Homogeneous catalysts. With a homogeneous catalyst, the reaction proceeds entirely in the vapor or liquid phase. The catalyst may modify the reaction mechanism by participation in the reaction but is regenerated in a subsequent step. The catalyst is then free to promote further reaction. An example of such a homogeneous catalytic reaction is the production of acetic anhydride. In the first stage of the process, acetic acid is pyrolyzed to ketene in the gas phase at TOO C  [c.46]

If indirect heat transfer is used with a large temperature difference to promote high rates of cooling, then the cooling fluid (e.g., boiling water) is fixed by process requirements. In this case, the heat of reaction is not available at the temperature of the reactor effluent. Rather, the heat of reaction becomes available at the temperature of the quench fluid. Thus the feed stream to the reactor is a cold stream, the quench fluid is a hot stream, and the reactor effluent after the quench is also a hot stream.  [c.329]

C. It is secreted along with noradrenaline by the adrenal medulla, from which it may be obtained. It may be synthesized from catechol. It is used as the acid tartrate in the treatment of allergic reactions and circulatory collapse. It is included in some local anaesthetic injections in order to constrict blood vessels locally and slow the disappearance of anaesthetic from the site of injection. Ultimately it induces cellular activation of phosphorylase which promotes catabolism of glycogen to glucose.  [c.16]

Most enzymes work best within a narrow pH range and are susceptible to a wide variety of compounds which inhibit or sometimes promote the activity. The majority of enzymes work most efficiently at around 40°C and at higher temperatures are rapidly destroyed.  [c.159]

The swelling of gels is markedly affected by the presence of electrolytes, this effect being a minimum at the isoelectric point of the material. In general, sulphates, tartrates, etc. inhibit swelling, while iodides and thiocyanates promote the swelling. Thus gelatine disperses completely in iodide solution even at low temperatures.  [c.382]

The vitamin deficiency is often due to failure to absorb B12 from the stomach and can be alleviated by giving mg doses with extracts of hog s stomach which contains the intrinsic anti-pernicious anaemia factor (a muco-protein), which promotes the absorption.  [c.423]

To promote auto-ignition, especially under marginal operating conditions — cold starting, for example— a high compression ratio is necessary, generally between 15 and 22 according to the type of technology, e.g., direct or prechamber. This distinction along with other purely thermodynamic considerations such as average specific heat of the gases present in the cylinder, explain the generally high efficiency of the diesel engine.  [c.212]

The method for determining potential gums (NF M 07-013) consists of artificially promoting the oxidation to attempt to simulate conditions of prolonged storage. The gums are then recovered by filtration after a storage period of 16 hours at 100°C and under an oxygen pressure of 7 bar. The potential gums content has no official specification it is considered only as an indication. Moreover, its significance becomes very doubtful for fuels containing oxygenates such as alcohols and ethers.  [c.242]

Unlike spark-induced combustion engines requiring fuel that resists autoignition, diesel engines require motor fuels, for vhich the reference compound is cetane, that are capable of auto-igniting easily. Additives improving the cetane number will promote the oxidation of paraffins. The only compound used is ethyl-2-hexyl nitrate.  [c.350]

In the last decade new detectors which are based on imaging plates (IP) were introduced in various fields of radiographic X-ray and radionuclide imaging such as medical X-ray diagnostics, biomedical autoradiography and crystallography (1-2) Compared to other image detectors the IPs have several advantages as for example high sensitivity of 10 to 10 times that of radiographic films, high dynamic range in exposure dose (more than 6 orders of magnitude), excellent intrinsic spatial resolution, large area and negligible spatial distortion, reusability and digital output (1). The utilization of IPs is not limited only to imaging of X-rays, electrons and of heavier charged particles but can be extended also to imaging of neutrons. Therefore it is desirable to expand the use of IP also to neutron radiography and neutron imaging. During the last year we have conducted a research to exploit various application possibilities of IPs of different types in neutron radiography (NR) and neutron imaging and preliminary results were already reported elsewhere (3,4). The aim of this paper is to promote the use of the new imaging detector in the nuclear technology field and to introduce it to the professional community..  [c.505]

