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

2005 ◽  
Vol 30 (3) ◽  
pp. 145-213 ◽  
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.

Peran Badan Pengendalian Dampak Lingkungan dalam Pengendalian Dampak Pencemaran Kegiatan Industri di Kota Batam tahun 2011-2014

2015 ◽  
Vol 14 (1) ◽  
pp. 20
Author(s):  
Wan Asrida ◽  
Dian Arival Aryadana
Keyword(s):  
Environmental Impact ◽  
Environmental Pollution ◽  
Pollution Control ◽  
Control Agency ◽  
Accurate Method ◽  
Industrial Activity ◽  
Research Issues ◽  
Negative Effect ◽  
Research Show

This research is intended to find out the role of the regional environmental impact Control Agency of Batam City against the environmental problems that occur in industrial areas namely, Batam city, concerning sustainable development based upon the environment, the activities of the industry now aims to build an economic sector but has a negative effect that is the pollution of the environment. In this case in Batam city frequent occurrence of environmental pollution caused by industrial activity namely with disposal of waste which are not in place. This research is focused on environmental impact Control Agency area of Batam city authorities in the control of the environment . With the outline of the research issues namely how environmental impact Control Agency the role of the Regions in the control of pollution of the environment against industrial activity in Batam city in 2011-2014 and the factors restricting the role of the regional environmental impact Control Agency in controlling environmental pollution in Batam city in 2011-2014.Type of this research is a descriptive i.e. researchers provide a description and overview of the phenomenon or social symptoms examined by independent variables described in a systematic and accurate. Method of data collection is done by means of interviews and the documentation.The results of this research show that the role of environmental impact Control Agency area of Batam city in pollution control against industrial activity carried out according to its function but have not run well in accordance with the goals and targets that have been set. This is not in accordance with the duties and functions of the regional environmental impact Control Agency of Batam city, resulting in less the maximum role of Bapedalda itself in controlling pollution that occurred in Batam city. So it should be should be able to stake Bapedalda holder which is professional in the discharge of pollution control and must be capable of tackling the obstacles faced.

Private Capital Participation: Choices and Constraints

1992 ◽  
Vol 26 (7-8) ◽  
pp. 1915-1920
Author(s):  
D. Kinnersley
Keyword(s):  
Wastewater Treatment ◽  
Pollution Control ◽  
Private Capital ◽  
Role Of Government ◽  
Policy Choices ◽  
Government Role ◽  
Private Participation ◽  
The Government ◽  
Participation Frameworks

The scope for involving private capital participation in wastewater treatment and pollution control is attracting attention in a number of countries. After noting briefly some influences giving rise to this trend, this paper discusses frameworks in which such participation may be developed. In some aspects, there are choices available and it is essential to shape the private participation appropriately to the community's situation and problems, with due recognition of the hazards also involved. In other aspects, policy choices are more constrained, and there are requirements which it is suggested all private participation frameworks should provide for as clearly as possible. Effective private participation generally depends on re-designing and strengthening the role of government as the scale of its former role is reduced. Getting this re-design of the government role right is at least as important as making appropriate choices for format of private participation.

scholarly journals Oxidized LDLs as Signaling Molecules

Antioxidants ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1184
Author(s):  
Jean-Marc Zingg ◽  
Adelina Vlad ◽  
Roberta Ricciarelli
Keyword(s):  
Free Radicals ◽  
Cellular Response ◽  
Vascular System ◽  
Signaling Molecules ◽  
Scavenger Receptors ◽  
Physiological Relevance ◽  
Reactive Radicals ◽  
Accumulation Of Lipids

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.

scholarly journals Environmentally persistent free radicals are ubiquitous in wildfire charcoals and remain stable for years

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Gabriel Sigmund ◽  
Cristina Santín ◽  
Marc Pignitter ◽  
Nathalie Tepe ◽  
Stefan H. Doerr ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Free Radicals ◽  
Reactive Oxygen ◽  
Resonance Spectroscopy ◽  
Oxygen Species ◽  
Pyrogenic Carbon ◽  
Spin Resonance ◽  
Long Time ◽  
High Concentrations

AbstractGlobally landscape fires produce about 256 Tg of pyrogenic carbon or charcoal each year. The role of charcoal as a source of environmentally persistent free radicals, which are precursors of potentially harmful reactive oxygen species, is poorly constrained. Here, we analyse 60 charcoal samples collected from 10 wildfires, that include crown as well as surface fires in forest, shrubland and grassland spanning different boreal, temperate, subtropical and tropical climate. Using electron spin resonance spectroscopy, we measure high concentrations of environmentally persistent free radicals in charcoal samples, much higher than those found in soils. Concentrations increased with degree of carbonization and woody fuels favoured higher concentrations. Moreover, environmentally persistent free radicals remained stable for an unexpectedly long time of at least 5 years. We suggest that wildfire charcoal is an important global source of environmentally persistent free radicals, and therefore potentially of harmful reactive oxygen species.

scholarly journals Microstructure and Electromagnetic Properties of Ni-Zn-Co Ferrite up to 20 GHz

2016 ◽  
Vol 2016 ◽  
pp. 1-7 ◽  
Author(s):  
Charalampos Stergiou
Keyword(s):  
Wall Motion ◽  
Wave Attenuation ◽  
Domain Wall Motion ◽  
Electromagnetic Properties ◽  
Complex Permeability ◽  
Microwave Dielectric ◽  
Zn Ferrite ◽  
Spin Resonance ◽  
Production Stages

