多层螺旋CT增强扫描结合后重建技术在结肠肿瘤性肠梗阻的临床应用价值分析

目的:探讨多层螺旋CT增强扫描结合后重建技术在结肠肿瘤性肠梗阻的临床应用价值分析。方法:选取2019年3月-2020年4月我院收治的结肠肿瘤性肠梗阻患者80例,患者均采用常规X线进行检查,并同时采用多层螺旋CT进行扫描检查,检查后采用重建技术进行病患病理分析,观察患者多层螺旋CT增强扫描结合重建技术对结肠肿瘤性肠梗阻的临床价值。结果:患者均为确诊肠梗阻患者,经CT诊断患者其诊断准确率(100.00%)优于X线诊断准确率(73.75%),其数据差异具有统计学意义(P<0.05);在采用多层螺旋CT诊断中,有78例通过病理诊断或者内镜活检与梗阻部位结果一致,其诊断准确率为97.50%。在患者采用多层螺旋CT增强扫描结合后重建技术,有71例诊断结果与上述肠梗阻诊断结果保持一致,其诊断准确率为88.75%。结论:多层螺旋CT和重建技术的应用,可以准确诊断出肠梗阻的病灶部位以及病因等,有效提高临床诊断准确率,对肠梗阻的治疗有重要意义。

CT平扫结合增强扫描在肝左叶癌鉴别诊断中的价值分析

目的探讨CT平扫结合增强扫描在肝左叶癌鉴别诊断中的价值分析。方法回顾性地分析我院2014年1月-2015年12月期间接收的48例肝左叶癌患者的检查资料,通过CT平扫结合增强扫描得出的肝左叶癌的病灶影像特点,对CT平扫结合增强扫描在肝左叶癌鉴别诊断中的价值分析。结果本文共48例患者,通过CT平扫结合增强扫描确诊左叶癌患者发生肝内转移的患者33例(占总人数的68.75%);发生腰椎转移的15例(占总人数的31.25%),通过增强扫描,可见肝左叶病灶无强化,边界清晰,低密度小结节影为病灶转移灶。结论CT平扫结合增强扫描能够清晰反映病灶转移的位置,CT扫描结果和患者的临床病例特征基本吻合,诊断的准确率达到90%的水平,具有极高的临床应用价值。

多扫描仪结合在塑石表面积测量中的应用与分析

针对地面三维激光扫描技术应用于塑石假山表面积测量中的精度问题,本文采用3台不同型号的三维激光扫描仪进行不规则物体表面积测量实验,通过分析实验数据,验证了三维激光扫描技术应用于不规则物体高精度表面积测量的可行性,确定了达到工程精度要求的仪器扫描分辨率及不同仪器的结合使用方案;通过高精度塑石假山表面积测量工程应用,阐述了项目内外业工作流程及重难点,为结合不同扫描仪在表面积测量中的应用提供参考。

双波长激光共聚焦生物芯片扫描仪的研制

生物芯片扫描仪是生物芯片技术应用中的关键仪器,激光共聚焦成像的原理,着重介绍一种光学扫描和机械扫描相结合的双波长激光共聚焦生物芯片扫描仪,在保证分辨力、灵敏度等重要性能指标的前提下提高了扫描速度和扫描效率,最后对系统性能做了简要分析。

非同轴激光雷达重叠因子的自校正系统设计

受振动,温度,预紧力变化等外部环境因素影响,激光雷达系统的激光发射光轴和望远镜接收光轴会发生变化,导致激光雷达系统的重叠因子发生变化,进而影响激光雷达系统的远场探测精度与探测稳定性。针对非同轴激光雷达提出开展重叠因子自校正的软硬件系统设计,采用二相电机驱动,具有自锁功能的蜗轮蜗杆发射光轴较正平台设计并搭建了激光发射光轴倾角调节系统,并以激光回波信号强度为校正判据寻找非同轴激光雷达系统收发光轴的最佳匹配位置。自校正过程采用粗扫描和细扫描相结合的方式,以实现校正精度和校正效率的综合考量,其中粗扫描采用环形扫时序,可在961 s内将激光发射光轴锁定在0.4 mrad×0.4 mrad倾角范围内;细扫描采用S形时序,可在441 s内实现激光发射光轴0.02 mrad的倾角调节精度。自校正前后的大气回波距离平方修正信号表明,设计的自校正系统能够实现非同轴激光雷达系统重叠因子的有效校正,并提升系统探测性能,为全天时,无人值守的激光雷达大气探测提供支持。

