Towards understanding the lower CH4 selectivity of HCP-Co than FCC-Co in Fischer-Tropsch synthesis.

In Fischer-Tropsch synthesis (FTS), the cobalt catalyst has higher C5+ and lower CH4 selectivity in the hcp phase than in the fcc phase. However, a detailed explanation of the intrinsic mechanism is still missing. The underlying reason was explored combining density functional theory, Wulff construction, and a particle-level descriptor based on the slab model of surfaces that are prevalent in the Wulff shape to provide single-particle level understanding. Using a particle-level indicator of the reaction rates, we have shown that it is more difficult to form CH4 on hcp-Co than on fcc-Co, due to the larger effective barrier difference of CH4 formation and C-C coupling on hcp-Co particles, which leads to the lower CH4 selectivity of hcp-Co in FTS. Among the exposed facets of fcc-Co, the (311) surface plays a pivotal role in promoting CH4 formation. The reduction of CH4 selectivity in cobalt-based FTS is achievable through phase engineering of Co from fcc to hcp or by tuning the temperature and size of the particles.

Improved dispersion-encoded full-range spectral interferometry for large depth, large inclination and rough samples.

In this study, we provide and validate an enhanced dispersion-encoded full-range spectral interferometry that offers improved measurement accuracy for samples characterized by significant depth, inclination, and roughness. Due to the low intensity of the optical signal in these samples, the optical signal is easy to be overwhelmed by the disturbance terms, demanding a more precise phase compensation. To address this issue, the direct current is removed by subtracting the envelope of the interference spectrum, allowing the weak signal near zero optical delay can be identified. Besides, considering the unwrapped phase error caused by the spectrometer aberrations, only the data with good phase continuity are preserved, which improves the accuracy of phase compensation. Using the proposed technique, the depth measurement range of the system is extended from 6 mm to 12 mm, while achieving an axial measurement precision of 2.5µm. In addition, the full-depth images of a ceramic standard step block and a 3D-printed sample are measured. It shows that our system exhibits superior adaptation to complex surfaces compared to the laser line profiler.

An Efficient Way to Model Complex Iron Carbides: A Benchmark Study of DFTB2 against DFT.

Iron carbides have attracted increasing attention in recent years due to their enormous potential in catalytic fields, such as Fischer-Tropsch synthesis and the growth of carbon nanotubes. Theoretical calculations can provide a more thorough understanding of these reactions at the atomic scale. However, due to the extreme complexity of the active phases and surface structures of iron carbides at the operando conditions, calculations based on density functional theory (DFT) are too costly for realistically large models of iron carbide particles. Therefore, a cheap and efficient quantum mechanical simulation method with accuracy comparable to DFT is desired. In this work, we adopt the spin-polarized self-consistent charge density functional tight-binding (DFTB2) method for iron carbides by reparametrization of the repulsive part of the Fe-C interactions. To assess the performance of the improved parameters, the structural and electronic properties of iron carbide bulks and clusters obtained with DFTB2 method are compared with the previous experimental values and the results obtained with DFT approach. Calculated lattice parameters and density of states are close to DFT predictions. The benchmark results show that the proposed parametrization of Fe-C interactions provides transferable and balanced description of iron carbide systems. Therefore, spin-polarized DFTB2 is valued as an efficient and reliable method for the description of iron carbide systems.

d-Orbital Reconstructions Forced by Double Bow-Shaped Deformations and Second Coordination Sphere Effects of Cu(II) Heme Analogs in HER.

Both geometric architecture and electronic configurations of heme proteins contribute to its activity. In this work we designed and synthesized a series of four copper(II) porphyrin complexes (4-, 3-, 2- and 1-Cu) where the molecular conformations are modulated by a pair of stepwise shortened straps on the same porphyrin side (cis-ortho) to give double bow-shaped skeletons. Single crystal structures demonstrate that the straps gradually increase the saddle deformation and the deviation of the metal centers, which is in accordance with two, unusual d-orbital reconstructions of two different ground states, as revealed by 4 K EPR and DFT calculations. In the study of the electrocatalytic hydrogen evolution reaction (HER), 1-Cu, with the shortest straps, showed the most apparent improvement of activity. Second coordination sphere (SCS) effects created by the double bow-shaped architecture and the strong saddle porphyrin core in 1-Cu are found to play key roles in proton trapping during the catalytic process. The work contributes a novel strategy to improve the catalytic performance of heme analogs through ligand geometric modulation.

