric analysis with mechanism of precipitation, range and calculation of the result, volume analysis on general principle, sedimentation method on types and titration curve, acid base balance, acid base titration curve, complex and firing reaction, introduction of chemical electro analysis, acid-base titration curve, electrode and potentiometry, electrolysis and conductometry, voltammetry and polarographic spectrophotometry, atomic spectrometry, solvent extraction, chromatograph and experiments.

Chemistry of the elements

International Nuclear Information System (INIS)

Greenwood, N.N.; Earnshaw, A.

1984-01-01

This textbook presents an account of the chemistry of the elements for both undergraduate and postgraduate students. It covers not only the 'inorganic' chemistry of the elements, but also analytical, theoretical, industrial, organometallic;, bio-inorganic and other areas of chemistry which apply. The following elements of special nuclear interest are included: Rb, Cs, Fr, Sr, Ba, Ra, Po, At, Rn, Sc, Y, Zr, Hf, V, Nb, Ta, Mo, Tc, Ru, the Lanthanide Elements, the Actinide Elements. (U.K.)

Polymer chemistry (revised edition)

International Nuclear Information System (INIS)

Kim, Jae Mum

1987-02-01

This book deals with polymer chemistry, which is divided into fourteen chapters. The contents of this book are development of polymer chemistry, conception of polymer, measurement of polymer chemistry, conception of polymer, measurement of polymer, molecule structure of polymer, thermal prosperities of solid polymer, basic theory of polymerization, radical polymerization, ion polymerization, radical polymerization, copolymerization, polymerization by step-reaction, polymer reaction, crown polymer and inorganic polymer on classification and process of creation such as polymeric sulfur and carbon fiber.

42 CFR 493.929 - Chemistry.

Science.gov (United States)

2010-10-01

... 42 Public Health 5 2010-10-01 2010-10-01 false Chemistry. 493.929 Section 493.929 Public Health... Proficiency Testing Programs by Specialty and Subspecialty § 493.929 Chemistry. The subspecialties under the specialty of chemistry for which a proficiency testing program may offer proficiency testing are routine...

The physical basis of chemistry

CERN Document Server

Warren, Warren S

2000-01-01

If the text you're using for general chemistry seems to lack sufficient mathematics and physics in its presentation of classical mechanics, molecular structure, and statistics, this complementary science series title may be just what you're looking for. Written for the advanced lower-division undergraduate chemistry course, The Physical Basis of Chemistry, Second Edition, offers students an opportunity to understand and enrich the understanding of physical chemistry with some quantum mechanics, the Boltzmann distribution, and spectroscopy. Posed and answered are questions concerning eve

Radiation chemistry; principles and applications

International Nuclear Information System (INIS)

Aziz, F.; Rodgers, M.A.J.

1994-01-01

The book attempts to present those fields of radiation chemistry which depend on the principles of radiation chemistry. The first four chapters are some prelude about radiation chemistry principles with respect to how ionizing radiation interacts with matter, and primary results from these interactions and, which kinetic laws are followed by these primary interactions and which equipment for qualitative studies is necessary. Following chapters included principles fields of radiation chemistry. The last six chapters discussed of principle of chemistry from physical and chemical point of view. In this connection the fundamentals of radiation on biological system is emphasised. On one hand, the importance of it for hygiene and safety as neoplasms therapy is discussed. on the other hand, its industrial importance is presented

Iridium Clusters Encapsulated in Carbon Nanospheres as Nanocatalysts for Methylation of (Bio)Alcohols.

Science.gov (United States)

Liu, Qiang; Xu, Guoqiang; Wang, Zhendong; Liu, Xiaoran; Wang, Xicheng; Dong, Linlin; Mu, Xindong; Liu, Huizhou

2017-12-08

C-H methylation is an attractive chemical transformation for C-C bonds construction in organic chemistry, yet efficient methylation of readily available (bio)alcohols in water using methanol as sustainable C1 feedstock is limited. Herein, iridium nanocatalysts encapsulated in yolk-shell-structured mesoporous carbon nanospheres (Ir@YSMCNs) were synthesized for this transformation. Monodispersed Ir clusters (ca. 1.0 nm) were encapsulated in situ and spatially isolated within YSMCNs by a silica-assisted sol-gel emulsion strategy. A selection of (bio)alcohols (19 examples) was selectively methylated in aqueous phase with good-to-high yields over the developed Ir@YSMCNs. The improved catalytic efficiencies in terms of activity and selectivity together with the good stability and recyclability were contributable to the ultrasmall Ir clusters with oxidation chemical state as a consequence of the confinement effect of YSMCNs with interconnected nanostructures. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Technetium Chemistry in HLW

International Nuclear Information System (INIS)

Hess, Nancy J.; Felmy, Andrew R.; Rosso, Kevin M.; Xia Yuanxian

2005-01-01

Tc contamination is found within the DOE complex at those sites whose mission involved extraction of plutonium from irradiated uranium fuel or isotopic enrichment of uranium. At the Hanford Site, chemical separations and extraction processes generated large amounts of high level and transuranic wastes that are currently stored in underground tanks. The waste from these extraction processes is currently stored in underground High Level Waste (HLW) tanks. However, the chemistry of the HLW in any given tank is greatly complicated by repeated efforts to reduce volume and recover isotopes. These processes ultimately resulted in mixing of waste streams from different processes. As a result, the chemistry and the fate of Tc in HLW tanks are not well understood. This lack of understanding has been made evident in the failed efforts to leach Tc from sludge and to remove Tc from supernatants prior to immobilization. Although recent interest in Tc chemistry has shifted from pretreatment chemistry to waste residuals, both needs are served by a fundamental understanding of Tc chemistry

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

International Nuclear Information System (INIS)

Legrand, Francois

2015-01-01

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

Contribution from philosophy of chemistry to chemistry education: In a case of ionic liquids as technochemistry

Science.gov (United States)

