Survival mechanisms in Deinococcus radiodurans bacterium. (Credit: Feng Liu et al., 2023)

Bacterium Demonstrates Extreme Radiation Resistance Courtesy Of An Antioxidant

December 18, 2024 by 12 Comments

Extremophile lifeforms on Earth are capable of rather astounding feats, with the secret behind the extreme radiation resistance of one of them now finally teased out by researchers. As one of the most impressive extremophiles, Deinococcus radiodurans is able to endure ionizing radiation levels thousands of times higher than what would decisively kill a multicellular organism like us humans. The trick is the antioxidant which this bacterium synthesizes from multiple metabolites that combine with manganese. An artificial version of this antioxidant has now been created that replicates the protective effect.

The ternary complex dubbed MDP consists of manganese ions, phosphate and a small peptide, which so far has seen application in creating vaccines for chlamydia. As noted in a 2023 study in Radiation Medicine and Protection by [Feng Liu] et al. however, the D. radiodurans bacterium has more survival mechanisms than just this antioxidant. Although much of the ionizing radiation is neutralized this way, it can not be fully prevented. This is where the highly effective DNA repair mechanism comes into play, along with a range of other adaptations.

The upshot of this is the synthesis of a very effective and useful antioxidant, but as alluded to in the press releases, just injecting humans with MDP will not instantly give them the same super powers as our D. radiodurans buddy.

Featured image: Survival mechanisms in Deinococcus radiodurans bacterium. (Credit: Feng Liu et al., 2023)

Simple Fluorometer Makes Nucleic Acid Detection Cheap And Easy

December 18, 2024 by 9 Comments

Back in the bad old days, dealing with DNA and RNA in a lab setting was often fraught with peril. Detection technologies were limited to radioisotopes and hideous chemicals like ethidium bromide, a cherry-red solution that was a fast track to cancer if accidentally ingested. It took time, patience, and plenty of training to use them, and even then, mistakes were commonplace.

Luckily, things have progressed a lot since then, and fluorescence detection of nucleic acids has become much more common. The trouble is that the instruments needed to quantify these signals are priced out of the range of those who could benefit most from them. That’s why [Will Anderson] et al. came up with DIYNAFLUOR, an open-source nucleic acid fluorometer that can be built on a budget. The chemical principles behind fluorometry are simple — certain fluorescent dyes have the property of emitting much more light when they are bound to DNA or RNA than when they’re unbound, and that light can be measured easily. DIYNAFLUOR uses 3D-printed parts to hold a sample tube in an optical chamber that has a UV LED for excitation of the sample and a TLS2591 digital light sensor to read the emitted light. Optical bandpass filters clean up the excitation and emission spectra, and an Arduino runs the show.

The DIYNAFLUOR team put a lot of effort into making sure their instrument can get into as many hands as possible. First is the low BOM cost of around $40, which alone will open a lot of opportunities. They’ve also concentrated on making assembly as easy as possible, with a solder-optional design and printed parts that assemble with simple fasteners. The obvious target demographic for DIYNAFLUOR is STEM students, but the group also wants to see this used in austere settings such as field research and environmental monitoring. There’s a preprint available that shows results with commercial fluorescence nucleic acid detection kits, as well as detailing homebrew reagents that can be made in even modestly equipped labs.

Push For On, Hold For Off, AC Edition

December 18, 2024 by 18 Comments

A common theme in modern consumer electronics is having a power button that can be tapped to turn the device on, but needs to be held down when it’s time to shut it off. [R. Jayapal] had noticed a circuit design for this setup when using DC and decided to create a version that could handle AC-powered loads.

The circuit relies on a classic optoisolated triac to switch the AC line, although [R. Jayapal] notes that a relay would also work. The switch circuit consists of two transistors, a comparator, a flip flop and a monostable. As you might expect, the button triggers the flip flops to turn the triac on. However, if you hold the switch for more than a few seconds, a capacitor charges and causes the comparator to trip the output flip flop.

