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| 3. |
- Marangolo, M, et al.
(author)
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Magnetism of the Fe/ZnSe(001) interface
- 2002
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In: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 88:21, s. 217202-
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Journal article (peer-reviewed)abstract
- The magnetism of epitaxial ultrathin films of Fe on ZnSe(001) has been investigated by x-ray magnetic circular dichroism down to the submonolayer regime. In contrast to other metallic ferromagnet/semiconductor interfaces, no reduction of the Fe magnetic moment was found at the Fe/ZnSe(001) interface. Furthermore, a significant enhancement of the Fe magnetic moment compared to the bulk value was observed for coverages up to one monolayer in agreement with theoretical predictions. We also demonstrate that the magnetic properties of the Fe/ZnSe(001) interface remain stable against thermal annealing up to 300 degrees C, a prerequisite for the future development of efficient spintronics devices.
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| 4. |
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| 5. |
- Gustavsson, Fredrik, et al.
(author)
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Magnetic moment and anisotropy at the Fe/ZnSe(001) interface studied by conversion electron Mössbauer spectroscopy
- 2002
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 66:2, s. 024405-
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Journal article (peer-reviewed)abstract
- The interface magnetic properties of Fe/ZnSe heterostructures grown on GaAs(001) by molecular-beam epitaxy have been investigated using conversion electron Mössbauer spectroscopy (CEMS) and macroscopic magnetic measurements. For Fe films thinner than 100 Å an in-plane 〈110〉 uniaxial magnetic anisotropy was found and the magnetization loops could successfully be described by the simple Stoner-Wohlfarth model, which implies that the magnetization reverses only by coherent rotation and jump processes. For the interface analysis, a 5-Å-thick layer of enriched 57Fe was deposited on the ZnSe surface and buried under 20 Å of natural Fe. In this way the 57Fe serves as a local probe of the interface magnetic environment in a bulklike Fe film since the CEMS technique is only sensitive to this isotope of Fe. An interface magnetic moment of 2.18 μB was found and, in relation to 2.2 μB for bulk bcc Fe, this precludes the presence of any interface reactions. Surprisingly, however, the direction of the interface magnetic moment turned out to be reoriented from the [110] direction by almost 30°, an effect that was assumed to arise from the distribution of unidirectional tetrahedral bonds present on the Zn c(2×2) reconstructed ZnSe surface.
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| 6. |
- Gustavsson, Fredrik, et al.
(author)
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Structural and transport properties of epitaxial Fe/ZnSe/FeCo magnetic tunnel junctions
- 2001
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 64:18, s. 184422-
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Journal article (peer-reviewed)abstract
- The use of a semiconductor barrier in heteroepitaxy with ferromagnetic metal electrodes describes a novel type of magnetic tunnel junctions. In this work, epitaxial Fe/ZnSe/FeCo magnetic tunnel junctions have been grown on ZnSe(001) buffered GaAs(001) substrates by molecular beam epitaxy. Alloying a small amount of Co with Fe in the base electrode provides a better seed epilayer for the growth of the ZnSe barrier compared to pure Fe as seen by transmission electron microscopy. Detailed characterization of the FeCo surface was performed by in situ scanning tunneling microscopy and revealed pyramid-shaped defects of up to 60 Å in height distributed on the FeCo surface. Transport measurements on microfabricated tunnel junctions yielded up to 16% magnetoresistance at 10 K and the effect is attributed to spin polarized tunneling across the semiconductor barrier in the energy range of the gap. The observed anomalous character of the magnetoresistance was attributed to conduction through the pyramidal defects in the base FeCo layer.
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| 8. |
- Ronco, Claudio, et al.
(author)
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Blood flow distribution in sorbent beds : analysis of a new sorbent device for hemoperfusion
- 2000
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In: International Journal of Artificial Organs. - 0391-3988 .- 1724-6040. ; 23:2, s. 125-130
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Journal article (peer-reviewed)abstract
- A new polymer-based sorbent cartridge has been recently developed for enhancing middle molecule removal during hemodialysis. The cartridge (Betasorb, Renaltech, New York, USA) has been designed to be placed in series with the dialyzer in the blood circuit. It is therefore important to evaluate the distribution of flow into the blood compartment of the device in order to assess if the surface of the sorbent is utilized to the best. For this purpose, a special imaging technique was utilized. Cartridges were analyzed during a simulated in vitro circulation at 250 and 350 ml/min of blood flow and 25% and 40% hematocrit. Cartridges were placed in vertical position and a cross longitudinal section 1 cm thick was analyzed in sequence by a helical scanner. Dye was injected into the arterial inlet and the progressive distribution was evaluated by sequential densitometrical measures carried out automatically by the machine. The sequential images analyzed by the scanner demonstrated excellent distribution of the flow in the blood compartment with minimal difference between the central and the peripheral regions of the compartment. In particular the following flow velocity pattern could be observed under the different experimental conditions tested. We may conclude that the cartridge design is adequate and no channelling effects could be detected in the blood compartment. The flow distribution is slightly affected by changes in flow rate and hematocrit showing an optimal utilization of the available surface for molecule adsorption.
