Effects of Silver Island Films on the Luminescent Intensity and Decay Times of Lanthanide Chelates

We examined the emission intensity and decay times of chelates Tb³⁺ and Eu³⁺ in micron thick samples between films of sub-wavelength size silver particles. We observed modest increases in emission intensities for the complexes between the silver particles as compared to between unsilvered quartz plates. The intensity decay times were dramatically decreased by the silver particles, which was in part mediated by diffusion toward the silver particles. These results indicated that luminescent lanthanides in close proximity to silver particles display increased rates of radiative decay. The use of luminophore-metallic surface interactions provides new opportunities for creation of luminescent probes with novel spectral properties.     

浙江温岭石塘沿海岛屿的潮间带贝类资源

报告了浙江省温岭市石塘镇沿海岛屿的潮间带贝类33种，其中腹足类22种，多板类6种，双壳类5种，主要经济种类有7种。并就岛屿岩相潮间带贝类种类组成、生态特点、群落特征进行了分析，最后对经济种类的保护、开发和利用提出了建议。     

反常输运与非线性自持磁岛的自洽分析

从沿磁力线的等离子体电流与粒子径向输运相关的新经典ＭＨＤ型的广义欧姆定律出发，提出了分析反常输运与非线性自持磁岛的自洽理论模型，基于该模型导出了反常扩散系数及反常电子热导。结果表明，非线性磁岛链可由磁岛调制的反常输动维持，反过来又通过磁岛短路效应维持反常输运。     

Shape, facet evolution and photoluminescence of Ge islands capped with Si at different temperatures

We investigate the embedding of Ge islands in a Si matrix by means of atomic force microscopy and photoluminescence (PL) spectroscopy. The Ge islands were grown between 360°C and 840°C and subsequently capped with Si at different temperatures. For the highest Ge growth temperature (840°C), we show that the surface flattens at high Si capping temperatures while new facets can be identified at the island base for intermediate capping temperatures (650–450°C). At low capping temperatures (300–350°C), the island morphology is preserved. In contrast to the observed island shape changes, the decreasing Si capping temperature causes only a small redshift of the island related PL signal for islands grown on high temperatures. This redshift increases for Ge islands grown at lower temperatures due to an increased Ge content in the islands. By applying low-temperature capping (300°C) on the different island types, we show that the emission wavelength can be extended up to 2.06 μm for hut clusters grown at 400°C. Further decreasing of the island growth temperature to 360°C leads to a PL blueshift, which is explained by charge carrier confinement in Ge quantum dots.     

Size effect in electron-lattice energy exchange in small metal particles

The paper examines electron-lattice energy exchange in confined metal systems (metal islands). An expression is derived for the energy, which an electron loses per unit of time to initiate acoustic oscillations in the lattice in accordance to the Cherenkov mechanism. In confined metal systems an electron moves, oscillating, from one potential wall to the other. The expression obtained for energy exchange converts to the generally known expression for bulk metals when the distance between the potential walls is increasing. The intensity of the bulk electron-lattice energy exchange oscillates and tends to zero at reaching a certain size with decrease of the distance between the walls.     

Photostability of Cy3 and Cy5-Labeled DNA in the Presence of Metallic Silver Particles

We examined the photostability of a double-stranded DNA oligomer, covalently labeled with Cy3 or Cy5 on one strand, in the presence of metallic silver island films. In our experimental configuration a minor fraction of the labeled DNA was close to the silver particles and the remainder was distant from the particles. Proximity of the fluorophores to silver island films resulted in increased intensity. Upon continuous illumination we found a fraction of the emission that was resistant to the photobleaching. The emission spectra of the residual fractions were identical to the initial spectra. The frequency-domain lifetime measurements of this fraction revealed greatly shortened decay times. These results are consistent with the photostable fraction being close to the silver particles. This results suggest that the number of photons detected per fluorophore, prior to photobleaching, can be increased 5-fold or more by proximity to silver particles. Localization at an optimal distance from the silver surface may result in larger enhancements.     