In world practice RCT application is considered to the decision of control of the high density objects. The particular feature of RCT is the possibility of the reception of the quantitative information. Besides, the absence of characteristic to X-ray CT result distortions, which are caused by variation of an average value of polychromatic radiation energy, when it passes through an article, promotes the increase of accuracy characteristics of radionuclide CT  [c.598]

In the first case, the ultrasonic signal is disturbed by a low frequency component due to thermal phenomenon which prevents from the visualization of elastic waves (Fig. 5.a). Nevertheless, this configuration is interesting because of its analogy with the emission-reception configuration of focused transducers. Thus, to reduce the thermal phenomenon, we introduce an analogical high-pass filter (Fig. 5.b). Some oscillations still appear at the beginning of the signal (ultrasonic signal ten times shorter than in figure 5.a), able to disturb the detection of a lack of weld penetration according to the sample thickness and the material propagation velocities. A solution to completely eliminate the thermal component is to separate the pump and the probe beams. In this case, the Rayleigh wave added to the bulk waves is also generated and detected. The arrival time of this surface wave depends on the distance separating the two laser beams and on the material velocities. By considering the specific directivity patterns of the ultrasonic waves, the shifting distance has also to be adjusted to promote either the longitudinal or the shear wave generation. The interaction between the generation laser beam and the cylindrical surface involves that the spatial distribution of the source is ehosen circular more than linear for a better ineident energy distribution. So, the directivity pattern of the shear wave and the energy reflection coefficients in the far field allow to determine the optimal incident angle to obtain a total reflection of the shear wave. For gold-nickel alloy, this angle is around 24° (vl=3575 m/s et v-r=1430 m/s), while for tantalum, it is around 29° (vl=4170 m/s et Vx=2050 m/s). Thus, the distance separating the generation and the detection is equal to 2.2 mm for both.  [c.696]

Promoting competitive and sustainable growth  [c.930]

Management and quality of water Global environmental change and climate Promoting the sustainable use of energy  [c.930]

Promoting competitive and sustainable growth 3,100  [c.931]

The "Plant Life Assessment Network (PLAN) mentioned first is a network promoted by the Commission to coordinate research funded under the EU Programmes in the area of Plant Life Assessment. This network therefore acts as a coordinating forum for both projects and the other networks mentioned, and will be described in further details below.  [c.933]

A natural concentration will be in the 3rd Thematic Programme on "Promoting Competitive and Sustainable Growth" and specially its Key Action 1 on Products, Processes and Organisation .  [c.934]

Technologies to minimize resource consumption, to promote waste recovery and to develop clean processes and products  [c.934]

Unfortunately, the main European companies which are working in the NDT field, do not show any activity in promoting in the Ukrainian market the high-technology NDT equipment for upgrading the NDT practices We welcome those who are starting to work in Ukraine, as our industry requires the advanced NDT technologies and equipment.  [c.971]

A great deal of effort has been put into promoting some seismic techniques for this same purpose. The obvious advantage being that they require only one-sided access and are more easily applied on site. However, seismic pulse echo techniques will only under the right circumstances give an indication of the risk of voids occurring inside ducts, and will not give a confident answer. The reason for this is that concrete has a tendency to shrink causing loss of bond from the cable duct wall. A lack of bond caused by shrinkage or other reasons will cause the seismic wave to reflect from the duct walls, in the same way as would a large void.  [c.1002]

As a result of the review exercise the recommendations given in the LR Rules regarding the minimum extent of NDE have been amended as shown in Figure 2. The intent of the changes is twofold, first, to merge NDE checkpoints taken for Classification purposes with those taken for Quality Control reasons, the second being to promote the wider use of ultrasonics for the examination of structurally important welds having configurations unsuitable for radiography.  [c.1042]

