4,013 research outputs found
Coherent Microwave Control of Ultracold NaK Molecules
We demonstrate coherent microwave control of rotational and hyperfine states
of trapped, ultracold, and chemically stable NaK molecules.
Starting with all molecules in the absolute rovibrational and hyperfine ground
state, we study rotational transitions in combined magnetic and electric fields
and explain the rich hyperfine structure. Following the transfer of the entire
molecular ensemble into a single hyperfine level of the first rotationally
excited state, , we observe collisional lifetimes of more than , comparable to those in the rovibrational ground state, . Long-lived
ensembles and full quantum state control are prerequisites for the use of
ultracold molecules in quantum simulation, precision measurements and quantum
information processing.Comment: 5 pages, 4 figure
Spatially resolved pump-probe study of single-layer graphene produced by chemical vapor deposition
Carrier dynamics in single-layer graphene grown by chemical vapor deposition
(CVD) is studied using spatially and temporally resolved pump-probe
spectroscopy by measuring both differential transmission and differential
reflection. By studying the expansion of a Gaussian spatial profile of carriers
excited by a 1500-nm pump pulse with a 1761-nm probe pulse, we observe a
diffusion of hot carriers of 5500 square centimeter per second. We also observe
that the expansion of the carrier density profile decreases to a slow rate
within 1 ps, which is unexpected. Furthermore, by using an 810-nm probe pulse
we observe that both the differential transmission and reflection change signs,
but also that this sign change can be permanently removed by exposure of the
graphene to femtosecond laser pulses of relatively high fluence. This indicates
that the differential transmission and reflection at later times may not be
directly caused by carriers, but may be from some residue material from the
sample fabrication or transfer process.Comment: 9 pages, 3 figure
An encryption-decryption framework for validating single-particle imaging
We propose an encryption–decryption framework for validating diffraction intensity volumes reconstructed using single-particle imaging (SPI) with X-ray free-electron lasers (XFELs) when the ground truth volume is absent. This conceptual framework exploits each reconstructed volumes’ ability to decipher latent variables (e.g. orientations) of unseen sentinel diffraction patterns. Using this framework, we quantify novel measures of orientation disconcurrence, inconsistency, and disagreement between the decryptions by two independently reconstructed volumes. We also study how these measures can be used to define data sufficiency and its relation to spatial resolution, and the practical consequences of focusing XFEL pulses to smaller foci. This conceptual framework overcomes critical ambiguities in using Fourier Shell Correlation (FSC) as a validation measure for SPI. Finally, we show how this encryption-decryption framework naturally leads to an information-theoretic reformulation of the resolving power of XFEL-SPI, which we hope will lead to principled frameworks for experiment and instrument design
A Survey of Molecular Hydrogen in the Crab Nebula
We have carried out a near-infrared, narrow-band imaging survey of the Crab
Nebula, in the H2 2.12 micron and Br-gamma 2.17 micron lines, using the Spartan
Infrared camera on the SOAR Telescope. Over a 2.8' x 5.1' area that encompasses
about 2/3 of the full visible extent of the Crab, we detect 55 knots that emit
strongly in the H2 line. We catalog the observed properties of these knots. We
show that they are in or next to the filaments that are seen in
optical-passband emission lines. Comparison to HST [S II] and [O III] images
shows that the H2 knots are strongly associated with compact regions of
low-ionization gas. We also find evidence of many additional, fainter H2
features, both discrete knots and long streamers following gas that emits
strongly in [S II]. A pixel-by-pixel analysis shows that about 6 percent of the
Crab's projected surface area has significant H2 emission that correlates with
[S II] emission. We measured radial velocities of the [S II] lambda6716
emission lines from 47 of the cataloged knots and find that most are on the far
(receding) side of the nebula. We also detect Br-gamma emission. It is right at
the limit of our survey, and our Br-gamma filter cuts off part of the expected
velocity range. But clearly the Br-gamma emission has a quite different
morphology than the H2 knots, following the long linear filaments that are seen
in H-alpha and in [O III] optical emission lines.Comment: Accepted for publication in the ApJ
Recent strategies in resveratrol delivery systems
Resveratrol, a natural polyphenolic stilbenoid widely found in grapes and wines, displays beneficial properties such as cardio-protective, antioxidant and anti-inflammatory activities. Trans-resveratrol (RSV) is the most bioactive and more abundant stereoisomer found in nature. Despite the positive properties of RSV, there are various factors that limit its effectiveness, including low aqueous solubility, low oral bioavailability and chemical instability. During the last years, an increasing number of strategies such as nano and micro encapsulation have been developed in order to overcome these limitations and enhance the use of RSV in nutritional and pharmaceutical applications. This Review summarizes the advances and main properties of several RSV carriers and delivery systems reported during the last 5 years.Fil: Machado, Noelia Daiana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Fernández, Mariana Adela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Díaz, David Díaz. Universitat Regensburg; Alemani
Diffraction-limited imaging with monolayer 2D material-based ultrathin flat lenses.
