SKELETAL SILVER CATALYSTS FOR THE OXIDATION OF ETHYLENE TO ETHYLENE OXIDE

1956 ◽  
Vol 34 (5) ◽  
pp. 665-671 ◽  
Author(s):  
A. Cambron ◽  
W. A. Alexander
Keyword(s):  
Ethylene Oxide ◽  
Alkaline Earth ◽  
Specific Activity ◽  
High Specific Activity ◽  
Alkaline Earth Metals ◽  
The Other ◽  
Silver Alloys ◽  
Silver Catalysts

Skeletal silver catalysts of high specific activity have been prepared by the removal of calcium from calcium–silver alloys. The activity of these catalysts in the oxidation of ethylene to ethylene oxide has been investigated. Catalysts prepared by the removal of the other alkaline earth metals from their alloys with silver have also been studied. It has been found that catalysts prepared from calcium–silver alloys show a higher specific activity and are more stable and more conveniently prepared than the catalysts from the other silver alloys investigated.

Analysis of the environment of beryllium, magnesium and alkaline earth atoms in oxygen-containing compounds

1999 ◽  
Vol 55 (2) ◽  
pp. 139-146 ◽  
Author(s):  
V. A. Blatov ◽  
L. V. Pogildyakova ◽  
V. N. Serezhkin
Keyword(s):  
Crystal Structure ◽  
Alkaline Earth ◽  
Organometallic Compounds ◽  
Alkaline Earth Metals ◽  
The Other ◽  
Crystal Chemical ◽  
Coordination Polyhedra ◽  
Coordination Numbers ◽  
Coordination Spheres

About 2100 inorganic and organometallic compounds containing beryllium, magnesium and alkaline earth atoms (M) were investigated with Voronoi–Dirichlet polyhedra (VDPs). It is shown that the coordination numbers (CNs) of the M atoms in MO n coordination polyhedra can be determined by means of VDPs without crystal-chemical radii. The distributions of the M—O distances in the coordination spheres of the M atoms are bimodal for M = Be or Mg and monomodal for the other alkaline earth metals. Beryllium and magnesium coordination polyhedra containing weak M—O contacts were classified by variants of their distortions. It is found that the volume of the domains of the Mg, Ca, Sr and Ba atoms is independent of their CNs at CN \ge 6 (up to 16 for barium). The possibility of using the model of deformable spheres to describe the crystal structure of the compounds investigated is suggested.

scholarly journals Luminescent detection method for immunodot, Western, and Southern blots.

1986 ◽  
Vol 34 (12) ◽  
pp. 1645-1650 ◽  
Author(s):  
M M Leong ◽  
C Milstein ◽  
R Pannell
Keyword(s):  
Monoclonal Antibody ◽  
Cell Line ◽  
Indirect Method ◽  
Detection Method ◽  
Specific Activity ◽  
High Specific Activity ◽  
The Other ◽  
X Ray ◽  
Bispecific Monoclonal Antibody ◽  
Direct Binding

An anti-peroxidase-anti-biotin hybrid hybridoma rat cell line, capable of producing a bispecific monoclonal antibody, has been derived to explore its use in conjunction with a luminol immunodetection system. Luminescence was detected using x-ray film. The method was sufficiently sensitive and effective, but was less sensitive than autoradiographic methods using high-specific-activity 32P-labeled probes. Exposure times, on the other hand, were of the order of seconds rather than days. The direct binding of both peroxidase and biotin by the bispecific monoclonal antibody is simpler but less sensitive than the more conventional indirect method using a commercial peroxidase coupled with anti-rat antibody as a developing antibody.

Comparative accumulation of Alkaline-earth metals by two freshwater Mussel species from the Nepean River, Australia: Consistences and a resolved Paradox

1993 ◽  
Vol 44 (4) ◽  
pp. 609 ◽  
Author(s):  
RA Jeffree ◽  
SJ Markich ◽  
PL Brown
Keyword(s):  
Alkaline Earth ◽  
Tissue Concentration ◽  
Freshwater Mussel ◽  
Dry Weight ◽  
Alkaline Earth Metals ◽  
The Other ◽  
Tissue Concentrations ◽  
South Wales ◽  
Solubility Constant ◽  
The Mean

