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Frequency-domain synthetic aperture focusing technique (SAFT), such as non-stationary phase shift migration (NSPSM), plays an essential role in the ultrasonic imaging of two-layered systems with non-planar interfaces. However, with NSPSM fast imaging under blind test conditions is hard to realize due to a lack of interface information in practice. To overcome this difficulty, a fast interface reconstruction method for NSPSM imaging of non-planar two-layered systems is proposed based on virtual points measuring. In blind testing conditions, a series of virtual points (VP) were created at the non-planar interface of the two-layered system by the time-of-flight (TOF) of the first incoming echo. Then, the interface for the two-layered system was quickly established by the interpolation of the VP. Finally, the NSPSM imaging for the two-layered system with non-planar interfaces was realized by the borderline which is used to distinguish the velocities of the coupling medium and tested part in the same extrapolating depth. The imaging results showed that the position of side-drilled holes was located correctly and the efficiency of the algorithm was significantly improved. Hence, the VP-NSPSM method is expected to achieve fast or even real-time imaging of two-layered systems with non-planar interfaces in practical NDT applications.

Additional file 4. Volcano plot displaying differential expressed genes in bovine liver at different lactation stages.

Additional file 3. Correlation analysis of the reads.

Additional file 2. Summary of sequence read alignments to the reference genome.

Additional file 1. The basic statistics for RNA-seq reads generated from liver tissues of three cows at different lactation stages.

Anthocyanin is a flavonoid compound with potential antioxidant properties beneficial to human health and sustains plant growth and development under different environmental stresses. In black rice, anthocyanin can be found in the stems, leaves, stigmas, and caryopsis. Although the anthocyanin biosynthesis in rice has been extensively studied, limited knowledge underlying the storage mechanism and transporters is available. This study undertook the complementation of computational and transcriptome analysis to decipher a potential multidrug and toxic compound extrusion (MATE) gene candidate for anthocyanin transportation in black rice caryopsis. The phylogenetic analysis showed that OsMATE34 has the same evolutionary history and high similarities with VvAM1, VvAM3, MtMATE2, SlMATE/MTP77, RsMATE8, AtFFT, and AtTT12 involved in anthocyanin transportation. RNA sequencing analysis in black caryopsis (Bc, Bc11, Bc18, Bc25) and white caryopsis (Wc, Wc11, Wc18, Wc25), respectively, at 11 days after flowering (DAF), 18 DAF, and 25 DAF revealed a total of 36,079 expressed genes, including 33,157 known genes and 2922 new genes. The differentially expressed genes (DEGs) showed 15,573 genes commonly expressed, with 1804 and 1412 genes uniquely expressed in Bc and Wc, respectively. Pairwise comparisons showed 821 uniquely expressed genes out of 15,272 DEGs for Wc11 vs. Bc11, 201 uniquely expressed genes out of 16,240 DEGs for Wc18 vs. Bc18, and 2263 uniquely expressed genes out of 16,240 DEGs for Wc25 vs. Bc25. Along with anthocyanin biosynthesis genes (OsPAL, OsCHS, OsCHI, OsF3H, OsDFR, OsANS, and OsUFGT/Os3GT), OsMATE34 expression was significantly upregulated in all Bc but not in Wc. OsMATE34 expression was similar to OsGSTU34, a transporter of anthocyanin in rice leaves. Taken together, our results highlighted OsMATE34 (Os08g0562800) as a candidate anthocyanin transporter in rice caryopsis. This study provides a new finding and a clue to enhance the accumulation of anthocyanin in rice caryopsis.

In order to overcome the limitations of traditional ultrasonic imaging methods, which cannot directly give the imaging results of defects in a pipeline and have low imaging quality, a frequency domain synthetic aperture focusing pipeline imaging method based on phase migration is proposed. The measured data were reconstructed by frequency domain synthetic aperture focusing, and the results were compared with those of time-domain synthetic aperture focusing imaging. The results show that the frequency domain synthetic aperture imaging method is more accurate for the location and quantification of defects in a pipeline, the influence of noise waves on the imaging transverse resolution is reduced, and the imaging resolution is increased by nearly 30%. It was found that the quantitative errors of axial double defects are 5.2% and 17.9%, and that of circumferential defects is 7.5%. These results show that the frequency domain synthetic aperture focusing pipeline imaging algorithm based on phase migration can achieve the accurate determination of multiple defects in pipelines.

