ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1971.tb06118.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Abstract—–Pulse radiolysis has been used to excite the triplet states of β‐carotene (τ# 9μ sec) and lycopene (τ= 8μsec) in hexane solution, both in the presence and absence of naphthalene as a triplet sensitiser. The absorption spectra of both triplets have been measured in the range 430–550 nm and have thus been extended into the region of the corresponding singlet absorptions. The overlap of the triplet and singlet spectra is discussed in relation toin vivostudies. Extinction coefficients of 1.3±0.1 × 105l/mole cm for β‐carotene triplet 515 nm and 3.9±0.2 × 105l/mole cm for lycopene triplet at 525 nm were obtained. Isomerisation of the all‐transpolyenes used was detected and preliminary measurements indicate that the yield of isomerisation was greater than the triplet yield. The rate of triplet energy transfer from naphthalene to β‐carotene was estimated to be 1.5 × 1010l/mole sec. The corresponding value for lycopene was 1.4× 1010l/mole sec. The measured efficient quenching of triplet β‐carotene by oxygen may occur by an energy transfer mechanism, leading to the formation of singlet oxygen (1Δg. This would suggest that the triplet energy level of β‐carotene

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1971.tb06119.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Abstract—–The photosensitization of amino acids by proflavine is studied using the technique of electron spin resonance spectroscopy. The analysis of the line shape as a function of the incident microwave power (both in the presence and absence of oxygen) and the dependence of the numbers of free radicals on the intensity of the incident light allow one to suggest that two types of radicals are formed. One is formed by a biphotonic process, the nature of the radicals being the same as in the case of ionising radiation, while the other is probably the RO2radical formed as a result of photodynamic act

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1971.tb06120.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Abstract—–The repair of u.v. damaged DNA in HeLa cells can be detected using the alkaline sucrose gradient technique. As a result of pyrimidine dimer excision single strand breaks are produced in DNA of irradiated cells. Rejoining of these breaks occurs during an 8 hr post‐irradiation incubation period and is prevented by hydroxyurea and acriflavine. The inhibition of repair by hydroxyurea can be reversed by a mixture of all 4 deoxyribonucleosides at a concentration that does not reverse the inhibition of total DNA synt

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1971.tb06121.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Abstract—–Irradiation of hexachlorophene in absolute ethanol yields a series of dechlorinated bisphenols resulting from loss of chlorine at theorthoandparapositions relative to the hydroxy groups. The two primary photoproducts. 2.2′‐dihydroxy‐3,3′, 5,6,6′‐pentachlorodiphenylmethane and 2,2′‐dihydroxy‐3,5,5′, 6,6′‐pentachlorodiphenylmethane were identifi

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1971.tb06122.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

摘要:

Abstract—–Photochemistry of thymidine in the solid state has been investigated. Four isomers of the cyclobutane‐type thymidine dimer, two bimolecular addition products with u.v. absorbance maxima above 300 nm, (the formation of which involves the C=C and C=O groups of adjacent thymine residues) and 5‐thyminyl‐5.6 dihydrothymine (TDHT) (formed by the addition of a thyminyl radical at the C5position of a thymyl radical) were isolated. TDHT was found to be the major photoproduct. The results are compared with those for thymidine irradiated in the fro

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1971.tb06123.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1971.tb06124.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1971.tb06125.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1971.tb06126.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY

ISSN:0031-8655    

DOI:10.1111/j.1751-1097.1971.tb06127.x

出版商:Blackwell Publishing Ltd    

年代:1971

数据来源: WILEY