功能影像学在结直肠癌腹膜转移瘤中应用的研究进展

结直肠癌患者伴发腹膜转移瘤(peritoneal metastases,PM)是常见的死亡原因之一,准确的术前评估及是否手术治疗的选择决定了患者的预后。多层螺旋计算机断层扫描(multi-slice computed tomography,MSCT)评估结直肠癌的PM具有局限性,因此考虑通过其他影像学成像方法来优化治疗方案的选择。本文除了常规MSCT外,还综述了几种功能影像学方法在结直肠癌PM评估中的作用,包括扩散加权MRI、正电子发射断层扫描结合计算机断层扫描、正电子发射断层扫描结合MRI和分子影像学,本文详细阐述了上述功能影像学方法在预测结直肠癌PM手术结果、评估治疗反应及监测肿瘤复发方面的应用和优缺点。

应用血管内超声/光学相干断层成像杂交技术研究冠状动脉钙化与斑块回缩的关系

目的:冠状动脉钙化是否与斑块回缩相关尚不清楚。本研究的目的是结合光学相干断层扫描(OCT)和血管内超声(IVUS)评估冠状动脉钙化和斑块回缩(PS)之间的关系。方法:15例患者,16支血管纳入本研究,术后即刻和术后5年联合应用OCT和IVUS评估钙化斑块面积变化和斑块回缩,及二者之间的关系。IVUS检测管腔面积(LA)、血管面积(VA)和斑块/中膜面积(PA)。将斑块/中层回缩(PS)定义为PA相对减少>5%。OCT检测钙化面积、钙化弧度和钙化长度。结果:术后即刻和5年随访时,共有72个OCT和IVUS完全匹配的横断面(共432个图)纳入该研究。72个横截面中,35个横截面在5年随访时显示为PS,37个横截面为非PS。斑块面积的变化分别与OCT测量的钙化面积变化呈负相关(r=-0.29,P=0.004),与OCT钙化弧度变化(r=-0.42,P<0.001),OCT钙化长度变化(r=-0.5,P<0.001)呈负相关,与IVUS测量的钙化弧度变化呈负相关(r=-0.31,P=0.024),而与管腔面积变化呈正相关(r=0.24,P=0.044)。结论:冠状动脉钙化斑块进展使得斑块回缩和管腔扩大。应用IVUS/OCT杂交技术能更好的评估钙化斑块进展和斑块回缩之间的相关性。

气管粘液嵌塞的放射诊断分析

目的:对支气管黏液嵌塞临床表现进行探讨,以提高对此疾病的认识。方法:接受后前位高千伏胸片的患者共30例。其中,接受胸部的CT扫描的有15例,接受HRCT(高分辨率CT)扫描的有4例。咯出粘液栓患者有22例;经手术的病理证实,肺癌合并支气管粘液嵌塞患者5例;粘液栓通过支气管镜取出的患者1例。结果:X线平片上,支气管粘液栓多数呈树枝状(20/30),仅1例出现肺不张现象。支气管粘液嵌塞据CT显示多数也都是树枝状(9/15)。支气管粘液栓在X线和CT片上的显著特点为主轴同支气管走向相同,方向都是指向肺门,伴随着支气管的扩张。结论:X线平片与CT扫描结合是一种支气管粘液嵌塞发现与诊断的好方法。

Effects of combined addition of Y and Ca on microstructure and mechanical properties of die casting AZ91 alloy