The design of a freestanding electrode is the key to the development of energy storage devices with superior electrochemical performance and mechanical durability. Herein, we propose a highly-scalable strategy for the facile synthesis of a freestanding alluaudite Na2+2xFe2−x(SO4)3@porous carbon-nanofiber hybrid film, which is used as a self-supported and flexible electrode for sodium ion batteries. By the combined use of electrospinning and electrospraying, the freestanding hybrid film is constructed in the form of sulfate nanoparticles enwrapped in highly porous graphitic-like carbon-nanofibers. The multimodal porous architecture of the freestanding hybrid film ensures its superiority in mechanical flexibility and structural stability during repeated electrochemical processes, which meets the long-standing challenge of practical application. Moreover, both the highly conductive and porous framework and the nanoscale particles are favorable for promoting fast electron/ion transport capability. Compared with other carbon based supports such as graphene (GA), carbon nanotubes (CNTs) and active carbons (ACs), the flexible carbon nanofiber shows better interaction with electrochemical active materials and superior electrochemical properties. It retains over 95% of the capacity after five hundred cycles at alternate rates of 40C and 5C, which demonstrates the superior ultralong time and high-rate cycling capability. Therefore, the present work provides a facile and highly scalable strategy for the design and fabrication of high-performance freestanding sulfate cathodes for advanced sodium ion batteries.

The correlations between properties and architecture are a central theme for electroactive materials in energy storage devices. We have conducted a systematic investigation on the relationship between the architecture and physicochemical characteristics of sulfate/C composites. Three types of carbon matrix, i.e. activated carbon (AC:0D), single wall carbon nanotubes (CNT:1D) and graphene (GA:2D) were employed to construct different structured sulfate/C composites. The discussion is focused on the relationship between the architecture and properties such as electronic conductivity, moisture absorption, sodium intercalation kinetics and the electrochemical performance of the sulfate/C composite. The Na2Fe(SO4)2·2H2O/AC composite has the largest electrode/electrolyte interface and the highest porosity, thus it allows the fastest ionic diffusion and the best high-rate capability. However, the sandwich-type Na2Fe(SO4)2·2H2O/GA composite has the most compact and toughest architecture, thus it allows the highest electronic conductivity and the lowest moisture sensitivity. The rational design principle for the Na2Fe(SO4)2·2H2O/C composite with desirable thermodynamic and kinetic characteristics was deduced from a comprehensive evaluation of the architecture–property relationships. We also propose the electron/ion diffusion pathway and moisture absorption mechanism found for the different architectures. The present study has potential application as a design guide for Na2Fe(SO4)2·2H2O/C composites in energy storage and conversion.

High potential sodium hosts have attracted enormous attention recently in view of the requirement for improving energy density for sodium ion batteries. Na7V4(P2O7)4(PO4) and Na7V3(P2O7)4 with operating potentials near 4.0 V versus Na+/Na are promising cathode candidates. But the low conductivity, limited ion intercalation kinetics and inferior stability remain critical drawbacks for their practical applications. In this paper, the design of freestanding three-dimensional (3D) hybrid foams of high potential sodium hosts@biomass-derived porous carbon is reported. The biological fungus realizes the formation of highly porous graphene-like carbon, which constructs the 3D framework for the high potential polyanions. The polyanion nanocrystals are closely enwrapped by the biomass derived framework and build the hybrid architecture. Both the highly conductive skeleton and the hierarchically porous architecture of hybrid foams are favourable for highly efficient electron and ion transport. Furthermore, the depressed structural deterioration rate and improved contact between the active material and conductive substrate are achieved for the 3D hybrid foams in comparison with the conventional electrodes on the basis of the dynamic studies. Without additional additive or binders, the freestanding hybrid foams achieve desirable characteristics of high operating potentials, fast sodium intercalation and excellent cycling stability. The Na7V4(P2O7)4(PO4)- and Na7V3(P2O7)4-based hybrid foams retain 94% and 91%, respectively, of the capacities after 800 cycles at alternative 20C and 3C, demonstrating their superior high rate ultra long-term cycling capability. Therefore, this research provides a low-cost, highly efficient and widely applicable architecture to construct high potential and ultra long-life cathodes for sodium batteries.

