N2O decomposition over (μ-oxo)(μ-hydroxo)di-iron complex supported by ZSM-5 zeolite: effect of cluster size on DFT energy profile

1983 ◽

Vol 41 ◽

pp. 338-339

Author(s):

M. A. Listvan ◽

R. P. Andres

Keyword(s):

Cluster Size ◽

Metal Clusters ◽

Experimental Parameter ◽

Carbon Films ◽

Metal Species ◽

Silver Clusters ◽

Free Jet ◽

Size Dependent ◽

Cluster Properties ◽

Controllable Size

Knowledge of the function and structure of small metal clusters is one goal of research in catalysis. One important experimental parameter is cluster size. Ideally, one would like to produce metal clusters of regulated size in order to characterize size-dependent cluster properties.A source has been developed which is capable of producing microscopic metal clusters of controllable size (in the range 5-500 atoms) This source, the Multiple Expansion Cluster Source, with a Free Jet Deceleration Filter (MECS/FJDF) operates as follows. The bulk metal is heated in an oven to give controlled concentrations of monomer and dimer which were expanded sonically. These metal species were quenched and condensed in He and filtered to produce areosol particles of a controlled size as verified by mass spectrometer measurements. The clusters were caught on pre-mounted, clean carbon films. The grids were then transferred in air for microscopic examination. MECS/FJDF was used to produce two different sizes of silver clusters for this study: nominally Ag6 and Ag50.

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Cluster size effects revisited

Journal de Chimie Physique ◽

10.1051/jcp/1995920205 ◽

1995 ◽

Vol 92 ◽

pp. 205-225 ◽

Cited By ~ 21

Author(s):

J Jortner

Keyword(s):

Size Effects ◽

Cluster Size

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The Role of the Interaction between Fe(III) and Cell Surface in the Accumulation of 67Ga by Tumor Cells

Nuklearmedizin ◽

10.1055/s-0038-1629590 ◽

1991 ◽

Vol 30 (06) ◽

pp. 290-293 ◽

Cited By ~ 1

Author(s):

P. Maleki ◽

A. Martinezi ◽

M. C. Crone-Escanye ◽

J. Robert ◽

L. J. Anghileri

Keyword(s):

Cell Surface ◽

Tumor Cells ◽

Ionic Composition ◽

Iron Complex ◽

Iron Binding ◽

Complex Time ◽

Interaction Product ◽

Thermodynamic Constant ◽

Number Of Cells

The study of the interaction between complexed iron and tumor cells in the presence of 67Ga-citrate indicates that a phenomenon of iron-binding related to the thermodynamic constant of stability of the iron complex, and a hydrolysis (or anion penetration) of the interaction product determine the uptake of 67Ga. The effects of various parameters such as ionic composition of the medium, nature of the iron complex, time of incubation and number of cells are discussed.

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MOLECULAR AND CRYSTAL STRUCTURE OF A CATIONIC DINITROSYL IRON COMPLEX WITH 1,3-DIMETHYLTHIOUREA

Журнал структурной химии ◽

10.15372/jsc20170217 ◽

2017 ◽

Keyword(s):

Crystal Structure ◽

Iron Complex ◽

Molecular And Crystal Structure ◽

Dinitrosyl Iron Complex ◽

Dinitrosyl Iron

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Design a Cellular System with Different Cluster Size and Investigate the Co Channel Interference Assuming a Limited Geographical Area with Fixed Channel Assignment Strategy

International Journal of Science and Engineering Invention ◽

10.23958/ijsei/vol03-i04/02 ◽

2017 ◽

Vol 3 (04) ◽

Author(s):

Md.Taz Uddin, Ahmed al Marzean, Md Rafiqul Islam, Shahjahan Ahmed

Keyword(s):

Channel Assignment ◽

Cluster Size ◽

Geographical Area ◽

Cellular System ◽

Communication Industry ◽

Mobile Operator ◽

Channel Interference ◽

Assignment Strategy ◽

Fixed Channel Assignment ◽

Mobile Communication Industry

There are different communication standards in present mobile communication industry. Each of this standards has its own feature, architecture, and channel assignment strategies. Each mobile operator uses one of any standard and their aim is to support as much user as possible to communicate with tolerable interference. For that reason they use different cluster size and frequency planning to cover entire geographical area. To reuse the given bandwidth within the entire geographical area some cells uses same sets of frequency and interference arise when the distance between these cells is small. Also when distance is large then capacity is going low. In this thesis our work is to investigation the co channel interference among different cluster size assuming a limited sub urban geographical area in a cellular GSM network. Also we calculate the number of users using each of this cluster size and finally design a cellular system in this geographical area using best results (minimum interference and maximum capacity).

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Mechanisms of ATP to cAMP Conversion Catalyzed by the Mammalian Adenylyl Cyclase: A Role of Magnesium Coordination Shells and Proton Wires

10.26434/chemrxiv.9209180 ◽

2019 ◽

Author(s):

Bella Grigorenko ◽

Igor Polyakov ◽

Alexander Nemukhin

Keyword(s):

Adenylyl Cyclase ◽

Bond Cleavage ◽

Cyclic Adenosine Monophosphate ◽

Adenosine Monophosphate ◽

Md Simulations ◽

Coordination Shell ◽

Energy Profile ◽

One Step ◽

Type V

We report a mechanism of adenosine triphosphate (ATP) to cyclic adenosine monophosphate (cAMP) conversion by the mammalian type V adenylyl cyclase revealed in molecular dynamics (MD) and quantum mechanics/molecular mechanics (QM/MM) simulations. We characterize a set of computationally derived enzyme-substrate (ES) structures showing an important role of coordination shells of magnesium ions in the solvent accessible active site. Several stable six-fold coordination shells of MgA2+ are observed in MD simulations of ES complexes. In the lowest energy ES conformation, the coordination shell of MgA2+ does not include the Oδ1 atom of the conserved Asp440 residue. Starting from this conformation, a one-step reaction mechanism is characterized which includes proton transfer from the ribose O3'H3' group in ATP to Asp440 via a shuttling water molecule and PA-O3A bond cleavage and O3'-PA bond formation. The energy profile of this route is consistent with the observed reaction kinetics. In a higher energy ES conformation, MgA2+ is bound to the Oδ1(Asp440) atom as suggested in the relevant crystal structure of the protein with a substrate analog. The computed energy profile initiated by this ES is characterized by higher energy expenses to complete the reaction. Consistently with experimental data, we show that the Asp440Ala mutant of the enzyme should exhibit a reduced but retained activity. All considered reaction pathways include proton wires from the O3'H3' group via shuttling water molecules.

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Survey for Transition of Normal Reaction

International Journal of Recent Advances in Science and Technology ◽

10.30750/ijarst.536 ◽

2018 ◽

Vol 5 (3) ◽

Author(s):

Hassan Akbari Rahimi

Keyword(s):

Transition State ◽

Reactive Intermediates ◽

The State ◽

Energy Profile ◽

Normal Reaction ◽

Unstable Molecules ◽

The Difference ◽

Bond Vibration ◽

Unstable Molecule ◽

Profile Diagram

Transition of reaction is a short-lived unstable molecule in a reaction which is formed in between the reaction when reactants change into products. Whereas, transition state is just the state before formation of new molecule (involves breaking of bonds of reactants and formation of new ones) Transition of reaction differs from a transition state in that the intermediate has a discrete lifetime (be it a few nanoseconds or many days), whereas a transition state lasts for just one bond vibration cycle. Intermediates may be unstable molecules (in which case they are called reactive intermediates) or highly stable molecules. The difference between them can be better described through the energy profile diagram.

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