1
Diamine-sulfuric acid reactions are a potent source of new particle formation
2
Coty N. Jen1*, Ryan Bachman2, Jun Zhao1,3, Peter H. McMurry1, David R. Hanson2
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Department of Mechanical Engineering, University of Minnesota – Twin Cities, 111 Church St. SE,
Minneapolis, MN, 55455, USA
2
Department of Chemistry, Augsburg College, 2211 Riverside Ave., Minneapolis, MN, 55454, USA
3
Institute of Earth Climate and Environment System, Sun Yat-sen University, 135 West Xingang Road,
Guangzhou 510275, China
1
*corresponding author email: jenxx006@umn.edu
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Supporting Information:
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S1) nB,max, nA,max, and np for TMEDA and Put
S2) Size distributions for particles formed from sulfuric + mono or diamines
S3) Power dependencies of Ntot on [A1]o and [B]
S4) Performance of AmPMS with acid scrubber
S5) Measurement of diamines in the atmosphere
S1) nB,max, nA,max, and np for TMEDA and Put
Figure S1 provides TMEDA and Put versions of Figure 2 from the main text. These two
diamines exhibit the same nB,max and nA,max trends as EDA whereby the particles are very acidic
at low [B]/[A1]o and require one diamine to form a stable particle. From this graph and Figure 2,
we conclude that diamines are more capable of stabilizing sulfuric acid clusters than
monoamines and are thus more potent nucleating agents.
[B]/[A1]o
0.01
0.1
1
nB,max,nA,max, or np
(molecules/particle)
9
[A1]o=2x10 cm
1000
0.01
0.1
1
-3
nA,max
nB,max
100
10
(a) TMEDA
(b) Put
1
1
10
1E8
23
24
25
26
27
100
1E9
1
10
1E8
100
1E9
[B] (top pptv, bottom cm-3)
Figure S1 TMEDA (a) and Put (b) plots of nA,max (filled symbol) and nB,max (open symbol) as a function of [B] (bottom x-axis,
given as pptv and cm-3). [A1]o was held constant at 2x109 cm-3. [B]/[A1]o is shown on the top x-axis. Red lines illustrate the
estimated number of molecules per particle, np, with the gray region showing the range of values corresponding to aqueous
sulfuric acid (higher) or solid DMA+sulfuric acid (lower).
28
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S1/11
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S2) Size distributions for particles formed from sulfuric + mono or diamines:
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Figure S2 illustrates how [A1]o alters the measured size distribution from 1.77 nm
mobility diameter and higher with [B] held constant at 4 pptv (±1 pptv) for the three diamines
and two monoamines. Particle size distributions were measured using a diethylene glycol SMPS
(DEG SMPS) with operating parameters described previously ADDIN EN.CITE [. The graph on
the left is at [A1]o=2x109 cm-3 and the right at 4x109 cm-3. As can be seen from the size
distributions, sulfuric acid+diamines produce more particles than with monoamines. Also, the
number mean diameter increases from ~2 nm to ~4 nm at double the [A1]o for all bases.
Interestingly, sulfuric acid+diamine particles exhibit slightly larger mean volumetric diameters
(3.0 and 5.2 nm) compared to DMA (2.8 nm and 5.1 nm) at both [A1]o. For both graphs,
[B]/[A1]o<1 and particles grow primarily by sulfuric acid uptake.
41
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48
The DEG SMPS did measure down to 1.34 nm; however, these data were omitted from
the total particle concentrations due to their high uncertainty from ion-induced clustering inside
the charger and its dependence on [A1]o and [B] [Jen et al., 2015]. Some fraction of the 1.34 nm
signal is due neutral particles and would primarily increase the total number of particles
measured for [A1]o<2e9 cm-3 if they were included in Ntot. Since this fraction is uncertain, Ntot
was calculated by integrating from 1.77 nm and including positive errors bars (factor of 5) on
Ntot at [A1]o<2e9 cm-3 (see Figure S4). More studies are needed to understand the neutral particle
contribution of the smallest sizes.
dN/dlnDp (cm-3)
(b)
(a)
1E+07
1E+06
1E+05
EDA
TMEDA
Put
DMA
MA
1E+04
1E+03
1E+02
1
10
1
10
Particle Mobility Diameter (nm)
49
50
Figure S2 Particle size distribution for [B]=4 pptv (9.6x107 cm-3) at two different [A1]o: (a) 2x109 cm-3 and (b) 4x109 cm-3.
