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T I Quickenden

Publications and source records attributed to T I Quickenden.

18 recordsLinked to original sources
PubMed2000

Luminescent photoproducts in UV-irradiated ice.

This Account describes the near-UV and visible luminescences emitted from crystalline, polycrystalline, and amorphous ices as a result of excitation by UV light. Vibrationally resolved, short-lived luminescence around 340 nm arises from excited O(2) formed by the reaction of two O atoms. Long-lived luminescence around 420 nm is tentatively assigned to a spin-forbidden (4)sigma(-) --> X(2)Pi transition of OH. This Account gives a history of the research into this little-known phenomenon, places it in the context of other spectroscopic studies of gaseous and solid water, and proposes future directions for the work.

Ice↗
PubMed1994

Does low-intensity He-Ne laser radiation produce a photobiological growth response in Escherichia coli?

A photobiological study was carried out on the bacterium Escherichia coli in order to determine whether stimulation of growth occurred after irradiation of an inoculum with coherent red light. No enhancement or inhibition of growth was observed for cultures of the bacterium following irradiation of inocula with a Helium-neon laser (continuous wave, lambda = 632.8 nm) at irradiances of 7.7 x 10(15) and 1.8 x 10(16) photons cm-2 s-1 using fluences of 4.5 x 10(-1) and 4.5 J cm-2 at each irradiance. Bacterial growth in irradiated and control cultures was monitored during a growth period of ca 2 h using a viable count technique after inocula in the early exponential phase had been diluted with fresh growth medium. These results do not provide support for the work of Karu et al. (1983, Nuov. Cim. 2D, 1138-1144), and Tiphlova and Karu (1988, Photochem. Photobiol. 48, 467-471), which appear to show substantial enhancement of E. coli growth under these conditions.

Colony Count, Microbial↗
PubMed1993

Attempted biostimulation of division in Saccharomyces cerevisiae using red coherent light.

Replicate cultures of the yeast Saccharomyces cerevisiae were irradiated with 632.8 nm coherent light from He-Ne lasers at irradiances of 6.5 x 10(15) and 1.0 x 10(16) photons s-1 cm-2. Irradiation periods ranged from 0 to 652 min, and cultures were grown until well into the exponential phase. Unirradiated control cultures were grown alongside the irradiated cultures under otherwise identical conditions. The extents of growth in the control and irradiated cultures were compared spectrophotometrically at the end of each experiment. Contrary to the expectations of Karu et al. (e.g. Karu, 1988, Lasers Life Sci. 2, 53-74) no growth enhancement was found in the irradiated cultures, but a mild inhibitory effect was observed.

Light↗
PubMed1992

Luminescence from the yeast Candida utilis and comparisons across three genera.

Weak luminescence was detected from oxygenated liquid cultures of the yeast Candida utilis during two stages of its growth cycle. The first period of emission occurred during the exponential phase of growth and comprised an ultraviolet band (270-390 nm; ca 19 photons s-1 cm-2 of culture surface) and a visible band (450-620 nm; ca 68 photons s-1 cm-2). The second period of emission occurred late in the stationary phase of growth and was comprised almost entirely of a visible region band (450-620 nm; 6.8 x 10(2) photons s-1 cm-2). No luminescence was observed when the yeast was grown anaerobically. These observations are compared with those previously obtained for two other yeasts, Saccharomyces cerevisiae and Schizosaccharomyces pombe. The ratios of the intensities of the blue/red emissions in the stationary phase luminescences correlated with the ratio of the saturated/unsaturated lipid content for the three yeasts. This result provided further support for the claim that the stationary phase luminescence arises from the reactions associated with lipid peroxidation. A number of previously suggested sources of the exponential phase luminescence are discussed and rejected. Oxidative side reactions accompanying protein synthesis remain a possible source of that emission.

Candida↗
PubMed1991

Luminescence spectra of exponential and stationary phase cultures of respiratory deficient Saccharomyces cerevisiae.

The spectral distributions of the luminescences emitted by the respiratory-deficient mutant of Saccharomyces cerevisiae and the normal yeast have been determined during the exponential phase of growth and during the stationary phase. The respiratory-deficient mutant gave a more intense emission in the visible region than did the normal yeast, but the UV intensities from the two yeasts did not differ greatly. These differences were explained in terms of higher O2- concentrations in the respiratory-deficient mutant which lead to enhanced visible region chemiluminescence from lipid peroxidation reactions.

Luminescent Measurements↗
PubMed1989

An attempt to stimulate cell division in Saccharomyces cerevisiae with weak ultraviolet light.

Liquid cultures of the yeast Saccharomyces cerevisiae were irradiated with weak light having irradiances ranging from ca. 1 X 10(2) to 5 X 10(9) photons cm-2 s-1 and at wavelengths ranging from 200 to 700 nm. When particular care was taken to control the temperature of the cultures and the flow rate of oxygen, no evidence was obtained for stimulation of either yeast growth or division by the incident light. These results do not support the claims of early workers that very low intensity uv light can stimulate cell division in living organisms.

Cell Division↗
PubMed1987

The effect of cosmic-ray shielding on the ultraweak bioluminescence emitted by cultures of Escherichia coli.

