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11.
Determination of inorganic ions in mineral water by gradient elution moving boundary electrophoresis
A sensitive method was developed for the determination of the major inorganic ions in commercial mineral waters using gradient elution moving boundary electrophoresis with capacitively coupled contactless conductivity detection. This application was the first to demonstrate the separation of cations and anions simultaneously using gradient elution moving boundary electrophoresis. Seven ionic analytes (calcium, chloride, magnesium, nitrate, potassium, sodium, and sulfate) were separated in less than 7 min with detection values in the low μmol/L to sub-μmol/L range. Calculated values of the major ions in three commercial mineral waters were compared to reported values with good correlation. In another application, phosphate and arsenate were separated in less than 2 min with limits of detection of 300 and 140 nmol/L, respectively. For all standard analyses, the RSD for migration times and peak areas were under 3%. 相似文献
12.
Jia G Takayama Y Flanigan DC Kaeding CC Zhou J Chaudhari A Clark D Sammet S Liang J Choi S Knopp MV 《Magnetic resonance imaging》2011,29(3):335-341
Purpose
To establish the feasibility of chemical exchange saturation transfer (proteinCEST) MRI in the differentiation of osteoarthritis (OA) knee joints from non-OA joints by detecting mobile protein and peptide levels in synovial fluid by determining their relative distribution.Materials and Methods
A total of 25 knees in 11 men and 12 women with knee injuries were imaged using whole knee joint proteinCEST MRI sequence at 3 T. The joint synovial fluid was segmented and the asymmetric magnetization transfer ratio at 3.5 ppm MTRasym (3.5 ppm) was calculated to assess protein content in the synovial fluid. The 85th percentile of synovial fluid MTRasym (3.5 ppm) distribution profile was compared using the independent Student's t test. The diagnostic performance of the 85th percentile of synovial fluid MTRasym (3.5 ppm) in differentiating OA and non-OA knee joints was evaluated.Results
The 85th percentile of synovial fluid MTRasym (3.5 ppm) in knee joints with OA was 8.6%±3.4% and significantly higher than that in the knee joints without OA (6.3%±1.4%, P<.05). A knee joint with an 85th percentile of synovial fluid MTRasym (3.5 ppm) greater than 7.7% was considered to be an OA knee joint. With the threshold, the sensitivity, specificity and overall accuracy for differentiating knee joints with OA from the joints without OA were 54% (7/13), 92% (11/12) and 72% (18/25), respectively.Conclusion
proteinCEST MRI appears feasible as a quantitative methodology to determine mobile protein levels in synovial fluid and identify patterns characteristic for OA disease. 相似文献13.
Elif Tokar Erdemir Rajan Batta Peter A. Rogerson Alan Blatt Marie Flanigan 《European Journal of Operational Research》2010
Aeromedical and ground ambulance services often team up in responding to trauma crashes, especially when the emergency helicopter is unable to land at the crash scene. We propose location-coverage models and a greedy heuristic for their solution to simultaneously locate ground and air ambulances, and landing zones (transfer points). We provide a coverage definition based on both response time and total service time, and consider three coverage options; only ground emergency medical services (EMS) coverage, only air EMS coverage, or joint coverage of ground and air EMS in which the patient is transferred from an ambulance into an emergency helicopter at a transfer point. To analyze this complex coverage situation we develop two sets of models, which are variations of the Location Set Covering Problem (LSCP) and the Maximal Covering Location Problem (MCLP). These models address uncertainty in spatial distribution of motor vehicle crash locations by providing coverage to a given set of both crash nodes and paths. The models also consider unavailability of ground ambulances by drawing upon concepts from backup coverage models. We illustrate our results on a case study that uses crash data from the state of New Mexico. The case study shows that crash node and path coverage percentage values decrease when ground ambulances are utilized only within their own jurisdiction. 相似文献
14.
Location coverage models with demand originating from nodes and paths: Application to cellular network design 总被引:3,自引:0,他引:3
Elif Tokar Erdemir Rajan Batta Seth Spielman Peter A. Rogerson Alan Blatt Marie Flanigan 《European Journal of Operational Research》2008,190(3):610-632
Location covering problems, though well studied in the literature, typically consider only nodal (i.e. point) demand coverage. In contrast, we assume that demand occurs from both nodes and paths. We develop two separate models – one that handles the situation explicitly and one which handles it implicitly. The explicit model is formulated as a Quadratic Maximal Covering Location Problem – a greedy heuristic supported by simulated annealing (SA) that locates facilities in a paired fashion at each stage is developed for its solution. The implicit model focuses on systems with network structure – a heuristic algorithm based on geometrical concepts is developed. A set of computational experiments analyzes the performance of the algorithms, for both models. We show, through a case study for locating cellular base stations in Erie County, New York State, USA, how the model can be used for capturing demand from both stationary cell phone users as well as cell phone users who are in moving vehicles. 相似文献
15.
