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	<title>DP Chemistry: Isotopes in teeth</title>
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  <meta name="description" content="It seems strange to me that in Topic 2.1.7 you will need to discuss the use of radioisotopes and yet the theory of radioactivity as such is not on the syllabus. The examples listed in the teacher’s notes in the guide on page 51 include carbon dating which, of course, is perhaps the best known of all the classic examples....">
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  <meta name="twitter:description" content="It seems strange to me that in Topic 2.1.7 you will need to discuss the use of radioisotopes and yet the theory of radioactivity as such is not on the syllabus. The examples listed in the teacher’s notes in the guide on page 51 include carbon dating which, of course, is perhaps the best known of all the classic examples....">
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href="../../page/18946/personal-engagement.html">Personal engagement</a></li><li><a href="../../page/18950/exploration.html">Exploration</a></li><li><a href="../../page/18957/analysis.html">Analysis</a></li><li><a href="../../page/18965/evaluation.html">Evaluation</a></li><li><a href="../../page/18966/communication.html">Communication</a></li><li><a href="../../page/19882/internal-standardization-of-the-ia.html">Internal standardization of the IA</a></li><li><a href="../../page/19901/submitting-the-samples-for-moderation.html">Submitting the samples for moderation</a></li><li><a href="../../page/33754/ten-suggestions-for-ias-using-secondary-data.html">Ten suggestions for IAs using secondary data</a></li><li><a href="../../page/37544/gaining-full-marks-for-a-databased-ia-.html">Gaining full marks for a databased IA </a></li><li><a href="../../page/19506/ia-example-marking-exercise-.html">IA example & marking exercise </a></li><li><a href="../../page/23929/genuine-examples-of-moderated-ia-reports.html">Genuine examples of moderated IA reports</a></li><li><a href="../../page/25234/examples-of-teacher-marked-ia-reports-.html">Examples of teacher-marked IA reports </a></li><li><a href="../../page/37542/history-of-internal-assessment.html">History of Internal Assessment</a></li></ul></li><li><a href="../../page/16598/mandatory-laboratory-components.html" class="father">Mandatory laboratory components</a><ul class="level-2"><li><a href="../../page/16613/formula-of-magnesium-oxide-.html">Formula of magnesium oxide </a></li><li><a href="../../page/16612/determining-the-mr-of-an-unknown-gas.html">Determining the <i>M</i><sub>r</sub> of an unknown gas</a></li><li><a href="../../page/16615/acid-base-titrations-.html">Acid-base titrations </a></li><li><a href="../../page/16616/a-green-acid-base-practical.html">A green acid-base practical</a></li><li><a href="../../page/16617/analysis-of-aspirin-tablets.html">Analysis of 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href="../../page/17168/other-good-practicals.html" class="father">Other good practicals</a><ul class="level-2"><li><a href="../../page/17196/common-chemical-reactions.html">Common chemical reactions</a></li><li><a href="../../page/227/elements-oxides-of-the-third-period-.html">Elements & oxides of the third period </a></li><li><a href="../../page/17239/the-halogens.html">The halogens</a></li><li><a href="../../page/17162/boiling-points-of-mixtures.html">Boiling points of mixtures</a></li><li><a href="../../page/17170/polarity-of-molecules.html">Polarity of molecules</a></li><li><a href="../../page/18083/le-chateliers-principle-.html">Le Chatelier&#039;s principle </a></li><li><a