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S3) Power dependencies of Ntot on [A1]o and [B]:
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58
Figure S3 illustrates how Ntot increases with [diamine] at various constant [A1]o. The
slopes of the linear regressions are given in the legends. These expressions apply only to the
experiments conducted in this particular flow reactor and serve as a tool to compare the
formation pathways between different chemical systems. At low [A1]o for all three diamines, the
slopes range from 0.4-1. As [A1]o increases, these slopes decrease due to higher particle
coagulation rates. Figure S4 shows Ntot as a function of [A1]o at various but constant [B] for the
three diamines. The open points signify high uncertainty in Ntot (factor of up to ~5) due to the
S2/11
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1.34 nm data (see section S2). Likely some fraction of 1.34 nm particles is real and if included
in Ntot, will decrease the calculated slopes. As a result, these points were omitted from the linear
regression. The slopes of the linear regression are given in the legends and range from 0.5-2 at
low [B]. Similar to high [A1]o, slopes tend to be lower at high [B]. We also attribute this to high
particle coagulation losses that limit Ntot. These two figures taken together suggest
2
N tot ~ [ A1 ]0.5
 [diamine]0.41 .
o
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Equation S1
This contrasts with the power dependencies described in Glasoe et al. [2015] where
Ntot ~ [ A1 ]o2.5  [DMA]2 .
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Equation S2
They hypothesized that the formation of a stable particle requires 2-3 sulfuric acids and 2 DMA
molecules, assuming the nucleation mechanism contains a single rate-limiting step [KupiainenMäättä et al., 2014]. The power dependencies for diamines suggest 1-2 sulfuric acids and 1
diamine molecule. This supports our conclusion from the main paper where nB,max for diamines
are independent of [B] at low [B]/[A1]o because only one diamine molecule is needed to form a
stable particle. Clearly, both amino groups in a diamine can interact with sulfuric acid
molecules, leading to clusters more stable than those formed from equal amounts monoamines.
Regardless of the number of bottle-necks, these power laws (Equations S1 and S2) show that
less [diamine] is required to form equivalent amounts of particles than [DMA] (and other
monoamines).
[EDA] (cm-3)
1E9
1E8
Ntot (cm-3)
1E8
[TMEDA] (cm-3)
[Put] (cm-3)
1E9
1E8
1E9
1E+07
[A1]o (cm-3) Slope
2E9
1.2 0.3
2.5E9
1.1 0.4
3E9
0.9 0.3
3.5E9
1.0 0.1
4E9
0.5 0.1
-3
[A1]o (cm ) Slope
2E9 0.64 0.06
3E9 0.53 0.06
4E9 0.35 0.05
1E+06
1
75
76
77
78
10
[EDA] (pptv)
100
1
10
[TMEDA] (pptv)
[A1]o (cm-3)
2E9
3E9
4E9
1
Slope
0.80 0.08
0.58 0.06
0.36 0.07
10
[Put] (pptv)
Figure S3 Ntot as a function of [diamine] for EDA (left), TMEDA (center), and Put (right). Each color in a panel represents a
constant [A1]o, and its corresponding line represents a linear regression at a constant [A1]o. The slopes and their standard
errors are given in the legends.
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EDA
Ntot (cm-3)
1E+08
TMEDA
Put
1E+07
[EDA] [EDA] (cm-3) Slope
(pptv)
1E+06
0.8
1
3
5
11
20
50
1E+05
1E9
80
81
82
83
84
85
86
87
88
89
90
91
92
93
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95
96
97
1.9E7
2.9E7
6.7E7
1.3E7
2.6E8
4.8E8
1.2E9
1.5
2.0
1.1
1.3
-0.1
0.6
-0.2
[Put] (pptv) [Put] (cm -3)
0.3
0.3


0.4
0.1
0.1
1E10
[TMEDA] (pptv) [TMEDA] (cm -3)
1
2
4
7
9
1E9
[A1]o (cm-3)
Slope
Slope
2.4E7
2.6 0.5
4.8E7
1.7 0.3
9.6E7 0.12 0.08
1.7E8 0.53 0.03
2.2E8 -0.1 0.3
1E10 1E9
1
4
8
12
2.4E7
9.6E7
1.9E8
2.9E8
1.9 0.3
1.2 0.1
0.8 0.2
0.47
1E10
Figure S4 Ntot as a function of [A1]o for EDA (left), TMEDA (center), and Put (right). Each color in a panel represents a constant
[B], and its corresponding line represents a linear regression at a constant [B]. The [B] are given in both pptv and cm -3. The
slopes of the regressions are given in the legends. The open points indicate high uncertainty in Ntot (see section S2 for
discussion).
