| 61. |
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| 62. |
- Aebersold, M. A., et al.
(författare)
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Spin density maps in the triplet ground state of Cu-2(t-Bupy)(4)(N-3)(2) (ClO4)(2) (t-bupy = p-tert-butylpyridine): A polarized neutron diffraction study
- 1998
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Ingår i: Journal of the American Chemical Society. ; 120:21, s. 5238-5245
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Tidskriftsartikel (refereegranskat)abstract
- This paper is devoted to the determination of the spin distribution in the spin triplet ground state of [Cu-2(t-Bupy)(4)(N-3)(2)](ClO4)(2), With t-Bupy = p-tert-butylpyridine. The crystal structure, previously solved at room temperature from X-ray diffraction, has been redetermined at 18 K from unpolarized neutron diffraction. The structure consists of binuclear cations in which Cu2+ ions are doubly bridged by azido groups in the 1,1-fashion, and noncoordinated perchlorate anions. The experimental spin distribution has been determined from polarized neutron diffraction (PND) at 1.6 K under 50 kOe. The spin populations have been found to be strongly positive on the Cu2+ ions, weakly positive on the terminal and bridging nitrogen atoms of the azido groups as well as on the nitrogen atoms of the t-Bupy ligands, and weakly negative on the central nitrogen atoms of the N-3(-) bridges. The PND results have been discussed. The spin distribution in [Cu-2(t-Bupy)(4)(N-3)2](ClO4)(2) has been analyzed as resulting from a spin delocalization from the Cu2+ ions toward the azido bridges, to which a spin polarization effect within the azido pi orbitals is superimposed. The experimental data have been compared to the results of DFT calculations. The spin density map is qualitatively reproduced; however, the DFT calculations overestimate the spin delocalization from the Cu2+ ions toward the peripheral and bridging ligands.
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| 63. |
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| 64. |
- af Klinteberg, C, et al.
(författare)
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Laser-induced fluorescence diagnostics of basal cell carcinomas of the skin following topical ALA application
- 1996
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Ingår i: Optical Biopsies and Microscopic Techniques, Proceedings of. - : SPIE. - 0819423289 ; 2926, s. 32-40
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Konferensbidrag (refereegranskat)abstract
- Fourteen patients with superficial basal cell carcinomas (BCCs) and fifteen patients with nodular BCCs were investigated by means of laser-induced fluorescence (LIF) in connection with photodynamic therapy (PDT). Topical application of delta-amino levulinic acid (ALA) was performed six hours prior to the treatment session. Fluorescence spectra were recorded, using a point-monitoring system with an excitation wavelength of 405 nm. The measurements were performed in scans over the lesion and the surrounding normal skin before application of ALA, and immediately before and after the laser treatment. The selective uptake of the photosensitiser resulted in a fluorescence intensity ratio of 2.4:1 for superficial BCCs and 2.5:1 for nodular BCCs. If the fluorescence intensity was divided by the autofluorescence, this resulted in a contrast enhancement of about a factor 6 for tumour tissue. In seven patients (five with nodular BCC and two with superficial BCC), additional fluorescence measurements were performed two and four hours following the ALA application, and two hours after the PDT procedure. Thus, the kinetics of the transformation of ACA to protoporphyrin IX (PpIX) could be followed, which indicated that the synthesis of PpIX was more rapid in the tumour than in the normal tissue. After four hours, the PpIX level inside the tumour was saturated, while there still was an accumulation in the surrounding skin. The highest contrast between tumour and normal skin was reached within two hours after the ALA application.
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| 65. |
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| 66. |
- Afshari, Alireza, 1956
(författare)
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Determination of VOC Emissions from Surface Coatings by Environmental Test Chamber Measurements
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The emitting properties of different building materials are obtained by measurements in environmental chambers of a few established designs. In order to interpret the results from the measurements and to predict the influence on the indoor environment, it is necessary to have a good understanding of the parameters governing the emission process. The aim of this thesis is to contribute to this understanding by focusing on the process of emission of chemicals from building materials and on the influence of a number of parameters governing the process. In emission studies reported in the literature, few investigations deal with the comparison of the VOC emission rates obtained by measurements in different test chambers. In the present study, a 1m3-chamber, a CLIMPAQ and a FLEC were used for measurement of the concentrations of various compounds from surface coatings. The study focuses on parameters which could be considered to have a substantial influence on the emission rates, or which do not appear to have been thoroughly studied previously. Interest has mainly been focused on the influence of air velocity, airflow rate and sorption on the emission rate, when other parameters have been maintained constant. It was found that during the first 24 hours, by varying the airflow rate under given test conditions in a test chamber, a number of physical parameters have a direct influence on the emission process. From the start of the test until steady state has been reached, the measured concentration variations may be divided into three different phases. The results from measurements showed that the higher the airflow rates, the faster a steady state was attained. Furthermore, all the selected substances did not reach steady state at the same time during the experiments. The effect of the air velocity above the surface on the emission of VOCs was studied in the three mentioned environmental chambers. It was found that the emission rates of the compounds at 22, 23 and 24 hours after the start of the test systematically increase with increasing air velocity. It was possible to determine the magnitude of increase to 10-20%. However, it was difficult to determine the exact level of increase of the emission rate, due to the uncertainty of the measurements and the low levels of increase. Finally, the characterisation of adsorption of VOCs on the inside of the empty chambers has been studied. The experimental studies for all three chambers show that the sorption of substances in the 1 m3-chamber was slightly lower than in the FLEC. The CLIMPAQ shows a larger capacity of sorption with material specimens than without material specimens. This indicates that the gases emitted from painted plates adsorb again onto the test materials.
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| 67. |
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| 68. |
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| 69. |
- Agneholm, Evert, 1968
(författare)
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Cold Load Pick-up
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The load behaviour of the industrial and residential sector following different types of outages is dealt with in this dissertation. Data on the power consumption after these outages have been used for deriving models of the cold load pick-up. In the industrial sector the investigation covers a variety of branches and special attention has been given to plants having a high degree of electric energy consumption. Data of the power consumption after planned and forced outages have been collected and descriptions over typical restarting procedures and common restoration problems have been summarized. Due to the fact that the production can not start immediately after voltage is restored, the power consumption from the industrial sector will be lower after an outage as compared with the pre disturbance condition. The time it takes to enter a normal production again varies considerably and may take minutes or up to days for sensitive processing industries. When studying the residential sector, individual load objects, individual houses and residential areas have been investigated by laboratory and field measurements. The reason for this is to get a better understanding of how different load objects and electric heating behave after an outage. This knowledge is then used when analysing measurements of the cold load pick-up in residential areas. The measurements clearly indicate that the cold load pick-up for residential load has the opposite behaviour as compared with industrial load which means that it is (much) higher after an outage and then decreases to its normal level after a time. As residential load often is used in schemes of rotating load curtailment, simulations of such a scheme have been performed. The results show that it is important to tune this scheme properly in order to achieve the desired operation.
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| 70. |
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