The present paper examines the relation between different developed microstructures and the microwave electromagnetic properties in Ni-Zn-Co ferrite. To this end, the Ni0.25Zn0.25Co0.5Fe2O4composition has been prepared with the conventional ceramic process with varied prefiringTP(750°C, 1000°C) and sinteringTStop temperatures (1200°C, 1250°C). When lower temperatures are applied in these production stages, incomplete microstructures with low density, higher porosity, or finer grains are achieved. On account of these features, the contributions of domain wall motion and spin rotation to the complex permeabilityμ⁎(f)move to higher frequencies, whereas microwave dielectric permittivityε⁎(f)is decreased. In particular in conjunction with the high Co content, the wall relaxation and spin resonance are interestingly forced to occur at 850 MHz and 8.05 GHz, respectively. Regarding the electromagnetic wave attenuation, the ferrite annealed at lower temperatures exhibits strong return loss peaks at higher frequencies, but without other performance improvement. We should notice that the variations in sintering temperatureTSyield the maximum changes in the recorded parameters, including the coercive field,μ⁎(f),andε⁎(f), indicating the inferior role of prefiringTPin Ni-Zn ferrite.

Electron spin resonance detection of heterogeneous reactions of Pigment Red 122

1990 ◽  
Vol 68 (4) ◽  
pp. 640-643
Author(s):  
Mary Jane Walzak ◽  
John R. Harbour
Keyword(s):  
Electron Spin Resonance ◽  
Electron Spin ◽  
Radical Anion ◽  
Heterogeneous Reactions ◽  
Resonance Spectroscopy ◽  
G Factor ◽  
Spin Resonance ◽  
Two Component ◽  
Induced Signal ◽  
Resonance Detection

Electron spin resonance spectroscopy (ESR) has been used to investigate the electrochemical and photolytic behaviour of particulate C.I. Pigment Red 122. Heterogeneous electrochemical reduction and oxidation of the pigment resulted in different reversible ESR signals with the radical cation giving a signal of ΔHpp = 2.3 G and g-factor of 2.0033 and the radical anion giving ΔHpp = 3.2 G and g-factor 2.0039. On exposure to light the inherent ESR signal, which was determined to be a two-component signal, increased in intensity by a factor of 2.4 but did not change in linewidth or g-factor. This light-induced signal was reversible and decayed to initial levels in the dark. The mechanism of these reactions is discussed. Keywords: ESR, pigment, electrochemistry, photo effects.

scholarly journals Pneumocystis Melanins Confer Enhanced Organism Viability

2006 ◽  
Vol 5 (6) ◽  
pp. 916-923 ◽  
Author(s):  
Crystal R. Icenhour ◽  
Theodore J. Kottom ◽  
Andrew H. Limper
Keyword(s):  
Fungal Pathogen ◽  
Pneumocystis Carinii ◽  
Environmental Stressors ◽  
Resonance Spectroscopy ◽  
Reverse Transcription Pcr ◽  
Spin Resonance ◽  
Opportunistic Fungal Pathogen ◽  
Adverse Environmental Conditions ◽  
Previous Identification

ABSTRACT Pneumocystis continues to represent an important opportunistic fungal pathogen of those with compromised immunity. Thus, it is crucial to identify factors that affect its viability and pathogenicity. We previously reported the first identification of melanins in Pneumocystis. In the present study, we sought to further characterize these components and define the function for these melanins. Melanins extracted from Pneumocystis and melanized Pneumocystis cells were analyzed by electron spin resonance spectroscopy, revealing spectra consistent with melanins from other fungi. Immunofluorescence assays using anti-melanin monoclonal antibodies showed that melanins are widely present across Pneumocystis host species, including mouse-, ferret-, and human-derived Pneumocystis organisms, as well as Pneumocystis carinii derived from rat. Using immunoelectron microscopy, melanins were found to localize to the cell wall and cytoplasm of P. carinii cysts, as well as to intracystic bodies within mature cysts. Next, the role of melanins on the maintenance of Pneumocystis viability was determined by using quantitative reverse transcription-PCR measurement of the heat shock protein mRNA under adverse environmental conditions. Using a new method to promote the melanization of Pneumocystis, we observed that strongly melanized Pneumocystis retained viability to a greater degree when exposed to UV irradiation or desiccation compared to less-pigmented organisms. These studies support our previous identification of Pneumocystis melanins across the genus, further characterize these Pneumocystis components, and demonstrate that melanins protect Pneumocystis from environmental stressors.

Surface Defects in Drawn Aluminum Magnet Wire

1975 ◽  
Vol 97 (1) ◽  
pp. 134-141 ◽  
Author(s):  
R. N. Wright ◽  
A. T. Male
Keyword(s):  
Defect Structure ◽  
Surface Characterization ◽  
Surface Defect ◽  
Potential Role ◽  
Surface Defects ◽  
Repair Process ◽  
Fine Surface ◽  
Magnet Wire ◽  
Characterization Studies

The fine surface defect structure of commercial EC grade aluminum magnet wire has been characterized and four basic component types have been identified. A grading system has been established for each of the component defects. Intermediate process surface characterization studies and laboratory drawing experiments have been performed to clarify the origin of the defects. The potential role of drawing lubrication in repairing or compounding the defect structure has been demonstrated and the mechanics of a drawing related repair process have been clarified through study of the effects of rod drawing on hardness indentations.

Sign in / Sign up

Export Citation Format

Share Document