Labile Elements Research Articles

Chemical studies of differentiated meteorites: I. Labile trace elements in Antarctic and non-Antarctic eucrites

We report data for Ag, Au, Bi, Cd, Co, Cs, Ga, In, Rb, Sb, Se, Te, Tl, U, and Zn determined by RNAA in 25 Antarctic and 9 non-Antarctic eucrites (including the cumulate eucrites Moore Co. and Serra de Magé). Compositional variations for a given element in a population range from <10% for Ga to ~200× for Ag, Au, Bi, In, or Tl. Highly incompatible, refractory elements like U are well known to exceed Cl levels in eucrites because of their igneous origin. Surprisingly, contents of highly labile elements can also be quite high, sometimes at 0.1 × Cl, I.E., levels more like chondritic. However, a carbonaceous chondrite pattern (the most likely admixture possibility) is not apparent since Cl-normalized trace element data for a given eucrite sample do not match the flat trends known for carbonaceous chondrites. The Unormalized contents of most elements indicate a thermal (vapor/solid) process accompanied in the case of lithophiles Rb and Cs by a geochemical fractionation. For these, or Ag, Bi, Cd, or Tl (elements with ionic radii and charges resembling those of incompatible elements), Antarctic and non-Antarctic noncumulate eucrites lie on the same trend line, indicating that all derive from the same parent. The thermal process responsible for the U-normalized trend could involve devolatilization of eucrite parent material or, as we prefer because of other data, condensation of volcanic emanations to differing degrees on preexisting eucrite (and diogenite and howardite) parent rocks. Antarctic eucrites have different—usually higher—contents of labile elements, particularly Tl, than do non-Antarctic eucrites. The difference seems not to be due to the terrestrial history of the samples but, rather, is preterrestrial in origin. By our preferred scenario, Antarctic eucrites received a greater average complement of mobile elements, hence, were presumably cooler (and nearer the surface of the eucrite parent body) than were non-Antarctic eucrites.

Meteorites and the early solar system : January 6–9, 1987 Tucson, Arizona

The present work discusses topics in the source regions for meteorites, their secondary processing, irradiation effects on meteorites, solar system chronology, the early solar system, the chemistry of chondrites and the early solar system, magnetic fields in the early solar system, the nature of chondrules, micrometeorites, inhomogeneity of the nebula, the survival of presolar material in meteorites, nucleosynthesis, and the relationship between extinct radionuclides and nucleocosmochronology. Attention is given to igneous activity in the early solar system, principles of radiometric aging, the cosmochemical classification of the elements, highly labile elements, the potential significance of pristine material, the astrophysical implications of presolar grains, boundary conditions for the origin of the solar system, and iodine-xenon dating.

Homologous genes encode two distinct histidine-rich proteins in a cloned isolate of Plasmodium falciparum.

Two genes encoding distinct histidine-rich proteins in a Plasmodium falciparum clone exhibit high levels of homology, suggesting they have originated by duplication and divergence from a common ancestral sequence. Both genes have a similar interrupted structure and an exon that encodes closely related tandem repeats of very high histidine and alanine content. The most common repeat encoded by one gene, the hexapeptide Ala-His-His-Ala-Ala-Asp, differs in the sixth position from the most common repeat encoded by the other gene, the hexapeptide Ala-His-His-Ala-Ala-Asn. The divergence of the repeat domains is greater than that of the flanking regions, which exhibit 85-90% homology, including untranslated sequences. This suggests the tandem repeats are relatively labile elements within the genome that may provide the parasite with a means of rapid evolutionary change.

An inexpensive device for freeze drying and plastic embedding tissues at low temperatures.

The preparation of biological tissues for electron microscopy by rapid freezing retains the original localization of ions and molecules. A reproducible freezing regime was established by quenching tissues in liquid propane according to the method of Elder et al. (1981). Tissue was thereafter freeze dried in a custom built freeze drying device with a liquid nitrogen cooled stage to prevent ice recrystallization during drying. The device was also designed to allow the vacuum embedding of tissue in low temperature resin such as Lowicryl and polymerization in situ. This paper describes the design of the device and an example of its use in the freeze drying of cartilage. The results show that minimal ice damage occurs to the chondrocytes and that intracellular organelles are clearly visible. The regime described may prove a useful and pragmatic alternative to cutting tissue in the frozen state. Translocation of elements is unlikely except perhaps in the case of very labile elements such as Na and K, but this remains to be fully elucidated.

Flux comparisons between sediments and sediment traps in the eastern tropical Pacific: Implications for atmospheric C02 variations during the Pleistocene1

Regeneration rates of labile elements and biogenic components were measured at two sites in the Guatemala Basin by comparing fluxes of material caught in sediment traps to fluxes of that preserved in the sediments. From 95 to 99% of the N, P, organic C, CaCO3, opal, and Br reaching the sea floor are regenerated at the two sites. For elements bound largely in refractory phases (e.g. Al, Sc, Ti, and Fe), the particle‐associated flux to the bottom is within 20% of the accumulation rate in the sediment.The two MANOP sites, about 800 km apart, have similar fluxes of organically associated N, P, and C, reflecting similar and relatively high primary productivity. There is a marked contrast in the opal/carbonate fluxes which leads to differences in CO2 cycling at the two locations. At least 95% of the total particulate organic carbon and &gt;97% of the total particulate phosphate are regenerated at &lt;1,500‐m depth in the oceans. In contrast, much of the CaCO3 is destroyed at the sea floor. By a simple three‐box ocean model we show that the recycling and storage depths of organic C, CaCO3, and P can be important factors in the control of the CO2 content of the atmosphere. We suggest that Pleistocene CO2 variations were due in part to global increases in upwelling during glacial periods with synchronous increases in total oceanic productivity and differences in diatom vs. carbonate productivity.

