| 1. |
- Abbondanno, U, et al.
(författare)
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The data acquisition system of the neutron time-of-flight facility n_TOF at CERN
- 2005
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 538:1-3, s. 692-702
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Tidskriftsartikel (refereegranskat)abstract
- The n_TOF facility at CERN has been designed for the measurement of neutron capture, fission and (n, xn) cross-sections with high accuracy. This requires a flexible and-due to the high instantaneous neutron flux-almost dead time free data acquisition system. A scalable and versatile data solution has been designed based on 8-bit flash-ADCs with sampling rates up to 2 GHz and 8 Mbyte memory buffer. The software is written in C and C++ and is running on PCs equipped with RedHat Linux.
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| 2. |
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| 3. |
- Valle-Delgado, J. J., et al.
(författare)
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Adhesion forces between protein layers studied by means of atomic force microscopy
- 2006
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 22:11, s. 5108-5114
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Tidskriftsartikel (refereegranskat)abstract
- Adhesion forces between different protein layers adsorbed on different substrates in aqueous media have been measured by means of an atomic force microscope using the colloid probe technique. The effects of the loading force, the salt concentration and pH of the medium, and the electrolyte type on the strength, the pull-off distance, and the separation energy of such adhesion forces have been analyzed in depth. Two very different proteins (bovine serum albumin and apoferritin) and two dissimilar substrates (silica and polystyrene) were used in the experiments. The results clearly point out a very important contribution of the electrostatic interactions in the adhesion between protein layers.
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| 4. |
- Valle-Delgado, J. J., et al.
(författare)
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Existence of hydration forces in the interaction between apoferritin molecules adsorbed on silica surfaces
- 2005
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Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 21:21, s. 9544-9554
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Tidskriftsartikel (refereegranskat)abstract
- The atomic force microscope, together with the colloid probe technique, has become a very useful instrument to measure interaction forces between two surfaces. Its potential has been exploited in this work to study the interaction between protein (apoferritin) layers adsorbed on silica surfaces and to analyze the effect of the medium conditions (pH, salt concentration, salt type) on such interactions. It has been observed that the interaction at low salt concentrations is dominated by electrical double layer (at large distances) and steric forces (at short distances), the latter being due to compression of the protein layers. The DLVO theory fits these experimental data quite well. However, a non-DLVO repulsive interaction, prior to contact of the protein layers, is observed at high salt concentration above the isoelectric point of the protein. This behavior could be explained if the presence of hydration forces in the system is assumed. The inclusion of a hydration term in the DLVO theory (extended DLVO theory) gives rise to a better agreement between the theoretical fits and the experimental results. These results seem to suggest that the hydration forces play a very important role in the stability of the proteins in the physiological media.
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| 5. |
- Valle-Delgado, J. J., et al.
(författare)
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Hydration forces between silica surfaces : Experimental data and predictions from different theories
- 2005
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 123, s. 034708-
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Tidskriftsartikel (refereegranskat)abstract
- Silica is a very interesting system that has been thoroughly studied in the last decades. One of the most outstanding characteristics of silica suspensions is their stability in solutions at high salt concentrations. In addition to that, measurements of direct-interaction forces between silica surfaces, obtained by different authors by means of surface force apparatus or atomic force microscope (AFM), reveal the existence of a strong repulsive interaction at short distances (below 2 nm) that decays exponentially. These results cannot be explained in terms of the classical Derjaguin, Landau, Verwey, and Overbeek (DLVO) theory, which only considers two types of forces: the electrical double-layer repulsion and the London-van der Waals attraction. Although there is a controversy about the origin of the short-range repulsive force, the existence of a structured layer of water molecules at the silica surface is the most accepted explanation for it. The overlap of structured water layers of different surfaces leads to repulsive forces, which are known as hydration forces. This assumption is based on the very hydrophilic nature of silica. Different theories have been developed in order to reproduce the exponentially decaying behavior (as a function of the separation distance) of the hydration forces. Different mechanisms for the formation of the structured water layer around the silica surfaces are considered by each theory. By the aid of an AFM and the colloid probe technique, the interaction forces between silica surfaces have been measured directly at different pH values and salt concentrations. The results confirm the presence of the short-range repulsion at any experimental condition (even at high salt concentration). A comparison between the experimental data and theoretical fits obtained from different theories has been performed in order to elucidate the nature of this non-DLVO repulsive force.
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| 6. |
- Steffen, Annika, et al.
(författare)
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Anthropometry and Esophageal Cancer Risk in the European Prospective Investigation into Cancer and Nutrition
- 2009
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Ingår i: Cancer Epidemiology Biomarkers & Prevention. - 1538-7755 .- 1055-9965. ; 18:7, s. 2079-2089
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Tidskriftsartikel (refereegranskat)abstract
- Background: Increasing evidence suggests that general obesity [measured by body mass index (BMI)] is positively associated with risk of esophageal adenocarcinoma (EAC). In contrast, previous studies have shown inverse relations with esophageal squamous cell carcinoma (ESCC). However, it is still unclear whether body fat distribution, particularly abdominal obesity, is associated with each type of esophageal cancer. Methods: We applied multivariable adjusted Cox proportional hazards regression to investigate the association between anthropometric measures and risk of EAC and ESCC among 346,554 men and women participating in the European Prospective Investigation into Cancer and Nutrition. All statistical tests were two sided. Results: During 8.9 years of follow-up, we documented 88 incident cases of EAC and 110 cases of ESCC. BMI, waist circumference, and waist-to-hip ratio (WHR) were positively associated with EAC risk [highest versus lowest quintile; relative risk (RR), 2.60; 95% confidence interval (95% CI), 1.23-5.51; P-trend < 0.01; RR, 3.07; 95% CI, 1.35-6.98; P-trend < 0.003; and RR, 2.12; 95% CI, 0.98-4.57; P-trend < 0.004]. In contrast, BMI and waist circumference were inversely related to ESCC risk, whereas WHR showed no association with ESCC. In stratified analyses, BMI and waist circumference were significantly inversely related to ESCC only among smokers but not among nonsmokers. However, when controlled for BMI, we found positive associations for waist circumference and WHR with ESCC, and these associations were observed among smokers and nonsmokers. Conclusion: General and abdominal obesity were associated with higher EAC risk. Further, our study suggests that particularly an abdominal body fat distribution might also be a risk factor for ESCC. (Cancer Epidemiol Biomarkers Prev 2009;18(7):2079-89)
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