<html><head><meta http-equiv="Content-Type" content="text/html charset=windows-1252"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;"><div>Hi John,</div>I used a sharpened dissecting needle and a metal straight edge. And, yes you need an additional capillary at the top to allow the air to transfer to equalize the pressure between the sectors. Good point. Standard synthetic boundary cp's have both capillaries.<div><br></div><div>Walter</div><div>p.s. I don't think diamond tipped pens are very expensive.</div><div>You can get a carbide tipped pen (just as good on epon) from Sigma for $15.60 Cat # Z225568-1EA</div><div><a href="http://www.sigmaaldrich.com/catalog/product/aldrich/z225568?lang=en®ion=US">http://www.sigmaaldrich.com/catalog/product/aldrich/z225568?lang=en®ion=US</a></div><div><br></div><div><br><div><div>On Dec 18, 2014, at 13:22, John Sumida <<a href="mailto:jpsumida@u.washington.edu">jpsumida@u.washington.edu</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"><meta name="Generator" content="Microsoft Word 14 (filtered medium)"><style><!--
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</o:shapelayout></xml><![endif]--><div lang="EN-US" link="blue" vlink="purple"><div class="WordSection1"><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New";color:blue">Walter,<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New";color:blue"> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New";color:blue">Thanks. What would you use to cut/scribe the channel. I see that someone on RASMB used a diamond point pen – which sounds expensive. Could one use an exacto blade?<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New";color:blue"> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New";color:blue">I assume one would also want to cut a straight capillary channel somewhere near the top of the channel to equalize pressure?<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New";color:blue"> </span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New";color:blue">John S.<o:p></o:p></span></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New";color:blue"> </span></p><div><div style="border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in"><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""> Walter Stafford [<a href="mailto:wstafford3@walterstafford.com">mailto:wstafford3@walterstafford.com</a>] <br><b>Sent:</b> Thursday, December 18, 2014 9:57 AM<br><b>To:</b> John Sumida<br><b>Cc:</b> <a href="mailto:rasmb@rasmb.org">rasmb@rasmb.org</a><br><b>Subject:</b> Re: [RASMB] Centerpiece question<o:p></o:p></span></p></div></div><p class="MsoNormal"><o:p> </o:p></p><p class="MsoNormal">Hi John,<o:p></o:p></p><div><p class="MsoNormal"><span class="apple-tab-span"> </span>The synthetic boundary centerpieces generally work OK. A potential problem is that some protein may transfer from the solution side to the reference either by diffusion or by sedimentation (i.e. if the capillary is slightly "downhill" from the samples side to the reference side.)<o:p></o:p></p></div><div><p class="MsoNormal"><o:p> </o:p></p></div><div><p class="MsoNormal">The MM centerpieces were designed to avoid that potential problem. If you want to make your own MM centerpieces, you can scribe a capillary on the center rib with a deliberate "uphill" slant to avoid mixxing - this must be done very carefully under a dissecting microscope with a sharp, pointy object and must not be "too" deep, etc, etc... And no caffeine ...<o:p></o:p></p></div><div><p class="MsoNormal"><o:p> </o:p></p></div><div><p class="MsoNormal">Good luck,<o:p></o:p></p></div><div><p class="MsoNormal">Walter<o:p></o:p></p></div><div><p class="MsoNormal"><o:p> </o:p></p></div><div><p class="MsoNormal"><o:p> </o:p></p><div><div><p class="MsoNormal">On Dec 18, 2014, at 12:44, John Sumida <<a href="mailto:jpsumida@u.washington.edu">jpsumida@u.washington.edu</a>> wrote:<o:p></o:p></p></div><p class="MsoNormal"><br><br><o:p></o:p></p><div><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New"">Dear RASMB,</span><o:p></o:p></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New""> </span><o:p></o:p></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New"">For interference measurements where matching the sample and reference channel menisci is essential, is there a preference for either the meniscus matching centerpiece versus synthetic boundary centerpiece. We would be interested to hear about pros and cons.</span><o:p></o:p></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New""> </span><o:p></o:p></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New"">Thank you and happy holidays.</span><o:p></o:p></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New""> </span><o:p></o:p></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New"">Best regards,</span><o:p></o:p></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New""> </span><o:p></o:p></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New"">John Sumida, Ph.D.</span><o:p></o:p></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New""><a href="http://depts.washington.edu/cidb4bio/index.shtml"><span style="color:windowtext">Analytical Biopharmacy Core Facility</span></a></span><o:p></o:p></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New"">University of Washington</span><o:p></o:p></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New""><a href="http://www.moles.washington.edu/"><span style="color:windowtext">Molecular Engineering & Sciences Institute, G22</span></a></span><o:p></o:p></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New"">3946 West Stevens Way NE</span><o:p></o:p></p><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Courier New"">Seattle WA 98195-1653</span><o:p></o:p></p><p class="MsoNormal" style="text-autospace:none"> <o:p></o:p></p></div><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Times New Roman","serif"">_______________________________________________<br>RASMB mailing list<br><a href="mailto:RASMB@list.rasmb.org">RASMB@list.rasmb.org</a><br><a href="http://list.rasmb.org/listinfo.cgi/rasmb-rasmb.org">http://list.rasmb.org/listinfo.cgi/rasmb-rasmb.org</a><o:p></o:p></span></p></div><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Times New Roman","serif""> </span></p><div><p class="MsoNormal"><span style="font-size: 12pt; font-family: Arial, sans-serif;"><br><span class="apple-style-span">Walter Stafford</span><br><span class="apple-style-span"><a href="mailto:wstafford3@walterstafford.com">wstafford3@walterstafford.com</a></span><br><br><span class="apple-style-span">"We're all better off when we're all better off" –Eric Liu</span></span><span style="font-size:12.0pt;font-family:"Times New Roman","serif""> <o:p></o:p></span></p></div><p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Times New Roman","serif""> </span></p></div></div></div></blockquote></div><br><div apple-content-edited="true">
<span class="Apple-style-span" style="border-collapse: separate; border-spacing: 0px;"><br class="Apple-interchange-newline">Walter Stafford<br><a href="mailto:wstafford3@walterstafford.com">wstafford3@walterstafford.com</a><br><br>"We're all better off when we're all better off" –Eric Liu</span>
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