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51.
Björn Gustafsson Mihai Putinar 《Journal of Mathematical Analysis and Applications》2007,328(2):995-1006
The analytic continuation of the exponential transform of a domain in Rn is proved under some global geometric assumptions on the boundary. Two approximation schemes of the continued transform (one based on a Taylor series truncation, the other on a global eigenfunction expansion) are also discussed. 相似文献
52.
In this study a comparison between GaP layers, grown by metalorganic vapour phase epitaxy on either (111) oriented GaP substrates or (001) oriented GaP substrates, is made with respect to the near-band-edge luminescence. Spectrally resolved cathodoluminescence, CL, images were recorded at ˜ 25 K with detection on either the bound exciton emission or the donor-to-acceptor pair emission. The intensity variations observed in the CL images are interpreted in terms of aggregation of impurities around threading dislocations. Contrary to the layers grown on (001) oriented substrates, the layers grown on (111) oriented substrates show a segregation effect of the acceptor constituent involved in the donor-to-acceptor pair emission. 相似文献
53.
R. Albrecht T. C. Awes P. Beckmann F. Berger M. A. Bloomer D. Bock R. Bock G. Claesson G. Clewing L. Dragon A. Eklund R. L. Ferguson A. Franz S. Garpman R. Glasow H. Å. Gustafsson H. H. Gutbrod M. Hartig G. Hölker J. Idh P. Jacobs K. H. Kampert B. W. Kolb P. Kristiansson H. Löhner I. Lund F. E. Obenshain A. Oskarsson I. Otterlund T. Peitzmann S. Persson F. Plasil A. M. Poskanzer M. Purschke H. G. Ritter B. Roters S. Saini R. Santo H. R. Schmidt R. Schmidt S. P. Sørensen K. Steffens P. Steinhauser E. Stenlund D. Stüken M. L. Tincknell A. Twyhues G. R. Young 《Zeitschrift fur Physik C Particles and Fields》1992,53(2):225-237
Correlations between positive pions are investigated in the target fragmentation region of 200A GeV16O+nucleus collisions. The pions are measured with the Plastic Ball detector in the WA80 experiment at the CERN SPS. The target mass dependence of the radii and the correlation strength extracted by interferometry is studied. A new approach to the fit of the correlation function is introduced. The correlation strength and both invariant and transverse radii increase with decreasing target mass. The transverse radius for16O+C reactions appears to be much larger than the geometrical radius of the nuclei involved. For the Au target only a small fraction of the measured pions contributes to the apparent correlation. Hints for a much larger second component in16O+Au reactions are observed. Rescattering phenomena may provide a clue to understand these phenomena. 相似文献
54.
55.
Prof. Dr. Ivo Leito Prof. Dr. Ilmar A. Koppel Dr. Ivar Koppel Dr. Karl Kaupmees Sofja Tshepelevitsh Jaan Saame 《Angewandte Chemie (International ed. in English)》2015,54(32):9262-9265
The potential limits of superbasicity achievable with different families of neutral bases by expanding the molecular framework are explored using DFT computations. A number of different core structures of non‐ionic organosuperbases are considered (such as phosphazenes, guanidinophosphazenes, guanidino phosphorus ylides). A simple model for describing the dependence of basicity on the extent of the molecular framework is proposed, validated, and used for quantitatively predicting the ultimate basicities of different compound families and the rates of substituent effect saturation. Some of the considered bases (guanidino phosphorus carbenes) are expected to reach gas‐phase basicity around 370 kcal mol?1, thus being the most basic neutral bases ever reported. Also, the classical substituted alkylphosphazenes were predicted to reach pKa values of around 50 in acetonitrile, which is significantly higher than previously expected. 相似文献
56.
Torbjörn Pettersson Johannes Hellwig Per-Johan Gustafsson Stig Stenström 《Cellulose (London, England)》2017,24(10):4139-4149
Flexibility and modulus of elasticity data for two types of wet cellulose fibres using a direct force–displacement method by means of AFM are reported for never dried wet fibres immersed in water. The flexibilities for the bleached softwood kraft pulp (BSW) fibres are in the range of 4–38 × 1012 N?1 m?2 while the flexibilities for the thermomechanical pulp (TMP) fibres are about one order of magnitude lower. For BSW the modulus of elasticity ranges from 1 to 12 MPa and for TMP between 15–190 MPa. These data are lower than most other available pulp fibre data and comparable to a soft rubber band. Reasons for the difference can be that our measurements with a direct method were performed using never dried fibres immersed in water while other groups have employed indirect methods using pulp with different treatments. 相似文献
57.
