Ultrasonic Through-Metal Communication Based on Deep-Learning-Assisted Echo Cancellation.

Ultrasound is extremely efficient for wireless signal transmission through metal barriers due to no limit of the Faraday shielding effect. Echoing in the ultrasonic channel is one of the most challenging obstacles to performing high-quality communication, which is generally coped with by using a channel equalizer or pre-distorting filter. In this study, a deep learning algorithm called a dual-path recurrent neural network (DPRNN) was investigated for echo cancellation in an ultrasonic through-metal communication system. The actual system was constructed based on the combination of software and hardware, consisting of a pair of ultrasonic transducers, an FPGA module, some lab-made circuits, etc. The approach of DPRNN echo cancellation was applied to signals with a different signal-to-noise ratio (SNR) at a 2 Mbps transmission rate, achieving higher than 20 dB SNR improvement for all situations. Furthermore, this approach was successfully used for image transmission through a 50 mm thick aluminum plate, exhibiting a 24.8 dB peak-signal-to-noise ratio (PSNR) and a about 95% structural similarity index measure (SSIM). Additionally, compared with three other echo cancellation methods-LMS, RLS and PNLMS-DPRNN has demonstrated higher efficiency. All those results firmly validate that the DPRNN algorithm is a powerful tool to conduct echo cancellation and enhance the performance of ultrasonic through-metal transmission.

Backbone Isomerization to Enhance Thermal Stability and Decrease Mechanical Sensitivities of 10 Nitro-Substituted Bipyrazoles.

The development of novel, environmentally friendly, and high-energy oxidizers remains interesting and challenging for replacing halogen-containing ammonium perchloride (AP). The trinitromethyl moiety is one of the most promising substituents for designing high-energy density oxidizers. In this study, a backbone isomerization strategy was utilized to manipulate the properties of 10 nitro group-substituted bipyrazoles containing the largest number of nitro groups among the bis-azole backbones so far. Another advanced high-energy density oxidizer, 3,3',5,5'-tetranitro-1,1'-bis(trinitromethyl)-1H,1'H-4,4'-bipyrazole (3), was designed and synthesized. Compared to the isomer 4,4',5,5'-tetranitro-2,2'-bis(trinitromethyl)-2H,2'H-3,3'-bipyrazole (4) (Td = 125 °C), 3 possesses better thermostability (Td = 156 °C), which is close to that of ammonium dinitramide (ADN) (Td = 159 °C), and it possesses better mechanical sensitivity (impact sensitivity (IS) = 13 J and friction sensitivity (FS) = 240 N) than that of 4 (IS = 9 J and FS = 215 N), thereby demonstrating a promising perspective for practical applications.

Trinitromethyl Energetic Groups Enhance High Heats of Detonation.

The introduction of groups with high enthalpies of formation can effectively improve the detonation performance of the compounds. A series of novel energetic compounds (10-13) with high enthalpies of formation, high density, and high nitrogen-oxygen content were designed and synthesized by combining gem-polynitromethyl, 1,2,4-oxadiazole, furoxan, and azo groups. All the new compounds were thoroughly characterized by IR, NMR, elemental analysis, and differential scanning calorimetry. Compounds 10 and 11 were also further characterized with single-crystal X-ray diffraction. Compound 11 has high density (1.93 g cm-3), high enthalpy of formation (993.5 kJ mol-1), high detonation velocity (9411 m s-1), and high heat of detonation (6889 kJ kg-1) and is a potentially excellent secondary explosive.

Intramolecular Assembly of Nitrobiazoles and an Ether Bridge: Toward Energetic Materials with Enhanced Energy and Safety.

Recently, the construction of novel fused-ring frameworks has become one of the most significant innovative approaches to access high-energy and thermostable energetic molecules. In this work, an ether bridge was utilized as a building block to construct energetic fused-ring skeletons for the first time. Two new [5,7,5]-tricyclic N-heterocycle-based backbones, ditriazole-1,3,6-oxadiazepine and pyrazole-triazole-1,3,6-oxadiazepine, were synthesized via a straightforward one-step synthetic route and the energetic performances of their derivatives were further evaluated. Containing an additional oxygen atom, high-density pyrazole-triazole backbone, and high crystal packing coefficient, the asymmetric molecule 2,10,11-trinitro-5H,7H-pyrazolo[1,5-c][1,2,4]triazolo[5,1-e][1,3,6]oxadiazepine (NOB-3) features a high crystal density of 1.825 g cm-3, much superior to those of the symmetrical analogues 2,10-dinitro-5H,7H-bis([1,2,4]triazolo)[1,5-c:5',1'-e][1,3,6]oxadiazepine (NOB-4, d = 1.758 g cm-3) and D (d = 1.634 g cm-3). Meanwhile, the compounds NOB-3 and NOB-4 exhibit better thermal stability than the parent molecule DNBT (Td = 251 °C), and their decomposition temperatures reach up to 303 and 294 °C, respectively. The remarkable overall performance of NOB-3 and NOB-4 strongly suggests them as appropriate candidates for heat-resistant explosives. Our study may give new insights into the close correlation of the structural properties of energetic fused-ring frameworks, and the universality of the asymmetric heterocycles combination strategy for designing advanced high-energy density materials (HEDMs) was emphasized again.

