Synthesis of a New Class of Compounds Containing a Ln−O−Al Arrangement and Their Reactions and Catalytic Properties

2005 ◽  
Vol 127 (20) ◽  
pp. 7521-7528 ◽  
Author(s):  
Jianfang Chai ◽  
Vojtech Jancik ◽  
Sanjay Singh ◽  
Hongping Zhu ◽  
Cheng He ◽  
...  
Keyword(s):  
Catalytic Properties ◽  
New Class

Thiolate-protected Au38(SR)24 nanocluster: size-focusing synthesis, structure determination, intrinsic chirality, and beyond

2014 ◽  
Vol 86 (1) ◽  
pp. 27-37 ◽  
Author(s):  
Huifeng Qian
Keyword(s):  
Electronic Structure ◽  
Structure Determination ◽  
Electronic Transition ◽  
Catalytic Properties ◽  
Au Nanoclusters ◽  
Chiroptical Properties ◽  
New Class ◽  
Biological Labeling ◽  
Homo Lumo

Abstract Thiolate-protected Au nanoclusters with core diameters smaller than 2 nm have captured considerable attention in recent years due to their diverse applications ranging from biological labeling to photovoltaics and catalysis. This new class of nanomaterials exhibits discrete electronic structure and molecular-like properties, such as HOMO-LUMO electronic transition, intrinsic magnetism, chiroptical properties, and enhanced catalytic properties. This review focuses on the research into thiolate-protected Au38(SR)24 – one of the most representative nanoclusters, including its identification, size-focusing synthesis, structure determination, and intrinsic chirality. The properties of two size-adjacent Au nanoclusters [Au40(SR)24 and Au36(SR)24] are also discussed. The experimental and theoretical methodologies developed in studies of the Au38(SR)24 model nanocluster open up new opportunities in the synthesis and properties investigation of other atomically precise Aun(SR)m nanoclusters.

scholarly journals Polymeric carbon nitrides and related metal-free materials for energy and environmental applications

2020 ◽  
Vol 8 (22) ◽  
pp. 11075-11116 ◽  
Author(s):  
Jesús Barrio ◽  
Michael Volokh ◽  
Menny Shalom
Keyword(s):  
Catalytic Properties ◽  
Functional Materials ◽  
Environmental Applications ◽  
Facile Synthesis ◽  
Metal Free ◽  
New Class ◽  
Wide Range ◽  
Carbon Nitrides ◽  
Polymeric Carbon

Carbon nitrides have emerged as a new class of functional materials for a wide range of energy and environmental applications due to their chemical, photophysical and catalytic properties as well as their low-price, facile synthesis and stability.

Catalytic Properties of the SHS Products - Review

2010 ◽  
Vol 63 ◽  
pp. 287-296 ◽  
Author(s):  
Galina Xanthopoulou
Keyword(s):  
Catalytic Properties ◽  
Mechanical Tests ◽  
Exothermic Reactions ◽  
New Class ◽  
Processing Times ◽  
High Temperature Synthesis ◽  
Physico Chemical ◽  
Fast Processing ◽  
Catalytically Active ◽  
Reduction Of Nox

The Self-Propagating High-Temperature Synthesis (SHS) method has been used to produce a new class of active catalyst materials based on metals, metal oxides and spinels for various applications. The method is characterized by very fast processing times (of the order of minutes), relatively low preheating temperatures and very high reaction temperatures produced as a result of carefully designed exothermic reactions. A large range of materials have been produced and characterized by a variety of physico-chemical and mechanical tests. This review devoted to Catalytic properties of SHS products. A number of catalytically active materials all over the world have been identified which offer promise for applications ranging from oxidation of CO and hydrocarbons to reduction of NOx, methane dehydrogenation and other.

Recent advances in asymmetric catalysis. Synthetic applications to biologically active compounds

2001 ◽  
Vol 73 (2) ◽  
pp. 299-303 ◽  
Author(s):  
Jean Pierre Genet ◽  
Angela Marinetti ◽  
Virginie Ratovelomanana-Vidal
Keyword(s):  
Asymmetric Catalysis ◽  
High Efficiency ◽  
Catalytic Properties ◽  
Biologically Active ◽  
Preliminary Evaluation ◽  
Active Compounds ◽  
New Class ◽  
Industrial Synthesis ◽  
Asymmetric Hydrogenations ◽  
Apparent Stability

New chiral cationic ruthenium complexes have been used for the industrial synthesis of (+) -dihydrojasmonate. A new class of electron-rich C2-symmetric 2,4-disubstituted phosphetanes (CnrPHOS) was developed. Preliminary evaluation of their catalytic properties revealed high efficiency in rhodium and ruthenium-catalyzed asymmetric hydrogenations. A new stereochemical model is presented in which the phosphetane Rh-catalyzed hydrogenation follows an apparent stability-controlled mechanism.

