| 1. |
- Adcox, K, et al.
(författare)
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PHENIX detector overview
- 2003
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - 0167-5087. ; 499:2-3, s. 469-479
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Tidskriftsartikel (refereegranskat)abstract
- The PHENIX detector is designed to perform a broad study of A-A, p-A, and p-p collisions to investigate nuclear matter under extreme conditions. A wide variety of probes, sensitive to all timescales, are used to study systematic variations with species and energy as well as to measure the spin structure of the nucleon. Designing for the needs of the heavy-ion and polarized-proton programs has produced a detector with unparalleled capabilities. PHENIX measures electron and muon pairs, photons, and hadrons with excellent energy and momentum resolution. The detector consists of a large number of subsystems that are discussed in other papers in this volume. The overall design parameters of the detector are presented. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 2. |
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| 3. |
- Adler, SS, et al.
(författare)
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PHENIX on-line systems
- 2003
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - 0167-5087. ; 499:2-3, s. 560-592
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Tidskriftsartikel (refereegranskat)abstract
- The PHENIX On-Line system takes signals from the Front End Modules (FEM) on each detector subsystem for the purpose of generating events for physics analysis. Processing of event data begins when the Data Collection Modules (DCM) receive data via fiber-optic links from the FEMs. The DCMs format and zero suppress the data and generate data packets. These packets go to the Event Builders (EvB) that assemble the events in final form. The Level-1 trigger (LVL1) generates a decision for each beam crossing and eliminates uninteresting events. The FEMs carry out all detector processing of the data so that it is delivered to the DCMs using a standard format. The FEMs also provide buffering for LVL1 trigger processing and DCM data collection. This is carried out using an architecture that is pipelined and deadtimeless. All of this is controlled by the Master Timing System (MTS) that distributes the RHIC clocks. A Level-2 trigger (LVL2) gives additional discrimination. A description of the components and operation of the PHENIX On-Line system is given and the solution to a number of electronic infrastructure problems are discussed. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 4. |
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| 5. |
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| 6. |
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| 7. |
- Francisco, J D, et al.
(författare)
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Liquid crystalline properties and extractability of monoolein-water systems by supercritical carbon dioxide
- 2003
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Ingår i: Colloids and Surfaces A: Physicochemical and Engineering Aspects. - 0927-7757. ; 213:1, s. 69-78
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Tidskriftsartikel (refereegranskat)abstract
- The influence of phase structure on the extraction recovery of monoolein from monoolein-water systems by supercritical carbon dioxide was investigated. Two monoolein-water mi tures at concentrations of 9 wt% water and 18 wt% water, respectively, were studied. H-2-NMR was used to monitor changes of the phase structures in supercritical conditions. The results showed that the phase structure and the water-monoolein interactions play a role on the extraction yield. The monoolein recovery was higher in the 9 wt% water sample in which L-alpha phase was present compared to the 18 wt% water sample in which the L-alpha melted to yield a L-2 phase. When the phase structures were the same in both samples, the extraction recovery was determined by the solubility properties of the components of the system. The changes due to the presence of supercritical carbon dioxide were shown also to depend on the water concentration of the monoolein-water mixture besides the temperature. The 18 wt% mixture showed a L-2 phase structure in all the range of the temperature investigated while the 9 wt% water mixture showed phase changes from L-alpha phase to L-2 phase in the same temperature range. (C) 200 Elsevier Science B.V. All rights reserved.
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| 8. |
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| 9. |
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| 10. |
- Mathiasson, Lennart, et al.
(författare)
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Development of methods for the determination of vitamins A, E and beta-carotene in processed foods based on supercritical fluid extraction: a collaborative study.
