Methanolobus mangrovi sp. nov. and Methanolobus sediminis sp. nov, two novel methylotrophic methanogens isolated from mangrove sediments in China.

Two methylotrophic methanogens, designated strains FTZ2T and FTZ6T, were isolated from mangrove sediment sampled in Futian Mangrove Nature Reserve in Shenzhen, PR China. Cells of strains FTZ2T and FTZ6T were cocci, with diameters of 0.6-1.0 µm and 0.6-0.9 µm, respectively. Both strains grew on methanol, methylamine, dimethylamine and trimethylamine, but not on acetate, formate, H2/CO2, choline, betaine or dimethyl sulphide. Strain FTZ2T grew at 10-37 °C (optimally at 33 °C), pH 5.5-8.0 (optimally at pH 7.0) and 0-1.03 M NaCl (optimally at 0.17 M NaCl). In contrast, strain FTZ6T grew at 15-42 °C (optimally at 37 °C), pH 5.0-7.5 (optimally pH 6.5) and 0-1.03 M NaCl (optimally at 0.17 M NaCl). Both strains required magnesium for growth and were susceptible to sodium dodecyl sulphate. Biotin was required for the growth of strain FTZ2T but not of strain FTZ6T. The genomic G+C contents of strains FTZ2T and FTZ6T were 41.6 and 40.9 mol%, respectively. Phylogenetic analyses revealed that strain FTZ2T was mostly related to Methanolobus psychrotolerans YSF-03T, with 16S rRNA gene similarity of 98.6 %, an average nucleotide identity (ANI) of 82.5 %, and a digital DNA-DNA hybridization (dDDH) of 24.6 %. While strain FTZ6T was mostly related to Methanolobus vulcani PL-12/MT, with 16S rRNA gene similarity of 99.4 %, an ANI of 88.6% and a dDDH of 34.6 %. Based on phenotypic, phylogenetic and genotypic evidence, two novel species of the genus Methanolobus, Methanolobus mangrovi sp. nov. and Methanolobus sediminis sp. nov., are proposed. The type strain of M. mangrovi sp. nov. is FTZ2T (=CCAM 1276T=JCM 39396T) and the type strain of M. sediminis sp. nov. is FTZ6T (=CCAM 1277T=JCM 39397T).

Desulfovibrio mangrovi sp. nov., a sulfate-reducing bacterium isolated from mangrove sediments: a member of the proposed genus "Psychrodesulfovibrio".

"Psychrodesulfovibrio", a proposed genus within the family Desulfovibrionaceae, is a group of sulfate-reducing bacteria with biogeochemical significance but restricted child taxa availability. In this study, a strictly anaerobic bacterium, designed strain FT415T, was isolated from mangrove sediments in Futian Mangrove Nature Reserve in Shenzhen, China. The strain was Gram-stain-negative, motile, and vibrio-shaped with a single polar flagellum, which grew at the temperature range of 15-42 °C (optimum 37 °C), pH range of 6.0-7.5 (optimum 6.8), and in the presence of 0-36 g l-1 NaCl (optimum 6 g l-1 NaCl). In the presence of sulfate, electron donors including lactate, ethanol, pyruvate, malate, fumarate, succinate, cysteine, and glycerol were incompletely oxidized to acetate, and H2 and formate were used as electron donors with acetate as the carbon source by strain FT415T. Sulfate, thiosulfate, sulfide, and anthraquinone-2,6-disulfonate were reduced in the presence of lactate. Fe(III) oxide was reduced without cell growth. Fermentative growth was observed with pyruvate and cysteine. Vitamins were not required for growth. The major cellular fatty acids (> 10%) were C16:0, summed feature 10 (C18:1 c11/t9/t6 and/or unknown ECL 17.834), C16:1 cis 9, and C18:0. The major polar lipids were phosphatidylethanolamine, phospholipids, and aminolipids. The predominant menaquinone was MK-6(H2). The genomic DNA G+C content was 56.7%. Phylogenetic analysis showed that strain FT415T shared a 98.1% similarity in 16S rRNA gene sequence, an average nucleotide identity value of 84.0%, an average amino-acid identity value of 85.4%, and a digital DNA-DNA hybridization value of 25.7% with its closest relative Desulfovibrio subterraneus HN2T, which has been proposed to be transferred to the genus "Psychrodesulfovibrio". Based on phenotypic, phylogenetic, and genotypic evidence, a new species of the family Desulfovibrionaceae, Desulfovibrio mangrovi sp. nov. was proposed with the type strain FT415T (=GDMCC 1.3410T=KCTC 25525T).