href="../../page/19582/determining-kc-for-an-esterification-reaction.html">Determining <i>K</i><sub>c</sub> for an esterification reaction</a></li><li><a href="../../page/18164/redox-reactions-of-vanadium-.html">Redox reactions of vanadium </a></li><li><a href="../../page/18351/chlorine-in-swimming-pools-.html">Chlorine in swimming pools </a></li><li><a href="../../page/18178/analysis-of-cuii-ions-in-solution-.html">Analysis of Cu(II) ions in solution </a></li><li><a href="../../page/18179/percentage-of-copper-in-brass.html">Percentage of copper in brass</a></li><li><a href="../../page/18356/electrolytic-cells-.html">Electrolytic cells </a></li><li><a href="../../page/18598/reactions-of-organic-compounds.html">Reactions of organic compounds</a></li><li><a href="../../page/18752/hydrolysis-of-halogenoalkanes.html">Hydrolysis of halogenoalkanes</a></li><li><a href="../../page/18784/preparation-of-13-dinitrobenzene-.html">Preparation of 1,3-dinitrobenzene </a></li><li><a href="../../page/19022/determination-of-an-organic-structure.html">Determination of an organic structure</a></li><li><a href="../../page/19887/preparation-of-nylon-66.html">Preparation of nylon 6,6</a></li><li><a href="../../page/19343/determination-of-vitamin-c-content-.html">Determination of vitamin C content </a></li><li><a href="../../page/19342/hydrolysis-of-starch-.html">Hydrolysis of starch </a></li><li><a href="../../page/19159/preparation-purification-of-aspirin-.html">Preparation & purification of aspirin </a></li></ul></li><li><a href="../../page/18851/ict-in-practical-work.html" class="father">ICT in practical work</a><ul class="level-2"><li><a href="../../page/18852/data-logging-.html">Data logging </a></li><li><a href="../../page/18853/software-for-graph-plotting-.html">Software for graph plotting </a></li><li><a href="../../page/18854/spreadsheets-for-data-processing-.html">Spreadsheets for data processing </a></li><li><a href="../../page/18855/databases.html">Databases</a></li><li><a href="../../page/18856/computer-modelling-simulations-.html">Computer modelling & simulations </a></li></ul></li><li><a href="../../page/16594/group-4-project.html" class="father">Group 4 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            <h1 class="section-title">Isotopes in teeth</h1>
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                Thursday 24 June 2010
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	<img alt="" class="left " height="300" src="../../../ib/chemistry/images/News%20articles/Queen%20Eadgyth%2C%20%28c910-946%29-1.jpg" title="Analysis of the strontium isotopes in teeth have shown that the remains buried in Magdeburg Cathedral, Germany do indeed belong to Queen Eadgyth, (c910-946). " width="125">It seems strange to me that in Topic 2.1.7 you will need to discuss the use of radioisotopes and yet the theory of radioactivity as such is not on the syllabus. The examples listed in the teacher&rsquo;s notes in the guide on page 51 include carbon dating which, of course, is perhaps the best known of all the classic examples. Carbon dating relies upon the fact that carbon dioxide in the air contains some <sup>14</sup>C. Living things are continually replenishing their carbon content through respiration so they contain a fixed ratio of <sup>14</sup>C to <sup>12</sup>C. Once death occurs the <sup>14</sup>C gradually breaks down and forms nitrogen by &beta;- emission:</p>
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	<br>
	Because the half-life of carbon-14 is 5730 years the ratio of &nbsp;<sup>14</sup>C to <sup>12</sup>C gradually decreases and from its measured value the time that has elapsed since death can be determined accurately up to a period of about 60000 years.</p>


