Atmosphere dynamic/static

All of the monoliths produced were dried at 150°C and fractions subsequently heat-treated at either 500°C or 850°C in a nitrogen atmosphere. The static and dynamic adsorption capacities of these monolithic composites at 30°C were determined using o-DCB as a probe molecule. This molecule was chosen since it may be considered as approximately corresponding to half a molecule of tetrachloro-dibenzene dioxin (TCDD), the most toxic isomer of the dioxin family. 

Some workers have experimented with oxidation under static conditions. According to Rezl and Janak [12], good results can be obtained by combining the static and dynamic methods. They recommend that the chemical decomposition should take place in an inert atmosphere under static conditions and that the sample should have a layer of a catalyst on it final oxidation takes place in a flow-through reactor in a layer of oxidation catalyst. 

Identification of the sample atmosphere by pressure, composition, and purity whether the atmosphere is static, self-generated, or dynamic through or over the sample. Where applicable, the ambient atmospheric pressure and humidity should be specified. If the pressure is other than atmospheric, full details of the method of control should be given. 

A) Static or dynamic atmosphere. Under static conditions, gaseous products cannot be removed rapidly from the vicinity of the sample. This leads to a partial pressure of the products and the reaction temperature is increased. Under dynamic or flowing conditions, evolved gases can be removed from the vicinity of the sample, and the partial pressure of the products decreases. 

Other than static and dynamic deposition methods, researchers also tried dynamic-static deposition method (Baowei et al. 2012). In this method, dynamic deposition occurred when a PDADMAC solution was used. However, the PSS solution flowed over the membrane surface at atmospheric pressure (no PSS solution permeated through the UF membrane). This method actually combined both the dynamic and static deposition methods during the deposition of each polyelectrolyte layer using a cross-flow unit. 

The LC/TOF instmment was designed specifically for use with the effluent flowing from LC columns, but it can be used also with static solutions. The initial problem with either of these inlets revolves around how to remove the solvent without affecting the substrate (solute) dissolved in it. Without this step, upon ionization, the large excess of ionized solvent molecules would make it difficult if not impossible to observe ions due only to the substrate. Combined inlet/ionization systems are ideal for this purpose. For example, dynamic fast-atom bombardment (FAB), plas-maspray, thermospray, atmospheric-pressure chemical ionization (APCI), and electrospray (ES)... 

Equilibrium moisture content of a hygroscopic material may be determined in a number of ways, the only requirement being a source of constant-temperature and constant-humidity air. Determination may be made under static or dynamic conditions, although the latter case is preferred. A simple static procedure is to place a number of samples in ordinaiy laboratoiy desiccators containing sulfuric acid solutions of known concentrations which produce atmospheres of known relative humidity. The sample in each desiccator is weighed periodically until a constant weight is obtained. Moisture content at this final weight represents the equilibrium moisture content for the particular conditions. 

Gravity, applied forces, and atmospheric pressure are examples of static factors that apply equally to fluids at rest or in motion. Inertia and friction are dynamic forces that apply only to fluids in motion. The mathematical sum of gravity, applied forces, and atmospheric pressure is the static pressure obtained at any one point in a fluid system at a given point in time. Static pressure exists in addition to any dynamic factors that may also be present at the same time. 

Since ozone attack on rubber is essentially a surface phenomenon, the test methods involve exposure of the rubber samples under static and/or dynamic strain, in a closed chamber at a constant temperature, to an atmosphere containing a given concentration of ozone. Cured test pieces are examined periodically for cracking. 

In OIT determinations, the test samples are flushed continuously with oxygen during the course of the measurement [1], This is in contrast to oxygen-uptake measurements that are mostly undertaken in a static oxygen atmosphere (see below). Effects such as dynamic removal of volatile antioxidants in the OIT method can lead to these two methods yielding very different assessments of a polymer formulation s stability [1]. 

It must be also considered that the reaction rates of different thermal processes which can occur simultaneously are influenced by the treatment conditions (temperature, heating rate, pressure, static or dynamic atmosphere). This will affect the relative quantities of the products formed and in some cases also their nature, when recombination reactions give rise to secondary degradation products. On account of its sensitivity and resolution power Py-GC/MS will also provide useful information on minor components present in a material, including low molecular weight additives and pigments. 

The ionic atmosphere moves continually, so we consider its composition statistically. Crystallization of solutions would occur if the ionic charges were static, but association and subsequent dissociation occur all the time in a dynamic process, so even the ions in a dilute solution form a three-dimensional structure similar to that in a solid s repeat lattice. Thermal vibrations free the ions by shaking apart the momentary interactions. 

Depending on meteorologic conditions, aerosol formation in the atmosphere is better approximated, but never fully simulated, by smog-chamber studies under either static (batch-reactor) or dynamic (flow-reactor) conditions. 

Several test atmosphere generating systems have been reported (1-6), Basic principles and techniques employed have been discussed in detail by Nelson (7). The methods are generally divided into two catagories static methods and dynamic methods. 

Figure 4. Weathering conditions for glass static weathering (left) time, long SA/V, extremely high reaction (2) >> reaction (1) and dynamic weathering (right) atmospheric reactions significant reaction (1) > > reaction (2).

The nanostructure of a solid, also referred to in terms such as "defects," "real structure," and "mosaic structure," depends strongly on its environment. As all aspects of the nanostructure may be relevant to catalytic functions, it is common to infer such properties from static determinations of the nanostructure, often carried out at about 300 K and in laboratory or autogeneous atmospheres. This approach neglects the dynamics and assumes incorrectly that the surface catalysis process should not modify the rigid crystalline bulk of a solid. 

XAS can be used in several different ways to determine local structural information about catalysts in reactive atmospheres. This structural information may be static or dynamic it may be geometric or electronic. The depth of information that can be ascertained is often dependent upon the type of catalyst, for example, supported metal nanoclusters versus bulk or surface oxides. It may also be controlled by some property of the catalyst, for example, the concentration of the element in the catalyst that is being investigated. In this section a few examples are provided to highlight the importance and relevance of XAFS in catalyst characterization. The examples are focused on (1) structural information characterizing samples in reactive atmospheres, (2) transformation of one species to another, (3) oxidation state determination, (4) determination of supported metal cluster size and shape, and (5) electronic structure. These examples illustrate the type of information that can be learned about the catalyst from XAFS spectroscopy. 

Regarding the overpressure test, an overpressure of 1.5 times the reference pressure is required by the d-standards, with a minimum of 3.5 bar (referring to atmospheric pressure). This test may be a static test using a liquid (oil, water) or compressed air (in this case, to avoid parts of an enclosure which fails becoming dangerous projectiles, the overpressure test shall be made with a barrier - e.g. within a closed testing vessel) or a dynamic test based upon the same procedure as described for the determination of the reference... 

At present, when working with high-purity materials, smooth solid surfaces and low P02 atmospheres, the thermodynamic contact angle in a particular system can be determined at best within about five degrees. Roughness must be very low, particularly in non-wetting systems in order to obtain such an accuracy. The control of P02 is critical for oxidisable liquids and solids, specially at relatively low temperatures, and dynamic vacuum is often preferable to a static neutral gas atmosphere. 

When experiments are performed in a static neutral gas atmosphere, deoxidation depends on diffusion of volatile species into the gas. For the same temperature and P02 values, deoxidation takes longer in such atmospheres than in a high vacuum but some acceleration can be achieved by using dynamic conditions i.e., gas flow (Ricci et al. 1994). 

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