基于改进模糊C均值聚类的弥散张量成像图像分割

为了避免随机选取初始聚类中心点的缺陷,利用最大最小距离的方法确定初始聚类中心点.实验结果表明,和传统的模糊C均值聚类(FCM)算法相比,所提聚类算法具有较高的稳定性和准确性,所分割的胼胝体图像边缘信息更加清晰.     

Generalized Intersection Bodies with Parameter

AIn 2005, the classical intersection bodies and L_p intersection bodies were extended. Afterwards, the concept of general L_p intersection bodies and the generalized intersection bodies was introduced. In this paper, we define the generalized bodies with parameter. Besides, we establish the extremal values for volume, Brunn-Minkowski type inequality for radial combination and L_p harmonic Blaschke combination of this notion.     

Solid-phase synthesis of Cu<Subscript>2</Subscript>MoS<Subscript>4</Subscript> nanoparticles for degradation of methyl blue under a halogen-tungsten lamp

The Cu₂MoS₄ nanoparticles were prepared using a relatively simple and convenient solid-phase process, which was applied for the first time. The crystalline structure, morphology, and optical properties of Cu₂MoS₄ nanoparticles were characterized using X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, and UV-vis spectrophotometry. Cu₂MoS₄ nanoparticles having a band gap of 1.66 eV exhibits good photocatalytic activity in the degradation of methylene blue, which indicates that this simple process may be critical to facilitate the cheap production of photocatalysts.     

TTAC-HPMo/SiO_2催化剂的表征及其氧化脱硫性能分析

以十四烷基三甲基氯化铵(TTAC)为模板剂,正硅酸乙酯(TEOS)为硅源,采用溶胶-凝胶法制备TTAC-HPMo/SiO_2催化剂,利用FTIR、XRD、SEM和N_2吸附-脱附等技术对其进行表征,并分析催化剂制备条件和反应条件对模型油氧化脱硫性能的影响。结果表明,在m(HPMo)/m(SiO_2)=15%、焙烧温度为400℃条件下所制TTAC-HPMo/SiO_2催化剂,其孔隙结构发达、氧化脱硫性能最佳;对于10mL以二苯并噻吩(DBT)为目标含硫化合物的模型油(硫含量为400μg/g),当m(TTAC-HPMo/SiO_2)/m(模型油)=0.43%、V(H_2O_2)/V(模型油)=0.2%、反应温度为60℃、反应时间为14min时,所制TTAC-HPMo/SiO_2催化剂对模型油中DBT的脱除率达到100%。     

分级多孔纳米炭纤维的结构及电容性能

以酚醛树脂为碳源、PVP为纺丝助剂、纳米MgO颗粒为模板剂,通过静电纺丝法制得酚醛树脂基纳米炭纤维,经过炭化、KOH活化、酸洗后得到分级多孔纳米炭纤维,利用SEM、XRD、XPS、拉曼光谱仪及氮气吸脱附实验,对所制多孔纳米炭纤维的结构和形貌进行表征,并将其作为模拟电容器的电极,利用循环伏安、恒电流充放电及交流阻抗方法测试了材料的电化学性能。结果表明,KOH活化引入了数量可观的微孔,所得纳米炭纤维表现出明显的"微孔-中孔-大孔"分级孔分布的特点,其比表面积达到1058.4m~2/g,总孔容为1.64cm~3/g。电化学测试结果表明,所制分级多孔纳米炭纤维在6mol/L KOH电解液中显示出优异的电容性能,在0.2A/g的电流密度下,其放电比容量达到198F/g,在20A/g电流密度下,电容保持率达到65%。     

Nb微合金化对低合金高强钢耐海水腐蚀性能的影响

利用室内模拟海水加速腐蚀试验及电化学分析,研究了Nb微合金化对Cu-Cr-Ni-P系低合金高强钢耐海水腐蚀性能的影响。结果表明,含Nb钢与不含Nb钢组织均由铁素体和珠光体构成,但Nb微合金化后钢中珠光体组织减少且晶粒细化明显,其在模拟海水介质中的平均腐蚀速率与不含Nb钢相比,降低了约12%,阳极腐蚀电流密度也有所降低。由此可见,在Cu-Cr-Ni-P系低合金高强钢中加入Nb元素有助于提高其耐海水腐蚀性能。     

