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We show how one can test the cosmological Poisson equation by requiring only the validity of three main assumptions: the energy-momentum conservation equations of matter, the equivalence principle, and the cosmological principle. We first point out that one can only measure the combination M ≡ Ω m (0) μ , where μ quantifies the deviation of the Poisson equation from the standard one and Ω m (0) is the fraction of matter density at present. Then we employ a recent model-independent forecast for the growth rate f (z) and the expansion rate E (z) to obtain constraints on M for a survey that approximates a combination of the Dark Energy Spectroscopic Instrument (DESI) and Euclid. We conclude that a constant M can be measured with a relative error σ M = 4.5 % , while if M is arbitrarily varying in redshift, it can be measured only to within 13.4% (1 σ c.l.) at redshift z = 0.9 , and 15-22% up to z = 1.5. We also project our constraints on some parametrizations of M proposed in literature, while still maintaining model-independence for the background expansion, the power spectrum shape, and the non-linear corrections. Generally speaking, as expected, we find much weaker model-independent constraints than found so far for such models. This means that the cosmological Poisson equation remains quite open to various alternative gravity and dark energy models. [ABSTRACT FROM AUTHOR]

In this study, multiple rare earth elements were introduced to modify the multiferroic properties of BiFeO 3. The effects of co-substitution on the structural evolution and properties were thoroughly investigated. With increasing substitution content, the ceramics underwent a symmetry transition from R 3 c to Pna 2 1 and finally to Pbnm. Co-substitution significantly enhanced the ferroelectric properties, with the highest remanent polarization of 33.14 μC/cm² observed at x = 0.10. Due to the symmetry evolution, ferromagnetism was released from the cycloidal spin structure, and the hysteresis loop gradually saturated, with the highest remanent magnetization (M r) of 0.25 emu/g observed at x = 0.16. The concurrent improvement in ferroelectricity and ferromagnetism resulted in substantial magnetoelectric coupling performance, with α ME = 3.50 mV/(cm·Oe). Moreover, direct current poling significantly induced the reverse transition from R 3 c to Pna 2 1 , indicating the potential for electrically controlled magnetism. This study provides a new perspective for modifying the magnetoelectric properties of BiFeO 3. [ABSTRACT FROM AUTHOR]

As a persistent and widespread toxic organic pollutant in the environment, perfluorooctane sulfonate (PFOS) has the potential to cause great harm to wildlife. In our study, the effects of PFOS on neurodevelopment gene expression, neurotransmitter content, neuronal morphology, acetylcholinesterase (AChE) activity were examined, and the potential neurotoxicity mechanisms of PFOS were also investigated in planarians, Dugesia japonica . Using quantitative real-time PCR analysis, five neurodevelopmental related genes were measured, among which, DjotxA , DjotxB , DjFoxD , and DjFoxG were found to be down-regulated, while Djnlg was found to be up-regulated, following exposure to PFOS for 10 days compared with control groups. In addition, the neurotransmitters including dopamine, serotonin, and γ-aminobutyricacid as well as the acitivity of AChE were altered by PFOS exposure. Furthermore, PFOS exposure altered brain morphology as well as smaller cephalic ganglia which displayed reduced nerve fiber density decreased brain branches compared to controls. Our results demonstrate that neurotransmission was disturbed after exposure to PFOS and that exposure to this pollutant can cause neurotoxic defects. Results from this study provide valuable information regarding the neuro- and ecological toxicity of PFOS in aquatic animals and aquatic environments. [ABSTRACT FROM AUTHOR]