Role of Cluster Size in Catalysis:  Spectroscopic Investigation of γ-Al2O3-Supported Ir4and Ir6during Ethene Hydrogenation

2003 ◽  
Vol 125 (23) ◽  
pp. 7107-7115 ◽  
Author(s):  
Andrew M. Argo ◽  
Josip F. Odzak ◽  
Bruce C. Gates
Keyword(s):  
Spectroscopic Investigation ◽  
Cluster Size ◽  
Ethene Hydrogenation

Spectroscopic Investigation of Heterogeneous Ziegler-Natta Catalysts: Ti and Mg Chloride Tetrahydrofuranates, Their Interaction Compound, and the Role of the Activator

2011 ◽  
Vol 17 (31) ◽  
pp. 8648-8656 ◽  
Author(s):  
Kalaivani Seenivasan ◽  
Anna Sommazzi ◽  
Francesca Bonino ◽  
Silvia Bordiga ◽  
Elena Groppo
Keyword(s):  
Spectroscopic Investigation ◽  
Ziegler Natta Catalysts

Gd–Sc-Based Mixed-Metal Nitride Cluster Fullerenes: Mutual Influence of the Cage and Cluster Size and the Role of Scandium in the Electronic Structure

2013 ◽  
Vol 52 (6) ◽  
pp. 3368-3380 ◽  
Author(s):  
Anna L. Svitova ◽  
Alexey A. Popov ◽  
Lothar Dunsch
Keyword(s):  
Electronic Structure ◽  
Cluster Size ◽  
Mutual Influence ◽  
Metal Nitride ◽  
Mixed Metal

Failure analysis of sandwich-type ceramic-on-ceramic hip joints: A spectroscopic investigation into the role of the polyethylene shell component

2014 ◽  
Vol 31 ◽  
pp. 55-67 ◽  
Author(s):  
Shinya Okita ◽  
Masahiro Hasegawa ◽  
Yasuhito Takahashi ◽  
Leonardo Puppulin ◽  
Akihiro Sudo ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Spectroscopic Investigation ◽  
Hip Joints ◽  
Sandwich Type ◽  
Ceramic On Ceramic

Aspects of the Shi–Seinfeld–Okuyama theory of transient nucleation

1995 ◽  
Vol 10 (7) ◽  
pp. 1674-1679 ◽  
Author(s):  
G. Sundar ◽  
J.J. Hoyt
Keyword(s):  
High Temperature ◽  
Singular Perturbation ◽  
Incubation Time ◽  
Cluster Size ◽  
Analytic Solution ◽  
Time Dependent ◽  
Transient Kinetics ◽  
High Temperature Anneal ◽  
Transient Nucleation

The analytic solution to the time-dependent nucleation problem by Shi-Seinfeld-Okuyama (SSO) [Phys. Rev. A 41, 2101 (1990)] is reviewed. The singular perturbation solution employed by SSO is extended to examine the effect of initial quench position on the incubation time. Two cases are discussed. The first investigates the role of excess vacancies from the high temperature quench on the transient kinetics. The second case examines the change in the incubation time due to the effects of a preexisting subcritical cluster size distribution which forms during the high temperature anneal.

scholarly journals COVID-19 clusters in schools: frequency, size, and transmission rates from crowdsourced exposure reports

2021 ◽  
Author(s):  
Paul Tupper ◽  
Shraddha Pai ◽  
Caroline Colijn ◽  
Keyword(s):  
Cluster Size ◽  
Index Case ◽  
Transmission Rate ◽  
Parameter Estimates ◽  
Variable Rate ◽  
Transmission Rates ◽  
The Us ◽  
Variable Transmission ◽  
Index Cases

The role of schools in the spread of the COVID-19 pandemic is controversial, with some claiming they are an important driver of the pandemic and others arguing that transmission in schools is negligible. School cluster reports that have been collected in various jurisdictions are a source of data about transmission in schools. These reports consist of the name of a school, a date, and the number of students known to be infected. We provide a simple model for the frequency and size of clusters in this data, based on random arrivals of index cases at schools who then infect their classmates with a highly variable rate, fitting the overdispersion evident in the data. We fit our model to reports for several jurisdictions in the US and Canada, providing estimates of mean and dispersion for cluster size, whilst factoring in imperfect ascertainment. Our parameter estimates are robust to variations in ascertainment fraction. We use these estimates in three ways: i) to explore how uneven the distribution of cases is among different clusters in different jurisdictions (that is, what fraction of cases are in the 20% largest clusters), ii) to estimate how long it will be until we see a cluster a given size in jurisdiction, and iii) to determine the distribution of instantaneous transmission rate β among different index case. We show how these latter distribution can be used in simulations of school transmission where we explore the effect of different interventions, in the context of highly variable transmission rates.

Role of Nanostructures in Anomalous Thermal Conductivity of Nanofluids

2014 ◽  
Author(s):  
S. M. Sohel Murshed ◽  
C. A. Nieto de Castro
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Properties ◽  
Cluster Size ◽  
Molecular Level ◽  
Positive Impact ◽  
Potential Applications ◽  
Individual Nanoparticles ◽  
Transfer Mechanisms

Nanofluids have stimulated immense research interest due to their superior thermophysical properties, heat transfer features and potential applications in numerous important fields. Role of nanostructures in heat transfer mechanisms and thermal properties particularly thermal conductivity of nanofluids has been presented and relevant studies are critically reviewed in this study. Research demonstrated that nanofluids exhibit anomalous thermal conductivity (generally higher than their base fluids) which increases with the loading of nanoparticles. Despite of some findings on positive impact of agglomeration or clustering of nanoparticles on thermal conductivity, contrary findings (negative) and argumentations are still widely accepted in the nanofluids research community. Literature results showed that while cluster size increases with concentration of nanoparticles, thermal conductivity of nanofluids decreases with increasing the cluster size. However, it is not yet well-understood how to control the morphology of the clusters of nanoparticles and how do they play role in changing the thermal properties of nanofluids. Furthermore, studies revealed that the primary shape or structures of nanomaterials also influence the properties of nanofluids. Nanofluids containing nanotubes of large aspect ratio exhibit superior thermal conductivity compared to nanofluids having nanoparticles of any other shapes. Nanorods (cylinder)-laden nanofluids showed slightly higher thermal conductivity than that of nanosphere-based nanofluids. Nevertheless, the structures of agglomerated or individual nanoparticles and their nano- or molecular-level activities in the host fluids are mainly responsible for the anomalous thermal conductivity of nanofluids.

Ethene hydrogenation over silica-supported Ru and Ru-Cu bimetallic catalysts: the role of defects and special sites

1992 ◽  
Vol 12 (2-3) ◽  
pp. 165-175 ◽  
Author(s):  
S. Bhatia ◽  
X. Wu ◽  
D.K. Sanders ◽  
B.C. Gerstein ◽  
M. Pruski ◽  
...  
Keyword(s):  
Bimetallic Catalysts ◽  
Ethene Hydrogenation

scholarly journals The Role of Cluster Size and Protein Spatial Pattern in the Immunological Synapse

2009 ◽  
Vol 96 (3) ◽  
pp. 283a
Author(s):  
Niña C. Hartman ◽  
Wan-Chen Lin ◽  
Cheng-han Yu ◽  
Jay T. Groves
Keyword(s):  
Spatial Pattern ◽  
Cluster Size ◽  
Immunological Synapse
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