Glycosaminoglycan Chemical Exchange Saturation Transfer (gagCEST) is an important molecular MRI methodology developed to assess changes in cartilage GAG concentrations. The correction for B0 field inhomogeneity is technically crucial in gagCEST imaging. This study evaluates the accuracy of the B0 estimation determined by the dual gradient echo method and the effect on gagCEST measurements. The results were compared with those from the commonly used z-spectrum method. Eleven knee patients and three healthy volunteers were scanned. Dual gradient echo B0 maps with different ?TE values (1, 2, 4, 8, and 10 ms) were acquired. The asymmetry of the magnetization transfer ratio at 1 ppm offset referred to the bulk water frequency, MTRasym(1 ppm), was used to quantify cartilage GAG levels. The B0 shifts for all knee patients using the z-spectrum and dual gradient echo methods are strongly correlated for all ?TE values used (r = 0.997 to 0.786, corresponding to ?TE = 10 to 1 ms). The corrected MTRasym(1 ppm) values using the z-spectrum method (1.34% ± 0.74%) highly agree only with those using the dual gradient echo methods with ?TE = 10 ms (1.72% ± 0.80%; r = 0.924) and 8 ms (1.50% ± 0.82%; r = 0.712). The dual gradient echo method with longer ?TE values (more than 8 ms) has an excellent correlation with the z-spectrum method for gagCEST imaging at 3 T. 相似文献
16.
7,7'-Dihydroxy-8,8'-biquinolyl (azaBINOL) was prepared from 2-chloroaniline in four steps: (1) the Skraup reaction, (2) Ni-catalyzed reductive coupling of 8-chloroquinoline, (3) Pd(II)-catalyzed double C-H functionalization of 8,8'-biquinolyl mediated by PhI(OAc)(2), and (4) saponification. During the third step, an axially chiral (atropos type) biaryl molecule was directly generated from an essentially achiral (tropos type) biaryl starting material. 相似文献
17.
Matthew J Henchey Rajan Batta Alan Blatt Marie Flanigan Kevin Majka 《The Journal of the Operational Research Society》2015,66(4):570-578
This paper presents tests conducted on routes determined from a Dijkstra-based shortest path problem and a Variance-Constrained Shortest Path problem under varying conditions of traffic and weather in a simulated ‘smart environment’. Utilizing envisioned future advanced transportation systems’ real-time information on traffic parameters allows data fusion techniques to provide situation awareness to its users. Taking advantage of this real-time data, the routing methodologies and data capture techniques studied in this paper provides Emergency Medical Services with better routes when responding to a vehicular crash. Comparing the performance of both routing methodologies in terms of both their ability to provide better routes as well as computation times demonstrates two alternatives for aiding in future emergency response. 相似文献
18.
Advanced transportation sensors use a wireless medium to communicate and use data fusion techniques to provide complete information. Large-scale use of intelligent transportation sensors can lead to data bottlenecks in an ad-hoc wireless sensor network, which needs to be reliable and should provide a framework to sensors that constantly join and leave the network. A possible solution is to use public transportation vehicles as data fusion nodes or cluster heads. This paper presents a mathematical programming approach to use public transportation vehicles as cluster heads. The mathematical programming solution seeks to maximize benefit achieved by covering both mobile and stationary sensors, while considering cost/penalty associated with changing cluster head locations. A simulation is developed to capture realistic considerations of a transportation network. This simulation is used to validate the solution provided by the mathematical model. 相似文献
19.
MacLeod JK Flanigan IL Williams JF Collins JG 《Journal of mass spectrometry : JMS》2001,36(5):500-508
The (EIMS) electron ionization mass spectrometric fragmentation patterns of the methoxime- and ethoxime-trimethylsilyl (TMS) derivatives of C(4) to C(7) sugars involved as phosphates in the Calvin pathway of photosynthesis in plants were analysed by gas chromatography/EIMS using specifically labelled (13)C analogs. In general, most but not all of the major ions in the mass spectra arise from single carbon-carbon bond cleavages of the straight-chain derivatives. The results confirm that GC/MS of the alkoxime-TMS derivatives is a viable method for measuring (13)C incorporations at individual carbon atoms in each of the sugar phosphates during photosynthetic experiments with (13)CO(2). 相似文献
20.
Loren?S?Scuro PU?Simioni DL?Grabriel Elzira?E?Saviani Luzia?V?Modolo Wirla?MSC?Tamashiro Ione?SalgadoEmail author 《BMC biochemistry》2004,5(1):5