Polish that Chrome!

Chromium is the first of the group 6 transition metals. It is denoted by the symbol Cr and atomic number 24. Chromium is a grey coloured, hard and very lustrous metal.  It takes a high polish, resists tarnishing, and has a high melting point. The name of the element is derived from the Greek word "chrōma" (χρώμα), meaning colour.

Chromium is highly corrosion resistant, a character that it brings with it when added to steel to create stainless steel. Another popular use for chromium is electroplating, which gives hubcaps, bumpers and other shiny bits of cars their street-cred.

Many of its compounds are intensely coloured. Besides providing the familiar non-fading "chrome yellow" colour used on American school buses and by the German postal service, there is the bright red pigment, chrome red (PbCrO₄·Pb(OH)₂), a bright green (Cr₂O₃), a pale green ([CrCl(H₂O)₅]Cl₂), and rich violet ([Cr(H₂O)₆]Cl₃). Trace amounts of chromium also gives rubies and emeralds their characteristic colours.

Below is the relatively rare mineral, crocoite (PbCrO₄), the state mineral of Tasmania.

Chromium is the 24th most abundant element in Earth's crust with an average concentration of 100 ppm. Chromium compounds are found in the environment, due to erosion of chromium-containing rocks and can be distributed by volcanic eruptions. The concentrations range in soil is between 1 and 300 mg/kg, in sea water 5 to 800 µg/litre, and in rivers and lakes 26 µg/litre to 5.2 mg/litre.  Chromium is mined as chromite (FeCr₂O₄) ore.  About two-fifths of the chromite ores and concentrates in the world are produced in South Africa, while Kazakhstan, India, Russia, and Turkey are also substantial producers. Untapped chromite deposits are plentiful, but geographically concentrated in Kazakhstan and southern Africa

In the laboratory Chromic acid is a powerful oxidizing agent and is a useful compound for cleaning laboratory glassware of any trace of organic compounds. It is prepared in situ by dissolving potassium dichromate in concentrated sulfuric acid, which is then used to wash the apparatus. Sodium dichromate is sometimes used because of its higher solubility (50 g/L versus 200 g/L respectively). The use of dichromate cleaning solutions is now phased out due to the high toxicity and environmental concerns. Modern cleaning solutions are highly effective and chromium free. Potassium dichromate is a chemical reagent, used as a titrating agent. It is also used as a mordant (i.e., a fixing agent) for dyes in fabric.

For more information visit:-
http://www.theguardian.com/science/punctuated-equilibrium/2011/aug/12/1?guni=Article:in%20body%20link
http://en.wikipedia.org/wiki/Chromium

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Hangnails!!

A hangnail or agnail (also known as a stepmother's blessing particularly in the Lancashire region) is a corruption of agnail which literally means painful (anguished) nail.

Hangnails can seem rather insignificant in the grand scheme of health problems but they can become infected and lead to a handful of other issues. Fortunately, there are many ways to avoid hangnail hazards.

Hangnails don't have anything to do with your fingernails. Many people confuse hangnails with ingrown nails, a condition in which the corner of your nail grows into the soft skin of your nail bed.  In fact, hangnails are the dry, sometimes brittle triangular-shaped tags of skin around your fingernails that can tear off.  Because there are many different causes of hangnails, everyone gets them occasionally. But chronic, consistent hangnails can lead to bigger problems.

When the skin around your fingernails tears off, it opens the door to infection, especially when you consider all the bacteria your hands are exposed to every day, not to mention dishwater, cold weather and all the other things that dry out your hands in the first place. Fortunately, there are quick and easy ways to prevent hangnails that range from moisturising often to pampering your hands with cuticle soaks and manicures.

If you just can't beat hangnails, there are also easy ways to treat them. Antibacterial lotions can often do the trick, and in more serious cases, a prescription antibiotic might be in order.

Of course, before you can avoid hangnails, you need to know what causes them.

Hangnails are more common during the cold winter months. During the winter, skin dries out really fast which is one of the main causes of hangnails. Anything that can dry out your skin, such as cold winter weather, harsh chemicals or frequent immersion in water can cause hangnails to develop.

