Analytical Chemistry Chemical Cytometry Quantitates Superoxide

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Figure 1. Scheme of the operation of the used solenoid micropumps in (A) activation (aspiration) and (B) deactivation (expulsion). Elements: 1, pretension spring; 2, solenoid; 3, spring; 4, inlet check valve; 5, outlet check valve; 6, metal core of solenoid; 7, membrane; 8, inner volume of pump; 9, inlet; 10, outlet. P/N090SP-12-8, P/N110TP-12-40, and P/N120SP-12-25) and are denoted as pumps 1, 4, 2, and 3, respectively. In the activation state, the SMP operate in suction whereas at deactivation the pulse volume is expelled in the forward direction by the pressure exposed by a metal spring as shown schematically in Figure 1. The product specifications indicate a pressure height of 1.3 m for aspiration and 3.5 m for dispensing. Detailed specifications cited in this article can be downloaded at the producer’s Web site. 11 For control and powering, an eight channel relay card (SERDIO8R) from EasyDAC (Glasgow, United Kingdom) was used. It allowed remote and independent control of up to eight solenoids (SMP or valves) via an RS232 serial interface. Connection of the solenoid and powering is accomplished via screw terminals, and no further equipment was required for operation. For reliable operation, parallel connection of a diode to the connected solenoid devices in reverse direction is required to deduct the induced counter-voltage at the solenoid release. The relay card is highly appropriate for miniaturization of MPFS as the dimensions are about 11 cm × 10 cm × 3 cm. A thorough description can be downloaded from the manufacture’s Web site. Three PTFE tubes of different lengths (L) and inner diameters (i.d.) were used as model flow resistances (tube 1, 49 cm, 0.2 mm i.d.; tube 2, 30 cm, 0.5 mm i.d.; and tube 3, 175 cm, 0.8 mm i.d.). For calibration of the effective pressure at a given flow rate, a Bu4S syringe pump module 12,13 (16.000 steps, 24-1024 s for total dispense) from Crison Instruments S.A. (Alella, Barcelona, Spain) was used, equipped with a glass syringe of 5 mL from Hamilton Bonaduz AG (Bonaduz, Switzerland). Pressure measurements were performed using a Bourdon pressure gauge of 6 bar working range connected by a peek tube (20 cm, 0.8 mm i.d.) and a three-way connector between the solenoid pump and the pressure resistance. 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. (11) http://www.biochemfluidics.com/pdf/micro-pumps_brochure_dn_ibpmp- 01_r1.pdf, accessed February 20, 2010. (12) Cerda, V.; Estela, J. M.; Forteza, R.; Cladera, A.; Becerra, E.; Altimira, P.; Sitjar, P. Talanta 1999, 50, 695–705. (13) Horstkotte, B.; Elsholz, O.; Cerdá, V. J. Flow Injection Anal. 2005, 22, 99–109. 6984 Analytical Chemistry, Vol. 82, No. 16, August 15, 2010 Remote software control of the relay card as well as of the syringe pump was done via an RS232C serial interface using the AutoAnalysis 5.0 platform 14 from Sciware (Palma de Mallorca, Spain) including specific dynamic link libraries (DLL) for each communication port and connected instrument. The DLL made for the used relay card was adapted for both SMP and three-way solenoid valves. It included a calibration mode for connected SMP, definition of the mean pulse volume and minimal activation time for each relay, and the selection and definition of two of the three operation parameters (flow rate, dispense volume, and operation time) for each step and for each individual SMP. The control panels corresponding to configuration and operation instructions are shown in Figure 2, respectively. The DLL is commercially available from Sciware SL. RESULTS AND DISCUSSION Calibration of the Flow Resistances. For calibration of flow resistances, a smooth, nonpulsed flow was required. Therefore, a syringe pump was used. The obtained data are given in Table 1. The relation between flow rate and pressure was linear, and effective flow resistances of 0.66, 0.062, and 0.017 bar min mL -1 were found corresponding to hydrodynamic diameters of tubes of 0.27, 0.42, and 0.91 mm i.d. 3.2. Calibration of the Solenoid Micropumps. For calibration, the volume of water resulting from 240 pump pulses was weighted in triplicate using an activation frequency of 2 Hz and, for both the in- and outflow of the SMP, PTFE tubes of 20 cm length and 1.5 mm i.d., respectively, which corresponded to neglectible flow resistances. The activation time was varied between 50 and 400 ms. Longer activation times were not feasible due to low operation reliability and excessive heating of the solenoid. The results and mean pulse volumes are represented in Figure 3. It was found that the mean pulse volume was approximately stable for activation times between 150 and 300 ms and exceeded in every case the nominal volume given by the producer: by 12% (pump 1), 21% (pump 2), 40% (pump 2), and 120% (pump 4) (P/ (14) Becerra, E.; Cladera, A.; Cerda, V. Lab. Robotics Autom. 1999, 58, 131– 140.