Mudzakir, Ahmad; Hernani, Widhiyanti, Tuszie; Sudrajat, Devi Pratiwi

2017-08-01

Traditional chemistry education is commonly handing down of concepts, principles, and theories, such as mechanical properties, the relationship between structure and properties as well as chemical structure and chemical bonding theory, to students without engaging them in the processes of chemical inquiry. This practice leads to the lack of opportunity for the students to construct an appropriate understanding of these concepts, principles, and theories. Students are also rarely facilitated in modeling the structure and function of matter themselves. This situation shows that the philosophy of chemistry has not received as much attention from chemistry educators. The main idea of this paper is to embed philosophy of chemistry through the implementation of technochemistry in chemistry education. One of the most interesting and rapidly developing areas of modern chemistry, technologies and engineering is Ionic Liquids (ILs) as an emerging knowledge on technochemistry which can be applied to chemistry education. The developments between academic researchers and industrial developments in the ILs area are conducted in parallel. In order to overcome the existing problems of scientific development in chemistry education, the science and technology of ILs can be used for reconceptualizing the teaching and learning of chemistry to embrace the epistemology in chemistry. This study promises a potential contribution by philosophy of chemistry. The main objectives of this study are to develop: (i) a perspective based on philosophy of science considerations (rational reconstruction) in order to understand ionic liquids and (ii) teaching materials that can be used to enhance pre-service teacher's view of nature of science and technology (VNOST). The method used in the study is analytical-descriptive (elementarization), i.e. the first step in the model of educational reconstruction (MER). This study concludes that the development of the concepts and their applications of ionic

Determination of atomic cluster structure with cluster fusion algorithm

DEFF Research Database (Denmark)

Obolensky, Oleg I.; Solov'yov, Ilia; Solov'yov, Andrey V.

2005-01-01

We report an efficient scheme of global optimization, called cluster fusion algorithm, which has proved its reliability and high efficiency in determination of the structure of various atomic clusters.......We report an efficient scheme of global optimization, called cluster fusion algorithm, which has proved its reliability and high efficiency in determination of the structure of various atomic clusters....

Large-Scale Multi-Dimensional Document Clustering on GPU Clusters

Energy Technology Data Exchange (ETDEWEB)

Cui, Xiaohui [ORNL; Mueller, Frank [North Carolina State University; Zhang, Yongpeng [ORNL; Potok, Thomas E [ORNL

2010-01-01

Document clustering plays an important role in data mining systems. Recently, a flocking-based document clustering algorithm has been proposed to solve the problem through simulation resembling the flocking behavior of birds in nature. This method is superior to other clustering algorithms, including k-means, in the sense that the outcome is not sensitive to the initial state. One limitation of this approach is that the algorithmic complexity is inherently quadratic in the number of documents. As a result, execution time becomes a bottleneck with large number of documents. In this paper, we assess the benefits of exploiting the computational power of Beowulf-like clusters equipped with contemporary Graphics Processing Units (GPUs) as a means to significantly reduce the runtime of flocking-based document clustering. Our framework scales up to over one million documents processed simultaneously in a sixteennode GPU cluster. Results are also compared to a four-node cluster with higher-end GPUs. On these clusters, we observe 30X-50X speedups, which demonstrates the potential of GPU clusters to efficiently solve massive data mining problems. Such speedups combined with the scalability potential and accelerator-based parallelization are unique in the domain of document-based data mining, to the best of our knowledge.

Membership determination of open clusters based on a spectral clustering method

Science.gov (United States)

Gao, Xin-Hua

2018-06-01

We present a spectral clustering (SC) method aimed at segregating reliable members of open clusters in multi-dimensional space. The SC method is a non-parametric clustering technique that performs cluster division using eigenvectors of the similarity matrix; no prior knowledge of the clusters is required. This method is more flexible in dealing with multi-dimensional data compared to other methods of membership determination. We use this method to segregate the cluster members of five open clusters (Hyades, Coma Ber, Pleiades, Praesepe, and NGC 188) in five-dimensional space; fairly clean cluster members are obtained. We find that the SC method can capture a small number of cluster members (weak signal) from a large number of field stars (heavy noise). Based on these cluster members, we compute the mean proper motions and distances for the Hyades, Coma Ber, Pleiades, and Praesepe clusters, and our results are in general quite consistent with the results derived by other authors. The test results indicate that the SC method is highly suitable for segregating cluster members of open clusters based on high-precision multi-dimensional astrometric data such as Gaia data.

Division of Analytical Chemistry, 1998

DEFF Research Database (Denmark)

Hansen, Elo Harald

1999-01-01

The article recounts the 1998 activities of the Division of Analytical Chemistry (DAC- formerly the Working Party on Analytical Chemistry, WPAC), which body is a division of the Federation of European Chemical Societies (FECS). Elo Harald Hansen is the Danish delegate, representing The Danish...... Chemical Society/The Society for Analytical Chemistry....

Ferromagnetic bond of Li{sub 10} cluster: An alternative approach in terms of effective ferromagnetic sites

Energy Technology Data Exchange (ETDEWEB)

Donoso, Roberto; Fuentealba, Patricio, E-mail: pfuentea@hotmail.es, E-mail: cardena@macul.ciencias.uchile.cl; Cárdenas, Carlos, E-mail: pfuentea@hotmail.es, E-mail: cardena@macul.ciencias.uchile.cl [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Centro para el Desarrollo de la Nanociencia y la Nanotecnología (CEDENNA), Avda. Ecuador 3493, Santiago 9170124 (Chile); Rössler, Jaime [Departamento de Física, Facultad de Ciencias, Universidad de Chile, Casilla 653, Santiago (Chile); Llano-Gil, Sandra [Faculty of Engineering, Food Engineering Program, Corporación Universitaria Lasallista, Caldas, Antioquia (Colombia)

2016-09-07

In this work, a model to explain the unusual stability of atomic lithium clusters in their highest spin multiplicity is presented and used to describe the ferromagnetic bonding of high-spin Li{sub 10} and Li{sub 8} clusters. The model associates the (lack of-)fitness of Heisenberg Hamiltonian with the degree of (de-)localization of the valence electrons in the cluster. It is shown that a regular Heisenberg Hamiltonian with four coupling constants cannot fully explain the energy of the different spin states. However, a more simple model in which electrons are located not at the position of the nuclei but at the position of the attractors of the electron localization function succeeds in explaining the energy spectrum and, at the same time, explains the ferromagnetic bond found by Shaik using arguments of valence bond theory. In this way, two different points of view, one more often used in physics, the Heisenberg model, and the other in chemistry, valence bond, come to the same answer to explain those atypical bonds.