<p>
	The age of rocks which are of course much older can be determined by other radioisotope dating. For example <sup>87</sup>Rb decays to <sup>87</sup>Sr with a half-life of 4.88 x 10<sup>10</sup> years (49 billion years).<br>
	&nbsp;</p>
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	<img alt="" class="noborder" height="44" src="../../../ib/chemistry/images/News%20articles/Sr%20dating%20equation.jpg" width="150"></p>
<p>
	So that different minerals containing strontium will have a different ratio of <sup>87</sup>Sr to <sup>86</sup>Sr depending on their age.</p>

<p>
	During the past twenty years archaeologists have used the <a href="http://www.springerlink.com/content/lhw62171r056h038/">analysis of isotopes of strontium in teeth</a>&nbsp;to look at migratory patterns of humans as the ratio of the isotopes vary according to temperature, altitude, distance from the sea and local geology. This is a nice contemporary example to illustrate topic 2.1.7. &nbsp;Strontium, a Group 2 element, is absorbed by the body through soils and through the food chain where it substitutes for calcium. Depending on its source the ratio of <sup>87</sup>Sr to <sup>86</sup>Sr varies. As the strontium is absorbed by the body it becomes fixed in tooth enamel as the person grows thus providing a permanent record of the environment that the person grew up in.</p>
<p>
	This &lsquo;geographical signature&rsquo; has <a href="http://news.bbc.co.uk/1/hi/england/bristol/10332975.stm">recently been used to prove</a> beyond reasonable doubt that bones found in Magdeburg Cathedral in Germany belonged to the Anglo-Saxon Princess Eadgyth. Eadgyth was the granddaughter of Alfred the Great and is known to have to have married Otto the son of Henry, King of Saxony which was part of the German empire in 929 AD. When Henry died in 936 AD Otto became king of Germany and Eadgyth ruled as his queen until she died in 946 AD. Analysis of the <sup>87</sup>Sr to <sup>86</sup>Sr ratio of the teeth found in her tomb in Magdeburg confirmed that she had indeed spent the early part of her childhood in southern England.</p></div>
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            <p class="search-tags"><strong>Tags: </strong><a href="../../search/isotopes.html">isotopes</a>, <a href="../../search/strontium.html">strontium</a>, <a href="../../search/carbon%20dating.html">carbon dating</a>, <a href="../../search/index.htm"></a></p>
            <div class="prevnext-posts"><div class="pull-right text-right"><a href="../../blog/3889/objective-3.html" style="font-style: normal">Objective 3? <i class="fa fa-chevron-circle-right"></i></a><br><em class="gray"><small>9 Aug 2010</small></em></div><div class="pull-left"><a href="../../blog/3327/chemistry-politics.html" style="font-style: normal"><i class="fa fa-chevron-circle-left"></i> Chemistry & politics</a><br><em class="gray"><small>19 Jun 2010</small></em></div></div>
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Please enable cookies to log in.</div><div class="alert alert-info"><i class="fa fa-question-circle"></i> Enabling cookies in <a target="_blank" style="margin: 0; padding: 0;" href="https://support.mozilla.org/en-US/kb/enable-and-disable-cookies-website-preferences">Firefox</a>, <a target="_blank" style="margin: 0; padding: 0;" href="https://support.google.com/accounts/answer/61416?hl=en">Chrome</a>, <a target="_blank" style="margin: 0; padding: 0;" href="http://windows.microsoft.com/en-us/windows-vista/block-or-allow-cookies">Explorer</a></div>';$("#modal-login .modal-header").append(msg)}if($(".panel-expandable > .panel-heading").click((function(e){e.preventDefault();var panel=$(this).closest(".panel-expandable"),expandables=panel.hasClass("panel-has-footer")?".panel-body, .panel-footer":".panel-body";panel.find(".panel-body").is(":visible")?(panel.find(expandables).slideUp("fast"),panel.find(".expander > .fa-minus").removeClass("fa-minus").addClass("fa-plus")):(panel.find(expandables).slideDown("fast"),panel.find(".expander > .fa-plus").removeClass("fa-plus").addClass("fa-minus"))})),$("#modal-find-out-more").css({width:.8*$("#container").width()+"px","margin-left":-.4*$("#container").width()+"px"}),$(".modal-xxl").length){var modalTopPos=Math.round(.07*$(window).height());$(window).width()>1200&&$(".modal-xxl").css({"max-width":$(window).width()>960?"960px":$(window).width()+"px",width:$(window).width()>960?"960px":$(window).width()+"px","margin-left":$(window).width()>960?"