Research on Crossing-Pipe Support Structure Defect Detection of EMAT-Excited CSH Wave.

A circumferential shear horizontal (CSH) guide wave-detection method using a periodic permanent magnet electromagnetic acoustic transducer (PPM EMAT) was proposed to solve the defect detection located at the inside of the pipe welded by supporting structures. Firstly, a low-frequency CSH0 mode was selected to establish a three-dimensional equivalent model for the defect detection to cross the pipe support, and the ability of the CSH0 guided wave to propagate through the support and weld structure was analyzed. Then, an experiment was used for the further exploration of the influence of different sizes and types of defects on detection after using the support, as well as the ability of detection mechanism to cross different pipe structures. The results show that both the experiment and the simulation received a good detection signal at 3 mm crack defects, which proves that the method can detect the defects by crossing the welded supporting structure. At the same time, the support structure shows a greater impact on the detection of small defects than the welded structure. The research in this paper can provide ideas for guide wave detection across the support structure in the future.

Application of Adaptive Filtering Based on Variational Mode Decomposition for High-Temperature Electromagnetic Acoustic Transducer Denoising.

In high-temperature environments, the signal-to-noise ratio (SNR) of the signal measured by electromagnetic acoustic transducers (EMAT) is low, and the signal characteristics are difficult to extract, which greatly affects their application in practical industry. Aiming at this problem, this paper proposes the least mean square adaptive filtering interpolation denoising method based on variational modal decomposition (AFIV). Firstly, the high-temperature EMAT signal was decomposed by variational modal decomposition (VMD). Then the high-frequency and low-frequency noises in the signal were filtered according to the excitation center frequency. Following the wavelet threshold denoising (WTD) for the noise component after VMD decomposition was carried out. Afterward, the noise component and signal component were connected by an adaptive filtering process to achieve further noise reduction. Finally, cubic spline interpolation was used to smooth the noise reduction curve and obtain the time information. To verify the effectiveness of the proposed method, it was applied to two kinds of ultrasonic signals from 25 to 700 °C. Compared with VMD, WTD, and empirical mode decomposition denoising, the SNR was increased by 2 times. The results show that this method can better extract the effective information of echo signals and realize the online thickness measurement at high temperature.

Correlation of Key Physiological Properties of Methanosarcina Isolates with Environment of Origin.

It is known that the physiology of Methanosarcina species can differ significantly, but the ecological impact of these differences is unclear. We recovered two strains of Methanosarcina from two different ecosystems with a similar enrichment and isolation method. Both strains had the same ability to metabolize organic substrates and participate in direct interspecies electron transfer but also had major physiological differences. Strain DH-1, which was isolated from an anaerobic digester, used H2 as an electron donor. Genome analysis indicated that it lacks an Rnf complex and conserves energy from acetate metabolism via intracellular H2 cycling. In contrast, strain DH-2, a subsurface isolate, lacks hydrogenases required for H2 uptake and cycling and has an Rnf complex for energy conservation when growing on acetate. Further analysis of the genomes of previously described isolates, as well as phylogenetic and metagenomic data on uncultured Methanosarcina in anaerobic digesters and diverse soils and sediments, revealed a physiological dichotomy that corresponded with environment of origin. The physiology of type I Methanosarcina revolves around H2 production and consumption. In contrast, type II Methanosarcina species eschew H2 and have genes for an Rnf complex and the multiheme, membrane-bound c-type cytochrome MmcA, shown to be essential for extracellular electron transfer. The distribution of Methanosarcina species in diverse environments suggests that the type I H2-based physiology is well suited for high-energy environments, like anaerobic digesters, whereas type II Rnf/cytochrome-based physiology is an adaptation to the slower, steady-state carbon and electron fluxes common in organic-poor anaerobic soils and sediments. IMPORTANCE Biogenic methane is a significant greenhouse gas, and the conversion of organic wastes to methane is an important bioenergy process. Methanosarcina species play an important role in methane production in many methanogenic soils and sediments as well as anaerobic waste digesters. The studies reported here emphasize that the genus Methanosarcina is composed of two physiologically distinct groups. This is important to recognize when interpreting the role of Methanosarcina in methanogenic environments, especially regarding H2 metabolism. Furthermore, the finding that type I Methanosarcina species predominate in environments with high rates of carbon and electron flux and that type II Methanosarcina species predominate in lower-energy environments suggests that evaluating the relative abundance of type I and type II Methanosarcina may provide further insights into rates of carbon and electron flux in methanogenic environments.

