9,430 research outputs found
Organization of Block Copolymers using NanoImprint Lithography: Comparison of Theory and Experiments
We present NanoImprint lithography experiments and modeling of thin films of
block copolymers (BCP). The NanoImprint lithography is used to align
perpendicularly lamellar phases, over distances much larger than the natural
lamellar periodicity. The modeling relies on self-consistent field calculations
done in two- and three-dimensions. We get a good agreement with the NanoImprint
lithography setups. We find that, at thermodynamical equilibrium, the ordered
BCP lamellae are much better aligned than when the films are deposited on
uniform planar surfaces
Block Copolymer at Nano-Patterned Surfaces
We present numerical calculations of lamellar phases of block copolymers at
patterned surfaces. We model symmetric di-block copolymer films forming
lamellar phases and the effect of geometrical and chemical surface patterning
on the alignment and orientation of lamellar phases. The calculations are done
within self-consistent field theory (SCFT), where the semi-implicit relaxation
scheme is used to solve the diffusion equation. Two specific set-ups, motivated
by recent experiments, are investigated. In the first, the film is placed on
top of a surface imprinted with long chemical stripes. The stripes interact
more favorably with one of the two blocks and induce a perpendicular
orientation in a large range of system parameters. However, the system is found
to be sensitive to its initial conditions, and sometimes gets trapped into a
metastable mixed state composed of domains in parallel and perpendicular
orientations. In a second set-up, we study the film structure and orientation
when it is pressed against a hard grooved mold. The mold surface prefers one of
the two components and this set-up is found to be superior for inducing a
perfect perpendicular lamellar orientation for a wide range of system
parameters
Production of xylanase and ÎČ-xylosidase from autohydrolysis liquor of corncob using two fungal strains
Agroindustrial residues are materials often rich in cellulose and hemicellulose. The use of these substrates for the microbial production of enzymes of industrial interest is mainly due to their high availability associated with their low cost. In this work, corncob (CCs) particles decomposed to soluble compounds (liquor) were incorporated in the microbial growth medium through autohydrolysis, as a strategy to increase and undervalue xylanase and
b-xylosidase production by Aspergillus terricola and Aspergillus ochraceus. The CCs autohydrolysis liquor produced at 200 C for 5, 15, 30 or 50 min was used as the sole carbon source or associated with untreated CC. The best condition for enzyme synthesis was observed with CCs submitted to 30 min of autohydrolysis. The enzymatic production with untreated CCs plus CC liquor was higher
than with birchwood xylan for both microorganisms.
A. terricola produced 750 total U of xylanase (144 h cultivation) and 30 total U of b-xylosidase (96â168 h) with 0.75% untreated CCs and 6% CCs liquor, against 650 total U of xylanase and 2 total U of b-xylosidase in xylan; A. ochraceus produced 605 total U of xylanase and 56 total U of b-xylosidase (168 h cultivation) with 1% untreated
CCs and 10% CCs liquor against 400 total U of xylanase and 38 total U of b-xylosidase in xylan. These results indicate that the treatment of agroindustrial wastes through autohydrolysis can be a viable strategy in the production of high levels of xylanolytic enzymes.This work was supported by State of Sao Paulo Research Foundation (FAPESP/Brazil), National Counsel of Technological and Scientific Development (CNPq/Brazil), National System for Research on Biodiversity (SISBIOTA-Brazil, CNPq 563260/2010-6/FAPESP 2010/52322-3), and Portuguese Foundation for Science and Technology (FCT/Portugal). Hector A. Ruiz thanks to Mexican Science and Technology Council (CONACYT, Mexico) for PhD fellowship support (CONACYT grant number: 213592/308679)
A Novel Technique to Label Cover Crop Biomass Using Stable Isotopes
Stable isotopes can be used as tracers for carbon and nitrogen pathways being a great tool to track nutrients in integrated systems. The objective of this experiment was to understand the partitioning of 15N and 13C within cover crop plants when they were labeled with stable isotopes, using chambers under field conditions. Cover crops were planted at the University of Florida, North Florida Research and Education Center-Marianna, located in Marianna, FL. Treatments were four cover crops, in which one was considered a typical cover crop system and the other three consisted of an integrated crop-livestock system with or without the inclusion of legume or different nitrogen fertilizer rates grazed every two weeks. All treatments were replicated three times in a randomized complete block design. Two chambers were built and placed in each plot to label the cover crop plants. For the 15N labeling, 15N2-labeled urea (98 atom% 15N) was applied at a rate of 0.5 kg N ha-1 only once. The target amount of 13CO2 (99 atom% 13C) was determined considering a 20% enrichment of the CO2 concentration present inside the chamberâs volume. The 13CO2 labeling was performed for 28 consecutive days. The labeling technique using chambers and stable isotopes to enrich cover crop species worked under field conditions for both, grass and legume species. Moving forward, this labeling technique can be a useful tool to track nutrient pathways, especially litter decomposition in diversified integrated crop and livestock systems under different management practices
Antiproliferative activity of flavonoids from croton Sphaerogynus baill. (euphorbiaceae)
Croton sphaerogynus is a shrub from the Atlantic Rain Forest in southeastern Brazil. A lyophilized crude EtOH extract from leaves of C. sphaerogynus, obtained by maceration at room temperature (seven days), was suspended in methanol and partitioned with hexane. The purified MeOH phase was fractionated over Sephadex LH-20 yielding five fractions (F1-F5) containing flavonoids, as characterized by HPLC-DAD and HPLC-MS analyses. The antiproliferative activity of the crude EtOH extract, MeOH and hexane phases, and fractions F1-F5 was evaluated on in vitro cell lines NCI-H460 (nonsmall cell lung), MCF-7 (breast cancer), and U251 (glioma). The MeOH phase showed activity (mean log GI(50) 0.54) higher than the hexane phase and EtOH extract (mean log GI(50) 1.13 and 1.19, resp.). F1 exhibited activity against NCI-H460 (nonsmall cell lung) (GI(50) 1.2 mu g/mL), which could be accounted for the presence of flavonoids and/or diterpenes. F4 showed moderate activity (mean log GI(50) 1.05), while F5 showed weak activity (mean log GI(50) 1.36). It is suggested that the antiproliferative activity of the crude EtOH extract and MeOH phase is accounted for a synergistic combination of flavonoids and diterpenes2015COORDENAĂĂO DE APERFEIĂOAMENTO DE PESSOAL DE NĂVEL SUPERIOR - CAPESFUNDAĂĂO DE AMPARO Ă PESQUISA DO ESTADO DE SĂO PAULO - FAPESPsem informação2012/10079-
Antiproliferative Activity Of Flavonoids From Croton Sphaerogynus Baill. (euphorbiaceae).
