ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Publication Date: 2015-03-26
    Description: A bstract Thorogummite has been discredited as a valid mineral species. No type material from the original study was available for analysis. An extensive review of the literature, both recent and historic, reveals the use of the name "thorogummite" for any hydrated, metamict thorite or unidentified alteration product of a Th-bearing mineral. All early studies on "thorogummite" and other alteration products of thorite were performed on heterogeneous mixtures of mostly secondary and metamict materials and must be considered suspect. The validity of Frondel’s (1953) proposed (SiO 4 ) 4– (OH) 4 4– substitution between thorite and thorogummite was examined and shown to be an incomplete solid solution. All compositions in the literature to date are Th- and Si-dominant and must be considered thorite. Furthermore, the majority of the compositions in the literature are outdated and likely do not represent those from crystalline, single-phases. More likely, all so-called "thorogummite" are simply metastable hydrated or metamict thorite with varying volumes of other alteration products. The discreditation has been approved by the IMA Commission on New Minerals, Nomenclature and Classification (Nomenclature Voting proposal 14-B).
    Print ISSN: 0008-4476
    Topics: Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Publication Date: 2013-12-13
    Description: The crystal chemistry of a unique Nb-Ti-rich thorite from Mont Saint-Hilaire (Quebec) has been examined by a combination of single crystal and powder X-ray diffraction, electron microprobe analyses, and Fourier-transform infrared spectroscopy. The average of 9 compositions gave (Th 0.21 Nb 0.20 Ti 0.18 Ca 0.13 Y 0.10 REE 0.09 Fe 0.03 Zr 0.01 Sr 0.01 Mn 0.01 K 0.01 Na 0 . 01 ) 1.00 [(Si 0.49 0.41 Al 0.08 P 0.01 S 0.01 ) 1.00 (O 2.33 F 0.02 )](OH) 1.70 . This is the first example in the literature of a zircon-group mineral containing elevated concentrations of Nb (0.20 apfu , 13.33 wt.% Nb 2 O 5 ) and Ti (0.19 apfu Ti, 7.41 wt.% TiO 2 ), and evidence for the (SiO 4 ) 4– (OH) 4 4– "hydrogarnet" substitution. The crystal structure was solved and refined to R = 3.40% and wR 2 = 9.73% for 68 reflections with F o 〉 4( F o ). The studied thorite is slightly metamict, tetragonal, space group I 4 1 / amd , with a 7.058(1) Å, c 6.2260(12) Å, V 310.15(11) Å 3 , and Z = 4. It is isostructural with other zircon-group minerals and has a unit cell which is 4% smaller than that of thorite sensu stricto , a result of the incorporation of high field-strength elements of smaller radii. The structure consists of one eight-coordinated metal site ( A = Th, Zr, U, REE, Y, Nb, Ti, etc. ), one tetrahedral site ( T ), one O site, and one variably-occupied H site. The A site is coordinated by four axial O atoms [ A –O axial = 2.428(5) Å] and four equatorial O atoms [ A –O eq = 2.322(6) Å], which define a bisdisphenoid with 〈 A –O〉 = 2.374 Å. The T site in MSH thorite is only partially occupied by Si (33% vacant) and coordinated by four O with T –O = 1.641(5) Å. A partially occupied H site (31%) is located 0.980 Å away from the O atom, forming (O 4 H 4 ) 4– groups when the T site is vacant. Removal of the center of symmetry in the structure allows for the possibility of the presence of bimodal T –O and A –O bond lengths, leading to both short Si–O bonds and longer –OH bonds, as well as the shorter A –O bonds required for Nb and Ti. Accommodation of Nb and Ti into the thorite structure may be facilitated by increased distortion of the A O 8 bisdisphenoid, relaxation and shortening of A –O bonds as a result of the (SiO 4 ) 4– (OH) 4 4– substitution, and the likely presence of defects (O vacancies) in regions which have undergone slight metamictization, resulting in short-range ordering of Nb, Ti, and Th. Although it is possible that a metastable, limited solid solution exists between thorite and (OH) 4 4– -dominant "thorogummite" with intermediate compositions defined by Th(SiO 4 ) 1 –x (OH) 4 x , reported compositions indicate otherwise and it is suggested that the name "thorogummite" be abandoned.