Performance Optimization of Tensor Contraction Expressions for Many Body Methods in Quantum Chemistry

International Nuclear Information System (INIS)

Hartono, Albert; Lu, Qingda; Henretty, Thomas; Krishnamoorthy, Sriram; Zhang, Huaijian; Baumgartner, Gerald; Bernholdt, David E.; Nooijen, Marcel; Pitzer, Russell M.; Ramanujam, J.; Sadayappan, Ponnuswamy

2009-01-01

Complex tensor contraction expressions arise in accurate electronic structure models in quantum chemistry, such as the coupled cluster method. This paper addresses two complementary aspects of performance optimization of such tensor contraction expressions. Transformations using algebraic properties of commutativity and associativity can be used to significantly decrease the number of arithmetic operations required for evaluation of these expressions. The identification of common subexpressions among a set of tensor contraction expressions can result in a reduction of the total number of operations required to evaluate the tensor contractions. The first part of the paper describes an effective algorithm for operation minimization with common subexpression identification and demonstrates its effectiveness on tensor contraction expressions for coupled cluster equations. The second part of the paper highlights the importance of data layout transformation in the optimization of tensor contraction computations on modern processors. A number of considerations such as minimization of cache misses and utilization of multimedia vector instructions are discussed. A library for efficient index permutation of multi-dimensional tensors is described and experimental performance data is provided that demonstrates its effectiveness.

Performance Optimization of Tensor Contraction Expressions for Many Body Methods in Quantum Chemistry

International Nuclear Information System (INIS)

Krishnamoorthy, Sriram; Bernholdt, David E.; Pitzer, R.M.; Sadayappan, Ponnuswamy

2009-01-01

Complex tensor contraction expressions arise in accurate electronic structure models in quantum chemistry, such as the coupled cluster method. This paper addresses two complementary aspects of performance optimization of such tensor contraction expressions. Transformations using algebraic properties of commutativity and associativity can be used to significantly decrease the number of arithmetic operations required for evaluation of these expressions. The identification of common subexpressions among a set of tensor contraction expressions can result in a reduction of the total number of operations required to evaluate the tensor contractions. The first part of the paper describes an effective algorithm for operation minimization with common subexpression identification and demonstrates its effectiveness on tensor contraction expressions for coupled cluster equations. The second part of the paper highlights the importance of data layout transformation in the optimization of tensor contraction computations on modern processors. A number of considerations, such as minimization of cache misses and utilization of multimedia vector instructions, are discussed. A library for efficient index permutation of multidimensional tensors is described, and experimental performance data is provided that demonstrates its effectiveness.

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)

Cluster headache

Science.gov (United States)

Histamine headache; Headache - histamine; Migrainous neuralgia; Headache - cluster; Horton's headache; Vascular headache - cluster ... Doctors do not know exactly what causes cluster headaches. They ... (chemical in the body released during an allergic response) or ...

Solid state chemistry an introduction

CERN Document Server

Smart, Lesley E

2012-01-01

""Smart and Moore are engaging writers, providing clear explanations for concepts in solid-state chemistry from the atomic/molecular perspective. The fourth edition is a welcome addition to my bookshelves. … What I like most about Solid State Chemistry is that it gives simple clear descriptions for a large number of interesting materials and correspondingly clear explanations of their applications. Solid State Chemistry could be used for a solid state textbook at the third or fourth year undergraduate level, especially for chemistry programs. It is also a useful resource for beginning graduate

Computational quantum chemistry website

International Nuclear Information System (INIS)

1997-01-01

This report contains the contents of a web page related to research on the development of quantum chemistry methods for computational thermochemistry and the application of quantum chemistry methods to problems in material chemistry and chemical sciences. Research programs highlighted include: Gaussian-2 theory; Density functional theory; Molecular sieve materials; Diamond thin-film growth from buckyball precursors; Electronic structure calculations on lithium polymer electrolytes; Long-distance electronic coupling in donor/acceptor molecules; and Computational studies of NOx reactions in radioactive waste storage

Solid state chemistry and its applications

CERN Document Server

West, Anthony R

2013-01-01

Solid State Chemistry and its Applications, 2nd Edition: Student Edition is an extensive update and sequel to the bestselling textbook Basic Solid State Chemistry, the classic text for undergraduate teaching in solid state chemistry worldwide. Solid state chemistry lies at the heart of many significant scientific advances from recent decades, including the discovery of high-temperature superconductors, new forms of carbon and countless other developments in the synthesis, characterisation and applications of inorganic materials. Looking forward, solid state chemistry will be crucial for the

Popular Science Articles for Chemistry Teaching

Directory of Open Access Journals (Sweden)

Ketevan Kupatadze

2017-07-01

Full Text Available The presented paper reviews popular science articles (these articles are published in online magazine “The Teacher” as one of the methods of chemistry teaching. It describes which didactic principles they are in line with and how this type of articles can be used in order to kindle the interest of pupils, students and generally, the readers of other specialties, in chemistry.  The articles review the main topics of inorganic/organic chemistry, biochemistry and ecological chemistry in a simple and entertaining manner. A part of the articles is about "household" chemistry. Chemical topics are related to poetry, literature, history of chemistry or simply, to fun news. The paper delineates the structure of popular science articles and the features of engaging students. It also reviews the teachers' and students' interview results about the usage of popular science articles in chemistry teaching process. The aforementioned pedagogical study revealed that the popular science articles contain useful information not only for the students of other specialties, but also for future biologists and ecologists (having chemistry as a mandatory subject at their universities. The articles are effectively used by teachers on chemistry lessons to kindle students' interest in this subject. DOI: http://dx.doi.org/10.17807/orbital.v9i3.960 

Radiation chemistry

International Nuclear Information System (INIS)

Swallow, A.J.

1983-01-01

The subject is covered in chapters, entitled: introduction (defines scope of article as dealing with the chemistry of reactive species, (e.g. excess electrons, excited states, free radicals and inorganic ions in unusual valency states) as studied using radiation with radiation chemistry in its traditional sense and with biological and industrial applications); gases; water and simple inorganic systems; aqueous metallo-organic compounds and metalloproteins; small organic molecules in aqueous solution; microheterogeneous systems; non-aqueous liquids and solutions; solids; biological macromolecules; synthetic polymers. (U.K.)

