FPLC Explained

Fast Protein Liquid Chromatography or FPLC (formerly called Fast Performance Liquid Chromatography) is an advanced technique used in biochemistry and molecular biology to separate, and sometimes purify, biomolecules, in particular, proteins. As with other types of liquid chromatography, FPLC employs a liquid mobile phase and a fixed stationary phase. The mobile phase, containing the molecules of interest, runs through the stationary phase which consists of one or more specialized resins or matrices responsible for the chromatographic separation. In addition, the flow rates and elution conditions in FPLC are all controlled automatically through a system of pumps, interconnecting tubes, and columns to achieve the desired result. In fact, FPLC is similar to a better known type of liquid chromatographic technique called High Performance Liquid Chromatography or HPLC. However, FPLC operates at relatively low pressure but with a relatively fast flow rate, which is the reverse of how HPLC works. Significantly, FPLC is pivotal for various downstream applications in medical diagnostics and scientific research. 

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The Mechanics Behind Measuring Electrical Conductivity of Solutions

Electrical conductivity of a solution refers to its ability to conduct electric current. The metric is used in several real-world applications including the monitoring of water supplies for purity, and when measuring the concentration of plant nutrients in a feed solution. It is also a component of some scientific tools like Fast Protein Liquid Chromatography (FPLC) where it is used to monitor the ionic strength of the mobile phase or buffer.  

Electrical conductivity occurs because of the presence of charged ions within a solution. Applying an electric potential across the solution causes the charged ions to migrate towards their respective oppositely-charged electrodes. As a result, the flow of ions mediates the passage of the electric current. Significantly, the conductivity level of the solution depends on a number of factors, the main ones being the concentration of ions in the solution as well as its temperature.

In this post, we investigate the units normally used to quantify this electrical phenomenon, how to actually measure the conductivity of solutions, and finally, its relationship to the TDS metric.

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Thermionic Emission

Thermionic emission is the process whereby charged particles (usually electrons), known as thermions, are emitted from the surface of a heated material, usually a metal. The process is driven by the extra thermal energy that is added to the system. As a result, energised electrons can overcome the surface barrier of the material and escape into the surrounding space. This phenomenon has been used in various applications, including vacuum diodes, cathode ray tubes and, more recently, mass spectrometry. 

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Repairing the AA Car Battery Solar Trickle Charger

The AA Car Battery Solar Charger is a perfectly good solar panel for ensuring that your car battery does not run down if the vehicle is not used often enough. Its one weakness, however, is the cable coming out of the solar panel, which is prone to breaking, in part because the gauge of the internal copper wire is so thin. Worse still, it is all too easy for a wire break to go unnoticed, since the cable's insulation can remain intact, and the blue flashing LED on the solar panel will continue to flash irrespective of whether the car battery is being charged or not. Consequently, if a wire break does occur inside the cable, there is a good chance you will be unaware of the problem and one day when you try to start your car - it won't! I encountered this very problem...and this is how I fixed it.

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Best Digital Multimeter for Electronics Work and for the Electronics Hobbyist

The digital multimeter is one of the most important tools in the electronics professional’s and electronics hobbyist’s toolbox, so much so in fact that electronics aficionados usually have more than one. However, digital multimeters are used not only by electronics enthusiasts but also by other professionals such as car mechanics and electricians, who often have slightly different needs with respect to multimeter specifications. As a consequence, the humble digital multimeter comes in a variety of different flavours which cater to the needs of different professions. Therefore the electronics hobbyist needs to know beforehand what specifications are appropriate for electronics work, and what he or she should be looking for when buying a digital multimeter. So what's the best multimeter for electronics work and what should a newly-minted electronics hobbyist be looking for in their new digital multimeter? Let's try to answer those questions.

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Wireless Weather Station Reviews for the UK

​Weather for us Brits is a big part of our daily lives - not surprising since our weather can be often so unpredictable. Many of us too are fascinated by the weather, its unpredictability, ​its variability from year to year, and with global warming entering into the equation and making weather more extreme, it is only going to get all the more​ wild and interesting. That is why more and more of us are getting into monitoring our local weather not only to make better decisions in our own personal lives but also to ​keep track of how ​our weather is changing over time. One of the weather monitoring tools that is within almost everyone's budgetary reach is the wireless home weather station, which ​usually consists of a central display unit with one or more wireless sensors ​sited around and outside the home. Of course, as with all electronic gadgets these days, the humble weather station exists in a ​plethora of different makes and models, each sporting a range of different features, ​making the choosing of the best weather station for the home a difficult and confusing task. That's why here at Approach Labs, we have taken the time to look into the variety of features that different home weather stations ​offer, and to compare the popular ​ones that are available to consumers here in the UK​ to help you decide what's the best wireless weather station to buy for your particular home.

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USB Breakout Board for V-USB

Summary: The objective here was to make a USB breakout board that incorporates the hardware required to implement the mostly-software-based USB protocol, V-USB from Ojective Development. The completed V-USB module is able to be connected to a range of Atmel AVR® microprocessors involved in various projects at the breadboard stage, obviating the need for additional USB circuit components be added separately to the project breadboard whenever USB functionality is required. The use of V-USB where the USB protocol is incorporated into the main project AVR microcontroller also replaces the need for a dedicated chip to handle the USB protocol.

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USART Debugger on the AVR Microprocessor

Summary: When trying to build an electronic device based around a microprocessor, it’s useful to have the microprocessor itself send back updates as it executes its code so that one is able to debug any problems with the device. The microprocessor type that I invariably use is an Atmel 8-bit AVR (most often the ATmega168) so this write-up will be focused on getting that system to work. So how do we get these debugging messages from the AVR microprocessor? One way is to use the USART capabilities of the AVR to communicate with a computer via an RS-232 serial connection. Although, the RS-232 serial connection represents an older way of doing things, it does work just as well, for our purposes anyway, as more modern methods, and is especially appropriate if you have an old unused computer lying around that could do with a new reason to live! Read More

Taotronics Mobile Phone / GPS Car Holder Permanent Mount

Summary: If you are the owner of a Taotronics car phone holder and, like me, you like the design and functionality it provides, but dislike suction cup attachments in general and the fact that it occassionally falls off the windscreen when the weather is warm, then check out this project where I convert the suction cup mount into a permanent mount for my car’s dashboard. Super-steady and no more messing around with the unpredicatbility of suction cups. Looks good too, although would have preferred it in black! Read More

Doorbell for the Deaf (or hearing-impaired) – DIY

Summary: The objective with this project was to create a visual signal on my treadmill that would alert me to when someone was ringing the front doorbell. Why a visual alert? Well, because I invariably have music blaring out of my in-ear headphones when I’m running and between that and the noisiness of the treadmill itself, I have, in the past, missed the delivery guy knocking at the front door. It is so annoying to have to go on a treasure hunt just to recover parcels that I could have easily received myself if only I had known that the doorbell had been rung. The final design involved a large red flashing LED to get my attention, controlled by a 556 timer chip (which is two 555 timer circuits in one package) and wired through internal house wiring to the doorbell. The enclosure housing the device was designed to fit into one of the bottle holders on the treadmill display console. Read More