S4) Performance of AmPMS measuring amines with acid scrubber
The atmospheric amine concentrations reported here represent the net signals at the specific
masses, determined by subtracting the background signals from total signal (see Freshour et al.
[2014]). Figure S5 provides mass scans with a dwell time of 0.5 s taken in Minneapolis, MN
during spring of 2014. Total signal is shown in the panel A as black bars and the background
signal is given as red outlined bars. The background signal was measured by sampling air
through a catalytic stripper. Panel B provides the net signal (total minus background) in green
outline. Diamine masses are highlighted as solid red bars and monoamines as solid blue bars.
The sharpness of the larger mass peaks (e.g. 80 amu and also larger mass peaks that are not
shown) demonstrates that the resolution is <1 amu; thus the diamine signals have little
interference from neighboring peaks.
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1E+05
(A)
Total Signal
Background Signal
Signal (Hz)
1E+04
1500
1000
500
0
20
30
40
50
60
70
80
90
100
110
120
Net Signal (Hz)
Mass (amu)
98
300
250
200
150
100
50
0
-50
(B)
20
Net signal
Diamines
Monoamines
30
40
50
60
70
Mass (amu)
80
90
100
110
120
99
100
101
102
Figure S5 (A) Sample mass scans from Minneapolis, MN during spring 2014 Black bars are the total signals and red outline is
the background signals. (B) Net signals were obtained by subtracting the background spectrum that was normalized by total
ion counts (except for 74 and 75 amu which were normalized to the 73 amu signal). The net diamines (red) and monoamines
(blue) are highlighted by solid bars.
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While not subject to interferences from neighboring peaks, the diamine signals may
include potential interferences from isobaric compounds. Given the odd mass number of the
protonated diamines, potential compounds would include oxygenated hydrocarbons (because of
mass similarities: N2 = CO and N2H2 = O2). These compounds need to exist in the single digit
ppb range or higher to significantly interfere with the diamine signals because AmPMS is very
insensitive to them [Hanson et al., 2011].
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120
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The fraction of the signals can be semi-quantified by adding an acid scrubber to remove
basic compounds onto the AmPMS inlet and was done after the SGP field campaign. The
scrubber consists of a 50 to 70 cm long perfluorocarbon tube treated with either liquid
phosphoric or sulfuric acid. Despite a lack of wettability, its efficiency for removal of basic gases
was high based on the behavior observed for ammonia and amines [Freshour et al., 2014].
Figure S6 shows the measured AmPMS mixing ratios (assuming maximum sensitivity) for
masses 59, 101, 60, and 169 amu from outdoor air sampled on April 2, 2014 in Minneapolis,
MN. Mass 60 amu is TMA and is known to be detected at maximum efficiency; the other masses
are compounds of unknown sensitivity: 169 amu could be monoterpene oxidation products (see
Sellegri et al. [2005]), 101 amu could be hexanone or hexenol, and 59 amu could be acetone
(detected at 1/300 efficiency). The gray regions indicate the periods when the scrubber was on
the inlet. Only the TMA signal dropped to background levels during the acid scrubs; the other
signals remains relatively constant. The scrubber may remove non-basic compounds from the
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sample stream, but as Figure S6 indicates, this likely occurs to a lesser extent than the targeted
bases.
35
59 amu
101
60 (TMA)
169
30
Signal (Hz)
25
20
15
10
5
0
11:00
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127
128
129
130
131
132
133
134
135
136
137
138
139
140
13:00
15:00
17:00
19:00
Time of Day (April 2, 2014)
Figure S6 Time series plot illustrating the acid scrubber performance during measurement of air from Minneapolis, MN
(2014). The 0.5 s mixing ratio data were average over 10 points. The shaded gray regions are when the acid scrubber was on
the AmPMS inlet and the pink regions show the time periods of instrument zeroes. Each line color represents a different
mass with 60 amu equivalent to trimethylamine. 59 amu is likely acetone, which is detected ~300 times less efficient than
amines. 169 amu represents monoterpene oxidation products as identified by Sellegri et al. [2005].
Table S1 lists the average fractional amounts of various diamine signals that were
removed by the acid scrubber, i.e. fraction of signal due to a diamine. Signals for Put and Cad
exhibit very high fractions (0.75), indicating that their signals are predominately the diamines.