Annual report 1985 Chemistry Department

International Nuclear Information System (INIS)

1987-01-01

This annual report describes the activities carried out in 1985 by the Chemistry Department in the following fields: Chemistry, Inorganic Chemistry, Physicochemistry (Interphases, Surfaces), General Chemical Analysis, Active Materials Analysis, X Ray Fluorescence Analysis, Mass Spectroscopy (Isotopic Analysis, Instrumentation) and Optical Spectroscopy. A list of publications is enclosed. (M.E.L.) [es

The use of nuclear muprobe techniques to study the chemistry of lacustrine sediments and particles

Science.gov (United States)

Grime, G. W.; Davison, W.

1993-05-01

The Oxford SPM has been used in two novel studies of lake chemistry: (a) The distribution of dissolved iron in sediment pore waters close to the sediment/water interface has been measured using the novel technique of diffusive equilibration in a thin film (DET). In this technique, which has a spatial resolution of O stoichiometry of single particles. The particles were filtered from a depth of 14 m in Esthwaite Water in the English Lake District and handled in anoxic conditions until evacuation in the SPM sample chamber. Two distinct compositions of iron oxide were determined in clusters of about 5 μm diameter. Analysis by PIXE revealed that FeS was uniformly distributed in the particulate material and that it also contained elevated levels of Cu and Zn. This study was the first to demonstrate directly that discrete clusters of iron oxides are present in black particulate material which is commonly considered to comprise iron sulphides.

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

State-specific Brillouin-Wigner Multireference Coupled Cluster Study of the F.sub.2./sub. Molecule: Assessment of the a Posteriori Size-extensivity Correction

Czech Academy of Sciences Publication Activity Database

Pittner, Jiří; Šmydke, Jan; Čársky, Petr; Hubač, I.

2001-01-01

Roč. 547, - (2001), s. 239-244 ISSN 0166-1280 R&D Projects: GA MŠk OC D9.10; GA ČR GA203/99/D009 Institutional research plan: CEZ:AV0Z4040901 Keywords : potential curve * spectroscopic constants of F2 * multireference coupled clusters Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 0.919, year: 2001

Revealing isomerism in sodium-water clusters: Photoionization spectra of Na(H2O)n (n = 2-90)

Science.gov (United States)

Dierking, Christoph W.; Zurheide, Florian; Zeuch, Thomas; Med, Jakub; Parez, Stanislav; Slavíček, Petr

2017-06-01

Soft ionization of sodium tagged polar clusters is increasingly used as a powerful technique for sizing and characterization of small aerosols with possible application, e.g., in atmospheric chemistry or combustion science. Understanding the structure and photoionization of the sodium doped clusters is critical for such applications. In this work, we report on measurements of photoionization spectra for sodium doped water clusters containing 2-90 water molecules. While most of the previous studies focused on the ionization threshold of the Na(H2O)n clusters, we provide for the first time full photoionization spectra, including the high-energy region, which are used as reference for a comparison with theory. As reported in previous work, we have seen an initial drop of the appearance ionization energy with cluster size to values of about 3.2 eV for n electron cloud. The appearance ionization energy is determined by isomers with fully solvated sodium and a highly delocalized electron cloud, while both fully and incompletely solvated isomers with localized electron clouds can contribute to the high energy part of the photoionization spectrum. Simulations at elevated temperatures show an increased abundance of isomers with low ionization energies, an entropic effect enabling size selective infrared action spectroscopy, based on near threshold photoionization of Na(H2O)n clusters. In addition, simulations of the sodium pick-up process were carried out to study the gradual formation of the hydrated electron which is the basis of the sodium-tagging sizing.

Seeing the Chemistry around Me--Helping Students Identify the Relevance of Chemistry to Everyday Life

Science.gov (United States)

Moore, Tracy Lynn

2012-01-01

The study attempted to determine whether the use of a series of reading and response assignments decreased students' perceptions of chemistry difficulty and enhanced students' perceptions of the relevance of chemistry in their everyday lives. Informed consent volunteer students enrolled in General Chemistry II at a community college in the…

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...

Aromatic Polyketide GTRI-02 is a Previously Unidentified Product of the act Gene Cluster in Streptomyces coelicolor A3(2).

Science.gov (United States)

Wu, Changsheng; Ichinose, Koji; Choi, Young Hae; van Wezel, Gilles P

2017-07-18

The biosynthesis of aromatic polyketides derived from type II polyketide synthases (PKSs) is complex, and it is not uncommon that highly similar gene clusters give rise to diverse structural architectures. The act biosynthetic gene cluster (BGC) of the model actinomycete Streptomyces coelicolor A3(2) is an archetypal type II PKS. Here we show that the act BGC also specifies the aromatic polyketide GTRI-02 (1) and propose a mechanism for the biogenesis of its 3,4-dihydronaphthalen-1(2H)-one backbone. Polyketide 1 was also produced by Streptomyces sp. MBT76 after activation of the act-like qin gene cluster by overexpression of the pathway-specific activator. Mining of this strain also identified dehydroxy-GTRI-02 (2), which most likely originated from dehydration of 1 during the isolation process. This work shows that even extensively studied model gene clusters such as act of S. coelicolor can still produce new chemistry, offering new perspectives for drug discovery. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Creating a Context for Chemistry

Science.gov (United States)

Truman Schwartz, A.

Until relatively recently, the teaching of chemistry at the college and university level in the United States has been quite traditional and oriented primarily toward the preparation of chemists. Students not concentrating in the sciences have often been poorly served by existing courses. Chemistry in Context: Applying Chemistry to Society, a textbook for nonscience majors developed under the sponsorship of the American Chemical Society, is an effort to address the needs and interests of this audience. The book introduces the phenomena and principles of chemistry within the context of socially significant issues such as global warming, ozone depletion, alternate energy sources, nutrition, and genetic engineering. The chemistry is presented as needed to inform an understanding of the central topics, and the text features student-centered activities designed to promote critical thinking and risk-benefit analysis as well as an understanding of chemical principles. This paper summarizes the origin, development, content, pedagogy, evaluation, and influence of Chemistry in Context and considers its potential implications for other disciplines and the instruction of science majors.

Single-cluster dynamics for the random-cluster model

NARCIS (Netherlands)

Deng, Y.; Qian, X.; Blöte, H.W.J.

