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  • 1
    Electronic Resource
    Electronic Resource
    Molecular phylogeny of the free-living archezoanTrepomonas agilis and the nature of the first eukaryote (1996)
    Springer
    Journal of molecular evolution 43 (1996), S. 551-562 
    Details
    ISSN: 1432-1432
    Keywords: Diplozoa ; Cytostomes ; Diplokaryosis ; Trepomonas ; Ribosomal RNA phylogeny
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have sequenced the small ribosomal subunit RNA gene of the diplozoanTrepomonas agilis. This provides the first molecular information on a free-living archezoan. We have performed a phylogenetic analysis by maximum likelihood, parsimony, and distance methods for all available nearly complete archezoan small subunit ribosomal RNA genes and for representatives of all major groups of more advanced eukaryotes (metakaryotes). These show Diplozoa as the earliest-diverging eukaryotic lineage, closely followed by microsporidia.Trepomonas proves to be much more closely related toHexamita, and, to a lesser degree, toSpironucleus, than toGiardia. The close relationship between the free-livingTrepomonas on our trees and the parasitesHexamita inflata andSpironucleus refutes the idea that the early divergence of the amitochondrial Archezoa is an artefact caused by parasitism. The deep molecular divergence between the three phagotrophic genera with two cytostomes (Hexamita, Trepomonas, Spironucleus) and the saprotrophicGiardia that lacks cytostomes is in keeping with the classical evidence for a fundamental difference in the symmetry of the cytoskeleton between the two groups. We accordingly separate the two groups as two orders: Distomatida for those with two cytostomes/cytopharynxes and Giardiida ord. nov. forGiardia andOctomitus that lack these, and divide each order into two families. We suggest that this fundamental divergence in manner of feeding and in the symmetry of the cytoskeleton evolved in a free-living diplozoan very early indeed in the evolution of the eukaryotic cell, possibly very soon after the origin of the diplokaryotic state (having two nuclei linked together firmly by the cytoskeleton) and before the evolution of parasitism by distomatids and giardiids, which may have colonized animal guts independently. We discuss the possible relationship between the two archezoan phyla (Metamonada and Microsporidia) and the nature of the first eukaryotic cell in the light of our results and other recent molecular data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02202103
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  • 2
    Electronic Resource
    Electronic Resource
    On resolving hot carrier induced degradation mechanisms in silicon-on-sapphire metal-oxide-semiconductor field-effect transistors (1993)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 1912-1914 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Hot carrier induced damage in silicon-on-sapphire (SOS) metal-oxide-semiconductor field-effect transistors (MOSFETs) are reported. Various experimental techniques—the peak linear-region transconductance change, extrapolated threshold voltage shift, exponent in time dependence of transconductance, and charge pumping current—are employed to explore the degradation mechanisms. Hot light holes alone in silicon-on-sapphire MOSFETs are found ineffective in generating interface states, but their interaction with trapped electrons are.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.110646
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  • 3
    Electronic Resource
    Electronic Resource
    The preparation and reactions of esters of dichloromethaneboronic acid
    Amsterdam : Elsevier
    Journal of Organometallic Chemistry 122 (1976), S. 145-149 
    Details
    ISSN: 0022-328X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/S0022-328X(00)80606-3
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  • 4
    Electronic Resource
    Electronic Resource
    The effect of bead diameter on the accuracy of two current techniques used to quantify bone ingrowth in porous-coated implants (1994)
    Springer
    Journal of materials science 5 (1994), S. 29-32 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: The effect of the bead diameter on the accuracy of two techniques used in bone ingrowth quantification, microradiography and backscattered electron imaging-scanning electron microscopy (BEI-SEM), was assessed using porous-coated implants. Two groups of seven titanium porous implants (group A: bead size 250–350 μm and group B: 500–700 μm) were implanted for 12 weeks in a canine model. After euthanasia, the same histological slides were prepared for microradiography and BEI-SEM. The percentage of bone, bone ingrowth, bone ongrowth, porosity and bone index were determined by a point counting method using images from both techniques. ANOVA and Tukey's test were used to compare the results from the different bead sizes and techniques. The results showed significant higher bone ingrowth in microradiography groups, and significant lower porosity in only the fine-bead microradiography group (group A size). Microradiography also obtained significantly higher bone ongrowth, but only for the coarse bead size group (group B). From these results it was concluded that microradiography decreases the porosity of the porous coating compared with BEI-SEM. This effect seems to be dependent on the bead diameter. The smaller the diameter, the greater the effect. Furthermore, microradiography increases bone ingrowth which seems to be affected independently of the bead diameter, becoming the most sensitive parameter to increase.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00121150
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  • 5
    Electronic Resource
    Electronic Resource
    Bone ingrowth analysis and interface evaluation of hydroxyapatite coated versus uncoated titanium porous bone implants (1994)
    Springer
    Journal of materials science 5 (1994), S. 411-416 
    Details
