enow.com Web Search

Search results

  1. Results from the WOW.Com Content Network
  2. Pantograph - Wikipedia

    en.wikipedia.org/wiki/Pantograph

    Drafting pantograph in use Pantograph used for scaling a picture. The red shape is traced and enlarged. Pantograph 3d rendering. A pantograph (from Greek παντ- 'all, every' and γραφ- 'to write', from their original use for copying writing) is a mechanical linkage connected in a manner based on parallelograms so that the movement of one pen, in tracing an image, produces identical ...

  3. Ring expansion and contraction - Wikipedia

    en.wikipedia.org/wiki/Ring_expansion_and_contraction

    Ring opening as a means of ring expansion can also be applied to larger systems to give access to even larger ring syscyclization. The Grob fragmentation can be applied as an example of such an expansion. Like the pinacol type migration the Grob fragmentation relies on an electron donating group to promote the bond migration and encourage the ...

  4. Electroanalytical methods - Wikipedia

    en.wikipedia.org/wiki/Electroanalytical_methods

    A normal experiment may involve 1–10 mL solution with an analyte concentration between 1 and 10 mmol/L. More advanced voltammetric techniques can work with microliter volumes and down to nanomolar concentrations. Chemically modified electrodes are employed for the analysis of organic and inorganic samples.

  5. Ab initio quantum chemistry methods - Wikipedia

    en.wikipedia.org/wiki/Ab_initio_quantum...

    Ab initio means "from first principles" or "from the beginning", implying that the only inputs into an ab initio calculation are physical constants. [5] Ab initio quantum chemistry methods attempt to solve the electronic Schrödinger equation given the positions of the nuclei and the number of electrons in order to yield useful information such ...

  6. Polyhedral skeletal electron pair theory - Wikipedia

    en.wikipedia.org/wiki/Polyhedral_skeletal...

    In chemistry the polyhedral skeletal electron pair theory (PSEPT) provides electron counting rules useful for predicting the structures of clusters such as borane and carborane clusters. The electron counting rules were originally formulated by Kenneth Wade , [ 1 ] and were further developed by others including Michael Mingos ; [ 2 ] they are ...

  7. Coulometry - Wikipedia

    en.wikipedia.org/wiki/Coulometry

    Also called direct coulometry, the analyte is oxidized or reduced at the working electrode without intermediate reactions. [6] The working electrode is kept at a constant potential and the current that flows through the circuit is measured. This constant potential is applied long enough to fully reduce or oxidize all of the electroactive ...

  8. Potentiometric titration - Wikipedia

    en.wikipedia.org/wiki/Potentiometric_titration

    In analytical chemistry, potentiometric titration is a technique similar to direct titration of a redox reaction. It is a useful means of characterizing an acid. No indicator is used; instead the electric potential is measured across the analyte, typically an electrolyte solution.

  9. Probe tip - Wikipedia

    en.wikipedia.org/wiki/Probe_Tip

    This problem can be resolved by taking images of the tip multiple times, followed by combining them into an image by confocal microscope with some fluorescent material coating on the tip. It is also a time-consuming process due to the necessity of monitoring the wear or damage or degradation of the tip by collision with the surface during ...