5,605,038 research outputs found
Forced assembly by multilayer coextrusion to create oriented graphene reinforced polymer nanocomposites
A potential advantage of platelet-like nanofillers as nanocomposite reinforcements is the possibility of achieving two-dimensional stiffening through planar orientation of the platelets. The ability to achieve improved properties through in-plane orientation of the platelets is a challenge and, here, we present the first results of using forced assembly to orient graphene nanoplatelets in poly(methyl methacrylate)/ polystyrene (PMMA/PS) and PMMA/PMMA multilayer films produced through multilayer coextrusion. The films exhibited a multilayer structure made of alternating layers of polymer and polymer containing graphene as evidenced by electron microscopy. Significant single layer reinforcement of 118% at a concentration of 2 wt % graphene was achieveddhigher than previously reported reinforcement for randomly dispersed graphene. The large reinforcement is attributed to the planar orientation of the graphene in the individual polymer layers. Anisotropy of the stiffening was also observed and attributed to imperfect planar orientation of the graphene lateral to the extrusion flow
First principles calculation of lithium-phosphorus co-doped diamond
We calculate the density of states (DOS) and the Mulliken population of the
diamond and the co-doped diamonds with different concentrations of lithium (Li)
and phosphorus (P) by the method of the density functional theory, and analyze
the bonding situations of the Li-P co-doped diamond thin films and the impacts
of the Li-P co-doping on the diamond conductivities. The results show that the
Li-P atoms can promote the split of the diamond energy band near the Fermi
level, and improve the electron conductivities of the Li-P co-doped diamond
thin films, or even make the Li-P co-doped diamond from semiconductor to
conductor. The effect of Li-P co-doping concentration on the orbital charge
distributions, bond lengths and bond populations is analyzed. The Li atom may
promote the split of the energy band near the Fermi level as well as may
favorably regulate the diamond lattice distortion and expansion caused by the P
atom.Comment: 14 pages, 11 figure
Linking structure and dynamics in reactions with Borromean nuclei: the LiLi case
One-neutron removal reactions induced by two-neutron Borromean
nuclei are studied within a Transfer-to-the-Continuum (TC) reaction framework,
which incorporates the three-body character of the incident nucleus. The
relative energy distribution of the residual unbound two-body subsystem, which
is assumed to retain information on the structure of the original three-body
projectile, is computed by evaluating the transition amplitude for different
neutron-core final states in the continuum. These transition amplitudes depend
on the overlaps between the original three-body ground-state wave function and
the two-body continuum states populated in the reaction, thus ensuring a
consistent description of the incident and final nuclei. By comparing different
Li three-body models, it is found that the LiLi
relative energy spectrum is very sensitive to the position of the and
states in Li and to the partial wave content of these
configurations within the Li ground-state wave function. The possible
presence of a low-lying resonance is discussed. The coupling of the
single particle configurations with the non-zero spin of the Li core,
which produces a spin-spin splitting of the states, is also studied. Among the
considered models, the best agreement with the available data is obtained with
a Li model that incorporates the actual spin of the core and contains
31\% of -wave content in the -Li subsystem, in accord
with our previous findings for the Li(p,d)Li transfer reaction,
and a near-threshold virtual state.Comment: 7 pages, 4 figures, submitted to PL
Non-Clinical Benefits of Evidence - Based Veterinary Medicine
<div><strong>Clinical bottom line</strong></div><ul><li>There are few studies addressing business benefits of EBVM.</li><li>While the need for a wider adoption of EBVM has been highlighted and linked to commercial benefits, further empirical studies are needed to identify and quantify such linkages.</li></ul><p><br /> <img src="https://www.veterinaryevidence.org/rcvskmod/icons/oa-icon.jpg" alt="Open Access" /> <img src="https://www.veterinaryevidence.org/rcvskmod/icons/pr-icon.jpg" alt="Peer Reviewed" /></p
Long-term in situ observations on typhoon-triggered turbidity currents in the deep sea
This work is supported by the National Science Foundation of China (grants 91528304, 41576005, and 41530964). We thank J. Li, X. Lyu, P. Li, K. Duan, J. Ronan, Y. Wang, P. Ma, and Y. Li for cruise assistance; G. de Lange and J. Hinojosa for editing an early version of manuscript; and E. Pope and two anonymous reviewers for their reviews.Peer reviewedPublisher PD
Efficient prime counting and the Chebyshev primes
The function \epsilon(x)=\mbox{li}(x)-\pi(x) is known to be positive up to
the (very large) Skewes' number. Besides, according to Robin's work, the
functions \epsilon_{\theta}(x)=\mbox{li}[\theta(x)]-\pi(x) and
\epsilon_{\psi}(x)=\mbox{li}[\psi(x)]-\pi(x) are positive if and only if
Riemann hypothesis (RH) holds (the first and the second Chebyshev function are
and ,
respectively, \mbox{li}(x) is the logarithmic integral, and
are the M\"obius and the Von Mangoldt functions). Negative jumps
in the above functions , and
may potentially occur only at (the set of primes). One
denotes j_p=\mbox{li}(p)-\mbox{li}(p-1) and one investigates the jumps ,
and . In particular, , and
for . Besides, for any odd p \in
\mathcal{\mbox{Ch}}, an infinite set of so-called {\it Chebyshev primes } with
partial list . We establish a few properties of the set
\mathcal{\mbox{Ch}}, give accurate approximations of the jump
and relate the derivation of \mbox{Ch} to the explicit Mangoldt formula for
. In the context of RH, we introduce the so-called {\it Riemann
primes} as champions of the function (or of the function
). Finally, we find a {\it good} prime counting function
S_N(x)=\sum_{n=1}^N \frac{\mu(n)}{n}\mbox{li}[\psi(x)^{1/n}], that is found
to be much better than the standard Riemann prime counting function.Comment: 15 pages section 2.2 added, new sequences added, Fig. 2 and 3 are ne
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