    ISSN: 1573-4838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Fourteen titanium porous-coated implants with a cylindrical shape (length 22 mm and diameter 5±0.3 mm) were prepared. Bead size was 250–350 μm. Seven implants were plasma-sprayed with hydroxyapatite and the other seven remained uncoated. Implants, both hydroxyapatite-coated and uncoated, were randomly selected and press fitted longitudinally into the proximal femoral cancellous bone bilaterally in seven dogs. After 12 weeks the dogs were euthanized and push-out and histomorphometric backscattered electron microscopy studies were carried out. No statistical differences in the mechanical tests were observed. Comparing hydroxyapatite-coated versus uncoated implants, the histomorphometric results showed statistical significance in the percentage of bone (p=0.01); and in bone index, ratio between bone ingrowth and bone ongrowth (p=0.01). The size of the bone implant interface was smaller in the hydroxyapatite applied to spherical bead titanium porous coatings were demonstrated. These morphological and histomorphometric results support the concepts involved with the use of hydroxyapatite as a coating for uncemented porous prosthetic devices.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00058975
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  • 6
    Electronic Resource
    Electronic Resource
    Stereoselective detection of amino acids by lobster olfactory receptor neurons (1993)
    Springer
    Journal of comparative physiology 171 (1993), S. 705-712 
    Details
    ISSN: 1432-1351
    Keywords: Olfaction ; Amino acid ; Receptor binding ; Electrophysiology ; Lobster
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. Biochemical and electrophysiological assays were used to test the hypothesis that the olfactory system of the Caribbean spiny lobster, Panulirus argus, contains populations of chemosensory receptors that are differentially sensitive to the L- and D-stereoisomers of the amino acid alanine. 2. Independent binding sites for L-alanine (dissociation constant (K d ) of 6.6 μM and maximum binding (Bmax) of 16.8 fmole/μg protein) and for D-alanine (K d of 21.6 μM and Bmax of 17.8 fmole/μg protein) were characterized biochemically. The interaction of ligand with each binding site is rapid, reversible and saturable with respect to both time and concentration. 3. Based on a difference of at least 20% in the relative sensitivity of an olfactory receptor cell to alanine enantiomers, 44% and 34% of the 77 neurons tested were classified as L-alanine and D-alanine sensitive, respectively. The relative sensitivity to alanine enantiomers was independent of the concentration tested. Stereoselective receptors are likely for 17 of 20 other amino acids tested. 4. The congruence of biochemical and electrophysiological results leads to the conclusion that the lobster's responses to D- and L-alanine are mediated by receptors specific for each stereoisomer and that the receptors are differentially distributed among receptor cells.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00213067
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  • 7
    Electronic Resource
    Electronic Resource
    Raman spectrum of natural and synthetic stishovite (1986)
    Springer
    Physics and chemistry of minerals 13 (1986), S. 285-290 
    Details
    ISSN: 1432-2021
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Abstract Raman spectra of natural and synthetic samples of stishovite have been measured with a micro-optical spectrometer system. These spectra have a pattern that is characteristic of rutile-structured oxides. The spectrum of synthetic stishovite is characterized by well-resolved bands at 231, 589, 753, and 967 cm−1, which are assigned as theB 1g,E g,A 1g, andB 2g fundamentals, respectively, of the first-order Raman spectrum of the ideal, ordered structure. Natural stishovite obtained from Meteor Crater, Arizona has a first-order Raman spectrum that is fully consistent with that of the synthetic material. The observed spectrum of the natural sample, however, is weaker and has bands in addition to those identified as fundamentals in the spectrum of the synthetic material. A broad band at ∼475 cm−1 may be indicative of glass or contaminants derived from the extraction procedure. Alternatively, this band may arise from multiphonon scattering that is enhanced by poor crystallinity or structural disorder in the natural shocked sample.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00308345
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  • 8
    Electronic Resource
    Electronic Resource
    The appearances of wear on polyethylene - a comparison of in vivo and in vitro wear surfaces (1978)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 12 (1978), S. 317-335 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: An examination has been made of the wear surfaces of 21 ultra-high-molecular-weight polyethylene components of hip and knee joint prostheses removed from patients. Both light optics and scanning electron microscope systems of examination have been used. The appearances are compared with specimens subjected to two different in vitro wear tests. Surface appearances related to the wear experience have been classified into seven modes. At least four of these are evidences of what may be four different wear mechanisms. Entrapment of bone-cement particles between articulating surfaces is fundamentally extraneous but is seen to generate the most severe wear. In the absence of bone-cement particles, in vivo, wear seems to be mild. Wear in vitro produces similar surface modes but with different relative emphasis.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820120306
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  • 9
    Electronic Resource
    Electronic Resource
    Defects in failed stems of hip prostheses (1978)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Biomedical Materials Research 12 (1978), S. 635-651 
    Details
    ISSN: 0021-9304
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Medicine , Technology
    Notes: A study has been made of the fractures and associated material from 34 prostheses broken in service. All the fractures appear to be of the fatigue type. Search by me-tallographic analysis for cracklike generating defects in material near the fracture reveals such conditions as abnormally coarse crystals, large nonmetallic inclusions, large inclusion population, undissolved master alloy particles, abnormal carbide segregation, interdendritic segregation, shrinkage, and gas porosity. Recommendations are made for the choice of metallic alloys for femoral stem application.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jbm.820120506
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  • 10
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    Construction and characterization of Moloney murine leukemia virus mutants unable to synthesize glycosylated gag polyprotein. (1983)
    National Academy of Sciences
    Details
    Publication Date: 1983-10-01
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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