If you are a nail biter it can damage your nail bed, which is the skin underneath the actual fingernail and a weak nail bed can result in more hangnails.

Hangnails that aren't properly cared for can result in an infection called paronychia. There are three types of paronychia infection: bacterial, Candidal -- which is a type of yeast -- and fungal

Now that you know how hangnails happen, you're probably wondering how you can stop them before they start.

• Moisturise your hands and your nail beds.  Moisturising your nail beds helps your nails and your cuticles as well which can have a big impact on your overall nail health
• Stop biting your nails.
• Manicure.
• Wear gloves if you are exposed to harsh chemicals or even just soapy water from washing the dishes.

Working in a laboratory can cause a number of hand problems including latex glove allergies.  Make sure you choose the right gloves for your skin and for the job in hand.  Remember to wash your hands properly and moisturise afterwards.

Remember P&R Labpak offers a range of soaps and moisturisers for laboratories so you don’t need to suffer from hangnails!  The new VWR Safety catalogue is also available covering everything you need relating to personal protection, workplace safety, first aid and housekeeping.  Ask for your copy now!

For more information visit:-

http://en.wikipedia.org/wiki/Hangnail

http://health.howstuffworks.com/skin-care/nail-care/health/hangnails.htm

Filter Papers and Membrane filters.

Laboratory filter paper is a semi-permeable barrier placed perpendicular to a liquid or air flow. It is used to separate fine solids from liquids or air.

Filter paper comes in various porosities and grades depending on the applications it is meant for. The important parameters are wet strength, porosity, particle retention, flow rate, compatibility, efficiency and capacity.

There are two mechanisms of filtration with paper; volume and surface. By volume filtration the particles are caught in the bulk of the filter paper. By surface filtration the particles are caught on the paper surface. Filter paper is mostly used because even a small piece of filter paper will absorb a significant volume of liquid.

The raw materials are different paper pulps. The pulp may be from softwood, hardwood, fibre crops, mineral fibres.

For laboratory use filter papers are made in a variety of ways since specific applications require specific types of papers. The raw materials might be acid washed wooden fibres, carbon or quartz fibres.

In laboratories, filter paper is usually used with a filter funnel, Hirsch, or Buchner funnel.

Ashless filter paper is mainly used for gravimetric methods in quantitative chemical analysis.

 

The link here is useful as it contains a basic guide to choosing the right filter paper grade.


Glass fibre filters are commonly used in laboratories.  The manufacturer Whatman for example offers two types of glass microfiber filters manufactured from 100% borosilicate glass: binder free glass microfiber that is chemically inert and binder glass microfiber.

These depth filters combine fast flow rates with high loading capacity and the retention of very fine particle, extending into the sub-micron range. Glass microfiber filters can be used at temperatures up to 500°C and are ideal for use in applications involving air filtration and for gravimetric analysis of volatile materials where ignition is involved.

 

There are a number of manufacturers and include Whatman, Millipore, Sartorius, Munktell, Pall, Nalgene and more.

 

A Membrane Filter typically traps contaminants larger than the pore size on the addressed surface of the membrane. Contaminants smaller than the rated pore size may pass through the membrane or may be captured within the membrane by other mechanisms. Membrane filters are typically used for critical applications such as sterilising and final filtration.

A useful weblink can be found here.

 

When choosing a membrane filter a number of factors have to be considered, for example:-

• Depth vs Membrane filtration
• Chemical compatability
• Hydrophilic vs Hydrophobic
• Pore size
• Thermal stability

Filtration is a huge area to cover with a short blog article but hopefully the links will prove useful for anyone looking to broaden their knowledge.

 

The Bunsen Burner

Robert Wilhelm Bunsen (1811-1899), a German chemist and inventor is credited with inventing the Bunsen burner, a gas burner used in scientific laboratories.

With Gustav R. Kirchhoff they pioneered work with spectrum analysis, inventing the spectroscope to detect chemicals by the colours they give off when burning. Using this instrument, they discovered the elements caesium (1860) and rubidium (1861).

Bunsen improved the efficiency of blast furnaces after observing gases escaping from them and devising a method of gas analysis. His other inventions include the ice calorimeter, a filter pump, a zinc-carbon electric cell, and the magnesium light. With Sir Henry Roscoe he did important work in the field of photochemistry.

