Propagation of Microplasma Discharge over Titanium Surface Covered with Thin Dielectric Film

Plasma Physics Reports - Propagation and structure of the pulsed microplasma discharge initiated on the titanium sample surface covered with a thin dielectric film with a thickness of approximately...     

Surface Plasmon Polariton Modes at Interface of a Metal and an Ambichiral Sculptured Thin Film

The excitation of surface plasmon polariton (SPP) at interface of a metal and an ambichiral sculptured thin film was theoretically investigated in the Kretschmann configuration using the transfer matrix method. The dependence of SPP modes for a P polarization plane wave on the incident angle of light and the angle of rise of nanocolumns of ambichiral dielectric medium was reported. We found that multiple SPP modes are excited at the interface of metal and ambichiral dielectric medium. The results of phase speed as a function of pitch showed only that a SPP mode can be excited at all pitches.     

A Surface Design for Enhancement of Light Trapping Efficiencies in Thin Film Silicon Solar Cells

We report on a surface design of thin film silicon solar cells based on silver nanoparticle arrays and blazed grating arrays. The light transmittance is increased at the front surface of the cells, utilizing the surface plasmon resonance effect induced by silver nanoparticle arrays. As a reflection layer structure, blazed gratings are placed at the rear surface to increase the light reflectance at bottom of the thin film cells. With the combination of the silver nanoparticle arrays and the blazed gratings, the light trapping efficiency of the thin film solar cell is characterized by its light absorptance, which is determined from the transmittance at front surface and the reflectance at bottom, via the finite-difference time-domain (FDTD) numerical simulation method. The results reveal that the light trapping efficiency is enhanced as the structural parameters are optimized. This work also shows that the surface plasmon resonance effect induced by the silver nanoparticles and the grating characteristics of the blazed gratings play crucial roles in the design of the thin film silicon solar cells.     

Synthesis and Characterization of High c-axis ZnO Thin Film by Plasma Enhanced Chemical Vapor Deposition System and its UV Photodetector Application

In this study, zinc oxide (ZnO) thin films with high c-axis (0002) preferential orientation have been successfully and effectively synthesized onto silicon (Si) substrates via different synthesized temperatures by using plasma enhanced chemical vapor deposition (PECVD) system. The effects of different synthesized temperatures on the crystal structure, surface morphologies and optical properties have been investigated. The X-ray diffraction (XRD) patterns indicated that the intensity of (0002) diffraction peak became stronger with increasing synthesized temperature until 400 ^oC. The diffraction intensity of (0002) peak gradually became weaker accompanying with appearance of (10-10) diffraction peak as the synthesized temperature up to excess of 400 ^oC. The RT photoluminescence (PL) spectra exhibited a strong near-band-edge (NBE) emission observed at around 375 nm and a negligible deep-level (DL) emission located at around 575 nm under high c-axis ZnO thin films. Field emission scanning electron microscopy (FE-SEM) images revealed the homogeneous surface and with small grain size distribution. The ZnO thin films have also been synthesized onto glass substrates under the same parameters for measuring the transmittance.For the purpose of ultraviolet (UV) photodetector application, the interdigitated platinum (Pt) thin film (thickness ~100 nm) fabricated via conventional optical lithography process and radio frequency (RF) magnetron sputtering. In order to reach Ohmic contact, the device was annealed in argon circumstances at 450 ^oC by rapid thermal annealing (RTA) system for 10 min. After the systematic measurements, the current-voltage (I-V) curve of photo and dark current and time-dependent photocurrent response results exhibited a good responsivity and reliability, indicating that the high c-axis ZnO thin film is a suitable sensing layer for UV photodetector application.     

Excitation of Multiple Surface Plasmon-Polaritons by a Metal Layer Inserted in an Equichiral Sculptured Thin Film

Excitation of multiple surface plasmon-polaritons (SPPs) by an equichiral sculptured thin film with a metal layer defect was studied theoretically in the Sarid configuration, using the transfer matrix method. Multiple SPP modes were distinguished from waveguide modes in optical absorption for p-polarized plane wave. The degree of localization of multiple SPP waves was investigated by calculation of the time-averaged Poynting vector. The results showed that the long-range and short-range SPP waves can simultaneously be excited at both interfaces of metal core in this proposed structure which may be used in a broad range of sensing applications.     

