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Detection of gallbladder stones by dual-energy spectral computed tomography imaging
摘要： AIM: To evaluate the detectability of gallbladder stones by dual-energy spectral computed tomography (CT) imaging. METHODS: Totally 217 patients with surgically confirmed gallbladder stones were retrospectively analyzed who underwent single-source dual-energy CT scanning from August 2011 to December 2013. Polychromatic images were acquired. And post-processing software was used to reconstruct monochromatic (40 keV and 140 keV) images, and calcium-lipid pair-wise base substance was selected to acquire calcium base images and lipid base images. The above 5 groups of images were evaluated by two radiologists separately with 10-year experience in CT image reading. In the 5 groups of images, the cases in the positive group and negative group were counted and then the detection rate was calculated. The inter-observer agreement on the scoring results was analyzed by Kappa test, and the scoring results were analyzed by Wilcoxon test, with P < 0.05 indicating that the difference was statistically significant. The stone detection results of the 5 groups of images were analyzed by χ2 test. RESULTS: There was good inter-observer agreement (k = 0.772). In 217 patients with gallbladder stones, there was a statistically significant difference in stone visualization between spectral images (40 keV, 140 keV, calcium base and lipid base images) and polychromatic images (P < 0.05). 40 keV monochromatic images were better than 140 keV monochromatic images (4.90 ± 0.35 vs 4.53 ± 1.15, P < 0.05), and calcium base images were superior to lipid base images (4.91 ± 0.43 vs 4.77 ± 0.63, P < 0.05), but there was no statistically significant difference between 40 keV monochromatic images and calcium base images (4.90 ± 0.35 vs 4.91 ± 0.43, P > 0.05). In 217 gallbladder stone patients, there were 21, 3, 28, 5 and 12 negative stone cases in polychromatic images, 40 keV images, 140 keV images, calcium base images and lipid base images, respectively, and the differences among the five groups were statistically significant (P < 0.05). CONCLUSION: Monochromatic images and base substance images have a good clinical prospect in the iso-density stone detection.
关键词： Gallbladder stone,Spectral imaging,Computed tomography
更新于2025-09-04 15:30:14
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Effect of the stellar absorption line centre-to-limb variation on exoplanet transmission spectrum observations
摘要： Transit spectroscopy is one of the most commonly used techniques for exoplanet atmosphere characterisation. This technique has been used to detect ionised and neutral species in exoplanet atmospheres by comparing the observed stellar lines in and out of transit. The centre-to-limb variation (CLV) of the stellar lines across the stellar disk is an important effect for transmission spectroscopy, since it results in a change of stellar line depth when the planet transits different parts of the stellar disk. We reanalysed the transit data of HD 189733b taken with the HARPS spectrograph to study the CLV effect during transit. The transmission light curve of the Na i D line so obtained shows a clear imprint of the CLV effect. We used a one-dimensional non-LTE stellar spectral model to simulate the CLV effect. After applying the correction, the measurement of the Na i absorption in the atmosphere of HD 189733b becomes better determined. We compared the CLV effect of HD 189733b to that of HD 209458b. The CLV effects are different for these two benchmark planetary systems and this is attributed to their different stellar effective temperatures and transit impact parameters. We then explored the general CLV effect that occurs during exoplanet transits. Normally, a star with a lower effective temperature exhibits a stronger CLV effect and its CLV feature extends over a relatively broad wavelength range. The transit impact parameter (b) describes the transit trajectory on the stellar disk and thus determines the actual manifestation of the CLV effect. We introduced a b-diagram which describes the behaviour of the CLV effect as the function of different impact parameters. With improving observational precision, a careful modelling and correction of the CLV effect is necessary for exoplanet atmosphere characterisation using transit spectroscopy.
关键词： techniques: spectroscopic,stars: atmospheres,planets and satellites: atmospheres
更新于2025-09-04 15:30:14
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Entrainment Heat Flux Computed with Lidar and Wavelet Technique in Buenos Aires During Last Chaitén Volcano Eruption
摘要： At Lidar Division of CEILAP (CITEDEF-CONICET) a multiwavelength Raman-Rayleigh lidar optimized to measure the atmospheric boundary layer is being operated. This instrument is used for monitoring important aerosol intrusion events in Buenos Aires, such as the arrival of volcanic ashes from the Chaitén volcano eruption on May 2008. That was the first monitoring of volcanic ash with lidar in Argentina. In this event several volcanic ash plumes with high aerosol optical thickness were detected in the free atmosphere, affecting the visibility, surface radiation and therefore, the ABL evolution. In this work, the impact of ashes in entrainment flux ratio is studied. This parameter is obtained from the atmospheric boundary layer height and entrainment zone thickness using algorithms based on covariance wavelet transform.
