Preparation and characterization of carboxyl-group functionalized superparamagnetic nanoparticles and t he potential for bio-applications

In this work, a method was developed to prepare monodispersed carboxyl-group functionalized magnetic nanoparticles. Nanosized maghemite (y-Fe2O3, 7.0 ± 1.0 nm) was synthesized using thermal co-precipitation method and subsequently coated with functional groups by one-step suspension copolymerization. The Fourier transform infrared spectroscopy study and thermogravitmetric analyses confirmed the successful functionalization of carboxyl groups on the surface of magnetic nanocrystals. The surface chemistry makes it possible for SPRI (solid phase reversible immobilization)-based DNA purification. Thus the nanoparticles were employed to isolate plasmid DNA from bacterial cell culture and the results demonstrated its applicability in DNA preparation

Observing white dwarf tidal stripping with TianQin gravitational wave observatory

Recently discovered regular X-ray bursts known as quasi-periodic eruptions have a proposed model that suggests a tidal stripping white dwarf inspiralling into the galaxy's central black hole on an eccentric orbit. According to this model, the interaction of the stripping white dwarf with the central black hole would emit gravitational wave signals as well, their detection can help explore the formation mechanism of quasi-periodic eruptions and facilitate multi-messenger observations. In this paper, we aim to perform a preliminary study of the gravitation wave observation of TianQin on this stripping white dwarf model. We investigated the horizon distance of TianQin on this type of gravitation wave signal and found it can be set to 200Mpc. We also find that those stripping white dwarf model sources with central black hole mass within $10^4\sim10^{5.5}M_\odot$ are more likely to be detected by TianQin. We assessed the parameter estimation precision of TianQin on those stripping white dwarf model sources. Our result shows that, even in the worst case, TianQin can determine the central black hole mass, the white dwarf mass, the central black hole spin, and the orbital initial eccentricity with a precision of $10^{-2}$. In the optimistic case, TianQin can determine the central black hole mass and the white dwarf mass with a precision of $10^{-7}$, determine the central black hole spin with a precision of $10^{-5}$, and determine the orbital initial eccentricity with a precision of $10^{-8}$. Moreover, TianQin can determine the luminosity distance with a precision of $10^{-1}$ and determine the sky localization with a precision of $10^{-2}\sim10$ $\rm deg^2$.Comment: 9 pages, 4 figure

ATP Released by Astrocytes Mediates Glutamatergic Activity-Dependent Heterosynaptic Suppression

AbstractExtracellular ATP released from axons is known to assist activity-dependent signaling between neurons and Schwann cells in the peripheral nervous system. Here we report that ATP released from astrocytes as a result of neuronal activity can also modulate central synaptic transmission. In cultures of hippocampal neurons, endogenously released ATP tonically suppresses glutamatergic synapses via presynaptic P2Y receptors, an effect that depends on the presence of cocultured astrocytes. Glutamate release accompanying neuronal activity also activates non-NMDA receptors of nearby astrocytes and triggers ATP release from these cells, which in turn causes homo- and heterosynaptic suppression. In CA1 pyramidal neurons of hippocampal slices, a similar synaptic suppression was also produced by adenosine, an immediate degradation product of ATP released by glial cells. Thus, neuron-glia crosstalk may participate in activity-dependent synaptic modulation