About 50% of the signal for EDA is likely due to the diamine, with possible interference from
urea (61 amu). Note that net signals at the diamine masses were very low in Minneapolis with
average abundances just a few pptv; abundances in Atlanta and Oklahoma were much higher.
Also, air mass sampled in Minneapolis probably has a different mixture of compounds and
temporal dependence than the air at SGP, Lewes, or Atlanta. Thus, the fractions listed in Table
S1 were not applied to the field data, and the reported abundances represent the upper limit of
diamine concentrations found at these field sites.
Table S1 Summary of diamine signal from a dozen acid scrubber experiments in Minneapolis, spring 2014
Diamine, abbrev.
Mass, amu
Ethylenediamine, EDA
Propanediamine, PDA
Putrescine, Put
Cadaverine, Cad
Hexanediamine, HDA
60
74
88
102
116
Diamine fraction
of signal
0.45
No signal
0.75
0.75
0.34
Average abundance
(pptv)
1.0
0
1.3
5.9
3.9
141
142
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S5) Measurement of diamines in the atmosphere:
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147
148
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150
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152
153
154
155
156
The operation and signal averaging technique used for the AmPMS have been described
previously [Freshour et al., 2014]. The AmPMS measured several monoamines and diamines.
Figures S7-S9 show the measured concentrations of DMA, EDA, PDA, Put, Cad, and HDA for
the SGP, Lewes, and Atlanta field campaigns, respectively. [DMA] and other monoamine
abundances have previously been reported [Freshour et al., 2014; Hanson et al., 2011]. The
DMA abundances during the Lewes campaign exhibited large background signals during the
periodic instrument zeroes. As a result, the net signals for DMA were time averaged over an 8
hour period [Freshour et al., 2014]. The Cluster Chemical Ionization Mass Spectrometer
(Cluster CIMS) [Zhao et al., 2010] measured the sulfuric acid concentrations for each campaign
which are also shown. The Cluster CIMS also monitored sulfuric acid clusters (e.g. dimer,
trimer, and tetramer) but their abundances are not reported here because our previous laboratory
measurements of sulfuric acid-DMA clusters indicate that a potentially large fraction population
are not chemically ionized by nitrate [Jen et al., 2015].
S7/11
200
TMA
100
0
DMA
75
50
25
200
EDA
150
100
[B] (pptv)
50
80
PDA
60
40
20
300
Put
200
100
Cad
40
20
150
HDA
50
0
1E+07
Sulfuric acid
1E+06
1E+05
1E+04
Total Particle Conc
1E+04
1E+03
Temp
30
30
20
20
10
10
0
201
8/
4/1
157
158
159
160
161
162
0
3
Temp (C)
Total Particle
-3
Concentration (cm-3) [SulfuricAcid] (cm )
100
13
13
13
13
013
013
013
013
013
013
013
013
013
013
013
/20
/20
/20
/20
0/2
2/2
4/2
6/2
8/2
0/2
0/2
2/2
4/2
6/2
8/2
5/2
5/4
5/6
5/8
4/2
4/2
4/2
4/2
4/2
4/3
5/1
5/1
5/1
5/1
5/1
Date/Time
Figure S7 Measured upper limits for TMA, DMA, and various diamines during SGP field campaign of spring, 2013. The black
points are the sulfuric acid concentrations as measured by the Cluster CIMS. The purple line is the total particle
concentration measured by several particle SMPS with a lower range of 1.59 nm mobility diameter. The bottom panel shows
the temperature. The gray boxes indicate when certain instruments were non-operational. The vertical, solid black lines
signify the start of nucleation events.
S8/11
50
40
TMA
30
20
10
600
DMA
400
200
10
8
EDA
6
4
2
[B] (pptv)
30
PDA
20
10
10
8
Put
6
4
2
10
8
Cad
6
4
2
15
HDA
5
1E+08
Sulfuric acid
1E+06
1E+04
90000
90000
Total Particle Conc
60000
30000
30000
Temp (C)
60000
0
0
30
30
20
Total Particle
Concentration (cm-3)
[Sulfuric Acid] (cm-3)
10
20
Temp
10
10
012
012
012
012
012
012
012
012
012
012
012
012
012
012
012
012
4/2 /26/2 /28/2 /30/2 8/1/2 8/3/2 8/5/2 8/7/2 8/9/2 /11/2 /13/2 /15/2 /17/2 /19/2 /21/2 /23/2
7/2
7
7
7
8
8
8
8
8
8
8
163
164
165
166
167
168
Date/Time
Figure S8 Measured upper limits for TMA, DMA, and various diamines at Lewes, DE during summer, 2012. DMA exhibited large
backgrounds so the reported abundances are over 8 hour averages. The black points are the sulfuric acid concentrations measured by
the Cluster CIMS. The purple line is the total particle concentration measured by the butanol-based SMPS with a cutoff size of 3.1 nm
mobility diameter. The bottom panel shows the temperature. The gray boxes indicate when the Cluster CIMS was not operating. The
vertical, solid black lines signify the start of nucleation events and the dashed vertical lines are beginning of plume events.