Electronic Configurations and the Effect of Peripheral Substituents of (Nitrosyl)iron Corroles.

There have been debates on the electronic configurations of (nitrosyl)iron corroles for decades. In this work, pentacoordinate [Fe(TPC)(NO)], [Fe(TTC)(NO)], and [Fe(TpFC)(NO)] with different para-substituted phenyl groups (TPC, TTC, and TpFC = tris(phenyl, 4-tolyl, or 4-fluorophenyl)corrole, respectively) have been isolated and investigated by various techniques including single-crystal X-ray diffraction, UV-vis spectroscopy, cyclic voltammetry, Fourier transform infrared, NMR, and absorption fine structure spectroscopy. Multitemperature and high-magnetic-field (3, 6, and 9 T) Mössbauer spectroscopy was also applied on all three complexes, which determined the S = 0 diamagnetic states, consistent with the magnetic susceptibility and electron paramagnetic resonance measurements. Density functional theory predictions by different functionals were compared, and the new calculation strategy, which gave remarkable agreement of the experimental Mössbauer parameters (ΔEQ and δ), allowed further assignment on the electronic configuration of {FeNO}6-(corrole3-) with antiferromagnetically coupled (S = 1/2, FeIII) and (S = 1/2, NO). Correlated sequences between the electronic donating/withdrawing capability of para substituents and the reduction/oxidation potentials, metal out-of-plane displacements (Δ4 and Δ23), and Mössbauer parameters (Vzz and ΔEQ) were also established, which suggests the strong effects of peripheral substituents.

Unsupervised Deep Anomaly Detection for Medical Images Using an Improved Adversarial Autoencoder.

Anomaly detection has been applied in the various disease of medical practice, such as breast cancer, retinal, lung lesion, and skin disease. However, in real-world anomaly detection, there exist a large number of healthy samples, and but very few sick samples. To alleviate the problem of data imbalance in anomaly detection, this paper proposes an unsupervised learning method for deep anomaly detection based on an improved adversarial autoencoder, in which a module called chain of convolutional block (CCB) is employed instead of the conventional skip-connections used in adversarial autoencoder. Such CCB connections provide considerable advantages via direct connections, not only preserving both global and local information but also alleviating the problem of semantic disparity between the encoding features and the corresponding decoding features. The proposed method is thus able to capture the distribution of normal samples within both image space and latent vector space. By means of minimizing the reconstruction error within both spaces during training phase, higher reconstruction error during test phase is indicative of an anomaly. Our method is trained only on the healthy persons in order to learn the distribution of normal samples and can detect sick samples based on high deviation from the distribution of normality in an unsupervised way. Experimental results for multiple datasets from different fields demonstrate that the proposed method yields superior performance to state-of-the-art methods.

Tuning Surface-Electron Spins on Fe3 O4 (111) through Chemisorption of Carbon Monoxide.

The adsorption-induced flip of electron spin at interfaces is an important but poorly understood phenomenon for magnetic devices, sensors, and heterogeneous catalysis, due to the difficulties in determining the surface spins at atomic resolution. We present an evolutionary magnetic order searching method that allows efficient identification of the ground state spin configuration of magnetic bulk and surfaces. Using this approach, we have discovered for the first time a set of adsorption-induced near-degenerate surface magnetic states on the Fe3 O4 (111) surface. Molecular adsorption of CO causes a destabilization of the magnetic states of the clean surface leading to a set of near-degenerate surface magnetic states at medium coverage, which causes an abrupt increase of the magnetic entropy on the surface. The empty 2π* orbital of CO, which could accommodate the back donation of the spin density in the Fe d orbitals, plays a key role for the CO adsorption-induced spin transition.

