Lightweight magnesium alloys are attractive as structural materials for improving energy efficiency in applications such as weight reduction of transportation vehicles. One major obstacle for ...widespread applications is the limited ductility of magnesium, which has been attributed to Formula: see text dislocations failing to accommodate plastic strain. We demonstrate, using in situ transmission electron microscope mechanical testing, that Formula: see text dislocations of various characters can accommodate considerable plasticity through gliding on pyramidal planes. We found that submicrometer-size magnesium samples exhibit high plasticity that is far greater than for their bulk counterparts. Small crystal size usually brings high stress, which in turn activates more Formula: see text dislocations in magnesium to accommodate plasticity, leading to both high strength and good plasticity.
Mass transport driven by temperature gradient is commonly seen in fluids. However, here we demonstrate that when drawing a cold nano-tip off a hot solid substrate, thermomigration can be so rampant ...that it can be exploited for producing single-crystalline aluminum, copper, silver and tin nanowires. This demonstrates that in nanoscale objects, solids can mimic liquids in rapid morphological changes, by virtue of fast surface diffusion across short distances. During uniform growth, a thin neck-shaped ligament containing a grain boundary (GB) usually forms between the hot and the cold ends, sustaining an extremely high temperature gradient that should have driven even larger mass flux, if not counteracted by the relative sluggishness of plating into the GB and the resulting back stress. This GB-containing ligament is quite robust and can adapt to varying drawing directions and velocities, imparting good controllability to the nanowire growth in a manner akin to Czochralski crystal growth.
Environmentally friendly BiFeO3 capacitors have great potential for applications in pulsed-discharge and power conditioning electronic systems because of their excellent intensity of spontaneous ...polarization (Ps). Herein, (0.7−x)BiFeO3-0.3BaTiO3-xNaTaO3 + 0.3 wt% MnO2 (abbreviated as BF-BT-xNT) multilayer ceramic capacitors (MLCCs) were designed and prepared to improve the energy storage performance via enhancing ion bonding and dielectric relaxation. The BDS of BF-BT-xNT MLCCs from 500 kV cm−1 at x = 0.05 increases greatly to 800 kV cm−1 at x = 0.15 due to the increase of the band gap and resistance, and the decrease of dielectric permittivity. An excellent energy storage density Urec = 9.1 J cm−3 and efficiency η > 80% were obtained since ultrahigh BDS (780 kV cm−1) and low Pr value (2.1 μC cm−2 at measured electric field 780 kV cm−1) were achieved simultaneously in BF-BT-xNT multilayer capacitors at x = 0.12. This work provides a strategy for improving energy storage properties of BiFeO3, which is via enhancing ionic bonding and relaxor behavior to achieve high BDS, low Pr and large Pmax, simultaneously.
The study explored the preservation effect of Portulaca oleracea L. extract (POE) on pork meat under refrigerated conditions for 9 days. POE was tested for antioxidant activity and antibacterial ...activity in vitro and the results showed that POE has strong antioxidant activity and has antibacterial activity against Pseudomonas aeruginosa, Bacillus subtilis and Bacillus cereus to some extent. Effect of POE in different levels (0.25%, 0.50% and 1.0%) on quality and shelflife of pork meat storage were evaluated. Results showed that the treatments of POE significantly inhibited microbial growth,delayed lipids oxidation, reduced values of thiobarbituric acid reactive substances (TBARS) and total volatile base‑nitrogen (TVB-N), increased superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities and in a dose-dependent manner (P < .05). Concomitantly, 1.0%POE and 0.50%POE treatments had better appearance compared with control after 9 days storage. All results confirmed that POE could effectively maintain the quality of chilled pork compared to control.
•Portulaca oleracea L. extract was added to chilled pork meat in comparison to BHA and TP (tea polyphenol).•Shelflife of chilled pork treated with Purslane extract increased 2 days.•Chilled meat with Purslane extract presented better oxidative stability and sensory index.•As a potherb, Purslane processes high antioxidant activity and notable preservation effect.•Portulaca oleracea L. as natural food antioxidant has broad application and development value prospects.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
ABSTRACT
Objective
This study aimed to establish a highly sensitive and rapid single‐tube, two‐stage, multiplex recombinase‐aided qPCR (mRAP) assay to specifically detect the khe, blaKPC‐2, and ...blaNDM‐1 genes in Klebsiella pneumoniae.
