In this article, an acetone-enhanced negative photoionization (AENP) source based on a 10. 6 eV vacuum ultraviolet ( VUV) lamp was developed and coupled to a home-made time-of-flight mass spectrometer for rapid detection of trace explosives. In the AENP source, acetone molecules absorbed 10. 6 eV photons and were ionized by single photon ionization to emit photoelectrons. The photoelectrons reacted with O2 , CO2 , etc. in the atmosphere to produce mainly CO-3 negative reactant ions. With this ionization source, common explosives, N-nitrobiz ( 2-hyolorolroxy ethyl )-amine dinitrate ( DINA ) , Tetryl, trinitrotoluene ( TNT ) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), could be detected sensitively, and the limit of detection of 2 pg ( TNT) with a linear range of 3 orders of magnitude was achieved. The simple structure, high sensitivity characteristics make the AENP source as a promising ionization source for mass spectrometry.

Reduced sulfur compounds ( RSCs) are one of the main pollutant species in the atmosphere, so it is of great significance to develop a rapid and on-line approaches for their detection. In this study, a portable time-of-flight mass spectrometer ( TOF-MS) with magnetic field enhanced photoelectron ionization source was designed to detect RSCs. The photoelectron ionization source was induced from vacuum ultraviolet photons which generated from vacuum ultraviolet (VUV) lamp with energy of 10. 6 eV. The energy of photoelectrons was controlled by adjusting the extraction voltage to produce the photoelectron ionization, and an annular magnet was used in the ionization region to improve the ionization efficiency of photoelectrons. From the simulation result by SIMION software, it was found that the introduction of magnet field made the motion trajectroies of electrons in the helical motion increase and the convergence of electron at the ionization source was achieved. Experimental results showed that after introducing the magnet filed, the sensitivity of H2 S, SO2 and CS2 was improved by a factor of 5. 3, 9. 4 and 6. 9, respectively. With a detection time of 50 s, the limits of detection for H2S, SO2 and CS2 were 0. 14, 0. 52 and 0. 31 mg/m3(S/N=3), respectively. It could be concluded that the portable TOF-MS with magnetic field enhanced photoelectron ionization source has great potential to be applied for on-line monitoring of volatile sulfides at the emission source.

Given that the current Newcastle disease virus (NDV) infection in wild birds poses the threat to poultry, surveillance of Newcastle disease in captive wild birds was carried out in Jilin, China in 2018. Here, an NDV strain obtained from toco toucan was firstly characterized.The results showed that the F gene of the NDV isolate Toucan/China/3/2018 is classified as genotype II in class II. Sequence analysis of the F0 cleavage site was 113 RQGR/L 117 , which supports the result of the intracerebral pathogenicity index assay indicating classification of the isolate as low-pathogenicity. Experimental infection demonstrated that Toucan/ China/3/2018 can effectively replicate and transmit among chickens. To our knowledge, this is the first report on genetically and pathogenically characterizing NDV strain isolated from toucan, which enriches the epidemiological information of NDV in wild birds.

Drug delivery with customized combinations of drugs, controllable drug dosage, and on-demand release kinetics is critical for personalized medicine. In this study, inspired by successive opening of layered structures and compartmentalized structures in plants, we designed a multiple compartmentalized capsular structure for controlled drug delivery. The structure was designed as a series of compartments, defined by the gradient thickness of their external walls and internal divisions. Based on the careful choice and optimization of bioinks composed of gelatin, starch, and alginate, the capsular structures were successfully manufactured by fused deposition modeling three-dimensional (3D) printing. The capsules showed fusion and firm contact between printed layers, forming complete structures without significant defects on the external walls and internal joints. Internal cavities with different volumes were achieved for different drug loading as designed. In vitro swelling demonstrated a successive dissolving and opening of external walls of different capsule compartments, allowing successive drug pulses from the capsules, resulting in the sustained release for about 410 min. The drug release was significantly prolonged compared to a single burst release from a traditional capsular design. The bioinspired design and manufacture of multiple compartmentalized capsules enable customized drug release in a controllable fashion with combinations of different drugs, drug doses, and release kinetics, and have potential for use in personalized medicine.