The contamination of freshwater with microplastics (MPs) has been established globally. While the analysis of MPs has predominantly involved spectroscopic methods for revealing particle numbers, the potential of employing spectroscopy for mass estimation has been underutilized. Consequently, there is a need to enhance our understanding of the mass loads of MPs and ensure the complementarity and comparability of various techniques for accurate quantification. This study presents the first comparative results on urban water samples using micro Fourier-transform infrared (μ-FTIR) imaging and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) to identify and quantify MPs in both particle numbers and mass concentration. Two sampling campaigns in summer and winter were conducted at 11 locations within the Amsterdam canal network. An advanced in-situ volume-reducing sampling pump was employed to collect MPs from the surface water within the size fraction of 10-300 μm. The analysis revealed MP concentrations within the range of 16-107 MP/m, estimated to be 2.0-789 μg/m by μ-FTIR imaging and 8.5-754 μg/m by Py-GC-MS. The results of the two analysis techniques showed good comparability in terms of the general trends of MP abundances, with variations in polymer compositions due to the inherent inter-methodological differences. Elevated MP concentrations were observed in the city center compared to the suburban areas. In addition, seasonal differences in MP abundances were noted at the locations with high human activity.
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http://dx.doi.org/10.1016/j.envpol.2024.124088 | DOI Listing |
Phys Rev Lett
December 2024
National University of Singapore, Department of Physics, Singapore 117551.
We uncover emergent universality arising in the equilibration dynamics of multimode continuous-variable systems. Specifically, we study the ensemble of pure states supported on a small subsystem of a few modes, generated by Gaussian measurements on the remaining modes of a globally pure bosonic Gaussian state. We find that beginning from highly entangled, complex global states, such as random Gaussian states and product squeezed states coupled via a deep array of linear optical elements, the induced ensemble attains a universal form, independent of the choice of measurement basis: it is composed of unsqueezed coherent states whose displacements are distributed normally and isotropically, with variance depending on only the particle-number density of the system.
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December 2024
Univ Coimbra, Faculdade de Ciências e Tecnologia da Universidade de Coimbra and CFisUC, Rua Larga, 3004-516 Coimbra, Portugal.
The search for primordial black holes (PBHs) with masses M≪M_{⊙} is motivated by natural early-Universe production mechanisms and that PBHs can be dark matter. For M≲10^{14} kg, the PBH density is constrained by null searches for their expected Hawking emission (HE), the characteristics of which are, however, sensitive to new states beyond the standard model. If there exists a large number of spin-0 particles in nature, PBHs can, through HE, develop and maintain non-negligible spins, modifying the visible HE.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Ens de Lyon, Université Lyon, CNRS, Laboratoire de Physique, F-69342 Lyon, France.
We introduce a new paradigm for the preparation of deeply entangled states useful for quantum metrology. We show that, when the quantum state is an eigenstate of an operator A, observables G which are completely off diagonal with respect to A have purely quantum fluctuations, as quantified by the quantum Fisher information, namely, F_{Q}(G)=4⟨G^{2}⟩. This property holds regardless of the purity of the quantum state, and it implies that off-diagonal fluctuations represent a metrological resource for phase estimation.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Laboratoire Matériaux et Phénomènes Quantiques, Université Paris Cité, CNRS UMR 7162, 75013 Paris, France.
We present a method to systematically identify and classify quantum optical nonclassical states as classical or nonclassical based on the resources they create on a bosonic quantum computer. This is achieved by converting arbitrary bosonic states into multiple modes, each occupied by a single photon, thereby defining qubits of a bosonic quantum computer. Starting from a bosonic classical-like state in a representation that explicitly respects particle number superselection rules, we apply universal gates to create arbitrary superpositions of states with the same total particle number.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Sun Yat-sen University, School of Physics and Astronomy, Zhuhai 519082, China.
Vortex states of photons, electrons, and other particles are freely propagating wave packets with helicoidal wave fronts winding around the axis of a phase vortex. A particle prepared in a vortex state carries a nonzero orbital angular momentum projection on the propagation direction, a quantum number that has never been exploited in experimental particle and nuclear physics. Low-energy vortex photons, electrons, neutrons, and helium atoms have been demonstrated in experiment and found numerous applications, and there exist proposals of boosting them to higher energies.
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