Analytical Chemistry Chemical Cytometry Quantitates Superoxide

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ptube,i ) ∆V C ) Vi - V0 C Figure 5. Modeling of the pressure and flow pulse of pump 3 for the used flow resistances (A) tube 1 (49 cm, 0.27 mm i.d.), (B) tube 2 (30 cm, 0.42 mm i.d.), (C) tube 3 (175 cm, 0.91 mm i.d.) with no tube elasticity. 6988 Analytical Chemistry, Vol. 82, No. 16, August 15, 2010 (7) The two flow rates out of the pump into the elastic tube QIn and out of the elastic tube QOut through the flow resistance were defined. QOut was calculated from the pressure in the elastic tube and the connected flow resistance analogous to eq 3. QIn was calculated according eq 8 distinguishing three cases. (1) The SMP is already empty and consequently both ppump and QIn are zero. (2) The pressure in the tubing and the SMP are equal so that the QIn is equal to QOut. (3) The ppump overcomes ptube so that QIn is limited by the pressure difference and the flow resistance of the outlet check valve defined by its passage radius rValve and its length LValve according to eq 3 and its time response T and QOut. Qin,i ) ppump,i ) 0|) 0 {if ppump,i > ptube,i | ) (ppump,i - ptube,i )(1 - e t/T ) r } 4 Valve π + Qout,i 8ηLValve ppump,i ) ptube,i | ) Qtube,i (8) The accumulating volumes of expulsion from the SMP into the elastic tube VIn and from the compliance elastic tube through the flow resistance VOut were calculated according to eq 9. V i )Q i-1 ∆t + V i-1 The inner volume of the elastic tube was calculated by eq 10 being a simple balance of the initial volume, the flow out QOut, and the flow in QIn. (9) V tube,i )V tube,i-1 + Q In,i-1 ∆t - Q Out,i-1 ∆t (10) 3.6. Improvement of Pressure Resistance. Increasing the elasticity of the flow resistance connected to the SMP allows a fast flow out of the pulse volume. This decreases the pulsation character of the flow and leads to a stabilized but lower pressure in the system. Since the backpressure is proportional to the 2nd power of the flow rate, smoothing the flow pulsations by an integral element such as an elastic pumping tube could decrease the peak flow rate through the flow resistance and improve the OE. Table 2. Theoretical Pressure for the Tested Mean Flow Rates Using the Model Flow Resistances and Found Dynamic Inner Diameters flow rate [mL/min] tube 2 (0.27 mm i.d. 49 cm) pressure [bar] tube 2 (0.42 mm i.d. 30 cm) tube 3 (0.91 mm i.d. 175 cm) 0.2 0.13 0.3 0.19 0.02 0.01 0.5 0.31 0.03 0.01 0.8 0.50 0.05 0.01 1.0 0.63 0.07 0.02 1.5 0.94 0.10 0.03 2.0 1.25 0.13 0.03 3.0 1.88 0.20 0.05 5.0 0.33 0.09
Since the time for liquid expulsion increases with the pulse volume of the used pump, the contribution of any existing leakages through the inlet check valve of the SMP would increase as well. Allowing a fast flow-out against an apparently lower flow resistance can therefore increase the OE because after expulsion the resistance of two check valves would have to be overcome to enable a counter-directional flow. By this, the solenoid membrane can reach its final position of the deactivated status in less time and can aspirate a full pulse volume again. On the other hand, another producer of equivalent solenoid micropumps stated that “it is recommended to use hard tubing for piping” 16 since soft tubing might absorb the pressure pulse and affect the OE of the SMP. For testing the potential of pressure pulse dampers, two pieces of purple/black marked peristaltic pumping tube (2.05 mm i.d.) of 30 and 6.5 cm effective length were used and inserted between solenoid pump 4 and the model flow resistance tube 1. As shown in Figure 4D, the insertion of the shorter peristaltic pumping tube doubled the operation efficiency of the pump and a further improvement of 10% was possible using the longer peristaltic pumping tube. However, it was observed that the flow was delayed and lasted several seconds after finalization of the pumping operation. The compliance of the elastic tube, i.e., the volumetric expansions of the elastic tube in function of the inner pressure was an experimental parameter. It was measured by connecting the elastic tube and the former flow resistance tube 1 to the syringe pump and applying different flow rates. When the flow stops, the lasting flow out was collected and weighed. A linear relationship between pressure, calculated from the applied flow rates and resistance, and volume was found in the range of 0.3 to 1.2 bar, leading to a compliance of 1055 µL/bar per meter of the elastic tube. It was not possible to measure neither the response time of the check valve nor the flow path dimensions during the flow out. Values used for the flow model 2 were estimated to be 1 mm flow path length, 0.4 mm open diameter, and a delay time of 50 ms. The values have influence on the flow out velocity from the SMP into the elastic tube but little impact on the flowout through the flow resistance and would not affect the simulation of the contribution of the elastic tube of the OE of the SMP significantly. The simulation of four consecutive pressure pulses with a frequency of 0.33 Hz is shown in Figure 6 for neglecting any elasticity (A) and considering the 30 cm peristaltic pumping tube (B) for pump 4 and the flow resistance tube 1 applying time steps of 10 and 2 ms, respectively. It becomes clear that a single pressure pulse is insufficient to describe and explain why better OE was achieved using the elastic tube. However, under repeated operation and allowing a flow out after stopping the SMP operation renders higher OE values. Considering further a leakage through the inlet check valve or higher OE, the difference between both operation modes (with and without the elastic tube) would even become more pronounced. (16) http://www.takasago-elec.co.jp/en/product/pump.html, accessed February 20, 2010. Figure 6. Modeling of the pressure and flow pulse of pump 4 for the used flow resistances (A) without elasticity included and (B) with an elastic pumping tube of 30 cm estimating a delay time of 50 ms. Further study would be required to optimize the dimensions of peristaltic pumping tubes as a function of the pulsation volume. In fact, we did not achieve better but worse operation efficiencies for the other pumps using the elastic pumping tubes of the given dimensions. Model 2 still shows some shortcomings: the aspiration step of the SMP was not included, and the flow resistances, delay times, and leakage loss of the check valves were not quantifiable but were estimated. However, both presented models were suited to describe the observations of SMP operation and thus present the first reported intent of SMP simulation. CONCLUSIONS Time adaptation and the rational use of a new economic relay card for the improvement of the operation reliability of SMP was presented. The OE being the ratio of the calibrated pulse volume and the experimental one was studied with the dependence of the connected flow resistance and activation time over a wide range of operation frequency. For the first time, the operation of SMP was simulated by pressure pulse models. The following conclusions and recommendations for future works using SMP can be made: (1) Activation and deactivation times should both exceed 150 ms. (2) The pulse volume has to be calibrated in the flow system at the desired flow rate since flow resistance and operation frequency both affect the OE considerably. (3) The use of SMP of small pulse volume at higher frequency promises higher OE than lower operation frequency using SMP with a larger pulse volume. (4) The pressure robustness of SMP passed the charac- Analytical Chemistry, Vol. 82, No. 16, August 15, 2010 6989