A rapid, routine technique for the X-ray microanalysis of microincinerated cryosections: an SEM study of inorganic deposits in tissues of the marine gastropod Littorina littorea (L.).

A procedure is described that prepares chemically untreated biological sections for X-ray microanalysis in the scanning electron microscope (SEM). The method aims to retain and localize labile components in tissue sections by a procedure that is both rapid and routine. Large quantities of fresh tissue can be processed for analysis within a single day. Thick cryosections are cut with a steel knife in a conventional cryostat, freeze-dried, and then ashed by either low or high temperature incineration procedures. Controlled microincineration attenuates the organic matrix to reveal sufficient surface relief for effective SEM of some cytological structure and microanalysis of the residual inorganic components. The detectability of various elements is enhanced because the relative concentrations in the residues are increased and the level of nonspecific background in the X-ray spectra is reduced. The technique is applied to different tissues from the visceral complex of the marine prosobranch Littorina littorea. In animals exposed to elevated levels of zinc it can be demonstrated tht the metal is localized both as an insoluble form in granules and as a labile form within the cytoplasm. Other metals, including magnesium, potassium, calcium, manganese, and iron, have been identified and localized. The effectiveness of this technique for retaining labile elements is compared, in outline, with that of conventional fixation procedures.

Lunar bulk sample trace element contents and kreep

The geochemical coherence between the labile element Cl and more refractory F, K, REE and P in lunar soils is utilized to gain insight into the evolution of the lunar samples studied.

Histochemical stability in freeze-desiccated tissue sections

Summary Freeze-desiccation of fresh cryostat sections is carried out by briefly air-drying fresh cryostat sections on a coverslip and then placing serial sections in a 4-oz wide mouth jar containing 2 to 3 g of CaSO 4 , sealing the jars, and storing them in a freezer. Histochemical tests repeated on the stored cryostat sections showed that some enzymes are relatively stable, while others are almost totally lost. The reaction for a trypsin-like enzyme (naphthol AS) in mast cells was stable in over 300 freeze-desiccated specimens, some of which were in storage up to 5 years. Six dehydrogenase reactions in five specimens varied from total retention to almost complete loss of activity. Two hydrolytic enzymes showed moderate loss of activity. Slight morphological alteration of the tissue is produced by freeze-desiccation storage, especially if the jars are inadequately sealed. Freeze-desiccation storage is one method for maintaining a supply of cryostat sections which have not been subjected to any fixatives. This enables the investigator to attempt new histochemical procedures or repeat certain procedures previously carried out. Some of the conditions to be considered before employing this technique are: 1) availability of specific types of tissues; 2) availability of liquid nitrogen storage facilities; 3) satisfactory completion of tests for very labile enzymes or elements.

The Providence Hospital Blood Conservation Program

In 1953, the Medical Staff adopted in its bylaws “Indications for Blood Transfusion,” which are in brief as follows: 1. To replace needed whole blood volume; 2. For oxygen transport, (A) Anemic patient, otherwise well, must have seven or less Gm. per cent of hemoglobin, (B) Anemic patient with complications affecting oxygenation or is to undergo anesthesia may be transfused if the hemoglobin is less than 10 Gm. per cent; 3. Exchange transfusion, and 4. Fresh whole blood is indicated only in rare instances of dyscrasias where a labile element is important. In the period from 1953 to 1960, the application of these indications has resulted in a decreasing “use factor” (units transfused annually divided by the number of patients) from 0.237 to 0.110. The benefits achieved are the following: Limits the transfusions to patients having valid medical indications, protects the patients from the hazards of unnecessary transfusions, and eases the burden of donor recruitment and blood collection.

The electrophoretic properties of red blood cells after reaction with influenza virus hemagglutinin

1. 1. The mobilities of guinea pig red blood cells subjected to the action of PR8 influenza type A virus hemagglutinin have been measured at several values of pH and ionic strength ( pH 7.9−5.7, Γ 2 0.172−0.0043 ). 2. 2. The negative surface charge density of “treated” cells is usually less than that of control cells under similar conditions; at pH 7 and physiological ionic strength the difference amounts to about 1000 e.s.u. or 2 × 10 12 electrons/sq. cm. 3. 3. The reciprocal surface charge density of treated cells varies linearly with reciprocal ionic strength; the slope K is almost the same as for control cells. 4. 4. The charge density of treated cells becomes sensitive to pH at low ionic strengths; the resulting curves are quite similar to those of control cells under the same conditions, but with a constant displacement in the direction of a smaller net negative charge density. 5. 5. The changes associated with receptor decomposition are attributed to the formation of free cationic groups comparable to those formed by the action of RDE upon Tamm and Horsfall's urinary inhibitor. 6. 6. It is suggested on the basis of rough calculations that the red blood cell receptor for influenza A virus consists of a single molecule comparable to the urinary inhibitor. 7. 7. Since the supplementary positive charge on the red blood cell produced by virus action varies with ionic strength in the same manner as the net negative charge of the untreated cell, it is assumed to be attached to the same labile elements of the cell membrane and to participate in the same structural rearrangement brought about by decreased ionic strength.

THE LABILE ELEMENT OF HYPERTENSION

Medical Journal of AustraliaVolume 2, Issue 8 p. 290-291 Current Comment THE LABILE ELEMENT OF HYPERTENSION First published: 01 August 1949 https://doi.org/10.5694/j.1326-5377.1949.tb36847.xAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article. Volume2, Issue8August 1949Pages 290-291 RelatedInformation