ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
Your search history is empty.
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
    facet.materialart.
    Unknown
    CRYSTAL STRUCTURE DETERMINATION OF A UNIQUE Nb-Ti-RICH THORITE FROM MONT SAINT-HILAIRE, QUEBEC, WITH COMMENTS ON 'THOROGUMMITE' (2013)
    Mineralogical Association of Canada
    Details
    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
    Published by Mineralogical Association of Canada
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 2
    facet.materialart.
    Unknown
    DISCREDITATION OF THOROGUMMITE (2015)
    Mineralogical Association of Canada
    Details
    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
    Published by Mineralogical Association of Canada
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 3
    facet.materialart.
    Unknown
    Mutagenesis and mapping of a mouse gene, Clock, essential for circadian behavior (1994)
    American Association for the Advancement of Science (AAAS)
    Details
    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
    Published by American Association for the Advancement of Science (AAAS)
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    PAPER CURRENT
  • 4
    Electronic Resource
    Electronic Resource
    Evidence for reaction of hydrogen iodide dimers with fluorine (1976)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 98 (1976), S. 1289-1290 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00421a054
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Lifetime of singlet oxygen in solution directly determined by laser spectroscopy (1982)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 104 (1982), S. 2065-2067 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00371a065
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Molecular beam chemistry. Unimolecular decomposition of chemically activated chlorobromoalkyl radicals (1973)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 95 (1973), S. 7889-7891 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00804a067
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Temperature dependence of picosecond time resolved fluorescence depletion measurements (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 6350-6356 
    Details
    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
    URL: http://dx.doi.org/10.1063/1.458977
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Picosecond fluorescence depletion spectroscopy. III. Intramolecular vibrational relaxation in the excited electronic state of p-cyclohexylaniline (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 1004-1014 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: This paper presents the results of the picosecond time-resolved study of intramolecular vibrational relaxation (IVR) in the molecule p-cyclohexylaniline. The results represent the second extensive study of a molecule using the technique which we have developed known as time-resolved fluorescence depletion (TRFD). Fluorescence depletion decays and dispersed fluorescence spectra of 19 S1 vibronic features are presented. The decays show a progression of dynamic behavior, including stationary behavior at low densities of states, quantum beating at intermediate densities, and fast decay of the initially prepared state at high state densities. The data allow us to assign IVR lifetimes which range from 250 ps at 820 cm−1 of excess vibrational energy to 2.2 ps at 2362 cm−1. Even at the highest frequencies we observe, the decays do not tend toward a simple exponential, but instead exhibit weak damped quantum beats.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458162
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Erratum: Picosecond fluorescence depletion spectroscopy. III. Intramolecular vibrational relaxation in the excited electronic state of p-cyclohexylaniline [J. Chem. Phys. 92, 1004 (1990)] (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 6337-6337 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458608
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    High resolution infrared laser induced fluorescence study of state mixing in methyl formate (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 6550-6552 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The total infrared fluorescence excitation spectrum in the region of the 101→212 rotational transition in the aldehyde C–H stretch fundamental band of methyl formate has been measured with a resolution of ∼0.007 cm−1. Five peaks were observed, indicating that the zeroth order optically active rovibrational state is mixed with nearly isoenergetic optically inactive bath states. This study marks the first use of a single mode optical parametric oscillator (OPO) for a spectroscopic experiment, and it demonstrates a technique with the potential to probe the vibrational makeup of individual molecular eigenstates.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.455726
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...