The Bunsen Burner is used for heating chemicals, boiling water, sterilising small objects, preparing microscopic slides, bending glass tubing, and many other purposes.

The Bunsen burner consists of a straight metal tube, about five inches (13 cm) long, fastened to a stand. The bottom is connected by rubber tubing to a source of illuminating gas. Adjustable openings at the base of the burner admit air. The mixture of gas and air produces a very hot flame. Nozzles of various types can be fitted to the top of the burner to control the flame's shape.

Bunsen burner flames depend on air flow in the throat holes (on the burner side, not the needle valve for gas flow): 1. air hole closed (safety flame used for lighting or default), 2. air hole slightly open, 3. air hole half open, 4. hole almost fully open (roaring blue flame).

Flame Test

This is a method of detecting the presence of certain metals by the colours they give off in the flame of a Bunsen burner. A platinum or nichrome wire is dipped in a powder or solution of the compound to be tested, and the compound is then placed in the flame. Barium gives a green flame; calcium, orange; caesium, blue; copper, greenish blue; potassium, violet.

If more than one metal is present, the test is unreliable as one colour obscures another. Except in rough, preliminary analyses, the flame test is little used by chemists. There are more precise methods of identifying elements.

Other burners based on the same principle exist. The most important alternatives to the Bunsen burner are:

Teclu burner
The lower part of its tube is conical, with a round screw nut below its base. The gap, set by the distance between the nut and the end of the tube, regulates the influx of the air in a way similar to the open slots of the Bunsen burner. The Teclu burner provides better mixing of air and fuel and can achieve higher flame temperatures than the Bunsen burner.


Teclu Burner

Meker burner
The lower part of its tube has more openings with larger total cross-section, admitting more air and facilitating better mixing of air and gas. The tube is wider and its top is covered with a wire grid. The grid separates the flame into an array of smaller flames with a common external envelope, and also prevents flashback to the bottom of the tube, which is a risk at high air-to-fuel ratios and limits the maximum rate of air intake in a conventional Bunsen burner. Flame temperatures of up to 1100–1200 °C (2000–2200 °F) are achievable if properly used. The flame also burns without noise, unlike the Bunsen or Teclu burners

Meker Burner

For more information visit:-
http://science.howstuffworks.com/dictionary/famous-scientists/chemists/robert-wilhelm-bunsen-info.htm

http://en.wikipedia.org/wiki/Bunsen_burner

http://www.prlabs.co.uk

The Northern Lights or Aurora Borealis

The Northern Lights or Aurora Borealis

An aurora is a natural light display in the sky particularly in the high latitude (Arctic and Antarctic) regions, caused by the collision of energetic charged particles with atoms in the high altitude atmosphere (thermosphere). The charged particles originate in the magnetosphere and solar wind and, on Earth, are directed by the Earth's magnetic field into the atmosphere. Most aurorae occur in a band known as the auroral zone, which is typically 3° to 6° in latitudinal extent and at all local times or longitudes. The auroral zone is typically 10° to 20° from the magnetic pole defined by the axis of the Earth's magnetic dipole. During a geomagnetic storm, the auroral zone expands to lower latitudes.

 

In northern latitudes, the effect is known as the aurora borealis (or the northern lights), named after the Roman goddess of dawn, Aurora, and the Greek name for the north wind, Boreas, by Pierre Gassendi in 1621.

Auroras seen near the magnetic pole may be high overhead, but from farther away, they illuminate the northern horizon as a greenish glow or sometimes a faint red, as if the Sun were rising from an unusual direction. Discrete aurorae often display magnetic field lines or curtain-like structures, and can change within seconds or glow unchanging for hours, most often in fluorescent green.

Its southern counterpart, the aurora australis (or the southern lights), has features that are almost identical to the aurora borealis and changes simultaneously with changes in the northern auroral zone. It is visible from high southern latitudes in Antarctica, South America, New Zealand, and Australia.

Aurora timelapse:-

 

What is happening?

