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Sarennah Longworth-Cook
Dr Sarennah Longworth-Cook is product technical specialist for laser diffraction based at our UK headquarters. With 12 years’ experience in characterization labs Sarennah is dedicated to helping our customers make high quality and meaningful measurements.

Laser Diffraction, Mastersizer, Particle size, Tech Talk »

[1 Aug 2017 | ]

Just when I thought I’d seen everything that could contaminate the background, a user sent me this picture! The Musca Domestica (common housefly) was attracted by certain aromatics used in testing and seems to have entered the measurement cell through an empty Hydro EV over a weekend. Unfortunately, it became wedged within the measurement cell and did not survive the experience.

The most important message from the Mastersizer training courses I give is to make sure you have a good background before you start. Laser diffraction is a background subtracted technique: …

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Meet the Experts »

[9 Aug 2016 | ]

Laser Diffraction – Q&As
As a product technical specialist at Malvern Instruments with over 12 years’ experience working in the material characterization industry, I thought I would share with you the questions and answers that I receive the most. Here are some of my top asked questions and the answers.
What is the formula for Dv10?
Dv10 is the 10th percentile of the cumulative volume distribution. It is the size below which there is 10% of the volume of the sample, so it is used to track changes to the finest particles in population. …

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Laser Diffraction, Mastersizer, Particle size »

[13 Aug 2015 | ]

One of the questions I am regularly asked by my Mastersizer customers is how much sample do I need to measure?
I get the feeling people are hoping for a simple answer, such as 1g, 10ml etc. Unfortunately, the science of sampling is not so straightforward…
An expert in sampling, Francis F Pitard, says “a sample is equitable when it is reproducible and accurate enough to satisfy both the supplier and the customer”. I take this to mean the results need to be reproducible AND have RSDs for the percentiles that satisfy …

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Laser Diffraction, Mastersizer, Particle size, Tech Talk »

[16 Jun 2015 | ]

Batteries, and the chargers for them, are everywhere. They are available in a wide range of specifications using a variety of chemistries. The characteristics of the battery are determined by the particle size of the electrolyte powder, or slurry, and the surface roughness of the electrodes, which is determined by the particle size of its coating. By controlling the surface area, through particle size, a battery can be optimised for high capacity or high power.
The capacity of a battery is the amount of electrical charge it can deliver at the …

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Laser Diffraction, Particle size, Tech Talk »

[28 May 2015 | ]

I was stuck in traffic on the M8 travelling between Edinburgh and Glasgow when a news item really pricked my ears up. Scientists from Edinburgh University’s school of GeoSciences have been investigating better ways of measuring the extent of ash clouds following volcanic eruptions, looking at particle size.Following the Eyjafjallajokull Icelandic volcano eruption in 2010, the ash cloud drifted across the major flight paths in the North Atlantic and over Northern Europe and as a result, planes were grounded and people stranded. At first the airlines said they wouldn’t fly …

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Archimedes, Insitec, Laser Diffraction, Malvern Panalytical Events, Mastersizer, Morphologi, Nanosight, Spraytec, Tech Talk, Zetasizer »

[10 Feb 2015 | ]

As a confirmed space-geek ever since Halley’s Comet in 1986, lasers, or perhaps I should say laser guns in their various forms, have always been a part of my life. I’m not sure if I first met lasers in Star Wars or being fired at Doctor Who by a Dalek. But I do know they made a big impression on me. The lasers of sci-fi are flashy affairs, complete with awesome graphics, sound effects and implausible physics. Perhaps the most iconic being the lightsaber of Luke Skywalker. So I was …

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Dynamic Light Scattering, Laser Diffraction, Malvern Panalytical Events, Mastersizer, Meet the Experts, Particle size, Zetasizer »

[19 Dec 2014 | ]

I’m just back from DDL25, the Drug Delivery to the Lungs conference in Edinburgh. Unlike previous years the snow wasn’t here to stay and we were able to enjoy the conference without too many meteorological distractions.
It was the 25th DDL and retrospection was the order of the day, with the DDL Lecture given by Prof Peter Stewart (Monash University) reviewing the history of powders for inhalation from 1989 to today and offering predictions of developments in the next 25 years. In 1989, powder scientists were beginning to consider inhalation, and what …

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Laser Diffraction, Mastersizer, Meet the Experts, Particle shape, Particle size, Spraytec, Tech Talk »

[3 Dec 2014 | ]

I’ll be manning the Malvern stand at DDL25 – the 25th Drug Delivery to the Lungs conference – which is taking place in Edinburgh next week, starting on 10th December.  I’m a technical specialist for diffraction products at Malvern, so I know the Mastersizer and Spraytec instruments inside out.  My challenge to you is to bring along your dodgy data for me to diagnose!
Got problems with your MDI? No, not your metered dose inhalers, your Method Development Investigations!  Need help with your API? I’m talking about Awkward Peak Investigations, not …

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