Glossary of terms

Adsorption It relates to the adherence of ions, molecules or particles with the membrane surfaces in contact (internal and external). In CFF this phenomenon could reduce the flux or change the retention characteristics. The tendency to form an adsorbed layer on the membrane surface may depend on the nature of the membrane surface. Typically hydrophilic surfaces adsorb less strongly than the hydrophobic surfaces, especially when organics are involved. 

Asymmetric/composite membrane This typically consist of a thin (0.5 to 20 microns) fine-pore layer responsible for separation and a support or substrate with single or multiple layers having progressively larger pores which provide the required mechanical strength. This type of structure maximizes the flux by minimizing the overall hydraulic resistance of the permeate (filtrate) flowing across the membrane structure. 

Backpressure It is the pressure generated by restricting retentate flow. 

Backpulse This is achieved by rapid (typically lasting a fraction of a second) application of periodic counterpressure on the permeate side, typically with the help of an automatic time switch or a microprocessor, to push back a specific (as low as possible) permeate volume in the opposite direction. It is used in many CFF applications (especially with ceramic membranes) as an effective technique to disrupt, reduce or destroy the concentration-polarization boundary layer. Backpulsing also helps to minimize particle/gel infiltration into the microporous structure. Typical backpulse frequencies (cycle times) are in the range of 3 to 10 minute.  

Backwash This is similar to the backpulse technique but is less intensive in terms of the pressures applied across the membrane to dislodge particles/gels from the membrane surface. Backpulse is typically carried out at pressures exceeding 4 bar and often in the range 6 to 10 bar, whereas a backwash is carried out at lower pressures (e.g., 2 to 3 bar). 

Ab initio- iist principles quantum mechanical a pproach for obtaining the electronic properties of a molecule based on the approxiniate solutions to the many-electron Schrodinge r equation, using only fundamental constants, and the mass and charge of the nuclear particles literally from the beginning . 

Basis function-functions describing the atomic orbitals that when linearly combined make up the set of molecular orbitals in a quantum mechanics calculation Gaussian basis sets and Slater type orbitals are examples of basis functions. 

Bom-Oppenheimer approximation-A method for separating electronic motion from that of the nuclei in quantum mechanics the nuclei having greater mass are assumed stationary while the electrons are moving around therrr. 

Buckingham potential-f imction irsed for describing the ene rgy of the Coirlombic and short-range interactions of ionic or partially-ionic compounds incorporates a two-parameter exponential and one-parameter dispersion term. 

Correlation energy-The difference between the experimental energy and the Hartree-Fock energy in quantum mechanics related to the neglect of local distortion in the distribution of electrons in the calculation. 

The terms below have been adopted or adapted from existing definitions for use in the context of human exposure assessment. Definitions of additional terms used in this document may be found in the IPCS risk assessment terminology Harmonization Project Document (IPCS, 2004). 

Degree of agreement between average predictions of a model or the average of measurements and the true value of the quantity being predicted or measured. Accuracy is also a criterion used to evaluate the knowledge base uncertainty. It focuses on the identification of the most important bottlenecks in the available knowledge and the determination of their impact on the quality of the result. 

Aleatory is of or pertaining to natural or accidental causes and cannot be explained with mechanistic theory. Generally interpreted to be the same as stochastic variability. 

A characteristic of the uncertainty. It is used for qualitative characterization of the source of uncertainty. The appraisal of the knowledge base focuses on the adequacy of the available knowledge base for the exposure assessment (e.g. identification of data gaps and their impact on outcome). 

Also referred to as systematic error. Difference between the mean of a model prediction or of a set of measurements and the true value of the quantity being predicted or measured. 

Additive A substance added to petroleum mixtures (e.g. oxygen- 

Alkanes are arranged in open chains (that might include branches). The term includes paraffins and olefins and provides a distinction from aromatics and naphthenes, which have at least some of their carbon atoms arranged in closed chains or rings. Hydrocarbons that contain only single carbon-carbon bonds. The chemical name indicates the number of carbon atoms and ends with the suffix -ane. 

Alkenes Hydrocarbons that contain carbon-carbon double bonds. The chemical name indicates the number of 

Alkyl groups A group of carbon and hydrogen atoms that branch 

Alkyne from the main carbon chain or ring in a hydrocarbon molecule. The simplest alkyl group, a methyl group, is a carbon atom attached to three hydrogen atoms. Hydrocarbons that contain carbon-carbon triple bonds. 

The following list has been made with reference to Murrill [1], 

Portion of the valve that may be pneumatic or motor driven, used to open and close automatic valves. 

The difference between the average value of a sinusoidal variation and the maximum or minimum value. 

The ratio of the amplitude of a system s response to its forcing function s amplitude when the forcing function is a continuous sinusoid a form of dynamic gain. 

A controller that operates on continuous signals such as voltages, pressures, or currents this is a common older type of controller, as distinguished from a digital controller. 

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The April 1988 issue of the Journal of Chemical Education contains a number of articles on polymers including a historical review enti tied Polymers Are Everywhere (pp 327-334) and a glossary of terms (pp 314-319)... 

Provides a glossary of terms that explains the acronyms used in mass spectrometry Includes over 3QQ figures and tables... 

A number of glossaries of terms and symbols used in the several branches of chemistry have been pubHshed. They include physical chemistry (102), physical—organic chemistry (103), and chemical terminology (other than nomenclature) treated in its entirety (104). lUPAC has also issued recommendations in the fields of analytical chemistry (105), coUoid and surface chemistry (106), ion exchange (107), and spectroscopy (108), among others. 

WIPO, "Glossary of Terms Concerning Industrial Property Information and Documentation," WorldPat. Inf. 15, 21—39 (1993). 

Glossary of Terms Relating to Rubber and Rubber Technology, American Society for Testing and Materials, Philadelphia, Pa., 1972. 

Glossary of terms associated with fire. Part 6 Evacuation and means of escape. Superseded BS 4422 Part 3 1972... 

Withdrawn) 1988 Glossary of terms for personal eye-protection. Withdrawn, superseded by BS EN 165 1996... 

Glossary of Terms. Test Methods for Pressure Sensitive Adhesive Tapes, Pressure Sensitive Tape Council, 1996. 

To use the volume effectively, the reader should first review the Glossary of Terms section immediately preceding the first chemical entry. This section contains precise definitions used for certain parameters where data have been obtained for each chemical. A review of these terms will help the reader interpret certain information. In addition, a list of abbreviations used throughout the volume is also provided in the front section of the handbook. 

Fluorinated rubbers, copolymers of hexafluoropropylene and vinylidene-fluorides, have excellent resistance to oils, fuels and lubricants at temperatures up to 200°C. They have better resistance to aliphatic, aromatic and chlorinated hydrocarbons and most mineral acids than other rubbers, but their high cost restricts their engineering applications. Cheremisinoff et al. [54] provide extensive physical and mechanical properties data on engineering plastics. A glossary of terms concerned with fabrication and properties of plastics is given in the last section of this chapter. 

References are located on pages 92-95. A glossary of terms appears on pages 96-98. 

Produce a glossary of terms covering the concepts, documents, and activities to be used in developing and implementing the quality system. 

Do publish a glossary of terms to those involved before you commence procedure preparation. 

The glossary of terms used in directional drilling [131] has been developed by... 

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