LINC01116 regulates proliferation, migration, and apoptosis of keloid fibroblasts by the TGF-ß1/SMAD3 signaling via targeting miR-3141.

BACKGROUND: Keloids are benign fibroproliferative skin tumors. Long non-coding RNAs (lncRNAs) have been implicated in the pathogenesis of keloid formation. In this paper, we explored the precise actions of LINC01116 in keloid formation. METHODS: The targeted relationship between microRNA (miR)-3141 and LINC01116 or transforming growth factor ß1 (TGF-ß1) was verified by dual-luciferase reporter, RNA immunoprecipitation (RIP), and RNA pull-down assays. The expression levels of LINC01116, miR-3141, TGF-ß1, and SMAD family member 3 (SMAD3) were gauged by quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot. Cell proliferation, migration, and apoptosis were assessed by the Cell Counting Kit-8 (CCK-8) assay, wound-healing assay, and flow cytometry, respectively. Animal studies were used to assess the role of LINC01116 in the subcutaneous keloid growth in vivo. RESULTS: Our data showed that LINC01116 targeted miR-3141 by directly binding to miR-3141. LINC01116 was up-regulated and miR-3141 was down-regulated in human keloid tissues and fibroblasts. LINC01116 knockdown or miR-3141 overexpression suppressed keloid fibroblast proliferation, migration, and promoted cell apoptosis. Moreover, miR-3141 was a downstream mediator of LINC01116 function. MiR-3141 regulated the TGF-ß1/SMAD3 signaling by directly targeting TGF-ß1. Furthermore, TGF-ß1 was identified as a direct and functional target of miR-3141. LINC01116 regulated the TGF-ß1/SMAD3 signaling through miR-3141. Additionally, LINC01116 knockdown diminished the subcutaneous keloid growth in vivo. CONCLUSION: Our findings demonstrated a novel mechanism, the miR-3141/TGF-ß1/SMAD3 regulatory pathway, at least partially for the oncogenic role of LINC01116 in keloid formation.

Ni/Ni3Al interface-dominated nanoindentation deformation and pop-in events.

Nickel-based single crystal alloys have excellent mechanical properties due to its unique two-phase structure and interface. Therefore, molecular dynamics methods were used to simulate nanoindentation and microstructural evolution. We found the indenter reaction force and hardness of the Ni3Al phase is the largest. The pop-in event in Ni3Al phase is more obvious than that in the Ni phase and Ni/Ni3Al phase. Because lots of dislocations in the Ni3Al phase break through the barrier of the interface and cut into the Ni phase, while dislocations in the Ni phase only slip inside the Ni phase. Moreover, we found that the position of the starting point of the adhesion force recovery is mainly related to the elastic recovery of the material. The stronger the elastic recovery of the phase, the smaller the depth value corresponding to the starting point of the recovery. We further studied the variation of potential energy with indentation depth and found that the change of wave trough of the load-displacement (P-h) curve is related to stacking fault energy. This study has important theoretical guiding significance for the in-depth understanding and engineering application of the mechanical properties of nickel-based single crystal alloys.

Prophages contribute to genome plasticity of Klebsiella pneumoniae and may involve the chromosomal integration of ARGs in CG258.