- 2002
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Ingår i: Food Additives and Contaminants. - : Informa UK Limited. - 0265-203X. ; 19:7, s. 632-646
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Tidskriftsartikel (refereegranskat)abstract
- New methodologies based on supercritical fluid extraction (SFE) have been developed for the determination of fat-soluble vitamins in processed foods. The results obtained so far indicate that SFE is well suited to extraction of fat-soluble vitamins from food products, although validation work is required to establish accuracy and precision. The vitamins investigated were A, E and beta-carotene, and the processed foods were UHT milk, milk powder, minced meat, liver paste, infant formula, canned baby food and margarine. Extraction equipment employed analyte collection on either a solid-phase trap or in a solvent. After extraction, the samples were saponified and the vitamins determined using reversed-phase liquid chromatography with ultraviolet or fluorescence detection. Sample throughput was at least 12 samples day(-1), i.e. at least twice the number achievable with a conventional extraction methodology. The detection limits for the vitamins in different processed foods were well below 0.1 microg g(-1). Recoveries (in comparison with vitamin levels obtained using conventional solvent extraction) were close to 100% for experienced personal with access to modern automatic equipment. To reach this level, it was necessary to protect the vitamins with an antioxidant during the different steps of the analysis procedure, to add methanol or ethanol to the extraction cell to facilitate the analyte extraction from the food matrix, and when using a solid-phase trap, to employ a fractionated extraction-elution procedure to prevent breakthrough losses. The developed methods were tested in a validation exercise between five laboratories, which had taken part in the method development, and in an intercomparison between 10 laboratories including laboratories with less experience of vitamin determination. The within-laboratory RSD was generally
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| 11. |
- Palchetti, I, et al.
(författare)
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Disposable screen-printed electrodes (SPE) mercury-free for lead detection
- 2000
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Ingår i: Analytical Letters. - : Taylor andamp;amp; Francis. - 0003-2719 .- 1532-236X. ; 33:7, s. 1231-1246
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Tidskriftsartikel (refereegranskat)abstract
- Strategies to modify screen-printed electrodes (SPE) for lead determination are reported. Dithizone was mixed with graphite ink to obtain a modified screen-printed strip to detect ppb levels of lead(II) (detection limit 12 mu g/l) using square wave anodic stripping voltammetry (SWASV). In addition, screen-printed electrodes were also modified by casting a few mu l of a Nafion(R) solution onto the working electrode surface. In this case, ppb levels of lead were detected (detection limit 15 mu g/l), using potentiometric stripping analysis (PSA). The addition of an ionophore to Nafion(R) polymer was also investigated, but this did not yield a significant improvement.
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| 12. |
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| 13. |
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| 14. |
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| 15. |
- Pavlou, AK, et al.
(författare)
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Use of an electronic nose system for diagnoses of urinary tract infections
- 2002
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Ingår i: Biosensors & bioelectronics. - : Elsevier Science B.V., Amsterdam.. - 0956-5663 .- 1873-4235. ; 17:10, s. 893-899
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Tidskriftsartikel (refereegranskat)abstract
- The use of volatile production patterns produced by bacterial contaminants in urine samples were examined using electronic nose technology. In two experiments 25 and 45 samples from patients were analysed for specific bacterial contaminants using agar culture techniques and the major UTI bacterial species identified. These samples were also analysed by incubation in a volatile generation test tube system for 4-5 h. The volatile production patterns were then analysed using an electronic nose system with 14 conducting polymer sensors. In the first experiment analysis of the data using a neural network (NN) enabled identification of all but one of the samples correctly when compared to the culture information. Four groups could be distinguished, i.e. normal urine, Escherichia coli infected, Proteus spp. and Staphylococcus spp. In the second experiment it was again possible to use NN systems to examine the volatile production patterns and identify 18 of 19 unknown UTI cases. Only one normal patient sample was mis-identified as an E coli infected sample. Discriminant function analysis also differentiated between normal urine samples, that infected with E coli and with Staphylococcus spp. This study has shown the potential for early detection of microbial contaminants in urine samples using electronic nose technology for the first time. These findings will have implications for the development of rapid systems for use in clinical practice. (C) 2002 Elsevier Science B.V. All rights reserved.
