Specifically programmable-temperature

When GC is being used, possible contamination of the system (injector and column) with nonvolatile polymeric material is the main issue. One option is to allow direct introduction of a polymer-containing sample (solution), but to confine the polymer to a removable part ( hner ) of the injection system. On some injection systems (specifically programmable-temperature vaporizers, or PTVs), a series of injections may be performed before the quantitative analysis of monomer is jeopardized and the liner needs to be replaced. Such an approach may be acceptable if... 

In the on-column technique the sample is introduced directly into the colunrn. The sample must be injected into a cold injector (or any other specific device, e.g., a programmable temperature evaporator), so that the evaporated solvent is retained in the colunrn quantitatively. The injection must be slow enough (say in 10 s) to avoid a (short-term) large solvent vapour carrier gas ratio. The needle of the syringe must reach far enough into the column to avoid escape of sample components into the injector block. As the presence of the needle causes a volume reduction to < 0.5 mL, the pressure of the carrier gas must be high enough to enable the gas to enter the column. 

These events have been modelled [7.33], and a specific programme of in-pile experiments, so-called JOG 1 and JOG 2 tests, have been performed in the CABRI reactor [7.34] for further investigation of some parameters. The thermal conductivity of the JOG material is of particular interest since it is the main input parameter in any fuel-clad gap conductance calculation. Initial results tend to confirm the potential importance of this JOG layer in fuel behaviour at high bum-up its presence may result in a stabilization or even lowering of fuel temperatures and provide a joint with beneficial plastic properties which could ease fuel-clad mechanical interaction effects. 

Plants are constantly subject to adverse environmental conditions such as drought, flooding, extreme temperatures, excessive salts, heavy metals, high-intensity irradiation and infection by pathogenic agents. Because of their immobility, plants have to make necessary metabolic and structural adjustments to cope with the stress conditions. To this end, the expression of the genetic programme in plants is altered by the stress stimuli to induce and/or suppress the production of specific proteins which are either structural proteins or enzymes for specific metabolic pathways. 

The CEA launched in 2001 an integrated programme to compare the most promising way to produce hydrogen using the high temperature heat available from a VHTR. In order to develop its own expertise on thermochemical cycle assessment, CEA has chosen to develop a scientific approach based on data acquisition (development of devoted devices and specific analytical methods) and modelling (physical models, flow sheet analysis, systemic approach). 

Specific conductive silicon substrates have to be carefully prepared before use. For the diamond-deposition process, substrates have to be cleaned, seeded with diamond nanocrystalline seeds at high surface density, and then coated with a grown thick diamond film (from less than 1 pm up to several p,m) by hot filament chemical vapor deposition (HF-CVD). At Adamant, deposition processes are performed automatically in programmable controlled process units, which allow growing diamond on scale up to 0.5 m2. The process is performed under low pressure (1 < 0.1 bar) and high temperature (filament temperature 2,500°C and substrate temperature 800-1,000°C) with a gas mixture composed of CH4, H2 (CH4/H2 ratio <1%), and a boron source (typically trimethyl boron). 

Differential thermal analysis (DTA) is based upon the measurement of the temperature difference (AT) between the sample and an inert reference such as glass or AIjO as they are both subjected to the same heating programme. The temperature of the reference will thus rise at a steady rate determined by its specific heat, and the programmed rate of heating. Similarly with the sample, except that when an exothermic or endothermic process. occurs a peak or trough will be observed. Typical behaviour is shown schematically in Figure 11.7. 

The decomposition of sulfuric acid at 850 900 °C [reaction (4.31)], a component of all the sulfur cycles, places severe specifications on the materials of plant construction due to the extremely corrosive nature of the species at high temperatures. This is one of the major issues that is being addressed by the European HYdrogen THErmochemical Cycles (HYTHEC) programme. The... 

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