Secondary Interface Echoes Suppression for Immersion Ultrasonic Imaging Based on Phase Circular Statistics Vector.

Immersion ultrasonic phased array imaging technology offers great advantages, particularly in coupling and automatic detection of industrial non-destructive testing (NDT). To suppress the influence of secondary interface echoes in the immersion ultrasonic phased array imaging, a novel phase circular statistics vector (PCSV) weighting method is proposed in this paper. Firstly, the PCSV factor matrix is established according to the phase consistency of the echo signals. Secondly, due to the higher phase coherence of the defect echo, the PCSV factor matrix is used to weight the TFM image to suppress the secondary interface echo. The result shows the secondary interface echoes are effectively suppressed in the total focusing method (TFM) image on a 0~40 dB scale. It is also shown that PCSV weighting could not only suppress the secondary interface echoes but also improved the image quality in terms of SNR and lateral resolution by comparing with traditional TFM.

Bacteria-engineered porous sponge for hemostasis and vascularization.

BACKGROUND: Hemostasis and repair are two essential processes in wound healing, yet early hemostasis and following vascularization are challenging to address in an integrated manner. RESULTS: In this study, we constructed a hemostatic sponge OBNC-DFO by fermentation of Komagataeibacter xylinus combined with TEMPO oxidation to obtain oxidized bacterial nanocellulose (OBNC). Then angiogenetic drug desferrioxamine (DFO) was grafted through an amide bond, and it promoted clot formation and activated coagulation reaction by rapid blood absorption due to the high total pore area (approximately 42.429 m2/g measured by BET). The further release of DFO stimulated the secretion of HIF-1α and the reconstruction of blood flow, thus achieving rapid hemostasis and vascularization in damaged tissue. This new hemostatic sponge can absorb water at a rate of approximate 1.70 g/s, rapidly enhancing clot formation in the early stage of hemostasis. In vitro and in vivo coagulation experiments (in rat tail amputation model and liver trauma model) demonstrated superior pro-coagulation effects of OBNC and OBNC-DFO to clinically used collagen hemostatic sponges (COL). They promoted aggregation and activation of red blood cells and platelets with shorter whole blood clotting time, more robust activation of endogenous coagulation pathways and less blood loss. In vitro cellular assays showed that OBNC-DFO prevailed over OBNC by promoting the proliferation of human umbilical vein endothelial cells (HUVECs). In addition, the release of DFO enhanced the secretion of HIF-1α, further strengthening vascularization in damaged skin. In the rat skin injury model, 28 days after being treated with OBNC-DFO, skin appendages (e.g., hair follicles) became more intact, indicating the achievement of structural and functional regeneration of the skin. CONCLUSION: This hemostatic and vascularization-promoting oxidized bacterial nanocellulose hemostatic sponge, which rapidly activates coagulation pathways and enables skin regeneration, is a highly promising hemostatic and pro-regenerative repair biomaterial.

Analysis of molecular variation of porcine reproductive and respiratory syndrome virus in Central China from 2006 to 2012.

To analyze the epidemiology of PRRSV in Hubei Province of China, 668 serum samples collected from 14 pig-breeding farms were tested. We found that the PRRSV-positive rate was 5.24 % and that HP-PRRSV had become the dominant strain. To further investigate the genetic variation of PRRSV strains in this region, the complete gene sequences of nsp2, orf5, and orf7 from nine PRRSV strains collected during 2011-2012 were determined and compared with 33 known sequences. The results revealed that diverse HP-PRRSV strains are present in this region. An analysis of orf5 gene sequences showed that the strains collected during 2009-2010 formed a tightly clustered branch. When compared with the JXA1 strain, they had one mutation (V29 → A29) in a decoy epitope. Furthermore, we found that the number of potential N-glycosylation sites had apparently increased since 2006. These findings increase our knowledge of PRRSV epidemiology in Central China.

Improved Coherent Plane-Wave Compounding Using Sign Coherence Factor Weighting for Frequency-Domain Beamforming.

This study proposes a novel modified sign coherence factor (SCF) weighting adapted to the frequency-domain (FD) beamforming for ultrasound plane-wave imaging to achieve a high frame rate and better image quality. First, before beamforming, the sign components were extracted from the radiofrequency signals of aperture data. Second, the modified SCF was established using the FD beamformed sign components. Finally, the FD beamformed image was weighted by the modified SCF. To assess the performance of the proposed modified SCF for FD beamforming, the resolution, contrast, computation complexity and execution time of the generated images were evaluated. The results revealed that the FD-SCF could significantly improve the computational load compared with the classic delay-and-sum SCF on the premise of equal image quality improvement. Therefore, high image quality and low computational load have been successfully combined under the proposed weighting method.

Circular statistics vector for improving coherent plane wave compounding image in Fourier domain.

In this work, a circular statistics vector (CSV) weighting Fourier domain (FD) beamforming for ultrasound plane-wave images was proposed to achieve better image quality with a high frame rate. Firstly, the cosine and sine components of the instantaneous phase are extracted from undelayed RF signals. Secondly, the FD beamformed cosine and sine components are used to establish the CSV. Finally, the FD beamformed amplitude image is weighted by the CSV. The resolution, contrast, and computation complexity were used to assess the performance of the proposed method. The results revealed that FD_CSV could significantly reduce the computational load compared to the conventional DAS_CSV on the equal improvement of image quality. Besides, compared to coherence factor (CF), phase coherence factor (PCF), etc., based on variance calculation, the CSV based on mean resultant vector calculation can effectively preserve the speckle due to the more tolerant to phase errors. The proposed FD_CSV weighting method has successfully conducted high image quality and low computational load.

Genetic and Molecular Characterization of H9N2 Avian Influenza Viruses Isolated from Live Poultry Markets in Hubei Province, Central China, 2013-2017.