2009-01-01

We formulate a single-cluster Monte Carlo algorithm for the simulation of the random-cluster model. This algorithm is a generalization of the Wolff single-cluster method for the q-state Potts model to noninteger values q>1. Its results for static quantities are in a satisfactory agreement with those

Experiments in physical chemistry

CERN Document Server

Wilson, J M; Denaro, A R

1968-01-01

Experiments in Physical Chemistry, Second Edition provides a compilation of experiments concerning physical chemistry. This book illustrates the link between the theory and practice of physical chemistry. Organized into three parts, this edition begins with an overview of those experiments that generally have a simple theoretical background. Part II contains experiments that are associated with more advanced theory or more developed techniques, or which require a greater degree of experimental skill. Part III consists of experiments that are in the nature of investigations wherein these invest

Mathematics for physical chemistry

CERN Document Server

Mortimer, Robert G

2013-01-01

Mathematics for Physical Chemistry is the ideal supplementary text for practicing chemists and students who want to sharpen their mathematics skills while enrolled in general through physical chemistry courses. This book specifically emphasizes the use of mathematics in the context of physical chemistry, as opposed to being simply a mathematics text. This 4e includes new exercises in each chapter that provide practice in a technique immediately after discussion or example and encourage self-study. The early chapters are constructed around a sequence of mathematical topics, wit

Thermodynamics and proton activities of protic ionic liquids with quantum cluster equilibrium theory

Science.gov (United States)

Ingenmey, Johannes; von Domaros, Michael; Perlt, Eva; Verevkin, Sergey P.; Kirchner, Barbara

2018-05-01

We applied the binary Quantum Cluster Equilibrium (bQCE) method to a number of alkylammonium-based protic ionic liquids in order to predict boiling points, vaporization enthalpies, and proton activities. The theory combines statistical thermodynamics of van-der-Waals-type clusters with ab initio quantum chemistry and yields the partition functions (and associated thermodynamic potentials) of binary mixtures over a wide range of thermodynamic phase points. Unlike conventional cluster approaches that are limited to the prediction of thermodynamic properties, dissociation reactions can be effortlessly included into the bQCE formalism, giving access to ionicities, as well. The method is open to quantum chemical methods at any level of theory, but combination with low-cost composite density functional theory methods and the proposed systematic approach to generate cluster sets provides a computationally inexpensive and mostly parameter-free way to predict such properties at good-to-excellent accuracy. Boiling points can be predicted within an accuracy of 50 K, reaching excellent accuracy for ethylammonium nitrate. Vaporization enthalpies are predicted within an accuracy of 20 kJ mol-1 and can be systematically interpreted on a molecular level. We present the first theoretical approach to predict proton activities in protic ionic liquids, with results fitting well into the experimentally observed correlation. Furthermore, enthalpies of vaporization were measured experimentally for some alkylammonium nitrates and an excellent linear correlation with vaporization enthalpies of their respective parent amines is observed.

clusterMaker: a multi-algorithm clustering plugin for Cytoscape

Directory of Open Access Journals (Sweden)

Morris John H

2011-11-01

Full Text Available Abstract Background In the post-genomic era, the rapid increase in high-throughput data calls for computational tools capable of integrating data of diverse types and facilitating recognition of biologically meaningful patterns within them. For example, protein-protein interaction data sets have been clustered to identify stable complexes, but scientists lack easily accessible tools to facilitate combined analyses of multiple data sets from different types of experiments. Here we present clusterMaker, a Cytoscape plugin that implements several clustering algorithms and provides network, dendrogram, and heat map views of the results. The Cytoscape network is linked to all of the other views, so that a selection in one is immediately reflected in the others. clusterMaker is the first Cytoscape plugin to implement such a wide variety of clustering algorithms and visualizations, including the only implementations of hierarchical clustering, dendrogram plus heat map visualization (tree view, k-means, k-medoid, SCPS, AutoSOME, and native (Java MCL. Results Results are presented in the form of three scenarios of use: analysis of protein expression data using a recently published mouse interactome and a mouse microarray data set of nearly one hundred diverse cell/tissue types; the identification of protein complexes in the yeast Saccharomyces cerevisiae; and the cluster analysis of the vicinal oxygen chelate (VOC enzyme superfamily. For scenario one, we explore functionally enriched mouse interactomes specific to particular cellular phenotypes and apply fuzzy clustering. For scenario two, we explore the prefoldin complex in detail using both physical and genetic interaction clusters. For scenario three, we explore the possible annotation of a protein as a methylmalonyl-CoA epimerase within the VOC superfamily. Cytoscape session files for all three scenarios are provided in the Additional Files section. Conclusions The Cytoscape plugin cluster

Micro-Raman and SEM-EDS analyses to evaluate the nature of salt clusters present in secondary marine aerosol.

Science.gov (United States)

Morillas, Héctor; Marcaida, Iker; García-Florentino, Cristina; Maguregui, Maite; Arana, Gorka; Madariaga, Juan Manuel

2018-02-15

Marine aerosol is a complex inorganic and organic chemistry system which contains several salts, mainly forming different type of salt clusters. Different meteorological parameters have a key role in the formation of these aggregates. The relative humidity (%RH), temperature, CO, SO 2 and NO x levels and even the O 3 levels can promote different chemical reactions giving rise to salt clusters with different morphology and sizes. Sulfates, nitrates and chlorides and even mixed chlorosulfates or nitrosulfates are the final compounds which can be found in environments with a direct influence of marine aerosol. In order to collect and analyze these types of compounds, the use of adequate samplers is crucial. In this work, salt clusters were collected thanks to the use of a self-made passive sampler (SMPS) installed in a 20th century historic building (Punta Begoña Galleries, Getxo, Basque Country, Spain) which is surrounded by a beach and a sportive port. These salt clusters were finally analyzed directly by micro-Raman spectroscopy and Scanning Electron microscopy coupled to Energy Dispersive X-ray spectrometry (SEM-EDS). Copyright © 2017 Elsevier B.V. All rights reserved.

Indoor Chemistry

DEFF Research Database (Denmark)

Weschler, Charles J.; Carslaw, Nicola

2018-01-01

This review aims to encapsulate the importance, ubiquity, and complexity of indoor chemistry. We discuss the many sources of indoor air pollutants and summarize their chemical reactions in the air and on surfaces. We also summarize some of the known impacts of human occupants, who act as sources...... and sinks of indoor chemicals, and whose activities (e.g., cooking, cleaning, smoking) can lead to extremely high pollutant concentrations. As we begin to use increasingly sensitive and selective instrumentation indoors, we are learning more about chemistry in this relatively understudied environment....