Tommy Gustafsson 《Archive for Rational Mechanics and Analysis》1986,92(1):23-57
This paper studies Lp-estimates for solutions of the nonlinear, spatially homogeneous Boltzmann equation. The molecular forces considered include inverse kth-power forces with k > 5 and angular cut-off.The main conclusions are the following. Let f be the unique solution of the Boltzmann equation with f(v,t)(1 + ¦v2¦)(s
1
+ /p)/2 L1, when the initial value f
0 satisfies f
0(v) 0, f
0(v) (1 + ¦v¦2)(s
1
+ /p)/2 L1, for some s1 2 + /p, and f
0(v) (1 + ¦v¦2)s/2 Lp. If s 2/p and 1 < p < , then f(v, t)(1 + ¦v¦2)(s s
1)/2 Lp, t > 0. If s >2 and 3/(1+ ) < p < , thenf(v,t) (1 + ¦v¦2)(s(s
1
+ 3/p))/2 Lp, t > 0. If s >2 + 2C0/C1 and 3/(l + ) < p < , then f(v,t)(1 + ¦v¦2)s/2 Lp, t > 0. Here 1/p + 1/p = 1, x y = min (x, y), and C0, C1, 0 < 1, are positive constants related to the molecular forces under consideration; = (k – 5)/ (k – 1) for kth-power forces.Some weaker conclusions follow when 1 < p 3/ (1 + ).In the proofs some previously known L-estimates are extended. The results for Lp, 1 < p < , are based on these L-estimates coupled with nonlinear interpolation. 相似文献
58.
Nils Carlsson Hanna Gustafsson Christian Thörn Lisbeth Olsson Krister Holmberg Björn Åkerman 《Advances in colloid and interface science》2014
Mesoporous materials as support for immobilized enzymes have been explored extensively during the last two decades, primarily not only for biocatalysis applications, but also for biosensing, biofuels and enzyme-controlled drug delivery. The activity of the immobilized enzymes inside the pores is often different compared to that of the free enzymes, and an important challenge is to understand how the immobilization affects the enzymes in order to design immobilization conditions that lead to optimal enzyme activity. This review summarizes methods that can be used to understand how material properties can be linked to changes in enzyme activity. Real-time monitoring of the immobilization process and techniques that demonstrate that the enzymes are located inside the pores is discussed by contrasting them to the common practice of indirectly measuring the depletion of the protein concentration or enzyme activity in the surrounding bulk phase. We propose that pore filling (pore volume fraction occupied by proteins) is the best standard for comparing the amount of immobilized enzymes at the molecular level, and present equations to calculate pore filling from the more commonly reported immobilized mass. Methods to detect changes in enzyme structure upon immobilization and to study the microenvironment inside the pores are discussed in detail. Combining the knowledge generated from these methodologies should aid in rationally designing biocatalyst based on enzymes immobilized in mesoporous materials. 相似文献
59.
60.
B Egestad P Pettersson J Sj?vall J Rafter K Hyv?nen J A Gustafsson 《Biomedical chromatography : BMC》1987,2(3):120-134
Rats, germfree and conventional, were dosed with 14C-labelled benzo[a]pyrene. Faeces and urine were collected. Metabolites in faeces were effectively extracted with a new method using a combination of solvents and solid sorbents. Metabolites in urine were extracted with octadecylsilane-bonded silica. The metabolites were fractionated into groups by chromatography on a cation exchanger (SP-LH-20 or SP-Sephadex C-25) and an anion exchanger (TEAP-LH-20). Some of the groups were further purified by column chromatography and analysed by HPLC and TLC. The analyses show a complex pattern of metabolism. A large part of the metabolites (9-24% depending on animal type and route of excretion) had amphoteric properties, e.g. like glutathione and cysteine conjugates. The abundance of conjugates sensitive to beta-glucuronidase and sulphatase was low. The relative amount of acidic conjugates in faeces was much higher in the germfree than in the conventional rats indicating the influence of the intestinal flora on the metabolism. The results support the view that the mercapturic acid pathway is a quantitatively important metabolic route for benzo[a]pyrene in rats. The methods of extraction and group fractionation were designed to be generally applicable to the analysis of lipophilic xenobiotics and their metabolites. 相似文献