Databases Reference
In-Depth Information
analyses. For more information on Origin C and Labtalk syntax, the reader is encouraged to make
use of the following freely available resources on the World Wide Web:
http://www.originlab.com/
http://g.webring.com/hub?ring=originwebring
Excel has two principal methods that can be utilized to harness the Origin computational engine.
The first, DDE, will be covered briefly. Although DDE is no longer supported by Microsoft, it is
still widely utilized. DDE remains extremely useful, especially when a method is required to perform
a quick computation utilizing the Origin computational engine, and return only a number as opposed
to returning a result and other ancillary information such as a graph. The second method requires
utilizing an Automation Server. This approach utilizes the most current techniques and allows any
client application (such as Microsoft Excel) to make calls to Origin, perform analyses, and return
pertinent information such as fitted data, graphs, etc.
A typical Excel client application might involve some or all of the following actions:
1.
Launching an instance of the Origin application.
2.
Opening a previously created Origin template.
3.
Sending data from an external source (the client) to Origin (the server) for analysis.
4.
Sending Origin specific commands to analyze the data.
5.
Requesting the processed results from Origin.
6.
Returning images of graphs prepared in the Origin analysis.
7.
Saving the results generated by the Origin project.
8.
Closing the instance of the Origin application.
This list encompasses a wide range of processes and actions and is fairly comprehensive in
terms of application to application interaction. In order to effectively demonstrate using DDE and
Automation Server Technologies with Excel, a fairly complicated example will need to be constructed
for the reader. The reader will be shown how to calculate pKa values for one and two pKa systems
utilizing the Origin computational engine.
A pKa (also termed the Dissociation Constant), is a measure of the strength of an acid or a
base. A pKa determination shows the charge on a molecule at any given pH (Figure 9.18). A pKa
value is often useful in predicting if a specific compound does or does not have drug-like properties.
Compounds screened in drug discovery settings typically have pKa values from 3 to 12.
To accomplish pKa curve fitting in Origin for Excel, a number of tasks must be completed.
They are as follows in order of increasing complexity:
1.
A Origin Worksheet template must be constructed.
2.
pKa Curve Fitting functions must be defined in Origin.
10
0
10
-7
10
-14
Small
intestine
Stomach
Blood
0
1
2
3
4
56
7
8
9
10
11
12
13
14
Battery
acid
Vinegar Orange
juice
Milk
Sea water
Bleach
FIGURE 9.18
Relative pH scale indicators.
