Directly generating vortex beams in the second harmonic by a spirally structured fundamental wave

Based on nonlinear wave mixing, we experimentally propose a scheme for directly generating optical orbital angular momentum(OAM) by a spirally structured fundamental wave interacting with a nonlinear medium, in which the nonlinear susceptibilities are homogenous. In the experiment, the second-harmonic generation of a fundamental wave carrying positive(negative) integers and fractional OAM states was investigated. This study presents a convenient approach for dynamic control of OAM of vortex beams, which may feature their applications in optical manipulation and optical communication.     

Hysteresis effects of the interaction between serum albumins and silver nanoparticles

In recent years, nanomaterials have wide-ranging implications to a variety of areas, including chemistry and biology sciences, and the emerged new fields, nanochemistry and nanobiology, have received considerable attention. The latest studies show that the unique optical, electronic and magnetic properties make nanoparticles useful for applications in the fields of bio-analysis, diseases diagnosis and medicine[1—9]. With particular optoelectronic properties, the silver nanoparticles have…     

复合材料内部传导系数的唯一性定理

将考虑Rn(n≥2)中有界Lipschitz区域上,分片常系数复合材料折射问题的反问题.我们将利用层位势技巧,通过单测量数据——非零Neumann边值来确定内部材料传导系数的唯一性.     

Existence and nonexistence theorem for entire subsolutions of k-Yamabe type equations

In this paper, we consider fully nonlinear elliptic equations related to Yamabe problem. We improve a result of Jin, Li and Xu and establish the existence and nonexistence for positive entire subsolutions with a generalized Keller–Osserman condition.     

Researches on the distribution law of vector sound field in elastic wedge bottom

The method based on elastic parabolic equation method for calculating the sound vector field has been studied.The vector field in water and corresponding seismic wave field had been calculated for infra-sound in oceanic environment with elastic wedge bottom.The effects on sound field distribution for different frequency and depth of sound source had been researched,result shows that there is sound energy leakage into the bottom,the position where leakage occurred can be determined by the ratio of the ocean depth to the wavelength,as compared with normal mode theory.     

含钛高炉渣钛组分富集-分选试验研究

对攀钢集团有限公司含钛高炉水淬渣进行定向富集,并对富集渣进行浮选研究.结果表明,在焙烧温度为1 250 ℃、碱度R=3.0、渣中CaF2加入量为6%、焙烧时间为4 h及冷却速率为10 ℃/min的条件下,钙钛矿的晶粒可长大到40 μm左右;在羟肟酸用量为12 kg/t,pH值为9,起泡剂为2#油的条件下进行浮选,精矿中TiO2品位可达到50%左右,TiO2回收率约为35%;尾矿中TiO2品位在10%左右.     

碱溶液修饰硅纳米线阵列绒面

提出用碱溶液修饰硅纳米线阵列制作太阳能绒面的方法。实验中首先采用金属催化化学腐蚀法在Si(100)基底上制备了定向排列的硅纳米线阵列,然后将纳米线阵列浸入碱溶液中进行修饰,修饰时间分别为10,30,50,60,90s。通过扫描电子显微镜(SEM)对硅纳米线阵列进行形貌分析,采用太阳能测试系统附带的积分球测量纳米线阵列绒面结构的反射光谱。通过测量和分析发现硅纳线阵列在碱溶液中修饰30s时表面分布均匀,在400～1000nm波段的综合反射率低于4%。结果表明碱溶液修饰纳米线阵列的方法能够有效分散束状硅纳米线阵列,明显降低绒面的反射率,并且初步分析了碱溶液修饰硅纳米线阵列的分散机理。     

Thermal Decomposition Behavior of Poly (Vinyl Alcohol) with Different Hydroxyl Content

The thermal decomposition behavior of poly(vinyl alcohol) (PVA) with two different hydroxyl contents, 88 and 99%, was investigated. UV-Vis spectroscopy, thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and TGA-FTIR were used to detect the volatile and nonvolatile products of the thermal decomposition of PVA. The results suggest that the PVA, after thermal treatment, can form chromophoric polyene structure, as well as carbonyl groups. The PVA with 88% hydroxyl content underwent slower decomposition below 280°C and generated water and carboxyl acid as the dominant volatile products, however, as for the PVA with 99% hydroxyl content, the dominant volatile products were water, unsaturated aldehydes, and other unsaturated compounds.     

可压缩旋转恒星的存在性与稳定性理论

旋转是宇宙中的一个普遍现象.从Newton时代开始,许多著名的数学家和物理学家如:Maclaurin,Clairaut,Liouville,Lyapunov,Poincare等人都对旋转星理论作出过非常重要的贡献.旋转星理论中一个基本的问题就是研究自重力旋转流体相对平衡结构的存在性与稳定性,这个问题至今没有完全解决.本文将尝试对其研究历史作一些综述,给出近年来的一些最新进展,并介绍一些未解决的问题.     

Study of the Thermal Decomposition Behavior of Poly(vinyl alcohol) with NaHSO4

The thermal decomposition behavior of poly(vinyl alcohol) (PVA) with NaHSO₄ at 280～290°C as well as the optical characteristics and the thermal stability of the resulting thermally decomposed PVA were investigated by means of UV-Vis spectroscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The results suggest that (1) the elimination reactions of side groups in PVA with NaHSO₄ can occur under our conditions resulting in formation of carbon–carbon double and triple bonds; (2) most of the carbon–carbon double bonds were conjugated; (3) the PVA thermally treated with NaHSO₄ could absorb light in the region of 190～600 nm; (4) the thermal stability of the resulting PVA was better than that of PVA without thermal treatment; and (5) compared with the thermal reaction of PVA without NaHSO₄, the addition of NaHSO₄ can promote the thermal elimination of side groups of PVA.