Databases incompatibilities

Information access breakdowns occur when pertinent information has been stored but it either cannot be accessed for technical reasons or for some reason cannot be found in a meaningful or expedient manner for a particular application. Technical reasons can include legacy databases that are not connected with current systems, incompatibility issues between systems, problems of localized access (information can only be accessed within a site, a group or domain area, or even a personal computer), and authentication (people do not have the required authority to access information they need or cannot remember usernames and passwords). 

The current distribution of geochemical data available through the national repository (OZCHEM database) is shown in Figure 1. The map shows that there are vast areas of the country (>60%) that lack any geochemical information. Also, where geochemical data are available, they are often not comparable as a result of incompatible sampling media, inconsistent sample preparation and analysis methods, incomplete quality assessment metadata and/or different analyte suites being reported. 

If chemical-specific information is not available, the consequences may be able to be predicted by methods using compatibility groups, or chemicals with similar chemical structures that are expected to have similar chemical reactivity characteristics. One computerized tool that uses this approach is the Chemical Reactivity Worksheet made available by the U.S. National Oceanic and Atmospheric Administration (NOAA 2002). This program has over 6000 chemicals, mixtures, and solutions included in its database. It also predicts chemical reaction consequences of combining two materials at a time (e.g., "Heat generation by chemical reaction, may cause pressurization"). Examples from the Chemical Reactivity Worksheet are shown in Section 4.2. It is critical that all chemicals be positively identified to have a complete evaluation of all potential incompatibilities. 

Responses to the CSB industry survey50 indicate that most companies consult a variety of information sources as a first step in compiling data on reactive hazards. However, respondents prefer literature sources and expert opinion over computerized tools such as CHETAH, The Chemical Reactivity Worksheet, or Bretherick s Database of Reactive Chemical Hazards. Such programs can be used to predict the thermal stability of compounds, reaction mixtures, or potential chemical incompatibilities. In some cases, they provide an efficient means of identifying reactive hazards without having to conduct chemical testing. Survey responses showed that five of nine companies consider computer-based tools not valuable. Only two of the surveyed companies use The Chemical Reactivity Worksheet.51... 

In terms of more conventional modelling it is surprising to find that there is still incompatibility between databases that handle complex metallic materials and slags. Sound databases exist for both separately but as yet there is no major integrated database that can handle the very important area of overlap. In terms of a total materials modelling capability it is clearly of benefit to have one self-consistent database rather than a series of separate ones to span a greater range of applications. 

The standards issue is somewhat contentious in this held for several reasons. First, only in the last few years has it been recognized that standards for pathway representation are important, and becoming more so with each passing year. Second, several established databases with incompatible representations have served as de facto standards for a number of years. Third, the entry of commercial vendors into the held has upped the ante, making market compehhon a factor. 

Chapter 2 addresses chemical incompatibility, however most referenced information addresses binary combinations. A comprehensive database of chemical incompatibility, including multiple combinations, would be useful. 

The ion-interaction model is a theoretically based approach that uses empirical data to account for complexing and ion pair formation by describing this change in free ion activity with a series of experimentally defined virial coefficients. Several philosophical difficulties have resulted from the introduction of this approach the lack of extensive experimental database for trace constituents or redox couples, incompatibility with the classical ion pairing model, the constant effort required to retrofit solubility data as the number of components in the model expand using the same historical fitting procedures, and the incompatibility of comparing thermodynamic solubility products obtained from model fits as opposed to solubility products obtained by other methods. 

For solution compositions in which the virial coefficients are well defined, the mineral phase boundaries, ionic activity, and the activity of water, can be modeled remarkably well. Numerous applications are already benefiting from the existing database, such as the ability to predict the solubility of minerals in brine environments. Despite the advancement in the description of high ionic strength solutions, the incompatibility of the ion-pairing model and the semi-empirical... 

S. Hyphae of a het-s strain can fuse with another het-s strain, but not with a strain (Fig. 8). The /tet-5 locus encodes a 289 residue protein with no similarity to other proteins in the database (Turcq et al, 1991 Turcq et al, 1990). The difference between het-s and het-S is 14 amino acids, with the residue 33 difference critical to produce the heterokaryon incompatibility reaction (Deleu et al, 1993). 

Reliability of thermodynamic data in program databases are often a subject of controversy. Constants AS AH AZ ° from different sources for the same compound may turn out incompatible. This difference is especially prominent at comparison of the data from domestic and foreign sources. For instance, free enthalpy of KH PO formation after Kraynov et al. (2004) is -1,411.4 kJ-mole and after Lances Handbook of Chemistry (1999) -1,622.85 kj-mole" in case of H AsO " the same parameter has values -593,73 and -587,22 kj-mole in the same sources. Errors associated with this show up at the determination of pH, SI, etc. There is some level of consent between commonly available databases for most common minerals and water components. This does not mean, however, that the results are equally correct or precise. Sometimes it is caused by different notions of precision and correctness. The responsibihty for errors caused by database parameters is on the user, not on the program creator. For this reason critical evaluation of the utilized database by the user is a must. He has the right to edit his databases on his sole discretion regardless of the nature and intent of the program. In this connection he must be appraised of the current literature and current changes in necessary thermodynamic constants. 

Technical ceramics ate classed highly because of their high performance index. However, these materials are often used by sintering, and are liable to exhibit porosity, which is incompatible with the function of hermetic sealing. This criterion corresponds to a suitability for processing yet it carmot be expressed as a material property available in the databases, but it eliminates these materials. 

They produce redundancy and incompatibility. In addition to redundant and incompatible user interfaces, closed systems foster data redundancy, hardware and software incompatibility, duplication of programs and duplication of security schemes. In some cases, the user or programmer finds it easier to re-enter data that already reside in an existing database than to build a bridge to extract the information. Clearly, such duplication makes maintenance of consistency between data in various databases a major challenge. Each level of redundancy compounds the problem. Not only are direct costs increased unnecessarily, but the integrity, accuracy, and security of information are threatened. 

ERP systems provide more data integrity, use of accessible databases, and consolidation of many different incompatible systems. The ERP system focuses on capturing all of the transactions in a firm. But, the ERP system does not suggest which decisions to make about the supply chain. 

Materials, West Conshohocken, PA, www. astm.org). In plasticizers, the hydroxyl value includes -OH groups present in any free unesterified alcohol as well as those of the plasticizer molecule itself. In some plasticizers, large hydroxy values signal that the plasticizer may become incompatible on aging. In urethane technology, hydroxyl number is an important factor in the selection of polyols to achieve desired characteristics in elastomers and foams. Wypych G (ed) (2003) Plasticizer s database. Noyes Publication, New York. 

---