12,958 research outputs found
Integrated Parylene LC-ESI on a Chip
Full text linkIn this thesis, several microfluidic devices will be introduced to demonstrate the integration capability of a multilayer parylene surface micromachining technology. Due to its flexibility and versatility, various devices have been developed and integrated onto a single ship. Based on the technology, on-chip LC-ESI was successfully demonstrated.
Based on the technology, an electrostatically actuated micro peristaltic pump has been developed. An AC actuation voltage combined with a peristaltic actuation was used to demonstrate fluid pumping. A reasonable flow rate and pumping pressure were achieved. The pump dynamics and performance were then addressed further by an analysis based on a lumped-parameter model of the system.
Based on the same technology, an entirely surface micromachined electrostatically actuated valve has been demonstrated. A thermal flow sensor was integrated with the valve to be used for feedback control. Two modes, actuation voltage adjustment and PWM were investigated in characterizing the valve to control air flow. The testing results show that PWM has better linearity and performance.
Three types of capacitive fluidic sensors were demonstrated in several microfluidic applications. These include sensors for fluid pressure, flow rate, volume, and composition measurement. The sensors showed great promise for microfluidic applications because of their high sensitivity and easy integration capabilities. The integration of these sensors with abovementioned devices was achieved.
A novel electrochemical pumping system for on-chip LC gradient generation was demonstrated. This pump was able to deliver significant flow rates under high back pressures that are sufficient for many LC applications. On-chip gradient formation with integrated electrospray ionization was demonstrated.
Finally, a complete LC-ESI system was integrated in a chip format. Typical nano-LC reversed-phase gradient elution was demonstrated using on-chip electrolysis pump. Separated analytes from on-chip column were then sprayed into MS for analysis through an integrated ESI-nozzle. Separation results are comparable to those of commercial system. Peptide identification performance using the LC-ESI chip with MS was also very close to those achieved by the commercial system.</p
LC compensators for power factor correction of nonlinear loads
No full textThis material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. Copyright @ 2004 IEEEA method is presented for finding the optimum fixed LC compensator for power factor correction of nonlinear loads where both source voltage and load current harmonics are present. The LC combination is selected because pure capacitive capacitors alone would not sufficiently correct the power factor. Optimization minimizes the transmission loss, maximizes the power factor, and maximizes the efficiency. The performance of the obtained compensator is discussed by means of numerical examples
LC mask
No full textLC mask generated from Cam-CAN participants. Access Cam-CAN dataset here https://www.cam-can.org/index.php?content=dataset. Details of mask found here:
Liu, K. Y., Acosta-Cabronero, J., Cardenas-Blanco, A., Loane, C., Berry, A. J., Betts, M. J., … Hämmerer, D. (2018). In vivo visualization of age-related differences in the locus coeruleus. Neurobiology of Aging, 74, 101–111.
https://doi.org/10.1016/j.neurobiolaging.2018.10.01
LC mask
No full textLC mask generated from Cam-CAN participants. Access Cam-CAN dataset here https://www.cam-can.org/index.php?content=dataset. Details of mask found here:
Liu, K. Y., Acosta-Cabronero, J., Cardenas-Blanco, A., Loane, C., Berry, A. J., Betts, M. J., … Hämmerer, D. (2018). In vivo visualization of age-related differences in the locus coeruleus. Neurobiology of Aging, 74, 101–111.
https://doi.org/10.1016/j.neurobiolaging.2018.10.01
LC mask
No full textLC mask generated from Cam-CAN participants. Access Cam-CAN dataset here https://www.cam-can.org/index.php?content=dataset. Details of mask found here:
Liu, K. Y., Acosta-Cabronero, J., Cardenas-Blanco, A., Loane, C., Berry, A. J., Betts, M. J., … Hämmerer, D. (2018). In vivo visualization of age-related differences in the locus coeruleus. Neurobiology of Aging, 74, 101–111.
