Recent Changes

- 217 C
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C Source
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- 218 C (Product Spec.) Source
- 254 C (TEA: bioactivity and therapeutic potential by Zhen) Source

Guest lecturer Rajarshi Guha from the NIH Chemical Genomics Center discusses Molecular Representation, Similarity and Search (Watch Talk)(Slides)
Guest lecturer Antony Williams from ChemSpider will discuss ChemSpider Tricks and Special Topics in Chemical Information (Watch Talk)(Slides)
Final Exam

3)Mann, Micheal, and Gavin Schmidt. "Peer Review: A Necessary But Not Sufficient Condition." RealClimate. Web. 27 Oct. 2009. http://www.realclimate.org/index.php/archives/2005/01/peer-review-a-necessary-but-not-sufficient-condition/.
[ C. Petrongolo] [Full Marks JCB]
author-side fees?
Open Access journals vary in whether they require publication fees from the author. By submitting to an open access journal, the author may have to pay to have the article open to the public, without need of a subscription. Bill Hooker carried out a survey of the chemistry journals in the Directory of Open Access Journals and found the following:
49% of open access journals do not charge publication fees,
An example a gradual change is Royal Society of Chemistry's Open Science[1]. A sudden conversion would be much like Hindawi Publishing Corporation, which is a smaller company that attempted to start in a toll market and was struggling, then the company decided to change over to the open access directory methods [1].
The list of companies that converted from Toll Access to Open access is here
for viewers. [note from Bill Hooker: see DOAJ also JCB]
The opposite scenario of when an Open access journal changes to a Toll Access. When this happens all of the existing free documents remain free, however anything added after that day the public will have to pay to access. An example of this would be what happened with the Journal of Visualized Experiments[3].
References:

Precompetitive preclinical ADME/Tox data (Ekins and Williams)
List of Free Chem Databases by Rich Apodaca
UCSB chemical literature resource
Free
ChemSpider

Find 5 independent sources of 5 properties associated with a molecule of your choice. Provide all references. (see jcblog as an example of the format) Due November 12, 2009
Optional Puzzles
main report. [Note: so far nobody has solved a puzzle - compare the two or more Chemspider entries for the compound and show how the stereochemistry is proved in one of the references - that will usually require re-analyzing the relevant part of the NMR or other spectroscopic evidence from scratch. This is a very difficult challenge. JCB]
1. Paromomycin
2. Hygromycin B

Instructor: Jean-Claude Bradley bradlejc AT drexel.edu
getcheminfo.wikispaces.com
The final exam is scheduled for Thursday December 10, 2009 18:00-20:00 in Korman 111
Lecture 1 September 24, 2009
General introduction to the class and the wiki.

Recent developments in the commercial manufacture of instruments that are able to produce and withstand pressures as high as 18,000 psi, along with the introduction of a new generation of columns packed with sub-2μm porous particles, have made it possible to achieve faster separations than in HPLC, while maintaining or increasing efficiency. The factors influencing chromatographic efficiency in Ultra High Performance Liquid Chromatography (UHPLC) that uses sub-2μm porous particles and the means to improve efficiency are reviewed herein.
2. Chemistry of small particles
separations in Liquid Chromatographyliquid chromatography mean symmetrical
1. Eddy diffusion: multiple paths of different length and velocity;
and mobile phase (inphase. In the case of the stationary phase).phase.
3. Longitudinal diffusion: diffusion of the analyte in the mobile phase.
must be limited.minimized. Therefore, using and hence improvingimprove efficiency. This supported by the Van Deemter (1., 2., 3.) -3.), an empirical velocity, u (or flow(flow rate), and height, H (or HETP(HETP or column
1. {Van_Deemter_eq..JPG} [5]
or simplified
Figure 1. {Van_Deemter_plot.JPG} [1]It is evident that when the particle size is reduced, the minimum plate height is decreased and the optimum velocity (point on the curve at the minimum plate height) is increased [1]. Then optimum flow rate is inversely proportional to particle size: Fopt ∞ 1/dp [6]. The flat part of the curve at higher linear velocities signifies that operating at the velocities above the optimal value results in an insignificant decrease in efficiency. Hence, columns with smaller particles can be used at higher linear velocity without sacrificing efficiency for analysis time. This suggests that the particle diameter should be decreased as much as possible to obtain the highest resolution [1], since N is inversely proportional to particle size, N ∞ 1/dp [6], and the resolution is proportional to the square root of N (4.).
4. {Resolution_equation.JPG} [7]
higher peak capacity.capacity in gradient separations.
It is also worth mentioning that efficiency is proportional to column length and inversely proportional to the particle diameter, N ∞ L/dp [6]. In this case, for a given efficiency, the column length can be reduced by the same factor as the particle size to achieve faster separations without sacrificing resolution.
3. Effects of packing materials (porous versus nonporous) and efficiency of particle packing on column Efficiency
20. DOI Kenneth Fountain, Uwe Neue, Eric Grumbach, Diane Diehl (2009), Effects of extra-column band spreading, liquid chromatography system operating pressure, and column temperature on the performance of sub-2-μm porous particles, Journal of Chromatography A, 1216, 5979-5988
21. DOI Sabine Heinisch, Gert Desmet, David Clicq, Jean-Louis Rocca (2008), Kinetic plot equations for evaluating the real performance of the combined used of high temperature and ultra-high pressure in liquid chromatography. Application to commercial instruments and 2.1 and 1mm I.D. columns, Journal of Chromatography A, 1203, p. 124-136
1148, p. 128-130128-13