Relevant Subspace Clustering

DEFF Research Database (Denmark)

Müller, Emmanuel; Assent, Ira; Günnemann, Stephan

2009-01-01

Subspace clustering aims at detecting clusters in any subspace projection of a high dimensional space. As the number of possible subspace projections is exponential in the number of dimensions, the result is often tremendously large. Recent approaches fail to reduce results to relevant subspace...... clusters. Their results are typically highly redundant, i.e. many clusters are detected multiple times in several projections. In this work, we propose a novel model for relevant subspace clustering (RESCU). We present a global optimization which detects the most interesting non-redundant subspace clusters...... achieves top clustering quality while competing approaches show greatly varying performance....

Chemistry and climate change

International Nuclear Information System (INIS)

Bernier, Jean-Claude; Brasseur, Guy; Brechet, Yves; Candel, Sebastien; Cazenave, Anny; Courtillot, Vincent; Fontecave, Marc; Garnier, Emmanuel; Goebel, Philippe; Legrand, Jack; Legrand, Michel; Le Treut, Herve; Mauberger, Pascal; Dinh-Audouin, Minh-Thu; Olivier, Daniele; Rigny, Paul; Bigot, Bernard

2016-01-01

In its first part, this collective publication addresses the decennial and centuries-old variations of climate: perspectives and implications of climate change for the 21. century, questions remaining about the understanding of climate change from its sources to its modelling, extreme climate variations and societies during the last millennium. The contributions of the second part outline how chemistry is a tool to study climate change: ice chemistry as an archive of our past environment, observations and predictions on sea level rise, relationship between atmosphere chemistry and climate. The third set of contributions discusses the transformation of the energy system for a cleaner atmosphere and the management of the climate risk: the chemical processing of CO_2, actions of chemical companies to support the struggle against climate change, relationship between barrel price and renewable energies, relationship between grid complexity and green energy. The last part outlines the role chemistry can have to be able to do without fossil fuels: chemistry in front of challenges of transformation of the energy system, the use of micro-algae, the use of hydrogen as a vector of energy transition

Horticultural cluster

OpenAIRE

SHERSTIUK S.V.; POSYLAYEVA K.I.

2013-01-01

In the article there are the theoretical and methodological approaches to the nature and existence of the cluster. The cluster differences from other kinds of cooperative and integration associations. Was develop by scientific-practical recommendations for forming a competitive horticultur cluster.

The Chemistry of Population III Supernova Ejecta. II. The Nucleation of Molecular Clusters as a Diagnostic for Dust in the Early Universe

Science.gov (United States)

Cherchneff, Isabelle; Dwek, Eli

2010-04-01

We study the formation of molecular precursors to dust in the ejecta of Population III supernovae (Pop. III SNe) using a chemical kinetic approach to follow the evolution of small dust cluster abundances from day 100 to day 1000 after explosion. Our work focuses on zero-metallicity 20 M sun and 170 M sun progenitors, and we consider fully macroscopically mixed and unmixed ejecta. The dust precursors comprise molecular chains, rings, and small clusters of chemical composition relevant to the initial elemental composition of the ejecta under study. The nucleation stage for small silica, metal oxides and sulfides, pure metal, and carbon clusters is described with a new chemical reaction network highly relevant to the kinetic description of dust formation in hot circumstellar environments. We consider the effect of the pressure dependence of critical nucleation rates and test the impact of microscopically mixed He+ on carbon dust formation. Two cases of metal depletion on silica clusters (full and no depletion) are considered to derive upper limits to the amounts of dust produced in SN ejecta at 1000 days, while the chemical composition of clusters gives a prescription for the type of dust formed in Pop. III SNe. We show that the cluster mass produced in the fully mixed ejecta of a 170 M sun progenitor is ~ 25 M sun whereas its 20 M sun counterpart forms ~ 0.16 M sun of clusters. The unmixed ejecta of a 170 M sun progenitor SN synthesize ~5.6 M sun of small clusters, while its 20 M sun counterpart produces ~0.103 M sun. Our results point to smaller amounts of dust formed in the ejecta of Pop. III SNe by a factor of ~ 5 compared to values derived by previous studies, and to different dust chemical compositions. Such deviations result from some erroneous assumptions made, the inappropriate use of classical nucleation theory to model dust formation, and the omission of the synthesis of molecules in SN ejecta. We also find that the unmixed ejecta of massive Pop. III SNe

Comet Halley and interstellar chemistry

International Nuclear Information System (INIS)

Snyder, L.E.

1989-01-01

How complex is the chemistry of the interstellar medium? How far does it evolve and how has it interacted with the chemistry of the solar system? Are the galactic chemical processes destroyed, preserved, or even enhanced in comets? Are biogenic molecules formed in space and have the formation mechanisms interacted in any way with prebiotic organic chemical processes on the early earth? Radio molecular studies of comets are important for probing deep into the coma and nuclear region and thus may help answer these questions. Comets are believed to be pristine samples of the debris left from the formation of the solar system and may have been the carrier between interstellar and terrestrial prebiotic chemistries. Recent observations of Comet Halley and subsequent comets have given the author an excellent opportunity to study the relationship between interstellar molecular chemistry and cometary chemistry

TreeCluster: Massively scalable transmission clustering using phylogenetic trees

OpenAIRE

Moshiri, Alexander

2018-01-01

Background: The ability to infer transmission clusters from molecular data is critical to designing and evaluating viral control strategies. Viral sequencing datasets are growing rapidly, but standard methods of transmission cluster inference do not scale well beyond thousands of sequences. Results: I present TreeCluster, a cross-platform tool that performs transmission cluster inference on a given phylogenetic tree orders of magnitude faster than existing inference methods and supports multi...

What is the best density functional to describe water clusters: evaluation of widely used density functionals with various basis sets for (H2O)n (n = 1-10)

Czech Academy of Sciences Publication Activity Database

Li, F.; Wang, L.; Zhao, J.; Xie, J. R. H.; Riley, Kevin Eugene; Chen, Z.

