Primary regions, comparison

In Secondary Ion Mass Spectrometry (SIMS), a solid specimen, placed in a vacuum, is bombarded with a narrow beam of ions, called primary ions, that are suffi-ciendy energedc to cause ejection (sputtering) of atoms and small clusters of atoms from the bombarded region. Some of the atoms and atomic clusters are ejected as ions, called secondary ions. The secondary ions are subsequently accelerated into a mass spectrometer, where they are separated according to their mass-to-charge ratio and counted. The relative quantities of the measured secondary ions are converted to concentrations, by comparison with standards, to reveal the composition and trace impurity content of the specimen as a function of sputtering dme (depth). 

Comparison with other Studies. How do the results of our investigation compare with similar studies Our results corroborate the data provided in a similar study of the effect of UV-B on primary productivity in the southeastern Pacific Ocean (35). In the latter study, it was noted that enhanced UV-B radiation caused significant decreases in the productivity of surface and deep samples. Compared to ambient, primary productivity decreased with increasing doses of UV-B. In another study in which in situ experiments using natural Antarctic phytoplankton populations, it was noted that incident solar radiation significantly depressed photosynthetic rates in the upper 10-15 meters of the water column (36). It was also found that the spectral region between 305 and 350 nm was responsible for approximately 75 percent of the overall inhibitory effect. 

The primary structures of CENP-A proteins are surprisingly variable in evolution in comparison to conventional H3. The C-terminal region shows the greatest... 

In the extracellular region, the concentration is over lO M, which is very high in comparison to the free cytosolic Ca concentration. The cell membrane contains various channels that enable Ca influx from the extracellular region into the cytosol. One of the primary functions of Ca entry is to charge up the internal stores, which can then release an internal Ca signal. 

Figure 3.11 Schematic of a time-of-flight mass analyzer with reflectron proposed by Mamyrin,11 Ions of higher kinetic energy penetrate more deeply into the reflecting field and are delayed in comparison to ions of lower kinetic energy. The delay compensates for differences in transit time of the field-free regions. Ions produced e.g., by focused laser or primary ion beam.

When the goal is the production of fine particles it is important to save the primary size of the crystals as they appear first in the solution, i.e. the nucleation has to be promoted over the growth and aggregation steps. In the case of undersaturated, weak initial solutions the precipitation takes place near the metastable region where the kinetic processes are rather slow. For example, the induction time which was necessary for crystallization in the weakest NaCl solutions approaches to 60 min. Repeating the precipitation (where the ethanol content was the same 99.6%) with saturated aqueous solution there was no measurable induction time and the particle size changed considerably within the applied 60 min operational time the d was 4.41 p,m after 10 min, 8.86 pm at 20 min and finally 16.27 pm at 60 min. It is obvious that in the latter case not the smallest available size was measured after 60 min, but for the sake of comparison the same operational time had to be applied. 

---