Klebsiella pneumoniae is an important multidrug-resistant pathogen carrying prophages. Here we explore the contribution of prophages to bacterial evolution and fitness in silico. This study showed prophages contribute to remarkable genome plasticity of K. pneumoniae. The strains of CG258 possess several conserved prophages including the couple of P2-P4 prophages. CRISPR-Cas system has limited impact on the presence of prophages. The strong MLST-depended distribution of CRISPR-Cas and prophages and the high proportion of strains with self-targeting spacers may be the causes. Four core ARGs (blaSHV, fosA and oqxAB) were detected on almost all the chromosomes, but the acquired ARGs were only found in CG258 and CRISPR-positive strains. The factors influencing the chromosomal integration of ARGs in CG258 and CRISPR-positive strains may be different. In CG258, prophages may involve the chromosomal integration of ARGs. For CRISPR-positive strains, the immunity of CRISPR-Cas systems against invading ARG-bearing mobile genetic elements may accelerate the process.

BaF2TeF2(OH)2: A UV Nonlinear Optical Fluorotellurite Material Designed by Band-Gap Engineering.

Balancing the wide band gap, large second harmonic generation (SHG) response, and moderate birefringence are significant but addressable challenges for designing nonlinear optical (NLO) materials. Based on the band-gap engineering in perovskite solar cell materials, we have successfully synthesized a new fluorotellurite, BaF2TeF2(OH)2, which exhibits a pseudo-Aurivillius structure and crystallizes in a noncentrosymmetric and polar space group Pmn21. The physical property measurements show that this material can effectively balance the requirements among the short UV absorption edge (∼205 nm), large SHG response (∼3 × KDP) and moderate birefringence (∼0.078@350-700 nm) and is a promising ultraviolet NLO crystal.

Sequential fed-batch fermentation of 1,3-propanediol from glycerol by Clostridium butyricum DL07.

The demand for 1,3-propanediol (1,3-PDO) has increased sharply due to its role as a monomer for the synthesis of polytrimethylene terephthalate (PTT). Although Clostridium butyricum is considered to be one of the most promising bioproducers for 1,3-PDO, its low productivity hinders its application on industrial scale because of the longer time needed for anaerobic cultivation. In this study, an excellent C. butyricum (DL07) strain was obtained with high-level titer and productivity of 1,3-PDO, i.e., 104.8 g/L and 3.38 g/(L•h) vs. 94.2 g/L and 3.04 g/(L•h) using pure or crude glycerol as substrate in fed-batch fermentation, respectively. Furthermore, a novel sequential fed-batch fermentation was investigated, in which the next bioreactor was inoculated by C. butyricum DL07 cells growing at exponential phase in the prior bioreactor. It could run steadily for at least eight cycles. The average concentration of 1,3-PDO in eight cycles was 85 g/L with the average productivity of 3.1 g/(L•h). The sequential fed-batch fermentation could achieve semi-continuous production of 1,3-PDO with higher productivity than repeated fed-batch fermentation and would greatly contribute to the industrial production of 1,3-PDO by C. butyricum. KEY POINTS: • A novel C. butyricum strain was screened to produce 104.8 g/L 1,3-PDO from glycerol. • Corn steep liquor powder was used as a cheap nitrogen source for 1,3-PDO production. • A sequential fed-batch fermentation process was established for 1,3-PDO production. • An automatic glycerol feeding strategy was applied in the production of 1,3-PDO.

A Method for Detecting the Randomness of Barkhausen Noise in a Material Fatigue Test Using Sensitivity and Uncertainty Analysis.

