Comparative study

In a search for new catalysts, it is often necessary to compare the activity of different materials. For such a comparative study of different catalysts in the same experimental setup, it is necessary to obey certain rules. 

The experimental conditions should be chosen such that the thermodynamic equilibrium is not approached. 

Proper flow-patterns should be ensured and the formation of strong concentration gradients should be avoided. 

The contribution of the uncatalyzed reaction should be known and the application of inert reactors is advisable, although not always possible. 

To avoid by-pass gas flow the reactor diameter should be at least 10 times larger than the particle diameter. 

At the conclusion of the work, the project was regarded as having achieved its primary target of formulating new systems to improve the scorch performance that could be obtained by a commercial DeLink system by using combinations of chemicals that were less active at the revulcanisation stage. However, the workers found that no single system could be used for all applications as each had its limitations. There were two principal conclusions  

The project s goals, to achieve both an improvement in scorch performance and good physical properties, were not fully achieved, but WRAP felt that there was potential for them to be achieved in the future, for example by using a combination of a high level of a less hindered sulfenamide, such as CBS, with a small amount of a less active zinc-based accelerator, such as zinc ethylphenyl dithiocarbamate. 

The paper presented by Kind at RubberChem 2010 [26] described the processes that the UK company Polymer Recyclers Ltd (PRL) had developed to convert powdered end-of-life rubbers into high-quality rubber ingredients that are in the form of MB-containing 

DIN Deutsches Institut fiir Normung e.V. ODR Oscillating disc rheometer  

Kind was able to conclude from these data that only milling crumb without the addition of chemicals was ineffective and that the Levgum and ReTurn processes gave good tensile, tear and abrasion loss results, with similar values. It was stressed that it was difficult to translate the obtained results into results that would be obtained commercially as the milling process was carried out on a relatively small scale. 

One of the most significant uses of thermal equipment is in the comparison of samples, for example when comparing the effect of additives and fillers on a material, for troubleshooting when comparing good and bad samples, or when comparing a competitor s materials with 

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Hermann R and Muiier M 1991 High resoiution bioiogicai scanning eiectron microscopy a comparative study of iow temperature metai coating techniques J. Eiectron. Microsc. Tech. 18 440-9... 

Akkermans R P, Wu M, Bain C D, Fidel-Suerez M and Compton R G 1998 Electroanalysis of ascorbic acid a comparative study of laser ablation voltammetry and sonovoltammetry E/eofroana/ys/s 10 613... 

Gray C G, Sainger Y S, Joslin C G, Cummings P T and Goldman S 1986 Computer simulation of dipolar fluids. Dependence of the dielectric constant on system size a comparative study of Ewald sum and reaction field approaches J. Chem. Phys. 85 1502-4... 

Kang S Y and Kim K 1998 Comparative study of dodeoanethiol derivatized nanopartioles prepared in one and two phase systems Langmuir 14 226... 

Stella A ef al 1996 Comparative study of thermodynamic properties of metallic and semiconducting nanoparticles in a dielectric matrix Mater. Res. Soc. Symp. Proc. 400 161... 

Kurst G R, R A Stephens and R W Phippen 1990. Computer Simulation Studies of Anisotropic iystems XIX. Mesophases Formed by the Gay-Berne Model Mesogen. Liquid Crystals 8 451-464. e F J, F Has and M Orozco 1990. Comparative Study of the Molecular Electrostatic Potential Ibtained from Different Wavefunctions - Reliability of the Semi-Empirical MNDO Wavefunction. oumal of Computational Chemistry 11 416-430. 

Comparative studies have been undertaken between different heterocyclic series, especially the azoles, thiazoles. oxazoles. imidazoles, and selenazoles. In a large number of these studies, the heterocycles are condensed w ith aromatic nuclei. 