A series of die casting heat-resistant magnesium alloys based on Mg-Al system were developed for automotive application by adding Y and various amounts of Ca. The mechanical properties and microstructures of die casting AZ91 alloy with combined addition of Y and Ca were investigated by optical microscopy, scanning electronic microscopy, X-ray diffractometry and mechanical property test. The results show that the combined addition of Y and Ca can refine the as-die-cast microstructure, result in the formation of Al2Ca phase and Al2Y phase, and inhibit the precipitation of Mg17Al12 phase. The combined addition of Y and small amount of Ca has little influence on the ambient temperature tensile properties, but increasing the content of Ca can improve significantly the tensile strength at both ambient and elevated temperatures. It is found that for AZ91-1Y-xCa alloy, the hardness and the elevated temperature tensile strength increase, while the elongation decreases with increasing the addition of Ca. The mechanism of mechanical properties improvement caused by the combined addition of Y and Ca was also discussed.

Theoretical Investigating Mechanisms of Drug-Resistance Generated by Mutation-Induced Changes in Influenza Viruses

Influenza A(A/H_(x)N_(y))is a significant public health concern due to its high infectiousness and mortality.Neuraminidase,which interacts with sialic acid(SIA)in host cells,has become an essential target since its highly conserved catalytic center structure,while resistance mutations have already generated.Here,a detailed investigation of the drug resistance mechanism caused by mutations was performed for subtype N9(A/H7N9).Molecular dynamics simulation and alanine-scanning-interaction-entropy method(ASIE)were used to explore the critical differences between N9 and Zanamivir(ZMR)before and after R294K mutation.The results showed that the mutation caused the hydrogen bond between Arg294 and ZMR to break,then the hydrogen bonding network was disrupted,leading to weakened binding ability and resistance.While in wild type(A/H7N9^(WT)),this hydrogen bond was initially stable.Meanwhile,N9 derived from A/H11N9 was obtained as an R292K mutation.Then the relative binding free energy of N9 with five inhibitors(SIA,DAN,ZMR,G28,and G39)was predicted,basically consistent with experimental values,indicating that the calculated results were reliable by ASIE.In addition,Arg292 and Tyr406 were hot spots in the A/H11N9^(WT)-drugs.However,Lys292 was not observed as a favorable contributing residue in A/H11N9^(R292K),which may promote resistance.In comparison,Tyr406 remained the hotspot feature when SIA,ZMR,and G28 binding to A/H11N9^(R292K).Combining the two groups,we speculate that the resistance was mainly caused by the disruption of the hydrogen bonding network and the transformation of hotspots.This study could guide novel drug delivery of drug-resistant mutations in the treatment of A/H_(x)N9.

Effect of ultrasonic field on microstructure and mechanical properties of as-cast 7085 aluminum alloy

The effect of an ultrasonic field on the microstructure and mechanical properties of 7085 aluminum alloy during solidification was investigated by optical microscopy, Vickers hardness test, tensile test, scanning electron microscopy （SEM） with energy dispersive X-ray spectrometry, and electron probe micro-analysis （EPMA）. The results showed that the grains of aluminum alloy were significantly refined and secondary phases were dispersed and distributed uniformly at the grain boundaries, due to ultrasonic treatment （UST）. By EPMA, it was observed that the distribution of the main elements A1, Zn, Mg and Cu was more homogeneous in alloys with UST, than in alloys without UST. The mechanical properties of the aluminum alloy also significantly improved. As demonstrated by the SEM fractography of the fractured faces of several castings, fracture of the unrefined specimens occurred in a brittle manner, whereas the cracks of the refined specimens showed quasi-cleavage fracture.

Effect Mechanism of Structure-Changed Water on Heat Stability of Lysozyme

Based on the mechanism of the effect of hydration on the heat stability of lysozyme and the theory of water molecule clusters, the effect of structure-changed water on heat stability of lysozyme has been studied. The results obtained by differential scanning calorimetry (DSC) showed that the thermal denaturation temperature of lysozyme had been elevated 8.47 K through hydration of lysozyme with processed water whose structure had been changed so it was called "structured water" compared to ordinary water. The reason is that structured water changed the dipole moment of water molecules and easily formed cyclic water hexamer or cage-like water hexamer, so that the interacting force of maintaining three-dimensional conformation of lysozyme could be reinforced.

