1,042 research outputs found
Evaluation of nano-frictional and mechanical properties of a novel Langmuir-Blodgett monolayer/self-assembly monolayer composite structure
A novel stearic acid (SA)/3-aminopropyltrethoxysilane (APS) composite
structure was fabricated using the combined method of the Langmuir-Blodgett
technique and self-assembly monolayer (SAM) technique. Its frictional, adhesive
properties and interface contact types between the atomic force microscope tip
and the samples were evaluated based on Amonton's laws and the general
Carpick's transition equation, respectively. The results showed that the
tip-sample contacts corresponded to the
Johnson-Kendall-Robert/Derjaguin-Muller-Toporov (DMT) transition model for
SiO2, APS-SAMs, and the unheated SA-APS composite structure, and for the heated
SA-APS bilayer to the DMT model. Frictional forces for the four samples were
linearly dependent on external loads at higher loads, and at lower loads they
were significantly affected by adhesive forces. Frictional and scratching tests
showed that the heated SA-APS composite structure exhibited the best
lubricating properties and adhesion resistance ability, and its wear resistance
capacity was greatly improved due to the binding-mode conversion from hydrogen
bonds to covalent bonds. Thus, this kind of composite bilayer might be
promising for applications in the lubrication of nano/microelectromechanical
systems. I.Comment: 8 pages, 8 figure
Model-Independent Determination of and using Time-Delay Galaxy Lenses and Gamma-Ray Bursts
Combining the `time-delay distance' () measurements from galaxy
lenses and other distance indicators provides model-independent determinations
of the Hubble constant () and spatial curvature (), only
based on the validity of the Friedmann-Lema\^itre-Robertson-Walker (FLRW)
metric and geometrical optics. To take the full merit of combining measurements in constraining , we use gamma-ray burst (GRB) distances
to extend the redshift coverage of lensing systems much higher than that of
Type Ia Supernovae (SNe Ia) and even higher than quasars, whilst the general
cosmography with a curvature component is implemented for the GRB distance
parametrizations. Combining Lensing+GRB yields ~km
sMpc and (1). A
flat-universe prior gives slightly an improved ~km
sMpc. When combining Lensing+GRB+SN Ia, the error bar falls by 25\%, whereas is not improved due to the
degeneracy between SN Ia absolute magnitude, , and along with the
mismatch between the SN Ia and GRB Hubble diagrams at . Future
increment of GRB observations can help to moderately eliminate the
degeneracy in SN Ia distances and ameliorate the restrictions on cosmographic
parameters along with when combining Lensing+SN Ia+GRB. We
conclude that there is no evidence of significant deviation from a (an) flat
(accelerating) universe and is currently determined at 3\% precision. The
measurements show great potential to arbitrate the tension between the
local distance ladder and cosmic microwave background measurements and provide
a relevant consistency test of the FLRW metric.Comment: Accepted for publication in MNRA
Effect of Langmuir monolayer of bovine serum albumin protein on the morphology of calcium carbonate
Bovine serum albumin (BSA) Langmuir monolayer, as a model of
biomineralization-associated proteins, was used to study its effect on
regulated biomineralization of calcium carbonate. The effects of the BSA
Langmuir monolayer and the concentration of the subphase solution on the
nucleation and growth processes and morphology of the calcium carbonate crystal
were investigated. The morphology and polymorphic phase of the resulting
calcium carbonate crystals were characterized by scanning electron microscopy
(SEM) and X-ray diffraction analysis (XRD). Moreover, the interaction
mechanisms of the subphase solution with the BSA Langmuir monolayer were
discussed. It was found that BSA Langmuir monolayer could be used as a template
to successfully manipulate the polymorphic phase and crystal morphology of
calcium carbonate and had obvious influence on the oriented crystallization and
growth. The final morphology or aggregation mode of the calcite crystal was
closely dependent on the concentration of calcium bicarbonate solution. It is
expected that this research would help to better understand the mechanism of
biomineralization by revealing the interactions between protein matrices and
crystallization of calcium carbonate crystal.Comment: 4 pages, 4 figure
Anticancer activity of an extract from needles and twigs of Taxus cuspidata and its synergistic effect as a cocktail with 5-fluorouracil
<p>Abstract</p> <p>Background</p> <p>Botanical medicines are increasingly combined with chemotherapeutics as anticancer drug cocktails. This study aimed to assess the chemotherapeutic potential of an extract of <it>Taxus cuspidata </it>(<it>TC</it>) needles and twigs produced by artificial cuttage and its co-effects as a cocktail with 5-fluorouracil (5-FU).</p> <p>Methods</p> <p>Components of <it>TC </it>extract were identified by HPLC fingerprinting. Cytotoxicity analysis was performed by MTT assay or ATP assay. Apoptosis studies were analyzed by H & E, PI, TUNEL staining, as well as Annexin V/PI assay. Cell cycle analysis was performed by flow cytometry. 5-FU concentrations in rat plasma were determined by HPLC and the pharmacokinetic parameters were estimated using 3p87 software. Synergistic efficacy was subjected to median effect analysis with the mutually nonexclusive model using Calcusyn1 software. The significance of differences between values was estimated by using a one-way ANOVA.</p> <p>Results</p> <p><it>TC </it>extract reached inhibition rates of 70-90% in different human cancer cell lines (HL-60, BGC-823, KB, Bel-7402, and HeLa) but only 5-7% in normal mouse T/B lymphocytes, demonstrating the broad-spectrum anticancer activity and low toxicity to normal cells of <it>TC </it>extract <it>in vitro</it>. <it>TC </it>extract inhibited cancer cell growth by inducing apoptosis and G<sub>2</sub>/M cell cycle arrest. Most interestingly, <it>TC </it>extract and 5-FU, combined as a cocktail, synergistically inhibited the growth of cancer cells <it>in vitro</it>, with Combination Index values (CI) ranging from 0.90 to 0.26 at different effect levels from IC50 to IC90 in MCF-7 cells, CI ranging from 0.93 to 0.13 for IC40 to IC90 in PC-3M-1E8 cells, and CI < 1 in A549 cells. In addition, the cocktail had lower cytotoxicity in normal human cell (HEL) than 5-FU used alone. Furthermore, <it>TC </it>extract did not affect the pharmacokinetics of 5-FU in rats.</p> <p>Conclusions</p> <p>The combinational use of the <it>TC </it>extract with 5-FU displays strong cytotoxic synergy in cancer cells and low cytotoxicity in normal cells. These findings suggest that this cocktail may have a potential role in cancer treatment.</p