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| 16. |
- Piletsky, SA, et al.
(författare)
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Recognition of ephedrine enantiomers by molecularly imprinted polymers designed using a computational approach
- 2001
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Ingår i: The Analyst. - : Royal Society of Chemistry. - 0003-2654 .- 1364-5528. ; 126:10, s. 1826-1830
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Tidskriftsartikel (refereegranskat)abstract
- A new approach to the computational design of molecularly imprinted polymers (MIP) specific for ephedrine is presented. A virtual library of functional monomers was developed and screened against the template using molecular modelling software. The monomers giving the highest binding score were co-polymerized with a cross-linker in the presence of ephedrine. Control (blank) polymers were prepared under the same conditions but in the absence of the template. A good correlation was found between the modelling results and performance of the materials in an HPLC study. A MIP based on one of the selected monomers-hydroxyethyl methacrylate-gave a separation of ephedrine enantiomers with a separation factor a of 1.42-2.09 (depending on temperature). This figure is larger than the a values generally obtained with commercially available chiral phases. It is anticipated that the computational approach will be of use for the rational design of MIPS and the prediction of polymer affinity and specificity.
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| 17. |
- Squitieri, Ferdinando, et al.
(författare)
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Homozygosity for CAG mutation in Huntington disease is associated with a more severe clinical course.
- 2003
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Ingår i: Brain. - : Oxford University Press (OUP). - 0006-8950 .- 1460-2156. ; 126:Pt 4, s. 946-55
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Tidskriftsartikel (refereegranskat)abstract
- Huntington disease is caused by a dominantly transmitted CAG repeat expansion mutation that is believed to confer a toxic gain of function on the mutant protein. Huntington disease patients with two mutant alleles are very rare. In other poly(CAG) diseases such as the dominant ataxias, inheritance of two mutant alleles causes a phenotype more severe than in heterozygotes. In this multicentre study, we sought differences in the disease features between eight homozygotes and 75 heterozygotes for the Huntington disease mutation. We identified subjects homozygous for the Huntington disease mutation by DNA testing and compared their clinical features (age at onset, symptom presentation, disease severity and disease progression) with those of a group of heterozygotes, who were assessed longitudinally. The age at onset of symptoms in the homozygote cases was within the range expected for heterozygotes with the same CAG repeat lengths, whereas homozygotes had a more severe clinical course. The observation of a more rapid decline in motor, cognitive and behavioural symptoms in homozygotes was consistent with the extent of neurodegeneration as available at imaging in three patients, and at the post-mortem neuropathological report in one case. Our analysis suggests that although homozygosity for the Huntington disease mutation does not lower the age at onset of symptoms, it affects the phenotype and the rate of disease progression. These data, once confirmed in a larger series of patients, point to the possibility that the mechanisms underlying age at onset and disease progression in Huntington disease may differ.
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| 18. |
- Tombelli, S, et al.
(författare)
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A DNA piezoelectric biosensor assay coupled with a polymerase chain reaction for bacterial toxicity determination in environmental samples
- 2000
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Ingår i: Analytica Chimica Acta. - : Elsevier Science B.V., Amsterdam.. - 0003-2670 .- 1873-4324. ; 418:1
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we report the realisation of a DNA piezoelectric biosensor coupled with the polymerase chain reaction (PCR) for the detection of a specific bacterial toxicity factor. Biotinylated 23-mer probes were immobilised on the streptavidin coated gold surface of a quartz crystal; streptavidin was covalently bound to the thiol/dextran modified gold surface. The hybridisation of the immobilised probe with a synthetic oligonucleotide was investigated; the absence of non-specific adsorption was verified using a non-complementary oligonucleotide. Many cycles of measurements can be performed on the same crystal surface by regenerating the single strand with 1 mM HCl. The same hybridisation reaction was then performed using real samples of DNA extracted from bacteria and amplified by PCR. The PCR product was a fragment of a specific gene of Aeromonas hydrophila. The piezoelectric biosensor was able to distinguish samples containing the gene or not; in this way it was possible to determine the pathogenicity of different Aeromonas strains isolated from water, vegetables or human specimens. Experiments with non-specific samples confirmed the absence of adsorption or non-specific effects on the quartz crystal treated with the reported procedure. (C) 2000 Elsevier Science B.V. All rights reserved.
