# Search results

1. ### Understanding the logistics of oncolytic virotherapy

I have questions about a particular paper: Oncolytic Poxvirus Armed with Fas Ligand Leads to Induction of Cellular Fas Receptor and Selective Viral Replication in FasR Negative Cancer The authors explain that they're using an oncolytic virus to deliver membrane-bound Fas ligand to cells in a...
2. ### Henderson-Hasselbalch & phosphate buffers

Wow. I stared at that problem for 2 hours...I can't believe the answer was right there. Thanks for clearing that up.
3. ### Henderson-Hasselbalch & phosphate buffers

This is an example calculation about the phosphate buffer system from my Biochemistry textbook. Homework Statement If the total cellular concentration of phosphate is 20 mM (millimolar) and the pH is 7.4, the distribution of the major phosphate species is given by pH = pKa + log10...
4. ### Approximate uncertainty in area of circle

I just figured it out. Turns out it was a rounding error on my part, so what I rounded up to 4 * 108 should have actually been rounded down to 3 * 108.
5. ### Approximate uncertainty in area of circle

Homework Statement What is the approximate uncertainty in the area of a circle of radius 5.3 * 104 cm? Express your answer using one significant figure. Homework Equations A = pi*r2 The Attempt at a Solution Using the given radius, I found the area to be 8.8 * 109 cm2. And since...
6. ### H NMR of unknown sample (organic chem)

Yes it was. I would assume that means the signal really has nothing to do with the structure of the sample?
7. ### H NMR of unknown sample (organic chem)

Homework Statement Last week in organic chem lab, we were provided with an H NMR spectrum of an unknown compound with the formula C7H5NO3. I'm not terribly good at analyzing these spectra, but I've managed to figure out that I'm looking at 4-nitrobenzaldehyde. The only thing that's bothering...
8. ### Best organic chemistry book?

I'm no expert on textbooks, but I used Maitland Jones' 4th edition of Organic Chemistry and I found it to be extremely helpful.
9. ### Syn versus anti elimination

My bad. I meant to ask what the syn and anti arrangements favor. My organic textbook says that syn and anti are favored in the E2 reaction over both a 60o dihedral angle and a 120o dihedral angle. This makes sense to me, since these arrangements would require further rotation to make a planar...
10. ### Syn versus anti elimination

Can someone please help me understand the difference between syn and anti elimination in terms of what they favor? My [extremely] limited understanding leads me to believe that syn elimination favors E2 since it mimics frontside attack, which will not work for Sn2 since there is no net-bonding...
11. ### Reasons for unusual infrared spectrum?

Nope, we just put a small crystal into a drop of the oil. Come to think of it, it didn't really look like it dissolved very well. I remember trying to mix it around for a while.
12. ### Reasons for unusual infrared spectrum?

In my organic lab we recently isolated and crystallized the natural product usnic acid from dried lichen. An IR spectrum of the crystals dissolved in mineral oil was obtained, but it came out looking a bit strange. The thing that's really confusing me is that there is no band that would be...
13. ### Estimating area with finite sums

Oh, ok. I see what you're saying about the lengths. So would my midpoints be 7 and 19? What I'm trying to get at is if there's a really easy mathematical way to get the midpoints of these segments. At this point I'm basically being really methodical about it, using my elementary school...
14. ### Estimating area with finite sums

Homework Statement Use the midpoint rule to estimate the area under the graph of f(x) = 7/x and above the graph of f(x) = 0 from [1,25] using two rectangles of equal width. Homework Equations N/A The Attempt at a Solution So first I found \Deltax by using (b-a) / n and got (25 - 1)...
15. ### Calc - Derivatives and Differentiation of Logs

Ok, now I'm stuck again, but only on something minor. I now have 3y2(dy/dx) * ey3 + 2y(dy/dx) = 8x3 If I want to factor out a dy/dx, how can I combine the 3y2 with the ey3 ? Do I just lump them together, i.e. 3y2ey3 ? If so, my original answer was correct for the most part and I am still...
16. ### Calc - Derivatives and Differentiation of Logs

