Magnetic and microwave absorption properties of Ni_(1-x)Zn_xFe_2O_4 nanocrystalline synthesized by sol-gel method

Ni1-xZnxFe2O4(0≤x≤1,in steps of 0.1) nanocrystallines were synthesized by sol-gel route.The doping effects of zinc on structural,magnetic and microwave absorption properties were investigated in detail.X-ray diffraction(XRD) results show that all the samples are single-phase spinel structure.The magnetic and microwave absorption properties are strongly dependent on the zinc content,which can be understood in terms of the cations redistribution in spinel tetrahedral and octahedral sites with the increase of zinc content.The magnetic measurement shows the antiferromagnetic nature of the samples for x=0.9 and x=1.0.The saturation magnetization reaches the maximum of 3.35μB/f.u.at x=0.5.The optimal reflection loss(RL) of-29.6 dB is found at 6.5 GHz for an absorber thickness of 5 mm.The RL values exceeding 10 dB are obtained for the absorber in the range of 3.9-8.9 GHz.These Ni1-xZnxFe2O4 nanocrystallines may be attractive candidates for electromagnetic wave absorption materials.

Gravitational wave astrophysics, data analysis and multimessenger astronomy

This paper reviews gravitational wave sources and their detection. One of the most exciting potential sources of gravitational waves are coalescing binary black hole systems. They can occur on all mass scales and be formed in numerous ways, many of which are not understood. They are generally invisible in electromagnetic waves, and they provide opportunities for deep investigation of Einstein's general theory of relativity. Sect. 1 of this paper considers ways that binary black holes can be created in the universe, and includes the prediction that binary black hole coalescence events are likely to be the first gravitational wave sources to be detected. The next parts of this paper address the detection of chirp waveforms from coalescence events in noisy data.Such analysis is computationally intensive. Sect. 2 reviews a new and powerful method of signal detection based on the GPUimplemented summed parallel infinite impulse response filters. Such filters are intrinsically real time alorithms, that can be used to rapidly detect and localise signals. Sect. 3 of the paper reviews the use of GPU processors for rapid searching for gravitational wave bursts that can arise from black hole births and coalescences. In sect. 4 the use of GPU processors to enable fast efficient statistical significance testing of gravitational wave event candidates is reviewed. Sect. 5 of this paper addresses the method of multimessenger astronomy where the discovery of electromagnetic counterparts of gravitational wave events can be used to identify sources, understand their nature and obtain much greater science outcomes from each identified event.

The detection of gravitational waves and the new era of multi-messenger astronomy

For the first time,gravitational waves(GWs),a major prediction of Einstein’s 1915 general theory of relativity(GR),has been detected directly by the two detectors of the Laser Interferometer Gravitational-Wave Observatory(LIGO)[1,

Crystal growth,structure and laser performance of a new Yb^(3+):KBaY(MoO_(4))_(3) crystal

A Yb^(3+):KBaY(MoO_(4))_(3)(Yb^(3+):KBYM)crystal with dimensions of 51 mm×27 mm × 10 mm was successfully grown by the TSSG method.The characteristics of the crystal structure and probability of good optical properties were analyzed.The absorption and emission spectra of Yb^(3+):KBYM crystal exhibit broadened bands,with the maximum absorption cross-sections of 1.17 × 10^(-20),1.44×10^(-20) and 1.37 × 10^(-20) cm^(2) at976 nm for X-,Y-and Z-polarizations,respectively.The corresponding absorption FWHMs are as wide as 77,46 and 55 nm.The well-known re-absorption effect of Yb^(3+) in the crystal is discussed.Two methods,the Fiichtbauer-Ladenburg method(FL)and reciprocity method(RM)were adopted to compute the emission cross-sections and results show a certain discrepancy but the errors are allowable.The laser potentiality of the Yb^(3+):KBYM crystal was also evaluated by calculations of minimum inversion fractionβmin,saturation pump intensity Isat,the minimum pump intensity Imin and gain cross-sections spectra.Laser experiment was carried out and Watt-level continuous wave laser has been realized.Results indicate that the Yb^(3+):KBYM crystal with a disordered structure may be a potential laser media that can be used to generate tunable and ultrashort pulse laser emissions with high quality beam.

Performance Analysis of Single Relay Selection in Cooperative Communication over Nakagami-m Fading Channels

We derive closed-form expressions for outage probability and symbol error rate(SER) of opportunistic relaying(OR) and selection cooperation(SC).For the amplify-and-forward relay selection scheme,comparison between two selection strategies over independent non-identically distributed Nakagami-m fading channels via analytical and simulation results is given in terms of the outage probability and SER.Simulation results show that OR performs better than SC.

The first confirmed gravitational wave detection in LIGO's second observational run

In this article,we describe the results concerning the third coincident signal GW170104 from the coalescence of binary black holes(BBHs)during the second observation run(O2).The result was obtained from the LIGO Scientific Collaboration and the Virgo Collaboration.Following the first and second gravitational waves(GWs)detections in the first observation run(O1)[1],recently LIGO has observed a third coincident signal GW170104 from the coalescence of

Multiple plasmon couplings in 3D hybrid Au-nanoparticles-decorated Ag nanocone arrays boosting highly sensitive surface enhanced Raman scattering

Plasmon coupling is an essential strategy to realize strong local electromagnetic(EM)field which is crucial for high-performance plasmonic devices.In this work,multiple plasmon couplings are demonstrated in three-dimensional(3D)hybrid plasmonic systems composed of polydimethylsiloxane-supported ordered silver nanocone(AgNC)arrays decorated with high-density gold nanoparticles(AuNPs)which are fabricated by a template-assisted physical vapor deposition process.Strong interparticle coupling,particle-film coupling,inter-cone coupling,and particle-cone coupling are revealed by numerical simulations in such composite nanostructures,which produce intense and high-density EM hot spots,boosting highly sensitive and reproducible surface enhanced Raman scattering(SERS)detection with an enhancement factor of-1.74×10^(8).Furthermore,a linear correlation between logarithmic Raman intensity and logarithmic concentration of probe molecules is observed in a large concentration range.These results offer new ideas to develop novel plasmonic devices,and provide alternative strategy to realize flexible and high-performance SERS sensors for trace molecule detection and quantitative analysis.

Observatory science with eXTP

In this White Paper we present the potential of the enhanced X-ray Timing and Polarimetry(eXTP) mission for studies related to Observatory Science targets. These include flaring stars, supernova remnants, accreting white dwarfs, low and high mass X-ray binaries, radio quiet and radio loud active galactic nuclei, tidal disruption events, and gamma-ray bursts. eXTP will be excellently suited to study one common aspect of these objects: their often transient nature. Developed by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Science, the eXTP mission is expected to be launched in the mid 2020s.