Short spacing

On investigating a new system, cyclic voltannnetty is often the teclmique of choice, since a number of qualitative experiments can be carried out in a short space of time to gain a feelmg for the processes involved. It essentially pennits an electrochemical spectrum, indicating potentials at which processes occur. In particular, it is a powerfid method for the investigation of coupled chemical reactions in the initial identification of mechanisms and of intemiediates fomied. Theoretical treatment for the application of this teclmique extends to many types of coupled mechanisms. 

A second form of desolvation chamber relies on diffusion of small vapor molecules through pores in a Teflon membrane in preference to the much larger droplets (molecular agglomerations), which are held back. These devices have proved popular with thermospray and ultrasonic nebulizers, both of which produce large quantities of solvent and droplets in a short space of time. Bundles of heated hollow polyimide or Naflon fibers have been introduced as short, high-surface-area membranes for efficient desolvation. 

The major advantage of array detectors over point ion detectors lies in their ability to measure a range of m/z values and the corresponding ion abundances all at one time, rather than sequentially. For example, suppose it takes 10 msec to measure one m/z value and the associated number of ions (abundance). To measure 100 such ions sequentially with a point ion detector would necessitate 1000 msec (1 sec) for the array detector, the time is still 10 msec because all ions arrive at the same time. Therefore, when it is important to be able to measure a range of ion m/z values in a short space of time, the array detector is advantageous. 

An array ion collector (detector) consists of a large number of miniature electron multiplier elements arranged side by side along a plane. Point ion collectors gather and detect ions sequentially (all ions are focused at one point one after another), but array collectors gather and detect all ions simultaneously (all ions are focused onto the array elements at the same time). Array detectors are particularly useful for situations in which ionization occurs within a very short space of time, as with some ionization sources, or in which only trace quantities of a substance are available. For these very short time scales, only the array collector can measure a whole spectrum or part of a spectrum satisfactorily in the time available. 

Some of the target molecules gain so much excess internal energy in a short space of time that they lose an electron and become ions. These are the molecular cation-radicals found in mass spectrometry by the direct absorption of radiation. However, these initial ions may react with accompanying neutral molecules, as in chemical ionization, to produce protonated molecules. 

A laser beam is capable of putting so much energy into a substance in a very short space of time that the substance rapidly expands and volatilizes. The resulting explosive shock wave travels through the sample, subjecting it to high temperatures and pressures for short times. This process is also known as ablation. 

A variety of military aircraft projects have occurred over the years — far more than can be summarized in a short space here. Thus, only some of the significant milestones will be described. 

In 1854, the Manchester Steam Users Association was formed to help with the prevention of explosions in steam boilers and to find efficient methods in their use. To achieve this, the Association employed the first boiler inspectors, whose services were then made available to the Association s members. Within a short space of time, the members became convinced that insurance to cover the high cost of repair or replacement of damaged boilers was desirable, and this resulted in the first boiler insurance company (The Steam Boiler Assurance Company) being formed in 1858. The scope of the services for inspection and insurance later extended to include pressure vessels, steam engines, cranes, lifts and electrical plant, the insurance protection in each case being supported by an inspection service carried out by qualified engineer surveyors. 

Within a very short space of time—perhaps only the last 5 years, there has been an explosion of interest in electronic laboratory notebook systems in general, and particularly within the drug discovery community. In large part... 

While in this short space we have barely touched upon the salient features of this reaction, we hope it has been sufficient to wet the readers appetite to pursue the subject in more detail. This new approach to studying catalytic reactions is opening up major new avenues for their understanding. 

Aurum Potabile. An Admonition. An instruction and proof against all those who falsely persuade and propose both to themselves and to others to prepare for them in a short space of time an Aurum potabile, without the process and... 

It is inappropriate in this survey to attempt to summarise in a short space the results of all the above treatments, but virtually all the calculations indicate that in M(Cp)2 species the 7r(ej) metal-ligand interaction is dominant in the metal to ring bonding. However, debate has largely been concentrated on two points, in the first place the extent of the validity (or otherwise) of Koopmans theorem, and, further, the question of the correct energetic ordering (5 < o < n or o < 5 < n) of the mainly metal tf-type orbitals. 

The investigations described in the preceding pages have been directed to one point Only the exact determination of the excess of dissolved substance in the surface layer at one particular concentration. There are, however, some further questions of great importance, the answers to which must be sought by other experimental methods. The first of these is does adsorption lead to a well-defined equilibrium in a short space of time the second is this equilibrium, assuming it to exist, a simple function of the concentration ... 

Presently, by the movement of her lips he would know she was praying for the absent one. He would lay aside his pipe, fetch his beads, and together they would say the Rosary, begging the blessed Mother of God to keep special watch over their child. She was the only one they had left, four little white stones marking the resting-place of the four little angels who had been permitted to remain with them for only such a very short space of time. 

Alchemy was in many respects eminently suitable as a cloak for ftaud, and those who became "alchemists" with the sole object of accumulating much wealth in a short space of time, finding that the legitimate pursuit of the Art did not enable them to realise their expectations in this direction, availed themselves of this fact. There is, indeed, some evidence that the degeneracy of Alchemy had commenced as early as the fourteenth century, but the attainment of the magnum opus was regarded as possible for some three or more centuries. 

Fenn published work in 1989 [7-9] showing ionisation of large molecules by electrospray ionisation (ESI). Fenn built on the early work of Malcolm Dole [10] but Fenn used a counter current gas to assist with desolvation of the droplets and aid the formation of the ions. In the early 1990s, experiments with atmospheric pressure ionisation (API) showed promise and in a short space of time the first commercial systems utilising the new techniques of ESI [11] and Atmospheric Pressure Chemical Ionisation (APCI) began to appear on analysts benches. The sensitive, reliable and easily operated LC-MS system had arrived. 

If we assume current world production of all rare earths to be of the order of 35,000 tons per year, expressed as rare earth oxide, then approximately 17o of this total, equating to about 230 tons, represents the current level of production of pure metals. While in itself this figure may appear insignificant, it is necessary to view it in the light of two other factors. First, expressed in monetary terms the 17o equates to nearer 1% of total value and secondly, over the past 3 years demand for pure metals has been increasing at a rate approaching 20% per year which, if sustained, could radically change the face of the industry within a short space of time.(l )... 

---