Is it (3y2 * dy/dx) * ey3, then? But isn't this not the chain rule?
17. ### Calc - Derivatives and Differentiation of Logs

OK, great. I'm still having major trouble with the second problem. This ey3 is driving me insane. Did you say that I need to use the chain rule on it? I'm really confused about this. I'm don't really understand the example of the chain rule you posted earlier. To me, it looks like it suggests...
18. ### Calc - Derivatives and Differentiation of Logs

Oh, OK I see. I'm not sure if I used the product rule correctly in this case. I'm still a bit shaky with some of these derivatives. Here is what I did: f '(x) = 1 * e-4x + x * -4e-4x Then simplifying to get e-4x - 4xe-4x as my final answer.
19. ### Calc - Derivatives and Differentiation of Logs

Really? Why wouldn't the x just go away? For example, d/dx (ex) = e ?
20. ### Calc - Derivatives and Differentiation of Logs

Homework Statement I have a few problems that are giving me some trouble: 1. Take the derivative of xe-4x 2. Find dy/dx and evaluate the slope for the curve ey^3 - 2x4 + y2 = 3 at (8,0) 3. Find dy/dx and evaluate the slope for the curve e-y - 4 = x2 + 1 at (-2,2) Homework Equations N/A...
21. ### Chemistry Molecular Geometry: NH3

I just came across another situation that confuses me. How do you rationalize the molecular geometries? For e- pair geometries, my understanding is that your goal is to minimize electron repulsion, therefore you use the geometry that will place the pairs as far away as possible from one another...
22. ### Chemistry Molecular Geometry: NH3

Homework Statement I'm trying to figure out the electron pair geometry of NH3. I know that its molecular geometry is a trigonal plane, and it has 4 electron pairs total, including one lone pair. Homework Equations N/A The Attempt at a Solution Should the e- pair geometry be a...
23. ### Energy liberation in ionic bonding

Homework Statement If removing electrons from atoms requires energy, and adding electrons to atoms usually liberates energy, then why is energy liberated when the ionic compound NaCl forms from the elements sodium and chlorine? Homework Equations None The Attempt at a Solution My solutions...
24. ### Sizes of atoms

So you're saying that, since the elements that are further down a period have more positive charges in the nucleus, the outer electrons are condensed inward and therefore the atom is smaller? At what point does this stop being true? Further down in the periodic table, as the number of total...
25. ### Sizes of atoms

Homework Statement I have a few questions here that say to identify which atom from each pair is larger. One pair is Be and B, and the other is P and Cl. Homework Equations N/A The Attempt at a Solution I know that Be is larger than B, and that P is larger than Cl. I'm just...
26. ### Average rate of change

Oh, ok. That makes sense. For some reason the equation you mentioned I should use isn't shown in my book.
27. ### Average rate of change

Homework Statement I have just started my first ever calculus course, and I'm having a little trouble with a simple rate of change problem. It says: Find the average rate of change of the given function between the following pairs of x-values. The given function is f(x) = x2+ x The given...
28. ### Chemical Amount?

Chemical Amount?? Hey guys, I'm looking for a little help with the whole concept of chemical amount. This question was posed during my intro chem lecture (assume a hydrogen atom's mass is 1 amu, and an oxygen atom's mass is 16 amu): How much oxygen does one need, to have the same number of...
29. ### One more trig identity

So would it simplify to cos2x / cosx, which would then simplify to cosx for my answer?
30. ### One more trig identity

Homework Statement I'm finally starting to understand proving trig identities, but I have just one more that I can't seem to figure out. secx - tanxsinx = cosx Homework Equations N/A The Attempt at a Solution Well first, I multiplied the tanx and sinx and came up with sin2x /...