Day: December 9, 2021

Mixing synthetic blood

The Challenges Of Finding A Substitute For Human Blood

December 9, 2021 by 19 Comments

Throughout history, the human body has been the subject of endless scrutiny and wonder. Many puzzled over the function of all these organs and fluids found inside. This included the purpose of blood, which saw itself alternately disregarded as being merely for ‘cooling the body’, to being responsible for regulating the body’s humors, leading to the practice of bloodletting and other questionable remedies. As medical science progressed, however, we came to quite a different perspective.

Simply put, our circulatory system and the blood inside it, is what allows us large, multi-celled organisms to exist. It carries oxygen and nutrients to cells, while enabling the removal of waste products as well as an easy path for the cells that make up our immune system. Our blood and the tissues involved with it are crucial to a healthy existence. This is something which becomes painfully clear when we talk about injuries and surgeries that involve severe blood loss.

While the practice of blood transfusions from donated blood has made a tremendous difference here, it’s not always easy to keep every single type of blood stocked, especially not in remote hospitals, in an ambulance, or in the midst of a war zone. Here the use of artificial blood — free from complicated storage requirements and the need to balance blood types — could be revolutionary and save countless lives, including those whose religion forbids the transfusion of human blood.

Although a lot of progress has been made in this field, with a limited number of practical products, it’s nevertheless proving to be a challenge to hit upon a replacement that ticks all of the boxes needed to make it generic and safe.

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Molding complex lenses

Molding Complex Optics In A Completely Fluid System

December 9, 2021 by 25 Comments

Traditional lensmaking is a grind — literally. One starts with a piece of glass, rubs it against an abrasive surface to wear away the excess bits, and eventually gets it to just the right shape and size for the job. Whether done by machine or by hand, it’s a time-consuming process, and it sure seems like there’s got to be a better way.

Thanks to [Moran Bercovici] at Technion: Israel Institute of Technology, there is. He leads a team that uses fluids to create complex optics quickly and cheaply, and the process looks remarkably simple. It’s something akin to the injection-molded lenses that are common in mass-produced optical equipment, but with a twist — there’s no mold per se. Instead, a UV-curable resin is injected into a 3D printed constraining ring that’s sitting inside a tank of fluid. The resin takes a shape determined by the geometry of the constraining ring and gravitational forces, hydrostatic forces, and surface tension forces acting on the resin. Once the resin archives the right shape, a blast of UV light cures it. Presto, instant lenses!

The interface between the resin and the restraining fluid makes for incredibly smooth lenses; they quote surface roughness in the range of one nanometer. The use of the fluid bed to constrain the lens also means that this method can be scaled up to lenses 200-mm in diameter or more. The paper is not entirely clear on what fluids are being used, but when we pinged our friend [Zachary Tong] about this, he said he’s heard that the resin is an optical-grade UV adhesive, while the restraining fluid is a mix of glycerol and water.

We’re keen to see [Zach] give this a try — after all, he did something similar lately, albeit on a much smaller scale.

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Ham Radio SSB Transceiver Fits In Pocket

December 9, 2021 by 32 Comments

Talking about this Chinese ham radio transceiver requires a veritable flurry of acronyms: HF, SSB, QRP, and SDR to start with. [Paul] does a nice job of unboxing the rig and checking it out. The radio is a clone of a German project and provides a low-power radio with a rechargeable battery. You can see his video about the gear below.

SSB is an odd choice for low power operation, although we wonder if you couldn’t feed digital data in using a mode like PSK31 that has good performance at low power. There are several variations of the radio available and they cost generally less than $200 — sometimes quite a bit less.

There isn’t much on the front of the radio. There are a few buttons, a rotary encoder, and an LCD along with a speaker and microphone built-in. There are ports for power to run the radio if you want to not use the battery and a separate port for battery charging. There are also ports for a key, external microphone and speakers, and audio connections that look like they’d work for digital modes. According to commenters, the radio doesn’t have an internal charging circuit, so you have to be careful what you plug into the charging port.

Looking inside, the radio looks surprisingly well made. Towards the end of the video, you can see the radio make some contacts, too. Looks like fun. This is a bit pricey for [Dan Maloney’s] $50 Ham series, but not by much. You might borrow an antenna idea from him, at least. If you prefer something more analog, grab seven transistors and build this SSB transceiver.

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