Whole tissue concentrations of Be, Mg, Ca, Sr, Ba and 226Ra were determined in Hyridella depressa (Lamarck) and Velesunio ambiguus (Philippi) from a minimally polluted region in the Upper Nepean River, New South Wales. Although the mean tissue concentrations of each metal were comparable between the two species, their patterns of accumulation were dissimilar. For each metal, tissue concentration was significantly correlated (P≤0.01) with tissue dry weight and shell length in H. depressa, but not in V. ambiguus, in which variability between individuals was high and Mg concentration was inversely correlated (P≤0.05) with tissue dry weight. However, in each species the Ca concentration was a highly significant (P≤0.001) positive predictor of the concentration of each of the other metals. For each species, normalized rates of accumulation of the metals, relative to increasing Ca concentration and/or size, were 226Ra >Ba≥Sr>Ca > Mg; these rates were inversely related (P≤0.05) to their solubilities as hydrogen phosphates. This inverse relationship was used to predict a solubility constant for BeHPO4. The results were consistent with those previously obtained for V. angasi (Sowerby). The metal solubility relationships, based on the relative increases in the tissue concentrations of each metal over the range of Ca concentrations, held for both species even though V. ambiguus showed no significant (P>0.05) increase in tissue concentrations with size. This paradox can be explained as follows. In both species the Ca tissue concentration is a measure of the total influx and efflux of Ca and its analogues through the tissue of an individual over its lifetime; however, in V. ambiguus this total flux is unrelated to mussel size. The use of Ca concentration to predict concentrations of the other metals was effective in explaining up to 98% and 95% of the variability between individual mussels of H. depressa and V. ambiguus respectively. Hence, the problem of inherent variability between individuals can be eliminated. This will permit any spatial and/or temporal differences in the tissue concentrations of alkaline-earth metals of mussel populations to be more readily discerned.

Synthese und Kristallstrukturen von Diazadien-Komplexen der Erdalkalimetalle / Syntheses and Crystal Structures of Diazadiene Complexes of the Alkaline Earth Metals

1995 ◽  
Vol 50 (1) ◽  
pp. 71-75 ◽  
Author(s):  
Volker Lorenz ◽  
Bernhard Neumüller ◽  
Karl-Heinz Thiele
Keyword(s):  
Crystal Lattice ◽  
Crystal Structures ◽  
Structure Determination ◽  
Alkaline Earth ◽  
Alkaline Earth Metals ◽  
The Other ◽  
Calcium Atom ◽  
Space Group ◽  
X Ray ◽  
Moisture Sensitive

(DME)2] 1 (R = C6H4-4-CH3; DME = dimethoxyethane) was prepared by reaction of calcium with NR=CPh-CPh=NR in DME solution. The compound forms orange, moisture sensitive crystals, which were characterized by an X-ray structure determination [space group orthorhombic, P212121, Z = 4, 4634 observed unique reflections, R = 0.046; lattice dimensions at –70 °C: a = 1340.2(3), b = 1528.1(3), c = 1609.1(3) pm]. The calcium atom is coordinated by the four oxygen atoms of two chelating DME molecules and two nitrogen atoms of the diazadiene ligand, bonded in its enediamide form.[Ba2(DME)3(NPh–CPh=CPh–NPh)2 · DME] 3 was obtained from barium metal and NPh=CPh-CPh=NPh in DME solution as red crystals [space group monoclinic, P2l/c, Z = 4, 4000 observed unique reflections, R = 0.166; lattice dimensions at -70 °C: a = 1704.5(3), b = 1786.1(4), c = 2177.4(4) pm, β = 105.98(3)°]. The two barium atoms are bridged by two differently bonded diazadiene ligands (μ2-Ν,Ν′;μ-Ν, σ-Ν′). Additionally, one of the barium atoms is coordinated to two DME molecules and the other one to only one of the ether molecules. A further DME molecule is a constituent of the crystal lattice.

scholarly journals Reduction in Hybridization: Lone Pairs Interacting with Empty p Orbitals

2020 ◽  
Author(s):  
Edmund Doerkson ◽  
Ryan Fortenberry
Keyword(s):  
Bond Energy ◽  
Alkaline Earth ◽  
Lone Pair ◽  
Alkaline Earth Metals ◽  
The Other ◽  
Bond Energies ◽  
Hydrogen Atoms ◽  
Group 14 ◽  
Atom Increase ◽  
Planar Geometries

<div> <div> <div> <p>X−NH2 and X−OH (for X = Li, BeH, BH2, Na, MgH, and AlH2) exhibit a reduction in hybridization in the N and O atoms, and likely in F, as well. CCSD(T)-F12/cc-pVTZ-F12 optimizations for all combinations of atoms smaller than chlorine (excluding the noble gasses) where the standard valences are filled with hydrogen atoms give breaks in the expected periodic trends. While most bond energies for a given atom increase when bonded to all atoms across a given row in the period table, X−NH2, X−OH, and X−F actually have the strongest bonds with X = BH2 and AlH2. Furthermore, the buildup in bond energy from the alkali to alkaline-earth metals is steady, and the decrease to Group 14 and beyond is also steady. The interactions of X−NH2 and X−OH with X = Li, BeH, BH2, Na, MgH, and AlH2 also produce either linear or fully planar geometries. All of these factors imply that the lone pair on the N or O atoms are datively bonding with the empty <i>p</i> orbitals in the other atoms. This leads to a reduction in hybridization. The non-periodic strengths of these bonds have implications for the detection of molecules in space as well as in models for the formation of refractory molecules and condensation of mineral species in early stages of planet formation. </p> </div> </div> </div>