The magnetic Barkhausen noise (MBN) signal provides interesting clues about the evolution of microstructure of the magnetic material (internal stresses, level of degradation, etc.). This makes it widely used in non-destructive evaluation of ferromagnetic materials. Although researchers have made great effort to explore the intrinsic random characteristics and stable features of MBN signals, they have failed to provide a deterministic definition of the stochastic quality of the MBN signals. Because many features are not reproducible, there is no quantitative description for the stochastic nature of MBN, and no uniform standards to evaluate performance of features. We aim to make further study on the stochastic characteristics of MBN signal and transform it into the quantification of signal uncertainty and sensitivity, to solve the above problems for fatigue state prediction. In the case of parameter uncertainty in the prediction model, a prior approximation method was proposed. Thus, there are two distinct sources of uncertainty: feature(observation) uncertainty and model uncertainty were discussed. We define feature uncertainty from the perspective of a probability distribution using a confidence interval sensitivity analysis, and uniformly quantize and re-parameterize the feature matrix from the feature probability distribution space. We also incorporate informed priors into the estimation process by optimizing the Kullback-Leibler divergence between prior and posterior distribution, approximating the prior to the posterior. Thus, in an insufficient data situation, informed priors can improve prediction accuracy. Experiments prove that our proposed confidence interval sensitivity analysis to capture feature uncertainty has the potential to determine the instability in MBN signals quantitatively and reduce the dispersion of features, so that all features can produce positive additive effects. The false prediction rate can be reduced to almost 0. The proposed priors can not only measure model parameter uncertainties but also show superior performance similar to that of maximum likelihood estimation (MLE). The results also show that improvements in parameter uncertainties cannot be directly propagated to improve prediction uncertainties.

CsZn2 BO3 X2 (X2 =F2 , Cl2 , and FCl): A Series of Beryllium-Free Deep-Ultraviolet Nonlinear-Optical Crystals with Excellent Properties.

Designing deep-ultraviolet (DUV) nonlinear-optical (NLO) crystals is one of the major current research interests, but it faces a great challenge. In order to overcome the problem of crystal growth and the toxicity of BeO raw materials in KBe2 BO3 F2 (KBBF), the only applicable DUV NLO crystal so far, we substitute Be2+ cations with Zn2+ in the KBBF structure and modify the halogen anions, by which three new Zn-containing KBBF-like compounds, CsZn2 BO3 X2 (X2 =F2 , Cl2 , and FCl), have been successfully synthesized. They all exhibit excellent NLO properties, including improved SHG responses (2.8-3.5×KDP) and short UV cut-off edges (<190 nm). In comparison with KBBF, CsZn2 BO3 X2 (X2 =F2 , Cl2 , and FCl) are all chemically benign and have better growth habits, so they are all promising as DUV NLO crystals. Further study on structure-property relationships indicates that the mixing of halogen anions is a feasible strategy to enhance the SHG responses of the KBBF family.

Efficient Genome Engineering of a Virulent Klebsiella Bacteriophage Using CRISPR-Cas9.

Klebsiella pneumoniae is one of the most common nosocomial opportunistic pathogens and usually exhibits multiple-drug resistance. Phage therapy, a potential therapeutic to replace or supplement antibiotics, has attracted much attention. However, very few Klebsiella phages have been well characterized because of the lack of efficient genome-editing tools. Here, Cas9 from Streptococcus pyogenes and a single guide RNA (sgRNA) were used to modify a virulent Klebsiella bacteriophage, phiKpS2. We first evaluated the distribution of sgRNA activity in phages and proved that it is largely inconsistent with the predicted activity from current models trained on eukaryotic cell data sets. A simple CRISPR-based phage genome-editing procedure was developed based on the discovery that homologous arms as short as 30 to 60 bp were sufficient to introduce point mutation, gene deletion, and swap. We also demonstrated that weak sgRNAs could be used for precise phage genome editing but failed to select random recombinants, possibly because inefficient cleavage can be tolerated through continuous repair by homologous recombination with the uncut genomes. Small frameshift deletion was proved to be an efficient way to evaluate the essentiality of phage genes. By using the abovementioned strategies, a putative promoter and nine genes of phiKpS2 were successfully deleted. Interestingly, the holin gene can be deleted with little effect on phiKpS2 infection, but the reason is not yet clear. This study established an efficient, time-saving, and cost-effective procedure for phage genome editing, which is expected to significantly promote the development of bacteriophage therapy.IMPORTANCE In the present study, we have addressed efficient, time-saving, and cost-effective CRISPR-based phage genome editing of Klebsiella phage, which has the potential to significantly expand our knowledge of phage-host interactions and to promote applications of phage therapy. The distribution of sgRNA activity was first evaluated in phages. Short homologous arms were proven to be enough to introduce point mutation, small frameshift deletion, gene deletion, and swap into phages, and weak sgRNAs were proven useful for precise phage genome editing but failed to select random recombinants, all of which makes the CRISPR-based phage genome-editing method easier to use.