Ultrathin flat optics allow control of light at the subwavelength scale that is unmatched by traditional refractive optics. To approach the atomically thin limit, the use of 2D materials is an attractive possibility due to their high refractive indices. However, achievement of diffraction-limited focusing and imaging is challenged by their thickness-limited spatial resolution and focusing efficiency. Here we report a universal method to transform 2D monolayers into ultrathin flat lenses. Femtosecond laser direct writing was applied to generate local scattering media inside a monolayer, which overcomes the longstanding challenge of obtaining sufficient phase or amplitude modulation in atomically thin 2D materials. We achieved highly efficient 3D focusing with subwavelength resolution and diffraction-limited imaging. The high focusing performance even allows diffraction-limited imaging at different focal positions with varying magnifications. Our work paves the way for downscaling of optical devices using 2D materials and reports an unprecedented approach for fabricating ultrathin imaging devices
Semiconductor photocatalysis to engineering deuterated N-alkyl pharmaceuticals enabled by synergistic activation of water and alkanols
Precisely controlled deuterium labeling at specific sites of N-alkyl drugs is crucial in drug-development as over 50% of the top-selling drugs contain N-alkyl groups, in which it is very challenging to selectively replace protons with deuterium atoms. With the goal of achieving controllable isotope-labeling in N-alkylated amines, we herein rationally design photocatalytic water-splitting to furnish [H] or [D] and isotope alkanol-oxidation by photoexcited electron-hole pairs on a polymeric semiconductor. The controlled installation of N-CH3, -CDH2, -CD2H, -CD3, and -13CH3 groups into pharmaceutical amines thus has been demonstrated by tuning isotopic water and methanol. More than 50 examples with a wide range of functionalities are presented, demonstrating the universal applicability and mildness of this strategy. Gram-scale production has been realized, paving the way for the practical photosynthesis of pharmaceuticals
Effect of fermented fruits on the growth performance, shedding of Enterobacteriaceae and Lactobacilli in post-weaning pigs
The aim of this study was to investigate the effect of fermented fruits (FF) on the growth performance, Enterobacteriaceae and Lactobacillus counts in faeces of the post-weaning piglets. A total of twenty-four 4 weeks old LandracexLarge WhitexDuroc with initial body weight of 6 kg were used in this study. The piglets were housed individually in metabolic cage and randomly assigned to four groups with six piglets per group. The piglets were fed on basal diet without antibiotic (AF), basal diets with antibiotic (Ab), basal diet with 10% (w/w) fermented fruit (10% FF) and basal diet with 20% (w/w) fermented fruit (20% FF). Faecal samples were taken directly from the rectum of each piglet and cultured for Enterobacteriaceae and Lactobacillus counts. In the growth performance, the piglets of Ab and 10%FF had significantly higher (p0.05) were observed between AF, Ab and 10%FF. Studies showed that the use of fermented fruits (FF) could significantly (p<0.05) reduce Enterobacteriaceae population in piglets' faeces compared to the use of normal feed (AF) and antibiotic (Ab). However, the Lactobacillus population in the faeces was increased in those piglets fed with diets added with FF
Resonant dipolar collisions of ultracold molecules induced by microwave dressing
We demonstrate microwave dressing on ultracold, fermionic
NaK ground-state molecules and observe resonant dipolar
collisions with cross sections exceeding three times the -wave unitarity
limit. The origin of these collisions is the resonant alignment of the
approaching molecules' dipoles along the intermolecular axis, which leads to
strong attraction. We explain our observations with a conceptually simple
two-state picture based on the Condon approximation. Furthermore, we perform
coupled-channels calculations that agree well with the experimentally observed
collision rates. While collisions are observed here as laser-induced loss,
microwave dressing on chemically stable molecules trapped in box potentials may
enable the creation of strongly interacting dipolar gases of molecules.Comment: 6 pages, 4 figure
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