Fragment D Immunoreactivity: The Influence of Iodination and Calcium Environment

1979 ◽  
Author(s):  
B. Kudryfc ◽  
N. Blombäck
Keyword(s):  
Conformational Changes ◽  
Specific Antibody ◽  
Binding Sites ◽  
Specific Activity ◽  
High Specific Activity ◽  
The Other ◽  
Antigenic Determinants ◽  
Affinity Binding ◽  
Compact Structure ◽  
Chloramine T

Human fragment D (Fg-Ds) has been iodinated using both the Chloramine-T and lactoperoxidase methods. The specific activity was similar regardless of the method used. However, binding to a specific antibody was different for each preparation. The antigen labeled by the Chloramine-T method bound to a maximum of 40%, the other labeled product bound up to 85%. A correlation between the degree of immunoreactivity and avidity for a fibrinmonomer conjugate was found also. Fibrinmonomer bound about twice the amount of lactoperoxidase iodinated Fg-Ds as it did the Chloramine-T product. The use of these conjugates in the purification of immunoreactive Fg-Ds of high specific activity will be discussed. affinity binding sites for calcium have recently been demonstrated in fibrinogen. The presence of bound calcium is also believed to protect Fg-Ds from further digestion by plasmin. This is probably due to the formation of a more compact structure. However, conformational changes for calcium bound fibrinogen or Fg-Ds have not been observed. We tested the immunoreactivity of the lactoperoxidase iodinated Fg-Ds in presence and absence of calcium. Differences were found and this data suggests that some modification of antigenic determinants takes place as a consequence of calcium in the environment.

scholarly journals Study of the Interference effects of Aluminium on the Atom- And Ion-Lines of Alkaline Earth Metals in Aqueous Solutions Using an ICP Spectrometer with Axially Viewed Plasma

2015 ◽  
Vol 43 (1) ◽  
pp. 49-54
Author(s):  
Olivér Bánhidi
Keyword(s):  
Inductively Coupled Plasma ◽  
Alkaline Earth ◽  
Alkaline Earth Metals ◽  
The Other ◽  
Sample Introduction ◽  
Interference Effects ◽  
Spray Chamber ◽  
Inductively Coupled ◽  
Different Types ◽  
Sample Introduction Devices

Abstract The main advantage of inductively coupled plasma spectrometers with axially viewed plasma relative to the radially viewed plasma is the better detection power. The detection limits of the former are about 5-10 times lower than the latter. On the other hand, the axially viewed plasma has disadvantages. The most notable is the increased number of interference effects. In this paper, the study of the interference effects of aluminium on the atom- and ion-lines of alkaline earth metals are presented by examining different types of sample-introduction devices, such as a simple Meinhart-type concentric nebuliser, a V-groove nebuliser using a Sturman-Masters spray chamber, and an ultrasonic nebuliser

scholarly journals On the thermo-chemistry of flame spectra at high temperatures

1907 ◽  
Vol 79 (530) ◽  
pp. 242-261 ◽  
Keyword(s):  
High Temperature ◽  
Alkali Metals ◽  
Alkaline Earth ◽  
Alkaline Earth Metals ◽  
The Other ◽  
Lithium Nitrate ◽  
Metallic Elements ◽  
Present Communication ◽  
Complex Molecules ◽  
Band Spectra

The majority of the metallic elements have two distinct spectra, one of lines, the other of bands. In some spectra, bands are the most prominent feature in association with but few lines; in others the lines predominate over the bands. Of those substances with bands in their spectra there are many which may be reduced in quantity to almost a minimum without the bands disappearing from the flame or from the uncondensed spark; from this it would appear that there is a very intimate relationship between the bands and lines of the same element. It has been supposed that such bands as cannot be attributed to definite salts are the spectra of oxides or even of hydrides, but many facts have been accumulated from which it is evident that this is not correct. On the other hand, many of the elements which possess complex molecules may readily be understood to emit molecular or band spectra, but some further explanation is necessary when the molecule of the element is monatomic. The present communication deals only with one part of this subject, being merely a record of observations on high temperature flame reactions, and principally those of the alkali and alkaline earth metals. The spectra of the alkali metals at the highest temperature in the flame of the oxyhydrogen blow-pipe more nearly resemble those obtained from the arc than any other spectra of the same elements. Thus, all the lines of lithium photographed by Kayser and Runge in the arc have been obtained in the flame from lithium nitrate. This is evidence of the high temperature obtainable in the flame, but if further evidence were desired, we have it in the great facility with which both gold and silver can be vapourised and condensed from the vapour, the large number of arc lines of iron, practically all those that are reversible, which appear in the flame, and the volatilisation of palladium and iridium in weighable quantities.