Purpose: To investigate the causes and the nursing interventions of vasovagal syncope (VVS) during ultrasound-guided Modified Seldinger Technique (MST) PICC catheterization. Methods: Clinical data (medical records, demographic data, diagnosis, local vascular compression situation, B-mode ultrasound-recorded catheter/vessel ratio and the occurrence time, symptoms and treatment of syncope) of 14 patients diagnosed as vasovagal syncope during ultrasound-guided PICC catheterization at three hospitals in Guangdong province from September 2018 to September 2019 were collected for this retrospective analysis. Results: There were 3091 cases of ultrasound-guided MST PICC catheterization in the venous catheter outpatient clinics of the 3 hospitals from September 2018 to October 2019 with 14 cases (0.45%) of intraoperative vasovagal syncope, all cancer patients (5 males, 9 females) with a mean age 45± 3.8. They all received PICC for the first time and were under mental stress during the operation. Among the 14 patients (2 mild, 7 moderate, 5 severe), 8 had multiple lymphadenectasis in the neck and clavicular areas of the catheterization side, which resulted in different degree of venous compression and difficulty in insertion; 5 had catheter/vessel ratio over 45%. 2 cases of VVS occurred when the patients were asked to turn their heads against shoulders on to the puncture side; 10 occurred when using B-mode ultrasound probe to examine the jugular vein; 2 occurred when pulling out the catheter sheath. Conclusion: The related factors of vasovagal syncope during ultrasound-guided PICC catheterization include overcompression and avulsion on blood vessels and mental stress. Therefore, it is recommended to implement psychological interventions before surgery, reduce compression and avulsion of the vascular access during catheterization, and improve practitioners’ abilities in vessel selection (vessels with a catheter/vessel ratio less than 45%) and catheterization skills to eliminate the incidence of vasovagal syncope during PICC catheterization.

At the end of 2019, an ongoing outbreak of novel Corona Virus Disease 2019 (COVID-19) was first found in Wuhan, China with a sign of person-to-person transmission and city-to-city transmission, and has spread globally. At present, the COVID-19 mortality rate in China is 2.3%, while the SARS was 9.6% and the MERS was 34.4%, reported by WHO. China improved the surveillance network when the outbreak occurred and the labs promptly identified and shared the coronavirus genome that has served greatly to effective epidemic control. Given the fact that the number of infections in China is gradually declining while that outside of China keeps rising, more comprehensive information about the features, origin, epidemiology, clinical spectrum of COVID-19 is to be identified by further studies. The analysis of Chinese WHO-affirmed effective prevention and control strategies will help China and the rest of the world better contain this outbreak and end it as soon as possible. At present, effective prevention measures for COVID-19 include isolating the infectious agents, curbing the route of transmission, conducting health education to citizens, making fewer trips outside, washing hands frequently, wearing masks, protecting eyes, showing more understanding and consolation to patients, especially to elderly patients, providing mental support for medical staff and employing y psychological intervention timely.

Glass fiber-reinforced plastics (GFRP) is widely used in many industrial fields. When acoustic emission (AE) technology is applied for dynamic monitoring, the interfering signals often affect the damage evaluation results, which significantly influences industrial production safety. In this work, an effective intelligent recognition method for AE signals from the GFRP damage is proposed. Firstly, the wavelet packet analysis method is used to study the characteristic difference in frequency domain between the interfering and AE signals, which can be characterized by feature vector. Then, the model of back-propagation neural network (BPNN) is constructed. The number of nodes in the input layer is determined according to the feature vector, and the feature vectors from different types of signals are input into the BPNN for training. Finally, the wavelet packet feature vectors of the signals collected from the experiment are input into the trained BPNN for intelligent recognition. The accuracy rate of the proposed method reaches to 97.5%, which implies that the proposed method can be used for dynamic and accurate monitoring of GFRP structures.

Rechargeable lithium-iodine batteries with abundant raw materials and low cost are promising electrochemical energy storage systems. Herein, we demonstrate that anchoring iodine to N-doped hollow carbon fold-hemisphere (N-FHS) is highly efficient to overcome slow kinetics and low stability of iodine cathode in lithium-iodine batteries. For the first time, significant effects of carbon framework architecture on the lithium storage performance of iodine cathode are studied in detail. Notably, the fold-hemisphere (N-FHS) is more effective than the similar architectures, such as hollow sphere (N-S) or hemisphere (N-HS), in modifying slow ion transport capability and fast structure deterioration. The superior property of iodine@N-FHS is associated with its highly porous structure and strong interconnection to iodine. The iodine deterioration mechanism in lithium-iodine battery is analyzed, and the deterioration processes of iodine in different carbon frameworks during cycling are investigated. This work opens a new avenue to solve the key problems in lithium-iodine batteries, allowing it an important candidate for energy storage.

