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- Dunham, I, et al.
(författare)
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The DNA sequence of human chromosome 22
- 1999
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 402:6761, s. 489-495
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Tidskriftsartikel (refereegranskat)
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| 2. |
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| 4. |
- Zhang, Yuan, et al.
(författare)
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Pituitary adenylate cyclase activating peptide expression in the rat dorsal root ganglia : up-regulation after peripheral nerve injury
- 1996
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Ingår i: Neuroscience. - : Elsevier BV. - 0306-4522. ; 74:4, s. 110-1099
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Tidskriftsartikel (refereegranskat)abstract
- Pituitary adenylate cyclase activating peptide (PACAP) is expressed in a population of capsaicin-sensitive primary sensory neurons of small to medium size in the rat. In the present report we have examined the effect of sciatic nerve injury (unilateral transection) on PACAP expression (immunocytochemistry, radioimmunoassay, in situ hybridization and northern blot analysis) in dorsal root ganglia at the lumbar level and on immunoreactive PACAP in the spinal cord and in the sciatic nerve stump. For comparison, calcitonin gene-related peptide was examined. In dorsal root ganglia of the intact side immunoreactive PACAP and PACAP messenger RNA were localised to a population of nerve cell bodies of small to medium size. In dorsal root ganglia on the injured side, PACAP-immunoreactive nerve cell bodies were more numerous and PACAP messenger RNA was considerably more abundant as studied 14 days after sciatic nerve transection. By contrast, calcitonin gene-related peptide-containing nerve cell bodies were numerous and rich in calcitonin gene-related peptide messenger RNA in dorsal root ganglia on the intact side, while after transection both the number of immunoreactive nerve cell bodies and their content of messenger RNA were markedly reduced. There were indications of axotomy-induced expression of PACAP messenger RNA in larger neurons. In the dorsal horn of the spinal cord on the intact side PACAP and calcitonin gene-related peptide-immunoreactive fibres were densely accumulated in the superficial layers. On the transected side the densities of both PACAP and calcitonin gene-related peptide-immunoreactive nerve fibres were reduced in the medial part. The data obtained indicate a marked up-regulation of PACAP in sensory neurons following peripheral nerve injury. Since PACAP depresses a C-fibre evoked flexion reflex, this may have implications for sensory transmission. Further, in view of the known promoting effects of PACAP on neuronal survival and differentiation and non-neuronal cell growth as well as its proinflammatory effects a role of PACAP in the neuronal and periaxonal tissue restoration after injury is not inconceivable.
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| 8. |
- Zhang, L, et al.
(författare)
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Biodegradability of regenerated cellulose films coated with polyurethane/natural polymers interpenetrating polymer networks
- 1999
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Ingår i: Industrial & Engineering Chemistry Research. - : American Chemical Society (ACS). - 0888-5885 .- 1520-5045. ; 38:11, s. 4284-4289
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Tidskriftsartikel (refereegranskat)abstract
- Interpenetrating polymer network (IPN) coatings synthesized from castor- oil-based polyurethane (PU) with chitosan, nitrocellulose, or elaeostearin were coated on regenerated cellulose (RC) film for curing at 80-100 °C for 2-5 min, providing biodegradable, water-resistant cellulose films coded, respectively, as RCCH, RCNC, and RCEs. The coated films were buried in natural soil for decaying and inoculated with a spore suspension of fungi on the agar medium, respectively, to test biodegradability. The viscosity- average molecular weight, M(n), and the weight of the degraded films decreased sharply with the progress of degradation. The degradation half- lifes, t(1/2), of the films in soil at 30 °C were found to be 19 days for RC, 25 days for RCNC, 32 days for RCCH, and 45 days for the RCEs films. Scanning electron microscopy (SEM) showed that the extent of decay followed in the order RC > RCNC > RCCH > RCEs. SEM, infrared (IR), high-performance liquid chromatography (HPLC), and CO2 evolution results indicated that the microorganisms directly attacked the water-resistant coating layer and then penetrated into the cellulose to speedily metabolize, while accompanying with producing CO2, H2O, glucose cleaved from cellulose, and small molecules decomposed from the coatings.Interpenetrating polymer network (IPN) coatings synthesized from castor-oil-based polyurethane (PU) with chitosan, nitrocellulose, or elaeostearin were coated on regenerated cellulose (RC) film for curing at 80-100°C for 2-5 min, providing biodegradable, water-resistant cellulose films coded, respectively, as RCCH, RCNC, and RCEs. The coated films were buried in natural soil for decaying and inoculated with a spore suspension of fungi on the agar medium, respectively, to test biodegradability. The viscosity-average molecular weight, Mη, and the weight of the degraded films decreased sharply with the process of degradation. The degradation half-lifes, t1/2, of the films in soil at 30°C were found to be 19 days for RC, 25 days for RCNC, 32 days for RCCH, and 45 days for the RCEs films. Scanning electron microscopy (SEM) showed that the extent of decay followed in the order RC > RCNC > RCCH > RCEs. SEM, infrared (IR), high-performance liquid chromatography (HPLC), and CO2 evolution results indicated that the microorganisms directly attacked the water-resistant coating layer and then penetrated into the cellulose to speedily metabolize, while accompanying with producing CO2, H2O, glucose cleaved from cellulose, and small molecules decomposed from the coatings.
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| 10. |
- Zhang, Z. X., et al.
(författare)
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Effects of loading rate on rock fracture
- 1999
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Ingår i: International Journal of Rock Mechanics And Mining Sciences. - 1365-1609 .- 1873-4545. ; 36:5, s. 597-611
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Tidskriftsartikel (refereegranskat)abstract
- By means of a wedge loading applied to a short-rod rock fracture specimen tested with the MTS 810 or SHPB (split Hopkinson pressure bar), the fracture toughness of Fangshan gabbro and Fangshan marble was measured over a wide range of loading rates, =10−2–106 MPa m1/2 s−1. In order to determine the dynamic fracture toughness of the rock as exactly as possible, the dynamic Moiré method and strain–gauge method were used in determining the critical time of dynamic fracture. The testing results indicated that the critical time was generally shorter than the transmitted wave peak time, and the differences between the two times had a weak increasing tendency with loading rates. The experimental results for rock fracture showed that the static fracture toughness KIc of the rock was nearly a constant, but the dynamic fracture toughness KId of the rock (≥104 MPa m1/2 s−1) increased with the loading rate, i.e. log(KId)=a log +b. Macroobservations for fractured rock specimens indicated that, in the section (which was perpendicular to the fracture surface) of a specimen loaded by a dynamic load, there was clear crack branching or bifurcation, and the higher the loading rate was, the more branching cracks occurred. Furthermore, at very high loading rates (≥106 MPa m1/2 s−1) the rock specimen was broken into several fragments rather than only two halves. However, for a statically fractured specimen there was hardly any crack branching. Finally, some applications of this investigation in engineering practice are discussed.
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