Evaluating Different Extraction Approaches for GC-MS Based Metabolomics Analysis of the Giant Pandas' Fur.

Giant pandas in zoo captivity are situated in residential areas, where environmental pollutants and anthropogenic factors have an impact on their health. Hair metabolomics has been applied in numerous environmental toxicological studies. Therefore, the panda fur metabolome could be a reliable approach to reflect endogenous and exogenous metabolic changes related to environmental exposure. However, there is no established extraction protocol to study the fur metabolome of pandas. The aim of this research was to optimize the extraction of panda fur metabolome for high-throughput metabolomics analysis using gas chromatography-mass spectrometry. Fur samples were collected from five pandas. Eight different extraction methods were investigated and evaluated for their reproducibility, metabolite coverage, and extraction efficiency, particularly in relation to the biochemical compound classes such as amino acids, tricarboxylic acid cycle derivatives, fatty acids, and secondary metabolites. Our results demonstrated that HCl + ACN were the superior extraction solvents for amino acid and secondary metabolite extraction, and NaOH + MeOH was ideal for fatty acid extraction. Interestingly, the metabolomic analysis of panda fur was capable of discriminating the longitudinal metabolite profile between black and white furs. These extraction protocols can be used in future study protocols for the analysis of the fur metabolome in pandas.

Enhancement of Energetic Performance through the Construction of Trinitromethyl Substituted ß-Bis(1,2,4-oxadiazole).

Halogen-free substitutions of ammonium perchlorate (AP), which meet the requirements of high density, high performance, and acceptable stability, have been a subject of scientific research for many years. In this work, by regrouping atoms in trinitromethyl substituted bis(1,2,4-oxadiazole), a novel oxidizer, trinitromethyl substituted ß-bis(1,2,4-oxadiazole) (3), was designed and synthesized. It possesses an improved density (ρ = 2.002 g cm-3 at 170 K, ρ = 1.942 g cm-3 at 298 K) and thermal stability (Td = 142.8 °C) in comparison to its regioisomer 5,5'-bis(trinitromethyl)-3,3'-bi(1,2,4-oxadiazole) (E). The properties for 3 were studied by both experimental and theoretical methods. The high positive oxygen balance of +7.3% and high specific impulse of 250 s also make compound 3 a promising candidate for an energetic oxidizer.

Deletion Mutants of the Attenuated Recombinant ASF Virus, BA71ΔCD2, Show Decreased Vaccine Efficacy.

African swine fever (ASF) has become the major threat to the global swine industry. Lack of available commercial vaccines complicates the implementation of global control strategies. So far, only live attenuated ASF viruses (ASFV) have demonstrated solid protection efficacy at the experimental level. The implementation of molecular techniques has allowed the generation of a collection of deletion mutants lacking ASFV-specific virulence factors, some of them with promising potential as vaccine candidates against the pandemic genotype II ASFV strain currently circulating in Africa, Europe, Asia and Oceania. Despite promising results, there is room for improvement, mainly from the biosafety point of view. Aiming to improve the safety of BA71∆CD2, a cross-protective recombinant live attenuated virus (LAV) lacking the ASFV CD2v gene (encoding ß-glucuronidase as a reporter gene) available in our laboratory, three new recombinants were generated using BA71∆CD2 as a template: the single mutant BA71∆CD2f, this time containing the fluorescent mCherry reporter gene instead of CD2v, and two double recombinants lacking CD2v and either the lectin gene (EP153R) or the uridine kinase (UK) gene (DP96R). Comparative in vivo experiments using BA71∆CD2f, BA71∆CD2DP96R and BA71∆CD2EP153R recombinant viruses as immunogens, demonstrated that deletion of either DP96R or EP153R from BA71∆CD2f decreases vaccine efficacy and does not improve safety. Our results additionally confirm ASFV challenge as the only available method today to evaluate the protective efficacy of any experimental vaccine. We believe that understanding the fine equilibrium between attenuation and inducing protection in vivo deserves further study and might contribute to more rational vaccine designs in the future.