-480px":Math.round($(window).width()/2)}),$(".modal-xxl").css("top",modalTopPos+"px"),$(".modal-xxl").on("shown",(function(){var mHeaderH=$(this).find(".modal-header").outerHeight(),mBody=$(this).find(".modal-body"),mBodyH=mBody.outerHeight(),mFooterH=$(this).find(".modal-footer").outerHeight(),bottomOfTheModal=modalTopPos+mHeaderH+mBodyH+mFooterH;if(bottomOfTheModal<$(window).height())mBodyH+=$(window).height()-bottomOfTheModal-60,mBody.css("max-height",mBodyH+"px");else{$(window).scrollTop(0),modalTopPos=10,$(".modal-xxl").css("top",modalTopPos+"px"),bottomOfTheModal=modalTopPos+mHeaderH+mBodyH+mFooterH,availableScroll=bottomOfTheModal-$(window).height()+modalTopPos;var lastPos=-1;$(window).on("scroll",(function(){var s=$(window).scrollTop()>availableScroll?availableScroll:$(window).scrollTop();newPos=modalTopPos-s,newPos!=lastPos&&($(".modal-xxl").css("top",newPos+"px"),lastPos=newPos)}))}}))}function popupHelp(url,title,w,h){var dualScreenLeft=void 0!==window.screenLeft?window.screenLeft:screen.left,dualScreenTop=void 0!==window.screenTop?window.screenTop:screen.top,width,height,left=(window.innerWidth?window.innerWidth:document.documentElement.clientWidth?document.documentElement.clientWidth:screen.width)/2-w/2+dualScreenLeft,top=(window.innerHeight?window.innerHeight:document.documentElement.clientHeight?document.documentElement.clientHeight:screen.height)/2-h/2+dualScreenTop,newWindow=window.open(url,title,"menubar=no,location=no,resizable=0, width="+w+", height="+h+", top="+top+", left="+left);return window.focus&&(newWindow?newWindow.focus():$('<div class="alert alert-warning" style="margin-bottom: 0px;"><p class="help-block">Pop Up blocked. Please allow Pop Ups in your browser settings.</p></div>').insertBefore("body")),newWindow}if($(".open-student-access-help").click((function(e){e.preventDefault();var h=$(window).height()-20,w=$(window).width()<1280?$(window).width():1280;popupHelp(helpURL,"Student Access Help",w,h)})),$(".pop-up-help").click((function(e){e.preventDefault();var url=$(this).attr("href"),title=$(this).data("title"),h=$(window).height()-20,w;popupHelp(url,title,$(window).width()<1280?$(window).width():1280,h)})),$("section.tib-hiddenbox").length){var count=0;$($("section.tib-hiddenbox").get().reverse()).each((function(){var box=$(this),revealButton;$("<a />").attr("class","btn showhider").attr("rel","hiddenBoxContent"+count).attr("style","margin-bottom: 0;").html('<i class="fa fa-eye"></i>').insertBefore(box);var newContainer=$("<div />").attr("class","hidden-content").attr("id","hiddenBoxContent"+count).html(box.html());newContainer.hide(),newContainer.insertBefore(box),box.remove(),count++})),$("a.showhider").on("click",(function(e){var container=$("#"+$(this).attr("rel"));container.is(":hidden")?(container.fadeIn("fast"),$(this).html('<i class="fa fa-eye-slash"></i>')):(container.fadeOut("fast"),$(this).html('<i class="fa fa-eye"></i>'))}))}
			let commentEditor={};function initCommentsEditor(){const t=document.querySelector("#comment-content");t&&CKEDITOR.BasicEditor.create(t,{toolbar:{viewportTopOffset:50,items:["bold","italic","link","subscript","superscript"]},link:{decorators:{addLinkNoFollow:{mode:"automatic",callback:function(t){if(null!=t)return["http://","http://www","https://","https://www","ftp:"].some((o=>t.startsWith(o)))},attributes:{target:"_blank",class:"ck-link",rel:"nofollow"}}}}}).then((function(t){commentEditor=t,commentEditor.execute("heading",{value:"paragraph"})})).catch((function(t){console.error(t)}))}function replaceComment(content,commentId){$("#cancel-comment-post").trigger("click"),$("#comm-"+commentId+" > .comment-content div.comment-text").html(content)}function placeComment(html,fatherId){$("#comment-form").hide(),$("#comment-form textarea").val(""),fatherId>0?($("#comments #comm-"+fatherId).append(html),$("#comments").append($("#comment-form"))):$("#comments").append(html).append($("#comment-form")),$(".comment .fa-arrow-down").removeClass("fa-arrow-down").addClass("fa-reply"),$(".comment-content").removeClass("marked"),$("#comment-form").show("fast")}function update_sticky_comments(arrIds,mode){$.post("pages/edit/update-sticky-comments.php?mode="+mode,{ids:arrIds,ticket:$("#comment-ticket").val()},(function(data){1==data.success?("set"==data.mode&&$("#sticky-"+data.id).parents("div.comment").each((function(e){$(this).find("a.pull-right").first().addClass("sticky"),$(this).find("a.pull-right").first().attr("title","Unmark as important")})),"unset"==data.mode&&($("#sticky-"+data.id).removeClass("sticky"),$("#sticky-"+data.id).attr("title","Mark as important"),$("#sticky-"+data.id).closest("div.comment").find("div.comment").each((function(e){$(this).find("a.pull-right").first().removeClass("sticky"),$(this).find("a.pull-right").first().attr("title","Mark as important")})))):alert(data.error)}),"json")}"undefined"!