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Comment lower limit on neutrino mass? (Score 5, Interesting) 25

The experiment reports a new upper limit on the neutrino mass. I've seen upper limit estimates before this one, but I don't ever recall seeing a lower limit reported on a direct measurement of the neutrino mass. Nonzero mass is a requirement in standard theories of neutrino oscillation but that's a consequence of the theory, not a direct measurement. Is there a direct measurement of a lower limit out there that I'm not aware of?

Comment he's probably serious about this (Score 1) 602

I'm not a fan of Newt in any way, but he's probably fairly serious about wanting to resuscitate space exploration. He's had a long friendship with science fiction author Jerry Pournelle, to the point that they almost collaborated on a book before Newt became Speaker of the House. But like Pournelle his vision for space is far more right-wing and militaristic than that of most people here on /. or in NASA I expect.

Comment some observations from reading the paper (Score 3, Informative) 298

Just a couple points I want to make:

- Nowhere in the paper is there anything about using this stuff in ketchup bottles. I'm sure the researchers seized on this when they got interviewed as a simple way to explain lyophobicity to a general audience, the effect of which was to make "getting all the ketchup out of the bottle" the only thing anyone remembers. Typical.

- As for the significance of the research, there has been a ton of work in the last, oh, say 10-20 years on superhydrophobic surfaces, which have texture on the scale of a few nm that prevents water or other high surface tension liquids from penetrating into these tiny cracks. The water drops energetically prefer to remain as spherical as possible and so the liquid is repelled. This doesn't work with low surface tension liquids like light oils because it would rather penetrate inside the texturing than stay in a roughly spherical drop. The neat advance in this work is the addition of a low surface tension liquid which is introduced into the textured Teflon or fluorinated silane surface and repels both water and oil. They can use lots of different chemicals for the liquid, so as they continue the research they will find that some resist high heat, others are bio-inert, etc etc. so there are many possible applications.

Comment Re:Where's our futuristic paradise? (Score 1) 990

Well put. I'd like to see the various Occupy movements add these ideas to their discussion but they seem stuck on banks and the usual response to unemployment, ie. make more jobs. I'm no friend of the modern banking racket but I think technological advances have also contributed to increasing shareholders wealth at the expense of employees. What is needed is a radical move away from the idea that you *need* to work to live, with most of the efficiency savings from technological advances going into energy R+D and providing a guaranteed subsistence-level of income and education to all. We know birth rates go down when people's quality of life and education improve, so maybe we could stabilize world population before we run out of oil. Also by turning the focus away from job creation and economic growth we might be able to transition to a steady-state economy. Yeah, right. Well, I can dream can't I?

Space

Submission + - Space Is (Not) The Place (ucsd.edu)

snoop.daub writes: A while back, I posted about Dr. Tom Murphy at UCSD and his blog about limits on growth in energy use and economies. Partly in reaction to Slashdot's response (and my own writeup!) he's back with a blog post arguing that space is not a solution to enable continued growth. There's a lot of good stuff in here about public misconceptions regarding the difficulty of space travel and the like; again definitely worth the read.

Comment Re:Let me take a crack at this... (Score 1) 222

So I read the experimental part more carefully. Seems like in this case they aren't really using "functionalization" as it's usually understood, in that their membrane-forming molecules on the mica are not chemically bonded to the surface. Instead the molecules self-assemble on the mica in various ways depending on their concentration, adsorbing to the surface but not chemically bonding, and they examine the interactions between two of these surfaces-with-associated-membraney-things using the surface force apparatus.

Comment Re:Let me take a crack at this... (Score 1) 222

You've guessed the basic idea. Functionalization just generally means binding molecules to some kind of substrate to change the behaviour. It's used a lot on surfaces and these days with nanoparticles. Mica on its own is weakly hydrophilic (contact angle of water on the surface is a bit less than 90 degrees), but can be easily modified with molecules like those shown in Figure 1 to be more hydrophobic.

Comment Let me take a crack at this... (Score 5, Informative) 222

I work in the field on the theory/simulation side, and have actually had dinner and discussed research with Dr. Israelachvili a couple of times. I've only had a chance to skim the paper, but I think I can summarize it pretty well... by the time I've really absorbed it you folks will have moved on to the next shiny new story so I'd better do it now!

First of all, the report claims that the paper is all about how oil and water don't mix and makes a big deal about how we don't know how that works. For simple stuff like say water and a basic hydrocarbon like octane, that's really not true... it's all about what has already been said above, polar vs. nonpolar (electrostatics) and entropy.

Things get more complicated when you want to model something like an extended hydrophobic surface, or the interactions and formation of bilayer membranes like we have in a cell. It's been known from experiments since Dr. Israelachvili's work in the 80's that if you take two such surfaces (usually mica functionalized to make it hydrophobic) and bring them together in water, they will repel each other, up until at some point they very quickly strongly attract, expel the water between them and glue themselves together (also called "cavitation"). This is the sort of data shown in Fig. 2 in the paper. The connection with membrane formation is to describe how two membranes behave when they come close together, they have to do something similar to get close enough to fuse (figure 3).

Figuring out how to describe this behaviour from a theoretical standpoint has been very difficult! We know what all the parts have to be (hydrophobic,electrostatic, steric/Van der Waals, entropic) but haven't been able to put them together in the right way to describe all of the experimental data. What Jacob and his team have done here is found a nice way to 1) describe the hydrophobic interaction between extended surfaces mathematically (the equation above), 2) combine it with all the other parts (figure 4), and 3) show that the equation with a combination of fitted and measured parameters can fit the experimental data pretty well (Table 1). It's very nice work, definitely a step forward in our knowledge of hydrophobic surface and membrane interactions, and I'm going to make sure I study it more carefully soon!

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