C. V. Boys, Soap Bubbles and the Forces that Mould Them, Society for Promoting Christian Knowledge, London, 1890 reprint ed.. Doubleday Anchor Books, Science Study Series S3, Doubleday, Garden City, NY, 1959.  [c.43]

The presence of the large repulsive potential barrier between the secondary minimum and contact prevents flocculation. One can thus see why increasing ionic strength of a solution promotes flocculation. The net potential per unit area between two planar surfaces is given approximately by the combination of Eqs. V-31 and VI-22  [c.241]

One way to promote adhesion between elastomers and solid surfaces is to chemically bond (graft) a layer of chains to the surface. When this is done, the attached chains can interpenetrate the elastomer and provide adhesion due to entanglements and other interactions. This is shown in theoretical studies of adhesion promoters by de Gennes and co-workers [103] and in experimental studies on siloxane polymers [104]. In both theory and experiment there is a maximum in adhesion with grafting density. This is due to the ability of a chain from a layer of moderate grafting density to interpenetrate the elastomeric network while at high-grafting-density interpenetration is reduced. Failure between adhesive tape and a solid surface shows flow instability patterns similar to those found in dewetting studies [105].  [c.455]

In addition to AP being large, it is also desirable in promoting capillary penetration that the rate of entry be large. For the case of horizontal capillaries or, in general, where gravity can be neglected, Washburn [45] gives the following equation for the rate of entry of a liquid into a capillary radius r  [c.470]

Fabrics may be made water-repellent by reversing the conditions previously discussed in the promotion of the wetting of fabrics. In other words, it is again a matter of capillary action, but now a large negative value of AP is desired. As illustrated in Fig. XIII-3a, if AP is negative (and hence if the contact angle is greater than 90°), the liquid will tend not to penetrate between the fibers, whereas if AP is positive, liquid will pass through easily. It should be noted  [c.470]

McGraw-Hill books are available at special quantity discounts to use as premiums and sales promotions, or for use in corporate training programs. For more information, please write to the Director of Special Sales, McGraw-Hill, Inc., 11 West 19th Street, New York, N.Y. 10011. Or contact your local bookstore.  [c.464]

N,N,N, N -tetramethyl-l,8,-naph-thalenediamiDe M.P. 51 C. A remarkably strong mono-acidic base (pKg 12-3) which is almost completely non-nucleophilic and valuable for promoting organic elimination reactions (e.g. of alkyl halides to alkenes) without substitution.  [c.60]

C2H3N. Colourless liquid with strong ammoniacal smell b.p. 56 C. Miscible with water and strongly basic. Prepared commercially from 2-aminoelhanol. Pure dry aziridine is comparatively stable but it polymerizes explosively in the presence of traces of water. Carbon dioxide is sufficiently acidic to promote polymerization.  [c.138]

TMED, (CH3)2NCH2CH2N(CH3)2. B.p. 122 C a hygroscopic base which forms a hydrocarbon-soluble stable chelate with lithium ions and promotes enhanced reactivity of compounds of lithium, e.g. LiAlH4, UC4H9, due to enhanced kinetic basicity of the chelate. Used in polymerization catalysts, tetramethyl lead, TML 5 lead tetramethyl.  [c.391]

Diesel fuels, like gasoline, are formulated with additives that affect the process of combustion, in this case to improve the cetane number. Diesel fuels also contain detergents for irijection systems as well as compounds for improving the fuel s low tempierature rheology. Finally, decreasing particulate emissions is a problem of increasing concern, but the mechanism of action to promote this effect is not clearly understood.  [c.350]