Linkage Isomers of 4-Methylimidazolate Mn(II) Porphyrinates: Hindered or Unhindered?

Three different manganese(II) porphyrins have been exploited to react with 4-methylimidazolate (4-MeIm-), and the five-coordinate products are characterized by ultraviolet-visible, single-crystal X-ray, and electronic paramagnetic resonance spectroscopies. Interestingly, 4-MeIm- is found to bond to the metal center through either of the two N atoms (N1 or N3), which yielded two linkage isomers with either an unhindered or a hindered ligand conformation, respectively. Investigations revealed it is the large metal out-of-plane displacements (Δ24 and Δ4 ≥ 0.59 Å) that have rendered the equivalence of two isomers with a small energy difference (5.2-8.3 kJ/mol). The nonbonded intra- and intermolecular interactions thus become crucial factors in the balance of linkage isomerization. All of the products in both solution and solid states show the same characteristic resonances of high-spin Mn(II) (S = 5/2) with g⊥ ≈ 5.9 and g∥ ≈ 2.0 at 4 K, consistent with the weak effects of the axial ligand on core conformation and metal electronic configurations. Zero-field splitting parameters obtained through simulations are also reported.

Genomic characteristics and pathogenicity of a new recombinant strain of porcine reproductive and respiratory syndrome virus.

Recombination is an important phenomenon that accelerates evolution and enriches the genetic diversity of porcine reproductive and respiratory syndrome virus (PRRSV). Recombinant PRRSV isolates sometimes have different genetic backgrounds. In this study, we report a recombinant PRRSV (SD-YL1712) isolated from a pig farm. The genome of SD-YL1712 is 15,014 nucleotides in length, and its nucleotide and amino acid sequence conservation is higher than that of PRRSV strain JXA1 except within the NSP2 region. The NSP2 region of SDYL1712 shares the highest nucleotide (85.9%) and amino acid (84.1%) sequence identity with PRRSV strain NADC30. SD-YL1712 was found to contain a characteristic 131-amino-acid deletion in the NSP2 region. Two recombination breakpoints were detected at nt 2134 and nt 3958 within the NSP2 region, which revealed that SD-YL1712 originated from a recombination event between NADC30-like and HP-PRRSV-derived MLV-like strains. Interestingly, SD-YL1712 had an additional deletion at position 586, similar to that found in strain TJnh1501. Moreover, the pathogenicity of strain SD-YL1712 was found to be similar to that of HP-PRRSV JXA1, which was higher than that of the CH1a strain. Further analysis indicated that SD-YL1712 might be a transitional intermediate in the evolution of TJbd1401 to TJnh1501.

Prevalence of mental health problems in frontline healthcare workers after the first outbreak of COVID-19 in China: a cross-sectional study.

BACKGROUND: More than 210,000 medical workers have fought against the outbreak of Coronavirus Disease 2019 (COVID-19) in Hubei in China since December 2019. However, the prevalence of mental health problems in frontline medical staff after fighting COVID-19 is still unknown. METHODS: Medical workers in Wuhan and other cities in Hubei Province were invited to participate a cross-sectional and convenience sampling online survey, which assessed the prevalence of anxiety, insomnia, depression, and post-traumatic stress disorder (PTSD). RESULTS: A total of 1,091 responses (33% male and 67% female) were valid for statistical analysis. The prevalence was anxiety 53%, insomnia 79%, depression 56%, and PTSD 11%. Healthcare workers in Wuhan were more likely to face risks of anxiety (56% vs. 52%, P = 0.03) and PTSD (15% vs. 9%, P = 0.03) than those in other cities of Hubei. In terms of educational attainment, those with doctoral and masters' (D/M) degrees may experience more anxiety (median of 7.0, [interquartile range (IQR) 2.0-8.5] vs. median 5.0 [IQR 5.0-8.0], P = 0.02) and PTSD (median 26.0 [IQR 19.5-33.0] vs. median 23.0 [IQR 19.0-31.0], P = 0.04) than those with lower educational degrees. CONCLUSIONS: The mental problems were an important issue for the healthcare workers after COVID-19. Thus, an early intervention on such mental problems is necessary for healthcare workers.

