1,485 research outputs found
Ferroelectric Nanotubes
We report the independent invention of ferroelectric nanotubes from groups in
several countries. Devices have been made with three different materials: lead
zirconate-titanate PbZr1-xTixO3 (PZT); barium titanate BaTiO3; and strontium
bismuth tantalate SrBi2Ta2O9 (SBT). Several different deposition techniques
have been used successfully, including misted CSD (chemical solution
deposition) and pore wetting. Ferroelectric hysteresis and high optical
nonlinearity have been demonstrated. The structures are analyzed via SEM, TEM,
XRD, AFM (piezo-mode), and SHG. Applications to trenching in Si dynamic random
access memories, ink-jet printers, and photonic devices are discussed.
Ferroelectric filled pores as small as 20 nm in diameter have been studied
Fluorescence kinetics of flavin adenine dinucleotide in different microenvironments
Fluorescence kinetics of flavin adenine dinucleotide was measured in a wide time and spectral range in different media, affecting its intra- end extramolecular interactions, and analyzed by a new method based on compressed sensing
Theoretical Study on Transport Properties of Normal Metal - Zigzag Graphene Nanoribbon - Normal Metal Junctions
We investigate transport properties of the junctions in which the graphene
nanoribbon with the zigzag shaped edges consisting of the legs is
sandwiched by the two normal metals by means of recursive Green's function
method. The conductance and the transmission probabilities are found to have
the remarkable properties depending on the parity of . The singular
behaviors close to E=0 with being the Fermi energy are demonstrated. The
channel filtering is shown to occur in the case with even.Comment: 4 pages, 5 figure
Identification of distinct loci for de novo DNA methylation by DNMT3A and DNMT3B during mammalian development
De novo establishment of DNA methylation is accomplished by DNMT3A and DNMT3B. Here, we analyze de novo DNA methylation in mouse embryonic fibroblasts (2i-MEFs) derived from DNA-hypomethylated 2i/L ES cells with genetic ablation of Dnmt3a or Dnmt3b. We identify 355 and 333 uniquely unmethylated genes in Dnmt3a and Dnmt3b knockout (KO) 2i-MEFs, respectively. We find that Dnmt3a is exclusively required for de novo methylation at both TSS regions and gene bodies of Polycomb group (PcG) target developmental genes, while Dnmt3b has a dominant role on the X chromosome. Consistent with this, tissue-specific DNA methylation at PcG target genes is substantially reduced in Dnmt3a KO embryos. Finally, we find that human patients with DNMT3 mutations exhibit reduced DNA methylation at regions that are hypomethylated in Dnmt3 KO 2i-MEFs. In conclusion, here we report a set of unique de novo DNA methylation target sites for both DNMT3 enzymes during mammalian development that overlap with hypomethylated sites in human patients
Photoproduction of eta-mesons on the deuteron above S11(1535) in the presence of a narrow P11(1670) resonance
Incoherent photoproduction of eta-mesons on the deuteron is considered. The
main attention is paid to the region above the S11(1535) resonance where rather
narrow resonance like structure in the total cross section extracted for gamma
n -> eta n has been reported. The corresponding experimental results are
analyzed from the phenomenological standpoint within the model containing a
baryon P11 with the mass about 1670 MeV and a width less than 30 MeV. This
resonance was suggested in some recent works as a nonstrange member of the
pentaquark antidecuplet with J^P=1/2^+. The calculation is also performed for
the polarized and nonpolarized angular distributions of mesons. In
addition, we present our predictions for the cross sections of the neutral
kaons and double pion photoproduction, where the same narrow P11(1670)
resonance is assumed to contribute through the decay into K^0 Lambda and pi
Delta configuration.Comment: 11 pages, 5 figure
On the background in the reaction and mixed event simulation
In this paper we evaluate sources of background for the , with the detected through its decay channel, to
compare with the experiment carried out at ELSA. We find background from
followed by decay of a into two ,
recombining one and one , and from the reaction with subsequent decay of the into two photons. This
background accounts for the data at invariant masses beyond 700
MeV, but strength is missing at lower invariant masses which was attributed to
photon misidentification events, which we simulate to get a good reproduction
of the experimental background. Once this is done, we perform an event mixing
simulation to reproduce the calculated background and we find that the method
provides a good description of the background at low invariant
masses but fakes the background at high invariant masses, making background
events at low invariant masses, which are due to misidentification
events, responsible for the background at high invariant masses which is due to
the and reactions.Comment: 10 pages, 5 figure
One-neutron knockout reaction of 17C on a hydrogen target at 70 MeV/nucleon
First experimental evidence of the population of the first 2- state in 16C
above the neutron threshold is obtained by neutron knockout from 17C on a
hydrogen target. The invariant mass method combined with in-beam gamma-ray
detection is used to locate the state at 5.45(1) MeV. Comparison of its
populating cross section and parallel momentum distribution with a Glauber
model calculation utilizing the shell-model spectroscopic factor confirms the
core-neutron removal nature of this state. Additionally, a previously known
unbound state at 6.11 MeV and a new state at 6.28(2) MeV are observed. The
position of the first 2- state, which belongs to a member of the lowest-lying
p-sd cross shell transition, is reasonably well described by the shell-model
calculation using the WBT interaction.Comment: 15 pages, 3 figure
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