The comparative analysis of the experimental data is giving possibilities to observe a partial action of the Kayzer effect in the carbon plastic, and to bring out the accumulation effect /4/. The last is consisting in the following if the material was unloaded quick after it was loaded up to the task level, then the AE at the repeated loading is appearing at the loading level, which is different Ifom the initial. The part of the initial loading (AG), which is promoting AE at the repeated loading, is the accumulation coefficient.  [c.84]

The Government is making strenuous effort to develop local industries to create employment and reduce dependence on imports in many sectors for ultimate goal of achieving socio economic development of the people. Simultaneously, it is high time now to see that the use of the local NDT expertise is ensured so that the national economic development is supported by promoting quality productivity of industrial enterprises and their competitiveness. Accordingly much progress is to be achieved for the institutional infrastractural developments for application of NDT in Bangladesh in which international community of scientists, engineers researchers including similar institutions also too have great roles to play as her partner in progress.  [c.921]

Networking of researchers is generally promoted, Nationally as well as Europeanwide, and Brite-EuRam is contributing by supporting a number of networks, grouping research activities within certain themes. It is expected that the participating projects will benefit through the possibilities this will give to exchange high level information, and hopefully also in some cases join efforts in the development of common technological as well as commercial potentials - ultimately to the benefit of the European industry and citizens.  [c.932]

Classification Societies exist to promote the safe construction of ships and to protect that condition throughout the life of the vessel. One of the tools available to shipbuilders, shipowners and surveyors that can be used to achieve these aims is Non-Destructive Examination (NDE). The intent of this presentation is to describe the application of NDE to hull structure during construction and also during periodic surveys as seen from the viewpoint of the Classification Surveyor.  [c.1041]

An important problem involving reactions of solid surfaces is the deterioration of wall paintings and stone monuments. A significant source of damage to frescoes is the presence of water, which can degrade the binding media, alter pigments, and promote microbial growth and the collection of dirt and pollutants. While environmental factors such as relative humidity and surface temperature can be controlled by conservators, the presence of hygroscopic salts facilitate water absorption. Deliquescent salts, those that absorb water to produce a saturated solution at the surface of the painting, are especially problematic. Ferroni and co-workers have studied the cycles of deliquescence and recrystallization in calcium nitrate, Ca(N03)2 4H2O [176, 177]. Their understanding of the reactions at solid surfaces of paintings has helped define conditions to minimize their wetting by water vapor and subsequent deterioration. Stone sculptures and buildings decay through a process where the calcium carbonate reacts with sulfur oxides found in atmospheric pollutants to produce a more soluble salt. Gypsum (calcium sulfate dihydrate) produces black scabs on stone surfaces which not only ruin the appearance of the object but weaken the material and eventually flake off to expose a fresh surface to continue the cycle of decay (see Ref. [178]).  [c.284]

It is quite clear, first of all, that since emulsions present a large interfacial area, any reduction in interfacial tension must reduce the driving force toward coalescence and should promote stability. We have here, then, a simple thermodynamic basis for the role of emulsifying agents. Harkins [17] mentions, as an example, the case of the system paraffin oil-water. With pure liquids, the inter-facial tension was 41 dyn/cm, and this was reduced to 31 dyn/cm on making the aqueous phase 0.00 IM in oleic acid, under which conditions a reasonably stable emulsion could be formed. On neutralization by 0.001 M sodium hydroxide, the interfacial tension fell to 7.2 dyn/cm, and if also made O.OOIM in sodium chloride, it became less than 0.01 dyn/cm. With olive oil in place of the paraffin oil, the final interfacial tension was 0.002 dyn/cm. These last systems emulsified spontaneously—that is, on combining the oil and water phases, no agitation was needed for emulsification to occur.  [c.504]

See pages that mention the term Promoter : [c.69]    [c.33]    [c.47]    [c.81]    [c.177]    [c.189]    [c.294]    [c.310]    [c.338]    [c.370]    [c.216]    [c.1012]    [c.419]    [c.473]   
Industrial ventilation design guidebook (2001) -- [ c.1470 ]