The text form for parameters uses white space or commas to separate the fields (columns) of the parameter files. They can be read by ordinary text editors, word processors, etc. In the text form, parameters are easy to modify but not easy to compare, study, etc. Many database programs are capable of reading columns of text as a database, however. While spreadsheets are not, per se, databases, they can be useful for examining parameter sets. Microsoft Excel, for example, can read the text form of a parameter file and put the data in a form easily manipulated as a matrix or a database. The text form of parameters are stored, by default only, in. txt files. 

The computation of mesopore size distribution is valid only if the isotherm is of Type IV. In view of the uncertainties inherent in the application of the Kelvin equation and the complexity of most pore systems, little is to be gained by recourse to an elaborate method of computation, and for most practical purposes the Roberts method (or an analogous procedure) is adequate—particularly in comparative studies. The decision as to which branch of the hysteresis loop to use in the calculation remains largely arbitrary. If the desorption branch is adopted (as appears to be favoured by most workers), it needs to be recognized that neither a Type B nor a Type E hysteresis loop is likely to yield a reliable estimate of pore size distribution, even for comparative purposes. 

H. O. Hardenburg, "Comparative Study of Heavy-Duty Engine Operation with Diesel Puel and Ignition-Improved Methanol," Sy4E Paper 872095, SyPE Int. Fuels and Eubricants Meeting andExpo. (Toronto, Canada, Nov. 2—5,1987), Society of Automotive Engineers, Warrendale, Pa. 

M. R. Olsen and R. K. Major, Comparative Study of Dehydrating Processes in the Manufacture of Nitrocellulose, United Technology Chemical Systems Division, Suimyvale, Calif., 1975. 

B. D. Pomeroy and co-workers. Comparative Study andEvaluation of Advanced Cycle Systems, Electric Power Research Institute, Palo Alto, Calif., Report AE-664,1, Eeh. 1978. 

A multiple chent study may serve many useful purposes to company management. It may act as a primer for intensive study of a narrower part of the market, a guide to deciding whether to expend R D effort in the field, or a guide to deciding whether to acquire a company already in the field. The independent study can also resolve conflicting opinions within different departments of the chent company. Finally, the cost of a multiple chent study is usually lower than the cost of a comparable study by a chents in-house personnel. 

Databases differ in their strengths and weaknesses, as well as in their focus. As a result, dupHcate searches carried out on different databases generally produce different results. This has been demonstrated in comparative studies of retrieval results for a group of patent databases (31,32). Participants in one study (31) made an effort to develop optimal search strategies in each database tested, yet in no instance did one file produce perfect retrieval. Both investigations (31,32) found that results from the various databases complemented each other. As a result, searchers are counseled to use multiple databases whenever possible. There is no pat answer to the question of how many files to use or which files to use however, more files mean more expenditure, and searchers must develop their own cost—benefit relationship. 

Pesticides A. Comparative Study of Industrialized Nations Regulatory Systems, GAO/PEMD-93-17, U.S. General Accounting Office, Washington, D.C., July 1993,104 pp. 

Comparative studies were performed to evaluate microwave digestion with conventional sample destmction procedures. These included the analysis of shellfish, meats, rocks, and sods. Generally, comparable accuracy at much shorter digestion time was found for the MAE vs the classical digestion method (39). 

Anistreplase has a considerably longer a half-life than streptokinase, ie, 90 min compared to 20 min (87,88). Moreover, it does not require prolonged infusion to achieve its thrombolytic effects. Anistreplase was found to be highly effective after a single intravenous dose of 30 units over a 5-min period compared to a 60-min infusion of 1.5 million units of streptokinase (89—94). In direct comparative studies, anistreplase was as effective as intracoronary (95,96) and intravenously (96—100) adrninistered streptokinase. In a randomized, double-blind, placebo-controUed study (AIMS trial) with 1004 patients given this modified enzyme, the 30-day mortaUty rate was 12.2% for patients receiving placebo, compared to 6.4% for patients who received 30 units of anistreplase intravenously within six hours of the onset of symptoms (101). 