Search for new phenomena in final states with an energetic jet and large missing transverse momentum in pp collisions at √ s = 8 TeV with the ATLAS detector
Results of a search for new phenomena in final states with an energetic jet and large missing transverse momentum are reported. The search uses 20.3 fb−1 of √ s = 8 TeV data collected in 2012 with the ATLAS detector at the LHC. Events are required to have at least one jet with pT > 120 GeV and no leptons. Nine signal regions are considered with increasing missing transverse momentum requirements between Emiss T > 150 GeV and Emiss T > 700 GeV. Good agreement is observed between the number of events in data and Standard Model expectations. The results are translated into exclusion limits on models with either large extra spatial dimensions, pair production of weakly interacting dark matter candidates, or production of very light gravitinos in a gauge-mediated supersymmetric model. In addition, limits on the production of an invisibly decaying Higgs-like boson leading to similar topologies in the final state are presente
Graphene-Based Nanocomposites for Energy Storage
Since the first report of using micromechanical cleavage method to produce graphene sheets in 2004, graphene/graphene-based nanocomposites have attracted wide attention both for fundamental aspects as well as applications in advanced energy storage and conversion systems. In comparison to other materials, graphene-based nanostructured materials have unique 2D structure, high electronic mobility, exceptional electronic and thermal conductivities, excellent optical transmittance, good mechanical strength, and ultrahigh surface area. Therefore, they are considered as attractive materials for hydrogen (H2) storage and high-performance electrochemical energy storage devices, such as supercapacitors, rechargeable lithium (Li)-ion batteries, Li–sulfur batteries, Li–air batteries, sodium (Na)-ion batteries, Na–air batteries, zinc (Zn)–air batteries, and vanadium redox flow batteries (VRFB), etc., as they can improve the efficiency, capacity, gravimetric energy/power densities, and cycle life of these energy storage devices. In this article, recent progress reported on the synthesis and fabrication of graphene nanocomposite materials for applications in these aforementioned various energy storage systems is reviewed. Importantly, the prospects and future challenges in both scalable manufacturing and more energy storage-related applications are discussed
Measurement of the cross section of at center-of-mass energies between 3.510 and 4.843 GeV
Using collision data corresponding to a total integrated luminosity
of 12.9 collected with the BESIII detector at the BEPCII collider,
the exclusive Born cross sections and the effective form factors of the
reaction are measured via the single
baryon-tag method at 23 center-of-mass energies between 3.510 and 4.843 GeV.
Evidence for the decay is observed
with a significance of 4.5 by analyzing the measured cross sections
together with earlier BESIII results. For the other charmonium(-like) states
, , , , , and ,
no significant signal of their decay to is found. For these
states, upper limits of the products of the branching fraction and the
electronic partial width at the 90% confidence level are provided.Comment: 18 pages, 10 pages, 4 table
Amplitude analysis and branching fraction measurement of the decay
Using 2.93 of collision data collected with the
BESIII detector at the center-of-mass energy 3.773\,GeV, we perform the first
amplitude analysis of the decay and determine the
relative magnitudes and phases of different intermediate processes. The
absolute branching fraction of is measured to be
. The dominant intermediate
processes are and , with branching fractions of and , respectively
A coupled-channel analysis of the lineshape with BESIII data
We perform a study of the lineshape using the data samples of
, and collected with the BESIII detector. The effects of the coupled-channels
and the off-shell are included in the parameterization of the
lineshape. The lineshape mass parameter is obtained to be MeV. Two poles are found on the first and second Riemann
sheets corresponding to the branch cut. The pole location on
the first sheet is much closer to the threshold than the
other, and is determined to be MeV above the
threshold with an imaginary part
MeV
Measurement of the cross sections from 2.000 to 3.080 GeV
Based on collision data collected at center-of-mass energies
from 2.000 to 3.080 GeV by the BESIII detector at the BEPCII collider, a
partial wave analysis is performed for the process . The results allow the Born cross sections of the process
, as well as its subprocesses
and to be
measured. The Born cross sections for are consistent with previous measurements by BaBar and SND,
but with substantially improved precision. The Born cross section lineshape of
the process is consistent with a vector
meson state around 2.2 GeV with a statistical significance of 3.2. A
Breit-Wigner fit determines its mass as
and its width as
, where the first uncertainties are
statistical and the second ones are systematic, respectively
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