Methods
mRAP was carried out in a qPCR instrument within 1 h. The analytical sensitivities of mRAP for khe, blaKPC‐2, and blaNDM‐1 genes were tested using recombinant plasmids and dilutions of reference strains. A total of 137 clinical isolates and 86 sputum samples were used to validate the clinical performance of mRAP.
Results
mRAP achieved the sensitivities of 10, 8, and 14 copies/reaction for khe, blaKPC‐2, and blaNDM‐1 genes, respectively, superior to qPCR. The Kappa value of qPCR and mRAP for detecting khe, blaKPC‐2, and blaNDM‐1 genes was 1, 0.855, and 1, respectively (p < 0.05).
Conclusion
mRAP is a rapid and highly sensitive assay for potential clinical identification of khe, blaKPC‐2, and blaNDM‐1 genes in K. pneumoniae.
We establish a highly sensitive and rapid single‐tube, two‐stage, multiplex recombinase‐aided qPCR (mRAP) assay to specifically detect the khe, blaKPC‐2, and blaNDM‐1 genes in Klebsiella pneumoniae (KP). mRAP was carried out in a qPCR instrument within 1 h. mRAP achieved the sensitivities of 10, 8, and 14 copies/reaction for khe, blaKPC‐2, and blaNDM‐1 genes, respectively, superior to qPCR.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Hepatitis B virus (HBV) infection is the major public health problem worldwide. In clinical practice, serological and molecular assays are the most commonly used diagnostic methods to detect HBV ...infection in clinical practices.
Here we present a rapid and sensitive recombinase aided amplification assay (RAA) to detect HBV at 39.0 °C for 30 min without DNA extraction from serum samples. The analytical sensitivity of RAA assay was 100 copies per reaction and showed no cross reaction with human immunodeficiency virus (HIV) and hepatitis C virus (HCV). The universality of RAA assay was validated by testing of 41 archived serum samples with predefined HBV genotypes (B, C and D).
A total of 130 archived suspected HBV infected serum samples were detected by commercial qPCR with DNA extraction and RAA assay without DNA extraction (heat-treatment). Compared with qPCR assay as a reference, the RAA assay obtained 95.7% sensitivity and 100% specificity and a kappa value of 0.818.
We developed a rapid, convenient, highly sensitive and specific method to detect HBV without DNA extraction in clinical samples. This RAA method of HBV detection is very suitable for clinical testing.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The most prevalent viruses currently causing diarrhea are norovirus and rotavirus, and rapid and sensitive detection methods are essential for the early diagnosis of disease. The purpose of this ...study was to establish a sensitive single‐tube two‐stage nucleic acid amplification method—reverse transcription recombinase‐assisted PCR (RT‐RAP)—for simultaneous detection of norovirus GII and group A Rotavirus, with the first stage consisting of isothermal reverse transcription recombinase‐aided amplification (RT‐RAA) and the second stage consisting of qPCR (quantitative PCR). RT‐RAP is more sensitive than either RT‐RAA or qRT‐PCR (quantitative RT‐PCR) alone. And the addition of a barrier that can be disassembled after heating enabled the detection of samples within 1 h in a single closed tube. Sensitivity was 10 copies/reaction of norovirus (Novs) GII and group A rotavirus (RVA). In parallel, two hundred fecal specimens were used to evaluate the method and compare it with a commercial fluorescent quantitative RT‐PCR. The data showed kappa values of 0.957 and 0.98 (p < 0.05) for detecting Novs GII and RVA by the two methods, indicating the potential of the newly established assay to be applied to clinical and laboratory testing.
A sensitive single‐tube two‐stage nucleic acid amplification method—reverse transcription recombinase‐assisted PCR (RT‐RAP)—for simultaneous detection of norovirus GII and group A Rotavirus with the first stage consisting of isothermal reverse transcription recombinase‐aided amplification (RT‐RAA) and the second stage consisting of qPCR (quantitative PCR).