Fabrication of Ag Nanoparticles Embedded in Al:ZnO as Potential Light-Trapping Plasmonic Interface for Thin Film Solar Cells

Incident photon conversion efficiency of the absorbing materials at either side of a thin film solar module can be enhanced by integrating a plasmonic interface. Silver nanoparticles represent a good candidate that can be integrated to a thin film solar cell for efficient light-trapping. The aim of this work is to fabricate plasmonically active interface consisting of Ag nanoparticles embedded in Al:ZnO that has the potential to be used at the front surface and at the back reflector of a thin film solar cell to enhance light-trapping and increase the photoconversion efficiency. We show that Ag can readily dewet the Al:ZnO surface when annealed at temperatures significantly lower than the melting temperature of Ag, which is beneficial for lowering the thermal budget and cost in solar cell fabrication. We find that such an interface fabricated by a simple dewetting technique leads to plasmonic resonance in the visible and near infrared regions of the solar spectrum, which is important in enhancing the conversion efficiency of thin film solar cells.     

Light‐Driven Highly Selective Conversion of CO2 to Formate by Electrosynthesized Enzyme/Cofactor Thin Film Electrode

The highly selective electrochemical reduction of carbon dioxide (CO₂) is reported to formate (HCOO^‐) at a compactly integrated bioelectrode. The enzymatic biocatalytic cathode is fabricated by single‐step electropolymerization of a multifunctional polydopamine film in which enzyme/cofactor couples are uniquely embedded. Interestingly, this thin biohybrid system of nanoscale thickness assures unprecedentedly prolonged catalytic enzyme stability for about two weeks. Mimicking the natural photosynthesis, combination with the photoanode utilizing the water oxidation, steadily produces formate at a faradaic efficiency of 99.18 ± 6.77% with little degradation at least for 1 d under 1 sun illumination and no external bias.     

Surface Electronic Modification of Perovskite Thin Film with Water‐Resistant Electron Delocalized Molecules for Stable and Efficient Photovoltaics

Although the efficiency of perovskite solar cells (PSCs) is close to crystalline silicon solar cells, the instability of perovskite, especially in humid condition, still hinders its commercialization. As an effective method to improve their stability, surface functionalization, by using hydrophobic molecules, has been extensively investigated, but usually accompanied with the loss of device efficiencies owing to their intrinsic electrical insulation. In this work, for the first time, it is demonstrated that 3‐alkylthiophene‐based hydrophobic molecules can be used as both water‐resistant and interface‐modified layers, which could simultaneously enhance both stability and performance significantly. Benefitting from their unique structures of thiophene rings, the π‐electrons are highly delocalized and thus enhance the charge transfer and collection at the interface. The device based on 3‐hexylthiophene treatment exhibits a champion energy conversion efficiency of 19.89% with a dramatic 10% enhancement compared with the pristine one (18.08%) of Cs_0.05 FA_0.81 MA_0.14 PbBr_0.45 I_2.55‐based PSCs. More importantly, the degradation of the long‐term efficiency of unsealed device is less than 20% in Cs_0.05 FA_0.81 MA_0.14 PbBr_0.45I_2.55‐based PSCs after more than 700 h storage in air. This finding provides an avenue for further improvement of both the efficiency and stability of PSCs.     

Effect of Graphene on the Sunlight Absorption Rate of Silicon Thin Film Solar Cells

The electromagnetic property of graphene is studied by finite-difference time-domain (FDTD) method. As the graphene has excellent electrical conductivity and high transparency, it has certain advantages as a transparent electrode for solar cells. This paper designs a three-layer film structure composed of graphene, silicon, and silicon dioxide (SiO₂). Then, the effects of the chemical potential and the scattering rate of the graphene on the light absorption of the film are studied. The study found that the electromagnetic property of graphene is relatively stable, which is not easily influenced by the external environment. After changing its chemical potential, scattering rate, and other parameters, it is found that the film absorption rate is less affected unless the large range of chemical potential changes; it will lead to a decline in the absorption rate of light.