=typeof CKEDITOR&&initCommentsEditor(),$("section#comments").on("click","#edit-comment",(function(e){e.preventDefault();var commentId=$("form#comment-form #comment-mode").val(),commentContent=commentEditor.getData(),ticket=$("#comment-ticket").val(),sectionId=$("#section-id").val();$.post("pages/comment.php",{action:"edit",comment_id:commentId,content:commentContent,ticket:ticket},(function(data){"0"==data.success?alert(data.error):replaceComment(data.text,commentId)}),"json")})),$("section#comments").on("click","a.edit-comment",(function(e){e.preventDefault(),$(".comment .hidden").removeClass("hidden");var commentId=$(this).data("comment-id"),form=$("form#comment-form"),text=$("#comm-"+commentId+" > .comment-content div.comment-text").html();commentEditor.setData(text),$("form#comment-form textarea").val(""),$("form#comment-form textarea").val(text),$("#comm-"+commentId+" > .comment-content > img").addClass("hidden"),$("#comm-"+commentId+" > .comment-content > div.comment-text").addClass("hidden"),$("#comm-"+commentId+" > .comment-footer").addClass("hidden"),$("#comm-"+commentId+" > .comment-content").append(form),$("form#comment-form #submit-comment").hide(),$("form#comment-form #edit-comment").show(),$("form#comment-form #cancel-comment-post").show(),$("form#comment-form #comment-mode").val(commentId),fancyScrollTo("comment-form"),$("form#comment-form textarea").focus()})),$("section#comments").on("click","#submit-comment",(function(e){e.preventDefault();var commentContent=commentEditor.getData(),fatherId=$("#father-comment").val(),ticket=$("#comment-ticket").val(),sectionId=$("#section-id").val();$.post("pages/comment.php",{action:"post",section_id:sectionId,father_id:fatherId,content:commentContent,ticket:ticket},(function(data){if("0"==data.success)alert(data.error);else{commentEditor.setData(""),placeComment(data.html,fatherId),$("form#comment-form #cancel-comment-post").hide();var n=0;$("#n-comments").text().length>0&&(n=parseInt($("#n-comments").text())),$("#n-comments").text(n+1)}}),"json")})),$("section#comments").on("click","a.reply-comment",(function(e){e.preventDefault(),$(".comment .fa-arrow-down").removeClass("fa-arrow-down").addClass("fa-reply"),$(".comment-content").removeClass("marked");var form=$("form#comment-form"),fatherId=$(this).parent().parent(".comment").attr("rel");form.find("#father-comment").val(fatherId),$(this).parent().parent(".comment").find("> .reply-area").append(form),$(this).find(".fa-reply").removeClass("fa-reply").addClass("fa-arrow-down"),$(this).parent().prev(".comment-content").addClass("marked"),$("form#comment-form #cancel-comment-post").show(),fancyScrollTo("comment-form"),$("form#comment-form textarea").focus()})),$("section#comments").on("click","#cancel-comment-post",(function(e){e.preventDefault(),$(".comment .hidden").removeClass("hidden"),$(".comment .fa-arrow-down").removeClass("fa-arrow-down").addClass("fa-reply"),$(".comment-content.marked").removeClass("marked"),commentEditor.setData("");var form=$("form#comment-form");$("section#comments").append(form),$("form#comment-form #father-comment").val("0"),$("form#comment-form textarea").val(""),$("form#comment-form #comment-mode").val("new"),$("#edit-comment").hide(),$(this).hide(),$("#submit-comment").show()})),$("section#comments").on("click","a.delete-comment",(function(e){var commentId=$(this).data("comment-id"),isFather=$("#comm-"+commentId).children(".comment").length>0,ticket=$("#comment-ticket").val(),msg="You are going to delete a comment.\n\nThis action cannot be undone.\n\nAre you sure?";isFather&&(msg="You are going to delete a comment and all its replies.\n\nThis action cannot be undone.\n\nAre you sure?"),confirm(msg)&&$.post("pages/comment.php",{action:"delete",comment_id:commentId,is_father:isFather,ticket:ticket},(function(data){if("0"==data.success)alert(data.error);else{$("#comm-"+commentId+".comment").replaceWith(data.text);var n=0;$("#n-comments").text().length&&(n=parseInt($("#n-comments").text())),$("#n-comments").text(n-parseInt(data.deleted))}}),"json"),e.preventDefault(),e.stopPropagation()})),$("section#comments").on("click","a.pull-right",(function(e){e.preventDefault();var arrayIds=[];$(this).hasClass("sticky")?(arrayIds.push($(this).closest("div.comment").attr("rel")),$(this).closest("div.comment").find("div.comment").each((function(e){arrayIds.push($(this).attr("rel"))})),update_sticky_comments(arrayIds,"unset")):($(this).parents("div.comment").each((function(e){arrayIds.push($(this).attr("rel"))})),update_sticky_comments(arrayIds,"set"))}));
$('.page-bookmarker').click(function(e){
	e.preventDefault();
	var pid = $(this).data('pid');
	var random = $(this).data('ticket');
	bookmarkPage(pid, random);
});