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| 9. |
- van Kuilenburg, André B P, et al.
(author)
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Novel disease-causing mutations in the dihydropyrimidine dehydrogenase gene interpreted by analysis of the three-dimensional protein structure
- 2002
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In: Biochemical Journal. - : Portland Press Ltd.. - 0264-6021 .- 1470-8728. ; 364:Pt 1, s. 157-163
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Journal article (peer-reviewed)abstract
- Dihydropyrimidine dehydrogenase (DPD) deficiency is an autosomal recessive disease characterized by thymine-uraciluria in homozygous deficient patients. Cancer patients with a partial deficiency of DPD are at risk of developing severe life-threatening toxicities after the administration of 5-fluorouracil. Thus, identification of novel disease-causing mutations is of the utmost importance to allow screening of patients at risk. In eight patients presenting with a complete DPD deficiency, a considerable variation in the clinical presentation was noted. Whereas motor retardation was observed in all patients, no patients presented with convulsive disorders. In this group of patients, nine novel mutations were identified including one deletion of two nucleotides [1039-1042delTG] and eight missense mutations. Analysis of the crystal structure of pig DPD suggested that five out of eight amino acid exchanges present in these patients with a complete DPD deficiency, Pro86Leu, Ser201Arg, Ser492Leu, Asp949Val and His978Arg, interfered directly or indirectly with cofactor binding or electron transport. Furthermore, the mutations Ile560Ser and Tyr211Cys most likely affected the structural integrity of the DPD protein. Only the effect of the Ile370Val and a previously identified Cys29Arg mutation could not be readily explained by analysis of the three-dimensional structure of the DPD enzyme, suggesting that at least the latter might be a common polymorphism. Our data demonstrate for the first time the possible consequences of missense mutations in the DPD gene on the function and stability of the DPD enzyme.
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| 11. |
- Baourakis, George, et al.
(author)
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The impact of e-commerce on agro-food marketing : The case of agricultural cooperatives, firms and consumers in Crete
- 2002
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In: British Food Journal. - : Emerald. - 0007-070X .- 1758-4108. ; 104:8
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Journal article (peer-reviewed)abstract
- This paper is concerned with the impact of e‐commerce on agro‐food marketing. First, a theoretical framework is specified for the Internet as a marketing tool with emphasis on the agro‐food and organic food sections. Subsequently we present the results of a survey that was conducted in order to investigate how Cretan agricultural cooperatives use or tend to use the business methodology of e‐commerce. Consumers and managers of cooperatives in Crete reveal their expectations from the new technology. From this survey valuable information is gained about the practical relations between e‐commerce and the agro‐food market on the island, and divergence from the theoretical framework is noticed.
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| 12. |
- Brindle, Joanne T, et al.
(author)
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Rapid and Nonivasive Diagnosis of the Presence and Severity of Coronary Heart Disease Using 1H-NMR-Based Metabonomics
- 2002
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In: Nature Medicine. - : Springer Science and Business Media LLC. - 1078-8956 .- 1546-170X. ; 8, s. 1439-45
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Journal article (peer-reviewed)abstract
- Although a wide range of risk factors for coronary heart disease have been identified from population studies, these measures, singly or in combination, are insufficiently powerful to provide a reliable, noninvasive diagnosis of the presence of coronary heart disease. Here we show that pattern-recognition techniques applied to proton nuclear magnetic resonance (1H-NMR) spectra of human serum can correctly diagnose not only the presence, but also the severity, of coronary heart disease. Application of supervised partial least squares-discriminant analysis to orthogonal signal-corrected data sets allows >90% of subjects with stenosis of all three major coronary vessels to be distinguished from subjects with angiographically normal coronary arteries, with a specificity of >90%. Our studies show for the first time a technique capable of providing an accurate, noninvasive and rapid diagnosis of coronary heart disease that can be used clinically, either in population screening or to allow effective targeting of treatments such as statins.
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| 14. |
- Gaskell, George, et al.
(author)
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Biotechnology and the European public
- 2000
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In: Nature Biotechnology. - : Springer Science and Business Media LLC. - 1087-0156 .- 1546-1696. ; 18:9, s. 935-938
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Journal article (peer-reviewed)abstract
- The latest European sample survey of public perceptions of biotechnology reveals widespread opposition to genetically modified (GM) food in much of Europe, but public attitudes to medical and environmental applications remain positive.