Figure 2. Configuration editor window (above) and instruction command window (below) for the software control of the used relay card using the program AutoAnalysis. Table 1. Data from Calibration of Model Flow Resistances flow rate [mL/min] tube 1 (49 cm, 0.2 mm i.d.) pressure [bar] tube 2 (30 cm, 0.5 mm i.d.) tube 3 (175 cm, 0.8 mm i.d.) 0.50 0.30 0.60 0.35 0.75 0.47 1.00 0.70 1.50 1.00 2.50 0.15 3.75 0.22 5.00 0.32 0.08 6.00 0.40 0.10 7.50 0.50 0.14 pressure/flow rate 0.659 0.0651 0.0175 [bar min mL -1 ] hydrodynamic diameter [mm] 0.27 0.42 0.91 N110TP-12-40). For pumps 2 and 3 (type P/N120SP-12-25), the same behavior of decreasing pulse volume with increasing activation time was found, while for pumps 1 and 4, the expulsion volume increased with the activation time. This was reduced to different responses of the rubber two check valves (see Figure 1). Because of slight differences in fabrication and abrasion, the characteristics of the pump are assumed to be determined by the weaker check valve. For pump 4, activation times below 50 ms or above 400 ms disabled pumping operation. Activation times above 250 ms lead to notable pump heating, leading to higher pulse volumes. 3.3. Pressure Pulse Model 1. To simulate the pressure pulse, a numerical flow model was created. The inner volume of the SMP (see Figure 1) can be described best by a cone, where the base is the cross section area of the inner cavity of the pump and the surface shell is the membrane elevated in its central point by attraction of the solenoid. The inner volume is therefore calculated by eq 1, where h i is the lift of the membrane at time i. Vin,i ) 1 3 r 2 pump πhi (1) At the release of the solenoid, the pressure is equal to the spring force F applied on the inner cross section area A of the pump. The spring force is a product of the spring constant D and the sum of the initial lift h0 and the pretension h′ according eq 2. The initial lift was calculated from the calibrated pulse volume of the pump by transformation of eq 1. p 0 ) F spring A pump ) D(h0 + h′) ) 2 π r pump D( 3Vpump + h′) 2 rpump π 2 rpump π Analytical Chemistry, Vol. 82, No. 16, August 15, 2010 (2) 6985
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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
Page 189 and 190: Anal. Chem. 2010, 82, 6933-6939 Dif
Page 191 and 192: 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
Page 219 and 220: Figure 1. (A) ESI-LTQ-CID-MS 2 prod
Page 221 and 222: Figure 3. (A) ESI-LTQ-CID-MS 2 prod
Page 223 and 224: Figure 5. (A) MALDI-TOF/TOF product
Page 225 and 226: Anal. Chem. 2010, 82, 6969-6975 Ana
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
Page 235 and 236: allow the use of higher aptamer con
Page 237 and 238: quent ligation of the aptamers afte
Page 239: Anal. Chem. 2010, 82, 6983-6990 Imp
Page 243 and 244: Figure 4. Dependencies between volu
Page 245 and 246: Since the time for liquid expulsion
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
Page 259 and 260: (principal components, PCs) in whic
Page 261 and 262: Figure 5. Relevant score plots and
Page 263 and 264: CONCLUSIONS In this paper we have i
Page 265 and 266: electroactive-species loaded liposo
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
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Anal. Chem. 2010, 82, 7035-7043 Qua
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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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