Using the temperature and seepage field-coupling module within COMSOL Multiphysics software, we examined freezing behavior and its evolving patterns in curved underground freezing pipes. This study employed transient states, with the Darcy’s law and porous-media heat-transfer options activated in the Physical Field Interface of the Physical Field and Variable Selection column. The models were created to establish numerical models of freezing reinforcement for both single and multiple pipes with various curvatures. These models were designed to simulate the evolving temperature and seepage fields of soil under diverse freezing conditions. Subsequently, this research utilized the models to simulate the freezing and consolidation conditions of a shallowly buried tunnel within the context of shallow tunnel conditions. The study reveals that after freezing a single pipe using water flow, the change in thickness of the frozen wall in curved pipes is notably smaller than that in straight pipes. This difference is particularly pronounced in the upstream section. Specifically, at a distance of −2000 mm from the main surface, the change in thickness of the frozen wall in straight pipes exceeds that in s = 7 curved pipes by approximately 350 mm. The smaller the long arc ratio s, the greater the arc of the freezing tube and the better the water-blocking effect. In the multi-pipe freezing model, the s = 7 curved pipes exhibit a frozen-wall thickness approximately 120 mm greater than that of straight pipes at a distance of −2000 mm from the main surface. Under the condition of a shallow buried concealed excavation with surging water, a pipe with a long arc ratio s = 7 arc freezing at 46 d attains a permafrost curtain thickness that is equivalent to that achieved by the straight pipe freezing at 58 d. This reduction in thickness shortens the working period by 12 days, resulting in a more efficient process. The successful application of the freezing method in the water-rich aquifer is expected to be a valuable reference for similar projects in the future.
Abstract Colorectal cancer (CRC) is a common digestive tract tumor with the third incidence and death in the world. There is still an urgent need for effective therapeutic targets and prognostic markers for CRC. Herein, we report a novel potential target and marker, Chordin like‐1 (CHRDL1). The function of CHRDL1 has been reported in gastric cancer, breast cancer, and oral squamous cell carcinoma. However, the biological effect of CHRDL1 in CRC remains unrevealed. Transwell and tube formation experiments were used to determine the biological function of CHRDL1. Western blot and rescue experiments were used to determine the specific mechanisms of CHRDL1. Results showed CHRDL1 is significantly downregulated in CRC cell lines and tissues. In vitro, experiments confirmed that CHRDL1 can inhibit cell growth, migration, invasion, angiogenesis and reverse epithelial‐mesenchymal transformation. In vivo, experiments proved that it can inhibit tumor growth and metastasis. Mechanistically, we newly find that CHRDL1 exerts biological functions through the transforming growth factor‐beta (TGF‐β)/vascular endothelial growth factor signaling axis in vitro and in vivo. Therefore, we concluded that CHRDL1 reduces the growth, migration, and angiogenesis of CRC cells by downregulating TGF‐β signaling. Our new findings on CHRDL1 may provide a basis for clinical antiangiogenesis therapy and the prognosis of CRC.
Motivation: Quantitative nidus volume measurement of cerebral arteriovenous malformation（CAVM）is of great important for the CAVM treatment management. Goal(s): This study aims to investigate non-invasive nidus volume measurement of CAVM with silent MRA and explore the difference between silent MRA and TOF-MRA. Approach: Nidus volume was measured by silent MRA, TOF-MRA, and digital subtraction angiography（DSA）. Nidus volume measured by DSA was regarded as golden standard. Results: Silent MRA can accurately measure the nidus volume of CAVM. There is a significant difference in nidus volume measurement between silent MRA and TOF-MRA, silent MRA also has advantage for CAVM patients treated by embolization. Impact: As a non-invasive and contrast agent-free MRA imaging technology, silent MRA can be used as an effective and accurate imaging tool for nidus volume measurement and as a follow-up tool for nidus volume change evaluation after surgery, embolization, and radiotherapy.
Communication performance is one of the most important factors affecting the efficiency of a mobile agent system. The paper studies the communication of a mobile agent system from the viewpoint of performance. We analyze four primary factors that affect the communication performance and propose a communication performance optimization model. The model has three primary functions. First, the model provides a formalism method to describe the communication task of a mobile agent. Second, the model provides a means to make quantitative analysis of the communication performance of a mobile agent system. Third, the model can plan out an optimal communication scheme for mobile agents to minimize the cost of the whole communication. The model could thus be a building block for the optimization of the communication behavior of mobile agents.
