Element secondary

The majority of heat-resisting alloys contain at least one element which is selectively oxidised (e.g. Cr, Si, Al). The resulting scale is highly protective, but depletion of the secondary element may occur if the diffusion rate of this element in the alloy is low. Then repetitious loss of the scale can be profoundly detrimental to long-term performance, since depletion of the alloying element near the surface may occur to such an extent that its concentration falls below the critical level for the exclusive reformation of the highly protective scale... 

The mass separated, pulsed, and focused primary ions with the energy of 1 -25 keV, typically liquid metal ions such as Ga, Cs, and O", are used to bombard the sample surface, causing the secondary elemental or cluster ions to emit from the surface. The secondary ions are then electrostatically accelerated into a field-free drift region with a nominal kinetic energy of ... 

The flow of fluids is most commonly measured using head flowmeters. The operation of these flowmeters is based on the Bernoulli equation. A constriction in the flow path is used to increase the flow velocity. This is accompanied by a decrease in pressure head and since the resultant pressure drop is a function of the flow rate of fluid, the latter can be evaluated. The flowmeters for closed conduits can be used for both gases and liquids. The flowmeters for open conduits can only be used for liquids. Head flowmeters include orifice and venturi meters, flow nozzles, Pitot tubes and weirs. They consist of a primary element which causes the pressure or head loss and a secondary element which measures it. The primary element does not contain any moving parts. The most common secondary elements for closed conduit flowmeters are U-tube manometers and differential pressure transducers. 

The analysis of the cytochrome crystal structures reveals extensive differences among the mammalian and the human CYPs that may reflect the structural flexibility of these enzymes and therefore the broad substrate specificity observed. In general, the secondary elements and the overall structure of the CYP are conserved. Nevertheless, it seems that in most enzymes, the most flexible regions are located between the F-G helixes and the B-C loop. For example in the CYP2B4 apoprotein (lpo5) the... 

Recently, several CYP crystal structures have been deposited in the P D B and could be used to understand the different metabolic properties. From the analysis of the different protein structures, it could be concluded that in general CYPs maintain the secondary elements across the different subfamilies, but they have a quite high flexibility, accommodating the protein structures to the ligand bound in the enzyme cavity. 

Given these Lego concepts, some aspects of comparative sequence analysis are reviewed next. First it is clear that there can be at least two levels of background sequence similarity that do not reflect common ancestry. The first is the local similarity between similar types of secondary elements, and second is that between sequences of secondary elements in similar folds. Thus one should anticipate that all four-helix bundles would have greater sequence similarity than that between an all-ce and an all-/3 protein, as well as greater than that between truly random sequences. This will complicate our ability to distinguish true homology from structural similarity (Henikoff and Henikoff, 1991 Claverie, 1995),... 

In Chapter 2, the electrochemical oxidation of carbon monoxide, which is considered as the key intermediate for methanol oxidation, is investigated using electrochemical and spectroscopic methods for polycrystalline and single crystal platiniim electrodes. In Chapter 3, the electrochemical oxidation of methanol on the same electrodes was treated. In Chapter 4, electrocatalytic activities of platinum modified by adding secondary elements will be disciissed. 

Effects and Roles of Secondary Elements on Platinum 4.1 Introduction... 

Table 4-1 Summaiy of effects of secondary elements deposited on Pt electrode on COad and methanol oxdatior... 

The most important feature of the reference spectrum data base is the provision to generate and store inverted data (data that are presorted on various secondary elements of the record). The data present in the spectrum data base may be inverted upon any specified characteristic, such as m/z value, and then be retrieved using that characteristic. For instance, a data file inverted about the daughter m/z value will contain, for each m/z value, a list of pointers to the reference daughter spectra that have a peak at that... 

Proteins often fold into a compact, globular form, composed of secondary elements such as beta sheets and alpha helices. This regular collection... 

Out of all the coins analyzed-833 total from both the Isfiya and the Qumran hoards-only 782 were able to be accurately dated. For both the Isfiya hoard and the Qumran hoard, of the 26 elements searched for, twelve were found in the coins (Ag, Cu, Au, Pb, Ni, Sn, Ti, Ni, Bi, Pt, Zn and Cr). Results of the analysis show that all the coins are considered to be veiy pure silver (excluding coin tyre 8823 with 78.69% Ag). A total of 701 of 705 coins in the Isfiya hoard have silver content over 92%, and 704 of the 705 coins have over 90% Ag. Twelve of the 128 coins analyzed in the Qumran hoard have silver values below 92% (88.04-91.75%). The major secondary elements present in the coins are Cu, Pb, and Au. Other trace elements range in value from 0% to 1.452%, but typically are very low with means below 0.45%. The more informative and interesting aspect to consider is the major elements, Ag, Cu, Au, and Pb and their relationship to one another (see Table III for mean values). 

There are two elements in a head flow meter the primary element is the restriction in the line, and the secondary element is the differential pressure measuring device. Figure 1 shows the basic operating characteristics of a head flow meter. 

The primary elements provide the input to the secondary element which provides for indications, alarms, and controls. 

A loss of differential pressure integrity of the secondary element, the DP transmitter, will introduce an error into the indicated flow. This loss of integrity implies an impaired or degraded pressure boundary between the high-pressure and low-pressure sides of the transmitter. A loss of differential pressure boundary is caused by anything that results in the high- and low-pressure sides of the DP transmitter being allowed to equalize pressure. 

Enamelling consists of forming an adherent glass on the metal surface. Surfaces treated in this way are resistant to attack from acids and weak alkalis. The glasses may be coloured and formed into decorative patterns for household ware and jewellery and are prodcued from a mixture of oxides of silicon, boron, sodium, calcium, and lead. Secondary elements are also added, e.g. nitrates and manganese dioxide, which oxidise impurities, other oxides to aid adhesion to the metal surface, and pigments to impart colour and opacity. 

Another approach is to map the arrangement of secondary structural elements onto the known tertiary structures of other proteins. Currently, approximately one hundred unique protein folds have been identified. There is some question as to if this is an upper limit. If this is indeed the case, then the protein of unknown structure must adopt a known topological fold. The secondary structural elements are mapped onto the template of the different known protein structures. The best fits, as judged by the environmental factors (solvent accessibility) of the individual amino acids, are then further analyzed as probable folds. This procedure is referred to as threading the secondary elements into three-dimensional structures [28],... 

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