Neither the growth of Escherichia coli nor its associated luminescence was significantly affected when cultures were shielded from the soft component of cosmic rays. The study included experiments in which the cultures were shielded intermittently during their two periods of luminescence emission and experiments in which the cultures were continuously shielded throughout their entire growth cycle. These results do not support previous suggestions that the ultraweak bioluminescences from living organisms might be cosmic-ray-excited fluorescences induced in certain biological molecules synthesized during the various stages of growth.

Cosmic Radiation↗
PubMed1986

A critical examination of the bioplasma hypothesis.

The hypothesis of Zon (Physiol. Chem. and Physics 11, 501-506 (1979); 12, 357-364 (1980] that regions of semiconduction within living organisms may exhibit plasma behaviour is shown to be most unlikely. Although charge carrier concentrations may be acceptable, calculated Debye lengths are shown to be only marginally acceptable and calculated plasma frequencies are not sufficiently high to ensure that charge carrier motions are governed by electrical and magnetic forces rather than hydrodynamic considerations. For the latter reason, conventional semiconductors do not exhibit plasma behaviour except close to absolute zero and if they are free from impurities and lattice disorder. The experimental evidences presented for the existence of biological plasma (bioplasma) from the areas of Kirlian photography, mitogenetic radiation, acupuncture and studies of biological fields, are largely explainable in conventional terms without invoking the existence of biological plasma.

Acupuncture Therapy↗
PubMed1985

An attempt to stimulate mitosis in Saccharomyces cerevisiae with the ultraviolet luminescence from exponential phase cultures of this yeast.

Neither cell division nor growth of Saccharomyces cerevisiae were stimulated by the ultraviolet luminescence produced by adjacent exponential phase cultures of the yeast. The study included experiments in which the inocula (density = 5 X 10(7) cells cm-3) were irradiated and in which lag phase cultures (densities = 1 X 10(6) or 5 X 10(6) cells cm-3) were irradiated for 30 min with the yeast luminescence. These results do not support the claims of earlier workers that dividing cells can stimulate mitosis in optically coupled cultures by the so-called "mitogenetic effect."

Cell Division↗
PubMedDate not supplied

Electrogenerated chemiluminescence from violanthrone.

Violanthrone, an emitter of exceptionally bright chemiluminescence, was examined in dimethylformamide solution to determine whether it also emits particularly bright electrogenerated chemiluminescence (ECL). The ECL measurements were carried out using a cycled potential which was applied to platinum electrodes. At the maximum sweep rate of 80 V s-1 available, the intensity of the violanthrone ECL was still increasing with sweep rate and was c. 56% of that from rubrene, a bright, commonly used emitter of ECL. Furthermore, assuming that the emission arises from radical anion-cation recombination, the sweep rate dependence showed that the least stable radical ion (probably the cation) decays with a half-life shorter than 0.2 s.

Benzopyrenes↗
PubMedDate not supplied

Increasing the specificity of the forensic luminol test for blood.

It is shown that the presumptive luminol chemiluminescence test for the presence of traces of blood can be made more determinative by measuring the peak emission wavelength of the luminol chemiluminescence. When sprayed onto a surface containing traces of human haemoglobin, a 1 g/L solution of aqueous luminol containing 7 g/L sodium perborate gives an emission peak at 455 +/- 2 nm, whereas the same mixture gives an emission peak at 430 +/- 3 nm when sprayed onto a surface containing traces of sodium hypochlorite (household bleach). This spectral difference can readily be determined using spectroscopic equipment that either scans the spectrum before significant luminescence decay occurs or corrects the spectrum for the effects of any decay. It was found that bovine haemoglobin and human haemoglobin showed no significant spectral differences.

Animals↗
PubMedDate not supplied

A study of common interferences with the forensic luminol test for blood.

A wide range of domestic and industrial substances that might be mistaken for haemoglobin in the forensic luminol test for blood were examined. The substances studied were in the categories of vegetable or fruit pulps and juices; domestic and commercial oils; cleaning agents; an insecticide; and various glues, paints and varnishes. A significant number of substances in each category gave luminescence intensities that were comparable with the intensities of undiluted haemoglobin, when sprayed with the standard forensic solution containing aqueous alkaline luminol and sodium perborate. In these cases the substance could be easily mistaken for blood when the luminol test is used, but in the remaining cases the luminescence intensity was so weak that it is unlikely that a false-positive test would be obtained. In a few cases the brightly emitting substance could be distinguished from blood by a small but detectable shift of the peak emission wavelength. The results indicated that particular care should be taken to avoid interferences when a crime scene is contaminated with parsnip, turnip or horseradish, and when surfaces coated with enamel paint are involved. To a lesser extent, some care should be taken when surfaces covered with terracotta or ceramic tiles, polyurethane varnishes or jute and sisal matting are involved.

Animals↗
PubMedDate not supplied

A comprehensive experimental study of industrial, domestic and environmental interferences with the forensic luminol test for blood.

This paper presents the fi rst comprehensive and quantitative study of substances that interfere with the forensic luminol test for blood. Two hundred and fifty substances have been selected on the basis of modern lifestyles and of contiguity with crime scenes. The intensity of the chemiluminescence produced by each substance has been measured relative to that of haemoglobin and the peak wavelength shift has also been determined. The following is a short list of nine substances that produce chemiluminescence intensities comparable with that of haemoglobin: turnips, parsnips, horseradishes, commercial bleach (NaClO), copper metal, some furniture polishes, some enamel paints, and some interior fabrics in motor vehicles. Care needs to be taken when the luminol test for blood is used in the presence of these substances.

Blood Chemical Analysis↗