Microstructure and corrosion resistance of sputtered TiN coatings on surface of Zr-4 alloy

To improve the oxidation resistance and corrosion resistance of Zr-4 alloy, titanium nitride （TIN） coatings were prepared on the Zr-4 alloy with a TiN ceramic target with different ratios of N2. Microstructure and high-temperature properties of the TiN coated samples were studied by scanning electron microscopy （SEM）, energy dispersive spectrometer （EDS）, X-ray diffraction meter （XRD）, X-ray photoelectron spectroscopy （XPS）, heat treatment furnace and autoclaves, respectively. The x value of the TiN coatings （TiN） ranges from 0.96 to 1.33. After the introduction of N2, TiN coating exhibits a weak （200） plane and a preferred （111） orientation. The coating prepared with an N2 flow ratio of 15% shows an optimal oxidation resistance in the atmospheric environment at 800 ℃. In either 1 200 ℃ steam environment for one hour, or deionized water at 360 ℃ and a pressure of 18.6 Mpa for 16 d, the opitimized TiN coated samples have no delamination or spallation; and the gains in the masses of samples are much smaller than Zr-4 alloy. These results demonstrate the effectiveness of the optimized TiN coating as the protective coating on the Zr-4 alloy under extreme conditons.

Correlation between microstructural features and tensile strength for friction welded joints of AA-7005 aluminum alloy

Similar friction welded joints of AA-7005 aluminum rods were fabricated using different combinations of process parameters such as friction pressure(1.0, 1.5 and 2.0 MPa) and friction time(10, 15 and 20 s). Interfacial microstructure and formation of intermetallic compounds at the joint interface were evaluated via scanning electron microscopy(SEM) equipped with energy dispersive spectrum(EDS), and optical microscopy(OM). Microstructural observations reveal the formation of intermetallic phases during the welding process which cannot be extruded from the interface. Theses phases influence the tensile strength of the resultant joints. From the tensile characteristics viewpoint, the greatest tensile strength value of 365 MPa is obtained at 1.5 MPa and 15 s. Finally, the role of microstructural features on tensile strength of resultant joints is discussed.

Electrochemical performance of Ti^(4+)-doped LiFePO_4 synthesized by co-precipitation and post-sintering method

Ti4+-mixed FePO4·xH2O precursor was prepared by co-precipitation method,with which Ti4+ cations were added in the process of preparing FePO4·xH2O to pursue an effective and homogenous doping way.Ti4+-doped LiFePO4 was prepared by an ambient-reduction and post-sintering method using the as-prepared precursor,Li2CO3 and oxalic acid as raw materials.The samples were characterized by scanning electron microscopy (SEM),X-ray diffractometry (XRD),electrochemical impedance spectroscopy (EIS),and electrochemical charge/discharge test.Effects of Ti4+-doping and sintering temperature on the physical and electrochemical performance of LiFePO4 powders were investigated.It is noted that Ti4+-doping can improve the electrochemical performance of LiFePO4 remarkably.The Ti4+-doped sample sintered at 600 ℃ delivers an initial discharge capacity of 150,130 and 125 mA·h/g with 0.1C,1C and 2C rates,respectively,without fading after 40 cycles.

Corrosion protection of composite coating combining ceramic layer,copper layer and benzotriazole layer on magnesium alloy

A novel composite coating was fabricated on AZ91 magnesium alloy by applying a composite surface treatment which combined the methods of plasma electrolytic oxidation(PEO)pre-treatment,electroless copper and benzotriazole(BTA)passivation. The cross-section microstructures and chemical compositions of coating were examined using scanning electron microscopy(SEM) equipped with energy dispersive analysis of X-rays(EDX).Potentiodynamic polarization curves and salt spray tests were employed to evaluate corrosion protection of the coating to substrate in 5%NaCl solution.It is indicated that electroless copper produces a rough interface between the electroless copper layer and the ceramic layer.The corrosion potential shifts to the positive direction significantly and the current density decreases by more than one order of magnitude.There is no visible galvanic corrosion pits on the surface of the composite coating combination of PEO and electroless copper after 168 h neutral salt spray testing.The color of copper after BTA immersion could be held more than 60 d.