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| 19. |
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| 20. |
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| 21. |
- Turner, C, et al.
(författare)
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Supercritical fluid extraction and chromatography for fat-soluble vitamin analysis.
- 2001
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Ingår i: Journal of Chromatography A. - 0021-9673. ; 936:1, s. 37-215
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Tidskriftsartikel (refereegranskat)abstract
- Extraction and chromatographic separation of fat-soluble vitamins is a challenging task, due to the sensitivity of these compounds towards light, oxygen, heat and pH. In light of this, supercritical fluid extraction (SFE) and supercritical fluid chromatography (SFC) are attractive techniques as they function at considerably milder conditions than conventional solvent-based analytical techniques. Moreover, supercritical techniques consume much less amounts of organic solvents than conventional ones. This review gives a brief description of suitable supercritical media as well as basic theory on SFE and SFC processes. Furthermore, guidelines are provided for optimizing the important extraction and separation parameters to facilitate a successful method development. Finally, applications employing SFE and/or SFC for fat-soluble vitamin enrichment and final determination are reviewed.
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| 22. |
- Turner, David R., 1951, et al.
(författare)
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The SWEDARP 1997/98 Expedition.
- 2004
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Ingår i: Deep Sea Research Part II. ; 51, s. 2543-2879
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Tidskriftsartikel (refereegranskat)
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| 23. |
- Williams, Amanda M, et al.
(författare)
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Intestinal alpha beta T cells differentiate and rearrange antigen receptor genes in situ in the human infant.
- 2004
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Ingår i: Journal of immunology (Baltimore, Md. : 1950). - 0022-1767. ; 173:12, s. 7190-9
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Tidskriftsartikel (refereegranskat)abstract
- Intestinal Ag exposure during neonatal life influences appropriate adult immune responses. To define the mechanisms shaping the T cell repertoire during this period, we examined T cell differentiation and receptor diversity in the intestine of human infants. Developmental phenotypes of intraepithelial and lamina propria intestinal T cells from infants aged 1 day to 2 years were assessed ex vivo by flow cytometry and in situ by triple-fluorescent immunohistochemistry. Gene recombination-specific enzymes were assessed by PCR. TCR beta-chain V region gene diversity was determined by sequencing. Several different early lineage T cell populations were present neonatally: CD3(+)4(-)8(-) T cells were present at birth and numbers decreased during the neonatal period; CD3(+)4(+)8(+) T cells were present in low numbers throughout infancy; and CD3(+)4(+)8(-) or CD3(+)4(-)8(+) T cells increased with age. Very early lineage T cells, CD3(-)2(-)7(+) and CD3(-)2(+)7(+), were present neonatally, but were essentially absent at 1 year. Most lamina propria T cells differentiated rapidly after birth, but maturation of intraepithelial T cells took place over 1 year. Intestinal samples from infants less than 6 mo old contained transcripts of T early alpha and TdT, and 15 of 19 infant samples contained mRNA for RAG-1, some coexpressing RAG-2. TCR beta-chain repertoires were polyclonal in infants. Immature T cells, pre-T cells, and genes involved in T cell recombination were found in the intestine during infancy. T cell differentiation occurs within the neonatal human intestine, and the TCR repertoire of these developing immature T cells is likely to be influenced by luminal Ags. Thus, mucosal T cell responsiveness to environmental Ag is shaped in situ during early life.
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