DNA methylation-regulated microRNA pathways in ovarian serous cystadenocarcinoma: A meta-analysis

Epigenetic regulation has been linked to the initiation and progression of cancer. Aberrant expression of microRNAs (miRNAs) is one such mechanism that can activate or silence oncogenes (OCGs) and tumor suppressor genes (TSGs) in cells. A growing number of studies suggest that miRNA expression can be regulated by methylation modification, thus triggering cancer development. However, there is no comprehensive in silico study concerning miRNA regulation by direct DNA methylation in cancer. Ovarian serous cystadenocarcinoma (OSC) was therefore chosen as a tumor model for the present work.Twelve batches of OSC data, with at least 35 patient samples in each batch, were obtained from The Cancer Genome Atlas (TCGA) database. The Spearman rank correlation coefficient (SRCC) was used to quantify the correlation between the CpG DNA methylation level and miRNA expression level. Meta-analysis was performed to reduce the effects of biological heterogeneity among different batches. MiRNA-target interactions were also inferred by computing SRCC and meta-analysis to assess the correlation between miRNA expression and cancer-associated gene expression and the interactions were further validated by a query against the miRTarBase database.A total of 26 potential epigenetic-regulated miRNA genes that can target OCGs or TSGs in OSC were found to show biological relevance between DNA methylation and miRNA gene expression. Furthermore, some of the identified DNA-methylated miRNA genes; for instance, the miR-200 family, were previously identified as epigenetic-regulated miRNAs and correlated with poor survival of ovarian cancer. We also found that several miRNA target genes, BTG3, NDN, HTRA3, CDC25A, and HMGA2 were also related to the poor outcomes in ovarian cancer.The present study proposed a systematic strategy to construct highly confident epigenetic-regulated miRNA pathways for OSC. The findings are validated and are in line with the literature. The inclusion of direct DNA methylated miRNA events may offer another layer of explanation that along with genetics can give a better understanding of the carcinogenesis process.     

InAs quantum dots in GaAs holes: island number dependence on hole diameter and conduction-band coupling estimates

We studied the formation of InAs islands in holes defined by electron-beam lithography on GaAs substrates. The islands grew selectively in the holes, with one to nine islands per hole. The number of islands depends simply on the hole diameter, filling the holes at a constant effective two-dimensional density. We define the ratio of this effective density to the density on an unpatterned control sample to be the selectivity ratio, and we find a selectivity ratio of greater than 1000 for the present samples. We estimated the lateral conduction-band coupling for closely spaced islands and conclude them to be plausible candidates for weakly coupled device building blocks.     

A novel planar vertical double-diffused metal-oxide- semiconductor field-effect transistor with inhomogeneous floating islands

A novel planar vertical double-diffused metal-oxide-semiconductor (VDMOS) structure with an ultra-low specific on-resistance (R_on,sp), whose distinctive feature is the use of inhomogeneous floating p-islands in the n-drift region, is proposed. The theoretical limit of its R_on,sp is deduced, the influence of structure parameters on the breakdown voltage (BV) and R_on,sp are investigated, and the optimized results with BV of 83 V and R_on,sp of 54 mOmega cdotmm² are obtained. Simulations show that the inhomogeneous-floating-islands metal-oxide-semiconductor field-effect transistor (MOSFET) has a superior “R_on,sp/BV” trade-off to the conventional VDMOS (a 38% reduction of R_on,sp with the same BV) and the homogeneous-floating-islands MOSFET (a 10% reduction of R_on,sp with the same BV). The inhomogeneous-floating-islands MOSFET also has a much better body-diode characteristic than the superjunction MOSFET. Its reverse recovery peak current, reverse recovery time and reverse recovery charge are about 50, 80 and 40% of those of the superjunction MOSFET, respectively.     

The influence of annealing temperature on the morphology of graphene islands

We report on temperature-programmed growth of graphene islands on Ru(0001) at annealing temperatures of 700°C,800°C,and 900°C.The sizes of the islands each show a nonlinear increase with the annealing temperature.In 700°C and 800°C annealings,the islands have nearly the same sizes and their ascending edges are embedded in the upper steps of the ruthenium substrate,which is in accordance with the etching growth mode.In 900°C annealing,the islands are much larger and of lower quality,which represents the early stage of Smoluchowski ripening.A longer time annealing at 900°C brings the islands to final equilibrium with an ordered moir’e pattern.Our work provides new details about graphene early growth stages that could facilitate the better control of such a growth to obtain graphene with ideal size and high quality.