Organic-magnesium complex conversion coating on AZ91D magnesium alloy

An organic-magnesium complex conversion(OMCC)coating on AZ91D magnesium alloy was obtained by treating in a solution containing organic compounds.SEM,FESEM and XPS were used to examine the surface morphology,thickness and structure of the conversion coatings.The results show that the continuous and uniform conversion coating is deposited on AZ91D alloy and the main component of the coatings is organic compound containing benzene ring,which forms a chemical bond with magnesium.The polarization measurement and salt spray test show that the corrosion resistance of the conversion coating is much higher than that of traditional chromate conversion coating.

^(27)Al MAS-NMR study of inorganic polymer formation at ambient temperature

Inorganic polymers are a novel class of materials formed by the polymerization of silicon, aluminium and oxygen species to form an amorphous three-dimensional framework structure. The basis of this process is the alkaline solutions to induce a certain amount of Si and AI atoms to dissolve from a feedstock such as aluminosilicate. A study of 27A1 MAS-NMR was carried out in an attempt to understand the reaction mechanism of the inorganic polymerization at ambient temperature. Scanning electron microscopy （SEM） and X-ray diflYactometry （XRD） were also employed to establish the composition and microstructure of the inorganic polymerization. Specimens were prepared with different A1/Si mole ratios from the starting materials. The higher the AI content, the more sufficient the AI atoms that can combine with SiO4, and the longer the reaction time, the more the bonded Si--O--A1--O polymer structure, and then the higher the A1 content, the fewer the octahedral A1 with a uniform Si--O--A1--O structure in four directions, because four AI atoms are combined with SiO4, resulting in a uniform Si--O--AI--O structure in four directions. The results show that they have an amorphous microstructure.

Synthesis of poly（lactide-co-glycolide） with high viscosity-average molecular weight

In the present paper, poly（lactide-co-glycolide） （PLGA） with high viscosity-average molecular weight was fabricated with L-lactide （LLA） and glycolide （GA） as monomers via opening-ring polymerization. Fourier transform Infrared （FTIR） spectroscopy, ~H-NMR, X-ray diffraction （XRD） and scanning electron microscopy （SEM） were applied to characterize the products. Viscosity method was used to determine the viscosity-average molecular weight of the PLGA copolymers. Moreover, the mechanical strength of PLGA was investigated. The results showed that the highly pure LLA and GA were prepared. The as-fabricated PLGA was typical semicrystalline copolymer with the crystallinity of 18.72%. Both viscosity-average molecular weight and mechanical strength of PLGA decreased gradually with the increase of GA content. In addition, the higher the viscosity-average molecular weight was, the more the microcracks and holes on the cross-section of PLGA copolymer materials were, the smoother the cross-sections were.

Fracture toughness of multiphase TiAl-Nb alloy in situ consolidated by spark plasma sintering

A fine-grained TiAl alloy with a composition of Ti-45Al-5Nb-1.5Cr-0.2W （mole fraction, %） with multiphases was prepared by spark plasma sintering （SPS） and heat-treating at 1 100 ℃ for 48 h. The relationship among sintering temperature, microstructure and fracture toughness were investigated by X-ray diffractometry （XRD）, optical microscopy （OM）, scanning electron microscopy （SEM） and mechanical testing. The results show that microstructure of the bulk alloy depends on the sintering temperature strongly, and the main phase TiAl and few phases Ti3Al and niobium solid solution （Nbss） are observed in the SPS bulk samples. In the heat-treatment condition, the lamellar and Nbss phase can provide significant toughening by plastic strengthening, interface decohension, crack branch and crack bridge mechanisms. The fracture mode of the SPS TiAl composite samples is intergranular rupture and cleavage fracture.