更新于2025-09-04 15:30:14
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Graphene Synthesis by Plasma-Enhanced CVD Growth with Ethanol
摘要： A modified route to synthesize graphene flakes is proposed using the Chemical Vapor Deposition (CVD) technique, by using copper substrates as supports. The carbon source used was ethanol, the synthesis temperature was 950°C and the pressure was controlled along the whole process. In this CVD synthesis process the incorporation of the carbon source was produced at low pressure and 950°C inducing the appearance of a plasma blue flash inside the quartz tube. Apparently, the presence of this plasma blue flash is required for obtaining graphene flakes. The synthesized graphene was characterized by different techniques, showing the presence of non-oxidized graphene with high purity.
关键词： Chemical Vapor Deposition,Raman Spectroscopy,AFM,Plasma-Enhanced,Graphene Flakes
更新于2025-09-04 15:30:14
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Empirical estimation of astrophysical photodisintegration rates of <sup>106</sup> Cd
摘要： It has been noted in previous experiments that the ratio between the photoneutron and photoproton disintegration channels of 106Cd might be considerably different from predictions of statistical models. The thresholds of these reactions differ by several MeV and the total astrophysical rate of photodisintegration of 106Cd, which is mostly produced in photonuclear reactions during the p-process nucleosynthesis, might be noticeably different from the calculated value. In this work the bremsstrahlung beam of a 55.6 MeV microtron and the photon activation technique is used to measure yields of photonuclear reaction products on isotopically-enriched cadmium targets. The obtained results are compared with predictions of statistical models. The experimental yields are used to estimate photodisintegration reaction rates on 106Cd, which are then used in nuclear network calculations to examine the effects of uncertainties on the produced abundences of p-nuclei.
更新于2025-09-04 15:30:14
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Comparison with simulations to experimental data for photo-neutron reactions using SPring-8 Injector
摘要： Simulations of photo-nuclear reactions by using Monte Carlo codes PHITS and FLUKA have been performed to compare to the measured data at the SPring-8 injector with 250MeV and 961MeV electrons. Measurement data of Bismuth-206 productions due to photo-nuclear reactions of 209Bi((cid:538),3n)206Bi and high energy neutron reactions of 209Bi(n,4n)206Bi at the beam dumps have been compared with the simulations. Neutron leakage spectra outside the shield wall are also compared between experiments and simulations.
更新于2025-09-04 15:30:14
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An Imaging Algorithm for a Lunar Orbit Interferometer Array
摘要： Radio astronomical observations below 30 MHz are hampered by the refraction and absorption of the ionosphere as well as the radio frequency interference (RFI), and thus, high angular resolution sky intensity map is not yet available. An interferometer array on lunar orbit provides a perfect observatory in this frequency band: it is out of the ionosphere, and the Moon helps to block the RFIs from the Earth. The satellites can make observations on the far side of the Moon and then send back the data on the near-side part of the orbit. However, for such arrays, the traditional imaging algorithm is not applicable: the ?eld of view is very wide (almost whole-sky), and for baselines distributed on a plane, there is a mirror symmetry between the two sides of the plane. A further complication is that for each baseline, the Moon blocks part of the sky, but as the satellites orbit the Moon, both the direction of the baseline and the blocked sky change, so even imaging algorithms that can deal with a noncoplanar baseline may not work in this case. Here, we present an imaging algorithm based on solving the linear mapping equations relating the sky intensity to the visibilities. We show that the mirror symmetry can be broken by the three-dimensional baseline distribution generated naturally by the precession of the orbital plane of the satellites. The algorithm is applicable and good maps can be reconstructed, even though the sky blocking by the Moon is different for each baseline. We also investigate how the map-making is affected by inhomogeneous baseline distributions.
