Compact laser modulation system for a transportable atomic gravimeter.

Nowadays, atom-based quantum sensors are leaving the laboratory towards field applications requiring compact and robust laser systems. Here we describe the realization of a compact laser system for atomic gravimetry. Starting with a single diode laser operating at 780 nm and adding only one fiber electro-optical modulator, one acousto-optical modulator and one laser amplifier we produce laser beams at all the frequencies required for a Rb-87 atomic gravimeter. Furthermore, we demonstrate that an atomic fountain configuration can also be implemented with our laser system. The modulated system reported here represents a substantial advance in the simplification of the laser source for transportable atom-based quantum sensors that can be adapted to other sensors such as atomic clocks, accelerometers, gyroscopes or magnetometers with minor modifications.

Accurate temperature measurement of cold atoms in cesium fountain clocks.

We introduce a new approach to determine if a cloud of cold atoms has or not a unique, well-defined temperature. In the first case, the temperature can be determined using the width of the velocity distribution. However, the temperature in a cloud of cold atoms may not be well-defined if the velocity distribution does not turn out to be Gaussian. In this case, the width of the velocity distribution cannot be associated to a unique temperature, and additional considerations exposed here should be followed to measure the temperatures of two groups of atoms forming the whole cloud. Also an uncertainty evaluation is presented.

Chemical composition of industrially and laboratory processed Cyperus esculentus rhizomes.

We report here the results of the study of the chemical composition of Cyperus esculentus rhizomes. Ethanolic extracts have been separated by column chromatography and analyzed by magnetic resonance spectroscopy and mass spectrometry. Quercetin, stigmasterol, and linoleic and oleic acid glycerol esters, together with 4-chlorobutyl oleate, oleamide, myricetin, tyramine and N-feruloyltyramine, found for the first time in Cyperus esculentus rhizomes, have been isolated and quantified in the extracts. Alkaloids have not been detected, and the presence of flavonoids and sterols is moderate.

Impact of evolving greenhouse gas forcing on the warming signal in regional climate model experiments.

Variations in the atmospheric concentrations of greenhouse gases (GHG) may not be included as external forcing when running regional climate models (RCMs); at least, this is a non-regulated, non-documented practice. Here we investigate the so far unexplored impact of considering the rising evolution of the CO2, CH4, and N2O atmospheric concentrations on near-surface air temperature (TAS) trends, for both the recent past and the near future, as simulated by a state-of-the-art RCM over Europe. The results show that the TAS trends are significantly affected by 1-2 K century-1, which under 1.5 °C global warming translates into a non-negligible impact of up to 1 K in the regional projections of TAS, similarly affecting projections for maximum and minimum temperatures. In some cases, these differences involve a doubling signal, laying further claim to careful reconsideration of the RCM setups with regard to the inclusion of GHG concentrations as an evolving external forcing which, for the sake of research reproducibility and reliability, should be clearly documented in the literature.

Inclusion of silver nanoparticles for improving regenerated cellulose membrane performance and reduction of biofouling.

The preparation of silver nanoparticles (AgNPs) and their incorporation into the structure of a regenerated cellulose membrane by dip coating is presented. Morphological characterization of the AgNPs (average diameter of 20±2nm) was carried out by SEM/TEM, while elastic, electrical and antimicrobial properties of the hybrid membrane were also analyzed. The presence of silver nanoparticles in the membrane seems to increases its rigidity and its chemical stability against oxidation, but it only induces small changes in the transport parameters. As expected, AgNPs provide antimicrobial properties to the membrane and consequently the reduction of biofouling without affecting significantly other characteristic parameters, opening the application of the modified membrane to wastewaters treatment.

Synthesis of vinyl-terminated Au nanoprisms and nanooctahedra mediated by 3-butenoic acid: direct Au@pNIPAM fabrication with improved SERS capabilities.

Here we describe the first seedless synthesis of vinyl-terminated Au nanotriangular prisms (AuNTPs) and nanooctahedra (AuNOC) in aqueous media. This synthesis is performed by chemical reduction of chloroauric acid (HAuCl4) with 3-butenoic acid (3BA) in the presence of benzyldimethylammonium chloride (BDAC). The principal novelties of the presented method are the use of a mixture of 3BA and BDAC, the synthesis of gold prisms and octahedra with controllable size, and the presence of terminal double bonds on the metal surface. Initially this method produces a mixture of triangular gold nanoprisms and octahedra; however, both morphologies are successfully separated by surfactant micelle induced depletion interaction, reaching percentages up to ∼90%. Moreover, the alkene moieties present on the gold surface are exploited for the fabrication of hybrid core@shell particles. Gold octahedra and triangular prisms are easily encapsulated by free radical polymerization of N-isopropylacrylamide (NIPAM). Finally, in order to obtain a gold core with the most number of tips, AuNTP@pNIPAM microgels were subjected to gold core overgrowth, thus resulting in star-shaped nanoparticles (AuSTs@pNIPAM). We use 4-amino-benzenethiol as the model analyte for SERS investigations. As expected, gold cores with tips and high curvature sites produced the highest plasmonic responses.

Direct determination of alkaloid contents in Fumaria species by GC-MS.

The isoquinoline alkaloids protopine, cryptopine, sinactine, stylopine, bicuculline, adlumine, parfumine, fumariline, fumarophycine, fumaritine, dihydrofumariline, parfumidine and dihydrosanguinarine have been determined and identified by gas chromatography-mass spectrometry in Fumaria agraria, F. bastardii, F. capreolata, F. sepium, F. densiflora, F. faurei, F. officinalis subsp. officinalis, F. parviflora, F. petteri subsp. calcarata and F. macrosepala. The chemotaxonomic significance of the results is discussed.