CCXXII.—The decomposition of ozone by light of the visible spectrum

Griffith, R. O.; Shutt, W. J.

doi:10.1039/ct9211901948

Cited by 56 publications

(78 citation statements)

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“…(Since the concentration of inhibitor required to arrest growth depends upon the phase in the life history of the culture at which it is admitted, a series of observations was made.) Griffith & Schutt ( 1921), the procedure of the latter workers being followed exactly in assembling the electrode. * The arrangement of the apparatus is depicted diagrammatically in Fig.…”

Section: Introductionmentioning

confidence: 99%

Inhibition of bacterial growth by pure ozone in the presence of nutrients

Ingram

Haines

1949

J. Hyg.

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Data are given showing the concentration of pure ozone required to inhibit the growth of, and to destroy, various micro-organisms when growing on agar, in nutrient broth, a synthetic medium, or simply suspended in water. The following is shown:1. Different organisms vary in their susceptibility towards this gas. Achromobacter and Pseudomonas strains, such as occur on chilled meat, are the most resistant. On the whole, mould fungi are about as susceptible as bacteria.2. Very much higher concentrations are required to arrest established growth than can be used if inoculation and admission of inhibitor are coincident.3. Lower concentrations are inhibitory at lower temperatures. These results are ascribed to dissipation of the ozone by combination with products of bacterial metabolism. It seems that any factor which diminishes growth will augment the effectiveness of ozone.4. Comparatively small concentrations (less than 10 p.p.m.) suffice to destroy bacteria suspended in water. Somewhat larger concentrations inhibit growth in a synthetic medium.5. Still larger quantities (several hundred p.p.m.) are required in nutrient broth.6. Nutrient broth treated with ozone will support little or no bacterial growth, due to change of pH, growth taking place slowly if the pH is restored to its original value. Inhibition of growth in such a medium is therefore a complex process depending in part upon the secondary effects of decomposition of the medium.7. To kill them, bacteria require still more ozone (in some cases several thousand p.p.m.) if growing on agar. These results are ascribed to combination of ozone with the supporting medium.8. When applied to organisms growing on food, combination with ozone not only spoils the food, but it makes it difficult to interpret the effect on the microbes in terms of the ozone applied.9. The inhibitory concentrations are higher than humans can tolerate.10. Ozone destroys the dehydrogenating enzymes of the cell, and it is suggested that its germicidal action may be partly due to interference with cellular respiration.The work described in this paper was carried out as part of the programme of the Food Investigation Organization of the Department of Scientific and Industrial Research.

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Section: Introductionmentioning

confidence: 99%

Inhibition of bacterial growth by pure ozone in the presence of nutrients

Ingram

Haines

1949

J. Hyg.

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“…Considering the elastic energy released by the crack and the interfacial energy gained in creating it, one can show that a crack of length a 0 becomes unstable for stresses larger than c K c = a 0 p , where the critical stress intensity factor K c EG c p is a function of the fracture toughness G c and the elastic modulus E [10]. The Griffith argument has been generalized by Bazant to quasibrittle materials [4], postulating that when the FPZ is present, the crack length a 0 should increase by an additional length scale , yielding…”

Section: Role Of Disorder In the Size Scaling Of Materials Strengthmentioning

confidence: 99%

Role of Disorder in the Size Scaling of Material Strength

2008

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We study the sample size dependence of the strength of disordered materials with a flaw, by numerical simulations of lattice models for fracture. We find a crossover between a regime controlled by the fluctuations due to disorder and another controlled by stress-concentrations, ruled by continuum fracture mechanics. The results are formulated in terms of a scaling law involving a statistical fracture process zone. Its existence and scaling properties are only revealed by sampling over many configurations of the disorder. The scaling law is in good agreement with experimental results obtained from notched paper samples.

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“…According to the theory of Linear-Elastic Fracture Mechanics [12,13] (LEFM), if a sharp crack is located in an area of tensile stress, as illustrated by the dashed line in Figure 6a, the onset of crack propagation will be controlled by three parameters. They are a) the geometry of the initial crack, b) the magnitude of the applied load and hence the tensile stress perpendicular to the crack plane and c) the fracture toughness K IC of the material.…”

Section: Onset Of Crack Propagationmentioning

confidence: 99%

“…The second part focuses on the cleavage of semiconductors after the introduction of an initial defect during scratching. Even though the concepts of fracture mechanics have been strongly established since the pioneering work of Griffith [12] and Irwin [13] in the late fifties, physicists have only recently been interested in the fundamental mechanisms governing crack propagation in brittle materials. [14,15] In particular, for crack propagating above a certain critical speed, crack branching is observed, [2] which leads to surface roughening.…”

Section: Introductionmentioning

confidence: 99%

Cleavage Fracture of Brittle Semiconductors from the Nanometre to the Centimetre Scale

et al. 2005

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The objective of this paper is to present the fundamental phenomena occurring during the scribing and subsequent fracturing process usually performed when preparing surfaces of brittle semiconductors. In the first part, an overview of nano‐scratching experiments of different semiconductor surfaces (InP, Si and GaAs) is given. It is shown how phase transformation can occur in Si under a diamond tip, how single dislocations can be induced in InP wafers and how higher scratching load of GaAs wafer leads to the apparition of a crack network below the surface. A nano‐scratching device, inside a scanning electron microscope (SEM), has been used to observe how spalling (crack and detachment of chips) and/or ductile formation of chips may happen at the semiconductor surface. In the second part cleavage experiments are described. The breaking load of thin GaAs (100) wafers is directly related to the presence of initial sharp cracks induced by scratching. By performing finite element modelling (FEM) of samples under specific loading conditions, it is found that the depth of the median crack below the scratch determines quantitatively the onset of crack propagation. By carefully controlling the position and measuring the force during the cleavage, it is demonstrated that crack propagation through a wafer can be controlled. Besides, the influence of the loading configuration on crack propagation and on the cleaved surface quality is explained.

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CCXXII.—The decomposition of ozone by light of the visible spectrum

Cited by 56 publications

References 0 publications

Inhibition of bacterial growth by pure ozone in the presence of nutrients

Inhibition of bacterial growth by pure ozone in the presence of nutrients

Role of Disorder in the Size Scaling of Material Strength

Cleavage Fracture of Brittle Semiconductors from the Nanometre to the Centimetre Scale

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