Suppression of the internal electric field effects in ZnO/Zn(0.7)Mg(0.3)O quantum wells by ion-implantation induced intermixing

Strong suppression of the effects caused by the internal electric field in ZnO/ZnMgO quantum wells following ion-implantation and rapid thermal annealing, is revealed by photoluminescence, time-resolved photoluminescence, and band structure calculations. The implantation and annealing induces Zn/Mg intermixing, resulting in graded quantum well interfaces. This reduces the quantum-confined Stark shift and increases electron-hole wavefunction overlap, which significantly reduces the exciton lifetime and increases the oscillator strength.     

Nano-graphene oxide for cellular imaging and drug delivery

Two-dimensional graphene offers interesting electronic, thermal, and mechanical properties that are currently being explored for advanced electronics, membranes, and composites. Here we synthesize and explore the biological applications of nano-graphene oxide (NGO), i.e., single-layer graphene oxide sheets down to a few nanometers in lateral width. We develop functionalization chemistry in order to impart solubility and compatibility of NGO in biological environments. We obtain size separated pegylated NGO sheets that are soluble in buffers and serum without agglomeration. The NGO sheets are found to be photoluminescent in the visible and infrared regions. The intrinsic photoluminescence (PL) of NGO is used for live cell imaging in the near-infrared (NIR) with little background. We found that simple physisorption via π-stacking can be used for loading doxorubicin, a widely used cancer drug onto NGO functionalized with antibody for selective killing of cancer cells in vitro. Owing to its small size, intrinsic optical properties, large specific surface area, low cost, and useful non-covalent interactions with aromatic drug molecules, NGO is a promising new material for biological and medical applications. Electronic Supplementary Material  Supplementary material is available for this article at and is accessible for authorized users. This article is published with open access at Springerlink.com     

Effect of oil-droplet size on the oxidation of microencapsulated methyl linoleate

Effects of oil-droplet size, the weight ratio of oil to wall material and the storage temperature on the oxidation of methyl linoleate microencapsulated with maltodextrin by spray-drying were examined. The oxidation of methyl linoleate was more retarded for the microcapsules prepared from the emulsion having smaller oil droplets. The oxidation was more suppressed for the microcapsules having a lower weight ratio of oil to wall material. The fraction of unoxidized methyl linoleate leveled off after 10- to 15-days storage. The level, Y(infinity), depended on the weight ratio. The dependence of Y(infinity) on the weight ratio was analyzed based on the percolation theory, and the three-dimensional model of the theory was suitable to express the dependence. The effect of the storage temperature on the oxidation of microencapsulated methyl linoleate was also examined, and the activation energy was evaluated. The value of the energy suggested that the oxidation itself was a rate-limiting step for the oxidation of methyl linoleate encapsulated with maltodextrin.     

酯交换法同时合成碳酸二甲酯及乙二醇

研究了常压下无机酸碱及醇钠对酯交换合成碳酸二甲酯反应的催化活性 ,发现催化剂的碱性更能促进反应的进行 ,并从反应物结构上进行了分析。首次对卤化季铵盐及无机卤化盐的催化活性进行了研究 ,提出了可能的反应机理。     

Near‐Infrared Fluorescent Silica/Porphyrin Hybrid Nanorings for In Vivo Cancer Imaging

Ring‐shaped silica nanoparticles are synthesized with a high tetrakis(4‐carboxyphenyl)porphyrin (TCPP) content or silica/TCPP hybrid nanorings (HNRs) using a one‐pot sol‐gel reaction with a TCPP‐binding silica precursor for fluorescence imaging of tumor. The shape of the HNRs is a reflection of abundant ring‐shaped TCPP aggregates in the silica matrix. The HNRs are of a size that makes them susceptible to the enhanced permeability and retention effect. For comparison, the TCPP‐doped silica nanoparticles are synthesized using a conventional method. The nanoparticles are spherical in shape because little TCPP is contained in the silica matrix and are designated as TCPP‐containing silica nanospheres (NSs). The absorption bands of the HNRs shift by about 20 nm toward longer wavelengths compared with the TCPP bands. This redshift leads the excitation wavelength of the HNRs into the near‐infrared (NIR) region. Therefore, the HNRs are excited by NIR light to emit strong fluorescence, although the NSs emit no fluorescence. The PEGylated HNRs (PEG‐HNRs) are uncharged and possess a significantly longer blood circulation time than PEG‐NSs. The PEG‐HNRs accumulate in tumor through multiple factors including their size, uncharged surface, unique shape, and long circulation time in blood, resulting in the acquisition of clear images of tumor.     

南海北部中生界地震勘探震源设计及应用

基于南海北部中生界勘探面临的复杂地震地质条件,为改善该海域地震勘探难点区的资料质量,本文设计出6400in3的Bolt长寿枪震源,其特点是震源子波输出峰值和低频段能量得到加强,低频端由8Hz拓展到6Hz。通过对野外试验及实际海上地震勘探数据采集的效果的分析、对比,证实所设计的震源适用于南海北部中生界的油气资源探测。     

新型双金属自密封波齿复合垫片的应用

工程建设中难免出现复杂情况,装置运行中难免出现压力和温度的波动,现有的垫片的密封性能已难以满足这些要求。近期由广州市东山南方密封件公司研制开发的专利产品一双金属自密封波齿复合垫片是一种具有“压力自密封”特性的新型垫片。介绍了该垫片在金陵公司的几个装置上的成功应用实例,表明该垫片为解决目前石化装置的泄漏难题提供了很好的方法。     

新型双金属自密封波齿复合热片结构及其性能特点

介绍了最新专利产品—双金属自密封波齿复合垫片的基本结构及其密封性能特点。试验研究和实际应用表明,该垫片不仅保留了以往柔性石墨金属波齿复合垫片的一系列优异性能,而且具有与普通＂强制密封＂型垫片完全不同的＂压力自密封＂特性,其密封性能更为可靠。     

Origin of defect-insensitive emission probability in In-containing (Al,In,Ga)N alloy semiconductors

Group-III-nitride semiconductors have shown enormous potential as light sources for full-colour displays, optical storage and solid-state lighting. Remarkably, InGaN blue- and green-light-emitting diodes (LEDs) emit brilliant light although the threading dislocation density generated due to lattice mismatch is six orders of magnitude higher than that in conventional LEDs. Here we explain why In-containing (Al,In,Ga)N bulk films exhibit a defect-insensitive emission probability. From the extremely short positron diffusion lengths (<4 nm) and short radiative lifetimes of excitonic emissions, we conclude that localizing valence states associated with atomic condensates of In-N preferentially capture holes, which have a positive charge similar to positrons. The holes form localized excitons to emit the light, although some of the excitons recombine at non-radiative centres. The enterprising use of atomically inhomogeneous crystals is proposed for future innovation in light emitters even when using defective crystals.