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11.
The brittle carbonate rock taken from the Tarim Oilfield is tested in laboratory under uniaxial compression. The acoustic emission (AE) is used to monitor the microcracking activity in rock during the experiment. Moreover, the 3D tomograms of carbonate rock after uniaxial compression are obtained by using CT imaging technology, which indicates that microcracks mutually interconnect and eventually form macroscopic fractures after failure. The PFC2D is used to model the behavior of brittle rock including microcracks propagation. The stress–strain curve and cracks distribution in rock model are obtained from the PFC simulation. The numerical results agree with the experimental test well. 相似文献
12.
《高分子科学杂志,A辑:纯化学与应用化学》2013,50(10):1057-1080
Abstract Copolymers involving styrene and homologues of alkyl methacrylates (viz., methyl, ethyl, and butyl methacrylates) were synthesized at 60°C by employing a mixture of n‐butylamine and carbontetrachloride as charge transfer (CT) initiators in dimethyl sulphoxide medium. The CT complex was characterized by UV spectroscopy while the respective copolymers were characterized by employing infrared (IR) and 1H NMR spectroscopy. The copolymer compositions were determined by using 1H NMR spectroscopy and the reactivity ratios were computed by Fineman–Ross (F–R) and Kelen–Tudos (K–T) methods. The reactivity ratios of Sty‐MMA and Sty‐EMA copolymers indicate that higher level of styrene is incorporated in the copolymer. On the other hand the Sty‐BMA system exhibits different behavior. The higher value of r 2 is obtained denoting that BMA is more active than styrene and hence, more BMA is present in the copolymer chain. In Sty‐MMA and Sty‐BMA systems, the product of r 1 and r 2 is greater than 1, representing the formation of high degree of random copolymers. However, in the case of Sty‐EMA, the product of r 1 and r 2 is less than 1 indicating the formation of alternating copolymer. 相似文献
13.
本研究探讨了超声内镜联合CT门静脉成像技术对肝硬化食管胃静脉曲张(GOV)程度及治疗效果的评价价值。选取72例肝硬化GOV患者为研究对象,根据食管静脉曲张套扎术(EVL)治疗效果分为良好组与不良组。结果发现,不良组总横断面表面积、胃左静脉、门静脉、脾静脉、肠系膜上静脉直径及门静脉长度均大于良好组,曲张静脉壁厚度小于良好组(P<0.05);总横断面表面积、胃左静脉、门静脉、脾静脉、肠系膜上静脉直径及门静脉长度与肝功能Child-Pugh分级、静脉曲张程度呈正相关,曲张静脉壁厚度与肝功能Child-Pugh分级、静脉曲张程度呈负相关(P<0.05);总横断面表面积、曲张静脉壁厚度/胃左静脉、门静脉、脾静脉、肠系膜上静脉直径及门静脉长度均为肝硬化GOV患者治疗效果的影响因素(P<0.05);超声内镜、CT门静脉成像参数联合预测肝硬化GOV患者治疗效果的AUC为0.857。可见,超声内镜、CT门静脉成像参数与肝硬化GOV程度、肝功能分级及EVL治疗效果密切相关,可为临床预测EVL治疗效果提供一定参考。 相似文献
14.
E.A. Gusakov O.P. Demidov I.O. Tupaeva E.V. Vetrova M.A. Soldatov A.A. Tereshchenko A.D. Dubonosov Y.A. Sayapin A.V. Metelitsa V.I. Minkin 《Materials Today Chemistry》2021
The first representative of a new class of charge transfer complexes for organic semiconductors was synthesized. The reaction of p-nitroaniline (PNA) with [1,10]-phenanthroline-5,6-dione (PD) results in the formation of a stable molecular charge transfer (CT) complex PNA3-PD2 in a ratio of 3:2. The structure of the molecular CT complex PNA3-PD2 was established by X-ray diffraction studies. Using the density functional theory method, it is shown that several types of intermolecular interactions are realized in the complex: between the PNA amino group and the nitro group of another PNA molecule, carbonyl groups, and PD nitrogen atoms. Complex PNA3-PD2 is stable only in solid form. The diffuse reflectance UV–vis spectrum of PNA3-PD2 crystal powder is characterized by the intense weakly structured long-wavelength absorption band up to 650 nm. Quantum chemical calculations of the electronic structure have shown that the complex PNA3-PD2 is a straight-band semiconductor with a band gap of 2.11 eV. 相似文献
15.