关键词： space vehicles: instruments,?rst stars,radio continuum: general,dark ages,reionization,techniques: interferometric,instrumentation: interferometers,methods: data analysis
更新于2025-09-04 15:30:14
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THE BOSS EMISSION-LINE LENS SURVEY. IV. SMOOTH LENS MODELS FOR THE BELLS GALLERY SAMPLE
摘要： We present Hubble Space Telescope F606W-band imaging observations of 21 galaxy-Lyα emitter lens candidates in the Baryon Oscillation Spectroscopic Survey Emission-Line Lens Survey (BELLS) for the GALaxy-Lyα EmitteR sYstems (BELLS GALLERY) survey. Seventeen systems are confirmed to be definite lenses with unambiguous evidence of multiple imaging. The lenses are primarily massive early-type galaxies (ETGs) at redshifts of approximately 0.55, while the lensed sources are Lyα emitters (LAEs) at redshifts from two to three. Although most of the lens systems are well fit by smooth lens models consisting of singular isothermal ellipsoids in an external shear field, a thorough exploration of dark substructures in the lens galaxies is required. The Einstein radii of the BELLS GALLERY lenses are, on average, 60% larger than those of the BELLS lenses because of the much higher source redshifts. This will allow for a detailed investigation of the radius evolution of the mass profile in ETGs. With the aid of the average ～13× lensing magnification, the LAEs are frequently resolved into individual star-forming knots with a wide range of properties. They have characteristic sizes from less than 100 pc to several kiloparsecs, rest-frame far-UV apparent AB magnitudes from 29.6 to 24.2, and typical projected separations of 500 pc to 2 kpc.
关键词： galaxies: elliptical and lenticular, cD,gravitational lensing: strong,dark matter,techniques: image processing
更新于2025-09-04 15:30:14
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Expanding the Porphycene Core: Modification and Metalation
摘要： Porphycenes, the first structural isomer of porphyrin, display unique chemical and photophysical properties. In this Account, we detail our group’s individual and collaborative efforts in elucidating further the chemical properties of porphycene. Particular emphasis will be placed on recent efforts devoted to expanding the porphycene core.
关键词： expanded porphycenes,porphycene therapeutics,macrocycles,hetero-annulenes,electronic communication,porphycene materials,porphyrinoid,porphycenes,metal complexes,coordination chemistry,expanded porphyrins
更新于2025-09-04 15:30:14
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Establishment of two ovarian cancer orthotopic xenograft mouse models for in vivo imaging: A comparative study
摘要： Orthotopic tumor animal models are optimal for preclinical research of novel therapeutic interventions. The aim of the present study was to compare two types of ovarian cancer orthotopic xenograft (OCOX) mouse models, i.e. cellular orthotopic injection (COI) and surgical orthotopic implantation (SOI), regarding xenograft formation rate, in vivo imaging, tumor growth and metastasis, and tumor microenvironment. The tumor formation and progression were monitored by bioluminescent in vivo imaging. Cell proliferation and migration abilities were detected by EdU and scratch assays, respectively. Expression of α-SMA, CD34, MMP2, MMP9, vimentin, E-cadherin and Ki67 in tumor samples were detected by immunohistochemistry. As a result, we successfully established COI- and SOI-OCOX mouse models using ovarian cancer cell lines ES2 and SKOV3. The tumor formation rate in the COI and SOI models were 87.5 and 100%, respectively. Suspected tumor cell leakage occurred in 37.5% of the COI models. The SOI xenografts grew faster, held larger primary tumors, and were more metastatic than the COI xenografts. The migration and proliferation properties of the cells that generated SOI xenografts were significantly starker than those deriving COI xenografts in vitro. The tumor cells in SOI xenografts exhibited a mesenchymal phenotype and proliferated more actively than those in the COI xenografts. Additionally, compared with the COI tumors, the SOI tumors contained more cancer associated fibroblasts, matrix metallopeptidase 2 and 9. In conclusion, SOI is a feasible and reliable technique to establish OCOX mouse models mimicking the clinical process of ovarian cancer growth and metastasis, although SOI is more technically difficult and time-consuming than COI.
关键词： ovarian cancer,orthotopic xenograft model,bioluminescence measurements,metastasis,tumor microenvironment
更新于2025-09-04 15:30:14