Historical limitation

Acute and Chronic Toxicity. Although chromium displays nine oxidation states, the low oxidation state compounds, -II to I, all require Special conditions for existence and have very short lifetimes in a normal environment. This is also tme for most organ ochromium compounds, ie, compounds containing Cr—C bonds. Chromium compounds that exhibit stabiUty under the usual ambient conditions are limited to oxidation states II, III, IV, V, and VI. Only Cr(III) and Cr(VI) compounds are produced in large quantities and are accessible to most of the population. Therefore, the toxicology of chromium compounds has been historically limited to these two states, and virtually all of the available information is about compounds of Cr(III) and/or Cr(VI) (59,104). However, there is some indication that Cr(V) may play a role in chromium toxicity (59,105—107). Reference 104 provides an overview and summary of the environmental, biological, and medical effects of chromium and chromium compounds as of the late 1980s. 

Another factor that has historically limited the use of displacement chromatography, especially in the industrial setting, has been the lack of commercial availability of suitable displacers. Up until very recently, there was no dedicated commercial source for displacers. Sachem, Inc. has... 

There is no doubt that everyone is familiar with Moore s law, the doubling of data density per integrated circuit every 2 years. The performance of integrated circuit devices, historically limited by the characteristics of the transistors, is today limited by the electrical characteristics of the interconnect. The needed improvements in the interconnect performance are achieved with copper and a reduction in the insulator dielectric4 constant due to the associated reduction in the interconnect capacitance, the cross-talk, and the power consumption. 

This CPU issue along with historical limitations in analytical chemistry have often forced practice-oriented reaction models to be at a global level. These models traditionally involve the relevant boiling point or solubility defined reactants, and not the controlling molecules or intermediates. Thus they will often appear to suffer from the point of view of chemical significance however they are generally much easier to solve. Most importantly, these models are relevant the reactants and products in these models are bought and sold ... 

Iterative resolution methods are in general more versatile than noniterative methods. They can be applied to more diverse problems, e.g., data sets with partial or incomplete selectivity in the concentration or spectral domains, and to data sets with concentration profiles that evolve sequentially or nonsequentially. Prior knowledge about the data set (chemical or related to mathematical features) can be used in the optimization process, but it is not strictly necessary. The main complaint about iterative resolution methods has often been the longer calculation times required to obtain optimal results however, improved fast algorithms and more powerful PCs have overcome this historical limitation. 

All approaches to method optimization based on multiple experiments have the requirement that all components be detected and that they be tracked between runs. For complex samples, this is typically the most labor-intensive aspect of method development. For unattended method development, the instrument is required to monitor the change in retention of each component automatically. The historical limitations to this technology have been a key stumbling block in the widespread adoption of automated method development. 

Since ferritic stainless steels contain more carbon than other classes, they are relatively harder to weld and shape than other varieties, which have historically limited their applications. However, since the 1960s, processes such as argon oxygen decarburization have resulted in steels with less carbon, allowing for smaller concentrations of chromium to be used. As a result, the price for ferritic stainless steel has dramatically dropped, and a number of applications now employ these materials - more than 2/3 of which include automotive exhaust systems. 

Vermeulen, R., and Kromhout, H. (2005). Historical limitations of determinant based exposure groupings in the rubber manufacturing industry. Occup Environ Med 62, 793-799. 

Makalani, Minkah. 2001. A Biracial Identity or a New Race The Historical Limitations and Political Implications of a Biracial Identity for People with One Black and One White Parent. Souls A Critical Journal of Black Politics, Culture, and Society 3, no. 2 (Fall) 73-102. 

Despite the recent advancements in the field, EMR has been historically limited by the available injection solution materials, which have been constrained by two design... 

Currently, the majority of PW generated worldwide at onshore facilities is re-injected into the soil in disposal wells and therefore, the treatment facilities are mostly designed to remove dispersed oil and grease (O G) and suspended solids (SS) to avoid formation plugging. The main treatment objective is to reduce O G to acceptable levels and mitigate toxicity impacts on aquatic fauna and flora. As a consequence, the PW treatment methods applied in the petroleum industry are historically limited to physical separation technologies such as API separators, coalescers or hydro-cyclones. These technologies are. 

The uptake of HRMS instrumentation into metabolite identification laboratories points to future developments and uses for these types of mass analyzers. From a hardware perspective, developments in TOF and Orbitrap technology will be needed to address lingering issues specific to these analyzers. In the TOF area, current commercial systems just coming to the market have addressed historical limitations of resolution, dynamic range, and mass accuracy. It remains to be seen if these specifications are sufficient or if further gains are needed. These instruments are not yet as sensitive as high-end triple quadrupole mass spectrometers, and improvements are needed in this area. For Orbitrap-based systems, the main limitations are scan speed and sensitivity. As... 

As a class, urethane adhesives have somewhat poorer thermooxidative and moisture resistance than acrylic and epoxy structural adhesives. This has historically limited their expansion into certain areas of use. A 2K adhesive having the ability to survive automotive paint oven temperatures, which rim as high as 205° C,... 

Classification of fuel cells by temperature is becoming more blurred, however, since a current SOFC research focus is lower temperature (<600°C) operation to improve start-up time, cost and durability, while a focus of PEFC research has been to increase operation temperature to > 120°C to improve waste heat rejection and water management. The ideal temperature seems to be around 150-200°C which is where the PAFC typically operates. However, the PAFC has its own historical limitations which have hampered enthusiasm for its continued development. 

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