First detection and phylogenetic analysis of porcine circovirus 3 in female donkeys with reproductive disorders.

BACKGROUND: PCV3 is a pathogen associated with porcine dermatitis and nephropathy syndrome (PDNS)-like clinical signs, reproductive failure, and cardiac and multiorgan inflammation, which was newly identified in 2016 in sows in USA. Recently, PCV3 has also been identified from several non-porcine species like (cattle, dog, wild boar, deer, mice and ticks). However, PCV3 infection in donkey is not well established. Since 2019, 300 blood samples were collected from female donkey, which was characterized by abortion and sterility, in Liaocheng city of China. RESULTS: In the present study, an investigation of PCV3 in donkey blood samples was undertaken employing by real time PCR. Positive rates of PCV3 in donkeys reach to 21.0 %. In addition, one full-length PCV3 genome sequence was obtained, and it had a highest identity with porcine circovirus 3 PCV3/CN/Nanjing2017 strain and is clustered to PCV3a genotype based on ORF2 sequences. CONCLUSIONS: This is the first report of detection of PCV3 from female donkeys presenting reproductive failure in large-scale donkey farms, China. In addition, the PCV3 strain identified in this study shared the closest relationship with those from porcine, suggesting that PCV3 may be transmitted from pigs to donkeys. Totally, PCV3 infection in donkey should be concerned although the association between it and reproductive failure are not better understood.

Screening and Analysis of Multiclass Veterinary Drug Residues in Animal Source Foods using UPLC-Q-Exactive Orbitrap/MS.

A rapid, simple, and sensitive method of detecting veterinary drug residues in animal food sources, including poultry and pork, was developed and validated. The method was optimized for over 155 veterinary drugs of 21 different classes. Sample pretreatment included a simple solid-liquid extraction step with 0.2% formic acid-acetonitrile-water and a purification step with a PRiME HLB (hydrophile-lipophile balance) solid-phase extraction cartridge. Data were collected using ultra-high-performance liquid chromatography coupled to Quadrupole-Exactive Orbitrap mass spectrometry. The limits of detection of 155 veterinary drugs ranged from 0.1 µg/kg to 10 µg/kg. The recovery rates were between 79.2 and 118.5 % in all matrices studied, with relative standard deviation values less than 15% (n = 6). The evaluated method allows the reliable screening, quantification, and identification of 155 veterinary drug residues in animal source food and has been successfully applied in authentic samples.

Predicted yeast interactome and network-based interpretation of transcriptionally changed genes.

Saccharomyces cerevisiae, budding yeast, is a widely used model organism and research tool in genetics studies. Many efforts have been directed at constructing a high-quality comprehensive molecular interaction network to elucidate the design logic of the gene circuitries in this classic model organism. In this work, we present the yeast interactome resource (YIR), which includes 22,238 putative functional gene interactions inferred from functional gene association data integrated from 10 databases focusing on diverse functional perspectives. These putative functional gene interactions are expected to cover 18.84% of yeast protein interactions, and 38.49% may represent protein interactions. Based on the YIR, a gene set linkage analysis (GSLA) web tool was developed to annotate the potential functional impacts of a set of transcriptionally changed genes. In a case study, we show that the YIR/GSLA system produced more extensive and concise annotations compared with widely used gene set annotation tools, including PANTHER and DAVID. Both YIR and GSLA are accessible through the website http://yeast.biomedtzc.cn.

An adult co-presented with varicella and herpes zoster caused by varicella zoster virus genotype J, China: a case report.

