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1.
Photodynamic therapy removes unwanted or harmful cells by overproduction of reactive oxygen species (ROS). Fractionated light delivery in photodynamic therapy may enhance the photodynamic effect in tumor areas with insufficient blood supply by enabling the reoxygenation of the treated area. This study addresses the outcome of fractionated irradiation in an in vitro photodynamic treatment (PDT) system, where deoxygenation can be neglected. Our results show that fractionated irradiation with light/dark intervals of 45/60 s decreases ROS production and cytotoxicity of PDT. This effect can be reversed by addition of 1,3-bis-(2-chlorethyl)-1-nitrosurea (BCNU), an inhibitor of the glutathione reductase. We suggest that the dark intervals during irradiation allow the glutathione reductase to regenerate reduced glutathione (GSH), thereby rendering cells less susceptible to ROS produced by PDT compared with continuous irradiation. Our results could be of particular clinical importance for photodynamic therapy applied to well-oxygenated tumors. 相似文献
2.
Benno Buchser Horst H. E. Leipholz 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1973,24(2):255-269
This paper investigates the influence of the mass distribution on the stability behaviour of pinned-pinned and clamped-clamped rods, subjected to a nonconservative, constant distribution of follower forces. It shows that divergence buckling loads do always exist, are independent of the particular mass distribution and determine the stability behaviour for positive loads. For negative follower forces however, the systems are either stable or show instability due to flutter. Both cases can be obtained by a suitable choice of the mass distribution. Furthermore, the paper gives bounds for the divergence buckling loads and the flutter loads.
Zusammenfassung Die Autoren untersuchen den Einfluss der Massenverteilung auf das Stabilitätsverhalten von beidseitig gelenkig gelagerten und beidseitig eingespannten elastischen Stäben, die einer gleichmässig verteilten, nichtkonservativen, mitgehenden Last unterworfen sind. Es zeigt sich, dass in allen Fällen Knicklasten vorhanden sind, die sich durch Divergenz ergeben, die von der besonderen Massenverteilung unabhängig sind und die im Bereich positiver Lasten für das Stabilitätsverhalten massgeblich sind. Für negative mitgehende Lasten sind die Systeme jedoch entweder stabil oder sie werden durch Flattern instabil. Beide diese Fälle können durch eine geeignete Wahl der Massenverteilung verwirklicht werden. Schliesslich enthält die Arbeit Schranken für die Divergenz-Knicklasten und für die Lasten, die zum Flattern führen.相似文献
3.
We show that frequency and intensity noise in a Nd:YAG laser are correlated to a high degree and can be traced to the same underlying cause, namely, power fluctuations of the pump source. Because of this correlation, simultaneous suppression of frequency and intensity noise by 30 dB is achieved by means of a single actuator, the pump power. 相似文献
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Three new lacunar-type derivatives of β-unsubstituted dibenzotetraaza[14]annulene have been synthesized along with a range of their open-chain pendant group containing counterparts. The crystal structures of two representative products have been determined and the noncovalent interactions explored. A number of C-H?π and π?π interactions involving aliphatic chains and aromatic regions of the macrocycle have been evidenced. The relative ease and high yield of lacunization are suggested to be largely due to self-assembly processes, driven by favorable noncovalent interactions between reacting units. 相似文献
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The power noise of a cw Nd:YAG laser system was measured at radio frequencies using the optical ac coupling technique. An additional mode cleaner in the setup allowed a high optical ac coupling amplification of 62.3. For the first time, to our knowledge, a sensitivity of 1.1×10?1? Hz(-1/2) relative power noise was achieved corresponding to an equivalent detected photocurrent of 32 A. High precision optics experiments can utilize this scheme to improve the sensitivity of their photodetectors. 相似文献
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Elena Froner Roberta Adamo Zeno Gaburro Benno Margesin Lorenzo Pavesi Adelio Rigo Marina Scarpa 《Journal of nanoparticle research》2006,8(6):1071-1074
Aqueous solutions of silicon nanocrystals have been obtained, by sonication, from porous Si (p-Si) aged in air for various times. The photoluminescence of these solutions changes with the aging time of p-Si. These changes correlate with nanocrystal core dimensions, i.e. with the oxidation of the nanocrystals. Infrared spectra show that the reaction with water depends on the age of the starting p-Si sample, since the native superficial oxide layer on p-Si inhibits these reactions. 相似文献