931 research outputs found
Synthesis and reactivity of tricarbonyl(1-methoxycarbonyl-5-phenylpentadienyl)iron(1+) cation
Tricarbonyl(1-methoxycarbonyl-5-phenylpentadienyl)iron(1+) hexafluorophosphate (7) was prepared in two steps from tricarbonyl(methyl 6-oxo-2,4-hexadienoate)iron. While addition of carbon and heteroatom nucleophiles to 7 generally occurs at the phenyl-substituted dienyl carbon to afford (2,4-dienoate)iron products, the addition of phthalimide proceeded at C2 to afford a (pentenediyl)iron product (18). Complex 18 was structurally characterized by X-ray diffraction analysis.
The reaction of the title cation with carbon and heteroatom nucleophiles was examined. In general, the products arise from nucleophilic attack at C5 to give E,E- or E,Z-dienoate iron complexes. Addition of phthalimide anion proceeds at C2 of the cation to afford a (pentenediyl)iron complex, whose structure was confirmed by X-ray diffraction analysis
The nature of iron-oxygen vacancy defect centers in PbTiO3
The iron(III) center in ferroelectric PbTiO3 together with an oxygen vacancy
forms a charged defect associate, oriented along the crystallographic c-axis.
Its microscopic structure has been analyzed in detail comparing results from a
semi-empirical Newman superposition model analysis based on finestructure data
and from calculations using density functional theory.
Both methods give evidence for a substitution of Fe3+ for Ti4+ as an acceptor
center. The position of the iron ion in the ferroelectric phase is found to be
similar to the B-site in the paraelectric phase. Partial charge compensation is
locally provided by a directly coordinated oxygen vacancy.
Using high-resolution synchrotron powder diffraction, it was verified that
lead titanate remains tetragonal down to 12 K, exhibiting a c/a-ratio of
1.0721.Comment: 11 pages, 5 figures, accepted in Phys. Rev.
Exome Sequence Analysis of 14 Families With High Myopia
PURPOSE: To identify causal gene mutations in 14 families with autosomal dominant (AD) high myopia using exome sequencing. METHODS: Select individuals from 14 large Caucasian families with high myopia were exome sequenced. Gene variants were filtered to identify potential pathogenic changes. Sanger sequencing was used to confirm variants in original DNA, and to test for disease cosegregation in additional family members. Candidate genes and chromosomal loci previously associated with myopic refractive error and its endophenotypes were comprehensively screened. RESULTS: In 14 high myopia families, we identified 73 rare and 31 novel gene variants as candidates for pathogenicity. In seven of these families, two of the novel and eight of the rare variants were within known myopia loci. A total of 104 heterozygous nonsynonymous rare variants in 104 genes were identified in 10 out of 14 probands. Each variant cosegregated with affection status. No rare variants were identified in genes known to cause myopia or in genes closest to published genome-wide association study association signals for refractive error or its endophenotypes. CONCLUSIONS: Whole exome sequencing was performed to determine gene variants implicated in the pathogenesis of AD high myopia. This study provides new genes for consideration in the pathogenesis of high myopia, and may aid in the development of genetic profiling of those at greatest risk for attendant ocular morbidities of this disorder
New Speakers and Language Revitalisation: Arpitan and Community (Re)formation
Today, it is uncontroversial to claim that France’s regional (minority) languages (RLs) are in decline. However, revitalisation movements have nonetheless continued to surface, and this chapter considers one by-product of such efforts: the emergence of new speakers in RL contexts. The term ‘new speaker’ refers to individuals who acquire the target language not through traditional transmission contexts (e.g. home, family), but instead as adults through language revitalisation initiatives. The chapter focuses on revitalisation efforts in the context of Francoprovençal, a severely endangered and understudied RL spoken transnationally across French, Italian and Swiss borders. A critical examination of current studies supplemented with recently collected empirical data shows new speakers to be central agents in a movement championing proto-nation-statehood across national borders, reorienting the region’s traditional sociolinguistic field
Search for the radiative transitions and
By using a 2.92 fb data sample taken at GeV with
the BESIII detector operating at the BEPCII collider, we search for the
radiative transitions and
through the hadronic decays . No
significant excess of signal events above background is observed. We set upper
limits at a 90% confidence level for the product branching fractions to be
and
. Combining our result with world-average
values of , we find the
branching fractions
and at a 90%
confidence level.Comment: 10 pages, 4 figure
Precision Measurement of the Mass of the Lepton
An energy scan near the pair production threshold has been performed
using the BESIII detector. About pb of data, distributed over four
scan points, was collected. This analysis is based on pair decays to
, , , , , , , and
final states, where denotes a charged or . The mass of the
lepton is measured from a maximum likelihood fit to the pair production
cross section data to be )
MeV/, which is currently the most precise value in a single measurement.Comment: 13 pages, 7 figure
Observation of at BESIII
Using events collected with the BESIII detector
at the BEPCII storage rings, we observe for the first time the process
,
with a significance of ( including systematic
uncertainties). The product branching fraction of is measured to be
, where the first error is statistical and the
second is systematic. This measurement provides information on the
production near threshold coupling to and improves the understanding
of the dynamics of decays to four body processes.Comment: 8 pages, 7 figure
Search for C-parity violation in and
Using events recorded in
collisions at 3.686 GeV with the BESIII at the BEPCII collider, we
present searches for C-parity violation in and decays via . No significant
signals are observed in either channel. Upper limits on the branching fractions
are set to be and
at the 90\%
confidence level. The former is one order of magnitude more stringent than the
previous upper limit, and the latter represents the first limit on this decay
channel.Comment: 7 pages, 2 figure
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