Role of Interstitial Voids in Oxides on Formation and Stabilization of Reactive Radicals:  Interstitial HO2Radicals in F2-Laser-Irradiated Amorphous SiO2

Levels of oxidized low-density lipoproteins (oxLDLs) are usually low in vivo but can increase whenever the balance between formation and scavenging of free radicals is impaired. Under normal conditions, uptake and degradation represent the physiological cellular response to oxLDL exposure. The uptake of oxLDLs is mediated by cell surface scavenger receptors that may also act as signaling molecules. Under conditions of atherosclerosis, monocytes/macrophages and vascular smooth muscle cells highly exposed to oxLDLs tend to convert to foam cells due to the intracellular accumulation of lipids. Moreover, the atherogenic process is accelerated by the increased expression of the scavenger receptors CD36, SR-BI, LOX-1, and SRA in response to high levels of oxLDL and oxidized lipids. In some respects, the effects of oxLDLs, involving cell proliferation, inflammation, apoptosis, adhesion, migration, senescence, and gene expression, can be seen as an adaptive response to the rise of free radicals in the vascular system. Unlike highly reactive radicals, circulating oxLDLs may signal to cells at more distant sites and possibly trigger a systemic antioxidant defense, thus elevating the role of oxLDLs to that of signaling molecules with physiological relevance.

Download Full-text

Fundamental Role of Creation and Activation in Radiation-Induced Defect Production in High-Purity Amorphous SiO2

Physical Review Letters ◽

10.1103/physrevlett.76.2926 ◽

1996 ◽

Vol 76 (16) ◽

pp. 2926-2929 ◽

Cited By ~ 53

Author(s):

V. A. Mashkov ◽

Wm. R. Austin ◽

Lin Zhang ◽

R. G. Leisure

Keyword(s):

High Purity ◽

Defect Production ◽

Amorphous Sio2 ◽

Radiation Induced

Download Full-text

Radiation damage and the role of structure in amorphous SiO2

Nuclear Instruments and Methods in Physics Research Section B Beam Interactions with Materials and Atoms ◽

10.1016/0168-583x(90)90706-z ◽

1990 ◽

Vol 46 (1-4) ◽

pp. 244-251 ◽

Cited By ~ 47

Author(s):

R.A.B. Devine

Keyword(s):

Radiation Damage ◽

Amorphous Sio2

Download Full-text

The role of impurities in the irradiation induced densification of amorphous SiO2

Journal of Physics Condensed Matter ◽

10.1088/0953-8984/22/25/255403 ◽

2010 ◽

Vol 22 (25) ◽

pp. 255403 ◽

Cited By ~ 6

Author(s):

G Buscarino ◽

S Agnello ◽

F M Gelardi ◽

R Boscaino

Keyword(s):

Amorphous Sio2

Download Full-text

Reactive Radicals on Reactive Surfaces: Heterogeneous Processes in Catalysis and Environmental Pollution Control

Progress in Reaction Kinetics and Mechanism ◽

10.3184/007967405779134038 ◽

2005 ◽

Vol 30 (3) ◽

pp. 145-213 ◽

Cited By ~ 29

Author(s):

Christopher J. Rhodes

Keyword(s):

Pollution Control ◽

Surface Defects ◽

Practical Investigations ◽

Heterogeneous Reactions ◽

Molecular Surface ◽

Spin Resonance ◽

Heterogeneous Processes ◽

Tunnelling Microscopy ◽

Reactive Radicals

Many reactions that occur on solid surfaces are mediated by free radicals. A review is presented of both mechanistic and practical investigations in relation to catalysis and environmental applications. The review begins with actual imaging of surface adsorbed reactive radicals using scanning tunnelling microscopy (STM), and then discusses a range of examples, mainly as underpinned by electron spin resonance (ESR) measurements. Included are surface defects and their reactions, studies of the redox behaviour of zeolites, and the use of radicals adsorbed in zeolites as molecular surface probes of diffusion and reactivity within these important materials. Photocatalysis, mainly using TiO2-based materials, is reviewed both from the fundamental perspective and in terms of some practical examples relating to pollution control. Other reactive oxide surfaces are considered, including silica, and the nature of paramagnetic centres that may be induced thereon by a variety of activation procedures. Evidence is presented for the formation of radical species during heterogeneous reactions on metal surfaces. Finally, the role of free radical generation in creating and modifying polymer and nanomolecular systems is discussed, and the health implications of the ability of some solids such as quartz to generate reactive oxygen radicals in contact with biological media.

Download Full-text