Time-optimal control of a parabolic system with time lags given in the integral form

In this paper the time-optimal control problem for a distributedparabolic system in which time lags appear in the integral formboth in the state equation and in the boundary condition ispresented. The particular properties of the optimal controlare discussed.     

A Note on Sampling from Combinations of Distributions

A rejection technique is described for sampling from a combinationof distributions with negative weights for some of the components.     

The Urbanik generalized convolutions in the non-commutative probability and a forgotten method of constructing generalized convolution

The paper deals with the notions of weak stability and weak generalized convolution with respect to a generalized convolution, introduced by Kucharczak and Urbanik. We study properties of such objects and give examples of weakly stable measures with respect to the Kendall convolution. Moreover, we show that in the context of non-commutative probability, two operations: the q-convolution and the (q,1)-convolution satisfy the Urbanik??s conditions for a generalized convolution, interpreted on the set of moment sequences. The weak stability reveals the relation between two operations.     

The power and limits of the Judd—Ofelt theory: a case of Pr3+ and Tm3+ acetates and dipicolinates

Electronic absorption spectra of crystals and solutions of praseodymium and thulium acetates and dipicolinates are reported. The influence of spectral properties of both ligands on intensities of the f—f transitions in the crystals studied is discussed. In the near-IR region, overtone vibrations of ligands are strongly coupled with the f—f transitions, particularly with the hypersensitive ones. In the UV spectral range, absorption bands of the π → π?, n → π? and possible charge transfer of metal ? ligand transitions affect f—f transitions and should also be taken into account. The phenomenological Judd—Ofelt parameters evaluated for praseodymium complexes in solution and crystals are meaningless, because no set of intensities unbiased by ligand transitions and/or neighbouring f-d configurations is available. For Tm³⁺ compounds the Judd-Ofelt analysis has given quite good results, however no significant influence of the metal ion environment changes on the Ωλ parameters can be observed.     

Some New Results on the Eigenvector Centrality

In this article we establish new results on the components of the principal eigenvector in an undirected graph. Those results are particularly significant in relation to the concept of centrality in social networks. In particular degree centrality and eigenvector centrality are compared. We find further conditions, based on the spectral radius, on which nodes with highest degree centrality are also the most eigencentral.     

X-ray spectrometry for preventive conservation of cultural heritage

Analytical chemistry does play a key role in the chemical characterization of the environment and it appears that X-ray spectrometry, in its many forms, is one of the most relevant analytical techniques in preventive conservation, as it is in cultural heritage research in general. X-ray spectrometry has indeed been the method of choice for the characterization of the inorganic composition of atmospheric aerosols, for a long time.     

1H-INDENYLFURAN AND THIOPHENE DERIVATIVES– A NEW CLASS OF SINGLET OXYGEN SENSITIZERS

Abstract— Photophysical and photochemical properties of 1H-indenylfuran and thiophene derivatives were studied. UV spectra showed that all the compounds tested absorbed UV light in the region 350–380 nm. The fluorescence spectra of 4a-e showed bands in the region 410–470 nm and quantum yields (φ_F) in the range 0.25–0.88. Attempts to calculate the triplet energy of 4a-e failed except for 4c and 4d , which showed E_T= 43–44 kcal mol^-1. These compounds are a new class of singlet oxygen sensitizers. The sensitized reaction of 2,5-dimethylfuran with singlet oxygen was followed showing that 4a and 4e are more reactive than α-terthiophene (4.0 and 2.5 times respectively), while the other compounds show the same reactivity as 1 . This behavior can be explained considering the different intersystem crossing quantum yields of compounds 4a-e . Diazabicyclo[2. 2. 2]octane is a quencher of singlet oxygen in this reaction, while we can exclude superoxide ion formation using the photooxidation of α, α-dimethylstilbene.     

MOUSE SKIN PHOTOSENSITIZATION WITH BENZOPORPHYRIN DERIVATIVES AND PHOTOFRIN®: MACROSCOPIC AND MICROSCOPIC EVALUATION

A comparative study, at both the macroscopic and microscopic level, of skin photosensitivity caused by four isomeric forms of benzoporphyrin derivative (BPD) has been carried out, and compared to effects of Photofrin. Animals injected intravenously with BPD analogues and exposed to light 3 h later showed extensive photosensitivity. Animals receiving the monoacid derivatives of BPD (BPD-MA and BPD-MB) showed markedly more photosensitivity than those receiving the diacid derivatives (BPD-DA and BPD-DB). Animals receiving BPD analogues which were exposed to light 24 h or more later showed only minimal reactivity. Histological examination of biopsies taken after photosensitizer injection and light exposure showed extensive changes in epidermis and dermis, including epidermal erosion, degranulation of the stratum granulosum, spongiosis, depletion in cellularity and mast cell degranulation. These changes were noted to be similar to changes caused by Photofrin.