https://doi.org/10.1016/j.neurobiolaging.2018.10.01
LC compensators based on transmission loss minimization for nonlinear loads
No full textThis material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. Copyright @ 2004 IEEEThis paper presents a method employing the penalty function search algorithm to determine the LC compensator value for the optimal power factor correction in nonsinusoidal systems. The objective of the proposed method is to minimize the transmission loss while the power factor and efficiency are taken as constraints and utilized in order to solve the multiobjective optimization problem by transforming it into a single objective one. Examples show that the load nonlinearity can have a significant impact on optimal compensator sizes
LC-API/MS in Drug Metabolism and Pharmacokinetic Studies
No full textThe use of API interfaces with quadrupole mass spectrometers has been shown to give rise to good sensitivity, selectivity, and robustness for the interfacing of LC to MS. Since their introduction in the 1990s the technique has rapidly become widespread, but at the outset of this research programme, there were still a number of problems associated with it, particularly when dealing with complex sample matrices. The aim of this research programme was to study illustrative examples of the kinds of problems associated with the analysis of biological samples using LC-API-MS in an attempt to arrive at strategies which could be employed to eliminate, or at least compensate for, the problems.
Commonly reported problems include the occurrence of matrix effects - a change in response of the target analyte(s) as a result of the presence in the samples of co /late eluting interferences. An investigation which compared ESI with APCI ionisation illustrated a significant drawback in the accepted methodology for the elimination of matrix effects.
Optimal LC conditions for a number of assays may use non-MS-friendly mobile phases. A simple and convenient solution to this problem was found to be the post column addition of organic modifier, which reproducibly and reliably enhanced sensitivity. This approach was initially used for a range of dihydropyridine calcium channel blockers and was subsequently applied to a range of chiral compounds from different therapeutic groups to illustrate that this was applicable as a generic technique for increasing sensitivity (typically by around an order of magnitude) in low organic mobile phases.
Strategies to develop and validate methods for the determination of endogenous analytes in a biological fluid were investigated. This involved the use of a surrogate matrix, to develop a method for the determination of endogenous testosterone in human serum and the use of non-matrix calibration standards for the successful development and validation of a method for the analysis of indolyl 3 acryloylglycine (IAG) in human urine.
As a result of observations suggesting promotion of ionisation of deltamethrin in liver tissue sample extracts, it was postulated that this was due to the presence of high concentrations of surfactants. After confirming the effect, a series of systematic investigations were performed to attempt to understand the mechanism to be able to utilise this as a general method for the enhancement of signal with low sensitivity analytes. It was found that the type of surfactant and concentration used was directly associated with an increased (or decreased) response.
Although there remain a number of problems associated with the use of LC-API-MS, the work undertaken for this thesis has successfully demonstrated a number of techniques that can be applied to overcome these problems. Knowledge of the nature of the sample undergoing analysis, the required analytical conditions, and where required careful application of one of the techniques described will ensure that a robust method can be readily developed
Flow chart of ICPL-peptide labeling- LC-MALDI and ICPL-protein labeling-LC-MALDI.
No full textFlow chart of ICPL-peptide labeling- LC-MALDI and ICPL-protein labeling-LC-MALDI.</p
Cost-effective applications of power factor correction for nonlinear loads
No full textThis material is posted here with permission of the IEEE. Such permission of the IEEE does not in any way imply IEEE endorsement of any of Brunel University's products or services. Internal or personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution must be obtained from the IEEE by writing to [email protected]. Copyright @ 2005 IEEEThe objective of this paper is to propose a new approach for designing passive LC compensators by using the penalty function method as an optimization tool. The performance of the cost-effective passive LC compensator for a constant load depends on the appropriate inductor and capacitor selection. Several design methods are reviewed and a novel design methodology is proposed in this paper. By using the proposed method, the designer can quickly find appropriate parameter values to meet the desired circuit performance. Simulated results show that an appropriate combination of the inductor and capacitor selected by the proposed method can meet the desired power-quality requirement. Different cases of design examples are shown in this paper to verify the performance of the proposed design methodology
Synthesis of 3-chloro-3-methyl-d3-diazirine
No full textPT: J; CR: BURKHOLDER CD, 1980, J AM CHEM SOC, V102, P2847 GRAHAM WH, 1965, J AM CHEM SOC, V87, P4396 LIU MTH, 1974, CHEM ENG NEWS 0909, P3 ROBERTSON LC, 1972, J MOL SPECTROSC, V42, P403; NR: 4; TC: 2; J9: J ORG CHEM; PG: 1; GA: KN056Source type: Electronic(1
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