The auroras, both surrounding the north magnetic pole (aurora borealis) and south magnetic pole (aurora australis) occur when highly charged electrons from the solar wind interact with elements in the earth's atmosphere. Solar winds stream away from the sun at speeds of about 1 million miles per hour. When they reach the earth, some 40 hours after leaving the sun, they follow the lines of magnetic force generated by the earth's core and flow through the magnetosphere, a teardrop-shaped area of highly charged electrical and magnetic fields.

­As the electrons enter the earth's upper atmosphere, they will encounter atoms of oxygen and nitrogen at altitudes from 20 to 200 miles above the earth's surface. The colour of the aurora depends on which atom is struck, and the altitude of the meeting.

• Green - oxygen, up to 150 miles in altitude
• Red - oxygen, above 150 miles in altitude
• Blue - nitrogen, up to 60 miles in altitude
• Purple/violet - nitrogen, above 60 miles in altitude

All of the magnetic and electrical forces react with one another in constantly shifting combinations. These shifts and flows can be seen as the auroras "dance," moving along with the atmospheric currents that can reach 20,000,000 amperes at 50,000 volts.

Structure of the Magnetosphere

For more information visit:-

http://science.howstuffworks.com/nature/climate-weather/atmospheric/question471.htm

http://en.wikipedia.org/wiki/Aurora_borealis

Using digital SLRs to measure the height of Northern Lights

Scientific research doesn’t often start from outreach projects. Yet, Ryuho Kataoka from the National Institute of Polar Research in Tokyo, Japan, came up with an idea for a new method to measure the height of aurora borealis after working on a 3D movie for a planetarium. Kataoka and collaborators used two digital single-lens reflex (SLR) cameras set 8 km apart to capture 3D images of Northern Lights and determine the altitude where electrons in the atmosphere emit the light that produces aurora. The results are published today in Annales Geophysicae, a journal of the European Geosciences Union (EGU).

“We had initial success when we projected the digital SLR images at a planetarium and showed that the aurora could be seen in 3D. It was very beautiful, and I became confident that it should be possible to calculate the emission altitude using these images,” recalls Kataoka, who also works at the Graduate University for Advanced Studies (Sokendai) in Hayama, Japan. He teamed up with other Japanese researchers and an American scientist to do just that.

The separation distance between the human eyes is what allows us to see in 3D. When we look at an object, the images captured by the left and right eyes are slightly different from each other and when combined they give the brain the perception of depth. But because the distance between our eyes – about 5 cm – is small, this only works for objects that are not very far away.
Since aurora extend between about 90 and 400 km in altitude, a much larger separation distance is needed to see them in 3D. The researchers used two cameras, mimicking the left and right eyes, separated by 8 km across the Chatanika area in Alaska. Their two digital SLRs, equipped with fisheye lenses and GPS units, captured two simultaneous all-sky images that the researchers combined to create a 3D photograph of the aurora and measure the emission altitude.

“Using the parallax of the left-eye and the right-eye images, we can calculate the distance to the aurora using a [triangulation] method that is similar to the way the human brain comprehends the distance to an object,” explains Kataoka. Parallax is the difference in the apparent position of an object when observed at different angles.

Scientists have obtained altitude maps of aurora before. They are useful because they provide information about the energy of the electrons that produce the lights. But this is the first time the emission height of Northern Lights has been measured using images captured with digital SLR cameras. As the authors explain in the new Annales Geophysicae paper, the altitude maps obtained in this way are consistent with previous observations.
The technique is low cost and allows researchers to measure the altitude of small-scale features in the aurora. Further, it opens up the door for citizen scientists to get involved with auroral research.

“Commercially available GPS units for digital SLR cameras have become popular and relatively inexpensive, and it is easy and very useful for photographers to record the accurate time and position in photographic files. I am thinking of developing a website with a submission system to collect many interesting photographs from night-sky photographers over the world via the internet,” says Kataoka.

The researchers believe this may lead to new scientific findings, while working to engage the public in auroral research. After all, it was the beauty of 3D imaging of auroras that inspired Kataoka to develop a new tool for scientific research in the first place.

For more information, the scientific article is available online, free of charge, at http://www.ann-geophys.net/31/1543/2013/angeo-31-1543-2013.html.