H9N2 subtype avian influenza virus (AIV) is an influenza A virus that is widely spread throughout Asia, where it jeopardizes the poultry industry and provides genetic material for emerging human pathogens. To better understand the epidemicity and genetics of H9 subtype AIVs, we conducted active surveillance in live poultry markets (LPMs) in Hubei Province from 2013 to 2017. A total of 4798 samples were collected from apparent healthy poultry and environment. Real-time RT-PCR revealed that the positivity rate of influenza A was 26.6% (1275/4798), of which the H9 subtype accounted for 50.3% (641/1275) of the positive samples. Of the 132 H9N2 viral strains isolated, 48 representative strains were subjected to evolutionary analysis and genotyping. Phylogenetic analysis revealed that all H9N2 viral genes had 91.1%-100% nucleotide homology, clustered with genotype 57, and had high homology with human H9N2 viruses isolated from 2013 to 2017 in China. Using a nucleotide divergence cutoff of 95%, we identified ten distinct H9N2 genotypes that continued to change over time. Molecular analysis demonstrated that six H9N2 isolates had additional potential glycosylation sites at position 218 in the hemagglutinin protein, and all isolates had I155T and Q226L mutations. Moreover, 44 strains had A558V mutations in the PB2 protein and four had E627V mutations, along with H9N2 human infection strains A/Beijing/1/2016 and A/Beijing/1/2017. These results emphasize that the H9N2 influenza virus in Hubei continues to mutate and undergo mammalian adaptation changes, indicating the necessity of strengthening the surveillance of the AIV H9N2 subtype in LPMs.

MicroRNA-29a upregulates MMP2 in oral squamous cell carcinoma to promote cancer invasion and anti-apoptosis.

Abnormal microRNA expression is a common and important feature of human malignancies. Matrix metalloproteinase 2 (MMP2), which has been reported in several cancers, plays important roles in cancer progression. However, the microRNA regulatory mechanism on MMP2 expression remains unclear. In this study, we first detected MMP2 and microRNA-29a (miR-29a) expression in oral squamous carcinoma (OSCC) specimens, which showed that MMP2 was higher in OSCC cancer tissues than adjacent tissues but that miR-29a was lower in OSCC cancer tissues than adjacent tissues. Then, we confirmed that miR-29a, which directly targeted 3'-UTR of MMP2 gene, negatively regulated MMP2 expression by miR-29a transfection and luciferase reporter assay. Exogenous overexpression of miR-29a inhibited OSCC cell invasion and anti-apoptosis significantly in vitro. Whereas, knockdown of miR-29a promoted OSCC cell invasion and induced drug-resistance in vitro. This study suggests that miR-29a plays an inhibiting role in the progression of OSCC, which may be a potentially therapeutic approach in the future.

[Effects of two endodontic sealers on the bond strength of two fiber posts].

OBJECTIVE: To study the effects of two different endodontic sealers on the bond strength of two fiber posts cemented with adhesive resin cement. METHODS: Twenty-eight crownless human maxillary central incisors were prepared with the step-back technique and randomly divided into four groups according endodontic sealer and fiber: Group A, Cortisomol sealer+Matchpost fiber post; Group B, Cortisomol sealer+Macrolock fiber post; Group C, Guttaflow sealer+Matchpost fiber post; Group D, Guttaflow sealer+Macrolock fiber post. One week after fiber posts were bonded, a thin-slice push-out test was performed in a universal machine. Morphologic structure of the root canal dentin surfaces etched and the adhesive interfaces were examined by scanning electron microscopy (SEM). RESULTS: The bond strengths of 4 groups were (7.06 +/- 3.22), (9.31 +/- 3.61), (6.90 +/- 3.13), (9.71 +/- 3.42) MPa. The bond strengths of group B and D were significantly higher than that of group A and C (P < 0.05). There was no significant difference between group A and C, group B and D (P > 0.05). The cervical third had the highest mean push-out bond strength, next to middle third and apical third (P < 0.01). SEM showed that larger numbers of the dentin tubules were open after the root canals were etched and penetration of resin tags into the dentinal tubules increased in the coronal root region when compared with the apical root region. CONCLUSION: The shear bond strength doesn't have relationship with endodontic sealers. The serration significantly increases the retention of fiber post. The bond strengths are different at the three root segment sites.

[Occluding effects of three new calcium desensitizers on dentinal tubules in vitro].

OBJECTIVE: To evaluate the occluding effects of three new calcium desensitizers on dentinal tubules in vitro. METHODS: Twenty-five dentin specimens of 1.00 mm thick from freshly extracted third molars were divided into five groups randomly. After treatment with 6% citric acid, group A was treated with distilled water, and group B-E were treated with NovaMin, Pro-Argin, casein phosphopeptide-amorphous calcium phosphate (CPP-ACP), and 75% NaF glycerin for 2 min respectively. Then the teeth were vertically cleaved into two sections. The surfaces and cross sections were observed by the scanning electron microscope (SEM) and energy dispersive X-ray (EDX), which were analyzed by the Image-Pro Plus software. RESULTS: The percentage of dentin tubules sealed were (81.6 ± 6.1)%, (71.5 ± 6.3)%, (43.2 ± 2.6)%, (39.9 ± 4.1)% for groups B, C, D and E respectively, and the occluding depth were (30.33 ± 2.26), (24.55 ± 2.58), (16.10 ± 4.65) and (8.90 ± 1.51) µm respectively. The differences between these groups were statistically significant (P < 0.01) except for group B and C (P > 0.05). However, there was no significant difference between all the groups for the Ca/P ratios (P = 0.342). CONCLUSIONS: NovaMin may have better immediate occluding effects than other desensitizers and could deposit a dentin-like mineral.