Doped elements in alloys significantly impact their performance. Conventional methods usually sputter the surface material of the sample, or their performance is limited to the surface of alloys ...owing to their poor penetration ability. The X-ray K-edge subtraction (KES) method exhibits great potential for the nondestructive in situ detection of element contents in alloys. However, the signal of doped elements usually deteriorates because of the strong absorption of the principal component and scattering of crystal grains. This in turn prevents the extensive application of X-ray KES imaging to alloys. In this study, methods were developed to calibrate the linearity between the grayscale of the KES image and element content. The methods were aimed at the sensitive analysis of elements in alloys. Furthermore, experiments with phantoms and alloys demonstrated that, after elaborate calibration, X-ray KES imaging is capable of nondestructive and sensitive analysis of doped elements in alloys.
BackgroundCustoms biosafety inspection is of great significance for maintaining ecological balance and protecting rare wild animals and plants.PurposeTo overcome the problem of poor contrast in ...traditional X-ray imaging systems for customs biosecurity inspections, an inspection instrument based on X-ray phase contrast imaging planned to be developed in this work.MethodsThe on-line phase contrast imaging method with high photon utilization efficiency was adopted in order to meet the requirements of high-efficiency data acquisition and fast imaging for the customs inspection. The protective shed shielding, security linkage and automatic sample stage were used in the instrument to ensure radiation safety in the inspection and the convenience of sample switching and adjustment. The methods of phase contrast micro-CT and three-dimensional micro-structure quantitative analysis were applied for biometrics recognition of specimens.ResultsA biometrics recognition instrument based on X-ray phase contrast imaging is dev
Abstract Previous studies have shown that the expression of miR-211 was downregulated in hepatocellular carcinoma (HCC). However, the molecular function and mechanism of miR-211 in HCC growth and ...invasion are largely unclear. We found that miR-211 is downregulated in HCC tissues and cell lines, respectively. Further results showed that low miR-211 associated with TNM stage, vein invasion status and poor prognosis. Ectopic expression of miR-211 effectively suppressed HCC cell proliferation, migration and invasion both in vitro and in vivo . We identified SPARC as a bona fide target of miR-211 and overexpression of miR-211 decreased the mRNA and protein expression of SPARC. Finally, we confirmed that the overexpression of SPARC in miR-211-expressing HCC cells can partially restore the inhibitory effect of miR-211. Taken together, our results demonstrated that loss of miR-211 expression and thus uncontrolled SPARC overexpression might drive progression of HCC, which may provide a novel therapeutic strategy for the treatment of HCC.
In this work, a rapid, environment friendly and sensitive method was established for the extraction and analysis of five organophosphorus pesticides (OPPs) (chlorpyrifos, chlorpyrifos-methyl, ...isocarbophos, malathion and phorate) in milk samples by means of gas chromatography-flame photometric detection. The pesticides were first extracted with acetonitrile from milk samples by using the modified “quick, easy, cheap, effective, rugged, and safe” (QuEChERS) method. No other clean-up was required after extraction. Then the above-mentioned acetonitrile extract was concentrated by using the dispersive liquid–liquid microextraction combined with solidification of floating organic droplets technique. Several factors that could influence the extraction efficiency, such as type of extraction solvent, disperser solvent, volume of extraction and disperser solvent, salt effect, sample pH, and extraction time, were investigated and optimized. As a result, 15 µL of 1-dodecanol were used as the extractant because of its lower toxicity, 300 µL methanol was chosen as dispersant and the extraction time was set to 1 min. Under the optimized conditions, good linearity was exhibited from 0.01 to 1.0 mg/L with the correlation coefficients higher than 0.9968. The limits of detection of the five OPPs were ranged in 0.1–0.3 μg/L, and the limits of quantification were at the range of 0.3–1.0 μg/L. Moreover, the recoveries of the target analytes from milk samples at spiking levels of 0.01, 0.05 and 0.1 mg/L were between 80.5 and 106.5% with the relative standard deviations varied from 3.6 to 6.3%. This method has been successfully applied to detect OPPs in real milk samples.
Power delivering with galvanic isolation is essential to guarantee system safety and reliability in harsh industry environments. However, efficiently transferring power of hundreds of mW across an ...isolation barrier is challenging for such size- and cost-constrained applications. Isolated capacitive power transfer using on-chip capacitors and an off-chip inductor is demonstrated in 1, but it only delivers 62mW power with less1 kV isolation voltage that is limited by the on-chip capacitors. To increase the output power and the isolation voltage, isolated DC-DC converters using silicon-based post-processed micro-transformers have been reported recently 2 -4. In 2, 6-\mu \mathrm{m}-thick plated Au are used for both the primary and the secondary coil windings to achieve quality factors of 6.8 at 200MHz, while the efficiency of the converter is lower than 34% with a maximum output power of 0.8W. A performance-enhanced micro-transformer using a magnetic core is proposed in 3 to achieve a peak efficiency of 52% and a maximum output power of 1.1W. However, the fabrication process of such a transformer is complex and the cost is high. In 4, the micro-transformer is formed by using ultra-thick metal windings, and high inductances with high quality factors are achieved to allow the converter to switch at 11MHz. However, the topology proposed produces large resonant currents that flow into the coils, degrading the efficiency to 34% with only 165mW output power. Moreover, the abovementioned isolated converters are assembled in a small-outline integrated-circuit (SOIC) 8-lead 2 or 28-lead 3 packages that measure 6mm \times 10 mm or 10mm \times 18 mm, respectively, resulting in a maximum power density of only 13.33mW/mm 2 .
Synchrotron-based X-ray micro-fluorescence (μ-SXRF) is a non-destructive analytical technique and has been widely used to detect and quantify the elemental composition of samples in their natural ...state. To determine the internal elemental distributions within samples, X-ray fluorescence microtomography has been developed based on the hard X-ray microprobe at beamline BL15U1 of the Shanghai Synchrotron Radiation Facility (SSRF) in Shanghai, China. This technique was applied to image the cross-sectional distributions of multiple elements within a single human hair, and its validity was evaluated by comparing the results with the elemental maps of a thin hair section obtained using the well-established μ-SXRF mapping method. Elemental images of S, Ca, Mn, Fe, Cu, and Zn within a virtual slice of the hair were reconstructed after the tomographic measurements. The tomographic images of heavy elements like Fe, Cu, and Zn were found to be in good agreement with the corresponding μ-SXRF maps. Light elements, such as S, however, represented different patterns due to non-negligible self-absorption in the sample, and sophisticated correction algorithms accounting for such effects are required for obtaining qualitatively and quantitatively more accurate images. Compared to μ-SXRF mapping, X-ray fluorescence microtomography reduces the sample preparation requirements and has been demonstrated in this work as being a more ideal and effective imaging modality to non-destructively mapping out the internal distribution of heavy elements within samples at the micrometer scale at the SSRF.
This article presents finite-time stabilization methods of switched linear systems with disturbances. After extending finite-time stabilization and finite-time boundedness definitions to switched ...linear systems, sufficient conditions guaranteeing system finite-time boundedness are proposed, by which the state feedback controller method is obtained. For a class of switched terminal guidance systems, the methods are illustrated by application to guidance design to solve the finite-time stabilization problem considering nonzero initial conditions and state constraints.
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