2011-01-01

Roč. 130, 2/3 (2011), s. 341-352 ISSN 1432-881X Institutional research plan: CEZ:AV0Z40550506 Keywords : water cluster * density functional theory * MP2 . CCSD(T) * basis set * relative energies Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 2.162, year: 2011

Present address of cutting-edge chemistry in Korea

International Nuclear Information System (INIS)

2007-01-01

This introduces the research center, company and chemistry department with excellent results. This book lists the name of those, which are organic molecule design laboratory by Sunmun university, intelligence Nano technology research center by Biotechnology, Ewha university, Nano chemistry laboratory by Department of chemistry, Yonsei university, science education research center by Haying university, solid chemistry laboratory by Department of Nano science, Ewha university, the center of innovation of chemistry industry with R and D by LG chemistry, Korea Research Institute of Chemical Technology, Department of Chemistry, Sogang university, Department of Chemistry, Busan university and Department of Chemistry, Dankook university.

Voting-based consensus clustering for combining multiple clusterings of chemical structures

Directory of Open Access Journals (Sweden)

Saeed Faisal

2012-12-01

Full Text Available Abstract Background Although many consensus clustering methods have been successfully used for combining multiple classifiers in many areas such as machine learning, applied statistics, pattern recognition and bioinformatics, few consensus clustering methods have been applied for combining multiple clusterings of chemical structures. It is known that any individual clustering method will not always give the best results for all types of applications. So, in this paper, three voting and graph-based consensus clusterings were used for combining multiple clusterings of chemical structures to enhance the ability of separating biologically active molecules from inactive ones in each cluster. Results The cumulative voting-based aggregation algorithm (CVAA, cluster-based similarity partitioning algorithm (CSPA and hyper-graph partitioning algorithm (HGPA were examined. The F-measure and Quality Partition Index method (QPI were used to evaluate the clusterings and the results were compared to the Ward’s clustering method. The MDL Drug Data Report (MDDR dataset was used for experiments and was represented by two 2D fingerprints, ALOGP and ECFP_4. The performance of voting-based consensus clustering method outperformed the Ward’s method using F-measure and QPI method for both ALOGP and ECFP_4 fingerprints, while the graph-based consensus clustering methods outperformed the Ward’s method only for ALOGP using QPI. The Jaccard and Euclidean distance measures were the methods of choice to generate the ensembles, which give the highest values for both criteria. Conclusions The results of the experiments show that consensus clustering methods can improve the effectiveness of chemical structures clusterings. The cumulative voting-based aggregation algorithm (CVAA was the method of choice among consensus clustering methods.

Gas phase ion chemistry

CERN Document Server

Bowers, Michael T

1979-01-01

Gas Phase Ion Chemistry, Volume 1 covers papers on the advances of gas phase ion chemistry. The book discusses the advances in flow tubes and the measurement of ion-molecule rate coefficients and product distributions; the ion chemistry of the earth's atmosphere; and the classical ion-molecule collision theory. The text also describes statistical methods in reaction dynamics; the state selection by photoion-photoelectron coincidence; and the effects of temperature and pressure in the kinetics of ion-molecule reactions. The energy distribution in the unimolecular decomposition of ions, as well

Spatially Resolved Artificial Chemistry

DEFF Research Database (Denmark)

Fellermann, Harold

2009-01-01

Although spatial structures can play a crucial role in chemical systems and can drastically alter the outcome of reactions, the traditional framework of artificial chemistry is a well-stirred tank reactor with no spatial representation in mind. Advanced method development in physical chemistry has...... made a class of models accessible to the realms of artificial chemistry that represent reacting molecules in a coarse-grained fashion in continuous space. This chapter introduces the mathematical models of Brownian dynamics (BD) and dissipative particle dynamics (DPD) for molecular motion and reaction...

Spatially Resolved Artificial Chemistry

DEFF Research Database (Denmark)

Fellermann, Harold

2009-01-01

made a class of models accessible to the realms of artificial chemistry that represent reacting molecules in a coarse-grained fashion in continuous space. This chapter introduces the mathematical models of Brownian dynamics (BD) and dissipative particle dynamics (DPD) for molecular motion and reaction......Although spatial structures can play a crucial role in chemical systems and can drastically alter the outcome of reactions, the traditional framework of artificial chemistry is a well-stirred tank reactor with no spatial representation in mind. Advanced method development in physical chemistry has...

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...

The slow birth of green chemistry

Energy Technology Data Exchange (ETDEWEB)

Amato, I.

1993-03-12

Mainstream chemistry is beginning to look at environmental chemistry as an important solution to environmental problems. This can include research into developing cleaner-burning liquid fuels, cleaning up oil spills, or developing better process methods which engender less pollution, as opposed to previous practices of detecting pollutants without preventing their release to begin with. This article discusses the progress of this chemistry discipline, describes some of the ongoing research, and describes the future for environmental chemistry. An impetus for future growth will be generational change, as young scientists in training are beginning to push faculities into creating programs for environmental chemistry.

OBSERVED SCALING RELATIONS FOR STRONG LENSING CLUSTERS: CONSEQUENCES FOR COSMOLOGY AND CLUSTER ASSEMBLY

International Nuclear Information System (INIS)

Comerford, Julia M.; Moustakas, Leonidas A.; Natarajan, Priyamvada

2010-01-01

Scaling relations of observed galaxy cluster properties are useful tools for constraining cosmological parameters as well as cluster formation histories. One of the key cosmological parameters, σ 8 , is constrained using observed clusters of galaxies, although current estimates of σ 8 from the scaling relations of dynamically relaxed galaxy clusters are limited by the large scatter in the observed cluster mass-temperature (M-T) relation. With a sample of eight strong lensing clusters at 0.3 8 , but combining the cluster concentration-mass relation with the M-T relation enables the inclusion of unrelaxed clusters as well. Thus, the resultant gains in the accuracy of σ 8 measurements from clusters are twofold: the errors on σ 8 are reduced and the cluster sample size is increased. Therefore, the statistics on σ 8 determination from clusters are greatly improved by the inclusion of unrelaxed clusters. Exploring cluster scaling relations further, we find that the correlation between brightest cluster galaxy (BCG) luminosity and cluster mass offers insight into the assembly histories of clusters. We find preliminary evidence for a steeper BCG luminosity-cluster mass relation for strong lensing clusters than the general cluster population, hinting that strong lensing clusters may have had more active merging histories.

