The assessment of cerebral blood flow (CBF) is crucial in the evaluation of intracranial atherosclerotic disease. This study was performed to compare single postlabeling delay (PLD) 3-dimensional pseudo-continuous arterial spin labeling (3D-pCASL) and 7-delay 3D-pCASL magnetic resonance imaging in patients with intracranial atherosclerotic stenosis.A total of 26 patients with moderate to severe atherosclerotic stenosis or occlusion of an intracranial artery were prospectively enrolled in the study. Perfusion parameters were obtained in various regions of interest (ROIs), namely CBF for single PLDs of 1,525 ms (CBF1525 ms), 2,025 ms (CBF2025 ms), and 2,525 ms (CBF2525 ms) with 3D-pCASL, as well as arterial transit time (ATT) and transit-corrected CBF (CBFtransit-corrected) for 7-delay 3D-pCASL. The consistency of the perfusion parameters between single-PLD 3D-pCASL and 7-delay 3D-pCASL was investigated, and the relationship between vascular stenosis and perfusion parameters was explored.Bland-Altman plots compared the CBF values derived from single-PLD 3D-pCASL to those from CBFtransit-corrected. ATT significantly correlated with the difference between CBFtransit-corrected and CBF1525 ms, CBF2025 ms, and CBF2525 ms, respectively (P<0.05). Binary logistic regression analysis revealed that the CBFtransit-corrected and ATT correlated with the presence of moderate or more severe stenotic vascular territories (P<0.05).The single-PLD 3D-pCASL and the 7-delay 3D-pCASL showed inconsistencies in the assessment of CBF, and the perfusion parameters generated under the standard single-PLD 3D-pCASL were more affected by ATT. Moreover, CBFtransit-corrected and ATT were consistent with stenotic vascular territories, which is useful in the evaluation of intracranial atherosclerotic disease.
The management technology of probabilistic XML database become today's research focus with XML being the standards of information representation and data exchange on the internet and uncertain data existing in various fields.A variety of probabilistic XML data models are proposed basing on the type of probabilistic data and the need of solving practical problem.First,the concepts,characteristics and challenges in probabilistic XML data management are introduced.Second,the advance of the research on probabilistic XML data,probabilistic XML data model are proposed,the core idea of these models comes from the possible world model,a possible world instance can be got by selecting the child node and deleting nodes and the sum of the probabilities for all the instances is 1.Finally,translation among models are given.The theory laid the foundation for the probabilistic XML database queries,normalization theory.
From the point of view of engineering application and taken position errors of FOG strapdown inertial integrated surveying system as observed variables,system error model is introduced.Based on Monte-Carlo method,the simulation of SINS/cable length integrated surveying system is studied.The simulation indicates that a good agreement and accuracy of measurement meet the requirement of engineering by using FOGS and accelerometers of medium precision under the condition of the cable length's second level renew.The accuracy of the azimuth measurement is less than 1°,and the accuracy of the measurement for inclination angle is less than 0.1°.
African swine fever (ASF) is one of the most severe infectious diseases of pigs. In this study, a LAMP assay coupled with the CRISPR Cas12a system was established in one tube for the detection of the ASFV p72 gene. The single-strand DNA-fluorophore-quencher (ssDNA-FQ) reporter and CRISPR-derived RNA (crRNAs) were screened and selected for the CRISPR detection system. In combination with LAMP amplification assay, the detection limit for the LAMP-CRISPR assay can reach 7 copies/μl of p72 gene per reaction. Furthermore, this method displays no cross-reactivity with other porcine DNA or RNA viruses. The performance of the LAMP-CRISPR assay was compared with real-time qPCR tests for clinical samples, a good consistency between the LAMP-CRISPR assay and real-time qPCR was observed. The method shed a light on the convenient, portable, low cost, highly sensitive and specific detection of ASFV, demonstrating a great application potential for monitoring on-site ASFV in the field.
In this work, the ablation characteristic, surface structure, and wetting property of the femtosecond laser-processed copper (Cu) surface are systematically studied. With the increase of laser pulse number, the area of the ablation crater increases and then tends to be stable, the period (0.62λ ∼ λ) of the generated ripple structures decreases, and the area of the periodic ripple structures in the Cu ablation crater first increases and then decreases. With the increase in laser fluence, the area of the ablation crater slightly increases, the period of the generated ripple structures varies oscillatively, and the area of the periodic ripple structures in the Cu ablation craters increases. Different columnar structures on the Cu surface are obtained through femtosecond laser cross-scanning processing. The height of columnar structures basically increases with the increase in laser power, laser scanning times, and laser scanning spacing. The wetting properties of the Cu columnar structure surfaces are also investigated. It reveals that the droplet contact angle obviously decreases with the increase in laser power and laser scanning times, and increases with the increase in laser scanning spacing. The variation of droplet contact angle on the laser-processed Cu surface is attributed to the different columnar structures and their different heights. It also reveals that the Cu surface changes from original hydrophobic to superhydrophilic with a contact angle of 8.9°. This work indicates the ability of femtosecond laser processing in regulating micro/nanostructure and wetting property of the Cu surface, which can be applicable to the surface treatment and performance control of other metallic materials.
Carbon fiber reinforced polymer (CFRP), a highly engineered lightweight material with superior properties, is widely used in industrial fields, such as aerospace, automobile, and railway transportation, as well as medical implants and supercapacitor. This work presents an effective surface treatment method for the controllable fabrication of hydrophilic surface micro/nanostructures of CFRP through femtosecond laser processing. Selective removal of the epoxy resin and leaving the carbon fibers exposed are achieved when CFRP is weakly ablated by a femtosecond laser. The diameters and structures of the carbon fibers can be controlled by adjusting the laser processing parameters. Three-dimensional surface micro/nanostructures are processed when CFRP is strongly ablated by a femtosecond laser. Meanwhile, the transformation of the sp2 orbitals to sp3 orbitals of graphitic carbons of carbon fibers is induced by a femtosecond laser. Moreover, the investigation of surface roughness and wettability of femtosecond laser-processed CFRP indicates increased roughness and excellent hydrophilicity (a contact angle of 28.1°). This work reveals the effect of femtosecond laser processing on the regulation of the physicochemical properties of CFRP, which can be applicable to surface treatment and performance control of other fiber-resin composites. The excellent hydrophilicity will be conducive to the combination of CFRP with other materials or to reducing the friction resistance of CFRP used in medical implants.
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