Home  About us  Contact
 

Structural Modulation (structural + modulation)

Distribution by Scientific Domains
Chemistry80%

Selected Abstracts

Novel Structural Modulation in Ceramic Sensors Via Redox Processing in Gas Buffers

INTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 3 2006
Abdul-Majeed Azad
High selectivity, enhanced sensitivity, short response time, and long shelf-life are some of the key features sought in the solid-state ceramic-based chemical sensors. As the sensing mechanism and catalytic activity are predominantly surface-dominated, benign surface features in terms of small grain size, large surface area, high aspect ratio and, open and connected porosity, are required to realize a successful material. In order to incorporate these morphological features, a technique based on rigorous thermodynamic consideration of the metal/metal oxide coexistence is described. By modulating the oxygen partial pressure across the equilibrium M/MO proximity line, formation and growth of new oxide surface on an atomic/submolecular level under conditions of "oxygen deprivation," with exotic morphological features, has been achieved in potential sensor materials. This paper describes the methodology and discusses the results obtained in the case of potential semiconducting ceramic oxide-based carbon monoxide and hydrogen sensors with enhanced characteristics. [source]

Structural Modulation of Solid-State Emission of 2,5-Bis(trialkylsilylethynyl)-3,4-diphenylsiloles,

ANGEWANDTE CHEMIE, Issue 41 2009
Zujin Zhao Dr.
Gemeinsam stark , so lautet das Motto für neue Silol-Luminogene, die in festen Aggregaten stärker emittieren als in Form isolierter Moleküle. Die Emission im festen Zustand lässt sich über die Molekülstruktur einstellen: Sperrige Substituenten schwächen die intermolekularen Wechselwirkungen und schränken die Molekülrotation ein, woraus eine Blauverschiebung und eine stark gesteigerte Effizienz der Emission resultieren (siehe die Beispiele). [source]

Reversible Structural Modulation of Fe,Pt Bimetallic Surfaces and Its Effect on Reactivity

CHEMPHYSCHEM, Issue 7 2009
Teng Ma
Abstract Tunable surface: The surface structure of the Fe,Pt bimetallic catalyst can be reversibly modulated between the iron-oxide-rich Pt surface and the Pt-skin structure with subsurface Fe via alternating reduction and oxidation treatments (see figure). The regenerated active Pt-skin structure is active in reactions involving CO and/or O. [source]

Bioluminescent Probes of Sulfatase Activity

CHEMBIOCHEM, Issue 15 2010
Jason S. Rush
Lighting up sulfatases: A panel of bioluminescent sulfatase reporters have been developed that can be used to investigate sulfatase activity in both human and prokaryotic cell samples. Structural modulation allowed selective probe activation by particular enzymes. This strategy has potential application in common clinical imaging modalities, such as MRI and PET. [source]

Synthesis and Stability in Biological Media of 1H -Imidazole-1-carboxylates of ROS203, an Antagonist of the Histamine H3 Receptor

CHEMISTRY & BIODIVERSITY, Issue 1 2008
Mirko Rivara
Abstract A series of carbamate derivatives of the H3 antagonist ROS203 (1) were prepared, and their lipophilicity and steric hindrance were modulated by introducing linear or branched alkyl chains of various lengths. In vitro stability studies were conducted to evaluate how structural modulations affect the intrinsic reactivity of the carbamoyl moiety and its recognition by metabolic enzymes. Linear alkyl carbamates were the most susceptible to enzymatic hydrolysis, with bioconversion rates being higher in rat liver and plasma. Chain ramification significantly enhanced the enzymatic stability of the set, with two derivatives (1g and 1h) being more stable by a factor of 8,40 than the ethyl carbamate 1a. Incubation with bovine serum albumin (BSA) showed a protective role of proteins on chemical and porcine-liver esterase (PLE)-catalyzed hydrolysis. Ex vivo binding data after i.v. administration of 1h revealed prolonged displacement of the labeled ligand [3H]-(R)- , -methylhistamine ([3H]RAMHA) from rat-brain cortical membranes, when compared to 1. However, the high rates of bioconversion in liver, as well as the chemical instability of 1h, suggest that further work is needed to optimize the enzymatic and chemical stability of these compounds. [source]