Lower work function of thermoelectric material by ordered arrays

In this paper, PbTe nanocubes are assembled on Bi_0.5Sb_1.5Te₃ substrates with both ordered and disordered structures through a straightforward method to form a P-N section. The work function of such semiconductor system is then measured by the ultraviolet photoelectron spectroscopy. This results show that the work function of orderly arrayed PbTe deposition is much lower than the disordered assemblies. Such change of the work function provides the possibility to tune it in a P-N section system. The change of the work function is attributed to the less surface roughness and easier electron escaping in the ordered structures.     

Nickel‐Catalyzed Cross‐Coupling of Redox‐Active Esters with Boronic Acids

A transformation analogous in simplicity and functional group tolerance to the venerable Suzuki cross‐coupling between alkyl‐carboxylic acids and boronic acids is described. This Ni‐catalyzed reaction relies upon the activation of alkyl carboxylic acids as their redox‐active ester derivatives, specifically N‐hydroxy‐tetrachlorophthalimide (TCNHPI), and proceeds in a practical and scalable fashion. The inexpensive nature of the reaction components (NiCl₂?6 H₂O—$9.5 mol^?1, Et₃N) coupled to the virtually unlimited commercial catalog of available starting materials bodes well for its rapid adoption.     

A new tigliane-type diterpene from Euphorbia dracunculoides Lam

One new tigliane-type diterpene, 4-deoxy-4(β)H-8-hydroperoxyphorbol-12-benzoate-13-isobutyrate (1), together with two known diterpenoids, 3-acetyl-5,8-dibenzoyl-14α-propanoyl-13,17-epoxy-7-myrsinaone diterpene with C9–C10 cyclised to form an additional lactone ring (2), Euphodendriane A (3) have been isolated from the whole plants of Euphorbia dracunculoides Lam. Their structures were elucidated by means of extensive spectroscopic analysis (NMR and HR-ESI-MS) and comparison with data reported in the literature. This is the first isolation of 8-hydroperoxy tigliane diterpene (1) from the genus of Euphorbia. All compounds were evaluated for their antifungal activities.     

Thermal annealing of Au nanorod self-assembled nanostructured materials: morphology and optical properties

Three-dimensional Au nanorod and Au nanoparticle nanostructured materials were prepared by layer-by-layer self-assembly. The plasmonic properties of the Au nanorod and Au nanoparticle self-assembled nanostructured materials (abbreviated as AuNR and AuNP SANMs) are tunable by the controlled self-assembly process. The effect of thermal annealing at 180 and 500 degrees C to the morphologies, plasmonic properties and surface-enhanced Raman scattering (SERS) responses of these SANMs were investigated. According to the experimental results, these properties correlate with the structure of the SANMs.     

强磁场条件下金属凝固过程中第二相的迁移行为

理论分析表明,第二相的迁移行为可以通过迁移速度进行表征.影响迁移速度的因素包括第二相和熔体的物理性质、磁场强度和梯度大小、第二相的形状和体积等因素.强磁场下洛伦兹力的效果为促进第二相在基体中的均匀分布,其效率在磁场强度大于某一定值时逐渐降低.在梯度强磁场条件下,第二相迁移行为和分布状态的主要控制参数是梯度磁场下的磁化力.在磁场梯度较小时,因洛伦兹力的制约磁化力控制第二相迁移的效果不明显,随着磁场梯度的增加,磁化力的作用效果逐渐增强.通过研究强磁场下Al-Si合金、Al-Ni合金中原位自生第二相的迁移行为实 关键词： 强磁场 迁移 第二相 凝固     

不同过渡层上Co/Cu/Co三明治结构的巨磁电阻效应研究

通过对不同过渡层上Co(5.5nm)/Cu(3.5nm)/Co(5.5nm)三明治结构的研究,发现过渡层的磁性及过渡层诱导的三明治晶格结构对材料的巨磁电阻效应有重要影响.反铁磁Cr过渡层由于和相邻铁磁Co层之间存在着反铁磁耦合,可以获得6％以上的巨磁电阻值,但它同时使材料的矫顽力较大,因此磁灵敏度不高.Ni和Ti过渡层上Co/Cu/Co三明治结构,由于形成了强的（111）织构,其巨磁电阻值也达到5％以上.磁性材料Ni过度层还使三明治结构材料的矫顽力大为下降,从而显著提高了材料的磁灵敏度. 关键词：     

六方稀土氧化物水化和碳酸化产物的振动光谱研究

六方稀土氧化物在空气中极易水化和碳酸化。测定并讨论了光谱纯粉晶ＲＥ２Ｏ３（ＲＥ＝ Ｌａ ,Ｐｒ,Ｎｄ） 样品的Ｒａｍａｎ 光谱、红外光谱及粉晶Ｘ 射线衍射谱。结果表明, 其水化产物为ＲＥ（ＯＨ）３ , 碳酸化产物主要为六方双氧单碳酸盐ＲＥ２Ｏ３ＣＯ３ 以及少量的单氧双碳酸盐ＲＥ２Ｏ（ＣＯ３）２ 和四方ＲＥ２Ｏ２ＣＯ３ 。     

哒嗪酮的乙酰胺类化合物的合成及生物活性

2-叔丁基-4-氯-5-羟基-哒嗪-3(2H)-酮(3)与相应的N-烷基或N,N-二烷基氯乙酰胺(4a-4l)反应,合成了2-叔丁基-5-[(N-烷基或N,N-二烷基乙酰胺)氧基]-4-氯-哒嗪-3(2H)-酮(1a-1l),生物活性测定结果表明部分化合物(1a-1l)具有杀虫活性。     

Origin,evolution,and distribution of atmospheric aerosol particles in Asia

In recent years,Asia became the region with the highest increase in rate of urbanization and economic development in the world.According to recent estimates from the United Nations,the world population will increase 36%between 2000 and 2030,leading to a doubling of the number of urban dwellers in less developed regions,like Asia.Such rapid economic development has many associated environmental problems,including development of heavy aerosol pollution over Asia.Aerosol particles have a direct radiative forcing effect on climate because they scatter and absorb solar and infrared     

一种新的USED CARS相位匹配实现技术

相位匹配是相干反斯托克斯拉曼散射(CARS)测温的关键技术之一,针对现有非稳腔空间增强探测(USED)相位匹配方式中存在的背景辐射大、光路调试不灵活以及斯托克斯光利用率低的不足,提出了一种新的USED CARS相位匹配实现方案：即设计一个与斯托克斯光斑大小相当、呈45°斜角的斜反镜,用于反射全部斯托克斯光,并以斜反镜代替传统USED CARS中的环反镜,让泵浦光从斜反镜后方射入,从而形成USED相位匹配方式。新的USED CARS相位匹配方案中：由于斜反镜面积相对于环反镜大为减小,使得因反射而进入光路的背景辐射大幅降低;斜反镜本身可作为光路调节元件,因而增加了光路调试灵活度;斯托克斯光被斜反镜全部反射用于产生CARS信号,提高了其利用效率。基于平面火焰炉稳态火焰开展的测温实验结果表明：新的USED CARS相位匹配方案不但克服了传统USED CARS中存在的不足,而且具有更小的标准差,是一种更为有效的相位匹配方法。