This paper has investigated and designed a multi-channel laser focusing transceiver system based on the combination of the laser technology, the space technology and the modern photoelectric detection technology which has the feather of wide wave band, non-chromatic aberration and high quality of image quality etc. The system could be synchronized and can change the distance of detection in a particular direction and obtain the image of atmospheric echo signals at different distances. In this paper we established a multi-channel and variable range laser focusing transceiver system that consists of a single-channel laser focusing transmitter system and a dual-channel receiving telescope system. The three channels of the system depend on the same reference axis. We propose a new method that is capable to improve the laser focusing transceiver system performance. The method is implemented by using parabolic reflector design in the primary and secondary mirror of the variable range laser focusing transmitter system, dual-channel off-axis design in the receiver system and simultaneous imaging design in the different regions of the same CCD target surface of the subsequent imaging system. The detection by two channels using off-axis design would be convenient for computing follow up information. On the base of theoretical basis of the reflective double mirror system and the theory Gaussian beam propagation, this paper calculates the actual converging sot size of the transmitter system and analyzes the wavefront aberration the defocus incidence. The oblique incidence will introduce the certain astigmatism and a small amount of coma and the defocus incidence will produce the certain coma and a small amount of spherical aberration and astigmatism. Finally, an experimental multi-channel laser focusing transceiver system was established and the image quality of the transceiver system on the base of wavefront aberrations, the spot diagram and the MTF curve of some fields is analyzed. Through a lot of experiments, the actual test results are obtained. The wavefront aberrations RMS of the system are 0.079λ,0.0822λ,and 0.0808λ,respectively. The actual test results of the system have met the design requirements which must be better than λ/12=0. 0833.
This paper focuses on evaluating the performance of the Ray-Scan 64 PET/CT system, a newly developed PET/CT in China. It combines a 64 slice helical CT scanner with a high resolution PET scanner based on BGO crystals assembled in 36 rings. The energy window is 350∼ 650 keV, and the coincidence window is set at 12 ns in both 2D and 3D mode. The transaxial field of view (FOV) is 600 mm in diameter, and the axial FOV is 163 mm. Method: Performance measurements were conducted focusing on PET scanners based on NEMA NU-2 2007 standard. We reported the full characterization (spatial resolution, sensitivity, count rate performance, scatter fraction, accuracy of correction, and image quality) in both 2D and 3D mode. In addition, the clinical images from two patients of different types of tumor were presented to further demonstrate this PET/CT system performance in clinical application. Results: using the NEMA NU-2 2007 standard, the main results: (1) the transaxial resolution at 1cm from the gantry center for 2D and 3D was both 4.5mm (FWHM), and at 10cm from the gantry center, the radial (tangential) resolution were 5.6mm (5.3mm) and 5.4mm (5.2mm) in 2D and 3D mode respectively. The axial resolution at 1cm and 10cm off axis was 3.4mm (4.8mm) and 5.5mm (5.8mm) in 2D (3D) mode respectively; (2) the sensitivity for the radial position R0(r=0mm) and R100(r=100mm) were 1.741 kcps/MBq and 1.767 kcps/MBq respectively in 2D mode and 7.157 kcps/MBq and 7.513 kcps/MBq in 3D mode; (3) the scatter fraction was calculated as 18.36% and 42.92% in 2D and 3D mode, respectively; (4) contrast of hot spheres in the image quality phantom in 2D mode was 50.33% (52.87%), 33.34% (40.86%), 20.64% (26.36%), and 10.99% (15.82%), respectively, in N=4 (N=8). Besides, in clinical study, the diameter of lymph tumor was about 2.4 cm, and the diameter of lung cancer was 4.2 cm. This PET/CT system can distinguish the position of cancer easily. Conclusion: The results show that the performance of the newly developed PET/CT system is of high resolution, and low scatter characteristics, and is suitable for clinical applications.
'/%3e%3cuse xlink:href='%23a' transform='rotate(23.036 .093 25.536)'/%3e%3cuse xlink:href='%23a' transform='rotate(45.87 1.273 16.18)'/%3e%3cuse xlink:href='%23a' transform='rotate(69.945 .996 12.078)'/%3e%3cuse xlink:href='%23a' transform='rotate(20.66 -19.689 31.932)'/%3e%3c/svg%3e)
'%3e%3cg id='b'%3e%3cpath id='a' stroke='%23000' stroke-width='2' d='M-6-25H6m-12 3H6m-12 3H6'/%3e%3cuse xlink:href='%23a' y='44'/%3e%3c/g%3e%3cpath stroke='%23fff' d='M0 17v10'/%3e%3ccircle r='12' fill='%23cd2e3a'/%3e%3cpath fill='%230047a0' d='M0-12A6 6 0 0 0 0 0a6 6 0 0 1 0 12 12 12 0 0 1 0-24z'/%3e%3c/g%3e%3cg transform='rotate(-123.69)'%3e%3cuse xlink:href='%23b'/%3e%3cpath stroke='%23fff' d='M0-23.5v3M0 17v3.5m0 3v3'/%3e%3c/g%3e%3c/svg%3e)