| 1. |
- Ding, HT, et al.
(författare)
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Parallel cloning, expression, purification and crystallization of human proteins for structural genomics
- 2002
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Ingår i: Acta Crystallographica. Section D: Biological Crystallography. - 1399-0047. ; 58, s. 2102-2108
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Tidskriftsartikel (refereegranskat)abstract
- 54 human genes were selected as test targets for parallel cloning, expression, purification and crystallization. Proteins from these genes were selected to have a molecular weight of between 14 and 50 kDa, not to have a high percentage of hydrophobic residues (i.e. more likely to be soluble) and to have no known crystal structures and were not known to be subunits of heterocomplexes. Four proteins containing transmembrane regions were selected for comparative tests. To date, 44 expression clones have been constructed with the Gateway(TM) cloning system (Invitrogen, The Netherlands). Of these, 35 clones were expressed as recombinant proteins in Escherichia coli strain BL21 (DE3)-pLysS, of which 12 were soluble and four have been purified to homogeneity. Crystallization conditions were screened for the purified proteins in 96-well plates under oil. After further refinement with the same device or by the hanging-drop method, crystals were grown, with needle, plate and prism shapes. A 2.12 Angstrom data set was collected for protein NCC27. The results provide insights into the high-throughput target selection, cloning, expression and crystallization of human genomic proteins.
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| 2. |
- Zhang, J. G., et al.
(författare)
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Microstructure and mechanical properties of spray formed ultrahigh-carbon steels
- 2004
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Ingår i: Materials Science & Engineering. - : Elsevier BV. - 0921-5093 .- 1873-4936. ; 383:1, s. 45-49
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Tidskriftsartikel (refereegranskat)abstract
- The microstructure and mechanical properties of the spray formed 1.25C-3.0Si-1.5Cr ultrahigh-carbon steel (UHCS) were described. The 1.25C-3.0Si-1.5Cr UHCS was processed by spray forming to break up carbide networks. The fine pearlites with average interlamellar spacing of 0.20 mum was observed in the as-sprayed microstructure. The ultimate tensile strength and the pearlite spacing can be related by the Hall-Petch equation. The as-sprayed 1.25C-3.0Si-1.5Cr UHCS consisting of fine lamellar pearlites has been shown to exhibit superplastic behavior at elevated temperature. The dramatic change of microstructure from fine lamellar pearlites to equiaxed grains stabilized by spheroidized particles during superplastic deformation has been observed. The estimation on the basis of thermodynamics shows that the content of chromium of 1.54 wt.% is needed to inhibit graphite formation in the l.25C-3.OSi-1.5Cr UHCS.
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| 3. |
- Zhu, Bin, et al.
(författare)
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Transparent two-phase composite oxide thin films with high conductivity
- 2001
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Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 385:02-jan, s. 209-214
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Tidskriftsartikel (refereegranskat)abstract
- New types of transparent thin films based on CeO2-Al2O3 and -SiO2 and ion-doped CeO2 composite oxides have been developed by sol-gel process. The films have two phases: a host phase, CeO2 or ion-doped CeO2; and a guest phase Al2O3 or SiO2, so called binary composites. This is the unique character to distinguish from other transparent films, e.g. CeO2-SnO2, -TiO2 and -ZrO2 single phase (solid solution), for electrochromic applications. Film conductivity was determined by impedance analysis and electrochemical property was investigated by cyclic voltammetry. The conductivity of the composite films is in the range of 10(-2)-0.2 S/cm in the temperature range of 500-700 degreesC. Binary films containing 30% alumina and 50% silica with thickness 35 and 30 nm have the highest amount of charge exchange for 1.0 Li/Ce and 0.7 Li/Ce, respectively. After 380 cycles the charge capacity of the CeO2-Al2O3 reached about the same value as started in the beginning. The films show a high transmittance for visible light. Unusual properties for these composite thin films have been implemented due to the special thin film nano-structure and two-phase regions and interfaces, The ionic transport and insertion/extraction mechanisms in these new composite film materials are discussed based on a proposed physical model. These composite films have a broad application in various electrochemical devices, such as electrochromic and fuel cell devices.
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| 4. |
- Carniato, S., et al.
