Probing magnetic ordering in air stable iron-rich van der Waals minerals

In the rapidly expanding field of two-dimensional materials, magnetic monolayers show great promise for the future applications in nanoelectronics, data storage, and sensing. The research in intrinsically magnetic two-dimensional materials mainly focuses on synthetic iodide and telluride based compounds, which inherently suffer from the lack of ambient stability. So far, naturally occurring layered magnetic materials have been vastly overlooked. These minerals offer a unique opportunity to explore air-stable complex layered systems with high concentration of local moment bearing ions. We demonstrate magnetic ordering in iron-rich two-dimensional phyllosilicates, focusing on mineral species of minnesotaite, annite, and biotite. These are naturally occurring van der Waals magnetic materials which integrate local moment baring ions of iron via magnesium/aluminium substitution in their octahedral sites. Due to self-inherent capping by silicate/aluminate tetrahedral groups, ultra-thin layers are air-stable. Chemical characterization, quantitative elemental analysis, and iron oxidation states were determined via Raman spectroscopy, wavelength disperse X-ray spectroscopy, X-ray absorption spectroscopy, and X-ray photoelectron spectroscopy. Superconducting quantum interference device magnetometry measurements were performed to examine the magnetic ordering. These layered materials exhibit paramagnetic or superparamagnetic characteristics at room temperature. At low temperature ferrimagnetic or antiferromagnetic ordering occurs, with the critical ordering temperature of 38.7 K for minnesotaite, 36.1 K for annite, and 4.9 K for biotite. In-field magnetic force microscopy on iron bearing phyllosilicates confirmed the paramagnetic response at room temperature, present down to monolayers.Comment: 19 pages, 6 figure

Microextraction of polychlorinated biphenyls (PCBS) from soil samples

The standard method of polychlorinated biphenyl (PCB) analysis in soil samples requires Soxhlet extraction of gram amount of sample, considerable amounts of hazardous solvents, and a clean-up and extraction time of 3 days per sample. An efficient microextraction procedure has been developed for the trace quantitative analysis of PCBs in soil samples that will only necessitate a small fraction of the Soxhlet extraction requirements ad still achieve good recoveries for PCB congeners. The microextrcation procedures requires only 0.1g amount of sample and is relatively inexpensive extraction technique, which can be completed within 18 hours. The technique uses standard glassware and only minimal amount of solvent. In this work, parameters such as the type and amount of extracting solvent were evaluated. The congener-specific recoveries of the 20 target PCBs were compared using hexane and heptane as extracting solvents. When compared to the certified concentrations of the 20 congeners in the soil standard reference material (SRM) from the National Institute of Standards and Technology (NIST), the proposed microextraction method using heptane showed excellent recoveries for 10 of the congeners. The other 10 target congeners were found with other PCB congeners or contaminants. Moreover, the recoveries of the 2 surrogate internal standards, PCB #30 and 112, were also within the acceptable limit of ±30% even at 25 ng/g

Measurements of Groomed-Jet Substructure of Charm Jets Tagged by D0 Mesons in Proton-Proton Collisions at s\sqrt{s} =13 TeV

Understanding the role of parton mass and Casimir color factors in the quantum chromodynamics parton shower represents an important step in characterizing the emission properties of heavy quarks. Recent experimental advances in jet substructure techniques have provided the opportunity to isolate and characterize gluon emissions from heavy quarks. In this Letter, the first direct experimental constraint on the charm-quark splitting function is presented, obtained via the measurement of the groomed shared momentum fraction of the first splitting in charm jets, tagged by a reconstructed D0 meson. The measurement is made in proton-proton collisions at s=13 TeV, in the low jet transverse-momentum interval of 15≤pTjet ch<30 GeV/c where the emission properties are sensitive to parton mass effects. In addition, the opening angle of the first perturbative emission of the charm quark, as well as the number of perturbative emissions it undergoes, is reported. Comparisons to measurements of an inclusive-jet sample show a steeper splitting function for charm quarks compared with gluons and light quarks. Charm quarks also undergo fewer perturbative emissions in the parton shower, with a reduced probability of large-angle emissions

Exclusive and dissociative J/ψ photoproduction, and exclusive dimuon production, in p-Pb collisions at sNN\sqrt{s_{NN}} = 8.16 TeV

The ALICE Collaboration reports three measurements in ultraperipheral proton-lead collisions at forward rapidity. The exclusive two-photon process γγ→μ+μ- and the exclusive photoproduction of J/ψ are studied. J/ψ photoproduction with proton dissociation is measured for the first time at a hadron collider. The cross section for the two-photon process of dimuons in the invariant mass range from 1 to 2.5 GeV/c2 agrees with leading-order quantum electrodynamics calculations. The exclusive and dissociative cross sections for J/ψ photoproductions are measured for photon-proton center-of-mass energies from 27 to 57 GeV. They are in good agreement with HERA results

A consensus protocol for functional connectivity analysis in the rat brain

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Author Correction: A consensus protocol for functional connectivity analysis in the rat brain (Nature Neuroscience, (2023), 26, 4, (673-681), 10.1038/s41593-023-01286-8)

In the version of this article initially published, Clément M. Garin was presented in the author list without a middle initial. The name has been amended in the HTML and PDF versions of the article