[en] In the context of computed tomography (CT), a key techniques is the image reconstruction from projection data. The filtered back projection (FBP) algorithm is commonly used in image reconstruction. Based on cause analysis of the artifacts, we propose a new image reconstruction algorithm combining the Wiener filter and FBP algorithm. The conventional FBP image reconstruction algorithm is improved by adopting Wiener filter: and artifacts in the reconstructed images are obviously reduced. Experimental results of typical flow regimes show that the improved algorithm can effectively improve the image quality. (authors)

[en] This paper studies the energy resolution and time resolution of scintillation detector produced by SEN-LE Company with appropriate measuring method. The detector is composed by LYSO crystal (model MicroFC-30035-SMT), and the coupling size of SiPM optical-electrical converter is 3 × 3 × 10 mm. The measuring result of the detector is: the energy of ²²Na radioactive source is 511 keV, the energy resolution (FWHM) of 511 keV photon is 16%, and the time resolution is 135 ps. (authors)

[en] Non-enzymatic hydrogen peroxide (H_2O_2) sensors were fabricated on the basis of glassy carbon (GC) electrode modified with palladium (Pd) core-platinum (Pt) nanodendrites (Pt-NDs) and poly (diallyldimethylammonium chloride) (PDDA)-coated reduced graphene oxide (rGO). A facile wet-chemical method was developed for preparing Pd core-Pt nanodendrites. In this approach, the growth of Pt NDs was directed by Pd nanocrystal which could be regarded as seed. The PDDA-coated rGO could form uniform film on the surface of GC electrode, which provided a support for Pd core- Pt NDs adsorption by self-assembly. The morphologies of the nanocomposites were characterized by transmission electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction (spectrum). Electrocatalytic ability of the nanocomposites was evaluated by cyclic voltammetry and chronoamperometric methods. The sensor fabricated by Pd core-Pt NDs/PDDA-rGO/GCE exhibited high sensitivity (672.753 μA mM"−"1 cm"−"2), low detection limit (0.027 μM), wider linear range (0.005–0.5 mM) and rapid response time (within 5 s). Besides, it also exhibited superior reproducibility, excellent anti-interference performance and long-term stability. The present work could afford a viable method and efficient platform for fabricating all kinds of amperometric sensors and biosensors. - Highlights: • A facial wet-chemical method was developed for preparing Pd core-Pt nanodendrites. • The morphologies of graphene and Pd core-Pt nanodendrites were characterized. • A novel H_2O_2 sensor was fabricated by nano-assembly. • The performance of H_2O_2 sensor was evaluated by cyclic voltammetry and chronoamperometric methods.

[en] Objective: To compare the image quality between volumetric high-resolution CT (VHRCT) and conventional high-resolution CT (CHRCT), and investigate the feasibility of VHRCT. Methods: Catphan 412 phantom was scanned with protocols of CHRCT and VHRCT on a set of GE Lightspeed VCT. The spatial-resolution (LP/cm), noise (standard deviation in an ROI) and radiation close (CTDI) were recorded for each CT scan. Difference of noise between CHRCT and VHRCT were evaluated by paired t test. In clinical study, 32 patients were scanned with VHRCT and CHRCT protocols. The image quality of CHRCT and VHRCT was rated and compared. The quality difference between CHRCT and VHRCT was assessed by Wilcoxon paired signed rank sum test. Results: In phantom study, the in-plane spatial-resolution of both VHRCT and CHRCT was 11 LP/cm for axial images and 12 LP/cm for coronal reformatted images. The noise of VHRCT and CHRCT was (69.18±2.77)HU and (54.62±2.12) HU respectively (t=-15.929, P<0.01) at the same dose level. The radiation dose of VHRCT was 19.09 mGy higher than CHRCT at the same noise level. In clinical study, the quality assessment scores of VHRCT axial images and CHRCT axial images were 3.22 and 3.24 respectively, with no significant difference(Z=-0.319, P>0.05). The quality assessment scores of VHRCT coronal reformatted images and CHRCT coronal reformatted images were 3.05 and 1.88 respectively with significant difference (Z= -5.088, P<0.01). Conclusion: The image quality of VHRCT cross-sectional image is similar to that of CHRCT. Multiplanar images with high resolution of VHRCT are recommended. The radiation dose of VHRCT remains to be optimized. (authors)

[en] Objective: To further improve the recognition to the imaging and histological findings and genetics characteristics of Fahr disease, and to analyze the pathogenesis of cystification. Methods: The epidemiological investigations were performed in 3 (2 females, 1 male) patients. Two patients were confirmed by surgicopathology combining with the clinical representation and laboratorial examination, 1 patient was diagnosed by the clinical and laboratorial examination. Combining with review of related literature, the histological features and pathogenesis of complications (including cystification and hemorrhage) and genetics characters were analysed. Results: The imaging examination demonstrated that Fahr disease mainly presented the symmetrical calcification in bilateral basal nuclei areas and subcortex in 3, furthermore, the bilateral calcification of dentatum in 1 and the unilateral in 1, the cystification in 2 (one in the right frontal lobe, the other in the left parietal lobe). The content of blood calcium and serum inorganic phosphorus was normal in the laboratorial examination. The pathological examinations revealed the siderocytes caused by chronic hemorrhage and some small vessels that most were hyalinosis and a few were fibrinoid necrosis, and that there were sand-like and irregular calcification inner or around vessel wall, thrombosis in vessel cavity and arteritis, and that hemosiderin aggregated in the cystic wall. Conclusion: Most of Fahr disease can be diagnosed according to the imaging features combining with laboratorial examination. The hemorrhage and cystification in the brain should be regarded as the complications of Fahr disease. CT has higher diagnostic value than X-ray plain film and MRI because of higher density resolution. (authors)