(författare)
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Ab initio study of the Cu 2p and 3s core-level XPS spectra of copper phthalocyanine
- 2002
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 66:4
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Tidskriftsartikel (refereegranskat)abstract
- The x-ray photoelectron spectra (XPS) of copper tetraazaporphyrin (CuTAP), used as a model of copper phthalocyanine(CuPc) are studied by theoretical simulations. The nature of the main and satellite features observed in the XPS Cu 2p and Cu 3s photoelectron spectra are discussed based on the results of the charge-transfer (CT) model and of ab initio calculations in the sudden approximation limit. It is shown that the two descriptions of the core level final states can be derived from the two types of approaches. The final-state wave functions given by the CT model are described in a shakedown scenario. This process produces a well-screened final 2p(5)3d(10)(L) under bar configuration ((L) under bar denotes a ligand hole) on the Cu atom together with the core hole, resulting in the main spectral peak. On the other hand, the process where the outer electron stays on the ligand corresponds to the satellite with a poorly-screened 2p(5)3d(9) character. The ab initio calculations, performed on an isolated copper tetraazaporphyrin molecule at the Hartree-Fock (HF) level, the multi-configuration self-consistent field level, and the hybrid density-functional-theory levels show that the core hole final states (satellite/main peak) can be attributed to valence-valence transitions. We show that a correct intensity distribution of the different features, including the so-called white line and the satellite structures, can be obtained when the electronic relaxation and correlation and the overlap between the ground-state and final-state Slater determinants are explicitly taken into account. It is found that the nature of the main peak is strongly depending on the Ligand-to-Metal charge transfer, on the exchange interaction and on the core-hole-3d-hole interaction energies.
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| 5. |
- Lundberg, G, et al.
(författare)
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A rat model for severe limb ischemia at rest
- 2003
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Ingår i: European surgical research. Europaische chirurgische Forschung. Recherches chirurgicales europeennes. - : S. Karger AG. - 0014-312X. ; 35:5, s. 430-438
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Tidskriftsartikel (refereegranskat)abstract
- We sought an animal model able to discriminate metabolic and angiogenic processes in limb ischemia. For that we modified and evaluated a rat model of severe unilateral limb ischemia at rest. A two-stage surgical procedure entailing left femoral artery ligation preceded by interruption of collateral vessels originating from the infra-renal aorta and left iliac arteries was performed in Sprague-Dawley rats. The model was evaluated for up to 8 weeks with a transit-time flow meter, a laser Doppler perfusion imager, microspheres, arteriography and histology. It was found to be well tolerated with low mortality and perfusion in the foot skin was reduced up to 8 weeks, while collaterals were visible after 2 weeks. Histologic signs of ischemia were seen for up to 4 weeks. This rat model of severe limb ischemia at rest lasts up to 8 weeks and seems well suited for longitudinal studies of the pathophysiology of limb ischemia and healing mechanisms like angio- and arteriogenesis.
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| 6. |
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| 7. |
- Luo, X, et al.
(författare)
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RFI suppression in ultra-wideband SAR systems using LMS filters in frequency domain
- 2001
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Ingår i: Electronics Letters. - 0013-5194 .- 1350-911X. ; 37:4, s. 241-243
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Tidskriftsartikel (refereegranskat)abstract
- A least-mean-square algorithm in the frequency domain, with amplitude normalisation. is proposed to remove narrowband radio frequency interference in low-frequency ultra-wideband synthetic aperture radar systems. The performance uf the algorithm was tested on experimental data acquired with the CARABAS system.
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| 8. |
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| 9. |
- Myneni, S., et al.
(författare)
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Spectroscopic probing of local hydrogen-bonding structures in liquid water
- 2002
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Ingår i: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 14:8, s. L213-L219
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the electronic structure of liquid water using x-ray absorption spectroscopy at the oxygen K edge. Since the x-ray absorption process takes less than a femtosecond, it allows probing of the molecular orbital structure of frozen, local geometries of water molecules at a timescale that has not previously been accessible. Our results indicate that the electronic structure of liquid water is significantly different from that of the solid and gaseous forms, resulting in a pronounced pre-edge feature below the main absorption edge in the spectrum. Theoretical calculations of these spectra suggest that this feature originates from specific configurations of water, for which the H-bond is broken on the H-donating site of the water molecule. This study provides a fingerprint for identifying broken donating H-bonds in the liquid and shows that an unsaturated H-bonding environment exists for a dominating fraction of the water molecules.
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| 10. |
- Pettersson, L. G. M., et al.