Croton sphaerogynus is a shrub from the Atlantic Rain Forest in southeastern Brazil. A lyophilized crude EtOH extract from leaves of C. sphaerogynus, obtained by maceration at room temperature (seven days), was suspended in methanol and partitioned with hexane. The purified MeOH phase was fractionated over Sephadex LH-20 yielding five fractions (F1-F5) containing flavonoids, as characterized by HPLC-DAD and HPLC-MS analyses. The antiproliferative activity of the crude EtOH extract, MeOH and hexane phases, and fractions F1-F5 was evaluated on in vitro cell lines NCI-H460 (nonsmall cell lung), MCF-7 (breast cancer), and U251 (glioma). The MeOH phase showed activity (mean logâGI50 0.54) higher than the hexane phase and EtOH extract (mean logâGI50 1.13 and 1.19, resp.). F1 exhibited activity against NCI-H460 (nonsmall cell lung) (GI50 1.2âÎŒg/mL), which could be accounted for the presence of flavonoids and/or diterpenes. F4 showed moderate activity (mean logâGI50 1.05), while F5 showed weak activity (mean logâGI50 1.36). It is suggested that the antiproliferative activity of the crude EtOH extract and MeOH phase is accounted for a synergistic combination of flavonoids and diterpenes.201521280
Measurement of the cross-section and charge asymmetry of bosons produced in proton-proton collisions at TeV with the ATLAS detector
This paper presents measurements of the and cross-sections and the associated charge asymmetry as a
function of the absolute pseudorapidity of the decay muon. The data were
collected in proton--proton collisions at a centre-of-mass energy of 8 TeV with
the ATLAS experiment at the LHC and correspond to a total integrated luminosity
of 20.2~\mbox{fb^{-1}}. The precision of the cross-section measurements
varies between 0.8% to 1.5% as a function of the pseudorapidity, excluding the
1.9% uncertainty on the integrated luminosity. The charge asymmetry is measured
with an uncertainty between 0.002 and 0.003. The results are compared with
predictions based on next-to-next-to-leading-order calculations with various
parton distribution functions and have the sensitivity to discriminate between
them.Comment: 38 pages in total, author list starting page 22, 5 figures, 4 tables,
submitted to EPJC. All figures including auxiliary figures are available at
https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/STDM-2017-13
Search for chargino-neutralino production with mass splittings near the electroweak scale in three-lepton final states in âs=13âTeV pp collisions with the ATLAS detector
A search for supersymmetry through the pair production of electroweakinos with mass splittings near the electroweak scale and decaying via on-shell W and Z bosons is presented for a three-lepton final state. The analyzed proton-proton collision data taken at a center-of-mass energy of âs=13ââTeV were collected between 2015 and 2018 by the ATLAS experiment at the Large Hadron Collider, corresponding to an integrated luminosity of 139ââfbâ1. A search, emulating the recursive jigsaw reconstruction technique with easily reproducible laboratory-frame variables, is performed. The two excesses observed in the 2015â2016 data recursive jigsaw analysis in the low-mass three-lepton phase space are reproduced. Results with the full data set are in agreement with the Standard Model expectations. They are interpreted to set exclusion limits at the 95% confidence level on simplified models of chargino-neutralino pair production for masses up to 345 GeV
Measurement of the ratio of branching fractions BR(B0 -> K*0 gamma)/BR(Bs0 -> phi gamma)
The ratio of branching fractions of the radiative B decays B0 -> K*0 gamma
and Bs0 -> phi gamma has been measured using 0.37 fb-1 of pp collisions at a
centre of mass energy of sqrt(s) = 7 TeV, collected by the LHCb experiment. The
value obtained is BR(B0 -> K*0 gamma)/BR(Bs0 -> phi gamma) = 1.12 +/- 0.08
^{+0.06}_{-0.04} ^{+0.09}_{-0.08}, where the first uncertainty is statistical,
the second systematic and the third is associated to the ratio of fragmentation
fractions fs/fd. Using the world average for BR(B0 -> K*0 gamma) = (4.33 +/-
0.15) x 10^{-5}, the branching fraction BR(Bs0 -> phi gamma) is measured to be
(3.9 +/- 0.5) x 10^{-5}, which is the most precise measurement to date.Comment: 15 pages, 1 figure, 2 table
Search for CP violation in decays
A model-independent search for direct CP violation in the Cabibbo suppressed
decay in a sample of approximately 370,000 decays is
carried out. The data were collected by the LHCb experiment in 2010 and
correspond to an integrated luminosity of 35 pb. The normalized Dalitz
plot distributions for and are compared using four different
binning schemes that are sensitive to different manifestations of CP violation.
No evidence for CP asymmetry is found.Comment: 13 pages, 8 figures, submitted to Phys. Rev.
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