High loading BaTiO3 nanoparticles chemically bonded with fluorinated silicone rubber for largely enhanced dielectric properties of polymer nanocomposites.

Integrating high-loading dielectric nanoparticles into polar polymer matrices potentially can profit the intrinsic polarization of each phase and allow for greatly enhanced dielectric properties in polymer nanocomposites. It is however challenging to achieve desirable highly filled polar polymer composites because of the lack of efficient approaches to disperse nanoparticles and maintain interfacial compatibility. Here, we report a versatile route to fabricate highly filled barium titanate/fluorinated silicone rubber (BT/FSR) nanocomposites by "thiol-ene click" and isostatic pressing techniques. The loaded BT nanoparticles (from 82 wt% to 90 wt%) are chemically bonded with FSR in the nanocomposites. The existence of the polar group (-CH2CF3) of the polymer matrix does not affect the uniform dispersion of the nanoparticles or the good interfacial compatibility. The 90 wt% BT/FSR nanocomposite shows the highest dielectric constant of 57.8 at 103 Hz, while the loss tangent can be kept below 0.03. Besides, BT/FSR nanocomposites display higher breakdown strength than BT/SR nanocomposites. This work offers a facile strategy towards superior dielectric properties of polymer nanocomposites.

Animal Rabies Surveillance, China, 2004-2018.

Rabies is a severe zoonotic disease in China, but the circulation and distribution of rabies virus (RABV) within animal reservoirs is not well understood. We report the results of 15 years of surveillance of the first Chinese Rabies Surveillance Plan in animal populations, in which animal brain tissues collected during 2004-2018 were tested for RABV and phylogenetic and spatial-temporal evolutionary analyses performed using obtained RABV sequences. The results have provided the most comprehensive dataset to date on the infected animal species, geographic distribution, transmission sources, and genetic diversity of RABVs in China. In particular, the transboundary transmission of emerging RABV subclades between China and neighboring countries was confirmed. The study highlights the importance of continuous animal rabies surveillance in monitoring the transmission dynamics, and provides updated information for improving current control and prevention strategies at the source.

Analysis and compensation of telescopes' gaps effect on aperture synthesis in a multi-channel synthetic aperture ladar system.

The azimuth multi-channel synthetic aperture ladar (SAL), which arranges multiple telescopes along the flight direction of the platform, transmits signals through a single telescope and receives echoes by multiple telescopes simultaneously to obtain data. The aperture synthesis technology, which has the ability to achieve high resolution through multiple small telescopes, is applied to the multi-channel SAL system to realize the reconstruction of the complete azimuth Doppler spectrum in a short observation time. However, there are gaps inevitably between telescopes, which degrade the results of aperture synthesis. In this work, the effect of gaps on the instantaneous Doppler spectrum of each channel and the influence on the result of the azimuth impulse compression after aperture synthesis are analyzed. In addition, an estimation method of gaps based on the phase errors between channels is proposed to reduce the influence. The estimation accuracy of the proposed method is analyzed, and the effectiveness of the method is verified with simulations. The estimated gaps are used to compensate for the phase discontinuity of the azimuth signal after aperture synthesis caused by gaps. The method improves the result of aperture synthesis and reduces the side-lobe of the azimuth impulse compression after aperture synthesis.

Livestock rabies outbreaks in Shanxi province, China.

Dogs play an important role in rabies transmission throughout the world. In addition to the severe human rabies situation in China, spillover of rabies virus from dogs in recent years has caused rabies outbreaks in sheep, cattle and pigs, showing that there is an increasing threat to other domestic animals. Two livestock rabies outbreaks were caused by dogs in Shanxi province, China from April to October in 2015, resulting in the deaths of 60 sheep, 10 cattle and one donkey. Brain samples from one infected bovine and the donkey were determined to be rabies virus (RABV) positive by fluorescent antibody test (FAT) and reverse transcription polymerase chain reaction (RT-PCR). The complete RABV N genes of the two field strains, together with those of two previously confirmed Shanxi dog strains, were amplified, sequenced and compared phylogenetically with published sequences of the N gene of RABV strains from Shanxi and surrounding provinces. All of the strains from Shanxi province grouped closely, sharing 99.6 %-100 % sequence identity, indicating the wide distribution and transmission of dog-mediated rabies in these areas. This is the first description of donkey rabies symptoms with phylogenetic analysis of RABVs in Shanxi province and surrounding regions. The result emphasizes the need for mandatory dog rabies vaccination and improved public education to eradicate dog rabies transmission.

Optimization of the Thermally Conductive Low-k Polymer Dielectrics Based on Multisource Free-Volume Effects.

Polymers/polymer matrix composites possessing low dielectric constants (low-k polymer dielectrics) contribute to the advance of electronics, for instance, microprocessor chips, mobile phone antennas, and data communication terminals. However, the intrinsic long-chain structural characteristic results in poor thermal conductivities, which draw heat accumulation and undermine the outstanding low-k performance of polymers. Herein, multisource free-volume effects that combine two novel kinds of extra free volume with the known in-cage free volume of polyhedral oligomeric silsesquioxanes (POSSs) are discussed to reduce the capacity for dielectric constant reduction. The multisource free-volume effects of POSSs are associated with the thermal conductive network formed by the hexagonal boron nitride (BN) in the polymer matrix. The results show a decent balance between low-k performance (dielectric constant is 2.08 at 1 MHz and 1.98 at 10 GHz) and thermal conductivity (0.555 W m-1 K-1, 4.91 times the matrix). The results provide a new idea to maximize the free-volume effects of POSSs to optimize dielectric properties together with other desired performances for the dielectrics.

Leakage-Proof Flexible Phase Change Gels with Salient Thermal Conductivity for Efficient Thermal Management.