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Anal. Chem. 2010, 82, 6745-6750 Let
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purchased from Invitrogen-Molecular
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Figure 3. Electropherograms of TPP-
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Anal. Chem. 2010, 82, 6751-6755 Res
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(pH 8.0) with cysteine and cystamin
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Figure 4. Ion mobility mass spectra
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GOx glucose + O298 gluconic acid +
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coater at 2000 rpm for 20 s, and th
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Figure 5. Comparison of cyclic volt
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in channels with either no grooves
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indicators of atmospheric processin
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Figure 1. GC/MS total ion chromatog
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Table 2. Concentrations and Stable
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on a substrate are preferred. 20-24
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Figure 4. SERS analysis of NAADP co
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Anal. Chem. 2010, 82, 6775-6781 Hig
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tion, 2 µL of proprionaldehyde wer
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Figure 4. Analysis of 2a by HPLC-MS
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eaction of 1a with PBH can be condu
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Numerous references had demonstrate
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Figure 1. TEM images of the prepare
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Figure 4. Schematic representation
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esult in a big SPR signal change wi
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also reduces chemical noise, which
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Table 1. Extraction Yields, Liquid
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scanning of AMPP amides of the anal
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Anal. Chem. 2010, 82, 6797-6806 δ
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Figure 1. Schematic view of the pre
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from the specimen and enclosed in a
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Figure 4. (A) IRMS mass-44 chromato
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Table 3. Ambient Measurement Result
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Anal. Chem. 2010, 82, 6807-6813 Dir
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Polymerase (1 U per sample). Reacti
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of which was constant for all ampli
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analytically useful signals at less
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carbon black and RP-C18 for the ext
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solution in an equal volume, and 1
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Table 2. Concentrations and Ratios
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Anal. Chem. 2010, 82, 6821-6829 Mac
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mg/mL protein, followed by separati
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Figure 2. Productivity of SEQUST an
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Figure 4. High-resolution MS/MS spe
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Figure 6. Characterization of PSMs
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containing T-T mismatches. 23 Based
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Figure 1. Extinction spectra of sol
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Figure 3. (A) The value of Ex650 nm
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Figure 5. Extinction spectra and co
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wished to explore the dehydration o
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constant medium for separation; we
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Figure 2. Standards of (Pi)n, n ) 1
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Figure 5. Quantitative calibration
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Anal. Chem. 2010, 82, 6847-6853 Met
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Figure 1. 226 Ra spectrum by liquid
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Table 1. Counting Properties and De
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Table 3. Analysis of 226 Ra in Sedi
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mercial microarray scanner and fabr
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Figure 2. Optical transmission meas
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Figure 5. Volcano plots detailing t
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data as well. The 41 genes in Table
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corresponding compound if its chemi
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Figure 1. Schematic illustration of
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Table 1. Absolute Quantification Re
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ment. Therefore, the long-time drea
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Figure 1. Chemically actuated micro
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Figure 2. Influence of a surfactant
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Figure 5. Device to eject and mix s
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Anal. Chem. 2010, 82, 6877-6886 Imm
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NaCl, phosphate buffer saline (PBS)
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Figure 2. Product ion mass spectra
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-70 °C resolved the problem, givin
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Table 1. Intraday Precision and Acc
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Anal. Chem. 2010, 82, 6887-6894 Fer
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Figure 1. Infrared spectra of (A) u
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Figure 3. Cyclic voltammograms obta
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Figure 6. Calculated charge from ch
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Anal. Chem. 2010, 82, 6895-6903 Ele
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Table 1. Chemical Structure, pKa Va
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pH with a tilted baseline (Figure 1
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Table 2. Linearity and Detection Li
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ascorbic acid (AA), uric acid (UA),
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the multielement capabilities, the
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RESULTS AND DISCUSSION Sulfur Detec
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Table 2. Molecular Properties and C
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Anal. Chem. 2010, 82, 6911-6918 Dir
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dilution and hybridization buffer.