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169
60
TMA
40
20
15
DMA
10
5
50
EDA
[B] (pptv)
25
100
80
60
40
20
PDA
200
150
Put
100
50
200
150
Cad
100
50
200
150
HDA
50
1E+09
1E+08
Sulfuric acid
1E+07
1E+06
1E+05
1E+04
8.0E4
Total Particle Concentration
6.0E4
4.0E4
2.0E4
0.0
Temp
Temp (C)
Total Particle
[Sulfuric acid] (cm-3)
Concentration (cm-3)
100
30
20
10
7 /2
1 /2
09
09
09
09
009
009
009
009
009
009
009
009
009
009
009
009
009
009
009
/20
/20
/20
/20
3/2
5 /2
7/2
9/2
1/2
0/2
2/2
4/2
6/2
8/2
0/2
2/2
4 /2
6/2
8/2
8/4
8/6
8 /8
7/2
7/2
7/2
7/2
7/3
8/1
8/1
8 /1
8/1
8 /1
8/2
8/2
8/2
8/2
Date/Time
170
171
172
173
174
175
Figure S9 Measured upper limits for TMA, DMA, and various diamines during Atlanta field campaign of summer, 2009. The black points
are the sulfuric acid concentrations as measured by the Cluster CIMS. The purple line is the total particle concentration measured by
the butanol-based SMPS with a cutoff size of 3.1 nm mobility diameter. The bottom panel shows the temperature. The gray boxes
indicate when the Cluster CIMS was not operating. The vertical, solid black lines signify the start of a nucleation event and the dashed
vertical lines are beginning of plume events.
S10/11
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Freshour, N., K. Carlson, Y. A. Melka, S. Hinz, and D. R. Hanson (2014), Quantifying Amine
Permeation Sources with Acid Neutralization: AmPMS Calibrations and Amines in Coastal and
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Glasoe, W. A., K. Volz, B. Panta, N. Freshour, R. Bachman, D. R. Hanson, P. H. McMurry, and
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185
186
Hanson, D. R., P. H. McMurry, J. Jiang, D. Tanner, and L. G. Huey (2011), Ambient Pressure
Proton Transfer Mass Spectrometry: Detection of Amines and Ammonia, Environmental Science
& Technology, 45(20), 8881-8888, doi:10.1021/es201819a.
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188
189
190
Jen, C. N., D. R. Hanson, and P. H. McMurry (2015), Towards Reconciling Measurements of
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Classification/Vapor Condensation, Aerosol Science and Technology, ARL, 49(1), i-iii,
doi:10.1080/02786826.2014.1002602.
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192
193
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Jiang, J., M. Chen, C. Kuang, M. Attoui, and P. H. McMurry (2011), Electrical Mobility
Spectrometer Using a Diethylene Glycol Condensation Particle Counter for Measurement of
Aerosol Size Distributions Down to 1 nm, Aerosol Science and Technology, 45(4), 510-521,
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Kupiainen-Määttä, O., T. Olenius, H. Korhonen, J. Malila, M. Dal Maso, K. Lehtinen, and H.
Vehkamäki (2014), Critical cluster size cannot in practice be determined by slope analysis in
atmospherically relevant applications, Journal of Aerosol Science, 77, 127-144,
doi:http://dx.doi.org/10.1016/j.jaerosci.2014.07.005.
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Sellegri, K., B. Umann, M. Hanke, and F. Arnold (2005), Deployment of a ground-based CIMS
apparatus for the detection of organic gases in the boreal forest during the QUEST campaign,
Atmos. Chem. Phys., 5(2), 357-372, doi:10.5194/acp-5-357-2005.
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mass spectrometric measurements of atmospheric neutral clusters using the cluster-CIMS, J.
Geophys. Res., 115(D8), D08205, doi:10.1029/2009jd012606.
References
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