Effects of Zn content on the microstructure and the mechanical and corrosion properties of as-cast low-alloyed Mg–Zn–Ca alloys

The effects of Zn content on the microstructure and the mechanical and corrosion properties of as-cast low-alloyed Mg–xZn–0.2Ca alloys (x=0.6wt%, 2.0wt%, 2.5wt%, hereafter denoted as 0.6Zn, 2.0Zn, and 2.5Zn alloys, respectively) are investigated. The results show that the Zn content not only influences grain refinement but also induces different phase precipitation behaviors. The as-cast microstructure of the 0.6Zn alloy is composed of α-Mg, Mg₂Ca, and Ca₂Mg₆Zn₃ phases, whereas 2.0Zn and 2.5Zn alloys only contain α-Mg and Ca₂Mg₆Zn₃ phases, as revealed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses. Moreover, with increasing Zn content, both the ultimate tensile strength (UTS) and the elongation to fracture first increase and then decrease. Among the three investigated alloys, the largest UTS (178 MPa) and the highest elongation to fracture (6.5%) are obtained for the 2.0Zn alloy. In addition, the corrosion rate increases with increasing Zn content. This paper provides an updated investigation of the alloy composition–microstructure–property relationships of different Zn-containing Mg–Zn–Ca alloys.     

Effect of particle size distribution on the microstructure,texture,and mechanical properties of Al–Mg–Si–Cu alloy

The effect of particle size distribution on the microstructure,texture,and mechanical properties of Al–Mg–Si–Cu alloy was investigated on the basis of the mechanical properties,microstructure,and texture of the alloy.The results show that the particle size distribution influences the microstructure and the final mechanical properties but only slightly influences the recrystallization texture.After the pre-aging treatment and natural aging treatment(T4 P treatment),in contrast to the sheet with a uniform particle size distribution,the sheet with a bimodal particle size distribution of large constituent particles and small dispersoids exhibits higher strength and a somewhat lower plastic strain ratio(r) and strain hardening exponent(n).After solution treatment,the sheet with a bimodal particle size distribution of large constituent particles and small dispersoids possesses a finer and slightly elongated grain structure compared with the sheet with a uniform particle size distribution.Additionally,they possess almost identical weak recrystallization textures,and their textures are dominated by CubeND {001}310 and P {011}122 orientations.     

Morphology and quantitative analysis of O phase during heat treatment of hot-deformed Ti_2AlNb-based alloy

A 1040°C-hot-deformed Ti_2AlNb-based alloy solution-treated at 950°C and aged at different temperatures was quantitatively investigated. The microstructure, size of the phase, and microhardness of the deformed alloys were measured. The results indicated that the microstructure of the deformed Ti_2AlNb-based alloy specimens comprise coarse O lath, fine O lath, equiaxed O/α_2, and acicular O phase. More O phase was generated in the deformed alloy after heat treatment because the acicular O phase was more likely to nucleate and grow along the deformation-induced crystal defects such as dislocations and subgrain boundaries. After deformation and subsequent heat treatment, the acicular O phase of the resultant alloy became finer compared to that of the undeformed alloy, and the acicular O phase became coarser and longer with the elevated aging temperature, while the width of the O lath exhibited unobvious variations. The hot deformation facilitated the dissolution of the O lath but accelerated the precipitation of the acicular O phase. When the 950°C-solution-treated deformed Ti_2AlNb-based alloy was then aged at 750°C for different periods, the phase content was nearly invariable, O and B2 phases eventually reached equilibrium, and the microstructure became stable and homogeneous.     

Developing anti-neoplastic biotherapeutics against eIF4F

Biotherapeutics have revolutionized modern medicine by providing medicines that would not have been possible with small molecules. With respect to cancer therapies, this represents the current sector of the pharmaceutical industry having the largest therapeutic impact, as exemplified by the development of recombinant antibodies and cell-based therapies. In cancer, one of the most common regulatory alterations is the perturbation of translational control. Among these, changes in eukaryotic initiation factor 4F (eIF4F) are associated with tumor initiation, progression, and drug resistance in a number of settings. This, coupled with the fact that systemic suppression of eIF4F appears well tolerated, indicates that therapeutic agents targeting eIF4F hold much therapeutic potential. Here, we discuss opportunities offered by biologicals for this purpose.