    Print ISSN: 0008-4476
    Topics: Geosciences
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Publication Date: 1994-04-29
    Description: In a search for genes that regulate circadian rhythms in mammals, the progeny of mice treated with N-ethyl-N-nitrosourea (ENU) were screened for circadian clock mutations. A semidominant mutation, Clock, that lengthens circadian period and abolishes persistence of rhythmicity was identified. Clock segregated as a single gene that mapped to the midportion of mouse chromosome 5, a region syntenic to human chromosome 4. The power of ENU mutagenesis combined with the ability to clone murine genes by map position provides a generally applicable approach to study complex behavior in mammals.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3839659/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3839659/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Vitaterna, M H -- King, D P -- Chang, A M -- Kornhauser, J M -- Lowrey, P L -- McDonald, J D -- Dove, W F -- Pinto, L H -- Turek, F W -- Takahashi, J S -- P30-CA07175/CA/NCI NIH HHS/ -- R01-DK40493/DK/NIDDK NIH HHS/ -- T32 NS071040/NS/NINDS NIH HHS/ -- Howard Hughes Medical Institute/ -- etc. -- New York, N.Y. -- Science. 1994 Apr 29;264(5159):719-25.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Neurobiology and Physiology, Northwestern University, Evanston, IL 60208.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8171325" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; *Chromosome Mapping ; Chromosomes, Human, Pair 4 ; Circadian Rhythm/*genetics ; Ethylnitrosourea ; Female ; *Genes ; Genotype ; Humans ; Male ; Mice ; Mice, Inbred C57BL ; *Mutagenesis ; Phenotype
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 6350-6356 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: This paper presents the results of a temperature dependence study of time resolved fluorescence depletion (TRFD) measurements of intramolecular vibrational energy redistribution in the molecule p-cyclohexylaniline. TRFD scans of five vibrational bands of p-cyclohexylaniline were taken at several molecular beam conditions corresponding to rotational temperatures in the range of 8–110 K. The results are attributed to two possible coupling mechanisms and are shown to be consistent with previous work. Although rotational effects are probably dominant, our data also indicate that excitation of low (40 cm−1) vibrations may contribute to enhanced relaxation.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 7079-7086 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Stimulated emission pumping (SEP) spectroscopy has been used to investigate rovibrational level mixing in the ground singlet state of methyl glyoxal. A low resolution (0.35 cm−1) SEP survey spectrum allows accurate frequency assignments for 15 normal vibrations and seven hindered rotor levels. High resolution (0.05 cm−1) SEP spectra are reported for selected vibrational bands, including the fundamental vibrations of the symmetric carbonyl stretch and symmetric carbonyl bend. A van der Waals interaction between the neighboring carbonyl oxygen and methyl hydrogens is found to influence mixing of the carbonyl vibrations, affirming the results of previous studies.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The effects of rotation–torsion interactions on the rotational structure of torsional vibronic bands in an electronic spectrum are examined, and a computer program to calculate the relevant energies and transition intensities is described. Rotationally resolved type C bands in the 1nπ* spectrum of methylglyoxal are reported and interpreted. Since the torsional conformation of methylglyoxal differs in the two electronic states, a long progression of bands is observed, involving levels well below, near, and above the 190 cm−1 S1 torsional barrier. The rotation–torsion interaction increases rapidly towards the free rotor limit as the barrier is approached. Observed effects include energy shifts and the appearance of transitions forbidden by rigid rotor or torsional vibronic selection rules.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 98 (1976), S. 1289-1290 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...