scholarly journals Studies on the biosynthesis of quinones in fungi. Incorporation of 6-methylsalicylic acid into fumigatin and related compounds in Aspergillus fumigatus I.M.I. 89353

1965 ◽  
Vol 97 (2) ◽  
pp. 321-332 ◽  
Author(s):  
NM Packter
Keyword(s):  
Aspergillus Fumigatus ◽  
Specific Activity ◽  
High Specific Activity ◽  
The Other ◽  
Inhibitory Effects ◽  
Orsellinic Acid ◽  
Aromatic Components ◽  
Related Compounds

1. Orsellinic acid has been detected as a metabolite of Aspergillus fumigatus. 2. The other principal aromatic components of the medium are fumigatin and the quinol, fumigatol. Fumigatol has been shown to be dihydrofumigatin after oxidation to the quinone followed by acetylation. 3. (14)C-labelled 6-methylsalicylic acid can be hydroxylated in A. fumigatus to form orsellinic acid and decarboxylated to give m-cresol. 4. (14)C-labelled 6-methylsalicylic acid is incorporated into fumigatin and fumigatol (1.0-1.5%), but the conversion does not occur until about 2-3 days after supplementation of the medium. At this stage of growth, the organism has already synthesized approx. 20 times as much fumigatol as fumigatin and this ratio is reflected in the much lower specific activity of the quinol. 5. Supplementation of the medium with either orsellinic acid or orcinol, in addition to (14)C-labelled 6-methylsalicylic acid, greatly decreases the latter's incorporation into fumigatin. At the same time, the cultures containing these substances are stimulated to produce another quinone with relatively high specific activity. 6. 6-Methylsalicylic acid has not been detected in the medium of normal cultures. The results indicate that 6-methylsalicylic acid itself is not a direct precursor of fumigatin and fumigatol but that it is converted into a true intermediate, probably after hydroxylation to orsellinic acid. 7. Supplementation of the medium with 6-methylsalicylic acid (15-25mg./200ml.) greatly affects the metabolism of A. fumigatus. Growth is inhibited and the synthesis of fumigatol is markedly depressed in these cultures. The inhibitory effects may possibly be related in some way to the production of m-cresol.

scholarly journals STREPTOCOCCAL NUCLEASES

1967 ◽  
Vol 126 (3) ◽  
pp. 497-508 ◽  
Author(s):  
Lewis W. Wannamaker ◽  
Barbara Hayes ◽  
Walid Yasmineh
Keyword(s):  
Ribonucleic Acid ◽  
Specific Activity ◽  
High Specific Activity ◽  
The Other ◽  
Acid Inhibitor ◽  
Bacterial Rna ◽  
Zone Electrophoresis ◽  
Specific Activities ◽  
And Behavior ◽  
Deoxyribonuclease Activity

Preparations of streptococcal DNAse D with high specific activity and free of other streptococcal nucleases have been obtained by zone electrophoresis and column chromatography. Antisera prepared by injecting rabbits with such preparations specifically neutralize the activity of this enzyme. As with DNAse B, preparations of DNAse D regularly exhibit ribonuclease activity. For both B and D enzymes, the order of substrate preference is thymus DNA, yeast RNA, bacterial RNA; but the specific activity of the D enzyme is higher than that of the B enzyme with respect to thymus DNA and lower with respect to bacterial RNA. Both the deoxyribonuclease and the ribonuclease activities exhibited by preparations of both enzymes are inhibited by bacterial RNA, but approximately 100-fold greater concentrations of bacterial RNA are required to achieve inhibition of the deoxyribonuclease activity of the D enzyme equivalent to the inhibition of the B enzyme. The deoxyribonuclease activity of the D enzyme is also inhibited by yeast RNA, but even larger amounts are required. These observations indicate that the D enzyme is immunologically distinct from the other streptococcal nucleases and that it differs quantitatively from the B enzyme with respect to relative specific activities on different substrates and behavior in the presence of the bacterial ribonucleic acid inhibitor.

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