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| 16. |
- George, Sumod, et al.
(author)
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N-(4-Biphenylyl)urea
- 2001
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In: Acta Crystallographica Section C. - 0108-2701 .- 1600-5759. ; 57:6, s. 777-778
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Journal article (peer-reviewed)
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| 17. |
- Hua, Jianyi, et al.
(author)
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Oxi4503, a novel vascular targeting agent: effects on blood flow and antitumor activity in comparison to combretastatin A-4 phosphate.
- 2003
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In: Anticancer research. - 1791-7530. ; 23:2B, s. 1433-1440
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Journal article (peer-reviewed)abstract
- Oxi4503, which is the diphosphate prodrug of combretastatin A1, is a novel vascular targeting agent from the combretastatin family. Another member of this family, Combretastatin A-4 phosphate (CA4P), is a well-characterized vascular targeting agent already being evaluated in clinical trials. The potential for tumor vascular targeting by Oxi4503 was assessed in a mouse system. This approach aims to shut down the established tumor vasculature, leading to the development of extensive tumor cell necrosis. The vascular effects of Oxi4503 were assessed in the s.c. implanted MDA-MB-231 adenocarcinoma and the MHEC5-T hemangio-endothelioma in SCID mice and in a range of normal tissues. Blood flow was measured by i.v. injection of fluorescence beads, while quantitative fluorescence microscopy was used to measure the spatial heterogeneity of blood flow in tumor sections. Oxi4503 induced the shutdown of tumor blood vessels in a dose-dependent pattern with an ED50 at 3 mg/kg in contrast to 43 mg/kg of CA4P. Quantitative fluorescence microscopy showed that Oxi4503 increased the spatial heterogeneity in tumor blood flow. Oxi4503 affected peripheral tumor regions less than central regions, although this was not as pronounced as seen with CA4P, where only central regions were affected. The vascular shutdown induced by administration of Oxi4503 at a dose of 6 mg/kg resulted in extensive cell loss 24 hours following treatment, which translated into a significant effect on tumor growth. Tumor growth was completely repressed at doses above 12.5 mg/kg of Oxi4503, while doses above 25 mg/kg showed tumor regression and even complete regression in some animals. These results are promising for the use of Oxi4503 as a tumor vascular targeting agent. Moreover the potent antitumor effect when administered as a single agent suggests a different activity profile than CA4P.
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| 18. |
- Kullander, Klas, et al.
(author)
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Ephrin-B3 is the midline barrier that prevents corticospinal tract axons from recrossing, allowing for unilateral motor control
- 2001
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In: Genes & Development. - : Cold Spring Harbor Laboratory. - 0890-9369 .- 1549-5477. ; 15:7, s. 877-888
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Journal article (peer-reviewed)abstract
- Growing axons follow highly stereotypical pathways, guided by a variety of attractive and repulsive cues, before establishing specific connections with distant targets. A particularly well-known example that illustrates the complexity of axonal migration pathways involves the axonal projections of motor neurons located in the motor cortex. These projections take a complex route during which they first cross the midline, then form the corticospinal tract, and ultimately connect with motor neurons in the contralateral side of the spinal cord. These obligatory contralateral connections account for why one side of the brain controls movement on the opposing side of the body. The netrins and slits provide well-known midline signals that regulate axonal crossings at the midline. Herein we report that a member of the ephrin family, ephrin-B3, also plays a key role at the midline to regulate axonal crossing. In particular, we show that ephrin-B3 acts as the midline barrier that prevents corticospinal tract projections from recrossing when they enter the spinal gray matter. We report that in ephrin-B3(-/-) mice, corticospinal tract projections freely recross in the spinal gray matter, such that the motor cortex on one side of the brain now provides bilateral input to the spinal cord. This neuroanatomical abnormality in ephrin-B3(-/-) mice correlates with loss of unilateral motor control, yielding mice that simultaneously move their right and left limbs and thus have a peculiar hopping gait quite unlike the alternate step gait displayed by normal mice. The corticospinal and walking defects in ephrin-B3(-/-) mice resemble those recently reported for mice lacking the EphA4 receptor, which binds ephrin-B3 as well as other ephrins, suggesting that the binding of EphA4-bearing axonal processes to ephrin-B3 at the midline provides the repulsive signal that prevents corticospinal tract projections from recrossing the midline in the developing spinal cord.
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| 23. |
- Svensäter, Gunnel, et al.
