Probing chemical homogeneity within single cluster impact sites

2010 ◽  
Vol 43 (1-2) ◽  
pp. 551-554 ◽  
Author(s):  
Veronica Pinnick ◽  
Stanislav V. Verkhoturov ◽  
Leonid Kaledin ◽  
Emile A. Schweikert
Keyword(s):  
Chemical Homogeneity ◽  
Single Cluster

scholarly journals Fe3 Cluster Anchored on the C2N Monolayer for Efficient Electrochemical Nitrogen Fixation

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 974
Author(s):  
Bing Han ◽  
Haihong Meng ◽  
Fengyu Li ◽  
Jingxiang Zhao
Keyword(s):  
Nitrogen Fixation ◽  
First Principles ◽  
Catalytic Performance ◽  
Reduction Reaction ◽  
First Principles Calculations ◽  
Ammonia Gas ◽  
Nitrogen Reduction ◽  
Single Cluster ◽  
Excellent Catalytic Performance ◽  
Production Of Ammonia

Under the current double challenge of energy and the environment, an effective nitrogen reduction reaction (NRR) has become a very urgent need. However, the largest production of ammonia gas today is carried out by the Haber–Bosch process, which has many disadvantages, among which energy consumption and air pollution are typical. As the best alternative procedure, electrochemistry has received extensive attention. In this paper, a catalyst loaded with Fe3 clusters on the two-dimensional material C2N (Fe3@C2N) is proposed to achieve effective electrochemical NRR, and our first-principles calculations reveal that the stable Fe3@C2N exhibits excellent catalytic performance for electrochemical nitrogen fixation with a limiting potential of 0.57 eV, while also suppressing the major competing hydrogen evolution reaction. Our findings will open a new door for the development of non-precious single-cluster catalysts for effective nitrogen reduction reactions.

scholarly journals Genetic Relatedness of the Streptococcus pneumoniae Capsular Biosynthetic Loci

2007 ◽  
Vol 189 (21) ◽  
pp. 7841-7855 ◽  
Author(s):  
Angeliki Mavroidi ◽  
David M. Aanensen ◽  
Daniel Godoy ◽  
Ian C. Skovsted ◽  
Margit S. Kaltoft ◽  
...  
Keyword(s):  
Streptococcus Pneumoniae ◽  
Genetic Relatedness ◽  
Pneumococcal Serotypes ◽  
Major Cluster ◽  
Genes Encoding ◽  
Pneumococcal Serotype ◽  
Streptococcal Polysaccharide ◽  
Single Cluster ◽  
Dependent Pathway ◽  
Sequence Similarities

ABSTRACT Streptococcus pneumoniae (the pneumococcus) produces 1 of 91 capsular polysaccharides (CPS) that define the serotype. The cps loci of 88 pneumococcal serotypes whose CPS is synthesized by the Wzy-dependent pathway were compared with each other and with additional streptococcal polysaccharide biosynthetic loci and were clustered according to the proportion of shared homology groups (HGs), weighted for the sequence similarities between the genes encoding the shared HGs. The cps loci of the 88 pneumococcal serotypes were distributed into eight major clusters and 21 subclusters. All serotypes within the same serogroup fell into the same major cluster, but in six cases, serotypes within the same serogroup were in different subclusters and, conversely, nine subclusters included completely different serotypes. The closely related cps loci within a subcluster were compared to the known CPS structures to relate gene content to structure. The Streptococcus oralis and Streptococcus mitis polysaccharide biosynthetic loci clustered within the pneumococcal cps loci and were in a subcluster that also included the cps locus of pneumococcal serotype 21, whereas the Streptococcus agalactiae cps loci formed a single cluster that was not closely related to any of the pneumococcal cps clusters.

scholarly journals Parallelization of the Wolff single-cluster algorithm

2010 ◽  
Vol 81 (2) ◽  
Author(s):  
J. Kaupužs ◽  
J. Rimšāns ◽  
R. V. N. Melnik
Keyword(s):  
Cluster Algorithm ◽  
Single Cluster

Influence of Stress and Chemical Homogeneity on Dielectric Properties of BaTi0.9Zr0.1O3

2004 ◽  
Vol 83 (10) ◽  
pp. 2610-2612
Author(s):  
Sven Gijp ◽  
Johan E. Elshof ◽  
Oliver Steigelmann ◽  
Henk Verweij
Keyword(s):  
Dielectric Properties ◽  
Chemical Homogeneity

Sequence of the Tribolium castaneum Homeotic Complex: The Region Corresponding to the Drosophila melanogaster Antennapedia Complex