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solution under appropriate incubati
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Figure 4. Standardization curve for
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Anal. Chem. 2010, 82, 6919-6925 Ele
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the ×10 objective, to have a large
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Figure 2. With a suitable removal o
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the NB signal in a much better foot
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Scheme 1. Reactions of Selenium Rea
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Figure 2. (a) ESI-MS spectrum showi
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Figure 4. (a) ESI-MS spectrum showi
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Anal. Chem. 2010, 82, 6933-6939 Dif
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trode 28 by a finite element using
Page 193 and 194: Figure 4. Comparison between simula
Page 195 and 196: Figure 6. Comparison between simula
Page 197 and 198: educed in the vicinity of double bo
Page 199 and 200: Figure 2. Normalized product ion ab
Page 201 and 202: Figure 4. EID (a) and IRMPD (b) of
Page 203 and 204: Anal. Chem. 2010, 82, 6947-6957 Ide
Page 205 and 206: Figure 1. Schematic flowchart showi
Page 207 and 208: difference, ppm compound Table 1. I
Page 209 and 210: isoforms, its successful use, in th
Page 211 and 212: Figure 5. Extracted ion current ESI
Page 213 and 214: m/z 1172.935 was observed for Ser14
Page 215 and 216: linked products via affinity tags.
Page 217 and 218: Scheme 2. Fragmentation Mechanism o
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Page 227 and 228: Figure 3. Equilibrium response as a
Page 229 and 230: Figure 6. The average measured resp
Page 231 and 232: for the fill time, and we find that
Page 233 and 234: nucleotide tails. 3-5 Thus, the amo
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Page 239 and 240: Anal. Chem. 2010, 82, 6983-6990 Imp
Page 241 and 242: Figure 2. Configuration editor wind
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Page 247 and 248: Anal. Chem. 2010, 82, 6991-6999 Int
Page 249 and 250: Figure 1. Representation of the Car
Page 251 and 252: Table 2. Capillary Electrophoresis
Page 253 and 254: Figure 4. (A) Typical raw electroph
Page 255 and 256: field. DNA profiles were delivered
Page 257 and 258: Another approach to handle this lim
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Page 261 and 262: Figure 5. Relevant score plots and
Page 263 and 264: CONCLUSIONS In this paper we have i
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Page 267 and 268: Figure 2. Qdot-based FLFTS response
Page 269 and 270: Figure 6. Fluorescence imaging of Q
Page 271 and 272: Anal. Chem. 2010, 82, 7015-7020 Sel
Page 273 and 274: Table 1. Effect of 1 D-LC Condition
Page 275 and 276: Figure 3. Peak-production rate vers
Page 277 and 278: Anal. Chem. 2010, 82, 7021-7026 Cel
Page 279 and 280: luciferase (T7 control vector) was
Page 281 and 282: Figure 3. Inhibitory effects of luc
Page 283 and 284: Anal. Chem. 2010, 82, 7027-7034 Pat
Page 285 and 286: Electrochemistry. Electrochemical m
Page 287 and 288: Figure 2. SEM images of Au substrat
Page 289 and 290: Table 3. Film Thickness Measurement
Page 291 and 292: Anal. Chem. 2010, 82, 7035-7043 Qua
Page 293 and 294: Figure 1. (A) FL spectra of BSPOTPE
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Figure 4. (A) Variation in the FL i
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Figure 6. (A) FL spectra of BSPOTPE
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Scheme 1. Proposed Mechanism for Fl
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one or more drawbacks including poo
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Figure 2. Free fluorophores do not
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Anal. Chem. 2010, 82, 7049-7052 Dev
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Figure 2. Comparative analysis of d
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