Spatial Multiplexing of Squeezed Light by Coherence Diffusion.

Spatially splitting nonclassical light beams is in principle prohibited due to noise contamination during beam splitting. We propose a platform based on thermal motion of atoms to realize spatial multiplexing of squeezed light. Light channels of separate spatial modes in an antirelaxation coated vapor cell share the same long-lived atomic coherence jointly created by all channels through the coherent diffusion of atoms, which in turn enhances the individual channel's nonlinear process responsible for light squeezing. Consequently, it behaves as squeezed light in one optical channel transferring to other distant channels even with laser powers below the threshold for squeezed light generation. An array of squeezed light beams is created with low laser power ∼ milliwatt. This approach holds great promise for applications in a multinode quantum network and quantum enhanced technologies such as quantum imaging and sensing.

Copper-dipyridylphosphine-catalyzed hydrosilylation: enantioselective synthesis of aryl- and heteroaryl cycloalkyl alcohols.

The non-precious metal copper-catalyzed enantioselective hydrosilylation of a vast array of aryl cycloalkyl ketones with different ring sizes was studied systematically for the first time (up to 99% enantiomeric excess). The results demonstrated that the steric size of cycloalkyl groups has a significant influence on the reaction outcomes. The first stereoselective formation of a selection of cyclohexyl heteroaryl alcohols of up to 97% enantiopurity was realized as well. Dramatic temperature effects on both the enantiopurity and the absolute configuration of the alcohol products were observed in the reduction of some cyclohexyl pyridyl ketones.

Machine learning assisted vector atomic magnetometry.

Multiparameter sensing such as vector magnetometry often involves complex setups due to various external fields needed in explicitly connecting one measured signal to one parameter. Here, we propose a paradigm of indirect encoding for vector atomic magnetometry based on machine learning. We encode the three-dimensional magnetic-field information in the set of four simultaneously acquired signals associated with the optical rotation of a laser beam traversing the atomic sample. The map between the recorded signals and the vectorial field information is established through a pre-trained deep neural network. We demonstrate experimentally a single-shot all optical vector atomic magnetometer, with a simple scalar-magnetometer design employing only one elliptically-polarized laser beam and no additional coils. Magnetic field amplitude sensitivities of about 100 [Formula: see text] and angular sensitivities of about [Formula: see text] (for a magnetic field of around 140 nT) are derived from the neural network. Our approach can reduce the complexity of the architecture of vector magnetometers, and may shed light on the general design of multiparameter sensing.

Cu(II)-catalyzed asymmetric hydrosilylation of diaryl- and aryl heteroaryl ketones: application in the enantioselective synthesis of orphenadrine and neobenodine.

With certain amounts of sodium tert-butoxide and tert-butanol as additives, catalytic amounts of an inexpensive and easy-to-handle copper source Cu(OAc)(2)⋅H(2)O, a commercially available and air-stable non-racemic dipyridylphosphine ligand, as well as the stoichiometric desirable hydride donor polymethylhydrosiloxane (PMHS), formed a versatile in situ catalyst system for the enantioselective reduction of a broad spectrum of prochiral diaryl and aryl heteroarylketones in air, in high yields and with good to excellent enantioselectivities (up to 96 %). In particular, the practical viability of this process was evinced by its successful applications in the asymmetric synthesis of optically enriched potent antihistaminic drugs orphenadrine and neobenodine.

Copper(II)-catalyzed hydrosilylation of ketones using chiral dipyridylphosphane ligands: highly enantioselective synthesis of valuable alcohols.

In the presence of PhSiH(3) as the reductant, the combination of enantiomeric dipyridylphosphane ligands and Cu(OAc)(2)·H(2)O, which is an easy-to-handle and inexpensive copper salt, led to a remarkably practical and versatile chiral catalyst system. The stereoselective formation of a selection of synthetically interesting ß-, γ- or δ-halo alcohols bearing high degrees of enantiopurity (up to 99.9% enantiomeric excess (ee)) was realized with a substrate-to-ligand molar ratio (S/L) of up to 10,000. The present protocol also allowed the hydrosilylation of a diverse spectrum of alkyl aryl ketones with excellent enantioselectivities (up to 98% ee) and exceedingly high turn-over rates (up to 50,000 S/L molar ratio in 50 min reaction time) in air, under very mild conditions, which offers great opportunities for the preparation of various physiologically active targets. The synthetic utility of the chiral products obtained was highlighted by the efficient conversion of optically enriched ß-halo alcohols into the corresponding styrene oxide, ß-amino alcohol, and ß-azido alcohol, respectively.

Cobalt(II)-catalyzed asymmetric hydrosilylation of simple ketones using dipyridylphosphine ligands in air.

In the presence of PhSiH(3) as the hydride donor, catalytic amounts of non-racemic dipyridylphosphine and an easy-to-handle cobalt salt Co(OAc)(2)·4H(2)O formed in situ an effective catalyst system for the asymmetric reduction of a diverse range of aryl alkyl ketones with moderate-to-excellent enantioselectivities (up to 96% ee). This approach tolerated the handling of both catalyst and reactants under air without special precautions.