Genetics ◽  
2002 ◽  
Vol 160 (3) ◽  
pp. 1067-1074
Author(s):  
Susan J Brown ◽  
John P Fellers ◽  
Teresa D Shippy ◽  
Elizabeth A Richardson ◽  
Mark Maxwell ◽  
...  
Keyword(s):  
Tribolium Castaneum ◽  
Hox Genes ◽  
Transcription Unit ◽  
Sex Combs Reduced ◽  
Sex Combs ◽  
Selector Genes ◽  
Homeotic Selector Genes ◽  
Encoding Genes ◽  
Single Cluster ◽  
Homeotic Selector

Abstract The homeotic selector genes of the red flour beetle, Tribolium castaneum, are located in a single cluster. We have sequenced the region containing the homeotic selector genes required for proper development of the head and anterior thorax, which is the counterpart of the ANTC in Drosophila. This 280-kb interval contains eight homeodomain-encoding genes, including single orthologs of the Drosophila genes labial, proboscipedia, Deformed, Sex combs reduced, fushi tarazu, and Antennapedia, as well as two orthologs of zerknüllt. These genes are all oriented in the same direction, as are the Hox genes of amphioxus, mice, and humans. Although each transcription unit is similar to its Drosophila counterpart in size, the Tribolium genes contain fewer introns (with the exception of the two zerknüllt genes), produce shorter mRNAs, and encode smaller proteins. Unlike the ANTC, this region of the Tribolium HOMC contains no additional genes.

A POLYSACCHARIDE FROM THE BLUE-GREEN ALGA, ANABAENA CYLINDRICA

1954 ◽  
Vol 32 (11) ◽  
pp. 999-1004 ◽  
Author(s):  
C. T. Bishop ◽  
G. A. Adams ◽  
E. O. Hughes
Keyword(s):  
Acid Hydrolysis ◽  
Fresh Water ◽  
Green Alga ◽  
Culture Medium ◽  
Glucuronic Acid ◽  
Molar Ratio ◽  
Blue Green Alga ◽  
Anabaena Cylindrica ◽  
Chemical Homogeneity ◽  
Fresh Water Alga

A complex polysaccharide has been isolated from the fresh-water alga, Anabaena cylindrica, grown in a synthetic culture medium. Prolonged acid hydrolysis yielded glucose, xylose, glucuronic acid, galactose, rhamnose, and arabinose in a molar ratio of 5: 4: 4: 1: 1: 1. Chemical fractionations of the polysaccharide material from solution in cupriethylenediamine, and of its acetate from organic solvents indicated chemical homogeneity.

scholarly journals Impact of Surface Chemistry of Silicon Nanoparticles on the Structural and Electrochemical Properties of Si/Ni3.4Sn4 Composite Anode for Li-Ion Batteries

Nanomaterials ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 18
Author(s):  
Tahar Azib ◽  
Claire Thaury ◽  
Fermin Cuevas ◽  
Eric Leroy ◽  
Christian Jordy ◽  
...  
Keyword(s):  
Surface Chemistry ◽  
Electrochemical Properties ◽  
Large Scale ◽  
Silicon Nanoparticles ◽  
Lithium Ion ◽  
Li Ion Batteries ◽  
Chemical Homogeneity ◽  
Electrochemical Behaviors ◽  
Pure Silicon ◽  
Li Ion

Embedding silicon nanoparticles in an intermetallic matrix is a promising strategy to produce remarkable bulk anode materials for lithium-ion (Li-ion) batteries with low potential, high electrochemical capacity and good cycling stability. These composite materials can be synthetized at a large scale using mechanical milling. However, for Si-Ni3Sn4 composites, milling also induces a chemical reaction between the two components leading to the formation of free Sn and NiSi2, which is detrimental to the performance of the electrode. To prevent this reaction, a modification of the surface chemistry of the silicon has been undertaken. Si nanoparticles coated with a surface layer of either carbon or oxide were used instead of pure silicon. The influence of the coating on the composition, (micro)structure and electrochemical properties of Si-Ni3Sn4 composites is studied and compared with that of pure Si. Si coating strongly reduces the reaction between Si and Ni3Sn4 during milling. Moreover, contrary to pure silicon, Si-coated composites have a plate-like morphology in which the surface-modified silicon particles are surrounded by a nanostructured, Ni3Sn4-based matrix leading to smooth potential profiles during electrochemical cycling. The chemical homogeneity of the matrix is more uniform for carbon-coated than for oxygen-coated silicon. As a consequence, different electrochemical behaviors are obtained depending on the surface chemistry, with better lithiation properties for the carbon-covered silicon able to deliver over 500 mAh/g for at least 400 cycles.

