Adherents problems encountered

One of the problems encountered in early polyester fibre processing was that the sizes generally used with other classes of fibre to protect yarns, particularly warp yams, against damage during weaving were not sufficiently adherent to the yarn. ICI found a surface treatment that would improve the adhesion of sizes to... 

When the rerun is required due to matrix effects interferences or other problems encountered, the Government will pay the Contractor for the reruns. Such reruns shall be billable and accountable under the specified contract allotment of automatic reruns. When the rerun is required due to Contractor materials, equipment or instrumentation problems or lack of Contractor adherence to specified contract procedures, the rerun shall not be billable nor accountable under the terms of this contract. The Contractor s failure to perform any of the sample reruns specified herein, either billable or nonbillable shall be construed as Contractor nonperformance and may result in the termination of the contract for default. Specific requirements for reextraction and reanalysis are given in Section 17. 

The first problem encountered when studying literature on method validation are the different sets of terminology employed by different authors. A detailed discussion of this problem can be found in the review of Hartmann et al. [9], Therein, it was proposed to adhere, in principle, to the terminology established by the ICH [13], except for accuracy, for which the use of a more detailed definition was recommended (cf. Accuracy). However, the ICH terminology lacked a definition for stability, which is an important parameter in bioanalytical method validation. Furthermore, the ICH definition of selectivity did not take into account interferences that might occur in bioanalysis (e.g. from metabolites). For both parameters, however, reasonable definitions were provided by Conference Report II [10]. 

Problems of desorption and loss of activity encountered with natural heparin have led numerous workers to explore synthetic heparin-like polymers or heparinoids, as reviewed by Gebelein and Murphy [475, 514, 515]. The blood compatibility of 5% blended polyelectrolyte/polyfvinly alcohol) membranes was studied by Aleyamma and Sharma [516,517]. The membranes were modified with synthetic heparinoid polyelectrolytes, and surface properties (platelet adhesion, water contact angle, protein adsorption) and bulk properties such as permeability and mechanical characteristics were evaluated. The blended membrane had a lower tendency to adhere platelets than standard cellulose membranes and were useful as dialysis grade materials. 

Carry-over of volatile silica is generally a problem only at pressures of 1000 psi (68 atm) or above, although it can be encountered at pressures as low as 600 psi (41 atm). For the protection of the turbine, it is important that silica carryover he prevented in this pressure range by adherence to the silica limits of Fig. 7. 

WET PRESSING. Where wet presses have a plain roll in direct contact with the wet paper web, serious difficulties have been encountered, attributed to hydrolysed and poorly retained neutral size residues (22). These are deposited on the surface of the roll, building up a film to which the wet web adheres, causing wrap rounds and web breaks. If no solution can be found, this would be a big enough problem to preclude running neutral/alkaline particular attention needs to be paid to minimising pre-hydrolysis and maximising size retention. 

Not much research was performed on coating of tubes in this project. Results on the coating of commercial tubes show however that it is rather difficult to coat sufficiently defect-free membranes on these supports. As was already stated in chapter 4, the surface roughness of the used tubes was possibly too high to coat high quality silica layers. Another possibility is that here the same problem occurs as was encountered with the sealed flat membranes. Some defects in the membrane layer might result from a bad adherence of the coated layer at the enamel/membrane interface. 

In the present state of the art of polymer physics, an exhaustive solution of the first of these two problems has not been found so far, although some attempts in this direction have been undertaken. At the same time, an intensive development of production of polymers puts forward demands of the prediction of their properties. To cope with this task chemical engineers generally use in practice some simple semi-empirical correlations. In doing so, they resort to certain qualitative theoretical approaches to treat the available experimental data. According to the most reputable adherent of this method, van Krevelen, such semi-empiri-cal correlations are highly effective and provide rather reliable results in most practically important cases (van Krevelen and te Nijenhuis, 2009). However, even in the framework of the above approach, considerable difficulties are encountered, because often there is no clear idea about which specific statistical characteristics of a polymer are responsible for a particular mechanical and physicochemical property. It especially concerns copolymers because the number of their characteristics of such a kind is larger than that for homopolymers. 

Compliance to treatment is defined as adherence to treatment by the patient, as prescribed by the physician. Various causes of noncompliance may be identified (1) patient-related causes, e.g., the patient does not understand the processes behind the disease or the aim of the treatment, a problem that might be more specifically encountered with inhaled glucocorticosteroids than with p -agonists, as the immediate effects of inhaled corticosteroids are not perceived (2) inhaler-related causes, e.g., inhalers that are impractical, not portable, or difficult to use (3) financial causes, e.g., insufficient reimbursement of the treatment, an issue that may vary from one country to another. 

The names of many polymers are based on the monomers from which they were prepared. There is, however, frequent variation in the format. A nomenclature of polymers was reconunended by lUPAC and is used in some publications. Strict adherence to the recommendation, however, is mainly found in reference wor. Also, problems are often encountered with complex polymeric structures that are crosslinked or have branches. In addition some polymers derive their names from trade names. For instance, a large family of polyamides is known as nylons. When more than one functional group is present in the structure, the material may be called according to all functional groups in the structure. An example is a polyesteramide. A thermoset polymer prepared from two different materials may be called by both names. For instance, a condensation product of melamine and formaldehyde is called melamine-formaldehyde polymer. 

Treating the wall of the column is critical because it helps the synthesized polymer to adhere to it. This is done by treating the wall with a monomer that binds with the mixture of monomers used in making the monolith. This step is important because it enables the monolith to adhere to the wall of the mold and void any space that may be created. Since this polymerization is an in situ process, it avoids the problem of cladding that is encountered in silica-based monohths. 

With sliding doors or conveyor belts sliding on support surfaces different type of low friction or low drag application is encountered. The normal forces are generally small and the faction load problems are of the adhering type. Some plastics exhibit excellent surfaces for this type of application. PTFEs (tetrafluoroethylene) have the lowest coefficient of any solid material and represent one of the most slippery surfaces known. The major problem with PTFE is that its abrasion resistance is low so that most of the applications utilize filled compositions with ceramic filler materials to improve the abrasion resistance. 

At this point we are in a position to understand why physicists resolutely adhere to Newton s three laws of mechanics while engineers always adopt some form of Euler s two laws. The physicist, with an overriding Interest in the motion of particles, finds it convenient to tacitly accept the central force law in the discussion of non-relativlstic mechanics since this idea is easily altered when relativistic problems are encountered. If the physicist were to adopt Euler s two axioms of mechanics, the second axiom would require alteration when relativistic problems arise. Engineers, on the other hand, are immersed in the study of continua and Euler s laws for linear and angular momentum are perfectly suited to their purposes which rarely include relativistic effects. 

The problem of lamellar structures like 2H-M0S2 and 2H-WS2 is the easy oxidation at the edges of crystals. These structures easily adhere to surfaces, while fullerenes do not, as Rapoport et al. showed using surface force microscopy (SFM). IFs are swept by the tip in the contact image mode, which proves their weak adhesion on a surface [41]. In the case of porous matrices, platelets are perpendicular to the surface involving their rapid deterioration during friction, whereas the fullerenes enter into the asperities, which act as reservoirs [42]. The spherical structure of the IF avoids problems of orientation encountered with 2H platelets [43]. 

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