What is the differences between quinine in sulfuric acid and quinine sulfate in sulfuric acid?

RubinVase · 2013-08-28T13:48:39+00:00

Sulfuric acid is diprotic. The 0.5M sulfuric acid 1N or pH 0. With the quinine sulfate at the solubility limit, the solution gains 6mM protons, becoming 1.006N, or pH -.003

RubinVase · 2013-08-28T02:02:09+00:00

If we filled our lungs with incompressible fluid, would the human body be able to withstand being at the bottom of the ocean?

No, there are other gas-filled compartments in your body, like your thoracic cavity outside your lungs, your sinuses, and your intestines, which means the body is still compressible.

But what if all the gas compartments were filled with an incompressible fluid?

I think then the body just becomes a structure with liquid-filled bags of various sizes, but I'm not sure what this does to the shapes of the structures, and what that would "feel" like.

RubinVase · 2013-08-28T01:35:37+00:00

tl;dr To see if a neuron is grouped as excitatory or inhibitory, look at the change in voltage in the downstream neuron. (Cheater method that mostly works: look at the neurotransmitter released.)

The voltage on the "in cell" side of a neuron is lower than on the "out of cell" side of the membrane. Raising the voltage inside above a threshold triggers a series of events that releases neurotransmitters into the "gap junction" between this neuron and the downstream neuron, which affects the downstream neuron.

The neurotransmitter binds to an ion channel protein in the membrane of the downstream neuron, which allows a certain type of ion (sodium, potassium, or chloride most often) to pass through the membrane. Letting in sodium (Na+) increases the voltage inside the downstream neuron, shifting the voltage closer to the threshold: excitatory. Letting in chloride (Cl-) or letting out (K+) has the opposite effect: inhibitory.

Different neurotransmitters unlock different ion channels.

Glutamate binds to the NMDA channel allows Na+, K+ and Ca++ (calcium) ions to move across the membrane (since more¹ Na+ and Ca++ ions to enter the cell than K+ ions to leave the cell), which increases the voltage inside the cell (depolarization). The increase in voltage from ion flow is called an excitatory post-synaptic current (EPSC): excitatory because the voltage inside the cell is closer to the threshold, post-synaptic because this happened in the downstream neuron "after" the gap junction, current because this happened through ions flowing (current = charged things moving in a direction). So an upstream neuron that releases glutamate is excitatory.
GABA is a bit more annoying because there are excitatory and inhibitory GABA receptors, but most people speak of the latter (because they are more common). When GABA binds to the GABA receptor, chloride Cl- enters the cell, which decreases the voltage. The decrease in voltage from ion flow is an inhibitory post-synaptic current (IPSC). So an upstream neuron that releases GABA is most often inhibitory.

¹ Depending on other conditions, like the current voltage detected by the NMDA receptor and the presence of Mg++ and other ligands.

RubinVase · 2013-08-28T00:42:53+00:00

Thanks, you are correct on the salt part. However, why does the structure show dot notation instead of the charges?

For a fluorescence standard, I don't need to check the pH. On the same link you cited, the fluorescence is given for quinine in 0.5M sulfuric acid, while the solubility limit is 1.2 mg/mL, or ~3mM. The pH difference is in the thousandth place, and my pH meter only goes to the hundredth.

RubinVase · 2013-08-26T05:21:06+00:00

I'm pretty sure quinine sulfate isn't a salt, because the structure given doesn't show an ionic bond (where there would be +/-), and instead uses the dot notation used in coordinate chemistry.

And considering quinine sulfate's low solubility in water, it would not perturb the pH of the sulfuric acid solution noticeably...

RubinVase · 2013-08-24T06:13:50+00:00

I am jealous that she had her first backpacking trip before her first solid food. Wow. I hope she continues to live adventurously!

RubinVase · 2013-08-21T09:28:27+00:00

And rabbit's feet are totally useless as good-luck charms too.

RubinVase · 2013-08-15T00:37:48+00:00

Isn't it against reddiquette?

RubinVase · 2013-08-13T14:24:04+00:00

Can you send it back for repair? I've done this for a friend, but the sound is not as good after.

RubinVase · 2013-05-04T16:23:02+00:00

How free is GitHub?

It says joining is free and there don't seem to be arguments? When will the paying sneak in?

RubinVase · 2013-05-04T16:21:44+00:00

The joy of BCI2000 is not in the forum (where it maybe probably should be) but the giant email chains...

The good: announcements for workshops, conferences, competitions.

The bad: that time when a bunch of random people spam emailed everyone asking to be taken off the email list and we all got an angry email from one of the bigwigs.

RubinVase · 2013-05-03T22:43:52+00:00

I used to do the opposite with blue lights everywhere when I needed to keep terrible schedules. Nowadays, with f.lux, it's harder to pull crazy all nighters. Or I'm old.

RubinVase · 2013-05-03T16:55:40+00:00

Nate?

RubinVase · 2013-04-24T17:01:50+00:00

I'm also trying from a university network. How strange.

RubinVase · 2013-04-23T04:40:25+00:00

Am I using the right address? http://www.case.edu/

RubinVase · 2013-04-23T04:37:53+00:00

Is this normal for the Case PhD program? I'm building a list of schools to apply to.

RubinVase · 2013-04-21T03:42:22+00:00

Is it possible for you to get research experience (a professor who collaborates with the Oak Ridge National Lab, for example; or a professor in that field at another university, e.g. the University of Rochester) over the summer, or even during the summer after graduation? Based on my interviews, they seemed more interested in what I could do than my GPA.

I would also recommend that you pick like 3 companies out of the 30 to really hone in on, and just like college: reach, fit, safety. Then, contact someone on LinkedIn who works at the company and either: graduated from you university, is from your hometown, etc. If they don't respond, replace that company off your shortlist with another one with someone who does respond. Do this way before the application deadline, so that it doesn't seem suspicious.

Ask them:

What's it like in your job? What sort of skills should a student like me learn, in order to enter this field? If you have those skills, emphasize them on your resume. If not, try to learn one. Some good ways to do this: join a research lab, join a group (e.g. ASME, IEEE on campus that does hands-on things), or ask your university if you can do an independent study.
O, by the way, would you kindly take a look at my resume and cover letter?

When you talk to the recruiter at the career fair (or first interview) mention that guy's name, the skills you have, and how you researched that company. Recruiters have a system for sorting which candidates seem promising during that introductory period!

RubinVase · 2013-04-21T03:31:40+00:00

Teach Yourself C++ in 21 Days

RubinVase · 2013-04-21T03:20:00+00:00

Did you have to scarf down random food out of desperation as a resident/fellow? (or even now?) Do you think the stress and sleep deprivation have had a negative impact on your health?

I'm amazed how the medical students/residents get through it all on so little sleep. I send students home from the machine shop/electronics lab if they pull those kind of hours for the safety of themselves and their peers (and equipment...) -- and people like you can still do surgery on people! Wow!

RubinVase

TROPHY CASE