The curing process of epoxy resin was monitored real-time by using embedded fiber Bragg grating (FBG) sensor. The resin was cured at room temperature 24°C for 24 hours. The curing monitor test showed that the temperature inside the resin went up quickly at the first 70 minutes. Then the temperature increased slowly till 120 minutes. Afterward, the central wavelength decreased which indicated two stage of curing, i.e. temperature reduction and curing shrinkage. Furthermore, the cured resin sample under tensile load was studied. Strain gauges were applied in order to evaluate the FBG sensor. Experimental results showed that difference existed between the mentioned sensors.

In this paper, we present automatic classification models for ultrasonic flaw signals acquired from carbon-fiber-reinforced polymer specimens. Different state-of-the-art strategies based on wavelet transform are utilized for feature extraction. Furthermore, a wavelet packet transform-based local energy feature extraction method is proposed to solve the deficiencies of the existing methods. Artificial neural networks and support vector machines are trained to validate the effectiveness of different feature extraction methods for flaw signal classification. Experimental results show that the proposed method can extract reliable features to effectively classify the different ultrasonic flaw signals with high accuracy.

Fiber Bragg grating (FBG) sensors were attractive in various fields for structural health monitoring. Because of their accurate performance and real time response, embedded FBG sensors are promising for strain monitoring in composite materials. As an optical fiber sensor was embedded inside a composite, interface would form around the embedded optical fiber and the host polymer composite. In order to study the influence of the embedded optical fiber to the mechanical character, finite elemental analysis was applied to study the stress distribution inside the composite. Keeping the resin rich area the same size, laminates with optical fibers in different diameters, which were 250 and 125 micrometers, were analyzed. The simulation results represent that stress singularity would occur around the embedded optical fiber. The singularity value for the laminate with optical fiber at 250 micrometer was higher than that with optical fiber at 125 micrometer. Micro- cracks would arise at the stress singularity point. Therefore, the optical fiber in smaller diameter was preferred since the mechanical strength could be higher. Four points bending test was carried out on a steel beam with a small-diameter FBG on the bottom surface. Besides, a strain gauge was stuck on bottom to validate the monitoring results by FBG sensor. The tested results indicated that the strain monitoring results by the small-diameter FBG sensor almost identical with the theoretical ones and what recorded by strain gauge. The maximum testing error for the designed FBG is less than 2% compared with the theoretical one.

The design of a freestanding electrode is the key to the development of energy storage devices with superior electrochemical performance and mechanical durability. Herein, we propose a highly-scalable strategy for the facile synthesis of a freestanding alluaudite Na

Biochemistry-directed synthesis of functional nanomaterials has attracted great interest in energy storage, catalysis and other applications. The unique ability of biological systems to guide molecule self-assembling facilitates the construction of distinctive architectures with desirable physicochemical characteristics. Herein, we report a biochemistry-directed "bottom-up" approach to construct hollow porous microspheres of polyanion materials for sodium ion batteries. Two kinds of polyanions, i.e. Na3V2(PO4)3 and Na3.12Fe2.44(P2O7)2, are employed as cases in this study. The microalgae cell realizes the formation of a spherical "bottom" bio-precursor. Its tiny core is subjected to destruction and its tough shell tends to carbonize upon calcination, resulting in the hollow porous microspheres for the "top" product. The nanoscale crystals of the polyanion materials are tightly enwrapped by the highly-conductive framework in the hollow microsphere, resulting in the hierarchical nano-microstructure. The whole formation process is disclosed as a "bottom-up" mechanism. Moreover, the biochemistry-directed self-assembly process is confirmed to play a crucial role in the construction of the final architecture. Taking advantage of the well-defined hollow-microsphere architecture, the abundant interior voids and the highly-conductive framework, polyanion materials show favourable sodium-intercalation kinetics. Both materials are capable of high-rate long-term cycling. After five hundred cycles at 20 C and 10 C, Na3V2(PO4)3 and Na(3.12)Fe2.44(P2O7)2 retain 96.2% and 93.1% of the initial capacity, respectively. Therefore, the biochemistry-directed technique provides a low-cost, highly-efficient and widely applicable strategy to produce high-performance polyanion-based cathodes for sodium ion batteries.