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Multiplex real‐time quantitative polymerase chain reaction (mRT‐qPCR) assay is commonly used to detect respiratory viruses, however, the sensitivity is limited for most reports. A panel of locked ...nucleic acid based multiplex closed one‐tube nested real‐time PCR (mOTNRT‐PCR) assay consisting of five separate internally controlled RT‐qPCR assays was developed for detection of 14 respiratory viruses. The sensitivity and reproducibility of mOTNRT‐PCR panel were evaluated using plasmid standards and the specificity was evaluated using clinical samples. The clinical performance of mOTNRT‐PCR panel was further evaluated with 468 samples collected from patients with an acute respiratory infection and compared with individual real‐time PCR (RT‐qPCR) assay. The analytical sensitivities of mOTNRT‐PCR panel ranged from 2 to 20 copies/reaction, and no cross‐reaction with common respiratory viruses was observed. The coefficients of variation of intra‐assay and inter‐assay were between 0.35% and 8.29%. Totally 35 clinical samples detected by mOTNRT‐PCR assay panel were missed by RT‐qPCR and confirmed true positive by sequencing of nested PCR products. The mOTNRT‐PCR assay panel provides a more sensitive and high‐throughput method for the detection of 14 respiratory viruses.
Research Highlights
A panel of mOTNRT‐PCR consisted of five separate internally controlled RT‐qPCR assay.
Locked nucleic acid was used to develop the mOTNRT‐PCR assay panel.
The sensitivity of mOTNRT‐PCR panel ranged from 2‐20copies/reaction using plasmid.
mOTNRT‐PCR was more sensitive than reported individual RT‐qPCR assay.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Children with Down's syndrome (DS) might exhibit disrupted brain functional connectivity in the motor and prefrontal cortex. To inspect the alterations in brain activation and functional connectivity ...for children with DS, the functional near-infrared spectroscopy (fNIRS) method was applied to examine the brain activation difference in the motor and prefrontal cortex between the DS and typically developing (TD) groups during a fine motor task. In addition, small-world analysis based on graph theory was also carried out to characterize the topological organization of functional brain networks. Interestingly, behavior data demonstrated that the DS group showed significantly long reaction time and low accuracy as compared to the TD group (
<
). More importantly, significantly reduced brain activations in the frontopolar area, the pre-motor, and the supplementary motor cortex (
<
) were identified in the DS group compared with the TD group. Meanwhile, significantly high global efficiency (
) and short average path length (
) were also detected for the DS group. This pilot study illustrated that the disrupted connectivity of frontopolar area, pre-motor, and supplementary motor cortex might be one of the core mechanisms associated with motor and cognitive impairments for children with DS. Therefore, the combination of the fNIRS technique with functional network analysis may pave a new avenue for improving our understanding of the neural mechanisms of DS.
•Propose an arbitrary polygon-based CSFEM-PFCZM to investigate quasi-brittle fracture of concrete-like materials.•Successfully simulate macroscale and mesoscale heterogeneous problems.•Show evident ...flexibility and efficiency over traditional FEM-PFCZM.•Hold promise to increase the acceptance and momentum of both the CSFEM and PFCZM in the research communities.
In recent years, engineering and research communities have shown a growing interest in polygon elements due to their adaptability to complex geometries. However, their applicability for investigating the quasi-brittle damage and fracture of concrete structures is still an open question. This work thus develops a numerical framework to integrate the phase-field regularized cohesive zone model (PFCZM) with the cell-based smoothed finite element method (CSFEM) using arbitrary polygon elements. The techniques of centroidal Voronoi tessellation and polytree decomposition are adopted to discretize the computational domains and efficiently refine the potential cracking areas in a multi-level manner. This allows fast transition of the mesh density and direct elimination of the hanging-node issue using the CSFEM. To calculate the displacements and the damage variables, only Wachspress shape functions and boundary geometries are needed, eliminating the need for coordinate mapping and Jacobian inversion. For each CSFEM subcell, crack-driving forces are determined at the integration point and stored as history variables. Typical concrete structures under different loading conditions are validated with respect to the crack path and load-carrying capacity, exhibiting good coarse-mesh accuracy. A mesoscale test-piece under uniaxial tension is also modelled using the developed framework, showing significant computational efficiency when compared to the conventional FEM.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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