[en] The aim of this study was to investigate the effect of TiO₂ /N-succinyl-chitosan composite (TiO₂ / NSCS) photodynamic therapy (PDT), while considering the effects of various light sources on the activation of photosensitizer. The methyl thiazolyl tetrazolium assay was used to examine the cell survival rate of the cells. The results showed that glioma cell strain (U251) was the most sensitive cancer cell strain to TiO₂ /NSCS. When the concentration of TiO₂ /NSCS was between 0 and 800 μg·mL^-1, there was no obvious cytotoxicity to normal liver cells (HL-7702) and U251 cells. During the PDT process, the photokilling effect of TiO₂ /NSCS on U251 cells under ultraviolet-A (UVA) light irradiation was stronger than that of pure TiO₂, and its killing effects were positively correlated with concentration and irradiation time. In addition, both UVA and visible light could excite TiO₂ / NSCS, which had significant killing effect on U251 cells. The results of acridine orange/ethidium bromide fluorescent double staining and Annexin V/propidium iodide double staining indicated that TiO₂ /NSCS under UVA and visible light irradiation could kill U251 cells by inducing apoptosis, and the apoptosis rate of TiO₂ /NSCS treatment groups was higher than that of TiO₂ treatment groups. Therefore, TiO₂ /NSCS might be used as a potential photosensitizer in PDT. (author)

[en] Based on the theory of Compton scattering array detection, simulations using MCNP were performed for improving the efficiency and quality of Compton scattering detection. The results show a good scattering detection angle and an effective range. In addition, considering features of discriminate grade CdZnTe detector array, optimized collimator structure of the detection device was designed for detecting the multi-angle scattering information, and the detection efficiency was improved with reduced interference of other scatterings. (authors)

[en] Ni-Co-Al₂O₃-MoS₂ composite coatings were prepared on the surface of LY12 aluminum alloys by electrophoresis-electrodeposition with different MoS₂ concentrations. The microstructure, morphologies and composition of Ni-Co-Al₂ O₃-MoS₂ composites were characterized by X-ray diffractometer (XRD) and scanning electron microscopy (SEM) equipped with energy dispersive spectroscope (EDS). The micro-indentation hardness as well as friction and tribological properties of the coatings were tested by micro-hardness tester and friction and wear tester separately. Results revealed that the composite coating fabricated at 1.0 g⋅L^-1 MoS₂ achieved dense structure, and the average thickness of the coating was 39.820 μm. The micro-indentation hardness of the composite coating was decreased from 578 HV to 465 HV with the increase of MoS₂ concentration. Also, the composite coating synthesized at 1.0 g·L^-1 MoS₂ had the lowest friction coefficient and wear rate. (author)

[en] Highlights: • Cl₂ decreased algae fluorescence but cells size do not remarkably varied. • O₃ led to more cells with decreased size but less reduction in fluorescence. • Pre-chlorination increased DBP yields detected after coagulation-filtration. • Pre-ozonation decreased total DBP yields detected after coagulation-filtration. • Pre-oxidation affected HAA&chloral precursors more greatly than THM precursors. -- Abstract: Effect of pre-chlorination and pre-ozonation on Microcystis aeruginosa (MA) and Coccomyxa subellipsoidea (CS) as disinfection by-products (DBPs) precursors was investigated after coagulation-filtration. Pre-chlorination considerably decreased the autofluorescence of algae cells but barely influenced cell granularity. In comparison, after pre-ozonation more algae cells were associated with decreased cell size; yet less reduction in the autofluorescence was observed. In MA case, pre-chlorination increased the residual algae density after coagulation-filtration by 132%–146% while pre-ozonation enhanced the algae removal by 26%–28%. In CS case, algae removal was improved by pre-chlorination (32%–45%) and pre-ozonation (7%–45%). Pre-chlorination enhanced the removal of algogenic organic matters (AOM) by coagulation-filtration, especially for tryptophan-like and soluble microbial products. Effect of pre-ozonation on the fluorescence intensity of AOM after coauglation-filtration depended on AOM species and the ratio of [ozone dose]:[algae density]. In both MA and CS cases, chlorine increased the yields of trihalomethane (THM, 25%–78% and 51%–103%), haloacetic acid (HAA, 140%–360% and 167%–233%) and chloral (50%–161% and 68%–108%), respectively. Pre-ozonation decreased the total DBPs yields. For MA-added suspensions, ozone decreased the production of THM, HAA and chloral by 15%–37%, 28%–39% and 60%, respectively. In CS case, chloral yield was decreased by 12%–31% while THM formation was largely unchanged. HAA production varied by ± 1.5 μg/L.

[en] A novel Co–WC composite coating was fabricated on the surface of high-speed steel (HSS) substrate by direct current (DC) electrodeposition. The co-electrodeposition mechanism of Co–WC composite coating was explored. Furthermore, the effects of process parameters on the microstructure and micro-hardness of the coating were studied. The microstructure and composition of Co–WC composite coating were investigated by scanning electron microscopy equipped with an energy dispersive x-ray spectroscope. The adhesion strength of Co–WC composite coating was evaluated by WS-2005 automatic scratch tester. Results revealed that WC particles were homogeneously embedded in the Co matrix with few defects, and the Co–WC composite coating was firmly bonded to the HSS substrate. The optimized parameters are as follows: WC concentration of 35 g l⁻¹, current density of 6.5 Adm⁻², stirring rate of 300 rpm, and pH of 7.5 and temperature of 50 °C. X-ray diffraction analysis indicated that the Co matrix combined physically with the WC particles. Also, the microindentation hardness of Co–WC composite coating was tested by micro-hardness tester. It was found that the microindentation hardness of Co–WC composite coating reached the maximum value of 542 HV under the optimal process conditions. (paper)