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<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Hi-<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Were these Spin60 or Spin50 cells? If they were Spin60, it might be that the lamp timing on the ‘noisy’ machine is causing the light pulse to partially hit
the centerpiece wall. This is a machine-to-machine problem, consistent with what you are seeing. However, the telltale for the timing problem is increased noise in the scans, often at the top of the cell, not a wave. Consequently, I vote for the slit assembly
lifting (John’s suggestion).<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Tom<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif"">From:</span></b><span style="font-size:10.0pt;font-family:"Tahoma","sans-serif""> RASMB [mailto:rasmb-bounces@list.rasmb.org]
<b>On Behalf Of </b>John Philo<br>
<b>Sent:</b> Monday, October 19, 2015 5:00 PM<br>
<b>To:</b> 'David Hayes'; 'RASMB'<br>
<b>Subject:</b> Re: [RASMB] Strange AUC noise<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:6.0pt"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:blue">David, I will speculate that you have a problem with the slit assembly. You might see something like that if the foil on the bottom side
has come partially loose. Or perhaps there is some dirt or a burr causing the whole assembly to lift up at certain radial positions.<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:6.0pt"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:blue">I once had the foil come loose in a way that produced wild outlier scans, but only every once in while (a few per run). Intermittently
the foil would actually catch on something (probably the ring on top of the PMT) and fold completely back on itself.<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:6.0pt"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:blue">And by the way, you should remind your people to fill the cells
<u>much</u> more. You want the meniscus to be up near 5.9 cm, not at ~6.25 cm.<o:p></o:p></span></p>
<p class="MsoNormal" style="margin-bottom:6.0pt"><span style="font-size:10.0pt;font-family:"Arial","sans-serif";color:blue">John<o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif"">From:</span></b><span style="font-size:11.0pt;font-family:"Calibri","sans-serif""> RASMB [<a href="mailto:rasmb-bounces@list.rasmb.org">mailto:rasmb-bounces@list.rasmb.org</a>]
<b>On Behalf Of </b>David Hayes<br>
<b>Sent:</b> Monday, October 19, 2015 11:14 AM<br>
<b>To:</b> RASMB <<a href="mailto:rasmb@rasmb.org">rasmb@rasmb.org</a>><br>
<b>Subject:</b> [RASMB] Strange AUC noise<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black">Hi all,<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black">We had some strange AUC noise in a recent experiment. In the pictures below from SEDFIT, the first two runs produced data as in the picture NNBekman1
(the IT guys name our instruments and they pruposely mispelled Beckman as Bekman years ago). A strange noise pattern showed up in the scans that were produced on day one. Then the sample was loaded into a new cell and run again on the same centrifuge producing
the strange noise pattern in the picture called NNBekman1. the filled cell was taken and gently mixed and then run on another centrifuge Bekman17 and made a perfectly fine patter shown in picture Beckman17.<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black">We have seen the strange noise before on our NNBekman1 centrifuge, but this is the first time on NNBekman2.<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black">Has anyone seen noise like this? <o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black">Any theories on the cause of the noise?<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black">It certainly looks like an optical artifact of some kind, but the time dependence is hard to explain.<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black">Kind Regards,<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black">David Hayes<o:p></o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="background:white"><span style="font-family:"Helvetica","sans-serif";color:black"><o:p> </o:p></span></p>
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