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Comment: Re:Sure It's The Original? (Score 1) 120

by Reziac (#47439025) Attached to: Child Thought To Be Cured of HIV Relapses, Tests Positive Again

I had the thought that yeah, since mom is infected it could be a re-infection, but not necessarily through what I suspect you're thinking. Any accidental exchange of bodily fluids can suffice. Did mom have a cold sore and kiss the child on the lips? (Remember kids have potential breaks in the mouth due to new teeth) Might be enough.

Comment: That said... (Score 4, Informative) 51

by Rei (#47437451) Attached to: Sand-Based Anode Triples Lithium-Ion Battery Performance

... the greater your capacity, the less cycle life matters. If you want an EV that battery that will run a 250Wh/mi vehicle for an average 20 miles a day for 15 years, then you want it to cycle through about 30MWh. If you use a 100 mile (25kWh) battery pack, then that's 1100 cycles. If you use a 200 mile (50kWh) battery pack, then that's 550 cycles. If you use a 400 mile (100kWh) battery pack, then that's a mere 275 cycles. Actually, the improvement is even better than that in the real world, because the greater your capacity vs. how far you're actually driving, the more you can cycle the cells through a less destructive state of charge range rather than doing deep discharges.

A lot of people picture battery packs in EVs backwards, they think that things like hybrids stress the packs the least, PHEVs moderately, and EVs the worst. But it's reversed. If you look at how big hybrid packs are vs. how much electric range they hold, you'll see that they're disproportionately large, even after you factor in any differences in Wh/kg. The reason is that because hybrid packs get cycled so much, they have to keep the cycling in a very narrow state of charge range, only allowing shallow discharges. So if you only have a narrow discharge range, you have to make your pack bigger to make up for it. EVs can discharge through much more of their pack because they need fewer total cycles and only rarely go down toward the lower end of their allowable discharge range. Some EVs also let you limit the max that your pack charges up to to further extend lifespan (it's usually destructive both to use the very top end and the bottom end of the discharge range).

Comment: Re:Correct me if I'm wrong, but... (Score 4, Informative) 51

by Rei (#47437401) Attached to: Sand-Based Anode Triples Lithium-Ion Battery Performance

1024 mAhg1 is excellent capacity even vs. brand new graphite or amorphous carbon, about 3x as much as graphite's maximum. Silicon's theoretical max is 8-10x that of graphite, but the main problem with it is durability, it tends to tear itself apart on loading. There are silicon anodes in some newer li-ion cells on the market, but the tech is in its infancy.

That said, the real papers you want to be on the lookout for are cathode improvements, there's a lot more potential for volume/mass reduction there than in the anode. But it seems to be a more difficult challenge. Getting a 3x improvement in anode density is absolutely not the same a getting a 3x improvement in battery life.

Comment: Re:Little Bit of History Repeating. (Score 4, Insightful) 51

by Rei (#47437377) Attached to: Sand-Based Anode Triples Lithium-Ion Battery Performance

Commercial li-ion battery energy densities have continued to improve during that time period, including the commercial introduction of cells with silicon anodes. Of course, silicon anodes are a new tech, so there's a great deal of room for improvement, which probably won't come close to "maxing out" for a decade or more.

Of course, that said, this article is your typical fluff piece following the guidelines of fluff science reporting.

1. Present an oversimplified version of one technology challenge that may or may not address the biggest issue and certainly doesn't address all of them - but don't mention that.
2. Introduce an outside-the-establishment loner with a passion - or at least someone you can try to present as "outside the establishment" and glaze over anyone who helped him.
3. Loner gets a "vision" based on some everyday activity
4. Present their solution and make it out to be a huge revolution that will certainly solve all our problems - if they can only get corporate backing / funding!

I think these sort of articles hurt the image of science because people read them, think "OMG, all our problems are solved!", then when everything's not solved afterward, fail to trust science in the future. For example, in this case, the most important element to improve is the cathode, not the anode. And cathode improvements are less common and usually less major than anode improvements. There's also tons of different anode improvements out there in various stages of research. Pretty much all of the silicon ones get way better than graphite or amorphous carbon.

That doesn't mean that this isnt an important paper - actually, from looking at it, it looks pretty good. It's just not "all that".

BTW, anyone know how credible this journal is? I see it's hosted on Nature.com but not part of Nature, and I tried to find an impact rating for it but couldn't.

Comment: Re:Don't sweep it under the rug as collateral dama (Score 1) 145

You call that counterbalance?

What's keeping me, a rights owner of a movie that's a real stinker, from silencing everyone who dared to do a negative review of it by carpet bombing any and all media pages with takedown notices for those reviews?

Comment: Re:Alternate use for this technology (Score 1) 165

by Opportunist (#47437171) Attached to: DARPA Successfully Demonstrates Self-Guiding Bullets

The US learned that it's more profitable to wage than to win wars. At least for the elite few. It's really win-win in every aspect. You get the masses occupied with an external foe, you get the rabble off the street by dumping it into the army (and at the same time make them feel important because they're doing something important) and you can make the elite rich at the same time.

The US also has the economy to fuel the whole shit, unlike Germany in WW2. And also unlike Germany in WW2, they're not dumb enough to actually engage in a war with anyone who could actually fight back.

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