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Strain amplitude response and the microstructure of PA/clay nanocomposites
Polyamide 6/clay nanocomposites (PAn, where n is the mass fraction of clay) with various clay loading were prepared by melt compounding in a twin screw extruder. Exfoliation of clay in a PA matrix was confirmed by X-ray diffraction. Strain amplitude response of PAn in both melt and solution states has been investigated. In the melt state, critical strain amplitude of PAn is sensitive to strain amplitude response and decrease logarithmically with increasing clay loading. The elastic moduli (G′) of PAn are reversible under frequency loop sweeps. Comparisons of strain amplitude response in both melt and solution states have been conducted. Two different responses have been observed: strain thinning in the melt state and weak strain overshoot in the solution state. FTIR studies show that amide II band of PAn shifts toward high wavenumbers, but amide I band and N–H stretching vibration are independent of clay loading. We suggest that two types of strain amplitude response of PAn can be explained: strain thinning which is dominant in PAn caused by physical adsorption and entanglement of PA chains on nanoclays and weak strain overshoot caused by weak bonds between PA chains and nanoclays
Matter wave soliton bouncer
Dynamics of a matter wave soliton bouncing on the reflecting surface (atomic
mirror) under the effect of gravity has been studied by analytical and
numerical means. The analytical description is based on the variational
approach. Resonant oscillations of the soliton's center of mass and width,
induced by appropriate modulation of the atomic scattering length and the slope
of the linear potential are analyzed. In numerical experiments we observe the
Fermi type acceleration of the soliton when the vertical position of the
reflecting surface is periodically varied in time. Analytical predictions are
compared with the results of numerical simulations of the Gross-Pitaevskii
equation and qualitative agreement between them is found.Comment: 8 pages, 5 figure
Destruction of valence-bond order in a sawtooth chain with a Dzyaloshinskii-Moriya term
A small value of the spin gap in quantum antiferromagnets with strong
frustration makes them susceptible to nominally small deviations from the ideal
Heisenberg model. One of such perturbations, the anisotropic
Dzyaloshinskii-Moriya interaction, is an important perturbation for the
kagome antiferromagnet, one of the current candidates for a quantum-disordered
ground state. We study the influence of the DM term in a related
one-dimensional system, the sawtooth chain that has valence-bond order in its
ground state. Through a combination of analytical and numerical methods, we
show that a relatively weak DM coupling, , is sufficient to destroy the
valence-bond order, close the spin gap, and turn the system into a Luttinger
liquid with algebraic spin correlations. A similar mechanism may be at work in
the kagome antiferromagnet.Comment: 11 pages. References added. Revisions made as requested by referee
Disordered locality in loop quantum gravity states
We show that loop quantum gravity suffers from a potential problem with
non-locality, coming from a mismatch between micro-locality, as defined by the
combinatorial structures of their microscopic states, and macro-locality,
defined by the metric which emerges from the low energy limit. As a result, the
low energy limit may suffer from a disordered locality characterized by
identifications of far away points. We argue that if such defects in locality
are rare enough they will be difficult to detect.Comment: 11 pages, 4 figures, revision with extended discussion of result
Gambaran Pengetahuan dan Sikap Orang Tua Siswa Kelas I dan II Sdn 005 Bukit Kapur Dumai Tentang Karies Gigi
Caries is a demineralization of the tooth surface caused by bacteria. Parents who have a low knowledge about the prevention of dental caries, tend to pay less attention to the oral health of children that can cause dental caries.The purpose of this study to describe the knowledge and attitudes of parents about dental caries. This research was conducted in SDN 005 Bukit Kapur Dumai descriptive with cross sectional approach. Samples in this study are the parents of the students of class I and II, and with a sample size of at least 150 parents. Data were collected by interview using a questionnaire. From the results of this study, scoring on a sufficient level of knowledge (54.67%), neutral position (62.00%). Based on gender the parents who followed in this study were (64.00%) of women with an age range of 20-35 years (60.00%) also had high school (56.00%) and work as a housewife (55, 33%)
Damage-free single-mode transmission of deep-UV light in hollow-core PCF
Transmission of UV light with high beam quality and pointing stability is
desirable for many experiments in atomic, molecular and optical physics. In
particular, laser cooling and coherent manipulation of trapped ions with
transitions in the UV require stable, single-mode light delivery. Transmitting
even ~2 mW CW light at 280 nm through silica solid-core fibers has previously
been found to cause transmission degradation after just a few hours due to
optical damage. We show that photonic crystal fiber of the kagom\'e type can be
used for effectively single-mode transmission with acceptable loss and bending
sensitivity. No transmission degradation was observed even after >100 hours of
operation with 15 mW CW input power. In addition it is shown that
implementation of the fiber in a trapped ion experiment significantly increases
the coherence times of the internal state transfer due to an increase in beam
pointing stability
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