Beryllium ratios

Subsequent studies showed that other species are formed to a small extent just before precipitation begins these species have a hydroxide to beryllium ratio greater than 1, but because their concentrations are always relatively low their identification has been dogged by controversy. Mesmer and Baes obtained data at a range of temperatures and from this data proposed the minor species Be5(OH)7+ (66). Later they also suggested that the species Be6(OH)3+ was formed (10), in agreement with earlier work by Lanza and Carpeni (69, 72). These last had also proposed the additional species Be3(OH)4+ and Be6(OH)ir. 

The small lithium Li" and beryllium Be ions have high charge-radius ratios and consequently exert particularly strong attractions on other ions and on polar molecules. These attractions result in both high lattice and hydration energies and it is these high energies which account for many of the abnormal properties of the ionic compounds of lithium and beryllium. 

The Elements Beryllium (Be), Magnesium (Mg), and Calcium (Ca) all formed oxides in fhe ratio of one afom per oxygen atom RO Boron (B) and Aluminum (Al) formed R2O3 Carbon (C) and Silicon (Si) formed RO2... 

Chemical Designations - Synonyms Beryllium Sulfate Tetrahydrate Chemical Formula BeS04 4H20. Observable Characteristics - Physical State (as normally shipped) Solid Color White Odor None. Physical and Chemical Properties - Physical State at 15 G and 1 atm. Solid Molecular Weight 177.14 Boiling Point at I atm. Not pertinent (decomposes) Freezing Point Not pertinent Critical Temperature Not pertinent Critical Pressure Not pertinent Specific Gravity 1.71 at 11°C (solid) Vapor (Gas) Density Not pertinent Ratio of Specific Heats of Vapor (Gas) Not pertinent Latera Heat of Vaporization Not pertinent Heat of Combustion Not pertinent Heat of Decomposition Not pertinent. 

For the neutron porosity measurement, fast neutrons are emitted from a 7.5-curie (Ci) americium-beryllium (Am-Be) source. The quantities of hydrogen in the formation, in the form of water or oil-filled porosity as well as crystallization water in the rock if any, primarily control the rate at which the neutrons slow down to epithermal and thermal energies. Neutrons are detected in near- and far-spacing detectors, located laterally above the source. Ratio processing is used for borehole compensation. 

Beryllium is a light metal (s.g. 1 -85) with a hexagonal close-packed structure (axial ratio 1 568). The most notable of its mechanical properties is its low ductility at room temperature. Deformation at room temperature is restricted to slip on the basal plane, which takes place only to a very limited extent. Consequently, at room temperature beryllium is by normal standards a brittle metal, exhibiting only about 2 to 4% tensile elongation. Mechanical deformation increases this by the development of preferred orientation, but only in the direction of working and at the expense of ductility in other directions. Ductility also increases very markedly at temperatures above about 300°C with alternative slip on the 1010 prismatic planes. In consequence, all mechanical working of beryllium is carried out at elevated temperatures. It has not yet been resolved whether the brittleness of beryllium is fundamental or results from small amounts of impurities. Beryllium is a very poor solvent for other metals and, to date, it has not been possible to overcome the brittleness problem by alloying. 

In Table XVIII are given values of the radius ratio for the salts of beryllium, magnesium and calcium (those of barium and strontium, with the sodium chloride structure, also obviously satisfy the radius ratio criterion). It is seen that all of the sodium chloride type crystals containing eight-shell cations have radius ratios greater than the limit 0.33, and the beryl-... 

It is also shown that theoretically a binary compound should have the sphalerite or wurzite structure instead of the sodium chloride structure if the radius ratio is less than 0.33. The oxide, sulfide, selenide and telluride of beryllium conform to this requirement, and are to be considered as ionic crystals. It is found, however, that such tetrahedral crystals are particularly apt to show deformation, and it is suggested that this is a tendency of the anion to share an electron pair with each cation. 

WDSs have excellent resolving power, and the peak-to-background ratio of each line is much higher than can be achieved with a crystal detector. With a suitable crystal of large lattice spacing it is possible to detect and count X-rays as soft as boron K or even beryllium K , and this type of spectrometer is widely used when... 

Compounds of beryllium and aluminum are substantially covalent as a result of the high charge -to-size ratio, which causes polarization of anions and very high heats of hydration of the ions ( —2487kJ mol-1 for Be2+ and — 4690kJ mol-1 for Al3+). 

As is the case with numerous other metal alkyls, beryllium alkyls are spontaneously flammable in air. Beryllium oxide is produced, and it has a heat of formation of — 611kJ/mol. Dimethylberyllium also reacts explosively with water, and some of its other properties resemble those of trimethylaluminum. This should not be surprising because the metals have a strong diagonal relationship that relates to their similar charge-to-size ratios. 

