Effect of Mo content on the thermal stability of Ti-Mo-bearing ferritic steel

The effects of tempering holding time at 700℃on the morphology,mechanical properties,and behavior of nanoparticles in Ti-Mo ferritic steel with different Mo contents were analyzed using scanning electron microscopy and transmission electron microscopy.The equilibrium solid solution amounts of Mo,Ti,and C in ferritic steel at various temperatures were calculated,and changes in the sizes of nanoparticles over time at different Mo contents were analyzed.The experimental results and theoretical calculations were in good agreement with each other and showed that the size of nanoparticles in middle Mo content nano-ferrite(MNF)steel changed the least during aging.High Mo contents inhibited the maturation and growth of nanoparticles,but no obvious inhibitory effect was observed when the Mo content exceeded 0.37wt%.The tensile strength and yield strength continuously decreased with the tempering time.Analysis of the strengthening and toughening mechanisms showed that the different mechanical properties among the three different Mo content experiment steels were mainly determined by grain refinement strengthening(the difference range was 30-40 MPa)and precipitation strengthening(the difference range was 78-127 MPa).MNF steel displayed an ideal chemical ratio and the highest thermodynamic stability,whereas low Mo content nano-ferrite(LNF)steel and high Mo content nano-ferrite(HNF)steel displayed relatively similar thermodynamic stabilities.     

Bounds for the Least Laplacian Eigenvalue of a Signed Graph

A signed graph is a graph with a sign attached to each edge. This paper extends some fundamental concepts of the Laplacian matrices from graphs to signed graphs. In particular, the relationships between the least Laplacian eigenvalue and the unbalancedness of a signed graph are investigated.     

对西方数学直观的评析

本文从数学方法论的角度,具体论述和评析了西方数学直观随数学发展的不同阶段所表现出的特点和演变方式。     

谈经济数学教学过程的优化

经济数学教学过程的优化要以系统教学理论为指导，树立全局意识、创新意识、应用意识和质量意识。     

An Improved Synthesis of Retinoic Acid from β-Ionone

A convenient and large-scale preparation of retinoic acid 1 from β-ionone in five steps with 38% overall yield is described.The key steps are the epoxidization of 2 with a new methylated agent and the condensation 4 with tetraethyl methylenediphophonate in one-pot procedure to prepare 6.     

An Extension Landau-Lifshitz Model in Studying Soft Ferromagnetic Films

In this paper, we propose a model in studying soft ferromagnetic films, which is readily accessible experimentally. By using penalty approximation and compensated compactness, we prove that the dynamical equation in thin film has a local weak solution. Moreover, the corresponding linear equation is also dealt with in great detail.     

HELITOW

ＨＥＬＩＴＯＷＨｅｌｉＴＯＷ系统是在侦察／援救直升机反安装的ＳａａｂＨｅｌｉｏｓ观察系统基础上研制的。该系统有×３和×１２两种放大率，光学系统（英国ＰｉｌｋｉｎｇｔｏｎＯｐｔｒｏｎｉｃｓ研制）分辨率和稳定精度都比较高。伸进舱内的目镜臂不用时能紧贴舱顶...     

A microfluidic device using a green organic light emitting diode as an integrated excitation source

A simply fabricated microfluidic device using a green organic light emitting diode (OLED) and thin film interference filter as integrated excitation source is presented and applied to fluorescence detection of proteins. A layer-by-layer compact system consisting of glass/PDMS microchip, pinhole, excitation filter and OLED is designed and equipped with a coaxial optical fiber and for fluorescence detection a 300 microm thick excitation filter is employed for eliminating nearly 80% of the unwanted light emitted by OLEDs which has overlaped with the fluorescence spectrum of the dyes. The distance between OLED illuminant and microchannels is limited to approximately 1 mm for sensitive detection. The achieved fluorescence signal of 300 microM Rhodamine 6G is about 13 times as high as that without the excitation filter and 3.5 times the result of a perpendicular detection structure. This system has been used for fluorescence detection of Rhodamine 6G, Alexa 532 and BSA conjugates in 4% linear polyacrymide (LPA) buffer (in 1 x TBE, pH 8.3) and 1.4 fmol and 35 fmol mass detection limits at 0.7 nl injection volume for Alexa and Rhodamine dye have been obtained, respectively.     

Crystal Structure and Molecular Absolute Configuration of （＋）－Isocedranol （C_（15）H_（26）O）

ＣｒｙｓｔａｌＳｔｒｕｃｔｕｒｅａｎｄＭｏｌｅｃｕｌａｒＡｂｓｏｌｕｔｅＣｏｎｆｉｇｕｒａｔｉｏｎｏｆ（＋）－Ｉｓｏｃｅｄｒａｎｏｌ（Ｃ_（１５）Ｈ_（２６）Ｏ）￥ＬｉｕＪｉｅ；ＣｈｅｎＭｉｎ－Ｑｉｎ（ＣｅｎｔｅｒｏｆＡｎａｌｙｓｉｓ＆Ｍｅａｓｕｒｅｍ...     

Simultaneous EQCM and diffuse reflectance UV-visible spectroelectrochemical measurements: poly(aniline-co-o-anthranilic acid) growth and property characterization

Piezoelectric diffuse reflectance spectroelectrochemistry (PDRSEC), a new technique of diffuse reflectance spectroelectrochemistry (DRSEC) in combination with electrochemical quartz crystal microbalance (EQCM), was developed to study the electrochemical copolymerization of aniline and o-anthranilic acid in 1.0 mol l(-1) HClO4 and the properties of these copolymers. The DRSEC using an integral sphere was proven to possess a higher optical sensitivity at the unpolished piezoelectric quartz crystal electrodes used than the mirror reflectance spectroelectrochemistry mode. The copolymers grown from the copolymerization bath of different molar fractions of o-anthranilic acid (F1, relative to the total amount of the two monomers) showed intermediate properties between those of the homopolymers, which varied gradually with F1. The swelling/dissolution behavior of the copolymers vs solution pH was traced via the EQCM frequency and resistance signals, and its large dependence on F1 was found and discussed. In a HAc-NaAc buffer solution at pH 5.6, the amount of adsorbed lysozyme was found to be positively correlated with F1, via an EQCM impedance investigation, demonstrating the feasibility of using poly(aniline-co-o-anthranilic acid) as a load-adjustable immobilization matrix for cationic proteins. The novel PDRSEC method proposed is highly recommended for surface electrochemistry studies at relatively rough electrodes.