Fecal microbiota transplantation from warthog to pig confirms the influence of the gut microbiota on African swine fever susceptibility.

African swine fever virus (ASFV) is the causative agent of a devastating hemorrhagic disease (ASF) that affects both domestic pigs and wild boars. Conversely, ASFV circulates in a subclinical manner in African wild pigs, including warthogs, the natural reservoir for ASFV. Together with genetic differences, other factors might be involved in the differential susceptibility to ASF observed among Eurasian suids (Sus scrofa) and African warthogs (Phacochoerus africanus). Preliminary evidence obtained in our laboratory and others, seems to confirm the effect that environmental factors might have on ASF infection. Thus, domestic pigs raised in specific pathogen-free (SPF) facilities were extremely susceptible to highly attenuated ASFV strains that were innocuous to genetically identical domestic pigs grown on conventional farms. Since gut microbiota plays important roles in maintaining intestinal homeostasis, regulating immune system maturation and the functionality of the innate/adaptive immune responses, we decided to examine whether warthog fecal microbiota transplantation (FMT) to domestic pigs affects host susceptibility to ASFV. The present work demonstrates that warthog FMT is not harmful for domestic weaned piglets, while it modifies their gut microbiota; and that FMT from warthogs to pigs confers partial protection against attenuated ASFV strains. Future work is needed to elucidate the protective mechanisms exerted by warthog FMT.

Interleukin-21 receptor gene polymorphism is associated with hepatitis B virus-related hepatocellular carcinoma in Chinese patients.

BACKGROUND: We investigated the relationship between hepatitis B virus (HBV)-related pathogenesis and single nucleotide polymorphisms (SNPs) in interleukin-21 (IL-21)-JAK-STAT signaling pathway genes. METHODS: We used the high-resolution melting (HRM) method to genotype five SNPs (IL-21 rs2221903, IL-21 rs4833837, IL-21 receptor (IL-21R) rs2285452, JAK3 rs3008, and STAT3 rs1053023) in 546 HBV-infected patients and 353 healthy Chinese subjects. The HBV-infected patients were further divided into subgroups based on the HBV-related pathologies: chronic hepatitis B (CHB), HBV-related liver cirrhosis (LC), and HBV-related hepatocellular carcinoma (HCC). RESULTS: There were no significant differences in the genotype and allele distributions of the five SNPs between the HBV-infected patients and healthy subjects. The genotype and allele frequencies were similar in the two groups for IL-21 rs2221903 (A>G, P = 0.83 and 0.67), rs4833837 (A>G, P = 0.80 and 0.49), IL-21R rs2285452 (G>A, P = 0.25 and 0.68), STAT3 rs1053023 (A>G, P = 1.00 and 0.96), and JAK3 rs3008 (C>T, P = 0.32 and 0.54). However, patients with the IL-21R rs2285452 AA genotype were more susceptible to HBV-related HCC than those with the IL-21R rs2285452 GA/GG genotype (P = 0.03, OR = 3.27, 95% CI = 1.16-9.20). The serological marker model of "HBsAg+, HBeAg+, HBcAb+" was predominant among patients with HBV infection. However, there was no association between the genotype's distribution of the five SNPs and the serological marker models (P > 0.05). CONCLUSIONS: These findings demonstrate that the IL-21R rs2285452 AA genotype increases the risk of HBV-related HCC in Chinese patients.

A Novel Flexible Full-Cell Lithium Ion Battery Based on Electrospun Carbon Nanofibers Through a Simple Plastic Package.

The paper reports a novel flexible full-cell lithium ion battery (LIB) through a simple plastic package method. Carbon nanofibers (CNFs) are synthesized by electrospinning technology and the subsequent carbonation process. The CNFs with three-dimensional interconnected fibrous nanostructure exhibit a stable reversible capacity of 412 mAh g-1 after 100 cycles in the half-cell testing. A full cell is assembled by using CNF anode and commercial LiCoO2 cathode, and it displays good flexibility and lighting LED ability. The aggregate thickness of the constructed full-cell LIB is approximately 500 µm, consisting of a CNFs/Cu film, a separator, a LiCoO2/Al film, electrolyte, and two polyvinyl chloride (PVC) films. The structure, morphology, and the electrochemical performances of electrospun CNFs and LiCoO2 electrodes are analyzed in details.