Phase change materials (PCMs) as one of the most potential latent heat storage techniques have been widely used for thermal management and energy storage. However, simultaneously imparting flexibility, high thermal conductivity, and considerable energy storage density to organic PCMs remains challenging. In this work, a coupling strategy combining substance exchange and magnetic orientation has been proposed to fabricate phase change gels (PCGs) with thermally induced flexibility and high through-plane thermal conductivity. In the PCGs, synthesized boron nitride/ferroferric oxide (BN@Fe3O4) particles and polyacrylic acid (PAA) precursor liquid are introduced to polyethylene glycol (PEG) aqueous solution, and a magnetic field is applied in the process of PAA network construction to promote ordered arrangement of BN@Fe3O4 along the direction of the magnetic field. Consequently, PEG is wrapped by the cross-linked PAA supporting network, forming PCGs with excellent shape stability and thermally induced flexibility. The vertical orientation structure of BN@Fe3O4 endows the PCGs with an enhanced through-plane thermal conductivity of up to 1.07 W m-1 K-1 at a BN@Fe3O4 loading of 25.6 wt % with an additional enhancement of 215% compared to the composite without BN. The thermally conductive leakage-proof PCGs present great application potential in heat storage and management.

Diversity of rabies virus detected in Inner Mongolia, China, 2019-2021.

Rabies is a serious public health issue in China, with over 95% of human infections transmitted by dogs. As part of a routine surveillance carried out in the Inner Mongolia Autonomous Region (IMAR) between 2019 and 2021, 80 of 95 suspected rabies cases in domestic animals (dogs, livestock) and wild carnivores (foxes, badgers, a raccoon dog) were confirmed as rabies virus (RABV) positive. Phylogenetic analysis of RABVs of the 80 cases based on complete N genes showed that 97.5% (78/80) of the virus strains belonged to the Cosmopolitan (steppe-type) clade, with one in each of Arctic-related (AL2) and Asian (SEA1) clades. The data show that infected foxes have become a major transmission source of rabies in China, second only to dogs, and play a pivotal role in animal rabies epizootics in the north and northwest of the country. The recent spread of fox rabies to other animal species presents an increasing threat to public health and emphasizes the importance of animal rabies surveillance.

Semisupervised Text Classification by Variational Autoencoder.

Semisupervised text classification has attracted much attention from the research community. In this paper, a novel model, the semisupervised sequential variational autoencoder (SSVAE), is proposed to tackle this problem. By treating the categorical label of unlabeled data as a discrete latent variable, the proposed model maximizes the variational evidence lower bound of the data likelihood, which implicitly derives the underlying label distribution for the unlabeled data. Analytical work indicates that the autoregressive nature of the sequential model is the crucial issue that renders the vanilla model ineffective. To remedy this, two types of decoders are investigated in the SSVAE model and verified. In addition, a reweighting approach is proposed to circumvent the credit assignment problem that occurs during the reconstruction procedure, which can further improve performance for sparse text data. Experimental results show that our method significantly improves the classification accuracy compared with other modern methods.

Evaluation of a Universal Nested Reverse Transcription Polymerase Chain Reaction for the Detection of Lyssaviruses.

To detect rabies virus and other member species of the genus Lyssavirus within the family Rhabdoviridae, the pan-lyssavirus nested reverse transcription polymerase chain reaction (nested RT-PCR) was developed to detect the conserved region of the nucleoprotein (N) gene of lyssaviruses. The method applies reverse transcription (RT) using viral RNA as template and oligo (dT)15 and random hexamers as primers to synthesize the viral complementary DNA (cDNA). Then, the viral cDNA is used as a template to amplify an 845 bp N gene fragment in first-round PCR using outer primers, followed by second-round nested PCR to amplify the final 371 bp fragment using inner primers. This method can detect different genetic clades of rabies viruses (RABV). The validation, using 9,624 brain specimens from eight domestic animal species in 10 years of clinical rabies diagnoses and surveillance in China, showed that the method has 100% sensitivity and 99.97% specificity in comparison with the direct fluorescent antibody test (FAT), the gold standard method recommended by the World Health Organization (WHO) and the World Organization for Animal Health (OIE). In addition, the method could also specifically amplify the targeted N gene fragment of 15 other approved and two novel lyssavirus species in the 10th Report of the International Committee on Taxonomy of Viruses (ICTV) as evaluated by a mimic detection of synthesized N gene plasmids of all lyssaviruses. The method provides a convenient alternative to FAT for rabies diagnosis and has been approved as a National Standard (GB/T36789-2018) of China.

Evaluation of monoclonal antibody-based direct, rapid immunohistochemical test for rabies diagnosis.

Rabies is a major public health problem in developing countries in Asia and Africa. Although a number of laboratory diagnoses can be used for rabies control, the WHO and OIE recommended gold standard for rabies diagnosis is the direct fluorescent antibody test (FAT). However, FAT is not widely used in developing countries because of deficient financial sources to procure fluorescent microscope. Recently the direct rapid immunohistochemical test (dRIT) has been developed and has a worldwide promising application, particularly in developing countries, since its result can be read by inexpensive light microscopy, in addition to be consistent with that of FAT. However, no commercial conjugated antibody is available to meet the laboratory demand. We describe here the production of a monoclonal antibody (MAb) against rabies virus (RABV) N protein and its use as a biotinylated conjugate in a dRIT. Tested against a batch of 107 brain specimens representing a wide phylogenetic diversity of RABV collected from different animal species with multiple geographical origins in China, results showed that the dRIT had 100% specificity (95% CI 0.93-1.00) and 96.49% sensitivity (95% CI 0.88-1.00) as compared with the gold standard FAT. It therefore provides a simple, economical alternative to FAT, particularly for use in rabies diagnosis in developing countries.