BACKGROUND: Varicella zoster virus (VZV) causes varicella primarily in childhood, and some rare adults also report varicella. Herpes zoster mainly occurs in adults by endogenous reactivation of latent VZV. Until now, varicella and herpes zoster have seldom been reported simultaneously in one patient. Here, we report a rare case co-presenting with varicella and herpes zoster in a Chinese adult. CASE PRESENTATION: A 44-year-old Chinese man suffered papules and vesicles with pain on the left ear. Five days after onset, he was admitted to the Department of Dermatology of The Third Hospital of Xiamen. Physical examination revealed that small vesicles surrounded by erythema had developed on his trunk, back and neck, and unilateral papules and vesicles in ribbons had also developed on the left ear. This patient was excluded from human immunodeficiency virus and Treponema pallidum infections by ELISA antibody tests. Laboratory tests revealed that the ratio of eosinophils (0.1%) and eosinophil count (0.0 × 109/L) were significantly downregulated. Treatment with valacyclovir, ebastine, mecobalamine, pregabalin and calamine lotion for 5 days was effective therapy for varicella and herpes zoster. Polymerase chain reaction for vesicular fluids from varicella and herpes zoster was positive for VZV, and further phylogenetic analysis and single nucleotide polymorphism variations confirmed that the VZV genotype was type J (clade 2). CONCLUSIONS: This rare case highlights awareness of varicella and herpes zoster caused by VZV infection in adults. Our report provides novel insight into the rare clinical presentation of VZV genotype J.

Molecular identification and characterization of Anaplasma capra and Anaplasma platys-like in Rhipicephalus microplus in Ankang, Northwest China.

BACKGROUND: Four species within Anaplasma genus are emerging zoonotic pathogens, which are transmitted by ticks and generate veterinary and public health concerns. Here, we performed a molecular survey of Anaplasma in Ankang, Northwest China. METHODS: Hard ticks were collected and identified using morphological and molecular methods. Human-pathogenic Anaplasma species were tested using nested polymerase chain reaction. The nearly complete rrs, gltA, and groEL genes sequences from revealed Anaplasma species were amplified and sequenced to determine their molecular characteristics and their phylogeny. RESULTS: All ticks collected in Ankang belonged to the Rhipicephalus microplus. Novel unclassified Anaplasma strains genetically related to A. platys and A. capra were detected in these ticks. Co-infection of these two organisms was also found. The novel unclassified Anaplasma strains identified in this study formed a distinct phylogenetic lineage based on the groEL gene and two lineages based on the gltA gene within A. platys and related strains group. The revealed A. capra strains identified in this study were most closely related to those detected in humans and other vertebrate animals. CONCLUSION: We revealed the presence of A. capra, a novel human pathogens in R. microplus ticks in previously unrecognized endemic regions. We also detected a novel unclassified Anaplasma species genetically related to A. platys. The epidemiology of anaplasmosis caused by these two Anaplasma species in humans should be assessed in future studies.

Self-referenced technology for refractive index measurement under mechanical vibration and temperature fluctuation.

A novel critical angle refractometer with self-referenced performance (SRCAR) under mechanical vibration and temperature fluctuation is presented. In a traditional CAR, mechanical vibrations and temperature fluctuations always exist and cause errors. To reduce these errors, a CAR is redesigned by introducing a reference glass with a known refractive index so that an exact calibration curve can always be determined, even though intense mechanical vibrations exist. To verify the insensitivity to these vibrations, the refractive index is monitored while the peak acceleration of the vibration is approximately 14 m/s2. The SRCAR is also used to measure a sample under different temperatures to verify the insensitivity to temperature fluctuations. Experimental measurements show that the SRCAR has the ability to lower the influences of vibrations as well as temperature fluctuations and retain a high precision of 2.5×10-4 refractive index units (RIU).

High-precision algorithms for critical angle refractive index measurement.

The critical angle method for refractive index measurement has attracted considerable attention. Precisely obtaining the critical angle is vital to the measurement process. Two advanced algorithms capable of improving the resolution of critical angle refractive index measurement systems are demonstrated. It is experimentally verified that the two algorithms improve the measurement resolution and retain linearity in the entire measurement range. The algorithm analyzes the data near the critical angle to achieve high precision, and this approach provides a notable improvement over the traditional algorithm. We perform verification experiments using liquid samples with low concentration differences, and the RI changes of these samples cannot be identified by traditional algorithms. The proposed algorithm is superior to the traditional method, which yields a resolution of less than 10-5 refractive index unit (RIU). The repeatability test shows that the uncertainty is 10-5 RIU (99.7% confidence).