Broadband Linear High-Power Amplifier Based on the Parallel Amplification Architecture for Electromagnetic Ultrasonic Guided Wave.

The linear power amplifier with high-output power in the broadband frequency is the critical component required by exciting the electromagnetic acoustic transducer (EMAT) to generate ultrasonic guided wave (UGW). The methods to realize the output of a high-power signal in the linear amplification mode and to expand the bandwidth at high-output power are seldom reported. To solve these problems, a power amplifier with differential structure is developed by using the parallel amplification architecture and the broadband feedback circuits. The proposed power amplifier uses a differential structure to suppress the even harmonic waves and remove the disruptions. Each branch of the differential structure consists of five linear power amplifier modules with output terminals connected in parallel to increase the output power. Also, the negative voltage feedback is used to extend the bandwidth of the power amplifier. The experimental results show that the -3 dB bandwidth of the amplifier is from 40 kHz to 2.5 MHz, and the transient output power is greater than 1 kW. The power amplifier can drive the EMATs to generate ultrasonic guided waves. Because of the high-output power and good linearity, the proposed power amplifier has excellent potential for EMAT UGW applications.

A New Fuzzy Logic Classifier Based on Multiscale Permutation Entropy and Its Application in Bearing Fault Diagnosis.

The self-organizing fuzzy (SOF) logic classifier is an efficient and non-parametric classifier. Its classification process is divided into an offline training stage, an online training stage, and a testing stage. Representative samples of different categories are obtained through the first two stages, and these representative samples are called prototypes. However, in the testing stage, the classification of testing samples is completely dependent on the prototype with the maximum similarity, without considering the influence of other prototypes on the classification decision of testing samples. Aiming at the testing stage, this paper proposed a new SOF classifier based on the harmonic mean difference (HMDSOF). In the testing stage of HMDSOF, firstly, each prototype was sorted in descending order according to the similarity between each prototype in the same category and the testing sample. Secondly, multiple local mean vectors of the prototypes after sorting were calculated. Finally, the testing sample was classified into the category with the smallest harmonic mean difference. Based on the above new method, in this paper, the multiscale permutation entropy (MPE) was used to extract fault features, linear discriminant analysis (LDA) was used to reduce the dimension of fault features, and the proposed HMDSOF was further used to classify the features. At the end of this paper, the proposed fault diagnosis method was applied to the diagnosis examples of two groups of different rolling bearings. The results verify the superiority and generalization of the proposed fault diagnosis method.

Stability and oscillatory behavior of microbial consortium in continuous conversion of crude glycerol to 1,3-propanediol.

Microbial consortium is an alternative for bioconversion of crude glycerol to value-added products whereas concerns about the process stability in long-term operation existed. The aim of this study is to evaluate the feasibility of using an anaerobic microbial consortium as inoculum for continuous conversion of crude glycerol to 1,3-propanediol (1,3-PDO). Performances of continuous fermentations with the consortium inoculum were evaluated under different dilution rates and glycerol feed concentrations. The highest 1,3-PDO production of 57.86 g/L was achieved with a productivity of 5.55 g/(L·h). Analyses of kinetic data showed that the consortium maintained a consistent pattern for 1,3-PDO production under different operating conditions despite changes in community composition. The continuous fermentation by the consortium was able to operate for a longer period of time (31 volume changes) than that using pure culture (24 volume changes) with the average 1,3-PDO concentration of 53.52 g/L and productivity of 6.69 g/(L·h) under glycerol-excess condition, which could be contributed to the intraspecies diversity among Clostridium butyricum in the consortium. Under glycerol-limited conditions, however, a spontaneous oscillation of the consortium was observed after continuous operation for about 120 h, along with severe fluctuations of the microbial community. The oscillatory behavior could be reduced by increasing the dilution rates and was likely the metabolic feature of C. butyricum.