(author)
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The acid-tolerant microbiota associated with plaque from initial caries and healthy tooth surfaces
- 2003
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In: Caries Research. - : S. Karger AG. - 0008-6568 .- 1421-976X. ; 37:6, s. 395-403
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Journal article (other academic/artistic)abstract
- The intent of this study was to compare the inherent acid tolerance of bacteria in samples of dental plaque from tooth sites in subjects with and without initial caries. Plaque was collected from approximal surfaces showing early enamel caries and from healthy tooth surfaces in the same subjects, as well as from enamel surfaces of caries-free individuals. In addition to plating on blood agar, the plaque samples were plated directly on non-selective solid agar medium buffered to pH 7.0, 6.0, 5.5, 5.0, 4.5 and 4.0 to avoid any loss of adaptation to acid during primary isolation of plaque bacteria. The results showed that approximately 50% of the total cultivable plaque microbiota from caries, as well as healthy tooth sites, was able to grow at pH 5.5 and 1% at pH 5.0, pH values regarded as critical for the demineralization of tooth enamel. At pH 5.0, members of the genus Streptococcus were the dominant group, but mutans streptococci accounted for less than half of the streptococcal viable count. The other acid-tolerant streptococcal isolates included Streptococcus anginosus, Streptococcus constellatus, Streptococcus gordinii, Streptococcus intermedius, Streptococcus mitis, Streptococcus oralis, Streptococcus salivarius and SStreptococcus sanguis. Analysis of the results indicated that the mutans streptococci in dental plaque were highly variable with respect to acid tolerance, and that both caries and healthy sites harboured significant numbers of mutans streptococci that were not acid-tolerant.
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| 24. |
- Valizadeh, S., et al.
(author)
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Electrochemical deposition of Co nanowire arrays, Quantitative consideration of concentration profiles
- 2001
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In: Electrochimica Acta. - 0013-4686 .- 1873-3859. ; 47:6, s. 865-874
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Journal article (peer-reviewed)abstract
- Electrodeposition of Co into ion track etched polycarbonate membranes by a chronoamperometric method has been studied. The concentration variation and diffusion limiting current during nanoprocessing for growth of Co in nanoelectrode applications are described for two regimes, in the vicinity of the electrode and at the mouth of pores. The behaviour of the as-deposited nanoelectrodes can be modelled as a recessed microelectrode. A diffusion controlled limiting current of the nanodes is studied by the Cottrell equation at short times, i.e. current at-1/2. At longer times, a steady-state current is obtained due to gradually increasing radii, r, of the spherical diffusion zones from each recessed nanode, i.e. current a(1/(r+L)), where L is the membrane thickness. The experimental value of diffusion coefficient D for Co ions was found: D = 2.5 × 10-5 cm2 s-1. XRD and TEM measurements on 250 nm diameter and 20 µm long Co nanowires showed a hexagonal closed packed phase with a <100> texturing. The nanowires exhibited an enhanced magnetic coercivity in comparison to bulk Co. The difference of saturation fields between the parallel and perpendicular orientation fields corresponds well to the expected demagnetisation field of 2pM = 8796 Oe value due to the shape anisotropy in case of an infinite thin Co cylinder. © 2001 Elsevier Science Ltd. All rights reserved.
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| 25. |
- Valizadeh, S., et al.
(author)
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Electrochemical synthesis of Ag/Co multilayered nanowires in porous polycarbonate membranes
- 2002
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In: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 402:1-2, s. 262-271
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Journal article (peer-reviewed)abstract
- The electrodeposition of Ag/Co multilayers into 20 µm thick ion track etched polycarbonate membranes with pore diameter of 120 nm were studied using a single bath containing cobalt sulphate, silver cyanide and potassium pyrophosphate. Cyclic voltammetry and transmission electron microscopy (TEM) was used to determine deposition conditions for pure Ag and 97 wt.% Co layers. The Co rich metallic nanowires were deposited at -1100 mV and the Ag nanowires were deposited at -600 mV vs. Ag/AgCl. By using Faraday's law and linear relation between the charges passed during the time interval for each metal layers and bilayer thickness, a current efficiency of 58% was determined for pulsed deposition of Co. This implies that hydrogen or initial layer re-dissolution of Co during Ag deposition consumes 31% of the charge passed during Co deposition. Multilayered nanowires with 8 and 15 nm thick Ag and Co rich layers, respectively, exhibit well-defined layers in TEM. X-ray diffraction investigations of 20 µm long, Ag, Co and Ag/Co multilayered nanowires show that the Ag deposits exhibited a f.c.c. <111> texturing while the Co deposit exhibited basal plane diffraction of h.c.p. (002) and f.c.c. (111). Magnetic measurements on Ag/Co multilayered nanowires have been made with the external field parallel and perpendicular to the film plane on two series of multilayers: thickness of Co (50 and 15 nm)/Ag (8 nm). In the case of longer cylinder (tCo=50 nm) the axis along the wire starts to become the easy axis (lower saturation field) as expected in the limit where tAg=0 (case of single Co nanowires), due to the shape anisotropy. © 2002 Elsevier Science B.V. All rights reserved.
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