(författare)
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Electronic structure effects from hydrogen bonding in the liquid phase and in chemisorption : an integrated theory and experimental effort
- 2001
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Ingår i: Journal of Synchrotron Radiation. - 0909-0495 .- 1600-5775. ; 8, s. 136-140
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Tidskriftsartikel (refereegranskat)abstract
- A closely integrated theoretical and experimental effort to understand chemical bonding using X-ray spectroscopic probes is presented. Theoretical techniques to simulate XAS (X-ray absorption spectroscopy), XES (X-ray emission spectroscopy), RIXS (resonant inelastic X-ray scattering) and XPS (X-ray photoelectron spectroscopy) spectra have been developed and implemented within a density functional theory (DFT) framework. In combination with new experimental techniques, such as high-resolution XAS on liquid water under ambient conditions and XES on complicated surface adsorbates, new insight into e.g. hydrogen-bonded systems is obtained. For the (3 x 2) overlayer structure of glycine/Cu(110), earlier work has been extended to include adsorbate-adsorbate interactions. Structures are optimized for large cluster models and for periodic boundary conditions. It is found that specific features in the spectra arise from hydrogen-bonding interactions, which thus have important effects at the molecular-orbital level. XAS on liquid water shows a pronounced pre-edge feature with significant intensity, while the spectrum of ice shows only little intensity in this region. Theoretical spectrum calculations, based on instantaneous structures obtained from molecular-dynamics (MD) simulations, show that the pre-edge feature in the liquid is caused by water molecules with unsaturated hydrogen bonding. Some aspects of the theoretical simulations will be briefly discussed.
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| 11. |
- Triguero, L., et al.
(författare)
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Direct experimental measurement of donation/back-donation in unsaturated hydrocarbon bonding to metals
- 2000
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 122:49, s. 12310-12316
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Tidskriftsartikel (refereegranskat)abstract
- Using resonant and off-resonant X-ray emission spectroscopy, in combination with ground-state density functional calculations, we examine the electronic structure of chemisarbed ethylene and benzene on thr Cu(110) surface to investigate the suitability of the donation/back-donation bonding model given by Dewar(1) and Chart and Duncanson(2) (DCD) for the interaction of unsaturated hydrocarbons with metal surfaces. We give an experimental verification of the DCD model and find donation/back-donation to be twice as large for ethylene as for benzene. In particular, the degree of sigma-pi mixing (rehybridization) is found to correspond to the amount of donation/back-donation, which is put in relation to the aromatic and nonaromatic pi characters of benzene and ethylene, respectively.
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| 12. |
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| 13. |
- Ye, Q, et al.
(författare)
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Prospective study of relationship between cytomegalovirus pneumonia and viral load in renal transplant recipients
- 2004
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Ingår i: Transplantation Proceedings. - : Elsevier BV. - 0041-1345. ; 36:10, s. 3036-3041
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Tidskriftsartikel (refereegranskat)abstract
- The present study prospectively examined the relationship between cytomegalovirus interstitial pneumonia (CMV-IP) and viral load among 56 renal transplant recipients. We sought to identify the cutoff of viral load to predict CMV-IP. Blood samples were obtained weekly within the first 2 months and every second week during 2 to 6 months after kidney transplantations. A commercial real-time polymerase chain reaction (PCR)-method was applied to quantify CMV-DNA in plasma or in leukocytes. Among 54 renal transplant recipients who were analyzed for CMV-DNA in the blood (96.4%), 8 experienced CMV-IP (14.3%) and 2 died (3.6%). After kidney transplantation, CMV-DNA loads were near 0 in plasma before the week 4 and before the week 3 in leukocytes among both groups. From week 5 (week 4, in leukocytes), plasma CMV-DNA loads in the CMV-IP group increased, the peak value reached at week 8 in plasma and the week 9 in leukocytes. Whereas, the CMV-DNA loads both in plasma and in leukocytes in the non-CMV-IP group fluctuated at lower levels, those in plasma were significantly different between the 2 groups at the weeks 5, 7, and 9. For CMV-DNA in leukocytes, there were significant differences between 2 groups from week 6 to week 11. The present study demonstrated that dynamic determination of CMV-DNA may predict the occurrence of CMV-IP. Viral loads over 10(4) copies/mL plasma continuing for 3 weeks may serve as a cutoff to predict CMV-IP.
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| 14. |
- Zhu, B, et al.
(författare)
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Transparent two-phase composite oxide thin films with high conductivity
- 2001
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Ingår i: THIN SOLID FILMS. - : ELSEVIER SCIENCE SA. - 0040-6090. ; 385:1-2, s. 209-214
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Tidskriftsartikel (refereegranskat)abstract
- New types of transparent thin films based on CeO2-Al2O3 and -SiO2 and ion-doped CeO2 composite oxides have been developed by sol-gel process. The films have two phases: a host phase, CeO2 or ion-doped CeO2; and a guest phase Al2O3 or SiO2, so called binar
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