scholarly journals New Class of IMP Cyclohydrolases in Methanococcus jannaschii

2002 ◽  
Vol 184 (5) ◽  
pp. 1471-1473 ◽  
Author(s):  
Marion Graupner ◽  
Huimin Xu ◽  
Robert H. White
Keyword(s):  
Escherichia Coli ◽  
Catalytic Properties ◽  
Sequence Similarity ◽  
Genetic Locus ◽  
Protein Product ◽  
Methanococcus Jannaschii ◽  
New Class

ABSTRACT The enzyme responsible for observed IMP cyclohydrolase activity in Methanococcus jannaschii was purified and sequenced: its genetic locus was found to correspond to gene MJ0626. The MJ0626 gene was cloned, and its protein product was expressed in Escherichia coli and shown to catalyze the cyclization of 5-formylamidoimidazole-4-carboxamide ribonucleotide to IMP. The enzyme has no sequence similarity to known enzymes, and its catalytic properties appear distinct from any characterized IMP cyclohydrolase. The purO gene for the enzyme is currently found only in the domain Archaea.

In Situ microscopy of the anodic etching of silicon

1995 ◽  
Vol 53 ◽  
pp. 232-233
Author(s):  
Frances M. Ross ◽  
Peter C. Searson
Keyword(s):  
Composite Structures ◽  
High Surface ◽  
High Surface Area ◽  
Chemical Properties ◽  
Selective Etching ◽  
Silicon On Insulator ◽  
Second Phase ◽  
Porous Layers ◽  
New Class ◽  
Porous Semiconductors

Porous semiconductors represent a relatively new class of materials formed by the selective etching of a single or polycrystalline substrate. Although porous silicon has received considerable attention due to its novel optical properties1, porous layers can be formed in other semiconductors such as GaAs and GaP. These materials are characterised by very high surface area and by electrical, optical and chemical properties that may differ considerably from bulk. The properties depend on the pore morphology, which can be controlled by adjusting the processing conditions and the dopant concentration. A number of novel structures can be fabricated using selective etching. For example, self-supporting membranes can be made by growing pores through a wafer, films with modulated pore structure can be fabricated by varying the applied potential during growth, composite structures can be prepared by depositing a second phase into the pores and silicon-on-insulator structures can be formed by oxidising a buried porous layer. In all these applications the ability to grow nanostructures controllably is critical.

Microstructure and reactivity of small metal particles: The role of Ce additives

1992 ◽  
Vol 50 (1) ◽  
pp. 318-319
Author(s):  
L.D. Schmidt ◽  
K. R. Krause ◽  
J. M. Schwartz ◽  
X. Chu
Keyword(s):  
Atmospheric Pressure ◽  
Noble Metals ◽  
Mixed Oxides ◽  
Catalytic Properties ◽  
Chemical Shifts ◽  
Catalytic Converter ◽  
Structural Evolution ◽  
Single Particles ◽  
Small Metal Particles

The evolution of microstructures of 10- to 100-Å diameter particles of Rh and Pt on SiO2 and Al2O3 following treatment in reducing, oxidizing, and reacting conditions have been characterized by TEM. We are able to transfer particles repeatedly between microscope and a reactor furnace so that the structural evolution of single particles can be examined following treatments in gases at atmospheric pressure. We are especially interested in the role of Ce additives on noble metals such as Pt and Rh. These systems are crucial in the automotive catalytic converter, and rare earths can significantly modify catalytic properties in many reactions. In particular, we are concerned with the oxidation state of Ce and its role in formation of mixed oxides with metals or with the support. For this we employ EELS in TEM, a technique uniquely suited to detect chemical shifts with ∼30Å resolution.

The microtubule associated protein (MAP) tau forms a new class of triple-stranded left-hand helical fibrous protein polymer

1992 ◽  
Vol 50 (1) ◽  
pp. 540-541
Author(s):  
G. C. Ruben ◽  
K. Iqbal ◽  
I. Grundke-Iqbal ◽  
H. Wisniewski ◽  
T. L. Ciardelli ◽  
...  
Keyword(s):  
Axial Ratio ◽  
Normal Structure ◽  
Paired Helical Filaments ◽  
Left Hand ◽  
New Class ◽  
Protein Polymer ◽  
Fibrous Protein ◽  
Protein Map ◽  
Neurotransmitter Transport ◽  
Alzheimer Neurofibrillary Tangles

In neurons, the microtubule associated protein, tau, is found in the axons. Tau stabilizes the microtubules required for neurotransmitter transport to the axonal terminal. Since tau has been found in both Alzheimer neurofibrillary tangles (NFT) and in paired helical filaments (PHF), the study of tau's normal structure had to preceed TEM studies of NFT and PHF. The structure of tau was first studied by ultracentrifugation. This work suggested that it was a rod shaped molecule with an axial ratio of 20:1. More recently, paraciystals of phosphorylated and nonphosphoiylated tau have been reported. Phosphorylated tau was 90-95 nm in length and 3-6 nm in diameter where as nonphosphorylated tau was 69-75 nm in length. A shorter length of 30 nm was reported for undamaged tau indicating that it is an extremely flexible molecule. Tau was also studied in relation to microtubules, and its length was found to be 56.1±14.1 nm.

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