Discovery of a Highly Divergent Coronavirus in the Asian House Shrew from China Illuminates the Origin of the Alphacoronaviruses.

Although shrews are one of the largest groups of mammals, little is known about their role in the evolution and transmission of viral pathogens, including coronaviruses (CoVs). We captured 266 Asian house shrews (Suncus murinus) in Jiangxi and Zhejiang Provinces, China, during 2013 to 2015. CoV RNA was detected in 24 Asian house shrews, with an overall prevalence of 9.02%. Complete viral genome sequences were successfully recovered from the RNA-positive samples. The newly discovered shrew CoV fell into four lineages reflecting their geographic origins, indicative of largely allopatric evolution. Notably, these viruses were most closely related to alphacoronaviruses but sufficiently divergent that they should be considered a novel member of the genus Alphacoronavirus, which we denote Wénchéng shrew virus (WESV). Phylogenetic analysis revealed that WESV was a highly divergent member of the alphacoronaviruses and, more dramatically, that the S gene of WESV fell in a cluster that was genetically distinct from that of known coronaviruses. The divergent position of WESV suggests that coronaviruses have a long association with Asian house shrews. In addition, the genome of WESV contains a distinct NS7 gene that exhibits no sequence similarity to genes of any known viruses. Together, these data suggest that shrews are natural reservoirs for coronaviruses and may have played an important and long-term role in CoV evolution.IMPORTANCE The subfamily Coronavirinae contains several notorious human and animal pathogens, including severe acute respiratory syndrome coronavirus, Middle East respiratory syndrome coronavirus, and porcine epidemic diarrhea virus. Because of their genetic diversity and phylogenetic relationships, it has been proposed that the alphacoronaviruses likely have their ultimate ancestry in the viruses residing in bats. Here, we describe a novel alphacoronavirus (Wénchéng shrew virus [WESV]) that was sampled from Asian house shrews in China. Notably, WESV is a highly divergent member of the alphacoronaviruses and possesses an S gene that is genetically distinct from those of all known coronaviruses. In addition, the genome of WESV contains a distinct NS7 gene that exhibits no sequence similarity to those of any known viruses. Together, these data suggest that shrews are important and longstanding hosts for coronaviruses that merit additional research and surveillance.

In situ measurement of seawater salinity with an optical refractometer based on total internal reflection method.

An optical refractive index sensor used for underway seawater salinity monitoring is proposed. Due to the empirical relation to salinity, refractive index measurement provides an alternative solution to obtain salinity of seawater. We developed a compact refractive index sensor based on total internal reflection (TIR) method. Through the repeatability and stability experiment and temperature correction, the performance of the sensor has been demonstrated experimentally. To evaluate the applicability of the sensor under real turbid sea conditions, field performance of the TIR sensor has been tested on an oceanographic cruise in the eastern of Yangtze Estuary in July 2017. The underway monitoring results show good correlation with the results provided by commercial CTD profiler.

Direct Amination of Alcohols Catalyzed by Aluminum Triflate: An Experimental and Computational Study.

Among the best-performing homogeneous catalysts for the direct amination of activated secondary alcohols with electron-poor amine derivatives, metal triflates, such as aluminum triflate, Al(OTf)3 , stand out. Herein we report the extension of this reaction to electron-rich amines and activated primary alcohols. We provide detailed insight into the structure and reactivity of the catalyst under working conditions in both nitromethane and toluene solvent, through experiment (cyclic voltammetry, conductimetry, NMR spectroscopy), and density functional theory (DFT) simulations. Competition between aniline and benzyl alcohol for Al in the two solvents explains the different reactivities. The catalyst structures predicted from the DFT calculations were validated by the experiments. Whereas a SN 1-type mechanism was found to be active in nitromethane, we propose a SN 2 mechanism in toluene to rationalize the much higher selectivity observed when using this solvent. Also, unlike what is commonly assumed in homogeneous catalysis, we show that different active species may be active instead of only one.