In ultrasonic testing of coarse-grained materials, signal to noise ratio (SNR) of testing signals is reduced seriously for the structure noise, and echoes from defects are difficult to be identified. In order to improve the SNR and the reliability of ultrasonic testing of coarse-grained materials, empirical mode decomposition (EMD) is introduced to process the testing signal here. Signal envelope can be formed by using cubic spline interpolation, and nonlinear and non-stationary signal can be decomposed self-adaptive into the sum of several intrinsic mode functions (IMF) by using characteristic time scale of the signals, and then higher order and tendency of the original signals can be obtained. The denoising experiment with low SNR simulated signal are achieved according to the feature of EMD, and SNR is enhanced more by comparison with the wavelet analysis method. And testing signal collected from coarse-grained materials is used to finish denoising experiment, and it is shown from the experiment result that the EMD has better adaptive ability in decomposing noise-polluted signals and less empirical information is required in the denoising process. DOI: http://dx.doi.org/10.11591/telkomnika.v11i9.3286

Synthetic aperture focusing technique (SAFT) has a promising approach in ultrasonic nondestructive testing (NDT) methods and subsequently focuses on the data measured on an aperture to every point of the reconstructed imaging area through the superposition of the time records. To validate the potential of this method, an experimental system is established to perform cross-surface scan of the test specimen, and a SAFT processing program is used to give a 2-D display of the inner structure of the specimen based on the measured backscattered ultrasonic signals. Two different concrete specimens were cast with embedded objects. Design of the inspection pulse, for example, the pulse shape and central frequency is discussed. According to SAFT imaging algorithm, the images of these concrete structures are pictured. Compared to the original B-scan method, SAFT gives a better imaging quality.

Transfer character of ultrasonic transducer often influences on the test signal partly, and then test errors arise. To the problem, a compact method is proposed to calibrate the transfer character in this paper. The experiment data was obtained in water- immerging test of the transducers, and a discrete transfer function is established based on system identification algorithms and then used for transducer calibration. The method is validated effective by experiment. Not only can the characteristic of transducers be indicated, but also a referenced method is presented for calibrating the transfer character of LTI system.

In ultrasonic pulse-echo NDT of structures, the transducers usually operate in its harmonic frequencies in order to maximize the amplitude response. However, there exist some unwanted effects in such mode. For instance, the generated/detected signals will have long ringing, which means the time-domain resolution will be reduced. Presented here is a digital filtering method to compensate the unwanted frequency response characteristics of transducers. The first step is to establish a discrete transfer function model of transducer system based on time-domain system identification algorithms. Then the established model can be realized by a digital compensation filter to reduce the ringing effects of the measured signals. Experimental verification of the proposed method is carried out. After calibrating and modeling for transducers by water-immersion test, a compensation model is established and used to the thickness measurement of a concrete specimen. The compensation results show that the ring of transducer can be greatly reduced and the reflection from bottom of the specimen can be extracted from the original overlapped signals. To further validate the effect of the proposed method, its application in B-scan imaging of a concrete element with embedded anomaly is also given.

Concrete is one of the main construction materials in civil engineering. Among the existing Nondestructive Testing (NDT) methods, the imaging techniques that can give a graphic display of the inner structure of the concrete elements have received great attention. Because of several kinds of disturbing signals in the concrete structures imaging by low frequency ultrasound, low signal-noise ratio and poor resolution are engendered. Synthetic Aperture Focusing Technique (SAFT) is one of effect methods in the ultrasonic NDT area, and can focus effectively to reflected waves, and improve the reconstructed image’s resolution through rough B-scan method. For low-frequency excitation signal, however, wavepacket distortion is produced during the focusing process, which decreases test resolution. Therefore, Wavepacket Decomposition Technique (WDT), which can put the whole reflected wavepacket into focusing calculation, is introduced here to improve the reconstructed resolution. This technique solves the problem of wavepacket distortion, and better focusing effect and resolution are obtained. Furthermore, calculating velocity is increased because the points joined into SAFT calculation are cut down greatly. The presented technique has been verified by the simulation experiment. From the results, the method can improve more the ability of localizing object and give better imaging effect.