Phase Transition of As-Milled and Annealed CrCuFeMnNi High-Entropy Alloy Powder

NANO ◽  
2018 ◽  
Vol 13 (09) ◽  
pp. 1850100 ◽  
Author(s):  
Rui-Feng Zhao ◽  
Bo Ren ◽  
Guo-Peng Zhang ◽  
Zhong-Xia Liu ◽  
Jian-Jian Zhang
Keyword(s):  
Phase Transition ◽  
Solution Structure ◽  
Milling Time ◽  
Structure Evolution ◽  
High Entropy Alloy ◽  
Chemical Homogeneity ◽  
High Entropy ◽  
Dynamic Phase Transition ◽  
Fcc Phase ◽  
Bcc Phase

The CrCuFeMnNi high entropy alloy (HEA) powder was synthesized by mechanical alloying. The effects of milling time and subsequent annealing on the structure evolution, thermostability and magnetic property were investigated. After 50[Formula: see text]h of milling, the CrCuFeMnNi HEA powder consisted of a major FCC phase and a small amount of BCC phase. The crystallite size and strain lattice of 50[Formula: see text]h-ball-milled CrCuFeMnNi HEA powder were 12[Formula: see text]nm and 1.02%, respectively. The powder exhibited refined morphology and excellent chemical homogeneity. The supersaturated solid solution structure of the as-milled HEA powder transformed into FCC1, FCC2, a small amount of BCC and [Formula: see text] phase in annealed state. Most of the BCC phase decomposed into FCC (mainly FCC2 phase) and [Formula: see text] phases, and the dynamic phase transition was almost in equilibrium at 900[Formula: see text]C. The saturated magnetization and coercivity force of the 50[Formula: see text]h-ball-milled CrCuFeMnNi HEA powder were respectively 16.1[Formula: see text]emu/g and 56.2[Formula: see text]Oe.

scholarly journals A proposed procedure for the analysis of large phytosociological data sets in the classification of South African grasslands

Koedoe ◽  
1995 ◽  
Vol 38 (1) ◽  
Author(s):  
G.J. Bredenkamp ◽  
H. Bezuidenhout
Keyword(s):  
South African ◽  
Plant Communities ◽  
Vegetation Type ◽  
Second Step ◽  
Data Sets ◽  
Vegetation Types ◽  
Related Plant ◽  
Single Cluster ◽  
Synoptic Table

A procedure for the effective classification of large phytosociological data sets, and the combination of many data sets from various parts of the South African grasslands is demonstrated. The procedure suggests a region by region or project by project treatment of the data. The analyses are performed step by step to effectively bring together all releves of similar or related plant communities. The first step involves a separate numerical classification of each subset (region), and subsequent refinement by Braun- Blanquet procedures. The resulting plant communities are summarised in a single synoptic table, by calculating a synoptic value for each species in each community. In the second step all communities in the synoptic table are classified by numerical analysis, to bring related communities from different regions or studies together in a single cluster. After refinement of these clusters by Braun-Blanquet procedures, broad vegetation types are identified. As a third step phytosociological tables are compiled for each iden- tified broad vegetation type, and a comprehensive abstract hierarchy constructed.

Event Mining Through Clustering

2014 ◽  
Vol 23 (1) ◽  
pp. 59-73
Author(s):  
E. Umamaheswari ◽  
T.V. Geetha
Keyword(s):  
Clustering Algorithm ◽  
Semantic Representation ◽  
Clustering Algorithms ◽  
Event Semantics ◽  
Information Retrieval Evaluation ◽  
Event Mining ◽  
Unique Word ◽  
Event Clustering ◽  
Cluster Efficiency ◽  
Single Cluster

AbstractTraditional document clustering algorithms consider text-based features such as unique word count, concept count, etc. to cluster documents. Meanwhile, event mining is the extraction of specific events, their related sub-events, and the associated semantic relations from documents. This work discusses an approach to event mining through clustering. The Universal Networking Language (UNL)-based subgraph, a semantic representation of the document, is used as the input for clustering. Our research focuses on exploring the use of three different feature sets for event clustering and comparing the approaches used for specific event mining. In our previous work, the clustering algorithm used UNL-based event semantics to represent event context for clustering. However, this approach resulted in different events with similar semantics being clustered together. Hence, instead of considering only UNL event semantics, we considered assigning additional weights to similarity between event contexts with event-related attributes such as time, place, and persons. Although we get specific events in a single cluster, sub-events related to the specific events are not necessarily in a single cluster. Therefore, to improve our cluster efficiency, connective terms between two sentences and their representation as UNL subgraphs were also considered for similarity determination. By combining UNL semantics, event-specific arguments similarity, and connective term concepts between sentences, we were able to obtain clusters for specific events and their sub-events. We have used 112 000 Tamil documents from the Forum for Information Retrieval Evaluation data corpus and achieved good results. We have also compared our approach with the previous state-of-the-art approach for Router-RCV1 corpus and achieved 30% improvements in precision.

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