Nuclear Chemistry Institute, Mainz University. Annual Report 1995

International Nuclear Information System (INIS)

Denschlag, H.O.

1996-03-01

The annual report of the Institut fuer Kernchemie addresses inter alia three main research activities. The first belongs to the area of basic research, covering studies in the fields of nuclear fission, chemistry of the super-heavy elements and of heavy-ion reactions extending from the Coulomb barrier to relativistic energies, and nuclear astrophysics in connection with the ''r process''. By means of laser technology, high-precision data could be measured of the ionization energies of berkelium and californium. Studies of atomic clusters in the vacuum of an ionization trap revealed interesting aspects. The second major activity was devoted to the analysis of environmental media, applying inter alia neutron activation analysis and resonance ionization mass spectroscopy (RIMS). The third activity resulted in the development of novel processes, or the enhancement of existing processes or methods, for applications in basic research work and in environmental analytics. Another item of interest is the summarizing report on the operation of the TRIGA research reactor. (orig./SR) [de

Cluster Headache

OpenAIRE

Pearce, Iris

1985-01-01

Cluster headache is the most severe primary headache with recurrent pain attacks described as worse than giving birth. The aim of this paper was to make an overview of current knowledge on cluster headache with a focus on pathophysiology and treatment. This paper presents hypotheses of cluster headache pathophysiology, current treatment options and possible future therapy approaches. For years, the hypothalamus was regarded as the key structure in cluster headache, but is now thought to be pa...

HMI scientific report - chemistry 1987

International Nuclear Information System (INIS)

1989-01-01

Results of the R and D activities of the Radiation Chemistry Department, Hahn-Meitner-Institut, are reported, primarily dealing with the following subjects: Interface processes and energy conversion, high-energy photochemistry and radiation chemistry as well as trace elements chemistry. A list of publications and lectures is added and gives a view on results obtained in research and development. (EF) [de

Research for the advancement of green chemistry practice: Studies in atmospheric and educational chemistry

Science.gov (United States)

Cullipher, Steven Gene

Green chemistry is a philosophy of chemistry that emphasizes a decreasing dependence on limited non-renewable resources and an increasing focus on preventing pollution byproducts of the chemical industry. In short, it is the discipline of chemistry practiced through the lens of environmental stewardship. In an effort to advance the practice of green chemistry, three studies will be described that have ramifications for the practice. The first study examines the atmospheric oxidation of a hydrofluorinated ether, a third-generation CFC replacement compound with primarily unknown atmospheric degradation products. Determination of these products has the potential to impact decisions on refrigerant usage in the future. The second study examines chemistry students' development of understanding benefits-costs-risks analysis when presented with two real-world scenarios: refrigerant choice and fuel choice. By studying how benefits-costs-risks thinking develops, curricular materials and instructional approaches can be designed to better foster the development of an ability that is both necessary for green chemists and important in daily decision-making for non-chemists. The final study uses eye tracking technology to examine students' abilities to interpret molecular properties from structural information in the context of global warming. Such abilities are fundamental if chemists are to appropriately assess risks and hazards of chemistry practice.

The Breath of Chemistry

DEFF Research Database (Denmark)

Josephsen, Jens

The present preliminary text is a short thematic presentation in biological inorganic chemistry meant to illustrate general and inorganic (especially coordination) chemistry in biochemistry. The emphasis is on molecular models to explain features of the complicated mechanisms essential to breathing...

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.

Does a Course on the History and Philosophy of Chemistry Have Any Effect on Prospective Chemistry Teachers' Perceptions? The Case of Chemistry and the Chemist

Science.gov (United States)

Sendur, G.; Polat, M.; Kazanci, C.

2017-01-01

The creative comparisons prospective chemistry teachers make about "chemistry" and the "chemist" may reflect how they perceive these concepts. In this sense, it seems important to determine which creative comparisons prospective teachers make with respect to these and how these can change after the history of chemistry is…

Green chemistry

International Nuclear Information System (INIS)

Warner, John C.; Cannon, Amy S.; Dye, Kevin M.

2004-01-01

A grand challenge facing government, industry, and academia in the relationship of our technological society to the environment is reinventing the use of materials. To address this challenge, collaboration from an interdisciplinary group of stakeholders will be necessary. Traditionally, the approach to risk management of materials and chemicals has been through inerventions intended to reduce exposure to materials that are hazardous to health and the environment. In 1990, the Pollution Prevention Act encouraged a new tact-elimination of hazards at the source. An emerging approach to this grand challenge seeks to embed the diverse set of environmental perspectives and interests in the everyday practice of the people most responsible for using and creating new materials--chemists. The approach, which has come to be known as Green Chemistry, intends to eliminate intrinsic hazard itself, rather than focusing on reducing risk by minimizing exposure. This chapter addresses the representation of downstream environmental stakeholder interests in the upstream everyday practice that is reinventing chemistry and its material inputs, products, and waste as described in the '12 Principles of Green Chemistry'

11th National Meeting of Organic Chemistry and 4th Meeting of Therapeutic Chemistry

Science.gov (United States)

Sousa, Maria Emília; Araújo, Maria João; do Vale, Maria Luísa; Andrade, Paula B.; Branco, Paula; Gomes, Paula; Moreira, Rui; Pinho e Melo, Teresa M.V.D.; Freitas, Victor

2016-01-01

For the first time under the auspices of Sociedade Portuguesa de Química, the competences of two important fields of Chemistry are brought together into a single event, the 11st National Organic Chemistry Meeting and the the 4th National Medicinal Chemistry Meeting, to highlight complementarities and to promote new synergies. Abstracts of plenary lectures, oral communications, and posters presented during the meeting are collected in this report. PMID:27102166

11th National Meeting of Organic Chemistry and 4th Meeting of Therapeutic Chemistry

Directory of Open Access Journals (Sweden)

Maria Emília Sousa

2016-03-01

Full Text Available For the first time under the auspices of Sociedade Portuguesa de Química, the competences of two important fields of Chemistry are brought together into a single event, the 11st National Organic Chemistry Meeting and the the 4th National Medicinal Chemistry Meeting, to highlight complementarities and to promote new synergies. Abstracts of plenary lectures, oral communications, and posters presented during the meeting are collected in this report.

Properties of an ionised-cluster beam from a vaporised-cluster ion source

International Nuclear Information System (INIS)