The DC circuit that inspired this one is naturally a bit simpler, although we might have been tempted to simply use the output of that circuit to drive a relay or triac. On the other hand, the circuit is set up to allow you to adjust the time delay easily.

Given the collection of parts, though, we wonder if you couldn’t press some 555s into service for this to further reduce the part count. If relays are too old-fashioned for you, you can always use a solid-state relay or make your own.

Upper Room UV-C Keeps Air Cleaner

December 18, 2024 by 59 Comments

2020 saw the world rocked by widespread turmoil, as a virulent new pathogen started claiming lives around the globe. The COVID-19 pandemic saw a rush on masks, air filtration systems, and hand sanitizer, as terrified populations sought to stave off the deadly virus by any means possible.

Despite the fresh attention given to indoor air quality and airborne disease transmission, there remains one technology that was largely overlooked. It’s the concept of upper-room UV sterilization—a remarkably simple way of tackling biological nastiness in the air.

Continue reading “Upper Room UV-C Keeps Air Cleaner” →

The added 3.3v rail on the Raspberry Pi 500 PCB. (Credit: Samuel Hedrick)

Enabling NVMe On The Raspberry Pi 500 With A Handful Of Parts

December 18, 2024 by 70 Comments

With the recent teardown of the Raspberry Pi 500, there were immediately questions raised about the unpopulated M.2 pad and related traces hiding inside. As it turns out, with the right parts and a steady hand it only takes a bit of work before an NVMe drive can be used with the RP500, as [Jeff Geerling] obtained proof of. This contrasts with [Jeff]’s own attempt involving the soldering on of an M.2 slot, which saw the NVMe drive not getting any power.

The four tiny coupling capacitors on the RP500’s PCIe traces. (Source: Jeff Geerling)

The missing ingredients turned out to be four PCIe coupling capacitors on the top of the board, as well as a source of 3.3 V. In a pinch you can make it work with a bench power supply connected to the pads on the bottom, but using the bottom pads for the intended circuitry would be much neater.

This is what [Samuel Hedrick] pulled off with the same AP3441SHE-7B as is used on the Compute Module 5 IO board. The required BOM for this section which he provides is nothing excessive either, effectively just this one IC and required external parts to make it produce 3.3V.

With the added cost to the BOM being quite minimal, this raises many questions about why this feature (and the PoE+ feature) were left unpopulated on the PCB.

Featured image: The added 3.3 V rail on the Raspberry Pi 500 PCB. (Credit: Samuel Hedrick)

Why Did Early CD-ROM Drives Rely On Awkward Plastic Caddies?

December 18, 2024 by 45 Comments

These days, very few of us use optical media on the regular. If we do, it’s generally with a slot-loading console or car stereo, or an old-school tray-loader in a desktop or laptop. This has been the dominant way of using consumer optical media for some time.

Step back to the early CD-ROM era, though, and things were a little kookier. Back in the late 1980s and early 1990s, drives hit the market that required the use of a bulky plastic caddy to load discs. The question is—why did we apparently need caddies then, and why don’t we use them any longer?

Caddyshack

Early CD players, like this top-loading Sony D-50, didn’t use caddies. Credit: Binarysequence, CC BY-SA 4.0

The Compact Disc, as developed by Phillips and Sony, was first released in 1982. It quickly became a popular format for music, offering far higher fidelity than existing analog formats like vinyl and cassettes. The CD-ROM followed in 1985, offering hundreds of megabytes of storage in an era when most hard drives barely broke 30 MB. The discs used lasers to read patterns of pits and lands from a reflective aluminum surface, encased in tough polycarbonate plastic. Crucially, the discs featured robust error correction techniques so that small scratches, dust, or blemishes wouldn’t stop a disc from working.

Notably, the first audio CD player—the Sony CDP-101—was a simple tray-loading machine. Phillips’ first effort, the CD100, was a top-loader. Neither used a caddy. Nor did the first CD-ROM drives—the Phillips CM100 was not dissimilar from the CD100, and tray loaders were readily available too, like the Amdek Laserdrive-1. Continue reading “Why Did Early CD-ROM Drives Rely On Awkward Plastic Caddies?” →