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排序方式: 共有217条查询结果,搜索用时 54 毫秒
1.
This article concerns seasonal variations in the phosphate concentrations in two coastal lagoons near Montpellier (Mediterranean
coast, France). The o-P concentration in the overlying water is highest during summer. The role of the sediment, particularly
that of the different P fractions in the sediment, is discussed. Significant variations, especially in the FeOOH ≈ P fraction,
occur. For both Tot-Psed and the Fe00H≈P fraction a gradient from surface to bottom is observed, as well as a distinct decrease in the FeOOH≈P fraction
in the surface sediments during summer and autumn. Variations in the FeOOH≈P fraction appear to be compensated by variations
in the CaC03≈P fraction. These variations appear to be determined by the ferric hydroxide concentration. This compound represents only
a small part (maximally 15%) of the total iron in the sediments and is related to the dissolved oxygen content of the immediately
overlying water. Besides the fractions o-P, Fe(OOH)≈P, a large part of the CaC03≈P fraction is potentially bioavailable. A large proportion of the Tot-Psed is therefore bioavailable.[/p] 相似文献
2.
Xuan Li Eduardo Ximenes Mary Anne Roshni Amalaradjou Hunter B. Vibbert Kirk Foster Jim Jones Xingya Liu Arun K. Bhunia Michael R. Ladisch 《Applied and environmental microbiology》2013,79(22):7048-7054
This paper reports an approach to enable rapid concentration and recovery of bacterial cells from aqueous chicken homogenates as a preanalytical step of detection. This approach includes biochemical pretreatment and prefiltration of food samples and development of an automated cell concentration instrument based on cross-flow microfiltration. A polysulfone hollow-fiber membrane module having a nominal pore size of 0.2 μm constitutes the core of the cell concentration instrument. The aqueous chicken homogenate samples were circulated within the cross-flow system achieving 500- to 1,000-fold concentration of inoculated Salmonella enterica serovar Enteritidis and naturally occurring microbiota with 70% recovery of viable cells as determined by plate counting and quantitative PCR (qPCR) within 35 to 45 min. These steps enabled 10 CFU/ml microorganisms in chicken homogenates or 102 CFU/g chicken to be quantified. Cleaning and sterilizing the instrument and membrane module by stepwise hydraulic and chemical cleaning (sodium hydroxide and ethanol) enabled reuse of the membrane 15 times before replacement. This approach begins to address the critical need for the food industry for detecting food pathogens within 6 h or less. 相似文献
3.
Seockmo Ku Eduardo Ximenes Thomas Kreke Kirk Foster Justin L. Couetil Jessica Zuponcic Xiaojun Zhao Lori Hoagland Amanda J. Deering Michael R. Ladisch 《Biotechnology progress》2019,35(6):e2874
To attain Salmonella detection thresholds in spinach suspensions using enrichment media requires at least 24 hr. Separation and concentration of selected microorganisms via microfiltration and microfugation reduce time for sample preparation, especially when working with large volumes of vegetable suspensions. This facilitates accelerated detection of Salmonella in spinach suspensions, and may contribute to effectively monitoring this pathogen before it reaches the consumer. We report a microfiltration-based protocol for accelerated sample preparation to concentrate and recover ≤1 colony forming unit (CFU) Salmonella/g pathogen-free spinach. Store-bought samples of spinach and a spinach plant subjected to two environmental conditions (temperature and light exposure) during its production were tested. The overall procedure involves extraction with buffer, a short enrichment step, prefiltration using a nylon filter, crossflow hollow fiber microfiltration, and retentate centrifugation to bring microbial cells to detection levels. Based on 1 CFU Salmonella/g frozen spinach, and a Poisson distribution statistical analyses with 99% probability, we calculated that 3 hr of incubation, when followed by microfiltration, is sufficient to reach the 2 log concentration required for Salmonella detection within 7 hr. Longer enrichment times (5 hr or more) is needed for concentrations lower than 1 CFU Salmonella/g of ready to eat spinach. The recovered microbial cells were identified and confirmed as Salmonella using both polymerase chain reaction (PCR) and plating methods. Different environmental conditions tested during production did not affect Salmonella viability; this demonstrated the broad adaptability of Salmonella and emphasized the need for methods that enable efficient monitoring of production for the presence of this pathogen. 相似文献
4.