     

Sequential Logic of Polarity Determination during the Haploid-to-Diploid Transition in Saccharomyces cerevisiae

In many organisms, the geometry of encounter of haploid germ cells is arbitrary. In Saccharomyces cerevisiae, the resulting zygotes have been seen to bud asymmetrically in several directions as they produce diploid progeny. What mechanisms account for the choice of direction, and do the mechanisms directing polarity change over time? Distinct subgroups of cortical “landmark” proteins guide budding by haploid versus diploid cells, both of which require the Bud1/Rsr1 GTPase to link landmarks to actin. We observed that as mating pairs of haploid cells form zygotes, bud site specification progresses through three phases. The first phase follows disassembly and limited scattering of proteins that concentrated at the zone of cell contact, followed by their reassembly to produce a large medial bud. Bud1 is not required for medial placement of the initial bud. The second phase produces a contiguous bud(s) and depends on axial landmarks. As the titer of the Axl1 landmark diminishes, the third phase ultimately redirects budding toward terminal sites and is promoted by bipolar landmarks. Thus, following the initial random encounter that specifies medial budding, sequential spatial choices are orchestrated by the titer of a single cortical determinant that determines whether successive buds will be contiguous to their predecessors.     

The Lipid Layer: The Outer Surface of the Ocular Surface Tear Film

The outer layer of the tear film—the lipid layer—has numerous functions. It is a composite monolayer composed of a polar phase with surfactant properties and a nonpolar phase. In order to achieve an effective lipid layer, the nonpolar phase, which retards water vapor transmission, is dependent on a properly structured polar phase. Additionally, this composite lipid layer must maintain its integrity during a blink. The phases of the lipid layer depend on both lipid type as well as fatty acid and alcohol composition for functionality. Surprisingly, the importance of the composition of the aqueous layer of the tear film in proper structuring of the lipid layer has not been recognized. Finally, lipid layer abnormalities and their relationship to ocular disease are beginning to be clarified.     

Effect of Ag Ion Implantation on SPR of Cu-C60 Nanocomposite Thin Film

Plasmonics - Cu-C60 nanocomposite thin films are synthesized by co-deposition restive heating method on glass, silicon, and TEM grid substrates. Rutherford backscattering spectroscopy (RBS)...     

The Determination of Spindle Polarity in Early Mitotic Stages of the Dividing Grasshopper Neuroblasts

Although the spindle body of the grasshopper neuroblasts at the early mitotic stages does not have any mechanical linkage to the surrounding cell cortex, a spindle axis is inevitably oriented in parallel with the original division axis. The present study analyzes how the definite orientation of spindle axis along the cap cell (CC)-ganglion cell (GC) axis of the neuroblast is maintained during these stages by use of the microdissection technique and electron microscopy. After removing a microneedle from the cell, metaphase spindles approximately 90°. rotated were able to return autonomously to the original axis. After the middle anaphase, however, the rotated spindle could not return at all. The electron microscopic observations revealed a characteristic behavior of an electron dense layer (EDL) in the CC-side cortex during neuroblast mitosis. The EDL first appeared at very late prophase and became most conspicuous at metaphase. It became discontinuous by the beginning of middle anaphase and then completely disappeared at middle anaphase. So long as an EDL existed in the CC-side polar cortex, 90° rotated spindle bodies were able to return autonomously to the original axis. After the disappearance of the EDL, the autonomous return of the rotated spindle no longer occurred. From these circumstantial evidence, it is conceivable that the orientation of the spindle body along the CC-GC axis is maintained by the interaction between the EDL and the spindle pole.     

Large Optical Nonlinearity of Surface Plasmon Modes on Thin Gold Films

We investigate the optical nonlinear effects of a long-range surface plasmon polariton mode propagating on a thin gold film. These effects may play a key role in the design of future nanophotonic circuits as they allow for the realization of active plasmonic elements. We demonstrate a significant enhancement of the transmission on a timescale below a millisecond as well as a phase shift exceeding 2π already for modest peak powers of 150 mW. On the contrary, slow effects suppress the transmission on a millisecond timescale.     

Polarity and stratification of the epidermis

Polarity is a fundamental property of epithelial cells. In this review, we discuss our current knowledge of the polarity of a stratified epithelium, the epidermis, focusing on similarities and differences with simple epithelial models. We highlight how the differences in tissue architecture and physiology result in alterations in some aspects of cell polarity. In addition, we discuss one of the most prominent uses for cell polarity in the epidermis-orienting the mitotic spindle to drive the stratification and differentiation of this tissue during development.     

马铃薯糖苷生物碱的薄层层析及扫描测定

 马铃薯糖苷生物碱的薄层层析及扫描测定段光明,冯育林,叶荩（山西大学生物学系,太原０３０００６１,山西大学测试中心,太原０３０００６）马铃薯糖苷生物碱（ｇｌｙｃｏａｌｋａｌｏｉｄｓ）是一类含氮甾族化合物,有明显的剧毒性和潜在的慢毒性［１］,其测定方法的...