Control of time

P. Rivers-Moore, "Environmental Control of Time Plants and Quarries in S. Africa," 4th International Time Congress Proceedings, Hershey, Pa., 1978. 

A novel basic support and catalyst have been prepared by activation of aluminium phosphate with ammonia. Fine control of time and temperature allows to adjust the 0/N ratio of these oxynitride solids and thus to tune the acid-base properties. The aluminophosphate oxynitrides are active in Knoevenagel condensation, but a basicity range can not yet determined. Supporting Pt or Pt/Sn on AlPONs allows to prepare catalysts that are highly active and selective in dehydrogenation reactions. 

However, it is not necessary to continue an extraction by SPME until equilibrium is reached. A quantitative result may be achieved by careful control of time and temperature. Ulrich [130] notes that important kinetic considerations of the relationship between analyte concentration and time by SPME include ... 

Present results suggest that most of the silica slurry abrasives can be kept in dispersion by maintaining a RMFV value of 0.5ft/s, whereas alumina and ceria slurries require 1.5 to 2.5ft/s, depending on abrasive and chemical composition of the slurry. Next generation slurry delivery systems should be able to measure and control abrasive particle and chemical characteristics (to ensure mix accuracy and control of time sensitive components such as hydrogen peroxide, ammonium hydroxide, etc.) of the slurry on a real-time basis and consistently provide good slurry at the CMP tools. 

In multideterminations, and also when the target volatile analytes possess different boiling points, the pervaporation unit can be used at different temperatures to ensure selective separation of the species of interest. Use of a heating system allowing reproducible control of time and temperature is obviously mandatory here. 

In unconfined pre-expansion the translucent beads grow larger and become white in color. Confined and subjected to heat, the preexpanded beads can produce a smooth-skinned closed-cell foam of controlled density, registering every detail of an intricate mold. To minimize formation of a density gradient and to ensure uniform expansion throughout the molded piece, expandable-polystyrene beads are preexpanded to the approximate required density by control of time and temperature, since the process of molding does not increase the density (6). 

Automated Procedures Some of the difficulties associated with manual procedures can be eliminated with an automated headspace sampler. Such a device has been described in the literature (14), and is commercially available. The schematic diagram of such a semi-automatic headspace analyzer is shown in Figure 3. Precise control of times and temperatures, as well as the capability to hold samples at high temperatures, produces better chromatographic reproducibility. We have been able to analyze ppm levels of ethyl dodecanoate in aqueous solution with this system. Significant amounts of water vapor are introduced into the gas chromatographic column under these conditions. For this reason, columns with non-polar liquid phases or bonded Carbowax-type liquid phases... 

Since production of Zousoon is rather an empirical process and suffers from lack of control of time and temperature, a study was undertaken by... 

Major disadvantages Control of time and place of polymerization depends on many factors such as... 

Comparison with Equation (3.33) shows that an additional function has been introduced, i.e. (1 + aT s). This introduces a lag into the controller (of time constant aTj) that is intended to reduce the amplification of measurement noise by the derivative action. Setting a to zero removes this filter, setting it to 1 will completely disable the derivative action. In some systems the value of a is configurable by the engineer. In many it is fixed, often at a value of 0.1. The reciprocal of a is known as the derivative gain limit. 

The CIM disks, with low-volume monolith stationary phase, used in this application allowed the desired separation of the analyte under low-pressure conditions. The use of a mixing chamber and the precise control of timing allowed the inline preparation of the necessary high number of standard solution mixtures for the multivariate calibration. The mixing chamber also provided a homogeneous mixture before the transport to the detector. The large sampled volume (1 mL) allowed the recording of spectra without dispersion effects (D = 1). Samples were diluted and their pH was adjusted to 8.5 before injection. Nevertheless, validation for the tartaric acid concentration was not possible with the enzymatic kits used in this work. 

Silicone polyethers are important nonionic surfactants that are also used in cosmetics and household chemistry. However, their most important application is the manufacture of polyurethane foams, both rigid and flexible ones. There are no substitutes for them and their role eonsists in the facilitation of mixing of foam components. They prevent from the formation of large bubbles, facilitate the control of fluidity of liquid mixture (that expands due to the bubble growth), and they enable accurate control of time and degree of foam opening. 

The constant reminder and control of time is highly demotivating... 

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