Compared to streptokinase, urokinase has been less extensively studied because of its high cost, ie, about 10 times that of a comparable treatment with streptokinase. In addition to the indications described for streptokinase, urokinase is indicated for use in patients with prior streptokinase treatment, or prior Streptococcal infection. Urokinase is commonly used at a loading dose of 4400 units /kg, with a maintenance intravenous infusion dose of 4400 units/kg/h for thromboses other than acute myocardial infarction. In the latter case, a much larger dose, ie, 0.5—2.0 million units/h or a bolus dose of 1.0 million units followed by a 60-min infusion with 1.0 million units, has been found optimal (106). An intracoronary dose of 2000 units/min for two hours was used in one comparative study with intracoronary streptokinase (107). In this study, urokinase exhibited efficacy equivalent to streptokinase with fewer side effects. Other studies with intracoronary urokinase have adrninistered doses ranging from 2,000 to 24,000 units/min with a reperfusion efficacy of 60—89% (108—112). In another urokinase trial, 2.0 million units were adrninistered intravenously, resulting in a thrombolytic efficacy of 60% (113). Effectiveness in terms of reduction in mortaUty rate has not been deterrnined because of the small number of patients studied. 

A theoretical, comparative study of the tautomerism of 56 five-membered heterocyclic rings announced in (76AHC(Sl)l) has appeared (81MI40402). The stabilities of the three forms for 5-pyrazolones, 5-pyrazolethiones and 5-aminopyrazoles have been calculated by a simple Hiickel o) iterative method. The relative energies and the substituent and solvent effects are in agreement with the experimental results. 

Comparison Data—Plate Dryers Comparative studies have been done on products under both atmospheric and vacuum drying conditions. See Fig. 12-79. These curves demonstrate (1) the improvement in drying achieved with elevated temperature and (2) the impact to the drying process obtained with vacuum operation. Note that cui ve 4 at 90°C, pressure at 6.7 kPa absolute, is comparable to the atmospheric cui ve at 150°C. Also, the comparative atmospheric cui ve at 90°C requires 90 percent more diying time than the vacuum condition. The dramatic improvement with the use of vacuum is important to note for heat-sensitive materials. 

The aim of this work is to analyse processes for determination and removal (or reducing) greenhouse gases (GHG NO, SO, and CO) from air and make the comparative study of GHG emission and with production of electricity. Among various analytical methods green analytical techniques were analysed and tested for GHC determination. 

We have conducted the comparative study of gold (III), platinum (IV) and palladium (II) acidocomplexes solution on macroporous granular sorbents on the basis of polystyrene with functional groups of methyleneamine, 3-methylpyrasolyl, N,N-dimethylaminomethylene, dimethylmethylene-P-oxyethylamine and with functional 6-(3-methylpyridine) groups on polyvinylpyridine basis as well as fibrous polystyrene sorbent with pyrazolyl groups. 

COMPARATIVE STUDY OF SPE AND LEE FOR PRECONCENTRATION OF URINARY 1-HYDROXYPYRENE AS A BIOMARKER OF EXPOSURE TO PAHS PRIOR TO HPLC... 

Table 6.5 Comparative study of performance of an a.c. drive, variable speed fluid coupling and a d.c. drive...

Industrial Power Engineering and Applications Handbook Table A16.2 Comparative study of different insulating systems... 

Figure 24.21 A comparative study of load transfers for different line lengths at different p.fs. for an uncompensated line...

Shahpar S., A Comparative Study of Optimization Methods for Aerodynamic Design of Turbomachinery Blades, 2000-GT-523. 

Whitney, W.J., Comparative Study of Mixed and Isolated Flow Methods for Cooled Turbine Performance Analysis, NASA, TM X-1572, 1968. 

Koestel, A., P. Hermann, and G. I... Tuve. 1950. ASHVE Research Report No. 1404 Comparative study of ventilating jets from various types of outlets. ASHVE Transactions, vol.. 56, p. 459. 

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