function bookmarkPage(pageId, random){
	$.get(
		'pages/bookmarks.php',
		{
			'id'		: pageId,
			'ticket'	: random
		},
		function(data){
			if(data['success'] == '1') {
				var buttonTitle = 'Favourite';
				if( $('.page-bookmarker').attr('title') == 'Favourite' ) {
					buttonTitle = 'Unfavourite';
				}
				
				$('.page-bookmarker > i').toggleClass('colored');

				$('.page-bookmarker.stacked > span').text(buttonTitle);
				$('.page-bookmarker').attr('title', buttonTitle);
			}
		},
		'json'
	);
}

// the comment icon becomes a popover
$('img.ico[src="/img/icons/comments.png"]').each(function(){
	var comment = $(this).attr('title');
	$(this).removeAttr('title');
	$(this).wrap('<a class="tib-popover" href="#" data-content="'+comment+'" data-togle="popover" data-placement="top" />');
});
$('img.ico[src="img/icons/comments.png"]').each(function(){
	var comment = $(this).attr('title');
	$(this).removeAttr('title');
	$(this).wrap('<a class="tib-popover" href="#" data-content="'+comment+'" data-togle="popover" data-placement="top" />');
});

$('.tib-popover').popover({
	html 		: true,
	trigger		: 'hover',
	delay		: {show: 300, hide: 300},
	placement	: function (context, source) {
		var position = $(source).position();
		if (position.top > 200)	 {  return "top";}
		if (position.left < 515) {	return "right"; }
		if (position.top < 200)	 {  return "bottom";}
		if (position.left > 515) {	return "left";	}
									return "top";
	}
}).click(function(e){
	e.preventDefault();
});

// LIVE CAROUSEL MANAGEMENT

// Miliseconds for the next slide
var carouselTime = 6500;

// Start carousels
$('div.carousel.slide').carousel({interval: carouselTime});

$('.tib-indicators > img').click(function(){
	// IN
	var index = $(this).index();
	var container = $(this).closest('.carousel.slide');
	container.carousel(index);
});
var hTopmenu = $('#topmenu').height();
var n = 0;
$('nav.top-nav > ul > li').each(function(k, e) {
    if (n > 1) {
        var diff = hTopmenu-(e.offsetTop+e.offsetHeight);
        $(e).find(' > ul ').css('margin-top', '-'+diff+'px');
    }
    n++;
});

		});
	</script>
</body>
</html>