Nicky HGM Peters Inne HM Borel Rinkes Willem PTM Mali Maurice AAJ van den Bosch Remmert K Storm Peter W Plaisier Erwin de Boer Adriaan J van Overbeeke Petra HM Peeters 《Trials》2007,8(1):1-7
Background
In orthodontic treatment, anchorage control is a fundamental aspect. Usually conventional mechanism for orthodontic anchorage control can be either extraoral or intraoral that is headgear or intermaxillary elastics. Their use are combined with various side effects such as tipping of occlusal plane or undesirable movements of teeth. Especially in cases, where key-teeth are missing, conventional anchorage defined as tooth-borne anchorage will meet limitations. Therefore, the use of endosseous implants for anchorage purposes are increasingly used to achieve positional stability and maximum anchorage.Methods/Design
The intended study is designed as a prospective, multicenter randomized controlled trial (RCT), comparing and contrasting the effect of early loading of palatal implant therapy versus implant loading after 12 weeks post implantation using the new ortho-implant type II anchor system device (Orthosystem Straumann, Basel, Switzerland). 124 participants, mainly adult males or females, whose diagnoses require temporary stationary implant-based anchorage treatment will be randomized 1:1 to one of two treatment groups: group 1 will receive a loading of implant standard therapy after a healing period of 12 week (gold standard), whereas group 2 will receive an early loading of orthodontic implants within 1 week after implant insertion. Participants will be at least followed for 12 months after implant placement. The primary endpoint is to investigate the behavior of early loaded palatal implants in order to find out if shorter healing periods might be justified to accelerate active orthodontic treatment. Secondary outcomes will focus e.g. on achievement of orthodontic treatment goals and quantity of direct implant-bone interface of removed bone specimens. As tertiary objective, a histologic and microtomography evaluation of all retrieved implants will be performed to obtain data on the performance of the SLA surface in human bone evaluation of all retrieved implants. Additionally, resonance frequency analysis (RFA, Osstell? mentor) will be used at different times for clinically monitoring the implant stability and for histological comparison in order to measure the reliability of the resonance frequency measuring device.Trial registration
Current Controlled Trials ISRCTN97142521. 相似文献5.
Lutzomyia evandroi Costa Lima and Antunes, 1936 is found in Rio Grande do Norte, northeastern Brazil, in areas of visceral and mucocutaneous leishmaniasis and follows the same geographic distribution of L. longipalpis. The biological cycle, oviposition, morphological and behavioral characteristics of the species were studied under experimental conditions. The average number of eggs per wild caught female varied from 21 to 50 eggs along the year, with a peak occurring between January and March and another in August, with oviposition lasting for 4 to 12 days. The mean larval phase was 24 days. Ovipositing rates were influenced by rainfall and temperature indexes, with an increase of eggs per oviposition at the beginning and at the end of the rainy season, and a decrease at the peak of the rainy season. 相似文献
6.
Glucose transport and utilization are altered in the brain of rats deficient in n-3 polyunsaturated fatty acids 总被引:1,自引:0,他引:1
Ximenes da Silva A Lavialle F Gendrot G Guesnet P Alessandri JM Lavialle M 《Journal of neurochemistry》2002,81(6):1328-1337
Long-chain polyunsaturated (n-3) fatty acids have been reported to influence the efficiency of membrane receptors, transporters and enzymes. Because the brain is particularly rich in docosahexaenoic acid (DHA, 22:6 n-3), the present study addresses the question of whether the 22:6 n-3 fatty acid deficiency induces disorder in regulation of energy metabolism in the CNS. Three brain regions that share a high rate of energy metabolism were studied: fronto-parietal cortex, hippocampus and suprachiasmatic nucleus. The effect of the diet deficient in n-3 fatty acids resulted in a 30-50% decrease in DHA in membrane phospholipids. Moreover, a 30% decrease in glucose uptake and a 20-40% decrease in cytochrome oxidase activity were observed in the three brain regions. The n-3 deficient diet also altered the immunoreactivity of glucose transporters, namely GLUT1 in endothelial cells and GLUT3 in neurones. In n-3 fatty acid deficient rats, GLUT1-immunoreactivity readily detectable in microvessels became sparse, whereas the number of GLUT3 immunoreactive neurones was increased. However, western blot analysis showed no significant difference in GLUT1 and GLUT3 protein levels between rats deficient in n-3 fatty acids and control rats. The present results suggest that changes in energy metabolism induced by n-3 deficiency could result from functional alteration in glucose transporters. 相似文献
7.
Jolanda?HM?van Bilsen Josée?PA?Wagenaar-Hilbers Maarten?JF?van der Cammen Mariska?EA?van Dijk Willem?van Eden Marca?HM?WaubenEmail author 《Arthritis research & therapy》2002,4(4):R2
We have recently found that matrix metalloproteinases (MMPs) are targets for T-cell and B-cell reactivity in experimental
arthritis. In the present article, we investigate whether modulation of MMP-specific T-cell responses could influence the
course of adjuvant arthritis (AA). Lewis rats were treated nasally with MMP peptides prior to or after AA induction. Administration
of the MMP-10 or the MMP-16 peptide prior to AA induction reduced the arthritic symptoms. In contrast, administration of the
MMP-10 peptide after AA induction aggravated the arthritic symptoms. The present study shows the possible usefulness of MMP
peptides for immunotherapy. However, a clear understanding of proper timing of peptide administration is crucial for the development
of such therapies. 相似文献
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10.
Cecilie?M?MejdellEmail author Grete?HM?J?rgensen Therese?Rehn Kjersti?Fremstad Linda?Keeling Knut?E?B?e 《Acta veterinaria Scandinavica》2010,52(1):68