This paper presents a method for the non-destructive inspection and quantitative comparison of low-velocity impact damage in thermoplastic and thermoset composites. X-ray microscope (XRM) computed tomography is used to analyse the three-dimensional internal damage in carbon fibre/poly-ether-ether-ketone (AS4/PEEK) and carbon fibre/epoxy (CCF300/Epoxy) laminates. With the materials and testing conditions used, it was shown that thermoplastic composites have better interlaminar and intralaminar properties, and the following quantitative conclusions were drawn. Under the same impact energy, the maximum contact force of AS4/PEEK laminate was approximately twice that of CCF300/Epoxy laminate. Dissection of the reconstructed XRM volume along a characteristic slicing surface showed that AS4/PEEK had less internal damage than CCF300/epoxy. When the impact energy was 15 J, the XRM results showed that the sum of delamination areas between each ply in AS4/PEEK was only 9% of that in CCF300/Epoxy, whereas the ultrasonic C-scan results showed that the total delamination area of AS4/PEEK was 54.78% of that of CCF300/Epoxy. 相似文献
16.
研究多层CT与DSA对急性冠状动脉综合征患者冠状动脉支架置入术后通畅性及狭窄程度的影响。以我院2017年8月-2018年11月在我院诊断治疗的急性冠脉综合征患者80例作为研究对象,对所有患者进行经皮冠状动脉介入治疗(percutaneous coronary intervention,PCI)手术后,分别进行DSA检查以及64排螺旋CT检查。分析不同检查的冠状动脉狭窄、通畅性之间的差异以及不同检查的一致性。通过对CT检查结果以及DSA检查结果的配对卡方检验,两组患者的检查结果之间的差异不存在统计学意义,两种检查对患者的冠状动脉的狭窄情况诊断一致性较好;两种检查方法对患者的管壁厚度以及管径直径诊断之间的差异不存在统计学意义,两种检验方法对患者的管壁厚度以及管径直径诊断一致性较好。总之,多层CT与DSA对急性冠状动脉综合征患者冠状动脉支架置入术后通畅性及狭窄程度的诊断具有较高的一致性,建议临床推广。 相似文献
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ABSTRACT This study examined the dose and image quality according to the position change of a human phantom in a CT scan. This study used an MDCT 128 Slice CT Scanner instrument. An axial scan was performed with a 16 cm CTDI phantom of a human phantom, and the dose was measured using a pencil chamber meter. The phantom was scanned 10 cm above and below the isocenter and 15 cm above the right and left. The position of the phantom is indicated by C-0 in the isocenter position, S-10 in the upper 10 cm, I-10 in the lower 10 cm, R-15 in the right 15 cm, and L-15 in the left 15 cm. The test was performed 30 times using the brain CT protocol to calculate the dose and the dose width product (DWP). The acquired images were analyzed using the ImageJ program. Statistical analysis was performed using SPSS with one-way ANOVA (p < .05). The mean DWP values of the CT scanner were C-0 31.97 mGy·cm, S-10 24.52 mGy·cm, I-10 24.28 mGy· cm, R-15 17.95 mGy·cm, and L15 17.6 mGy·cm. Compared to the isocenter (C-0), the DLP values measured at each site were 23.3% for S-10, 24% for I-10, 43.8% for R-15, and 44.9% for L15. A significant difference in the one-way ANOVA statistical process was observed (p>0.05). C-0 was measured to be 7.42 HU, S-10 7.87 HU, I-10 8.4 HU, R-15 117 HU, and L-15 13.6 HU for evaluating the image quality. Compared to C-0, S-10 was 5.39%, I-10 was 13.2%, R-15 was 57.6%, and L-15 was 83.2%. The PSNR for S-10, I-10, R-15, and L-15 was 17.37, 17.5, 16.62, and 16.37 dB, respectively. A good quality image can be obtained by positioning the subject precisely in the isocenter in the axial scan, if possible, because the irradiated dose to the subject is low, which can lead to an increase in noise in image reconstruction. 相似文献
20.
The entire gene of carboxyltransferase(CT) domain of acetyl-CoA carboxylase(ACCase) from Chinese Spring wheat(CSW) plastid was cloned firstly, and the 2.3 kb gene was inserted into PET28a^+ vector and expressed in E. coil in a soluble state. The (His)6 fusion protein was identified by SDS-PAGE and Western blot. The recombinant protein was purified by affinity chromatography, and the calculated molecular mass(Mr) was 88000. The results of the sequence analysis indicate that the cloned gene(GeneBank accession No. EU124675) was a supplement and revision of the reported ACCase CT partial cDNA from Chinese Spring wheat plastid. The recombinant protein will be significant for us to investigate the recognizing mechanism between ACCase and herbicides, and further to screen new herbicides. 相似文献