Exploration of O3-precursor relationship and observation-oriented O3 control strategies in a non-provincial capital city, southwestern China.

To investigate photochemical ozone (O3) formation and provide localized control strategies, an intensive sampling of O3 and its precursors (i.e. volatile organic compounds (VOCs) and nitrogen oxides (NOx = NO + NO2)) were conducted at an urban site in Leshan, Sichuan province during 4-13 August 2019. The mixing ratios of O3, total VOCs (TVOCs) and NOx were 40.0 ± 5.3, 22.5 ± 2.6 and 14.6 ± 3.8 ppbv, respectively (±95% confidence intervals). O3 and its precursors existed a well negative correlation, indicating intensive local O3 formation. To further explore the O3-precursors relationship and observation-oriented O3 control strategies, a photochemical box model coupled with master chemical mechanism (PBM-MCM) was adapted. The relative incremental reactivity (RIR) calculated by model results showed that Leshan was in the VOCs-limited and O3 production was most sensitive to alkenes. Moreover, O3 isopleth diagram was drawn using the PBM-MCM simulation results and seven reduction scenarios were evaluated in Leshan. The reduction ratio of VOCs/NOx on 3:1 was proposed to be the best solution, which can be achieved effective reduction on local O3 formation. At last, since VOCs were the key precursors of O3 in Leshan, VOC sources and their potential contributions to O3 formation were investigated by using the positive matrix factorization (PMF) model. Seven sources were identified, and traffic related emissions (including vehicle exhaust and gasoline evaporation, 29.9%) and fixed combustion (27.7%) had the large contribution to ambient VOCs. Among anthropogenic sources, fixed combustion and solvent usage in painting were the large contributors to O3 formation, accounting for 30.9% and 18.3%, respectively, which should have high priorities on source reduction. This study provides scientific advices for future O3 pollution control strategies in Leshan, which can be extended to other cities.

Bioremediation of bacteria pollution using the marine sponge Hymeniacidon perlevis in the intensive mariculture water system of turbot Scophthalmus maximus.

Sessile filter-feeding marine sponges (Porifera) have been reported to possess high efficiency in removing bacteria pollution from natural or aquaculture seawater. However, no investigation has been carried out thus far in a true mariculture farm water system. Therefore this study sought to investigate the ability of the marine sponge Hymeniacidon perlevis to bioremediate the bacteria pollution in the intensive aquaculture water system of turbot Scophthalmus maximus. Sponge specimens were hung in fish culture effluent at different temperature to investigate the optimal temperature condition for bacteria removal by H. perlevis. Turbots S. maximus were co-cultured with sponge H. perlevis in 1.5 m(3) of water system at 15-18 degrees C for 6 weeks to control the growth of bacteria. It was found that H. perlevis was able to remove pathogenic bacteria efficiently at 10-20 degrees C, with a maximal removal of 71.4-78.8% of fecal coliform, 73.9-98.7% of pathogenic vibrio, and 75.0-83.7% of total culturable bacteria from fish-culture effluent at 15 degrees C; H. perlevis continuously showed good bioremediation of bacteria pollution in the S. maximus culture water system, achieving removal of 60.0-90.2% of fecal coliform, 37.6-81.6% of pathogenic vibrio, and 45.1-83.9% of total culturable bacteria. The results demonstrate that H. perlevis is an effective bioremediator of bacteria pollution in the turbot S. maximus culture farm water system.

Application of copper(II)-dipyridylphosphine catalyst in the asymmetric hydrosilylation of simple ketones in air.

Ask a copper: A copper(II) salt/chiral dipyridylphosphine/PhSiH(3) system (see scheme) acts as a very effective and practical catalyst for the asymmetric reduction of heteroaromatic and other types of ketones in air with good-to-excellent enantioselectivities (up to 94%), giving many chiral alcohols that are intermediates for physiologically active compounds. Remarkable temperature effects were observed for some heteroaromatic ketones.

Solid fuel combustion as a major contributor of polycyclic aromatic hydrocarbons in rural China: Evidence from emission inventory and congener profiles in tree bark.

Polycyclic aromatic hydrocarbons (PAHs) remain a focal concern of the air pollution in China. To discriminate the sources of airborne PAHs in Chinese rural regions, a national-scale tree bark sampling campaign and emission inventory estimation were conducted. The concentrations of the sum of 16 U.S. EPA priority PAHs in rural bark ranged from 6.30 to 3803 ng/g, with the dominance of 3- and 4-ring PAHs. Bark residual PAH concentration correlated significantly with emission flux rate, bark lipid content, ambient PM2.5, precipitation and sampling location. Based on the information of emission data, bark PAH congener profiles, principal component analysis, diagnostic ratios and compound-specific isotope analysis, solid fuel combustion was identified as the major source and could explain 40.3%-46.4% of bark PAH residues in rural China. The δ13C values of most individual PAHs were more negative at sites with lower longitude and latitude, suggesting a greater contribution of biomass combustion to PAH residues. Our results suggest the importance of regulating solid fuel combustion to significantly improve the air quality in China, and bark samples can provide a wealth of information on effectively monitoring and controlling the sources of PAH emission in rural China.