Selection and characterization of an anaerobic microbial consortium with high adaptation to crude glycerol for 1,3-propanediol production.

Crude glycerol is an ideal feedstock for bioproduction of 1,3-propanediol (1,3-PDO) while pure culture always shows low substrate tolerance and limited productivity. In this study, an anaerobic microbial consortium for conversion of crude glycerol was selected and its 1,3-PDO production capacity was evaluated. The consortium was obtained from anaerobic activated sludge by 19 serial transfers and mainly consisted of 94.64% Clostridiaceae and 4.47% Peptostreptococcaceae. The consortium adapted well with high glycerol concentration of 120 g/L as well as wide substrate concentration fluctuation from 15 to 80 g/L, producing 60.61 and 82.66 g/L 1,3-PDO in the batch and fed-batch fermentation, with the productivity of 3.79 and 3.06 g/(L∙h), respectively, which are among the best results published so far. Furthermore, mini consortia isolated by serial dilution exhibited similar microbial composition but gradually decreasing tolerance to crude glycerol. Four randomly selected Clostridium butyricum displayed different substrate tolerance and insufficient 1,3-PDO production capacity. This work demonstrated that the high adaptation to crude glycerol of the consortium was the collaborative effort of different individuals.

Molecular dynamics study of the trans-grain extension behavior of crack tips under synergistic effects.

In this paper, the trans-grain extension behavior of crack tips is investigated. The crack propagation mechanism of BCC-Fe model of single and combination orientation under type I loading was studied by molecular dynamics method. It is found that crystal orientation has an important effect on the activation and evolution of crack growth. The propagation mechanism of each orientation in the combination model works together to control the propagation behavior of the crack. The results show that the combination of brittle cleavage and grains with weak ductility exhibits better ductility expansion. For the combination of strong ductility and weak ductility, the ductility behavior decreases, which will seriously harm engineering safety. The limiting effect of combination orientation can enhance the toughness of crack propagation. Stress concentration and shear bands are easy to form along the single layer twin, and the formation of slip bands in the weak toughness orientation reduces the crack propagation toughness behavior of the combined model.

Development of a Meander-Coil-Type Dual Magnetic Group Circumferential Magnetostrictive Guided Wave Transducer for Detecting Small Defects Hidden behind Support Structures.

In order to solve the problem that small defects hidden behind pipeline support parts are difficult to detect effectively in small spaces, such as offshore oil platforms, a meander-coil-type dual magnetic group circumferential magnetostrictive guided wave transducer is developed in this paper. The transducer, which consists of a coil, two sets of permanent magnets, and a magnetostrictive patch, can excite a high-frequency circumferential shear horizontal (CSH) guided wave. The energy conversion efficiency of the MPT is optimized through magnetic field simulation and experiment, and the amplitude of the defect signal is enhanced 1.9 times. The experimental results show that the MPT developed in this paper can effectively excite and receive CSH2 mode guided waves with a center frequency of 1.6 MHz. Compared with the traditional PPM EMAT transducer, the excitation energy of the transducer is significantly enhanced, and the defects of the 2 mm round hole at the back of the support can be effectively detected.

Effect of Filling Material Properties on 1-3 Piezoelectric Composite Performance.

The 1-3 piezoelectric composite is the key component of the acoustic transducer, which is widely used in detection, due to the high energy conversion efficiency, cheap raw material, and low aging. To reveal the influence of epoxy mixture, used to connect the piezoelectric column, on the composite performance, a 1-3 piezoelectric composite model was built. The effects of mixture properties on the impedance curves, vibration mode, and deformation displacement of the composite were determined. Six 1-3 piezoelectric composites with different filling mixture properties, by changing the glass microspheres' mass ratio in the epoxy, were prepared and measured to validate the model. The results showed that with the increase in the proportion of the glass microsphere in the epoxy mixture, the vibration coupling of the piezoelectric composites was gradually eliminated. The acoustic impedance was reduced by 12%. The electromechanical coupling coefficient and effective electromechanical coupling coefficient were increased by 5.4% and 8.3%, respectively. The density and Young's modulus decrease in filling mixture can significantly improve piezoelectric composite performance.