The mass attenuation coefficient values of the elements are available in the literature [46]. Therefore, the mass attenuation coefficient of a compound can be calculated. Thus and (in Eq. 15) can be calculated provided the molecular formulas of components 1 and 2 are known. It is then possible to calculate the intensity ratio, /u/(/ii)o> as a function of xx. This ratio can also be experimentally obtained. The intensity of peak i of a sample consisting of only 1 is determined [(/ii )o] This is followed by the determination of the intensity of the same peak in mixtures containing different weight fractions of 1 and 2. This enables the experimental intensity ratio, /n/(/n)o, to be obtained as a function of xx. The principles discussed above formed the basis for the successful analyses of quartz-beryllium oxide and quartz-potassium chloride binary mixtures [45]. 

The above models are all rather unsatisfactory, because they involve somewhat arbitrary assumptions about the time-dependence of the cosmic-ray flux and spectrum and because they predict a secondary-like behaviour for Be and B abundances, whereas the overall trend indicated by the data is more like a primary one and there are the energetic difficulties pointed out above. In the case of nB, there is a possible primary mechanism for stellar production in supemovae by neutrino spallation processes (Woosley et al. 1990 Woosley Weaver 1995), but the primary-like behaviour of beryllium in metal-poor stars, combined with a constant B/Be ratio of about 20 fully consistent with cosmic-ray spallation (Garcia Lopez et al. 1998) in the absence of any known similar process for Be, indicates that this does not solve the problem unless a primary process can be found for Be as well. Indeed,... 

Beryllium was first demonstrated to be present in low-metallicity stars by Gilmore, Edvardsson and Nissen (1991) and soon confirmed by others, e.g. Ryan ei al. (1992) who gave the argument for a flattening in the Be/Fe ratio at [Fe/H]... 

Fig. 8.3. Lithium, beryllium and iron. The symbol [Fe/H] denotes the logarithm of the ratio of Fe/H for the star and Fe/H for the Sun. The evolution of lithium and beryUium in the halo [Fe/H] < — 1 is a classic example. The lithium content remains independent of the iron content in halo stars. This is known as the Spite plateau, named after the two French astronomers Monica and Fran ois Spite. It indicates a primordial origin (i.e. in the Big Bang). An upturn occurs just when the disk stars begin to take over. Berylhumis an archetypal example of elements created by spallation. Its abundance increases monotonicaUy by accumulation as time goes by.

A large increase in the O/Fe ratio in stars at low metallicity was reported by Israelian et al. in 1998 and by Boesgaard et al. in 1999, contradicting earlier data which suggested an approximately constant O/Fe ratio. Now oxygen is particularly relevant to the astrophysics of cosmic rays. This is because spallation products under collision include the light nuclei lithium, beryllium and boron. 

The Op mechanism leads to proportionality between oxygen and beryllium abundances, for example, because these two elements arise from the same source, namely, type 11 supernovas, oxygen directly and beryllium indirectly (via collisional disintegration of oxygen into beryllium). A constant Be/0 ratio, independent of O/H, would be the hallmark of the Op mechanism. 

An immunologic basis for chronic beryllium disease has been postulated and a hypersensitivity phenomenon demonstrated. Consistent with the concept of chronic berylliosis as a hypersensitivity pulmonary reaction are the following Persons with berylliosis also show delayed cutaneous hypersensitivity reactions to beryllium compounds their peripheral blood lymphocytes undergo blast transformation and release of macrophage inhibition factor after exposure to beryllium in vitro helper/suppressor T-cell ratios are depressed and there is lack of a dose-response relationship in chronic beryllium cases. Hypersensitization may lead to berylliosis in people with relatively low exposures, whereas nonsensitized individuals with higher exposures may have no effects. 

Another short-lived isotope of beryllium, 7Be, decays to 7Li by electron capture with a half-life of —53 days. This half-life is so short that any atoms present in chondrite components must have been produced in the solar system essentially immediately before the host object formed. A hint of the presence of 7Be in the form of large excesses of 7Li in an Allende CAI was presented by Chaussidon et al. (2006). However, these authors were not able to demonstrate a tight correlation with the 9Bc/ Li ratio. 

A corresponding reaction of acetate ion with AJP is also catalyzed by a bivalent metal ion. The reaction probably results in the formation of an acyl phosphate, which has not been identified as such but has been identified by trapping of the product with hydroxylamine. The best catalyst is beryllium ion, which catalyzes optimally at molar ratios of 1 to 1 or less. Acetate ion is presumably the reactive species, since the pH optimum of the reaction is 5. It is concluded from the pH effects in this study and in the transphosphorylation reaction that a complex of the metal ion and nucleophile must occur. Since acetate ion is a monodentate ligand, the mechanism postulated for the phosphorylation reaction above cannot be completely applicable to this case (36). 

Chemical Composition. Diamond is nominally pure carbon with a 12C 13C ratio of about 99 1. Although other elements are often reported in analyses, most are considered to be present in oxide, silicate, and sulfide phases as inclusions in the diamond. Only boron, nitrogen, and possibly beryllium are considered to be truly substitutional in the lattice. Hydrogen and oxygen, possibly as OH, may also be important structural contaminants though they may also be present as second-phase gases along with CO, C02, H20, CH4, and other species (20). 

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