| 1. |
- Dutta, D, et al.
(författare)
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Nuclear transparency with the gamma n ->pi(-)p process in He-4
- 2003
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 68:2: 021001
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Tidskriftsartikel (refereegranskat)abstract
- We have measured the nuclear transparency of the fundamental process gamman-->pi(-)p in He-4. These measurements were performed at Jefferson Lab in the photon energy range of 1.6-4.5 GeV and at theta(cm)(pi)=70degrees and 90degrees. These measurements are the first of their kind in the study of nuclear transparency in photoreactions. They also provide a benchmark test of Glauber calculations based on traditional models of nuclear physics. The transparency results suggest deviations from the traditional nuclear physics picture. The momentum transfer dependence of the measured nuclear transparency is consistent with Glauber calculations that include the quantum chromodynamics phenomenon of color transparency.
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| 2. |
- Zhu, LY, et al.
(författare)
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Cross-section measurement of charged-pion photoproduction from hydrogen and deuterium
- 2003
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Ingår i: Physical Review Letters. - 1079-7114. ; 91:2: 022003
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Tidskriftsartikel (refereegranskat)abstract
- We have measured the differential cross section for the gamman-->pi(-)p and gammap-->pi(+)n reactions at theta(c.m.)=90degrees in the photon energy range from 1.1 to 5.5 GeV at Jefferson Lab (JLab). The data at E(gamma)greater than or similar to3.3 GeV exhibit a global scaling behavior for both pi(-) and pi(+) photoproduction, consistent with the constituent counting rule and the existing pi(+) photoproduction data. Possible oscillations around the scaling value are suggested by these new data. The data show enhancement in the scaled cross section at a center-of-mass energy near 2.2 GeV. The cross section ratio of exclusive pi(-) to pi(+) photoproduction at high energy is consistent with the prediction based on one-hard-gluon-exchange diagrams.
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| 3. |
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| 4. |
- Zeng, J, et al.
(författare)
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Expression of zinc-positive cells and terminals in fetal neocortical homografts to adult rat depends on lesion type and rearing conditions
- 2000
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Ingår i: Experimental Neurology. - : Elsevier BV. - 0014-4886. ; 164:1, s. 176-183
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Tidskriftsartikel (refereegranskat)abstract
- Zinc-positive neurons and terminals, known to be associated with the glutamatergic projections in the brain, can be demonstrated by the histochemical Timm method and later modifications thereof. The adult rat neocortex contain a uniform lamination of zinc-positive cells with specific projections to, e.g., the striatum. We have previously reported that fetal neocortical grafts implanted in the adult rat neocortex combined with rearing in an enriched environment can improve behavioral functions and reduce the secondary atrophy of thalamus after cortex infarction in adult rats. In order to examine whether the expression of zinc positivity is ontogenetically inherent to neocortical neurons we grafted fetal neocortical tissue to aspiration or ischemic lesions of the frontoparietal neocortex of adult rats, followed by histochemical visualization of the vesicular zinc pool by selenite or sulfide. One further aim of the study was to elucidate to what extent the distribution of zinc-containing neurons and terminals in the grafts depended on rearing under different environmental conditions. The foremost finding of the present study was that the overall density of zinc-containing terminals in fetal cortical transplants placed in brain infarcts of adult spontaneously hypertensive rats is higher when the rats are reared in an enriched environment. Moreover, the presence and expression of zinc-positive neurons and terminals do not seem to be ontogenetically inherent to the cortical neurons as the fetal neocortical grafts placed in aspiration lesions contained no zinc-selenide-positive neurons and few or no zinc-selenide-positive terminals. The presence or expression of zinc-positive cells may thus be induced by ingrowth of fibers and terminals from the host brain as transplants placed in the ischemic lesions expressed both zinc-positive neurons and terminals.
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| 5. |
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| 6. |
- Zhang, L. N., et al.
(författare)
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Solution properties of antitumor sulfated derivative of alpha-(1 -> 3)-D-glucan from Ganoderma lucidum
- 2000
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Ingår i: Bioscience, biotechnology and biochemistry. - : Oxford University Press (OUP). - 0916-8451 .- 1347-6947. ; 64:10, s. 2172-2178
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Tidskriftsartikel (refereegranskat)abstract
- Four fractions of a water-insoluble alpha-(1-->3)-D-glucan GL extracted from fruiting bodies of Ganoderma lucidum were dissolved in 0.25 M LiCl/DMsO, and then reacted with sulfur trioxide-pyridine complex at 80 degreesC to synthesize a series of water-soluble sulfated derivatives S-GL. The degree of substitution of DS was measured by using IR infrared spectra, elemental analysis, and C-13 NMR to be 1.2-1.6 in the non-selective sulfation. Weight-average molecular weight M, and intrinsic viscosity [eta] of the sulfated derivatives S-GL were measured by multi-angle laser light scattering and viscometry. The M-w value (2.4 x 10(4)) of sulfated glucan S-GL-1 was much lower than that (44.5 x 10(4)) of original alpha-(1-->3)-D-glucan GL-1. The Mark-Houwink equation and average value of characteristic ratio C-infinity for the S-GL in 0.2 M NaCl aqueous solution at 25 degreesC were found to be: [eta] =1.32 x 10(-3) M-w(1.06) (cm(3) g(-1)) and 16, respectively, in the M-w range from 1.1 x 10(4) to 2.4 x 10(4). It indicated that the sulfated derivatives of the alpha-(1-->3)-D-glucan in the aqueous solution behave as an expanded chain, owing to intramolecular hydrogen bonding or interaction between charge groups. Interestingly, two sulfated derivatives synthesized from the alpha-(1-->3)-D-glucan and curdlan, a beta-(1-->3)-D-glucan, all had significant higher antitumor activity against Ehrlich ascites carcinoma (EAC) than the originals. The effect of expanded chains of the sulfated glucan in the aqueous solution on the improvement of the antitumor activity could not be negligible.
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