Rotaxanes were developed by Fraser Stoddart in 1991, who subsequently won the 2016 Nobel Prize in Chemistry with Jean-Pierre Sauvage and Bernard L. Feringa for their work on molecular machines.

“[Sir Fraser] threaded a molecular ring onto a thin molecular axle and demonstrated that the ring was able to move along the axle. Among his developments based on rotaxanes are a molecular lift, a molecular muscle and a molecule-based computer chip.” (nobelprize.org)

The light source alters the chemistry of the orange terminal to impart a negative charge, represented by colour change to blue. The positively charged rotaxane is magnetically attracted to the negative charge and migrates along the shaft. When the terminal returns to its base state and loses its charge the rotaxane returns to its original position. 

This is happening at the molecular level!!

Chromatography is an exceptionally popular tool that is used every day in laboratories around the world for the analysis of chemical mixtures by the separation of unique chemicals through interactions between the molecules and the material that is permanently bonded to the chromatography column’s packing material.

Separation happens when chemicals have different strengths of interaction with the packing material as they are pushed through the chromatography column by a solvent, usually a mixture of water and a polar liquid chemical like methanol or acetonitrile.

When one chromatography column and solvent system is used there is a single type of chemical interaction that governs how strong these interactions are and the type of separation that is achieved. These include the chemical’s hydrophobicity (preference to be in a non-polar environment), polarity, shape, size, or other chemical properties. However, sometimes there are cases where a single type of interaction is insufficient to separate a complex chemical mixture and additional factors are required.

Multidimensional chromatography is an analytical tool takes advantage of two (or more) unique chemical properties to evoke separations in multiple dimensions. This provides the scientist with the potential of much more information about the nature of their samples through the distinction between chemical similar materials. There is also potential for multidimensional chromatography to separate a greater number of unique chemicals (as opposed to partial separation or coelution).

In the video below, the ‘chemical’ mixture consists of components of different shapes and colours. Before the separation all the chemicals are mixed together. The scientist wants to know how many chemicals there are and what is their shape and colour. When the plate is dipped in the first beaker the solvent mobile phase is selective to the shape of the chemical; the separation occurs based on shape to the exclusion of all other properties. This is analogous to a one-dimensional chromatographic separation. The plate is rotated and placed in the second dimension that is selective to the chemicals colour thereby completely separating these 5 chemicals that can now be identified and quantified.

Why is multidimensional chromatography important? Metabolomics is an example of current medical research that needs information rich analytical tools to take a snapshot of the chemical composition of a biological system. This can be used to find chemical markers that distinguish between health and disease/cancer state individuals. Untargeted experiments are commonly done by scientists to find these marker molecules and multidimensional techniques can give the researcher the needed analytical power. Mathematical and statistical analyses are then used to identify the key markers that inform on a patient’s medical state through modelling and predictive tools.

Header image credit Oliver Jones, RMIT University

Django CMS is a new toy for me and I’m very much enjoying exploring its capabilities! I wanted a blog on my website and I chose to use the ALDRYN NEWS & BLOG addon.

By default the look of the news & blog addon is, shall we say, minimalist – granted this is by design. This article is to help other newbies with little or know understanding how addons can be modified.

First of all, pip installs addons into the virtual environment. For my setup this is:

/home/foo/bar/lib/python2.7/site-packages/aldryn_newsblog/templates/aldryn_newsblog

where foo is the user directory and bar is the virtual environment. We are interested in the files inside the templates sub-directory – especially article.html, which is an includes.

I won’t go into the ins and outs of how this all works, but the detail flag is used by CMS to decide if the code is a preview or the full article:

{% load i18n staticfiles thumbnail cms_tags apphooks_config_tags %}
	<article class="article
	{% if article.is_featured %} featured{% endif %}
	{% if not article.published %} unpublished{% endif %}">
	{# The image is only shown on the detail view by using the condition "and detail_view" #}
	{% if not detail_view %}
		<!-- Preview code goes here -->
	{% else %}
		<!-- Main article code goes here -->
	{% endif %}
</article>

For my page I wanted a large thumbnail image with the title displayed at the bottom. I also wanted a visual indicator reflecting the article’s category that was done by adding javascript to change the div background colour.

HTML

<a class="news-a" href="{% namespace_url 'article-detail' article.slug namespace=namespace default='' %}">
	<div class="news-background" style="background-image:url({% thumbnail article.featured_image 300x169 crop subject_location=article.featured_image.subject_location %});">
		<div class="news-title-container">
			<div id="{{ article.slug }}" class="news-cat-bar"></div>
			<script>articleColor("{{ article.categories.first.name }}", "{{ article.slug }}");</script>
			<h2 class="news-title">{% render_model article "title" %}</h1>
		</div>
	</div>
</a>

CSS

.news-a {
    display: block;
    margin: 2px;
}
.news-background {
    position: relative;
    width: 300px;
    height: 169px;
    background-size: contain;
}
.news-cat-bar {
    width: 100%;
    height: 2px;
    position: absolute;
    top: 0;
    left: 0;
}
.news-title {
    color: white;
}
.news-title-container {
    width: 100%;
    background-color: black;
    position: absolute;
    bottom: 0;
    left: 0;
    padding: 0px 10px 0px 10px;
}

Javascript

function articleColor(cat, id) {
    var col = "white";
    if (cat == "Online") {
        col = "green";
    } else if (cat == "Life") {
        col = "red";
    }
    document.getElementById(id).style.backgroundColor = col;
    return;
}

The important things to remember to include amongst the HTML are the:

• article’s title: {% render_model article "title" %}
• uploaded featured image: {% thumbnail article.featured_image 800x450 crop subject_location=article.featured_image.subject_location %}
• article’s author: {{ article.author }}
• categories: {{ category.name }}
• publishing date: {{ article.publishing_date|date }}
• lead in: {% render_model article "lead_in" %}
• main article content: {% render_placeholder article.content language placeholder_language %}

The code for the main article can be similarly